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3-l/^XL

->*c

INTERNATIONAL
LIBRARY OF TECHNOLOGY

A SERIES OF TEXTBOOKS FOR PERSONS ENGAGED IN THE ENGINEERING

PROFESSIONS AND TRADES OR FOR THOSE WHO DESIRE

INFORMATION CONCERNING THEM. FULLY ILLUSTRATED

AND CONTAINING NUMEROUS PRACTICAL

EXAMPLES AND THEIR S(JLUTIONS

.-« ••

• • •

'• . «•

CARBURETERS .',. :,.

ELECTRIC IGiNTTlON; 'DEVICES-;

AUTOMOBILE AND MARlM'-Bi-ENdiw

AUXILIARIES '

POWER-GAS PRODUCERS

MANAGEMENT OF AUTOMOBILE ENGINES

MANAGEMENT OF MARINE GAS ENGINES

MANAGEMENT OF STATIONARY GAS ENGINES

TROUBLES AND REMEDIES

POWER DETERMINATIONS

6133dX

SCRANTON :
INTERNATIONAL TEXTBOOK COMPANY

THE NEW YORK
PUBLIC LIBRARY

AST OR, LFNOX AND

■ntn N fcm;ndation8.

1914

Entcrctl at Stationens' Hall. London.

re<l

CarburetCBB:. ^Cfjpyrijiht, 1UU7, by Intkrnational Tkxthqok Company. Entcro
at Statifrsci;?'^ Uall, ^"nd^n * • - ^ . » ,

Electric rKtlition 'DtviCes: "Goifiyrii^; a907, by International Textbook Com
PANY. Ente^iwl a^ SUitjgners' Kail, ""London.

Automobile and^ Mj^i*^ A^^ncf '^pxiliaries: Copyright, 1907, by Inteknationai.
TEXTHOOi^CoMpAhT?.* Swfe»5d aft Stationers' Hall, I.K)n(l()n,

Power-Gas PiYdi«;0^;*"^ (jnpiCrf^, MK)7, by International Textbook C(^mpanv.
Entered at ^tal vid^' >IkK* Xc^ndt^ .

**"*"**"■

Manaf[ement of Automobile Engines: Copyright. 1907, >)y International Text-
book Company. Entered at Stationers' Hall, I.xmdon.

Management of Marine Gas Engines: Copyright, 1U07, by Intp.knatidnal Text-
book Company. Enterwl at Stationers' Ilall, Lomlon.

Management of Stationary Oas Engines: Copyright, 11)07, by International Text
book Company. Entere<J at Stationers' Hall, London.

Troubles and Remedies: Copyright. HK)7, by International Textbook Com-
pany. Entered at Stationers' Hall, London.

Power Determinations: Copyright, 1907. by Intkrnational Textbook Cdmi'anv.
Entere<l at Stationers' Hall, London.

All rights reservcil.

PI^I^■TI^I• IN THE UnITKD STATIS.

<fg;

^'■■7 .".■■?*."iA

20270

iL,

PREFACE

The International Library of Technology is the outgrowth
of a large and increasing demand that has arisen for the
Reference Libraries of the International Correspondence
Schools on the part of those who are not students of the
Schools. As the volumes composing this Library are all
printed from the same plates used in printing the Reference
Libraries above mentioned, a few' woMs dre iiecessary
regarding the scope and purpose of' the instruction imparted
to the students of — and the class of stuUelits taught by —
these Schools, in order to afford a clear understanding of
their salient and uhique features. ' ' * *' •■

The only requirement for admission to any of the courses
offered by the International Correspondence Schools, is that
the applicant shall be able to read the English language and
to write it sufficiently well to make his written answers to
the questions asked him intelligible. Each course is com-
plete in itself, and no textbooks are required other than
those prepared by the Schools for the particular course
selected. The students themselves are from every class,
trade, and profession and from every country; they are,
almost without exception, busily engaged in some vocation,
and can spare but little time for study, and that usually
outside of their regular working hours. The information
desired is such as can be immediately applied in practice, so
that the student may be enabled to exchange his present
vocation for a more congenial one, or to rise to a higher level
in the one he now pursues. Furthermore, he wishes to
obtain a good working knowledge of the subjects treated in
the shortest time and in the most direct manner possible.

• • •

111

Iv PREFACE

In nicctinc: these requirements, we have produced a set of
books that in many respects, and particularly in the general
plim followed, i'lre absolutely unique. In the majority of
Miil)jei'ts treated the knowledge of mathematics required is
limiti»<I to the simplest principles of arithmetic and mensu-
ration, and in no case is any greater knowledge of mathe-
tuaticH needed than the simplest elementary principles of
al^obra, geometry, and trigonometry, with a thorough,
practical aaiuaintance with the use of the logarithmic table.
To otToct this result, derivations of rules and formulas are
omittoili but thorough and complete instructions are given
tv^iU'ding how» when, and under what circumstances any
particular rule, fonnula. or process should be applied; and
whotu^vor possible one or more examples, such as would be
hkc^v U^ arise in actual practice — together with their solu-
tiotitiC ^icri" ^.rvVn'.ijj rthi5tr*jto and explain its application.

lu piV4MnA>: titost^.tcxibooks, it has been our constant

env5ca\KV\^^ VjiwXTlfu:- matter from the student's standpoint,

^ttut :*5 i;^\i;Vvr'tt:a"cipatc ovorvthing that would cause him

*/•"•**"•*«« •
t'v.iV'c *'T^^ V?;Vt^5t iwins have been taken to avoid and

vvvv: .riY Av.vt alVa:*.tbij:uous expressions — both those due

:o :,i;'.':v :>.o:v^r:c ,;!:v: :hv>so vh:e to ir.sufnciency of sraietnent

sV ov.i\^**^' * ^^> *-^" *^^>' ^^-^y *-^ r::.ike a statement,

>X'** t* t" *** ^"^ * * <.^»»'-»\* • ,%•» i**r^ :'*' •< '.^ .''V-*- "J -^« ■••— --Y* t'\'r o

\ . ..i^^ I >v - ■ ■>»x ,.x «,,.* .«, ...««>m..\. .>...> ».t*^ ^^^T.^ hixru

, VV • . » X » •» ■• X X X-.X...> V. «..* a^^... .^^wi, ^» \.»^ CV

X ^- X>« x^ IX -vv -. ,.>xN. .-,x ^ ,> •'...^_ -v -._. w^:>l

^ *,^ V, -x^ x» x^- .^ .... ^. --^ .^^w— _ •. ^w \m

..■». . ..• »xx »• • ■«..^. ■.'^•"■x"", "■-■ "^J "•■J ;"ii— ".c— -*

X ^^«. _ xX.*x .^xx«.:~x^ ■.^». >_ ^ ^ w «- ^ _ mAu^

*• X X ■ "i " X X. ■ ■x.x """"** ■"■■■" - JX.*"

:-r'i i-e

PREFACE V

indexes are so full and complete, that it can at once be
made available to the reader. The numerous examples and
explanatory remarks, together with the absence of long:
demonstrations and abstruse mathematical calculations, are
of great assistance in helping one select the proper for-
mula, method, or process and in teaching him how and
when it should be used.'

In the first two sections of this volume are described
carbureters and electric-ignition devices used in automobile,
marine, and stationary gas engines. In the third section are
described transmission gears, differentials, clutches, revers-
ing gears, etc. Under power-gas producers are treated the
construction and operation of generators and of the purify-
ing devices used in connection with producer plants, as
well as cleaning devices employed with blast-furnace gas.
In the next three sections are treated the management of
automobile, marine, and stationary gas engines, including
their installation, starting, stopping, and c^re. Under the
head of troubles and remedies are considered the various
troubles encountered in the operation of gas engines,
together with their causes and remedies. In the section on
power determinations are taken up the methods of deter-
mining the power of an engine by means of the indicator,
the brake, or by approximate formulas. The entire volume
is exceedingly practical and valuable to all interested in gas
engines.

The method of numbering the pages, cuts, articles, etc. is
such that each subject or part, when the subject is divided
into two or more parts, is complete in itself; hence, in order
to make the index intelligible, it was necessary to give each
subject or part a number. This number is placed at the top
of each page, on the headline, opposite the page number;
and to distinguish it from the page number it is preceded by
the printer's section mark (§). Consequently, a reference
such as § 16, page 26, will be readily found by looking along
the inside edges of the headlines until §16 is found, and
then through §16 until page 26 is found.

International Textbook Company

• 4

CONTENTS

Carbureters Section Page

Gaseous Mixtures for Gas Engines ... 17 1

Explosion of Gases 17 1

Gas and Air Mixing 17 10

Carburization 17 14

Types of Carbureters 17 15

Stationary-Engine Carbureters 17 19

Automobile and Marine Engine Carbu-
reters 17 27

Carbureter Adjustment 17 45

Electric Ignition Devices

Make-and-Break Ignition 18 1

Jump-Spark Ignition 18 7

Primary Batteries 18 10

Care of Primary Batteries 18 11

Secondary, or Storage, Batteries 18 13

Care of Storage Batteries 18 14

Construction and Operation of Spark Coils 18 24

Care of Spark Coils 18 29

Types of Spark Plugs 18 31

Auxiliary Spark Gap 18 35

Construction and Operation of Timers . . 18 37

Construction and Operation of Distributors 18 41

Ignition Generators 18 45

Magnetos 18 48

Care of Dynamos and Magnetos 18 59

Switches 18 60

Make-and-Break Wiring 18 65

•• •
111

iv CONTENTS

Electric Ignition Devices — Continued Section Paj^e

Jump-Spark Wiring 18 68

Ignition Wire Cable 18 69

Automobile and Marine Engine Auxiliaries

Speed-Changing Systems 19 1

Sliding-Gear Transmission System ... 19 2

Individual-Clutch Transmission System . 19 7

Planetary Transmission System ..... 19 10

Reversing Gears 19 12

Principles of Operation of Differential

Gears 19 15

Spur-Gear Differential 19 15

Bevel-Gear Differential 19 16

Couplings 19 17

Clutches 19 19

Brakes 19 23

Hand Starter for Automobiles 19 24

Automatic Starters for Automobiles ... 19 25

Marine-Engine Starters 19 26

Automobile Governors 19 28

Marine-Engine Governors 19 32

Marine-Engine Water-Cooling System . . 19 33

Automobile-Engine Water-Cooling System 19 34

Radiators 19 37

Circulating Pumps 19 39

Mufflers 19 42

Screw Propellers 19 45

Power-Gas Producers

Classification of Producers 20 1

Pressure Gas Producers 20 4

Suction Gas Producers 20 6

Large-Capacity Producer 20 11

Combined Producer and Evaporator ... 20 13

Down-Draft Producer 20 16

Preparing Producers for Operation .... 20 19

Lining the Producer 20 20

Filling the Scrubber 20 22

CONTENTS V

Power-Gas Producers — Continued Section Page

Pipe Connections 20 23

Testing for Leaks 20 24

Starting the Producer 20 25

Firing the Producer 20 27

Stopping the Producer Plant 20 28

Restarting the Producer 20 29

Cleaning the Pipe Connections 20 29

Operation of Pressure Producers .... 20 30

Blast-Furnace Gas for Gas Engines ... 20 31

Cleaning Blast-Furnace Gas 20 33

Management of Automobile Engines

Inspection, and Location of Faults ... 21 1

Care of the Engines 21 12

Starting and Stopping 21 15

Timing the Valves 21 17

Retiming the Ignition 21 19

Replacing Exhaust- Valve Keys 21 20

Making Valve-Stem Keys 21 21

Taking Off and Replacing Cylinders ... 21 21
Scraping Carbon from Combustion Cham-
ber 21 22

Arrangement of Engine and Auxiliaries . 21 24

Cold- Weather Hints 21 26

Gasoline-Handling Precautions 21 28

Management of Marine Gas Engines

Location of Engine and Auxiliaries ... 22 1

Piping 22 10

Gasoline Tanks 22 IG

Starting, Running, and Stopping .... 22 21

Care and Repair of Engine 22 35

Laying Up the Engine 22 36

Tools and Repair Parts 22 37

Management of Stationary Gas Engines

Selection of Engine 23 1

Examination of Engine 23 2

tJ^i

Managexext of Stationary Gas Engines —

k/^ Secticm Page

Liian of En^^ine 23 4

FocscAtion 23 4

Piping Svsiem 23 10

Cooling STsiem 23 19

Assembling Engine and Ac^nstmeni of

Fins 23 23

Igniiic^n System 23 29

Siirrlng ihe Engine 23 32

Cir« o: Engine Parts 23 41

Igniter 23 41

Fcj^^e: VilTCs 23 42

Ois-C-vrk ..... ... 23 43

LVv-m.r 23 44

S:u.r.-7.i r^\-i.>e> .23 45

Lnrr.ci::c^ lVv-:v>?> . 23 47

x.-^nv.ne .^: MjL::.iier..en: . . 2o 50

K;;v:rs vNr Rvvftifs

-N._ » V V..-^ » . . V ... «....^ — ^ C*

«•. «. ^*. «... i.^^.v ^^ ^^ mmf W

V *.*. A.,. x*..>- C . . -3^ ^T \>%M

- . . .. C* - rt •

, . . ; > «.-e o-i

\ •

£4 36

« V

:t 40

44
4-^

CONTENTS vii

Troubles and Remedies — Continued Section Page

Coil Derangements 24 49

Wiring Troubles 24 50

Timer Troubles 24 53

Clogged Muffler 24 54

Gasoline Leaks .24 55

Water in Exhaust Pipe or Muffler .... 24 55

Water in Engine Cylinder 24 56

Failure to Govern 24 57

Refitting Piston and Piston Rings .... 24 58

Repairing Cracked Water-jacket .... 24 60

Repairing Broken Engine Bed 24 63

Regrinding Valves 24 64

Renewing Babbitt-Metal Liners 24 67

Packing Renewals 24 68

Power Determinations

Object of Engine Testing 25 1

Apparatus Used in Testing 25 2

Method of Making Engine Tests .... 25 19

Reports of Tests 25 22

Horsepower Calculations 25 27

Heat Losses 25 39

Indicator Diagrams 25 41

Shop Tests 25 46

Efficiency 25 48

INDEX

Note. — All items in this index refer first to the section and then to the page of the sccti >\\
Thus. "Ammeter, {18, pll" means that ammeter will be found on page 11 uf section 18.

Adjusting parts, Assembling stationary gas

engines and, (23, p23.
Adjustment. Carbureter, §17, p45.
Coil vibrator out of, {24, p49.
of ignition devices. 123, p34.
of lubricators. (23, p32.
of new automobile- or marine-engine car-
bureters, 517, p47.
jiir gap. Length of. {18. p35.

in explosive mixtures. Proportion of gas

and. 517, p8.
inlet. Carbureter with hit-or-miss governed,

117, p22
inlet controlled by throttle, Carbureters

with. 517, p39.
-mixing chamber. Gas and, (17, plO.
required for gas engine. Volume of, {25,
p24.
Alden dynamometer, $25, p5.
Alternating current in charging storage bat-
teries. Use of, 5I8, pl4.
Ammeter, 518, pll.
Amsler planimeter, (25. p29.
Apparent slip of propeller, 119, p52.
Area of propeller blades. Developed, $19, p52.

of propeller blades. Projected, §19, p52.
Arrangement of automobile engines and

auxiliaries, $21, p24.
Assembling governing mechanism. {23. p26.
stationary gas engines and adjusting parts.
123, p23.
Automatic float -feed carbureters. 517, p34.
inlet valve. Excessive lift of, 524, p23.
inlet-valve springs. Effect of unequal ten-
sion of, 524. p23.
starters for automobiles. 519, p25.
Automobile battery switch, 518, p>62.
-engine carbureter, (17, p27.
•engine carbureters. Regulation of, 517,
p28.

Automobile — (Continued)

-engine cooling, 519, p34.

-engine governors, 519, p28.

engines and auxiliaries. Arrangement of,
521. p24.

engines, Care of. 521, pl2.

engines. Inspection of, 521, pi.

engines. Location of faults in, 521, pi.

engines. Retiming the ignition of. 521, pi 9.

engines. Starting and stopping, 521, pl5.

engines. Timing valves of, 521, pi 7.

or marine-engine carbureters. Adjustment
of new, 517, p47.

speed change gear, 519. pi.
Automobiles. Automatic starters for, 519. p25.

Hand starter for, 519, p24.

Non-freezing solution for, 521, p26.
Auxiliaries, Arrangement of automobile en-
gines and, 521. p24.

Location of marine engine and, 522, pi.
Auxiliary spark gap, 518, p35.

Babbitt-metal liners. Renewing, '524, p67.

Back firing, 524. p38.

Bag, Gas. 517, pl2.

Band clutch, 519, p21.

Batteries, Care of primary, 518, pll.

Care of storage, 518, pl4.

Charging storage, 518, pi 6.

Electrolyte for storage, 518, pl4.

Laying up storage, 518, p21.

Primary, 5 18. plO.

Renewing storage, 518, p23.

Secondary or storage, 518, pl3.

Testing. 521. p9; 524, p45.

Testing storage. 518, p20.

Use of alternating current in charging
storage, 518, pl4.

Wiring connections for charging st(.»ragt ,
§18. pl7.

INDEX

Battery and spark oofl. Installation ci, {23.
p29.

connectors, flS, pl2.

power. Reserve, 124. p45.

switch. Automobile, §18, p62

troubles, (24, p44.

weak, (24, p44.
Baumd hydrometer. (18. pl5.
Bearings, Inspection of. 121, p3.

Lack of oil in, (24, p25.
Bevel-gear differential, $19. pi 6.
Blades, Crowning surface of propeller. (19, p52.

Cutting edge of propeller, §19, p52.

Developed area of projieller, (19, p52.

Driving surface of propeller, (19, p62.

Projected area of propeller, (19, i>62.
Blast-fumace gas, Geaning, §20, p33.

-furnace gas. Composition of, §20, p31.

-furnace gas for gas engines, §20, p31.
Bolts, Engine foundation, §23, p5.
Brake horsepower, §25, p2.

Prony §25. p2.

Rope, §25 p4.
Brakes §19. p22.

Break m primary wiring circuit, §24, p50.
Broken engine bed. Repairing. §24. p63.

exhaust-valve spring. Weak or, §24, p24.

exhaust-valve stem or key, §24, p24.

inlet-valve spring, Weak or, §24, p22.

inlet-valve stem or key, §24, p24.

piston rings. Sticking and, §24, pl6.

secondary wiring cable, §24, p51.

spark-plug porcelain, §24, p45.

Cable, Broken secondary wiring, §24, p51.

Grounded secondary wiring, §24, p61.

Ignition wire, §18, p69.
Calculations, Horsepower. §25, p27.
Cams, Slipped valve, §24, p24.
Carbon from combustion chamber, Scraping,

§21.p22.
Carbureter adjustment, §17, p46.

Automobile-engine, §17, p27.

Definition of, §17, pl5.

Dirt in. §24, p33.

Disturbances, §24, p30.

Float too heavy, §24, p35.

Float too high, §24. p34.

Float too light or adjusted too few, (24. p35.

Flooding of, §24. p31.

Kerosene-engine, §17, p26.

Testing, §21, p2.

with hit-or-miss governed air inlet, §17. p23.

with hit-or-miss governed gasoline inlet.
§17, p25J.

with water-spray attachment, §17. p20.

Carbureters, Adhistment of xww antonBoi3ilB>
or marine-engine, §17, p47.

Advantage of spray. §17, pl8.

Automatic float-feed. §17. p84.

Central-feed, §17, p42.

Classification of, §17, pl5.

Filtering, §17, pl5.

Float-feed, §17, p32.

Objections to surface and filterins^ (17.
pl7.

Regulation of automobile-engine, |17» p28.

Spray, §17, pl6.

Stationary-engine, §17, pl9.

Surface, §17, pl5.

with air inlet controlled by throfckle, §17,
p39.
Carburization, §17. pi 4.
Care and management of stationary su
engines. §23, p41.

and repair of marine engines. §22, p35.

of automobile engines, §21 , pl2.

of dynamos and magnetos. §18, p59.

of primary batteries, §18, pll.

of spark coils. §18, p29.

of storage batteries, §18. pl4.
Causes of misfiring, §24, p3.

of preignition, §24, p40.

of refusal to start or sudden stoppase of
engine, §24. p2.

of slowing-down troubles with marine
engines. §24, p5.

of weak explosions, §24. p4.
Central -feed carbureters, §17, p42.
Centrifugal gas-cleaning plant, §20, p34.
Charge, Definition of. §17, p2.

in cylinders. Order of firing, §18, p39.

Ovcrrich mixture or, §24. p30.

Weak mixture or, §24, p32.
Charging storage batteries, §18. pl6.

storage batteries. Use of alternating cxtrrent
in, §18. pl4.

storage batteries, Wiring connections for,
§18, pl7.
Circuit, Break in primary wiring, §24, pSO.

Short, §24, p48.
CSrctdating pumps. Types of water, (19, j>39.
Circulation of cooling water. Obstructed, (24,
p28.

pressure gauge. Water, §19. p42.

tell-tale. Water, §19. p42.
Classification of carbureters, §17, pl5.

of gas producers §20, pi.
Cleaning blast-fumace gas, §20, p33.

pipe connections to suction gas producer
§20, p29.

plant. Centrifugal gas. §20, p34.

plant with notary washer. Gas, §20. p33.

INDEX

Oearanoe, Finding percentage oC, t25, p84.
Qogged mufBer, §24, p54.
Qutch, Band, §19, p21.

Disk. §19. p22.

Friction ring, §19, p21.

transmission system, Individual, §19. p7.
Clutches. Cone, 119. pl9.
Cock. Care of gas-, 123, p43.

Location of sea. 122. pl4.
Coil condenser. Defective. (24, p49.

connections. Spark-, flS, p25.

derangements. 124, p49.

Installation of battery and sx>ark, |23, p29.

Short-circuited. 124. p50.

trembler, Spark-, (18, pp8. 28.

vibrator out of adjustment. (24, p49.
Coils. Care of spark. (18, p29.

Construction and operation of spark, (18,
p24.
Cold-weather hints, (21, p26.
Combustion chamber. Scraping carbon from.
|21,p22.

knock, (24, pll.
Commutators or distributors. Secondary, (18,
p41.

Timers or primary. (18. p37.
Comparison of suction and pressure gas

producers. (20. p6.
Compensating gear. Equalizing or, (19. pI5
Composition of blast-furnace gas. (20, p31.
Compound pitch. (19. p47.
Compression and mean effective pressures.
(25. p38.

coupling, (19. pl8.

relief and spark retardation in marine
engines, (22. p29.
Condenser, Defective coil, (24, p49.
Cone clutches. (19. pl9.
Connecting-rod. Assembling piston and, (23

p26.
Connections. Electrical. (23. p31.

for charging storage batteries. Wiring, (18.
pl7.

Loose electrical, (24. p52.

Spark-coil. (18. p25.

Testing electrical. §23. p31.

to gas producer. Pipe. (20. p23.

to suction gas producer. Cleaning pipe, (20.
p29.
Connectors. Battery. (18. pl2.
Construction and operation of spark coils,
(18. p24.

of large suction gas producer. (20. pll.

of small suction gas producer. (20. p8.
Consumption, Gas. (25. p26.
Contact point. Dirty. (24, p49.

Short-time, (24, p48.

Contacts, Poor electrical, (24, p47.

roughened by sparking. Timer, (24. p53.
Converter. Mercury-vapor, (18, pl4.
Cooling and muffling devices, (19* p33.

^Automobile-engine, (19, p34.

by steady water supply, (23, p21.

Marine-engine. (19. p33.

radiators. Types of water, (19, p37.

system for stationary gas engines. Water
(23. pl9.

system troubles. Water, (24, p27.

Tank system of. (23. pl9.

water. Lack of. (24. p27.

water. Obstructed circulation of. (24. i>27

-water tank. (25. pl5.

water. Temperatixre of. (23. pl9.
Counter, Revolution, (25. pl7.
Coupling. Compression, (19. pl8.

Crab-claw, (19, pl9.
Couplings. Plain. (19. pl7.

Universal, (19. pl9.
Crab-claw coupling. (19. pl9.
Cracked water-jacket. Repairing, (24, p60
Crank-case, Level of oil in, (23. p48.
Crowning surface of propeller blades. (10

p52.
Current leakage. (24. p44.
Cutting edge of propeller blade, (19. p52.
Cylinder and piston repair work, (24. p58.

oil. Lack of, (24. p25.

packing troubles. (24. pl8.

Water in engine. (24. p56.
Cylinders, Improper oil in, (24, p2fi.

Order of firing charge in, (18. p39.

Taking off and replacing, (21, p21.

Scored and leaky, (24. pl2.

Decreasing pitch. (19, p47.
Defective coil condenser. (24. p49.
Delivered horsepower. (25. p2.
Deposits in water-jacket. (23, p21.
Derangements, Coil. (24, p49.
Detonation, (17. pi.

Developed area of propeller blades, (19, p52
Diagrams, Explosive-mucturc pressure. (17
p5.

Indicator, (25, p41.
Differential, Bevel-gear, (19. pi 6.

gears. Operation of, (19. pl5.

Spur-gear, (19. pl5.
Dirt in carbureter, (24, p33.

or waste in gasoline pipe. (24. p88.
Dirty contact point, (24, p49.

radiator, §24. p29.
Disk clutch, (19, p22.
Disorders, Spark-plug, (24, p45.

XII

INDEX

Displacement. Piston, (25, p22.
Distributors, Secondary commutatorB or, (18,

p41.
Down-draft gas producer, 120. pl5.
Driving surface of propeller blades. {19.

p52.
Dynamo as a dynamometer, 125, p7.

-electric ignition generators, §18. p45.
Dynamometer, Alden, (25, p5.

Dynamo as a, $25, p7.
Dynamos and magnetos, Care of, (18, p50.

Effect of unequal tension of automatic inlet-
valve springs, $24. p23^
Effective pressure. Mean, $25, p34.
Efficiency, Engine, (25, p48.

Mechanical, $25, p49.

Thermal, $26, p48.
Electrical connections, $23, p30.

connections. Loose, $24, p52.

connections. Testing. $23, p31.

contacts, Poor, §24, p47.
Electrolyte for storage batteries. $18, pi 4.
Engine and auxiliaries, Location uf marine,
$22, pi.

bed. Repairing broken, $24, p(i3.

Causes of refusal to start ur of sudden
stoppage of, 524, p2.

cooling, Automobile-. $19, p34.

cooling, Marine-, 519, p33.

cylinder. Water in, §24, p56.

efficiency, $25, p48.

exhaust. Piping marine-, $22, pl4.

-foundation bolts. $23, p5.

Foundation for marine, $22, p3.

Foundation of stationary gas, §23, p4.

-ff)un<lation templet, §23, p4.

foundation. Timber. §23, p8.

governors, Automobile-, §11), p29.

governors, Marine-, $19, p32.

indicator. Gas-, $25, p7.

ignition mechanism, Marine-, $18, i>4.

installation, Marine-. i'J'2, pi.

manaKenu-nt, Routine of stationary ^jas-,
§23. poO.

«il>oration, Marine-. §22, X)21.

starters, Marine-, §19, p20.

starting and running difficulties, Gas, §24,

Pl.
test, Log of Ka<.-, §2"), p20.
test. Method of making Has-, §25, pl9.
test. Report of Has-, §25, p22.
testing. Object of gas . §25, j)].
to bed. Fastening marine, §22, p8.
vibration. Prevention of. §23, p7.
Volume of air required for gas, §25, p24.

Engines and adjusting parts. Assembling stir
tionary gas, (23, p23.

and auxiliaries. Arrangement of automo>
bile. (21. p24.

Blast-furnace gas for gas, (20. p31.

Care and management of stationary gas.
(23, p41.

Care and repair of marine, (22, p35.

Care of autoniobile. (21. pl2.

Causes of slowing-down troubles with
marine, $24, ]>5.

Compression relief and spark retardation in
marine, (22. p29.

Examination of stationary gas, (23 p2.

Gaseous mixtures for gas, (17, pl.

Gasoline piping for marine, (22, plO.

Inspection of automobile. (21, pl.

Irregular running of. marine, (24, p6.

Laying up marine. $22, p36.

Location of faults in automobile, (21, pl.

Location of stationary gas, (23. p4.

on floor. Supporting, $23, p8.

Piping system of stationary gas. $23, plO.

Retiming the ignition of automobile. |21»
pl9.

Reversing gear for marine, $19, pl2.

Selection of stationary gas, $23, pl.

Sizes of piping for gas. §23, pll.

Starting and stopping automobile. (21 , pI5.

Starting, running, and stopping marine.
$22, p21.

Starting stationary gas, $23, pp32, 50.

Stopping stationary gas, $23, p51.

Timing valves of automobile, §21, pl7.

Use of starting bar for marine, $22, p27.

Use of starting cranks for marine, (22, p26.

Water-cooling system for stationary gas,
§23. pl9.

Water piping for marine, $22, pl2.
Equalizing or compensating gear, $19, pl5.
Evaporator, Combined i>roducer and, $20,

pl3.
Examination of stationary' gas engines, $23,

p2.
Excessive lift of automatic inlet valve, (24,

p23.
Exhaust pijK.' or muffier, Water in, $24, p55.

piping. §23, pl3.

Piping marine-engine, §22, pl4.

Underwater. §19, p33.

-valve keys, Replacing. §21, p20.

-valve spring, Weak or broken, §24, p24.

-valve stem or key. T3roken, $24, p24.

valves, Leaky inlet and. §24, p20.
Expanding pitch, §19. p47.
P^xplosion of gases. §17, i)l.
Explosions, Causes ut weak, §24, p4.

INDEX

Bxplorive gaseous mixture, {17. pi.
gaseous mixtures, Measuring changes cf

pressive in. §17, p3.
•mixture pressure diagrams, 117, p5.
mixtures. Proportion of gas and air in, (17,

P8.
mixtures. Rate of fall of pressure in, (17,

p6.
mixtures. Rate of flame propagation in, 117,

plO.

Failure to govern. §24, p57.

Pa<^ning marine engine to bed, (22, p8.

Faults in automobile engines. Location of,

«21.pl.
Filling pipes and vents to tanks! Gasoline, (22,

pl8.
Filter. Gasoline. 123. pl8.
Filtering carbureters, §17. pl5.

carbureters, Objections to surface and, §17.
pl7.
Firing charge in cylinders. Order of, §18. p39.

suction gas producer. §20, p27.
Flame propagation. §17. p2.

propagation in explosive mixtures. Rate of,
§17. plO.
Float-feed carbureters, §17. p32.

-feed carbureters, Automatic. §17, p34.

too heavy. Carbureter. §24. p35.

too high. Carbureter. §24. p34.

too light or adjusted too low, Carbureter
§24. p35.

^'alve. Leaky carbureter, §24. p34.
Flooding of carbureter, §24. p31.
Flywheel. Assembling shaft and. §23, p23.
Formula. Horsepower, §25, p37.
Foundation bolts. Engine-. §23, p5.

for marine engine, §22. p3.

of stationary gas engine. J23, p4,

templet. Engine-, §23. p4.

Timber engine, §23, p8.
Foundations for gas producers, §20, pl9
Friction-ring clutch, §19. p21.
Fuel troubles, §24 p36.

Gap. Auxiliary spark. §18. p35.

Length of air. §18, p35.

Length of spark. §21, p8.

Safety spark. §18, p27.
Gas and air in explosive mixtures. Propor-
tions ot §17. p8.

and air-mixing chamber. §17, plO.

bag. §17. pl2.

Qeaning blast-ftunace. §20. p33.

•cleaning plant. Centrifugal. §20, p34.

-cleaning plant with rotary washer. §20, p33.

Gas— (Continued)
-cock. Care of, §23, p43.
Composition of blast-furnace, §20, p31.
consumption. §25. p26.
engine. Foundation of stationary. §23. p4.
-engine indicator, §25, p7.
•engine management. Routine of stationary.

§23. p50.
-engine starting and running difficulties

§24. pi.
•engine test, Log of. §25, p20.
-engine test, Method of making, §25. pl'J.
•engine test. Report of, §2.'>, p22.
-engine testing, Object of. §25. pi.
engine, Volume of air required for, §25, i)24.
engines and adjusting parts. Assembling;

stationary. §23, p23.
enj^ines. Blast-furnace gas for, §20, p31.
engines. Examination of stationary, §23, p2.
engines, Gaseous mixtures for. §17, pi.
engines, Location of stationary, §23. p4.
engines. Management and care of stationary,

§23. p41.
engines, Piping system of stationary, §23,

plO.
Engines, Selection of stationary, §23, pi.
engines, Sizes of piping for, §23, pll.
engines, Starting stationary, §23, pi 32, 50.
engines. Stopping stationary, §23, p51.
engines. Water-cooling system for station-
ary, §23, pl9.
measurement. §25, pl5.
meter, §23. pl3.
meters. Sizes of. §23. pl3.
Piping for natural. §23, pl3.
pressure. Measurement of. §25, p25.
pressure. Regulating, §23, p38.
•pressure regulator, §23, pi 2.
Process of manufacturing producer. }20,

p2.
producer. Cleaning pipe connections tn

suction, §20, p29.
producer. Construction of large suction,

§20, pll.
producer, Construction of small suction. §?0.

p8.
producer. Down-draft. §20. pl6.
producer. Firing suction, §20, i)27.
producer. Lining the. §20. p20.
producer. Pipe connections to. §20, p23
producer, Restarting suction, §20. p2'J.
producer. Starting suction, §20, ppll, 25.

28.
producers. Gassification of. §20, pi.
producers. Comparison of suction and pres

sure, §20, p6.
producers. Foundations for, §20, plO.

XIV

INDEX

Gas — { Continued)

producers, Mana^ment of, 130, pl9.

pfoducers. Operation of pressure. {20. p30.

producers. Operation cf suction. §20 p25.

producers. Pressure. f20. p4.

producers. Suction. (20. p6.

-regulating floor. il7. pll.
Gaseous niixture. Explosive. §17. pi.

TTUxtures tor gas engines. §17, pi.

TT.ixtures. Measuring changes of presstire in
explosive. §17. p3.
Oases. Explosion of. §17. pi.
Gasoline filling pipes and vents to tanks. f22.

rJter. %23. pl8.

-handling precautions. §21. p2S.

inlet. Carbureter with hit-or-n:iss governed.
§l7.p22.

leaks. §24. pS5.

pipe. Dirt or waste in. §24. p33.

Piping for. §23. pi 7.

piping frr riarine engines. §22. plO.

p-.irr.p. Care cf. §23. f44.

Stale. §24. p36.

tar.i. §22. pl6.

Water in. §24. poO. ,

Gauire. Siphcr:. §2o. p2o.

U. j2o. p2,>

Water. 52o p25.

Witercirculaticn pressure. §19. p42.
Ge^r .\-.:t v^- bile speed -char .re. SlV*. pi.

viinervr.t'-il B«:vel. §1*.*. pl',«

dirc:i?r.t-\l. Sp-.:r. Jl;>. p!5

E ;-.LaI::ir.j: -- . ntpor.satir.;:. §1'.^. pl.'^

f r rt'.arir.e t'r.^-ire>. Reverv^rc. §1^?. pi 2.

J- - ■■J' ■ » •• ■ i^f'- •

-<'-.a:t. AN^tr::': ".•v.^ v.\lvo. §23. p26

trar «-:*.•<>• ^n sy>re'r.. Sliding. §1V». p2.
i'lears. Ch^r.i:: r. .: .".irfervnti.*! §19. plo.
irt r.€rx'. r* . D vr a • • : • o'.c ct ric i<:r.:t :o r. . § 1 S . ;^4 '• .
Crverr.. Failv.rv t . §24. pC»7.
G: vtrr.ir.^ .:evuY>. S:art:n^ ar..l. §19. p24

"•t.Var. '..>—.. .X^.^'vV*.:::/. §2-^^. p2tv
Cr-vcrr.. r. i.\ir\ : $2.%. p4-i.
Gr-.trr. r*.. A-..: :r V-'.c *r.s'r.. . $10. p2>.

Ma rr r.e ■ c : v : ■:: J '. \» r :i2

J24.roi.
vr'-ir.. '.«■.: ><:.■ 'n.l.ir\ wi^.tv ^a\'lo. J24. :.v»l.

Hard <tartor • " .»■. *. •'r.b\\'<. $r.». :^2l.
Hat. he: ;'a:v."-.:i '.'$_.*>. -vl

Hf^t 1 >.;<'':. $2.'. '.nI;*

-tcnsis-r. s-w::^:., §1S. ;<H.

Hints. Cold-weather. 121. p26.
Uit-or-ndsB governed air inlet. Carbureter
with. §17. p23.

-or-nuss go^remed gawnKne inlet. Ckiboreter
with. §17. p22.
Horsepower. Brake. §25. p2.

calculations. §25. p27.

DeUvered. §25. p2.

tjrmuia. §25. p37.

Indicated. §25. p2.
Hydrometer. Baurae. f 18, pl5.

Igniter. Care of. §23. pll.

Examination of \-alvies and. §23. p33.

plug, §lS. p3.

troubles. Make and-break. §24. p47.
Ignition. Dennition of. §17. p2.

de\-ice*. Ad-ustnaent of. §23, p34.

generators. Dyaareo-dectric, §18. p45.

Jun^p-spark. § IS. p7.

niagnetos, §1S. p47.

Make-and-break. §18. pi.

r:Tech.ani5rr.. Sfarine-engine. §18, p4.

of a-Jtr mobile engines. Retiming §21, plft

plugs. §23. p30.

systerr.. Inspection of, §21, p7.

Titre,:. §17. p2.

Tin-.-nfe- the. §23. pW.

wire cable. §1S. p69.
I:vpr."per oil in cylinders §24. p26.
Ino.-»rrec: timing. §24. p54.
Increasing ;:itch. §19. p47.
Indicated h-"rsep«"wer. §25. p2.
Indicator diagrams. §25. p41.

Ga*-eng:r.e, §25. p7.

Reviucirg :-:.ti. n.-. §25. pl2.

Speed. §2o. pl7.
l::.Mv-;iual-. I ■-•.>: 1: * ransmission system. §19,

lr.^.Arrr-jL*i.r.. FKzration of. §17, p2.

lr.le: JLr.i cvha.:>t %-a!ves. Leaky. §24. p20.

valve. E\v-e>-<:ve r.ft of automatic, §24.
p2:?.

-valve rr.rc. Weak or bmken. §24. p22.

-valve <rrir.c< ErTect of unequal tension of
a-::. -at::. §24. p23.

-va. e <tc"- . r key. Bn-ken. §24. p24.

N-ulvf": Ir.>iv.-.:. r. . f. §21. p5.
l">:v.r-. r. . : a-.;:, r-.-bile engines, §21. pi.

v: Nartr.j:^. §21. p>3.

\^* icr.-.:: :; >y>:er:'. §21. p7.

.■:•.:■.'.: '..\lves §21 po.

. : '•.■.V-^..a:-.r.^ <v>ter'.. §21, p6.
• \^.v:<.' ,- ■■'".'.•'^ >y<:tfr::s. §21. pll
l*'>:..*!.ir' V MA">.o-<r..sir.e. §22. pi.
lrrvf;,."..\r r.-.-r-.: j . :' -Tiarlne engines, §24, p6

INDEX

)eposits in water-, (23, p21.

muffler, (19. p44.
liversal, (19. pl9.
ark Ignidon, (18, p7.

wiring, (18. p68.

^-engine carbureter, (17, p25.

)ken exhaust-valve stem or, §24, p24.

n inlet-valve stem or, (24, p24.

aldng valve-stem, (21, p21.

nns exhaust- valve, (21, p20.

•itches. (18, p60.

Combustion, (24, pll.

g due to preignition, (24, pl2.

nding. (24, p8.

cooling water, (24, p27.

nder oil, (24. p25.

n bearings. (24, p25.

ction gas producer. Construction of,

pll.

p marine engines, (22, p36.

rage batteries, (18, p21.

Current, (24, p44.
asoline, (24, p55.
I producer for, (20, p24.
rburetef float valve, (24, p34.
;rs. Scored and, (24, pl2.
id exhaust valves, (24. p20.
)lug, §24. p47.

Regrinding. (24, p21.
[ spark gap. (21. p8.
lark advance, (18, p38.
itomatic inlet valve, Excessive, (24,

lewing Babbitt metal. §24. p67.

e gas producer, §20, p20.

ot faults in automobile engines. §21,

onary gas engines, (23, p4.
s-engine test, §25, p20.
rtrical connections. §24, p52.
eat. §25. p39.
on magnetos, §18, p49.
ig devices. Care of, §23, p47
Inspection of, §21, p6.
)n troubles, §24. p25.
rs, Adjustment ot, §23, p32.
nent of, §23. p29.

Care of dynamos and §18. p59.
nsion, §18. p51.
1. §18. p47.
ision. (18. p49.

B(ake-and-break igniter troubles (24, p47.

-and-break ignition, (18. pi.

•cmd-break wiring, (18, p65.
BCaking valve -stem keys, (21, p21.
Management of gas producers, (20, pl9.

of stationary gas engines. Care and, (23,
p41.
Marine engine and auxiliaries, Location of.
(22. pi.

-engine carbureters, Adjustment of new
automobile- or, (17, p47.

-engine cooling, (19, p33.

•engine exhaust piping. (22, pl4.

engine, Foimdation for, (22, p3.

-engine governors, (19, p32.

-engine ignition mechanism, (18, p4.

-engine installation, (22, pi.

•engine operation, (22. p21.

•engine starters. (19. p26.

engine to bed. Fastening, (22, p8.

engines. Care and repair of. (22, p35.

engines. Causes of slowing-down troubles
with. (24. p5.

engines. Compression relief and spark
retardation in, §22, p29.

engines. Gasoline piping for. (22. plO.

engines. Irregular nmning of, (24, p6.

engines. Laying up. (22, p36.

engines. Reversing gear for, (19, pl2.

engines, Starting, running, and stopping.
(22. p21.

engines. Use of starting bar for, §22. p27.

engines. Use of starting cranks for. §22.
p26.

engines. Water piping for, (22. pl2.
Mean effective pressure, (25,, p34.

effective pressures, Compression and, (25,
p38.

pitch (19, p55.
Measurement. Gas (25, pl5.

of gas pressure, (25. p25.
Measuring changes, of pressure in explosive
gaseous mixtures. §17, p3.

pitch of screw propellen §19, p48.
Mechanical efficiency, §25. i>49.
Mercury- vapor converter, §18. pl4.
Meter. Gas, §23, pl3.
Meters. Sizes of gas. §23, pl3.
Method of making gas-engine test §25. pl9.
Methods of startiiig, §23. p34.
Miscellaneous troubles. §24, p54.
Misfiring. Causes of. §24. p3.
Mixing chamber. Gas- and air-. (17. plO.

valve. (17, pl3.

Explosive gaseous, (17, pi.

pressure diagrams, Explosive. (17, p5.

in starting. Regulation of, §23, p35.

XTI

INDEX

H^xxnnt i'jr 9m cofina^ Ga«oas. |17. pi.
yU%j»irirje[ c^.aa«et *A f>nmr:a^ m ezplosiTe

tiJittrxiA, §17. p3.
Vr'.'^jirfj^jci^ 'A JEW afl<! air m explocive, §17.

'A-
SCA^Ur '^ laH of ;/msore in explcmve, §17.

V.^Ji 'A flarrA {/rvpaipbtion in explosive.

Ml. pIO.
*C ;«i*^. O^MSOtA. 124, ;A4.
> kif*^. |l'^. ji44.
TT^vrr a exhautt pipe or, 124, i>55.
W*-.. f :5r. p44.

U -sf^.if tif'-kef . OxiUng and. (19 p33.

•iV .r^ grxx. P:;,tr./ f',r. |23. pi 3.

•• ,r. /r-^nta-^ v/l-jtk/ji for aut/imobfles, {21 .

''/^/rtri/.t/t'J ciff-ilation <-/£ cooling «-ater. J24.

^/s: xr. r^Arauei. Laiik of f24. p25.

:ft '.rhnk^aM:. Levtl of. {23, i*48.

in '.yitnden. Impr/ijer, §24. p26.

I^.k of olin'Irr. §24. p2.*i.

/,r. pi4t//n%. T'^/ much. |24. p27.
'/;^ratt^/n. Marine -^nifine. |22. p21.

'/f fJiffervirntial Ke^n. fid pl5.

'/f pr«*\*ure f(aA pT'Klu/.crs. §20, p30.

of tfKirk cfAl%, 0>n>truction and. §18, p24.

of «.<jr ti'^n ga« pT'/^lur.ert. f 2f), p2i>.
f >rfU r of f.rin;; * harKc in cylinrSers, {18, r>39.
Ovr-riv h mixture or charKe, §24, p30.

I'a' king r»;tVM*al*, |24, p6S.

tr'«;h!#-s. Cylinder, §24, pl8.
fVr' f-ri'-a^^T of r.l«;aninr:e. Finding, {25 p24.
Pif.ninK pi -U/n rinKs, §24, pi 7.
Pif/*- f onmv lion* to Kas pf/duccrs. §20, p23.

« '#nn#".tions P» s'lction gas pniduter. Clean-
ing. 120. p20.

I>irt or wa*.t<: in gascjline, f24, ii33.
I'tii*'. and vents Vj tanks. Ga valine filling, 122,

pl8.
ViiAtiK. ExlauM. 123, pl3.

for gas engini-s, Sizes of, §23, pll.

for gaviline. f23, pi 7.

for marine enKim'^. Cras/jlinc, {22, plO.

for marine en^im-s, Wat«:r, §22, pi 2.

for natural ^as, |23, pl3.

Marini; i-n^^in*- •xl.aMst, §22, pi 4.

• v.li'iu of -.tati'iiiurv y.u: divines, |23, plO.
finton and » 'irinn ti«){-rod, AsscinblinK, J23,
p2:..

aadpistoo

(^KfAMctment^ |25. pfi3.

Examination of. §23. p33.

repair work. Cylinder aad. |9^ p68b

rings, fanning. 124. pl7.

rings. Refitting pistoii aad, |24. p68.

rings. Sticking and bcvdoen, §24, plft.
Pistons, Too tnach oA 00, ^4, pS7.
Pitch. Compound. }19. x>47.

Decreasing, f 19. p47.

Expanding, f 19. p47

Increasing. 119. p47.

Mean, f 19. pS5.

of screw pTopeOer. }10. p46.

of screw propeller. Measmiiig, |19. |>48L

of screw propeller. Cnifonn, |10. p47.

True. §19. p47.
Plain couplings. §19. pl7.
Planetary transraiasion system |19, plOl
Planimeter. Annler. f25. p39.

Hatchet. f25. p31.
Plug. Igniter, f 18. p3.
Plugs. Ignition. f23. p30.

Requirement of spark, |18, p34.

Spark, f 18. p31.
Poppet valves. Oare of. }23. p42.
Porcelain, Broken qiark-plug. §24. p45.

Soot on spark-plug. f24. p46.
Pounding. Knocking or. }24, p8.
Power. Reserv'e battery. f24, p45.
Precautions. Gasc^ine-handling, |21t p28.
Prcigniiion, {24, pi 2.

Causes of, f24. p40.

Definition of. §24. p40.

Knocking due to. }24, pl2.

Remedies for. f24. p41.
Pressure diagrams. Explosive mixtuvi, |17
p5.

gas producers, (20, p4.

gas producers. Comparison of suction and,
• 520, p6.

gas pn)duccrs. Operation of. §20, p30

gauge. Water-circulation, 119, p42.

in explosive gaseous mixtures. Measuring
chan>fes of, §17. p3.

in explosive mixtures. Rate of fall of, §17^
p6.

Mean efTective, {25, p34.

Measurement of gas, (25, p25.

RcgulatinK gas. J23, p38.

regulator. Gas-, §23, pl2.
Pressures. Qjmpression and mean effective,

J25. p'.iS.
Primary batteries, §18. plO.

l>atl('rics, Care of, §18, pll.

cominutaturs, or tiinerb, §18, 1)37.

INDEX

xvu

PinmuT^Continued)

wiring circuit. Break in, {24, p50.

wiring short circuit or ground in, (24, f>51.
Process of manxifacturing producer gas. (20,

P2.
Producer and evaporator combined, 120, pl3.

Cleaning pipe connections to suction gas,
§20. p29.

Construction of laige suction gas. |20. pll.

Construction of small suction gas. 120, p8.

Down-draft gas, (20, pl6.

Firing suction gas, (20, p27.

for leaks. Testing. (20. p24.

gas. Process of manufacturing, (20, p2.

Lining the g^, (20. p20

Pipe connections to gas, (20. p23.

Restarting suction gas, (20, p29.

Starting suction gas (20, ppll, 25.

Stopping stiction gas, (20, p28.
Producers, Classification of gas, (20, pi.

Comparison of suction and pressure gas
(20, p6.

Foundations for gas, (20, pl9.

Bfanagement of gas, (20, pl9.

Operation of pressure gas, (20, p30.

Operation of suction gas, (20, p25.

Pressure gas, (20» p4.

Suctkin gas, (20, p6.
Projected area of propeller blades, (19, p52.
Prony brake, (25, p2.
Propeller, Apparent slip of, (19, p62.

blades. Crowning surface of, (19, p52.

blsules. Cutting edge of, (19. p52.

blades. Developed area of, (19, p52.

blades, Driving surface of, (19, p52.

blades. Projected area of, (19, p.52.

Measuring pitch of screw. (19, p48.

Pitch of screw, (19, p46.

Slip of, (19. p52.

Slip of screw, (19, p46.

Uniform pitch of screw, (19, i>47.
Propellers, Reversing, (19, p55.

Types of screw, (19, p45.
Proportions of gas and air in explosive mix-
tures, (17, p8.
Pump, Care of gasoline, (23, p44.

Gear, (19, p40.
Pumps, Types of water-circulating, (19, p39.
p3rroroetcr, (25, pl6.

Radiator, Dirty, (24, p29.

Scale or sediment in, (24, p28.
Radiators, Removal of scale from, (19. p30.

Types of water-cooling, (19, p37.
Kate of fall of pressure in explosive mixtures.
(17. p6.

Rate — (Continued)

of flame propagation In exploave mixtures
(i7, plO.
Readings, Temperature. (25, p26.
Reducing motions. Indicator, (25, pl2.
Refitting piston and piston rings, (24, p58.
Regrinding leaky valves, (24, p21.

valves. (24, p64.
Regulating gas pressure, (23, p38.
Regidation of automobile-engine carbureters,
(17, p28.

of mixture in starting, (23, p35.
Regtilator, Gas- pressure, (23, pl2.
Remedies for preignition, (24, p41.

for slowing-down troubles with marine
engines, (24, p6.
Renewals, Packing, (24, p68.
Renewing Babbitt-metal liners, (24, p67.

storage batteries, (18, p23.
Repair of marine engines. Care and, (22, p35.

parts. Tools and, (22, p37.

work. Cylinder and piston. (24, p58.
Repairing broken engine bed, (24, p63

cracked water-jacket, (24, p60.
Repairs, (24. p58.
Report of gas-engine test, (25, p22.
Reserve battery power (24, p45.
Restarting suction gas producer. (20. p29.
Retiming the ignition of automobile engines,

(21, pl9.
Reversing gear for marine engines, (19, pl2.

propellers, (19, p55.
Revolution counter, (25, pl7.
Rings, Pinning piston, (24, pl7.

Refitting piston and piston, (24, p58.

Sticking and broken piston, (24, plG.
Rope brake. (25, p4.
Rotary washer. Gas-cleaning plant with. (20.

p33.
Routine of stationary gas-engine manaffp-

ment, (23, p50.
Running, and stopping marine engines.
Storting, (22, p21.

difficulties. Gas-engine storting and, (24. pi .

Safety spark gap, (18, p27.

Scale from radiators, Removal of, (19, p39.

or sediment in radiator, (24, p28.
Scored and leaky engine cylinders, §24,

pl4.
Screw propeller. Measuring pitch of, (19, p48.

propeller. Pitch of. (19, p46.

propeller. Slip of. (19, p46.

propeller, Unifonn pitch of. (19, p47.

propellers. Types of, (19, p45.
Sea cock. Location of. (22, pl4.

xvin

INDEX

Secrmdary oommtitaton or Sstxibntors, f 18.
p41.

or itongt batteries. flS. pl3.

wiring cable. Broken. f24. p51.

wiring caUe. Grounded. f24. p51.
Sediment in radiator. Scale or. f24. p28.
Selfcctir/n of stationary gas engines. f23. pi.
Shaft and flywheel. Assembling f23. p23.

Assembling valve gear, f23, p26.
Shop tests. f25. p46.
Sb/^irt circuit. §24, p48.

circuit or grotmd in primary wiring, (24,
p51.

•circuited coil 124. p50.

'time cr>ntact. f24, p48.
Siphr/n gauge. f25. p25.
Sizes of gas meters, {23, pl3.

of piping for gas engines, {23. pll.
Stiding'gear transmission system, {19, p2.
Slip of prrjpeller. f 19. p52.

of propeller. Apparent, §19, p52.

of screw propeller, §19, p46.
Slipped valve cams, 124. p24.
Siowing-down troubles with marine engines.

Causes of. (24, p5.
Small suction gas producer. Construction of,

120. p8.
Snap switches. {18, pM.
i>if,X on spark-plug porcelain, {24. p46.
Sfjark advance lever, §18. p38.

-c'/il connecti^^ms, §18, p25.

c'Al, Installation of battery and. f23, p29.

-c*jil trembler. §18. pp8. 28.

cr/Us. Care of. §18. p29.

cMs, Construction and operation of, §18,
p24.

gap, Auxiliary, §18, p35.

gap. Length of. §21, p8.

gap. Safety. §18. p27.

-plug di.srjrders, §24, p45.

plug. Leaky, §24, p47.

-plug pr^rce'ain. Broken, §24, p45.

-plug pr>rcelain. Soot on, §24, p46.

plugs. §18, p31.

•{/lug's requirements, §18, p34.

retardation in marine engines, Compressior
relief and. §22. p29.

timing. Testing. §21, plO.
Sjiarking, Timer contacts roughened by, §24,

pM.
Sfieed-change gear. Automobile, §19, pi.

indicator, §25, pi 7.
Spray carbureters, §17, pl6.

(arburetera. Advantage of, §17, pl8.
Sprinn, W<*ak or bnjken cxhaiist-valve, §24.
p24 .
WVak or broken inlet- valve, §24, p22.

Springs, Effe ct oi iinr qiuu tgnsioo at tnto

matic inlet-valve. §24, p23.
Spur-gear differential. §19, pL5.
Scrubber. Pilling the. §20. p22.
Stale gasoline. §24. ii36.
Start or of sudden stoppage of engine. Causes

of refusal to. §24. p2.
Starter for automobiles. Hand. §19, p24.
Starters for automobiles. Automatic. §19. p25.

Marine-engine. §19. p26.
Starting and governing de^-ices, §19, p24.
and running difficulties. Gas-engine. §24. pi.
and stopping automobile engines. §21. pl5.
bar for marine engines. Use of, §22. p27.
crank for marine mginrs. Use of, §22, p28.
devices. Care of. §23. p45.
Difficulties in. §23. p35.
Methods of. §23. p34.
Regulation of mixture in. §23. p35.
ninning. and stopping marine engines, §22.

p21.
stationary gas engines. §23. pp32. 50.
suction gas prodticer, §20. ppll. 25.
Stationary-engine carbureters, §17, pl9.
gas engine. Foundation of. §23. p4.
gas-engine management, Routine of. §£3,

p50.
gas engines and adjusting parts. Assem-

bUng. §23. p23.
gas engines. Examination of, §23. p2.
gas engines. Location of, §23, p4.
gas engines. Management and care of. §23,

p41.
gas engines. Piping system of. §^. plO.
gas engines. Selection of. §23. pi.
gas engines. Starting. §23. pp32. 50.
gas engines. Stopping. §23, p51.
gas engines. Water-cooling system for, §23.
pl9.
Sticking and broken piston rings, §24, pi 6.
Stoppage of engine. Causes of refusal to start

or of sudden. §24, p2.
Stopping automobile engines. Starting and.
§21, pl5.
marine engines. Starting, running, and,

§22, p21.
stationary gas engines, §23, p51.
suction gas producer. §20. p28.
Storage batteries, Care of. §18. pi 4.
batteries. Charging, §18. pl6.
batteries. Electrolyte for, §18. pi 4.
batteries, Laying up, §18, p21.
batteries. Renewing, §18, p23.
batteries, Secondar>' or. §18, pl3.
lotteries. Testing. §18, p20.
batteries. Use <tf alti'rnaling current in
char^nng. §>8. pll.

INDEX

XIX

Storai^c — (Continued)

batteries. Wiring ooimectiona for chaxging,
{18, pl7.
Suction and pressure gas producers. Compari-
son of, {20, p6.

gas producer. Qeaning pipe connections to,
{20. p29.

gas prodxioet. Construction of large, {20,
pll.

gas producer. Construction of small, {20, p8.

gas producer. Firing, {20. p27.

gas producer. Restarting, {20, p29.

gas producer. Starting. {20, ppll, 25.

gas producer, Stopping. {20. p28.

gas producers, {20. p6.

gas producers, Operation of. {20, p26.
Supporting engines on floor. {23. p8.
Sitrface and Altering carbureters. Objections
to. {17. pl7.

carbtueters, {17, pl5.

of propeller blades. Crowning, {19, p52.

of propeller blades. Driving, {19, p52.
Switch, Automobile battery, {18, p62.

High-tension, {18, p64.
Switches. Knife. {18, p60.

Snap. {18. p64.
Synchronism, {18, p48.

Tachometer, {25. pl8.
Tank. Cooling-water. {25. pl6

Gasoline. {22. pl6.

system of cooling, {23. pl9.
Tanks, Gasoline filling pipes and vents to

{22, pl8.
Tell-tale water circulation. {19. p42.
Temperature of cooling water. {23. pl9.

readings, {25. p26.
Templet, Engine-fotmdation, {23, p4.
Tension of automatic inlet-valve springs.

Effect of unequal, {24, p23.
Test, Log of gas-engine, {25, p20.

Method of making gas-engine. {25, pl9.

Report of gas-engine, {25, p22.
Testing carbureter, {21, p2.

batteries. {21, p9, {24, p45.

electrical connections, {23, p31.

Object of gas-engine. {25, pi.

producer for leaks, {20, p24.

spark timing, {21. plO.

storage batteries, {18. p20.
Tests. Shop. {25, p46.
Thermal efficiency, {25. p48.
Throttle, Carbiuneters with air inlet controlled

by. {17. p39.
Timber. Engine-foundation, {23. p8.
Time of ignition, {17. p2.

Tinnier contacts roughened by sparking, {24,
p53.

troubles, {24, p53.

wabbling. {24, p53.
Timers or primary commutators, {18. p37.
Timing, Incorrect, {24, p54.

Testing spark, {21, plO.

the ignition, {23, p40.

valves of automobile engines. {21, pl7.
Tools and repair parts, {22, p37.
Transmission system. Individual-clutch. {19,
p7.

system. Planetary, {19, plO.

system, Sliding-gear, {19. p2.
Trembler, Spark-coil, {18, pp8, 28
Troubles, Battery. {24. p44.

Cylinder-packing, {24, pl8.

Fuel, {24, p36.

'Lubrication, {24, p25.

Make-and-break igniter, {24, p47.

Miscellaneous, {24, p54.

Timer, {24, p53.

Water-cooling system, {24, p27.

Wiring, {24, p50.

with marine engines. Causes of dowin^
down, {24, p5.
True pitch. {19, p47.

U gauge, {25, p25.
Underwater exhaust. {19. p33.
Uniform pitch of screw propeller, {19, i>47.
Universal couplings, {19. pl9.
joint. {19. pl9.

Valve cams. Slipped, {24, p24.

Excessive lift of automatic inlet, {24, p23.

gear shaft. Assembling, {23, p26.

keys. Replacing exhaust, §21. p20.

Leaky carbureter float. {24, p34.

Mixing. {17. pl3.

spring, Weak or broken exhaust-. {24. |)21,

spring. Weak or broken inlet-. §24, p22.

springs. Effect of une(]ual tension of autj-
matic inlet , {24, p23.

stem or key. Broken exhaust , {24, p24.

stem or key. Broken inlet , §24, p24.
Valves and igniter. Examination of. {23. p33

Care of poppet, §23. p42.

Inspection of inlet. §21, p5.

Leaky inlet and exhaust, {24, p20.

of automobile engines. Timing, {21, pl7.

Regrinding, §24, p64.

Regrinding leaky, §24, p21.
Vaporizers, §17, ppl6, 29.

Disadvantages of, {17. p32.

INDEX

Vents to tanks, tiasoline filling pipes and, (22,

pl8.
Vibration, Prevention of engine, §23, p7.
Vibrator out of adjustment. Coil, $24, p49.

Wabbling timer. §24. p53.

Waste in gasoline pipe. Dirt or. $24. p33.

Water-circulating pumps. Types of, $19, p39.

-circulation pressure gauge, $19, p42.

-circulation tell-tale, §19, p42.

-cooling radiators, Types of, §19, p37.

-cooling system for stationary gas engines,
§23, pl9.

-cooling system. Inspection of, §21, pll.

-cooling system troubles, §24, p27.

in engine cylinder, §24, p66.

in exhaust pipe or muffler, §24, p65.

in gasoline, §24, p36.

gauge, §2o, p25.

-jacket. Deposits in, §23, p21.

-jacket. Repairing cracked. §24, p60.

I^ck of cooling, §24, p27.

Obstructed circulation of cooling. §24, p27.

Water — (Continued)

piping for marine engines. §22. pi 2.

-spray attachment. Carbureter with, §17.
p20.

supply. Cooling by steady. §23, p21.

tanks. Cooling, §25, pl7.

Temperature of cooUng. §23, pl9.
Weak battery, §24, p44.

explosions. Causes of, §24. p4.

mixture or charge, §24, p32.

or broken exhaust- valve spring;. §24. p24.

or broken inlet-valve spring, §24. p22.
Wet muffler, §19, p44.
Wire cable. Ignition, §18, p69.
Wiring cable. Broken secondary. §24. p51.

cable. Grounded secondary, §24. p51.
Wiring circuit, Break in primary, §24. p50.

connections for charging storage batteries.
§18. pl7.

Jump-spark. §18, p68.

Makc-and-break, §18. p65.

Short-circuit or ground in primary, §24,
p51.

troubles. §24. p50.

CARBURETERS

GASEOUS MIXTURES FOR GAS ENGHNTES

PROPORTIONS OP MIXTURES

EXPLOSION OF GASES

1. An explosion is an extremely rapid combustion
accompanied by the formation of gases and increased pres-
sure. A mixture of two or more suj^stances whose chemical
combination will cause an explosion is called an explosive or
an explosive mixture. There are also many chemical
compounds that will decompose into gases and vapors, the
decomposition producing an explosion. These are also
termed explosives. When the substance exploding is con-
fined in an unyielding receptacle, there is little or no noise;
but when the rise of pressure is transmitted to the surround-
ing air, as when the explosive is wholly or partially uncon-
finedy the explosion is accompanied by a rapid expansion and
usually by a. loud noise, or report. If the entire mass of the
mixture explodes instantly, it is said to detonate, and the
explosion is called a detonation. All detonating compounds
can be exploded by percussion, that is, by a blow or jar.
The best known example of the ordinary explosive is gun-
powder. Nitroglycerin and the substances derived from it,
dynamite and giant powder, are examples of detonating
compounds.

Cffyrif^kitdhy International Textbook Company. Entered at Stationers' Hall^ London,

117

2 CARBURETERS § K

When a combustible gas or vapor and air are mixed in
proper proportions and ignited, the combination of the gas
with the oxygen of the air is so rapid as to produce an explo-
sion. The sudden rise of pressure produced is made avail-
able for driving a gas engine.

2. Gases available for engine purposes vary so much in
their behavior when ignited in the gas-engine cylinder that a
knowledge of their performance is of great value to the
operator. Certain effects are produced when an explo-
sive mixture is confined in a closed vessel without the oppor-
tunity of expansion such as it has in the gas engine. These
effects relate to inflammation of the gas, duration of maxi-
mum pressure, and rate of fall of pressure. The relation of
these to the proportion of gas and air in the cylinder of a
gas engine is ver)^ important.

3. Igrnitlon. — The operation of setting fire to the gase-
ous mixture in the engine cylinder by means of a device called
an Igniter is called i^uriiitioii. The moment ignition begins
is called the time of igrnitiou. The quantity of the mixture
of gas and air taken into the cylinder at one time is called
the cliarpro, and when all of it is ig-nited, it is said to be
wliolly iullanied. The time elapsing between the time of
ignition and the moment when the gas is wholly inflamed is*
known as the diinitiou of inHniuniation or duration of
the explosion. The velocity with which the flame is gen-
erated in the charge is called the i-ate of flame propagra-
tiou.

•1:. Pivssiire CUauflres. — WTien the burning mixture has
reached its maximum pressure, a short time may elapse before
the pressure bc\:rins to full to that of the atmosphere. This
time is the duration of lunxlniuui pressure. The time
elapsing between the moment when the pressure commences
its fall from the maximum pressure and the moment when the
pressure reaches that of the atmosphere is the duration of
fhll of pressure. The velocity with wb.icii this fall of pres-
sure takes place is the i-aito of fall of pi*essure.

\17

CARBURETERS

5. Apparatus for Moasurlug Pressure Cliaiiires. — An

apparatus for measuring the changes of pressure in explosive
mixtures when ignited is shown in Fig. 1. It consists of the
explosion chamber a, similar to a gas-engine cylinder. The
interior of thechamberis connected by means of the passage ^
to the cylinder c of an indicator. The pressure in a, acting
on the piston rf of the indicator, compresses the spring e and

moves a pencil/ bearing against the dram g. The dram is
rotated by means of the clockwork shown. Motion is given
to the clockwork by the weight A, and the speed of the
dram ia controlled by the fan governor ('. The clockwork
rotates the drum at a constant speed, so that vertical lines
drawn on the surface of the drum at equal distances apart
win divide it horizontally into equal spaces indicating equal
intervalfl of time.

CARBURETERS

I— I

\ iv

V '

\ — s

r ^-^ — X — ^
V' X ^ I.

» 1 t 5 S' S

§17

CARBURETERS

6. The method of using this apparatus is to fill the
chamber a with a mixture of gas and air in known propor-
tions, and to ignite the mixture by means of an electric spark.
The drum having previously been provided with a removable
card and set in motion, the pressure generated by the explo-
sion compresses the indicator spring, raising the pencil,
which draws a line on the card. If the caj-d were now
removed and laid out flat, the diagram would be similar to
one of those shown in Fig. 2, which is a collection of dia-
grams, made with different proportions of illuminating
gas and air, all the gas used being of the same kind. The
vertical distances represent pressures in pounds per square
inch above atmosphere, and the horizontal distances repre-
sent parts of a second. The explosion chamber used in
these experiments was 7 inches in diameter by 8^ inches
high, or a trifle less than -^ of a cubic foot in volume.

7. Pressure Dlagrrams. — There are nine diagrams in
Fig. 2, each one showing the various pressures, during dif-
ferent parts of 1 second, for the explosion and other per-
formances of the different mixtures. Each diagram is indi-
cated throughout l)y a line of different construction than the
others, and is marked by a letter of the alphabet. The mix-
tures corresponding to each diagram are as follows:

Diagram

a
14

b
13

c
12

d
1 1

e
9

•

Volumes of Air to i Volume of Ga s

All diagrams begin at the lower left-hand comer, this
being the point indicating the time of ignition. From this
point, the pressure rises more or less rapidly to the point of
maximum pressure, remains there for a short time, and then
falls slowly as the cylinder walls absorb the heat generated
by combustion.

8. The mixture a reaches its maximum pressure of 40
pounds per square inch in .39 second after the time of ignition,
when the pressure remains at a maximum for .08 second, and

6 CARBURETERS § 17

then falls gradually to atmospheric pressure. At the expira-
tion of 1 second, the pressure within the explosion chamber is
19.5 pounds per square inch.

The mixture c reaches its maximum pressure of 60 pounds
per square inch in .'24 second, the pressure remains at a maxi-
mum for .025 second, and at the end of 1 second it has fallen .
to 19 pounds per square inch.

The mixtures/", g^ and // give nearly the same maximum
pressures, namely, 87 pounds, 90 pounds, and 91 pounds,
respectively. The duration of the explosion is .065 second
for/, .045 second for gy and .055 second for A, The wavy
condition of the summits of the lines is due to the vibration
of the indicator spring. All three of these diagrams slope
do^vnwards immediately after the maximum pressure is
reached. The fall of pressure is very slow at first, and the
rapid drop does not begin for several hundredths of a second.
For practical purposes, the maximum pressures may be said
to last about .04 second for g and //, and .02 second fory.
Diagrams^ and // after they cross the .2-second line continue
practically as one line until they cross the 1-second line at a
point indicating a pressure of 15 pounds per square inch.
Diagram/ crosses this line at the 16-pound mark, or just 1
pound above the point crossed by g and //. Diagram i shows
the peculiar behavior of a mixture containing one part of
gas to four parts of air. There is a gradual rise of pres-
sure for .08 second to 60 pounds per square inch, and from
this point the pressure increases by a series of jumps until it
reaches 80 pounds per square inch, .16 second after the time
of ignition. This ** jumping" is an effect invariably pro-
duced when the amount of air in the mixture is considerably
less than that required for the complete combustion of the gas.

It should be noted that in all these experiments the gases
arc at atmospheric pressure before ignition. If they were
compressed to a higher pressure before ignition, the rate of
flame propagation would be much more rapid.

9. Rate of Fall of Pressure. — The rate of fall of pres-
sure is shown by the diagrams to be very nearly the same for

§ 17 CARBURETERS 7

all mixtures. This can be realized most readily by noting
that all the diagrams are nearly parallel after the lapse of .5
second. The rate of fall varies from point to point, the pres-
sure falling more slowly toward the latter part of the dia-
gram. If the rate of f ^11 were uniform, this portion of the
diagram would appear as a straight line. Suppose, for exam-
ple, that the fall of pressure of diagram h was uniform after
a lapse of .4 second. Diagram h crosses the .4 line at a
pressure of 35 pounds, and the 1-second line at a pressure of
15 pounds; the fall of pressure for .6 second would then be
35 — 15 = 20 pounds, or 20-4- 60 = -J^ pound for each .01
second. Then, at the .5 line the pressure should be 35 — ^
(50 - 40) = 35 - 3| = 31| pounds.

In the same manner, it is found that the pressure at the
.6-second, .7-second, .8-second, and . 9-second lines should be
28J pounds, 25 pounds, 21f pounds, and 18^ pounds, respect-
ively. If a straight line is drawn through the points where
the .4-second line and the 35- pound line cross, and the 1-sec-
ond line and the 15-pound line cross, it will be found that
the line passes through the five points just mentioned, but
that the line of the diagram lies below the straight line. A
number of short straight lines can be drawn that will coincide
with the diagram. One of these short straight lines will
show the rate at which the pressure is falling at that i)art of
the curve, by continuing it until the amount of its slope can
be easily determined. A better way is to draw a straight
line just touching the curve at the point where the rate of fall
is to be determined. A line that just touches a curve and
does not pass through it is a tangent.

If it is desired to find the rate of fall at the point .45,
draw a tangent xy to curve at this point, and find that it
crosses the 0-second line at a point indicating a pressure of
57 pounds per square inch, and the 1-second line at the point
of pressure; hence the rate of fall at point .45 is 57 —
= 57 pounds per second. After diagram e passes the . 8 line
it will be seen to be practically a straight line ; and if it is con-
tinued backwards as a straight line, it will cross the 0-second
line at a point indicating about 32 pounds pressure. The

CARBURETERS

rate of fall is then 32 — 16 = 17 pounds per second. If this
rate is the same until the pressure falls to pounds, the
pressure will be equal to zero in 15-^17 = .883 second after
passing the 1-second line, or in 1 + .882 = 1.882 seconds
after the time of ignition.

In the same manner, the rates of fall and the time of
reaching zero pressure for any diagram of this nature may
be found.

10. Proportion of Gas and Air. — The best proportion
of gas and air to use for any gas, in an engine having no com-
pression, is not usually that which has the greatest explosive

TABLE I

PBOi-oirrioNs of mixtures and rksultino

i
ji

£
11

Hi
1

iiii

•^

600

46s

S3"

»J

t't

5'-S

731

560

640

780

S46

663

732

5=8

630

780

440

6to

«7

696

376

536

630

364

497

540

300

4»3

400

230

S^$

power. The best proportion is tliat which gives the highest
pressure for the quantity of gas used. For the purpose of
illustration, consider the distance between the en^ of the cyl-

§ 17 CARBURETERS • 9

inder and the end of the piston to be exactly 1 inch; then, for
each cubic inch contained in this space, there will be 1 square
'inch on the surface of the piston. The mixture that will
give the highest pressure for the same quantity of gas can
be calculated as follows: For instance, take the mixture con-
taining one volume of gas to five volumes of air. In 'Table
I, in which the results of the foregoing experiments are tabu-
lated, the maximum pressure for this mixture is given as 91
pounds per square inch. Since there are five volumes of air
and one volume of gas, for each cubic inch of gas there will be
six volumes of the mixture and to each cubic inch of gas, in
a layer 1 inch deep, there will be 6 square inches of the mix-
ture. Hence the pressure of 91 pounds per square inch is
exerted on 6 square inches, and the total pressure exerted by
each cubic inch of gas is 91 x 6 = 646 pounds.

The mixtures giving the highest pressure for 1 cubic inch
of gas are seen to be those having one volume of gas to twelve
of air, and one volume of gas to nine of air.

11. The mixture giving the best mean pressure for the
first .2 second is that giving 663 pounds to each cubic inch of
gas, or the mixture containing one volume of gas to twelve
volumes of air. If the power stroke could be considered as
taking place without increasing the volume of the space
occupied by the gaseous mixture, the pressure remaining at
the end of .2 second after the maximum pressufe has been
reached would be that given in column 7, and the mean or
average pressure at the end of .2 second after explosion
would be that given in column 8. Column 8 gives a means
of comparison of the power to be obtained in using the
mixtures indicated in column 1. Thus, the mixture having
one volume of gas to thirteen of air is more than twice as
powerful as that having one volume of gas to four volumes of
air, or in the ratio of 640 to 315, considering the power available
during the first .2 second after explosion. Of course, there
is no such thing as an engine running without increasing
the volume of the cylinder contents, but this assumption is
made in order to give a method of comparing the various

10 CARBURETERS §17

mixtures. The gas in each case must also be considered as
being so exploded as to have the time of maximum pressure
always at the beginning of the stroke.

1J3. Ilato of Flame Propagration. — The velocity or
]*iite of flaiuo propas:atlo]i is shown approximately in
I^'ig. 2 by the time elapsing between the time of ignition
and the maximum pressure. The rate of flame propagation
is approximately the velocity with which the pressure rises
after ignition. There have, however, been a number of
iiuicixjiidcnt experiments made with apparatus designed
expressly for the purpose. In this apparatus, the mixture
was confined in a tube from which the gas escaped at a
velocity that could easily be measured. The escaping gas
was then ignited, and the pressure gradually reduced nntil
I ho llame rushed back into the tube. The velocity of the
escaping gas was then just equal to the velocity of flame
pro^Kigalion in the mixture. This property of explosive
mixtuivs bocomcs less and less important as the pressure in
I ho >;as engine, Ix^fore ignition, increases, because the
higher the pivssure at the time of ignition the more rapid is
the rate oi tlame propagation.

<;.VS AND AIR MIXING

tH. Mixing C'hainlH^r. — The usual way of creating a
v.\MulnistiMo mixture of gas and air for use in a gas engine
is lo mtiXKhivx* the >ias inio a mixing chamber through which
I ho air is drawn inimodiatolv l>cfore it enters the cvlinder.
T*u* \:as ontoi^ the mixing chamber through a small poppet
valvo that is o^xMiod moohaTiically by a cam or similar
v-oxivO. .it I ho prv^^xM- tinu\ the an\i of the opening of the
>:,is \,v*\o N^i*.\v:' *.n piVjVMnivMi to the oiiantiiy of gas to be
sv.'.^:^'.'.ovl. r**.o nv.vinv; ohan^. Ix^r :s usually a part of the ga*-
ovc''^\ -ii'-vl *.^ .;:mo'h\; to t>.o oy!*v.v'.or as shown in Fig. 3.
y'*o ;; ;s 'v.^sNO^ :*v.\^v.v:-'i t>.o v.i'vo .: i:::o the mixing cham —
! v \ NX ' V * o .. r o • ^ : o :^ ,; : . . A t . :* i s shown the inlet valves
tx- :V.x* ox *v.v.x^v , ; ,;v.v: .;: < tV.o oxh,i::st \-aIve, The inle1C=-
x,\'\x ■ '.N ,; -N^^^'v*. \.;'\x\ V :wv\: Vv the oressure in th<

§17

CARBURETERS

mixing chamber when the pressure in the cylinder is reduced
by movement of the piston g on the suction stroke. The
exhaust valve /is opened mechanically through a cam and rod
rotating on the lever h. The gas valve a is also opened

Fig. 8

mechanically and closed by a spring, thus admitting a more
definite quantity of gas to the mixing chamber than a pop-
pet valve controlled only by a spring.

14. Begrulatln^ Flo^v of Gas. — It is necessary to
operate the gas valve a mechanically, for the reason
that the gas is under a certain degree of pressure, and if
the valve were opened by suction the exact amount of gas
going through would be somewhat uncertain. On the other
hand, the fact that the gas pressure is likely to fluctuate
renders it necessary to control the flow of gas to the gas
valve by a regulating valve that may be adjusted by hand.
This regulating valve is shown at a^ Fig. 4. It is provided
with an index and notches showing exactly how far it is
opened. When an engine is run on illuminating gas, it is
generally necessary to reduce the opening of the regulating
valve slightly at certain hours and increase it a little at
others, owing to fluctuation in the pressure of the gas in the

CARBURETERS

street mains. The gas as it conies from the main and sup-
ply pipe passes first through the meter 6, then through the
shut-off valve c, gas bag </, and the regulating valve a.

The gas bag, which is simply a strong rubber bag with
connecting tubes at both ends, is employed with all gas
engines using gas under pressure, to equalize the flow of

Fic. *

the gas. Between suction strokes this bag expands owin s
to the pressure of she jras. and when the suction strt>lK.<
iw-.'.rs the gas is taken o/,iiokly into the engine, partia-ll"
co'.lat^ing '.ho t\»ir, .inil conseniiently reducing the press**-"^*
\v;;h:n ii :o alx>iit th.it o: il-.e atmosphere. By the use ^■
this ce\-ice. the gys pressure at the inlet valve is k^^'M

§ 17 CARBURETERS 13

approximately constant between the beginning ana end of
the suction stroke, without the use of specially large piping
to carry the gas, as would otherwise be required.

15. The fact that the gas is underpressure, while the
air to be mixed with the gas is not, also has an influence on
the operation of the gas engine. If the engine runs very
slowly, the gas will enter the mixing chamber continuously
under its own pressure while the gas valve is open, regard-
less of the speed of the engine, while the air is drawn
through only in response to the suction of the piston. Con-
sequently, a larger proportion of gas will be taken in at
slow than at high speeds of the engine. In order to pre-
vent this and maintain an equal mixture at all speeds, the
gas-regulating valve must be adjusted by hand to suit
changes of speed. As engines of this sort are mostly used
in stationary work and run at a constant speed, this feature
is not very important, except when the engine is started,
at which time it may be troublesome, since a mixture of gas
and air in which the proportion of gas is too great will not
ignite. The operator must learn by experience the exact
position at which the gas-regulating valve should be set,
when the engine is turned over slowly, to produce the right
mixture for the first explosion. Most of the trouble of
inexperienced men in starting gas engines arises from their
lack of care and judgment in managing the regulating valve.

16« Mixing: Valve. — Another mixing device used in
connection with a mechanically opened inlet valve for regu-
lating the proportions of gas and air consists of a suction
valve arranged to close simultaneously an air inlet and a
gas inlet. It opens of course more or less according to the
intensity of the suction, and it is made as light as possible
so as not to require any greater amount of suction than is
necessary to open it. This kind of mixing valve, as it is
called, is used only when the engine is regulated by means of
a governor, which controls a throttle valve located between
the mixing valve and the mechanically opened inlet valve.

CARBURETERS

An iirrans^cment of this sort is shown in Pig. 5, in which a
iH the cumbuHtion chamber; b, the exhaust valve; c, the
.nuchiiiiiciilly opened inlet valve; li, the throttle valve; e,
the air intake; /, the gas intake; g, the suction-lifted mix-
inji viilve that opens both the air and the gas passages at
Uio Biinic time; and h, the water-jacket. In this device.

^o jTovomor riitates tho throttle valve d as the speed rises;
i:i w he;i the S]X'<.\1 l»ei.\>mes excessive the passage is closed
"ov.j;':: :o r(.\:»;vX" the charge taken into the cylinder to the
iV-.-ire.; .in'.i>-,:nt.

jx-:i-.;cs :hcsL> simple derices for producing a UQiform
::x:-,:tv .:' si.is a::^; air, tlwTV is a large number of special
:;v;-;s :.7 ,<\v.o;.i] nie^s ar.i,i s'.xviol tvpes of engines, the
■•.■#; i~-.-.vr;.ir.: o: wV.ioh w." Iv ivnsidered later.

CATWt-RW-lTlOX

■ :-.■.;•'". -.T .V cv.s t:~jr-"-e is a gaseous mixtnre
. i-v.rVr., .\-.^ Air, 1: is prwdaced by mixing
-:" >,v»=r.v,ir'S.-ia wiih air, Tlie hydrocarbon ia

§ 17 CARBURETERS 15

a substance containing hydrogen 4ind carbon in such a form
as to bum readily with the proper mixture of air. Gas
engines located so that they can be supplied with natural or
artificfal gas will usually receive such fuel; but when not so
situated, they will be supplied with fuel in the form of car-
burized air. The most convenient form of hydrocarbon for
this purpose is the liquid form, such as gasoline, alcohol,
and kerosene. These liquids can be readily transported in
tanks and they are obtained directly as a product of nature,
needing only to be distilled, refined, or purified.

The evaporation or vaporization of these liquids and the
mixing of the vapor with air is called carburizatlon.

TYPES OF CARBURETERS

PRINCIPLES OF THE CARBURETER

IS. Classlflcatlon of Carbureters. — A carbureter is

an appliance for vaporizing liquid hydrocarbons by pass-
ing air either over the surface of or through the mass of the
liquid or by atomizing the liquid and mixing it with air.
The air thus becomes saturated with the vapors of the
hydrocarbon. This mixture invariably contains too large a
proportion of vapor for an explosive mixture; therefore,
before the mixture can be exploded in the engine cylinder it
requires the further addition of air.

Carbureters may be divided into three classes, as follows :

1. Those which use a large surface of the hydrocarbon,
generally spread out in thin layers, and over which air is
compelled to pass. These, for the sake of convenience, will
be called surface carbureters.

2. Those in which the liquid fuel is placed in any con-
venient reservoir, usually of great depth, in proportion to
the horizontal dimensions, and the air is compelled to pass
through the body of the liquid. These may be called fll-
terixt^ carbureters.

3. Those which vaporize or atomize the hydrocarbon and

CARBURETERS

SI7

Inject it into a current of air. These may be calledspivr
carbureters, or vaporizers.

The first two tj-pes preceded the third in point of time,
but the spray carbureters are now used almost entirely.

10, Spray Carbureters. — A good example of a spray
carbureter or vaporizer is shown in Fig. 6. It is used in
tftinnectiou with stationary gasoline engines, and gives very
satisfactorj- results. The fuel is drawn to the engine

#;;j,-r..-c .e :2ie e agin e. The
■,>&-:r5t ,-£ ijse icci=g f daring
•^. i.-^^ trtf irr=:^ closes the

■ V, -■ .- «•> ,'t^r At tcp of the

■S:-. . Tae ffMBfjar is fed

§17 CARBURETERS 17

to the vaporizer from a tank placed above the level of the
engine ; flows first to a reservoir that regulates the flow
to the vaporizer by the head due to a constant level main-
tained by an overflow. From the reservoir, the gasoline
flows to the compartment /, from which it is admitted to
the chamber g by the needle valve h. The distance the
needle valve is opened is indicated on the gi*aduated circle i
by the stationary pointer/. From the chamber g^ the gaso-
line is admitted to the mixing chamber e by opening the
valve k^ which is rigidly attached to the inlet valve b. The
mixing chamber entirely surrounds the chamber g^ so that,
when the suction of the engine lifts the valve b and thus
opens the valve k^ the gasoline rises through the opening
and spreads over a considerable surface. The heated air in
the mixing chamber vaporizes the gasoline, and the carbur-
ized air rushes through the valve b and the passage a to the
engine.

When it is desired to use gas with this device, the gas-
supply pipe is connected to the carbureter at /, so that the
gas and air mix in the chamber e and the mixture is
drawn into the engine through the passage a as the suction
lifts the valve b^ precisely as with gasoline. In either case,
the charge passes from the inlet valve in the direction of
the arrows past the throttle, or butterfly, valve ;;/, which is
operated by the short crank // outside the pipe. A rod from
the governor is attached to the crank //, so that, as the
speed of the engine increases, the valve is gradually closed ;
and, as the speed decreases, the valve is opened, thus regu-
lating the fuel supply.

20« Objections to Surface and Filtering: Carbu-
reters. — In the early days of the gasoline engine, the fuel
was vaporized simply by having the air drawn over it, or in
some cases drawn through it in the form of bubbles by the
suction of the piston. Sometimes, to give an increased sur-
face for evaporation, a spiral coil of flannel or other suitable
material, as wicking, was arranged so that it would stand
partly out of the gasoline, and the air would be drawn over

168—3

.^ _kl A. -■■^* .

18 CARBURETERS § 17

the surface of the gasoline and the wicking. All devices of
this sort have gone out of general use, on account of several
important objections. Plain surface evaporation requires a
very large surface, in order to evaporate the gasoline fast
enough to supply an engine large enough for average
demands for power. Again, gasoline is not a homogeneous
compound ; it is a mixture of light and heavy products of
petroleum. When it is evaporated from the surface, the
lighter constituents are evaporated first, and hence in time
the carbureter contains only the denser portion or stale
gasolinCy as it is called, which will not evaporate with suf-
ficient rapidity to supply the air with the amount of hydro-
carbon necessary for explosion. Another objection to car-
bureters of this sort is that the rate of evaporation of
gasoline will depend very largely on its temperature and it
is difficult to supply the heat necessary to maintain the
required temperature. The gasoline is cooled by its own
evaporation, and the heat to make up for this must be sup-
plied in some way, usually by warming the air before it
goes into the carbureter by drawing it through a jacket
around the exhaust pipe of tlie engine. Sometimes the
gasoline is warmed by means of a jacket around the car-
bureter, through which is circulated water from the jacket
of the engine. If the engine speed is at all variable, the
supply of heat varies. It follows that the gasoline, or the
air that evaporates it, receives more heat at some times than
at others, and the richness of the mixture fluctuates accord-
ingly.

tj 1 , Advautaii^e of Spray Carbureters. — For the rea-
s<^ns just stated, the surface and the filtering carbureters
for internal-combustion engines have been abandoned, aix<l
their place taken by a large variety of forms of sprayii::^^
devices. In these, the gasoline is given to the air in
form of a jet, or spray, that is drawn from the supply
the air current. When the air is sufficiently warm, tfais
spray is evaporated and a fairly constant mixture of air anc?
ga.soline vapor is thus obtained.

1_. k :

8 1?

CARBURETERS

The spray carbureter takes up only a small amount of
space, and hence can be located to better advantage. For
automobiles and motor boats, this is very important, as the
space available is small and access to all parts is as neces-
sary as in stationary engines.

9TATIONART-ENQINE CABBDBKTBBS

33, Vaporiser. — In stationary engines, the mixing
device, or carbureter, is frequently constructed as a part of
the engine, and is then usually known by some other name.

oh as vaporizer, or atomizer. A vaporizer for a horizontal

tionary engine is shown in Fig. 7. The air enters through

passage shown at a, and the gasoline through the pipe b,

nected to a gasoline tank located above the engine.

s inlet valve c is opened automatically on the suction

Ite of the piston d. The water-jacket that surrounds

cylinder is shown at e. The gasoline entering at b flows

the adjustable needle valve/" to the cone-shaped valve

'Mch is normally held to its seat by a spring, but is

20 CARBURETERS § 17

lifted or pushed forwards during the suction stroke by the
tappet //. So long as the valve g is seated, the gasoline can-
not pass it, but when it is open the gasoline flows from the
small hole drilled in the valve seat, and, passing around
the conical head of the valve, issues from the spray nozzle i.
Here it is taken up by the air stream, which passes through
the constricted passage around the spray nozzle with consid-
erable velocity, the vaporization being aided by the conduc-
tion of heat from the engine cylinder through the surround-
ing metal. The function of the needle valve f is to
regulate the rapidity with which the gasoline is drawn in
by the air. The heady of this valve is graduated, to indi-
cate exactly the valve opening.

*■ ■ • . • •

23. Ix>catlon of Gasoline Supply. — ^Usually, it is not

convenient to locate the gasoline tank above the engine, since it
ought properly to be buried in the ground to keep it as cool
as possible and protected from the air. When that is done,
the necessary head may be obtained by attaching to the
engine a small pump by which the gasoline is lifted from
the tank and carried to an overflow cup located above the
mixing chamber. From this cup the gasoline not taken
into the engine flows into a return pipe having its inlet
located at the proper level in the cup, and passes back to
the tank.

24. Carbureter With Water-Spray Attadunent.

A sectional view of the carbureter and mixing chamber as
designed for the use of gasoline in engines using a water
spray for cooling the combustion chamber is shown in
Fig. S. The air supply is so regulated that a certain por-
tion enters through the passage n, while a sufficient amount
to vaporize the fuel is admitted through the opening b.
The tr.e! is supplied by a pump, operated from the engine,
to a sriiall tank r, in which a constant level is maintained by
t'-.e overr.ow */. From the resen-oir r, the fuel flows to a
sniall orir.ce, the opening of which is regulated by the
r.eei'.e vaIvc c which is provided with a stuffingbox for pack-
ing. The highest point of the noule/ through which the

§17

CARBURETERS

fuel is sprayed into the carbureter, is slightly above the
Icii-el of the gasoline in the reservoir c. The air-current,
passing the nozzle f with considerable velocity, creates a
suction at this point suflScient to draw a certain amount of
gasoline, in the form of a spray, into the carbureter. After
passing through several layers of fine-wire gauze at ^, the

air and atomized gasoline are admitted through the gasoline
valve h into the mixing chamber a, where they are mixed
witli sufficient air to form an explosive mixture. This mix-
ture then passes into the combustion chamber through the
main inlet valve i.

22 CARBURETERS §17

26« The opening of the gasoline valve h is con-
trolled by the governor, in order to proportion the fuel to
the demands for power. The blade j pivoted on the valve
nut k engages with an arm on the valve mechanism
whenever the speed is normal. Under light loads, the gov-
ernor moves the blade j out of the path of the arm ; hence
the valve h remains closed and the engine receives air only.

When working under heavy k)ad, the engine is liable to
heat up more than under light load. To avoid premature
ignition imder these conditions, provision is made to add a
small quantity of water to the mixture of air and gasoline,
which has the effect of cooling the combustion chamber.
This water supply is admitted to the mixing chamber
through the nozzle / regulated by the needle valve w. The
gasoline vapor passes through the wire-gauze screen g
before it meets the spray of water. The reservoir c is
divided by a partition into two chambers, one for gasoline
and one for water, the water entering through the supply
pipe, connected to the tank near the top, while the excess
water is carried off by the overflow pipe «, the amount avail-
able in the reservoir being regulated by the height of the
overflow pipe that projects into the reservoir.

/J 6. Carbureter With IIlt-or-Miss Governed Gaso-

line Inlet. — A form of carbureter in which the gasoline-
inlet valve is controlled by a hit-or-miss governing device is
shown in Fig. 9. The fuel enters the cup a through the
supply pipe fitting ^, containing an overflow- through which
the surplus gasoline delivered by the pump returns to the
storage tank. A float (not shown in the figure), guided in
the small hole c in the upix^r part of the cup, shuts off the
supply to the cup as soon as the gasoline reaches a certain
level. The fuel supply to the engine is shut off by the valve
d. The main inlet valve c is provided with the washer/, to
which is connected a sleeve, guided in the casing g and
sliding on the stem of the main inlet valve e. The governor
is connected to the fmger //, pivoted on the sleeve of the
washer /", and when the governor permits the finger to

gl7

CARBURETERS

engagfe the nut i, the valve e on opening carries with it the
washer /, which strikes the stem of the gasoline valve/ and
opens it. A small quantity of gasohne is thus allowed to
flow from the passage and space above the valve and to
enter the air passage k through the hole i. The velocity

of the air-current is such that the fuel, which enters the air
in a fine stream, is vaporized and with the air forms a
combustible mixture while entering the combustion chamber
through the valve e.

37. Carbureter Witt Hlt-or-Mlss Governed Air
Inlet. — Another arrangement for admitting and vaporizing

CARBURETERS

§"

the fuel for a stationary gasoline engine is shown in
detail in the vertical section. Fig. 10. This vaporizer does
not, however, form a part of the cylinder head, but is con-
nected some distance from it. The gasoline -valve casing a
is attached to the air-inlet casing d. Gasoline is pumped from
the storage tank through
the supply pipe £ into
the space in tl.e valve
casing a. A partition
d, dividing this space
into two compartments,
keeps the gasoline at a
constant level, slightly
below the top of the
nozzle pipe*", the excess
delivered by the pump
returning to the tank
through the overflow
pipe / A threaded
needle valve /■ regu-
lates the gasoline ad-
mitted to the valve cas-
ing a, while the dial
val\-e A serves to shut
off the supply when
stopping the engine.

The air enters the pas —
sage leading to the inlett=
valve i from the air pipey which taVes the air from the out
side. At the point where the nozzle -r is inserted, the area o -
the air passage is reduced so as to create a high velocity of th _
air-current at this point, resulting in a strong suction whic~ -=
drawsaquantity of gasoline from the casing a through a sma~ _
hole in the upper end of the nozzle r. The gasoline is thi^ — ;
atomized by the air-current, and the combustible mixture l.
.\ir and gasoline vapor passes upwards ioto the combostic^-
ohaniV^T t. through the val\-e i. It has been fotind that ■*
Igh velociiy at the point where the gasoline enters tB»^

f~■^ - "i

1 -

|.|

1 ■

- ^

§ 17 CARBURETERS 25

air-current, contributes largely to the efi&ciency of the gaso-
line spray.

3 8. Owing to the strong suction through the inlet valve
of the arrangement shown in Fig. 10, there is a possibility,
especially if the inlet- valve spring should become weakened,
that the inhaling action of the piston may cause the inlet
valve to chatter, or open to a slight extent, even when the
exhaust valve is open while no charges are needed to keep
up the speed of the engin9 under light load. This would,
of course, result in a waste of fuel, which Tyould be drawn
into the cylinder, and, forming too weak a mixture, would
be expelled through the exhaust pipe without being exploded.
To prevent this, the push rod that opens the exhaust valve
and is controlled by the governor has an arm or extension
connected by a horizontal rod to a lever m. When the gov-
ernor causes the exhaust valve to be kept open, the lever m
is moved in between the cylinder head and the washer on
the end of the inlet valve, thus positively locking this valve
and preventing it from being even slightly opened.

29. Kerosene Engrine Carbureter. — A sectional view
of t»ie carbureter of a kerosene engine is shown in Fig. 11, in
which the exhaust valve is shown at a and the inlet valve
at by both opening into a passage connected to the end of the
cylinder. The valve b admits the air required for combus-
tion ; it is automatic in its action, being opened by the par-
tial vacuum in the cylinder during the suction stroke and
closed by the tension of the spring c. The dashpot d at the
upper end of the valve stem is for the purpose of preventing
the valve from coming to its seat too suddenly.

The needle valve e that admits the kerosene to the com-
bustion chamber is operated by the lever y. The bushing^
surrounds the valve and fits into the bracket h that is bolted
to the cylinder. The nut i with the opening/ is screwed
Into the bushing^, and furnishes the seat for the needle
valve e. Between the needle valve and the bushing are
brass washers ky perforated with small holes, through which

26 CARBURETERS g IT

the oil, entering from a pipe not shown, is forced by com-
pressed air, which enters through the pipe /. Cooling water is
supplied to the space around the bushings, entering through
a pipe not shown, and passing out through the pipe m. The
joint around the needle valve is made tight by means oi

the ring «, the packing o and the gland p. The fuel is
injected into the combustion chamber at the end of the
compression stroke, when the air admitted during the sue
tion stroke has been compresseil to about 600 pounds per

Wiiiarc inch.

§ i: CARBURETERS 27

The fuel is injected into the highly compressed contents
of the cylinder by means of air compressed to about 700
pounds per square inch, the air being furnished by a sepa-
rate compressor driven by belt either from the engine or
from a convenient shaft. The temperature of the air in the
cylinder at the end of compression is about 1,000° F., which
is considerably above the temperature required to ignite the
mixture without the use of any special igniting apparatus.
The oil is finely atomized by being pressed through the
numerous small holes in the brass washers k^ thus entering
the combustion chamber through the nozzle in the form of
a very fine spray. Owing to the high temperature of the
compressed air in the cylinder when the fuel is injected, the
combustion is practically perfect, leaving no residue and
producing clean exhaust gases.

AUTOMOBILE AND MARIXE CARBURETERS

30. The conditions under which the carbureter on an
automobile must operate are more exacting than those found
in connection with any other gas engine service, for the rea-
son that an automobile motor runs at all speeds and under
greatly varying loads, and the carbureter is exposed to great
variations of temperatures and atmospheric conditions. It
naturally follows that the simple devices found succesvsf ul on
stationary engines are by no means reliable when applied to
automobiles, and even a successful marine carbureter may
fail to give the best results, when applied to an automobile,
although any carbureter found successful on an automobile
will be equally successful in a motor boat.

31. Requirements for an Automobile Carbureter.

A successfi\l automobile carbureter must fulfil the following
requirements:

1. It must give a practically uniform mixture, whether the
demand on it is light or heavy, within the range of the speed
actually attained by the motor. The mixture must be the
same when the motor is running slowly with the throttle

28 CARBURETERS § 17

wide open, as when going up a hill, or slowly with the throt-
tle nearly closed, as when coasting or traveling slowly
on the level, or when running at top speed with the throttle
wide open.

2. It must not freeze up in cold weather, through the con-
densation of moisture from the air and freezing in the mixing
chamber.

3. It must not be unduly sensitive to changes in the qual-
ity of the gasoline, and it must admit of easy adjustment
for such ordinary variations in density as are likely to be
encountered.

4. It must not be unduly sensitive to changes in the level
of the car, as when climbing or descending a hill, or when
turning off the road into the gutter.

5. It must vaporize the gasoline reasonably well when
starting in cold weather.

6. It must operate equally well whether the motor has one
or two cylinders giving intermittent suction, or a larger
number of cylinders giving practically a continuous suction.

7. The quality of the mixture delivered must not be
affected by the vibration of the car.

8. The carbureter must not be exposed more than necessary
to the entrance of dirt, and all parts to which dirt is likely to
find its way must be readily accessible for cleaning.

It is evident that with so many requirements there is
no carbureter made that fulfils all of them equally well.

32. Regrulation of Automobile Carbureters. — Prac-
tically all carbureters for automobile use are of the constant-
level type. The gasoline passes from the tank through a
needle valve to a constant-level chamber, in which the level
of the gasoline is controlled by a float that acts on the
needle valve, closing it when the level reaches the outlet of
the spray nozzle. In this way the rate of gasoline feed to
the spray nozzle is determined solely by the degree of
vacuum existing in the mixing chamber, and the velocity of
the air stream, irrespective of the amount of gasoline in the
tank. The combined influence of the vacuum in the mixing

§ 17 CARBURETERS 29

chamber and the velocity of the air stream is to make
the mixture richer when the motor is running fast and the
throttle is wide open than it is when the motor is run-
ning slowly with open throttle, or fast with the throttle
partly closed. In the first case there is considerable
vacuum and a high velocity of the air, while in either of
the other two cases there is less vacuum and a smaller veloc-
ity of the air. This is because the throttle is located
between the carbureter and the motor, and not at the car-
bureter intake, so that, whatever the vacuum may be
between the throttle and the motor, the vacuum in the car-
bureter itself is reduced by the throttle valve so that only
the amount of air required by the engine will be drawn in
at each stroke.

The vacuum between the throttle and the motor has no
effect on the amount of gasoline vaporized; this depends
only on the speed of the air that is drawn through the car-
bureter.

The rate at which the gasoline is drawn from the spray
nozzle is affected by both the vacuum and the air velocity
more than it would be by either separately, so that, when
neither is restricted, too much gasoline is evaporated. It is
desired to keep the flow of gasoline as nearly as possible
proportional to the velocity of the air, and in order to
accomplish this result the newest forms of automatic carbu-
reters restrict either the velocity of the air stream or the
vacuum in the carbureter, as the demands of the motor
increase.

33. Vaporizers. — In a larger number of marine
engines, and in all automobile engines, the carbureter, or
vaporizer, is a separate device; that is, it is not a part of
the cylinder head. A simple form of vaporizer is shown in
Fig. 12. The air in entering takes the course shown by the
arrow, lifting the trap valve or mixing valve a to a. greater
or less extent, according to the intensity of the suction.
The end of the valve has a leather pad that, when down,
closes the gasoline spray orifice ^, and when lifted, allows

CARBURETERS

j ll-

the gasoline to escape. The pressure that catises the gaso-
line to rise in b is due partly to gravity, owing to the Icca-
tion of the reservoir, and partly to the suction of the air
that picks up the gasoline and breaks it into spray as the
air-current passes the
orifice b-. The gasoline
comes from a tank or
overflow cup shove the
level of the mixing
valve, and its rate of
flow through the spray
orifice may be adjusted
by the threaded needle
valve c. The air regfu-
lating valve d may be
opened or closed by
hand. This valve ad-
mils air through the
ports c, e to dilute the mixture; and by its use, the mixture
may be regulated to the exact pro- _^_

portions required without disturbing
the needle valve. Regulation of
this sort may be required for a
change in the speed of the engine.

34. Another simple vaporizer is
shown in Fig. 13. The air enters at
a, and, as it passes upwards in the
constricted passage, it impinges ^^
sharply on the small flange b of the
needle valve c, thereby lifting the
valve to a greater or less extent,
depending on the velocity of the
air-ciirrent. In this way, the flow
of the gasoline is regulated roughly ^^°' '*

according to the velocity of the air. A stop d is provided
above the needle valve, to prevent it from lifting so hiff^
that it will not have time to close by its own weight at the

CARBURETERS

end of the stroki;. The connection to the gasoline supply is

made at c, and the gasoline rises to the needle valve by the
pressure due to the height of the gasoline tank.

35. The vaporiKcr shown in Fig. 14 is used to a consid-
erable extent in motor boats. Its operation depends on the

Tacuum produced by the suction ol the engine. The pres-
stire of the air that enters at a lifts the valve l> against the '
pressure o£ iJie spring c, when the engine is taking in a new
charge. The gasoline enters around the needle valve (/,
and is sprayed from the passage i- when the valve ^ is lifted off
its seat. The band wheel / of the needle valve is graduated,

8*^ CARBURETERS § 1

to indicate the opening. The pointer g can be moved
to any position and locked there by the locknut //. The
stop /can be adjusted so as to gfive the desired amount of
opening to the valve b. The baffle wally deflects the mix-
ture upwards and causes it to mix more thoroughly without
reducing the area of the passage k through which it passes
lo the engine. The baffle wall also serves to prevent any
liquid gasoline from flowing to the engine.

JiO. 1 )tsiul vniitii^es of Vaporizers. — Vaporizers like the
ones shown in Figs. 13 and 14 are much less common now
than in the past. They arc very wasteful of gasoline, and
ivquiix^ fre(|uent adjustment to make them supply the
pnqKM* nnxluR\ One of their most obvious disadvantages
is that the g^asoline will flow more rapidly to the needle
valve when the tank is full than when it is nearly empty, on
account K^i the ditYerence in pressure due to the height of the
s\ui\ux^ above the valve. The proportion of air to gasoline
is alsv> noi eniirv^ly constant when the engine speed changes,
or when the ens;ine is throttkxl. There is a tendency for
the mixtuiv lo be tov> rich at high engine speeds, since the
flow of gasoline is not vMily due to the pressure from the
elevation i^f the ta!\k, but is als«.> due to the partial vacuum
c\\itii\g in the mixiuii' ohanilx^r and to the velocity of the
air. Va et\ if no vaouum exist cvl in the mixing chamber and
;f the \:asv>line hav! r.v^ pressure at the needle valve, the gaso-
ir/.e Wv^v.'.vl s:r,* K^ crawn into ihe a:r bv the velocitv of the
\\ \\.\\ \\\\\s *v seen :ha: ther^ an^ four factors that

atKo: :V,o \^rv^\\>r::v^i\s ot ihe mixture; namely, the head of
:'\o ci^v^*v,H" *'.*. tV.e tar.k. t'u^ !::: of the needle valve, the
\,;o;\v*,\*, v.\ ;>e '.vix-v-c v>,a:v.:x^r, ar.vi the velocitv of the air.
WV.at ts ivaV.v vUn -.xv, -s :ha: or.'.y ihe last named of these
•x ; • tav;vv>i sv^uM K^ v^ix^rav.w: or, in other words, that
t*'o \v*xV't\ x^^ :>x^ v:a>x\ir,c v: sho"\; 'Se :n din?ct proportion
\o\vu\ V : :>.o ar.\ T>.:> :> r.vi Ait-dned in the type

« k % «

» X « N

N « , >'t*v^t-l\xH\ I'^irburxncrs. - 7.":e irne-oriilaritv in the

^ .V. ' -,^ '.vx ,,0 ;.^ \.r-,;: .•> : ; :>.c level of the gasoline

CARBURETERS

in the tank, is eliminated hy passing the gasoline from the
tank through an overflow cup attached to the carbureter, or
through a chamber in which the proper fuel level is main-
tained by a float; so that, when the gasoline rises above the
proper level, the float closes the inlet valve. This last
method is used almost entirely in automobiles, and also to
a large extent in motor boats.

A simple form of float-feed carbureter is shown in Fig. 15.
The gasoline enters the carbureter at a from the supply tank,
and passes through the valve d into the float chamber c.
The proper level for the gasoline in this chamber ia at or

very slightly below the top of the spray nozzle d, and
when this level is reached the float *•, which is hollow and
very light, closes the valve A. The air entering at / flows
with considerable velocity through the passage^, and, as it
does so, a jet of gasoline flows from the spray nozzle d.
This flow is caused partly by the velocity of the air-current
and partly by the vacuum induced by thfr piston. Owing
to the velocity of the air, this jet is immediately converted
into fine spray in the mixing chamber i, and then passes

CARBURETERS § 17

into vapor aljiiost immediately. In order to supply the heat
demanded by this extremely rapid evaporation, the inflow-
ing air is sometimes warmed by being drawn throngh an air
jacket around one of the exhaust pipes, or is taken from the
warm space between the cylinders below the water-jacket
In other cases, the air is not warmed before it enters the
carbureter, but the annular chamber i around the carbureter
is supplied with either exhaust gases or water from the
water-jacket of the engine,

38. Aiitomutlo Float-Feed Carbureter. — A modified
lorm of the carbureter shown in Fig. 15, known as an auto-
matic carbureter, is shown in Fig. 16. The gasoline

Fro. W

comes from the tank through the opening at a, and the
prinoiivil air stream enters at !>. The float c closes the
valve ./ when the lovel of the gasoline reaches the top of the
spray ui'.r.-lo c. When the engine is running very slowly,
thi- air ciuoring at /• is all that enters the engine, bot as the
tliri'ttto is ^llx>n^'^.l nioa- and more, the vacutun in the mix-
ing i-haniK-r is iiicrt'asi'd and the valve f is opened against

§ 17 CARBURETERS 35

the resistance of its spring. Air is then admitted in greater or
less quantity, depending on the amount that the valve / is
opened, which, in turn, dei)ends on the vacuum, or the
speed of the engine. This air does not pass the spray noz-
zle, but is mixed with the carbureted air in the mixing
chamber^. The effect of the valve f is thus partly to
reduce the vacuum that would otherwise exist ia the car-
bureter, thereby diminishing the amount of gasoline sucked
from the spray nozzle, and also to dilute the air actually
carbureted.

The two plugs h and / are provided for cleaning the carbu-
reter of any foreign matter, as dirt and watery that may be
carried in with the gasoline. As almost all such matter is
heavier than gasoline and tends to settle to the bottom, it is
only necessary to unscrew these plugs and cause a little
gasoline to flow through. The annular jacket/ is connected,
by pipes not shown, with either the exhaust pipe or the
water-jacket of the motor, and this serves the purpose of
supplying the heat required by the gasoline in the process of
evaporation, thus preventing condensation and freezing of the
moisture in the air.

To start the motor, the stem k is depressed, thus opening
the valve d and permitting the gasoline to escape freely
from the spray nozzle. In this way a sufficient quantity of
gasoline is allowed to gather in the intake pipe to produce,
simply by evaporation, the mixture necessary for starting.

39. Another type of automatic carbureter that has
proved very successful is shown in Fig. 17. The air
enters at a and the gasoline at b. The height of the
gasoline is controlled by the float c which, as it falls,
presses on the levers d^ d, and raises the weighted needle-
valve stem e. When the float rises, the needle valve is
closed by its own weight. As the gasoline comes from
the float chamber, it issues from a number of very small
slots f in the conical head of the spray plug g. This plug
is drilled upwards from the bottom, and then laterally, as
shown by the dotted lines, to admit the gasoline to the

CARBUKETERS

il7

Space beneath a conical cover or head h. The division
of the entering gasoline into a number of very small
jets (from 10 to 16) insures a much more rapid and effi-
cient mixing with the air than when the spray enters in a
single jet The air coming up from a strikes the head h.

which is pierced at the top with a number of small holes
through which the air passes on its way to the throttle
valve /. The cone h is attached to the stemy* to the other
end of which is connected a plunger i working against a
spring in an air dashpot. When the velocity of the air is

§ 17 CARBURETERS 37

small, practically all the air passes up around the spray plug,
and through the holes in the head //. When the suction
increases, however, the air strikes with so much force against
this head that it is lifted against the resistance of the spring,
and a portion of the air is diverted and passes around the
lower edge of the thimble, so that it has no effect on the
gasoline spray.

Although this arrangement does not increase the amount
of air drawn through the passage ^ , it gives the air an easier
passage when the head is lifted, a smaller proportion of the
air passes the gasoline plug, and the same result is therefore
produced. As the carbureted air is divided by the holes in //
through which it must pass, and the air that passes beneath
the head flows against the stream of carbureted air on all
sides, the two streams are very thoroughly mixed, which is
not always the case in carbureters with automatic air-inlet
valves. The ptupose of the air dashpot connected to the
head h is to check the pulsations of the latter when the
engine has only one or two cylinders. Although the head is
made as light as possible, it is found that owing to its inertia
it does not follow perfectly the variations of the air-current
when the suction is not steady. The effect of the dashpot,
however, is to cause it to lift to an extent determined by about
the average intensity of the suction, and to remain in prac-
tically that position from one impulse to the next. The
carbureter is primed by unscrewing the valve / a fraction of
a turn, permitting the gasoline to escape directly into the
intake pipe a. A spring ;;/ insures the closing of the valve
when released. The throttle valve i is elliptic in shape, as
indicated, in order to make it unnecessary to turn it to an
angle of 90° from the wide-open to the closed position. As
in the carbureter shown in Fig. 15, there is a jacket n con-
nected to the exhaust pipe and serving to supply the heat
taken up by the evaporation.

In another form of this carbureter, a stop-screw is provided
to limit the lift of the head, and a needle valve, adjustable
from the bottom, is provided to restrict the rate of flow of
the g^oline to the spray i)hii:^.

§ 17 CARBURETERS 39

40. Another automatic carbureter is shown in Fig. 18
(a) and (^), the two views being taken at right angles to
each other. The air enters through the slits a. Fig. 18 {a)j
in a shutter that can be rotated so as to close them, or give
them the amount of opening desired. The air passes through
the openings 6 in the standpipe c that is made small in order
to give the air considerable velocity as it passes upwards past
the spray nozzle. The carbureted mixture is then diluted
by air coming through the automatic valve e, and the final
mixture passes out through the throttle valve / into a
branched mixture pipe, which bends upwards and leads to
the cylinders. The gasoline enters at^, Fig. 18 (b), and the
float, as it rises, causes the small levers A, A to push
the needle-valve stem i downwards, thus stopping the flow
of gasoline. By means of the connections y and ^, warm
water from the water-jacket of the engine is circulated
through the jacket /, Fig. 18 (^), of the carbureter.

The carbureter is primed for starting by lifting the needle
valve /, Fig. 18 {b). There is no needle valve acting on the
spray nozzle, but the richness of the mixture is regulated by
adjusting the openings of the slits a. Fig. 18 (a). This is
done by means of a shutter surrounding the pipe in which
the slits are cut. . This shutter has openings cut in it corre-
sponding to the slits a, and by rotating it the air passages
are either made larger or smaller. The shutter is controlled
by the operator through a lever connected to the arm m.
By partly closing the slits, the relative amount of carbureted
air is reduced and a larger proportion of air is compelled to
enter through the valve e,

41. Carljureters With. Air Inlet Controlled by
Throttle, — In addition to the automatic carbureters just
described, there is a large class having the auxiliary air inlet
rigidly connected to the throttle so that the two open and
close together. This does not secure strictly automatic
action, because the speed of the engine varies with the load
as well as with the throttle opening. Nevertheless, it is
found in many cases to give exceedingly satisfactory results.

66600.T

CARBURETERS

gi:

An early form of such a carbureter, which, however, has
been little changed, is shown in Fig. 19 {a) and (*), {a) being a
top view and {b) a sectional side view. At a is shown the float
chamber; at ^, the spray nozzle; and at r, a choking device
equivalent to a needle valve, except that its end is blunt
instead of pointed; it is carried by a screw of coarse pitch, as
shown, and is raised or lowered to increase or retard the

:^..c

flow of gasoline from the nozzle by turning the screw by
means of the lever d. The principal stream of air is warmed
by passing around the exhaust pipes, and enters the annular
chamber e by the pipe ^, and, following the direction of the
arrows, it is drawn past the spray nozzle d and up into the
branch pipe /, which leads directly to the inlet valve cham-
bers of the engine cylinders. The auxiliary stream of ai-x"
enters by the slot // in the tube /. Inside this tube is a slot -
ted shutter or sleeve /, with the right-hand end closed an ^^
connected to the stem /. When the shutter is moved to tl»-^
left or right, it will partly cover or uncover the slot A, aa- <3
at the same time, by moWng to the left, it partially obstruents
the passage both of the carbureted air and of the auxiliar""^
stream of air before they pass into the pipes i6, /.

S17

CARBURETERS

48. In another carbureter, a by-pass controlled by a
throttle furnishes ,the auxiliary or diluting air stream. This
throttle is connected to the main throttle, but there is also a
valve controlling the entrance of the air to the spray chamber.
This valve, by lifting when the velocity of the air increases,
tends to keep the suction in the spray chamber more nearly
constant than would otherwise be the case. Fig. 20 shows

two sectional views of such a carbureter, the two views
being taken at right angles to each other. The intake for
both the main and the diluting air streams is shown at a.
Fig. 20 [ii). The spray chamber is greatly contracted about
the spray nozzle b, to give the air a high velocity, in order that
the gasoline may be drawn freely through the spray nozzle.
The air valve c is shown wide open. The auxiliary air stream
passes up through d, Fig. 20 (a), past the butterfly valve e,
which is controlled by the links and levers at f, attached to
the main throttle^, Fig. 20 {b). The passage of the gasoline
from the float chamber to the spray nozzle is controlled by
the needle valve h, which is regulated by the operator.

CARBURETERS

I 17

43. Central-Peed Carbureters. — The carbureter shown
in Fig. 21 has several advantages over the one shown in
Fig. IG. Instead of the spray chamber a and float chamber b

being entirely separate, the spray chamber is located inside
the float chamber. Br reason of this arrangement, the car-
bureter is not afEected by tilting, which might cause the

§ 17 CARBURETERS 43

gasoline to overflow from the spray nozzle or to require con-
siderable suction to lift it to the top of the nozzle. Also, the
needle valve Cy controlling the entrance of the gasoline to
the float chamber is closed by the weight on its stem, instead
of directly by the annular cork float d^ whose function it is
to raise the weight through the action of the lever e. As
the arm of the lever connected to the float is much longer
than that acting against the weight, a much more positive
closing of the valve is secured than if the float were to act
directly on the valve.

In this device, the throttle is made a part of the carbureter,
and is operated by the lever arm /at the top. The princi-
pal air stream enters at the bottom through the wire-gauze
dust screen^ and passes upwards past the spray nozzle.
The auxiliary stream enters by the automatic inlet valve A,
which opens downwards against the spring i. This valve is
composed of a fiber disk, with a brass bushing guided by the
stem of the screw j\ The threaded bushing k may be
adjusted to vary the tension of the spring i. The spray
opening is regulated by the needle valve /. The carbureter
is primed for starting by raising the stem m of the needle
valve. As the weight is attached to this stem by means of a
screw thread as shown, the weight may be screwed up or
down, and the level at which the float will act on the gaso-
line valve will be altered. For example, if it is found that
the float does not close the valve until the gasoline has
reached too high a level, it may be adjusted by screwing the
weight upwards on the stem, which will permit the valve to
close when the float stands in a lower position.

4:4« A section of a type of carbureter used in both auto-
nniobile and marine practice is shown in Fig. 22. It differs
from those previously shown in a number of particulars.
The gasoline enters at a and the air at by which in the car-
bureters previously shown would naturally be the outlet.
The air therefore flows downwards past the spray nozzle,
instead of upwards as is more usual, and passes through the
throttle valve and out at c. The float d is shaped so that it

CARBURETERS

Slf

goes on each side of the mixing chamber. It is secured to a
lever pivoted at the right, and rising closes the needle valves.
In the passage b is an automatic air-inlet valve _/i closed by
s of a spring g, as shown. This valve does not entirely

close the air passage when it rests against its seat, hut ^
the bottom is left an opening through which is suppli^'
the necessary air for keeping the motor in operation uni3-^
the slowest running conditions. As the suction increas*^^'
this valve opens against the spring g, thereby admitting" *
larger quantity of air.

The gasoline passes directly from the float chamber to tS^
spray nozzle //, the opening of which may be regulated by
the needle valve ('. As the opening of this nozzle is exactlj'
in the center of the float chamber, the carbureter is not

§ 17 CARBURETERS 45

affected by being tilted. The throttle valvey is opened and
closed by means of the lever k ; the mixture of air and gaso-
line passes through in the direction indicated by the arrow.
Adjustment of the automatic air valve / is obtained by
modifying the tension of the spring g^ by screwing up or
unscrewing the shouldered stem /, which extends through
the valve y* to guide it, but is not attached to it A drain
cock in is provided at the bottom of the float chamber, for
the purpose of empt)dng or for drawing off water that may
have got into it.

In starting the engine, the float d is depressed by means
of the lever «, which depresses the pin o. This allows the
level of the gasoline to rise above the nozzle A, when enough
gasoline enters the air passage to start the engine. This is
known as ^priming device.

CABBURETER AI>,TUSTM1!:NT

45. A carbureter may deliver too rich a mixture or too
weak a mixture, at all speeds within the range of operation
of the engine. More often, however, a mixture will be rich
at certain speeds, high or low, and either normal or, possi-
bly, too weak at other speeds; or it will be weak at high or
low speeds and normal or too rich when the speed is
changed. Owing to the large number of types of carbu-
reters, no definite rules that will apply to all can be made for
their adjustment. If the printed instructions of the maker
are at hand, they should be followed. If these should fail
to give the desired result, an observance of the following
general principles may aid in correcting the trouble.

1. A non-automatic carbureter will tend to take propor-
tionally more gasoline at high than at low speeds. If
adjusted correctly for low speeds, it will be wrong for high
speeds, and vice versa.

2. A needle valve acting on the spray nozzle does not
produce automatic regulation; it reduces or increases

46 CARBURETERS § 17

the gasoline feed in substantially the same ratio for all
speeds.

3. A fixed shutter over the air intake does not produce
automatic regulation. By partly closing it, the suction in
the spray chamber is increased and the amount of air sup-
plied is reduced, thereby increasing the richness while
reducing the volume of the charge.

4. To obtain a uniform mixture with a carbureter that
is not automatic, the gasoline feed at high speeds must be
restricted, or the air must be allowed to enter more freely,
to diminish the suction in the spray chamber. Some car-
bureters are arranged to by-pass a portion of the air around
the spray chamber at high speeds. If the by-pass valve
controlling this action is connected to the throttle, the type
of carbureter will be like those shown in Figs. 19 and 20.

5. In an automatic carbureter, opening the needle valve
or reducing the air-intake opening will give a richer mixture
at all speeds.

6. In an automatic carbureter, reducing the spring ten-
sion on the auxiliary, or diluting, air valve will permit this
valve to open wider, especially at high speeds, and will
therefore make the mixture weaker at high speeda The same
principle holds good regarding the spring tension on such a
device as the head or thimble, shown in Fig. 17, that per-
mits a portion of the air to pass around the spray chamber.
Increasing the spring tension makes the mixture richer at
high speeds.

7. A weaker mixture may be obtained at low speeds tj
increasing the spring tension on the automatic or auxiliaiy
valve and enlarging the main air intake ; or it may be
obtained by increasing the spring tension and partly dos-
ing the needle valve. The latter arrangement will not give
as full charges as the other, as the resistance to the ingoing
charge will be greater, but if the carbureter is large for the
engine it may give better vaporization on account of the
higher air velocity past the spray nozzle.

8. If at high speed richer charges are desired, thd thro^'
tling effect due to increasing the spring tension on tlw

§ 17 CARBURETERS 47

automatic valve may be offset by increasing' the opening of
the main air intake. The needle valve also should be opened
further, to avoid the necessity of restricting the automatic
valve unduly. At low speeds, the increased openings of the
main intake and the needle valve will neutralize each other
as regards the proportions of the mixture.

9. If the automatic valve is provided with a stop, its
effect will be to render the carbureter non-automatic at
speeds above those at which the automatic valve comes
against the stop. For this reason, reliance should be placed
on the spring where possible, rather than on the stop. The
chief function of the stop should be to prevent the valve
from opening under sudden pulsations so far that, by reason
of its inertia, it cannot close promptly.

10. A slightly weak mixture bums faster than a normal
or a rich mixture. This, therefore, is the best mixture for
high speeds. When, however, the motor is working under
a heavy load, a slow-burning mixture is better, as it main-
tains a higher pressure on the working stroke. The ideal
carbureter adjustment, therefore, should give a normal mix-
ture, or one very slightly rich, at the slowest speeds, and a
weaker mixture at high speeds.

11. Occasionally, a change in carbureter adjustment is

made necessary by a change in weather or in the quality of

the fuel. Such changes are properly made in the main air

or needle-valve openings, since the changes must be the

same for all speeds.

12. In order to have correct adjustment, the gasoline
level in the float chamber must be at or slightly below the
spray orifice.

46. Adjustment of Ne^v Automobile or Marine Car-
bureter. — In adjusting a new carbureter, the first thing to
^0 is to see that the gasoline level is at the right height,
^hich it probably is. If not, examine the float to see
* that it is working properly and is set correctly. Next see
^t the igniting device produces a good strong spark, and
^^ox follow the instructions of the maker regarding the

48 CARBURETERS | 17

setting of the needle valve, main air intake, and automatic
valve. Prime the carbureter freely, and start the engine.
Run it throttled to about half speed at first, with suitable
spark lead, and gradually reduce the opening of the needle
valve, a little at a time, until the engine shows signs of run-
ning weaker. Then open it to the point where the engine
runs best. If the engine starts, but will not keep on
running, it is getting either too much or too little gasoline,
probably the latter. The former will be indicated by black
smoke in the exhaust, and probably a very loud exhaust due
to slow combustion. If there is no black smoke, but the
motor will not run, try increasing the needle valve opening,
a little at a time, until the motor runs steadily, after which
adjust as before.

Now open the throttle a little, and note the result, as the
engine runs up to or a little beyond its maximum speed. If
it weakens, it is probably getting too much gasoline. Relax
the spring on the automatic valve, and try again. Watch
for black smoke, but remember that this appears only when
the excess of gasoline is considerable. If necessary, open
the needle valve and readjust the main air intake. Try also
closing the throttle until the motor barely runs, retarding
the spark, and note how quickly it responds as the throttle
is opened. A little further experimenting along the lines
just indicated will result in an adjustment suflBciently cor-
rect to allow the engine to be run in regfular service, after
which it is comparatively easy to discover what changes will
produce the best mixture.

»i

ELECTRIC IGNITION DEVICES

iQtNition systems

MAKi:- AMD-BREAK IGNITION

1. If the ends of two wires forming part of an electric
circuit are brought in contact, thereby closing the circuit,
and then quickly separated, a bright spark will be produced
as the contact is broken. This phenomenon underlies the
operative principle of what is known as the make-and-
break system of Igrnltlon, with which it is necessary first
to complete the electrical circuit through the spark-producing
mechanism, or Igrnlter, and then break the circuit to obtain
a spark for igniting the charge. In stationary gas-engine
practice, the simplest kind of igniter uses city lighting cur-
rent, with an incandescent lamp in series in order to pre-
vent the current from being too strong, and consists simply
of a mechanical device for making and breaking the circuit
in the combustion chamber at the proper moment.

2, In Figs. 1 and 2 is shown an elementary make-and-
^ak ignition device. In Fig. 1, a: is a shaft turning at
^'^•half the speed of the engine, or, if the engine is of the
^o-cycle type, it turns at the same speed, and may, in fact,
°^ the engine crank-shaft itself. On this shaft is a cam b,
'leqnently called a snap cam, that bears against a plunger
^» held in contact with the cam by the spring d. The upper
^^ of this plunger has an adjustable head ^, against which

^^^Mr^hM Jy Intematianal Textbook Company. Entered at Stationers^ Hall, London,

1 18

ELECTRIC IGNITION DEVICES

§18

bears a finger/, secured to a rocking stem g. This stem^
passes through the wall of the combustion chamber, and
near its inner end it has a ground flange to prevent the gases
from blowingpast it. The innerend
is prolonged in the finger k, that
makes contact with an insulated stem
1 /', to whose outer end one of the wires
' of the electric circuit is attached.
The light spring^/' holds the finger k
against the stem i, except when the
two are separated by the pressure
of the head e against the finger /
In Fig. 3 is shown a view of the
P^rts /, g, h, and i taken at right
angles to the view in Fig. 1. Because
the greater tension of the spring d
overcomes tliat of the spring/, the
contact points are normally out of
contact except when the plunger is
pushed upby the cam. The adjustment of the head e is such
that after contact has been made it leaves the finger/^ and
continues its upward motion a short distance, so that, when
the plunger snaps off from the cam, the head strikes the
finger a smart blow, thereby causing an abrupt separation of
the contact points. By reason
of this abntpt separation, the
contitct points are saved from t
being burned or fused by the
arcing of the current that would
otherwise occur. In spile of ^
this precaution, however, the
contact piiints deteriorate rap-
idly frrim the intense spark;

conscfjuently, an electric-light current is used for ignition
only when dilute g;is is use.! — such as producer or blast-
furnace gas, hi lib nf whii-h ignite with difhculty — or in large
engines, where reliability of ignitinu is of more consequence
than the burning of the contact points.

§18

ELECTRIC IGNITION DEVICES

3. Figf. 3 sliows an igniter plug for a stationary engine
as it appears when removed from the cylinder head. To
avoid corrosion and consequent sticking in the cylinder
head, the plug a, which enters the head, is usually made of
brass. It contains the stationary electrode b and the mov-
able electrode c, both being fitted with platinum tips at the
points of contact. The fixed electrode b is insulated from
the plug by means of bushings made of porcelain, lava,
mica, or some similar insulating material. If of porcelain
or lava, they are made
ti£fht against the pres-
sure of the explosion by
asbestos- packing wash-
ers between the faces of
the insulators and the
collar of the electrode,
the countersunk ptir-
tions of the plug in
which the bushings are
fitted, and the nut d
that holds the electrode
in place. The movable electrodes has a long stem e passing
through the plug, and has an interrupter lever /"fitted loosely
on it. A stop-lever^ is held firmly on the stem e by means
of a cotter h, passing through the lever and stem, and a
spiral spring ( fastened at one end to the interrupter lever/"
and at the other end to a pin passing through the extreme
end of the electrode stem e, the spring being twisted so as to
cause its tension to press the blade of the interrupter lever/
against the arm of the stop-lever^, A stop-pin / attached
to the inner end of the igniter plug limits the space between
the two points of contact when the electrodes separate.

The spark is produced by rotating the interrupter lever/
about the axis of the stem f to a point beyond that at which
the igniter points b and c are in contact. When these points
meet, the stem r ceases to rotate and the lever /and arm. ^
are separated, while some additional tension is also put in
the spring r. When the lever / is released, the spring i

ELECTRIC IGNITION DEVICES

Sl8

causes the lever to retnni,
striking the arm g a sharp blow
and causing- the igniter points
to be quickly separated, thus
producing the spark.

4. While, in application and
principle of operation, the
make-and-break igniters used
on diflEerent marine engines are
very much alike, they are very
dissimilar in details of construC'
tion. A front elevation and a
horizontal section of one form
of igniter used on a four-cycle
marine engine are shown in
Fig. 4 {a) and (*). The igni-
tion mechanism is operated by
means of an eccentric a that
actuates the igniter rod i. The
latter is attached to the arm c
of the movable electrode d by
means of a trunnioned block t
held in place by the yoke or
igniter hammer f hsA. the
springs^audA, the latter imme-
diately under the head-end j oi
the igniter rod, as shown. The
igniter trip, or latch, k is piv-
oted on the igniter-rod end j.
As shown in Fig. 4 (*), the
arms c are pinned to the outer
end of the stem of the movable
electrode d, whose contact arm
/ is provided with a ground bev-
eled scat or taper fit in the
ignilcrbonnet m. The station-
ary electrode « is insulated from

§ 18 ELECTRIC IGNITION DEVICES 6

the igniter bonnet by means of mica disks o fitted into recesses
in the igniter bonnet and held in place by a washer and
nuts /. On the contact arm / and on the inner end of the
stationary electrode ;/ are contact points, shown dotted in
Fig. 4 {a), of platinum, nickel steel, or other material that
does not oxidize readily under heat.

When the eccentric a moves in the direction of the arrow,
the igniter rod b will rise, carrying with it the yoke or ham-
mer y*, compressing the springs g and //, and lifting the
igniter block e so as to carry the inner arm of the movable
electrode into contact with the contact point of the station-
ary electrode and thus close the circuit Further upward
movement of the igniter rod serves simply to increase the
tension of the springs g and //, so that, when the horizontal
arm of the latch k comes in contact with the igniter pin y,
and the latch k is thereby thrown away from the hammer
yoke yj the latter will descend quickly on being released.
The rapid descent of the hammer / causes a sharp blow to
be struck on the igniter block e^ resulting in a quick break of
the contact between the movable and stationary electrodes,
and thus producing a spark that ignites the charge.

6. To run an engine at varying speeds, it is necessary, in
order to obtain the best results, to modify the time of ignition
to suit the speed, making the time earlier for high than
for low speed. It is also necessary to modify the time of
ignition, according to the load the engine is carrying, if the
engine is regulated by throttling. In other words, with a
given speed, a charge will bum faster if highly com-
pressed, as when a full charge is taken, than if only
slightly compressed, as it may be if the charge has been
much throttled. For these reasons, all automobile engines
and a great number of launch engines are provided with
means for varying the time of ignition. The time of
ignition can be varied with the primary ignition device
shown in Fig. 1, by pivoting the guide ^ at / and swinging it
a little to the right for a later spark, and to the left for an
earlier spark.

ELECTRIC IGNITION DEVICES

518

6, With the igniter mechanism shown in Fig. 4, the time
of ignition is regulated hy means of an adjusting lever r
operated by a horizontal rod s. Forward motion of the
lever r raises the threaded igniter pin y; while a rearward
movement lowers it, thus advancing or retarding the time
of tripping the latch k and hence the time of ignition.

7. Of many simpler devices than this, it is necessary to
mention but one type, operated by a straight spring-returned
igniter rod that, in turn, is actuated by a cam of any desired

shape. The igniter rod passes through a flat rocker lever.
There is a flat washer on each side of the roclcer-arm.
with springs hold by collars or threaded nuts above and
below. In action, the igniter rod rises, and the rocker-
arm, washers, and springs assume the position shown in
Kig. 5 ((?) when the contact within the cylinder is made.
The rod continues to rise until it is tripped at the time of
i^ition by any suitable means. The rod, lever, springs, and
washers then assume their normal positions, the igniter points

§18

ELECTRIC IGNITION DEVICES

separate, and ignition takes place. Fig. 5 (d) shows a modi-
fied form of this simple ignition mechanism.

In a large number of two-cycle marine engines on
the market, the insulated electrode is not mounted in a
removable bonnet with the moving electrode, the usual con-
struction being to have the insulated electrode inserted
through the cylinder head.

8, With a low- voltage current, such as that derived from
a pnmary battery, a spark coil must be employed to produce
the necessary electric tension or voltage for the spark.
When a battery and spark coil are employed, the abrupt-
iiess of the break between the contact points serves to
increase the intensity of the spark, it being largely propor-
tional to the sharpness of the circuit rupture. In Fig. 6 is
shown an elementary wiring
diagram for a primary igni-
tion circuit, with the direc-
tion of the current shown by

^'Tows. When the timing

^'^ni a brings the points ^ and

^ into contact, the current

flows from the battery d

through the switch e (when

^Josed), the spark coil /, the

insulated electrode ^, the

locking contact finger //, and the grounded contacts /,/, back

^o the battery. The grounded connections /, t may be made

^0 the frame of the machine, or any other convenient metallic

^turn may be used.

JUMP-SPARK IGNITION

&• The mechanism of the makc-and -break system of igni-
tion requires a considerable number of moving parts that arc
naore or less objectionable in an automobile engine, and the
^ority of automobile builders prefer to use what is known
2S the jump-spark system of ignition, in which the primary
current is converted by. an induction coil into a secondary

ELECTRIC IGNITION DEVICES

§18

current of sufficiently high tension to cause a spark to jump
an air gap. With this system, a revolving contact timer is
employed in place of the snap cam b shown in Fig. 1. As
there are no other moving parts, the virhole apparatus is
extremely simple.

10. In the diagram. Fig. 7, are shown the essential ele-
ments of a jump-spark system of ignition. Here a is the
battery, ^ is a switch for opening the primary circuit when
it is not in use, and ^ is a revolving timer turning at one-half
the speed of the crank-shaft, if the engine is of the four-cycle

^=a@|p,

W5WS

Fn;. :

type. The timer in the elementary apparatus shown consists
of an insulating ring d mounted on the shaft and having
dovetailed into it a copper or brass segment ^, in electrical
connection, by a screw or otherwise, with the shaft y. A
plate g is mounted loosely on the shaft, so that it does not
turn with it, but may be rocked about it through a suitable
arc, say 4r>'^. Mounted on this plate, and insulated from
it, is a brush //, that bears against the insulating ring and
makes contact with the metal segment at each revolution of
the latter. The primary winding of the spark coil is
represented by /, and / is the groimd on the engine.
A trembler h, similar to an electric buzzer, is provided so
that the current may be rapidly interrupted. The trembler

§ 18 ELECTRIC IGNITION DEVICES 9

is exactly like the interrupter or vibrator of a Ruhmkorff
coil, and its purpose is both to interrupt the current more
rapidly than could be done by the timer and to produce a
stream of sparks instead of a single spark only.

11. The course of the current is from the positive pole
of the battery to the trembler, then to the primary winding of
the spark coil, the engine frame y, through e to the brush of
the timer, when contact is made, and finally through the
switch b to the negative terminal of the battery. The negative
terminal of the secondary winding of the coil is connected to
the battery terminal of the primary winding, and the posi-
tive secondary terminal is connected to the insulated mem-
ber of the spark device, or spark plug:, from which, after
jumping over the gap /, the current returns to the coil by
way of the engine frame/ and primary winding. When the
circuit is closed by the timer, a stream of sparks passes
between the spark points /. For use with small, high-speed
motors, the coil vibrator is frequently omitted, and a snap
or vibrating form of timer is used that gives a quick break
but only one spark.

12. As in the RuhmkorfiE coil, the primary winding is
provided with a condenser ;//, which serves the double pur-
pose of increasing the abruptness of the circuit rupture,
thereby increasing the intensity of the secondary spark, and
of absorbing the current that otherwise would produce a hot
spark at the trembler contacts, and soon bum them out It
will be remembered that the function of a condenser is to
absorb the extra current induced in the primary coil at the
moment of rupture. Under the primary system of ignition, it
is precisely this extra current that produces the useful spark
in the engine; but in the secondary system, this extra current
is objectionable, because it dies down so slowly that it fails
to induce a sufficiently intense spark in the secondary coil.

The change of the time of ignition is accomplished for
difEerent speeds by rocking the plate g to the right or left by
means of the rod », so that contact is made by the timer
early or late in the revolution of the shaft.

10 ELECTRIC IGNITION DEVICES § 18

COXSTRXJCTIOX Al!n> APPLICATION OF

IGNITION DEVICES

BATTERIES

PBIMARY BATTBRFES

13. With small engines, the source of the ignition ctirrent
is commonly a battery, which may be primary or secondary
according to conditions. If the engine is stationary, the
battery is commonly an Edison- Lalande or other oxide-of-
copper battery. For marine motors, storage batteries are
sometimes used, and sometimes also the oxide-of-copper
batteries, but the most common source of current is the
dry cell, which is now made in certain forms with very high
efficiency and long life. For automobiles, the battery is
either of the primary dry-cell type just mentioned or of
some special type of storage battery.

14. When dry primary cells are used, the number neces-
sary will depend on the winding of the spark coil and the
size and condition of the cells. Some coils wotmd for dry
primary cells require a higher voltage than others, and the
internal resistance of the cells has also a considerable influ-
ence. Dry primary cells can now be obtained that, even in
the small, or 6-inch size, i. e., measuring 6 inches in height,
will, when fresh, test over 25 arnperes on short circuit
Of these fresh cells, generally four or five, sometimes even
three, will be found sufficient; but, as they approach exhaus-
tion, one, two, or three more must be added. The first cells
of the set are thrown away when spent, and fresh ones put in
their place, while the last cells are still useful. A good

18 ELECTRIC IGNITION DEVICES 11

rangement is to have two sets, of from five to eight cells
ich, arranifed so that current may be taken from either set

While four dry-battery cells when new will ignite the
lai^, it is customary to use from six to eight cells. With
-oper care and adjustment to the proper length of contact
>r make -and- break ignition, a set of cells in a motor boat
ill sometimes last two seasons or more, while dry cells acci-
intally short-circuited and left 2 or 3 hours will be ruined.

No matter what type of battery is used, in motor boats
r elsewhere, the cells should be kept dry, and a reserve set
oould always be kept on hand for use in case of failure
rom any cause, A very large proportion of drifting boats,
Dmetimes in dangerous places, are disabled as a result of
xhausted batteries.

CASE OF FRtMARY BATTBRIES

16. The only care a primary drj- battery requires is to test
t occasionally with an ammeter to determine the condition of
te cells. This should be done cite cfU at a time, with a
wket ammeter such as is shown
a Pig. 8. The instrument is
ised by touching the part marked
arhon to the carbon (positive)
erminal of the battery, and the
nsulated cable a to the zinc
negative) terminal, which short-
inniits the cell. The particular
nstrument shown indicates both
Hits and amperes, the latter '^^^illSlit^
■nly when the button b is pressed,
'he button should be pressed for "'■

1 instant only, barely long enough to allow the needle to
)me to rest, as the battery is very rapidly depleted by
lort-circuiting.

Occasionally, the battery box used on automobiles for
■Iding the cells should be opened and the nuts of the bind-
% posts tried with the fingers to see that they have not

13 ELECTRIC IGNITION DEVICES §18

worked loose. It is well also to examine the flexible bat-
tery connectors, since, if these are of the ordinary ready-
made sort, they are probably too short to have sufficient
flexibility unless the battery cells are packed very tig-htly, so
as to entirely prevent them from shaking. Any vibration
of the cells will, in time, break the connectors. As this gen-
erally occurs inside the insulation, it is a difficult thing to
locate, and it is best detected by substituting a fresh con-
nector for any one that, when tried by bending it in the
fingers, appears to be broken.

16, Good battery connectors may be made up from
No. 16 flexible lamp cord in 8-inch lengths. The cord is
imtwisted for the purpose, and each length makes two con-
nectors. The ends of the cords are scraped for a length of

about 1 inch, and the bairb wire
twisted and doubled on itself. The
wire is then slipped through a ter-
minal or copper connector of the
form shown in Fig. 9, the bare end
being run through the stamped
^^^" " loop a. The loop is then ham-

mered flat, the wire doubled back upon itself, and the clips
by b bent over the insulated part of the wire with a pair of
pliers. The wire is then coiled around a lead pencil.

If the binding posts on the battery cells show a tendency
to work loose, the nuts may be locked with nuts taken from
discarded cells. If, however, the wire connections are flex-
ible, such as those just described, and the cells do not shake
about, there will be little tendency on the part of the nuts
to work loose.

17. In testing a primary battery, it should be remem-
bered that on standing the cells will recuperate sufficiently
to show on test a strength apparently sufficient for a consid-
erable mileage; but if they are nearly discharged they will
go down again in a few miles and cause the engine to miss
explosions apparently without reason. If there is reason to

818 ELECTRIC IGNITION DEVICES 13

think that the battery is nearly spent, the cells should be
tested after the car has been run 5 or 10 miles. If they
show less than 5 amperes on short circuit they are not worth
keeping, unless the spark coil is very efficient Since a
primary battery will recuperate somewhat on standing, the
possession of two sets of cells, both of which are nearly
exhausted, enables the operator to keep the engine going
for some time by switching alternately from one battery to
the other. When that expedient fails, the two sets may be
recoupled in series and used a little longer.

S£CON1>AItT, OR STORAGE, BATTERIES

18. The majority of the storage batteries used for igni-
tion purposes are similar in construction to those used for
vehicle propulsion, but of smaller capacity; but there are
also a few dry storage batteries in which the acid solution is
mixed with silicate of soda, by which is produced a sort of
jelly that is not subject to the risk of spilling. When liquid
cells are used, they are, of course, sealed, and have a rubber
screw plug in the top with a small vent through it for the
escape of gases produced in charging. By unscrewing the
plug, a syringe can be introduced to take out a portion of
the liquid for the purpose of testing its density with a
hydrometer.

The storage-battery equipment of an automobile almost
mvanably consists of two sets of two cells each,but occasionally
three cells are used. The negative terminals of both sets
are connected together, and the positive terminals lead to
independent terminals on a two-throw switch, so that either
battery may be used at will, while the other is held in
reserve until the first is discharged.

19. When a storage battery Aveakens to such an extent
that explosions are missed, it can no longer be xised until
recharged, for storage batteries do not recuperate when put
out of service and allowed to stand. A storage battery dis-
charges itself slowly, and when it is partly discharged it

14 ELECTRIC IGNITION DEVICES §18

loses its strength much more rapidly than when Mly
charged. For this reason, a storage battery should be used
continuously until it is discharged before the other battery
is put into service. A storage cell is discharged when its
voltage on open circuit has dropped to 1.8 volts. Down to
this point the voltage ^vill drop rather slowly, but with
increasing rapidity as the end is approached, and from 1.8
the voltage falls off with extreme rapidity.

A storage battery is tested by testing its cells individually
with a voltmeter, an ammeter being useless for this pur-
pose, and it should be recharged as soon as the voltage of
either cell has fallen to 1.8. It i% in fact, best to recharge
a little sooner than this, in order to avoid being unexpect-
edly stranded, and for this purpose the battery should be
tested regularly once in from 100 to 200 miles. ' It is well also
to test the battery in reserve at the same time, to see how fast
it is losing its charge. The voltmeter used should also be
tested occasionally by comparison with an instrument of
known accuracy, else its reading is likely to be misleading.

20, In places where no direct current is available, but
where alternating current can be obtained, storage batteries
for ignition purposes or for use in electric vehicles may be
charged through the use of what is known as a mercury-
vapor converter, a comparatively simple device for con-
verting alternating to direct current without using vibratory
or rotating mechanism.

CARE OF STORAGE BATTERIES

21. The following are general directions for the care of
ignition storage batteries: The electrolyte or acid solution
should always cover the tops of the plates to a depth of
about \ inch. Replace with fresh solution any loss by spill-
ing, but use distilled water where the loss is due to evapora-
tion. Use only chemically pure sulphuric acid. The pro-
portion of acid to water is about 1 to 6, by liquid measure, at
G0° F. Use a glazed-stone vessel for mixing, and add the acid
to the water very slowly^ while stirring with a glass or hard-

S 18

ELECTRIC IGNITION DEVICES

rubber rod, the purpose being to distribute evenly through-
out the mixture the heat generated as the acid and water
mix. The water must never be pourediiito the acid^ for the
reason that, being lighter than the acid, it would flow
quickly over the top of the acid, and the rapid generation of
heat would quickly transform the water into steam and
cause both water and acid to be thrown violently from the
containing vessel. When the electrolyte is cool,
it should be tested with a hydrometer, such as
that shown in Fig. 10, which shows a style of
hydrometer designed for use in liquids heavier
than water and one that is particularly adapted
for use in testing the cells of automobile bat-
teries. The hydrometer a is placed within the
glass tube ^, and by means of the rubber bulb
sufficient electrolyte can be drawn i;ip to float the
hydrometer. Enough liquid is drawn up to fill
the tube up to the mark d ground on the glass,
and the reading is taken at the point where the
floating tube a emerges from the liquid. On
test, the hydrometer should read between 20®
and 25° Baum6, or 1.1 02 to 1.2 specific gravity.
When the battery is fully charged, the electrolyte
should be about 30° Baum6 or 1.26 sp)ecific grav-
ity. If the specific gravity is low, remove some
of the liquid with a rubber syringe bulb and add
a stronger solution, not exceeding 1,4 specific
gravity or 41° Baumd. If too high, add distilled
water until the proper density is reached.

When setting up new cells, pour through the
holes in the cover, by using a funnel of glass or hard rub-
ber, sufficient sulphuric-acid solution to cover the plates fully,
and charge the battery immediately.

Whenever the battery is to be charged, remove the vent
plug from each cell to allow the gas to escape. Care should
be taken not to bring a naked flame near these openings
while charging, as the gases given off are hydrogen and
oxygen, and are highly explosive when mingled.

PlO. 10

16 ELECTRIC IGNITION DEVICES § 18

The completion of the charge is indicated, first, by a fine
boiling or discharge of gas sometimes called ^assin^^ which
gives to the liquid a kind of milky color, and, second, by the
voltage, which must be near to 2^ volts per cell, the test
being made during the charge. If a voltmeter or hj'drom-
eter is not available, the charge should be continued until
each cell has been gassing, or bubbling, about 20 minutes.
Do not prolong the charge beyond this limit Cells should
never be allowed to stand discharged, but when discharged
should be recharged immediately.

33. Direct current only, never alternating, should he
used for charging. Be sure to connect the positive wire of
the charging line with the positive pole of the battery, as
otherwise the battery may be ruined. If there is no volt-
meter at hand to determine which wire is positive, attach a
piece of lead to each wire, and immerse both in a small
quantity of the electrolyte, but without allowing them to
touch each other, when the positive piece will turn brown.

Always place sufficient resistance between the positive
terminal of the charging line and the positive pole of the
battery to make the voltage, as measured between the
charging terminals, when the battery is connected, not more
than 25 per cent, greater than the rated battery voltage, or
5 volts for a 4-volt, or two-cell battery.

23. The battery should be charged at a rate determined
by its capacity in ampere-hours, the charging current, in
amperes, being equal, for an ordinary battery, to the am-
pere-hour capacity divided by 10. Thus, a 65-ampere-hoar
l)atter>^ should be charged at 6.5 amperes or an 80-ampere-
hour battery at 8 amperes. Another and perhaps better
rule is to charge at a rate not exceeding one-eighth or one-
sixth of the ampere-hour capacity, and maintain this rate by
gradually cutting out resistance until the voltage reaches
2.4 or 2.5 per cell, when the cells begin to gas; then cut
down the chargin<f current to one-twentieth of the ampere-
hour capacity until the cells again gas freely, indicating a
full charge.

§ 18 ELECTRIC IGNITION DEVICES 17

If the battery is charged from an incandescent-light cir-
cuit, there must be used in series with the battery a resist-
ance sufficient to absorb the greater portion of the voltage
of the charging circuit. For this purpose a bank of lamps
is generally employed. As the internal resistance of the
battery is so small as to be almost negligible, it follows that a
100-volt lamp must be used for each 100 volts tension of the
charging current, or a 110- volt lamp for a 110-volt current.

24. Wiring connections for charging storage batteries
from direct-current lighting and power circuits are shown
diagrammatically in Fig. 11 (a), (b), (r), and (d). Connec-
tions to a 110-volt lighting circuit are shown in Fig. 11 {a),
A c3ouble-pole switch a, with fuses ^, is connected between
the mains and the battery as shown. In series with the bat-
tei-y r is a nvunber of lamps, by means of which the charg-
^^fir current is limited to the proper amount. It is advisable
^o c^onnect an ammeter d in circuit, though this is not abso-
^^t:ely necessary. The number of lamps required depends
^^^ the line voltage and on the charging rate of the cells. If
^he line pressure is 100 to 120 volts and but three or four
^^lls are to be charged with a current of 5 amperes, then
^V"e 32-candlepower lamps requiring 1 ampere each, con-
^^oted in multiple, as shown in Fig. 11 (a), will be suffi-
^^^t If 16-candlepower lamps requiring \ ampere each are
^s^d, it will be necessary to connect ten in parallel. With
^ 5J20-volt circuit, there will be required twice as many
*^ii3ps as with the 110-volt circuit, the second set of lamps
^^& placed in series with the first. If the line pressure is
SOO volts, it will be necessary to connect twenty-five 32-can-
dlepower lamps in five rows of five lamps in series in each
ro-^^ or fifty 16-candlepower lamps in ten rows, five lamps
^ Genes in each row as shown in Fig. 1 1 (^). In case it is con-
venient to charge at a lower rate, fewer rows of lamps will be
^^^ed, but the time for charging will be proportionately
i^^creased.

86. Lamps form a convenient resistance, as they are
^^jr obtained, but an adjustable rheostat is frequently used,

ELECTRIC IGNITION DEVICES

§18

as shown at r, Fig. 11 (c). The amount of resistance required
in the rheostat can easily be obtained as follows: Let Nht
the number of cells to be charged in series, then 2 -A^ will be
the approximate voltage for charging, since each cell ihay

±_

itf / H H {

(aj

(bj

■f

(e)

Ftg. 11

(dj

be taken as requiring 2 volts at the beginning ot the cha
If ^ is the line electromotive force, then £" — 2 TV is the nt-'*^
ber of volts effective in forcing current through the cira't-'
because the electromotive force of the cells is opposed to tt^

g 18 ELECTRIC IGNITION DEVICES 19

of the line. If / is the charging current, then the resistance
of the circuit will be

R =

and this will be practically equal to the amount of resistance
required in the rheostat, because the resistance of the cells
is very low.

Example. — Tweiity storage cells are to be charged from a 220-volt
circuit; how much resistance should be connected in series with them,
if the charging current is to be 5 amperes ?

SoLin ION. —Here E = 220, N= 20, and / = 5; hence, applying the
formula,

220 — 2 V 20
jR = ^^ = 86 ohms. Ans.

This resistance should be adjustable, so that some of it can ^ cut
out as the voltage of the cells increases, and it must be made of wire
large enough to carry at least 5 amperes without overheating.

Charging with resistance in series is at best a makeshift,
because it involves a large loss of energy; but in the case of
small, portable batteries, this waste is not a very serious
matter, especially as the use of the series resistance gives
the most convenient and simple means of charging from
existing circuits.

36. Sometimes cells are charged from constant-current
arc-light circuits, •but the practice is dangerous, and this
source of charging current should never be used if any other
is available. Constant-current arc-light dynamos generate a
very high pressure, and, as arc- light lines are nearly always
grounded to a greater or less extent, there isqtiite an element
of danger in working around a battery that is being charged
from such a source. Great care must be taken to see that
the arc-light circuit is not opened when the battery is being
switched on and off. This method of charging is shown in
Fig. 11 {d), where /, / represent arc lamps. In this kind of
circuit, the current is maintained at a constant value, usually
from 6 to 10 amperes, so that when the battery is to be charged

20 ELECTRIC IGNITION DEVICES § 18

it must DC placed in series with the lamps. The battery is cut
into circuit by means of a special switch, called a consumer s
s^vitchy which is constructed so that it will neither open the
circuit nor short-circuit the battery. This is done by means
of a contact point c connected to a resistance r.

When the switch blade is moved to the dotted position,
the resistance is first placed in series so that the line is not
opened, and at the same time there is no short-circuiting of
the battery. It will be noticed that, when the switch is in
the dotted position, the resistance is in parallel with the bat-
tery, so that part of the main current is shunted around the
battery. For example, the main current might be 9 amperes
and the required charging current 5 amperes, in which case
the resistance should be such that the difiEerence between the
two, i. e., 4 amperes, will flow through it. The pressure
between the terminals of the resistance is equal to the elec-
tromotive force of the cells ; hence, if / is the current shunted
through the resistance, E the voltage of the series of cells, and
R the resistance, then R is easily obtained from the relation

27. When charging a battery from any source, especially
when there is any doubt as to the direction of flow of the cur-
rent, a test should be made to determine whether or not the
positive plates are connected to the positive pole, so that the
current flows in at this pole when the battery is charging.
A simple method of doing this is to attach two wires to the
mains, connect some resistance in series to limit the current^
and dip the free ends into a glass of acidulated water, keep-
ing the ends about 1 inch apart. The end from which
bubbles of gas are given off most freely is connected to the
negative main, so that the main to which the other end
connects is the one to be attached to the positive pole of the
battery. Another convenient method of testing the polarity
is by means of a Weston voltmeter, or any instrument of
similar type, which will give a deflection over the scale

§ 18 ELECTRIC IGNITION DEVICES 21

only when the voltmeter terminal marked + is connected to
the positive line.

The positive terminal of a storage battery is usually
marked +, and is sometimes painted red. The positive
terminals of the two cells commonly installed on automobiles
and motor boats should be connected by separate wires to
the two terminals of a double-throw switch located in an
accessible position.
•

28. If a voltmeter or hydrometer test of a single cell of
the battery shows it to be out of order, it should receive
individual attention until it is restored to proper condition.
If the density of the solution is incorrect, it should be altered
as already indicated. If the voltage of one cell is low when
the rest are charged, cut it out and recharge it separately.
If the cell still fails to come up to the proper voltage, it is
likely to be due to the presence of active material that has
detached itself from the plates and fallen to the bottom, where
it may have bridged the space between two plates, thus short-
circuiting the cell. The novice had better not attempt to med-
dle with a battery in this condition, but with some electrical
experience one may remove the pitch with which the top of
the battery is sealed, and, taking off the hard-rubber cover
beneath, lift out the battery plates and wash them in cle^n
water.

The battery jar also should be emptied, cleaned out, fresh
aoid solution put in, and the plates put back in the acid as
soon as possible. The battery may be sealed up again by
naelting the pitch and pouring it over the cover, taking care
iK>t to stop up the vent hole. If the battery terminals
l>^^XMne dirty from acid creeping up on them, clean them
^v^th ammonia and a tooth brush. Ammonia may also be
^s«d to neutralize acid that may be spilled or that may get
^*'*^ the clothes or fingers, but to be effective it must be
^-Pplied immediately.

29» When the battery is not to be used for some time, it
**^y be laid up by one of the two following procedures,

22 ELECTRIC IGNITION DEVICES § 18

which are those recommended by the National Battery Com-
pany for their cells, and are equall)c applicable to others.

First Method. — When, for any reason, a battery is not to
be used for some length of time, it may be kept in good con-
dition by giving it an occasional freshening charge. This
charge should be given at intervals not greater than 2
months, and preferably once in every 6 weeks. The fresh-
ening charge should be at the rate of one-twentieth of the
ampere-hour capacity of the battery, and should be contin-
ued until the battery gases freely. This is by far the sim-
plest and the best way to tkke care of a battery when it is not
in actual service, as it will always be ready for immediate
service when needed. When a battery cared for in this man-
ner is again placed in service, the additional precaution may
be taken to give it the three-quarter discharge and the
charge following, to insure the full capacity, as described in
the second method.

Second Method. — If a battery is not to be used for some
time, and cannot receive an occasional charge to keep it in
good condition, it should be put in dry storage. To put a bat-
tery in dry storage, it should first be fully charged and given
an overcharge ; then the electrolyte should be emptied out
and the cells allowed to stand until the negative plates begin
to steam, which will be within about half an hour.

The next step is to cool the plates. Fill the cells with dis-
tilled water, and allow them to stand for about 10 minutes;
then pour out the water, and again allow them to stand
until the negative plates steam quite freely. This operation
should be repeated until the plates lose their heat.

Next put in the acid solution that was removed, and allow
the cells to stand for 1 hour, after which again remove the
solution and put the battery away in a dry place where the
temperature will not get below the freezing point.

After the last process, in which the plates are allowed to
soak in the acid solution for 1 hour, they should be watched
for a day to see that they do not again become heated. Should
it 1^ found that they are heating, the acid-soaking process
should be repeated until there are no more signs of heat.

§ 18 ELECTRIC IGNITION DEVICES 23

While the plates are still drying, it is possible that night-
fall may come on. The condition of the plates may still be
such as to make it inadvisable to leave them. If inconve-
nient or impossible to continue the above process during the
night, fill the cells with acid and allow them to stand until
morning, when the process may be continued.

30, To put these cells again into commission, fill them
with an acid solution having a specific gravity of 1.21, free
from impurities, and charge at the minimum rate as stamped
on the name plate until fully charged. This will require
about 40 hours. During this time, the battery should be
watched closely, and the temperature of the acid taken occa-
sionally. If the temperature should get above 100° F., the
charging current should be cut off for a few hours and the
cells allowed to cool; then the charge should be continued at
the minimum rate until the cells have been charged for 40
hours. It would then be strongly advisable, in order to
injure the full capacity of the plates, to give the cells about a
three-quarter discharge; then charge them again as before
until they gas freely, when the battery will be ready for
service.

The simplest way to secure a three-quarter discharge,
where the battery is being charged through a lamp circuit,
IS to reverse the connections of the battery, that is, connect
the negative charging wire to the positive terminal of the
battery and the positive charging wire to the negative ter-
minal, and allow the battefy to discharge until the voltage
has fallen to about one-quarter that at full charge.

This discharge should'be conducted at a rate of one-tenth
the capacity of the battery. If, for example, the capacity
of the battery is 40 ampere-hours, this discharge should be
carried on at a 4-ampere rate for a period of about 7 hours.
The battery connections should then again be reversed, and
a charge carried on at the minimum rate until the battery
gfases freely. It is better not to make a practice of recharg-
ing* storage batteries when they are less than half discharged.

24 ELECTRIC IGNITION DEVICES § 18

BFARK COIXiS

CONSTRUCTION AND OPERATION

31. In their application to the marine engine, spark
colls are broadly divided into two classes: the ordinary
inductance coil using the primary current only, and the
double-wound jump-spark induction or Ruhmkorff coil, in
which a secondary current of high potential is induced and
strengthened by means of a condenser, usually placed within
the coil box, or a condenser is provided for each coil; some-
times the circuit is so arranged that one condenser may b&
used with several coils.

Induction coils are of various shapes and types, and ordi-
narily are from 6 to 10 inches in leng^, rarely longer, and
their construction and operation are so well known as to
need no extended description here, ^hey should be kept
as dry as possible, even though they are usually protected
from dampness by means of paraffin wax, shellac, or similar
substances.

33, Coils used in high-tension or jump-spark ignition
are of two general classes, one with a vibrator that opens
and closes the secondary circuit and is actuated by the elec-
tromagnetism of the iron core of the coil, and the other with
no vibrator. The former gives a rapid succession of sparks,
and is the type used for the most part in jump-spark igni-
tion ; while the other, which is rarely met in marine prac-
tice, gives a single large spark on breaking the circuit
This latter type is used for the most part in motor-cycle
work where minimum weight is essential.

The object of primary ignition will be referred to latet in
connection with magneto-generators, with which it is prin-
cipally used. Where batteries are used, the jump-spark
system is almost invariably employed.

33. Fig. 12 shows the appearance of a typical jump-
spark coil for one cylinder. It is a standard four-terminal

ELECTRIC IGNITION DEVICES

, in whicli the binding posts a and h are, respectively,
positive and negative of the secondary coil, and the
ing posts c and d connect, respectively, to the engine
! and the battery. Posts b and c may be connected

together, since both are grounded. The fiat vibrator or
trembler spring e is adjusted with respect to its tension
by the screw_/i and g is the customary platinum-tipped con-
tact screw against which the vibrator works.

In Fig. 13 are shown the connections to a coil o£ this t?pe.

The secondary, or spark-plug, terminals are shown at a and
b, the current flowing from a to the insulated electrode of
the plug, returning from the grounded electrode of the
plug' to the groiuided terminal b, which may be connected

ELECTRIC IGNITION DEVICES

§18

to the negative terminal of the primary winding of the
coil. Through the wire c^ current flows to the coil from
the battery rf, when the switch e is closed and the insulated
member of the timer/* is in contact with tjie grounded mem-
ber of the timer, the direction of the current being indicated
by the arrows. The switch may be placed either between
the negative terminals of the battery and the timer, as
shown, or between the primary terminals and the coiL

34. In Fig. 14 are shown, diagrammatically, the connec-
tions of the coil shown in Fig. 12, the switch this time being
located between tHe batteries and the coiL Two batteries

PlO. 14

tf, a are shown, either of which may be used by taming the
switch d. The passage of the current is through one or the
other of the batteries a, a^ through the switch ^, primary
winding r, vibrator rf, contact screw e^ insulated member of
the timer/, and finally into the engine frame, as indicated
by the ground ^^ from which it returns to the negative

8 ELECTRIC IGNITION DEVICES 27

minal of the battery. The secondary winding is shown

4. As the secondary current is induced on rupture of
I primary, its direction is the same as that of the primary,
ich makes terminal i the positive. The negative termi-

j of the secondary winding is shown with an independ-
: ground connection g^ but it might equally well be con-
:ted to the primary winding, in which case the current
uld return to it through the battery and switch. This
•ticular coil has two condensers: the regular condenser ky
ich is found on all jump-spark coils, and which absorbs
extra or selfi-induced primary current at the moment of
)ture ; and another condenser /, which comes into play in
e the engine speed outruns the speed of the vibrator, and
latter sticks — that is, refuses to work fast enough to
p time with the engine. If this occurs, the only rupture
hat taking place at the timer, and the extra current then
s to the condenser / by way of the ground g on the
ine frame, and the wires m and «, there being then no
ik at the vibrator.

5. The feature discussed in the last article is not found
all coils, but it is useful with a high-speed engine, as
it coil vibrators, on account of their inertia, do not work
ibly at engine speeds exceeding 1,200 to 1,400 revolu-
s per minute. Of course, the rupture at the timer
irs somewhat later than at the vibrator, since the latter
ars soon after the timer makes contact; and, therefore,
he critical point when the vibrator begins to stick, the
er will need to be advanced in order to get the same
rk time. With a little practice, the operator learns to
>gnize the point to which the timer must be advanced.
is shown a safety spark gap^ as it is called, which is pro-
ed inside the case of all spark coils to prevent overstrain-
of the insulation, in case an abnormally severe current is
t through the coil. This gap is provided with a pair of
es soldered to the bottom ends of the binding posts a and
?ig. 12, and is about ^ inch long, that being equal to the
atest air gap that the spark is ordinarily required to

ELECTRIC IGNITION DEVICES

§18

jump. This is equivalent to about ^ inch under average
compression.

36. Every spark coil requires occasional attention to
the contact points of the trembler, as these become worn
and pitted under the large currents often employed. Spe-
cial means are commonly used to prevent the adjusting
screws of the trembler from working loose. In the coil
shown in Fig. 12, these means take the form of clamp screws
//, by which the split yoke in which the contact screw g is
threaded may be drawn tight on the screw. As the adjust-
ment must be very accurate, and the vibration of the trem-
bler quickly brings to light any looseness, some such provi-
sion as this is very necessary.

37. A special form of trembler, found on some French
coils, is shown in Fig. 15. For comparison, Fig. 16 shows

liUIUIili
lilUJIilli

liUUIIIIi

Fig. 15 Flo. 16

the hammer trembler of the ordinary coil. It will be
noticed that, in the latter, contact between the trembler
spring a and the screw b is broken almost instantly when
the hammer begins to move, the only delay, after the ham-
mer is in motion, being that required to allow the current
to build up in the coil, and to allow the hammer head to
travel as far as the yield of the spring will allow before the
rebound of the spring carries it toward the core c. As the
hammer head is quite heavy, it is evident that there is a

§18 ELECTRIC IGNITION DEVICES 29

limit to the speed of the vibrator, due largely to the inertia
of the head. The trembler shown in Fig. 15, on the other
hand, consists of a pair of flat steel blades, which, while not
so hard as to retain much permanent magnetism, are still
hard enough to act efficiently as springs. The lower spring
a is supported in the usual manner, and the upper spring b
is riveted to it at the point c. Normally, the blades sepa-
rate slightly, and the upper one makes contact with the
screw d. Consequently, when the circuit is closed, the
lower blade a is first attracted, and it moves downwards;
while the upper one, by virtue of the initial spread between
the blades, remains in contact with the screw. When, how-
ever, this spread has been fully taken up, the upper blade is
pulled out of contact by the continuing motion of a ; and, as
« has by this time acquired a considerable velocity, the sepa-
i^tion between b and d is very abrupt, thus causing an
energetic excitation of current in the secondary coil. By
reason of the extreme lightness of these springs, and
^cause of the fact that contact is maintained for a consid-
erable fraction of the working period of the trembler, the
speed is exceedingly high, without sacrifice of efficiency,
^d without preventing the magnetism from adequately
"Elding up between breaks.

CABE OF SPARK COILS

38. The care of the spark coil is limited to seeing that
the vibrators are kept clean and properly adjusted. The
platinum points of the contact screw should be kept flat and
clean, and to this end the contact screw should occasionally
be taken out, and both contacts dressed with a fine file. If
the adjustment of , the contact screw against the spring is too
tight or too loose, the operation of the coil will be erratic,

and in the former case the demand for current will be

excessive.

39. Most coil vibrators now made have two adjust-
ments: one for spring tension, involving also the distance

30 ELECTRIC IGNITION DEVICES §18

of the vibrator head, or armature, from the core, and one
for the pressure of the contact points. As there are so
many varieties of coil, an exact rule for their adjustment
can hardly be laid down; but it may be said in g-eneral that
the armature should be as close to the core of the coil as is
consistent with clearance to insure that it cannot touch the
latter. The sprin^^ should be stiflE enough to insure rapid
vibration, but not so stiflE that a considerable current is
required to attract the armature; and the contact screw
should bear with a light pressure, to permit the use of a
small current, but not so lightly as to make the vibrator slug-
gish. The faster the vibrator works and the smaller the
interval between sparks, the smaller will be the angle
through which the engine crank will turn in that interval,
and the more uniform will be the spark time from one cycle
to the next.

The best procedure in adjusting is, first, to run the contact
screw back until it is out of contact; then, to adjust the
spring until the armature is from ^ to /y inch from the core
— the lighter and more rapid it is, the closer it can be
adjusted — and, finally, to run down the contact screw until
a clear and high, but not a tinny, note is produced when the
circuit is closed. Then connect an ammeter in the priman'
circuit, and note the reading when the engine is standing
still and the vibrator working. It should read from .25 to .5
ampere, for a moderate-compression motor; but, if the com-
pression is high, from .5 to 1 ampere may be required. By
adjusting the spring slightly, the current can be reduced
without making the vibrator work slower. When the mini-
mum current has been found, note whether the engine
develops its full power when it is running. If not, try turn-
ing the contact screw down a little more; but do not leave
it down unless it improves the power, as it simply w^astes
current.

40. If the cnpfin** has more than one cylinder, tune the
vibrators separately and as nearly alike as possible. When
a coil is supplied with the engine, it is well to note its

§18 ELECTRIC IGNITION DEVICES 31

sound and adjustment when the engine is received from the
factory, and to restore this sound as nearly as possible when
the coil requires attention.

A weak battery will need a vibrator adjustment different
from that for a fresh battery, the contact screw bearing
with a lighter pressure and the vibrator speed being neces-
sarily somewhat slower.

Occasionally, it will happen that the insulation of the sec-
ondary winding on the coil will break down, which will
cause the coil to give a weak spark or none at all, even if
the battery is fresh and the vibrator adjustment good.
Sometimes, also, the wires leading to the condenser break.
This results in excessive sparking at the vibrator and
timer.

SPABK PliUGS

TYPES OF PliUGS

4t\. The chief difficulty experienced in connection with
the jump-spark system of ignition is found in maintaining
proper insulation of the secondary circuit. On account of
the carbon gradually deposited over the interior of the com-
bustion chamber from the fuel and the slowly-burning cyl-
inder oil, it follows that the most difficult place in the
secondary circuit to keep properly insulated is the point
where the spark is produced. The problem of insulation
here Jias been solved by the use of the spark plugr, a sec-
tion of a representative type of which is shown in Fig. 17 (of).
A spark plug consists of a steel shell a that screws into a
threaded hole in the wall of the combustion chamber; a por-
celain or mica insulator by and a threaded bushing r, by the
aid of which, with suitable packings d^ the porcelain is
made air-tight in the shell ; and a metal stem r, made air-
tight by packing or cement, according to its form. The
seconda\y current is conveyed from the positive terminal of
rhe coil to the binding post /", at the end of the stem e by an

g 18 ELECTRIC IGNITION DEVICES 33

insulated cable, and the spark jumps from ^ to a projecting
point g connected to the shell a. From the shell, the sec-
ondary current goes through the engine frame back to the
negative terminal of the secondary winding, which, like the
battery, is groimded on the engine. By detaching the cable
from fy the plug may quickly be unscrewed for inspection
and cleaning of the porcelain.

The construction of the plugs shown in Fig. 17 (^), (r),
{//), (r), and (/) is but little different from that shown
in (tf). What is known as a closed-end plug is shown in (^),
the points a and b being located in the nearly closed end of
the plug. The point a is concentric with the plug-end
opening into which the point b projects from one side.
The so-called open type of the same plug is shown in (r),
the point a projecting beyond the end of the plug, as shown.
The point b can be turned away from a to increase the gap
between the points. In the plug (</) the point a is mounted
in the hexagonal head b of the insulated bolt c for conduct-
ing the current and for keeping the plug tight, the spark
bridging the gap between the point a and the threaded
shank.of the plug. In the plug (r), the insulated electrode a
resembles a star. The spark occurs between the projections
of the insulated electrode a and the threads of the grounded
electrode b. In the plug (/), the insulated electrode is
threaded and the opening b of the grounded electrode is star
shaped. In the plug (^), the insulated electrode a is
wrapped with sheet mica ^, and then surrounded with mica
washers c pressed closely together under heavy pressure and
held in place by a brass nut d and washer. The groimded
electrode e is fastened in the bushing /. Spark plugs are
sometimes protected against the short-circuiting effect of
moisture by means of a porcelain hood or cap a. Fig. 17
(A), having a recessed neck b on one side to receive the
wire r, which is connected to the plug by a terminal link d
in the manner shown.

43. While there are a great variety of spark plugs on the
market, each with some special features of advant^e that

M»— 7

34 ELECTRIC IGNITION DEVICES g 18

may or may not be possessed by others, the chief require-
ments of a good spark plug are the following:

1. The insulating material of porcelain or mica between
the central electrode or stem, which is connected to the pos-
itive terminal of the coil, must not be too easily coated with
carbon deposit, where exposed to burning gas and oil
vapors. It is to be remembered that the electrical resist-
ance of any gas increases considerably ^ the gas is com-
pressed, so that, although the current may jump between
the proper spark points when the plug is in the open air, it
may find the resistance between these points too great when
the plug is in the cylinder and the charge is compressed,
and will take an easier path through the carbon coating on
the porcelain. Practically the same thing will invariably
happen if the porcelain is cracked, for the same reason,
namely, that the current will take the direct route through
the crack rather than the difficult route from spark point to
spark point through the compressed gas. The leakage
through the carbon deposit is made as difficult as possible
by giving the leaking current a considerable distance to
travel, and there are also special devices sometimes
employed to prevent the collection of carbon.

2. The plug must be easily cleaned of whatever carbon
maybe deposited on it. To clean the plug properly, it must
be taken apart, and it must not be too difficult to reas-
semble the parts and make the plug gas-tight, nor must the
packing process endanger the porcelain more than
necessary.

3. The plug must fit the standard sizes of threaded
spark-plug holes, and must not be unduly expensive t
replace. Among the sizes most used is the so-called metri
size, the proportions of which are based on the metric sys
tern of measurement. Most of the imported spark plugs
are of this size, which is approximately the size of a -J-inc
pipe tap, but is not tapered. American spark plug^ ar
either of the ?r-inch or tlie f-ineh pipe sizes. The pi
sizes are tapered, and depend for ti^ditness on the plu
being screwed in ti.t;lilly. This method is not altogethe

g 18 ELECTRIC IGNITION DEVICES 35

satisfactory, as the thread in the engine wears and permits
leakage, which causes the plug to heat; and both the engine
and plug tapers are liable to variations that may make one
plug screw well into its hole while another catches only a few
threads, and consequently is not so well placed for prompt
communication of flame to the compressed charge. Plugs
that are not provided with tapered threads are made gas-
tight by gaskets of asbestos covered with thin copper
sheathing.

43. It is desirable, though not essential, that the spark
points should be of platinum, since when made of this metal
they do not bum away to any appreciable extent. When
not made of platinum, they are often made of a special alloy
of steel and nickel, which resists oxidation nearly as well as
platinum. The air gap between the spark-plug points should
not exceed -^ inch, nor be less than -^j inch ; the best size is
about midway between these dimensions. In case a battery
gives out and there is no other at hand, the car may be kept
going for a short distance by pinching the spark-plug points
a little closer together, to reduce the resistance offered by
the gap.

AUXILIARY SPARK GAP

44. A plug whose porcelain is slightly covered with soot
can be kept in action by the use of an auxiliary spark-g^ap
device, two forms of which are shown in Fig. 18 {a) and (d).
This device consists simply of two insulated terminals a and d
with points separated by an adjustable gap, usually about one-
sixteenth inch in length. In the form shown in Fig. 18 (a).
the terminals are enclosed in a glass tube c to prevent possi-
ble ignition of stray gasoline vapor. This form is connected
in the secondary circuit by means of the connecting screws
d and t. The form shown in Fig. 1 8 (d) is attached to the
binding post of the spark plug itself, and the spark jumps
from the point a to the binding post d. The base /is made
of fiber.

When the primary circuit is broken by the timer, it

3e ELECTRIC IGNITION DEVICES § 18

requires a short time for the induced current in the second-
ary circuit to build up to its full voltage; and, in order that
the full voltage may be reached, it is necessary that the first
small quantity of energy induced in the secondary shall not
be allowed to escape. If the spark-plug insulation is not
perfect, or if the plug is sooted, the charge first induced
leaks away either through the insulation or over the soot
deposit, and the voltage does not become great enough to
force the current across the gap and produce a spark. By
the use of an auxiliary spark gap outside the cylinder, the

Pig. 18

secondary circuit is held open, this leakage is prevented, and
the induced current builds up to its proper voltage, so that,
when the gap is finally bridged, the entire energy of the
induced charge is employed in producing the spark. With
the recent improvements in plugs, and by proper attention
lo the carbureter adjustment and to lubrication, sooting of
plugs is avoided to a greater extent than it used to be, but
there are many occasions when the auxiliary spark gap is
exceedingly useful.

§ 18 ELECTRIC IGNITION DEVICES 37

TIMERS AND M8TRIBUTOR8

CONSTBUCnON AND OPERATION

45. Timers^ or primary commutators, as they are

commonly called, are devices whose object it is to close the

igrnition circuit at some prearranged point or points in the

TCATolution of the crank-shaft, keeping it closed sufficiently

long to insure ignition, and then opening it, no matter

whether the engine is of the single or the multi-cylinder

typ>e. The principle of operation of all timers is practically

th.o same, but the length of the time of contact varies, and

in. some cases an extremely short life of the battery is the

result. Some timers, especially those on cheap two-stroke

niarine engines, are arranged on the engine crank-shaft,

miprotected by a cover, with nothing whatever to prevent

^^y gasoline vapor in the lower part of the boat from taking

fif^, as there is always a spark or small arc at the time of

breaking the contact.

46. It might be supposed that a multi-Cylinder engine

would be regularly equipped with a single spark coil, whose

primary circuit would be closed as many times in each cycle

of the engine as there were cylinders to be sparked, and

wliose secondary current would be led by a commutating

device to the cylinder desired. This is, in fact, done in some

Tecent cases; but the difficulty found until lately in confining

^e high-tension secondary has led the majority of builders

to prefer commutating the primary, and using a separate

spark coil for each cylinder.

47. In Fig. 19 is shown one form of timer, partly in
section, and Fig. 20 shows it wired for connection to the
^^gine. The case consists of a large fiber disk a, with a thick
raised rim ^, in which are embedded four brass contact pieces r,
^ch connected to its proper coil. The shaft runs through
^e disk a, which has a bearing on the shaft, and carries a

:f8 ELECTRIC IGNITION DEVICES gU

hub d and pivoted lever e, on one end of which is a roller /
that runs against the internal rin^ b and makes contact with
the insulated segments c. A spring g connected to the
other end insures good contact. A rod ctmnecting the arm k
with a lever provided for the purpose of advancing' the sparV
and called the spark advance lever, holds the disk a from
rotaMng with the shaft and determines its position. This

sort of timer is arranged to be oiled freely, and the oil does
not interterc with its working. The arrangement shown in
Fig. 20 includes a button a on the steering wheel of an auto-
nmbile. by which the currentmaybetemporarilyintermpted
at the will of the operator. This is sometimes convenient
when coasting, or in managing the machine when surrounded
by other vehicles. Two pair of storage cellsin their cases are
represented by * and c. Current from the storage batteries
pjissfs to the prim;ir\- windings of the coils in the coil box d,
iIk- tiirri.-iit inihiccd in the SL'Condary windings of^the coils
passing lu fat-h of the spark plugs in turn when the proper
L-ontact at the linicr is made.

48, Because of the arrangement of the cranks, and in
order tn take advanta:.,^e of the alternate movements of the
pistons, iIk- onltT <ir cxploslotts in the several cylinders

; 18

ELECTRIC IGNITION DEVICES

must be either 1-2-4-3 or 1-3—1-2, these numbers correspond-
ing- to the numbering of the cylinders as shown in Fig. 30,
where the order of firing is 1-3— i-3. If the purchaser of an
automobile or motor boat is not sure as to the order of firing of
his engine, he can easily determine what it is by turning the

engine slowly and watching the order in which the exhaust
"Iv-es open, which will indicate the order in which the
charges in the cylinders must be ignited.

^9, That the order of firing must be as just indicated
will be apparent by referring to Fig. 21, which is a diagram-
niatic illustration of a vertical four-cylinder four-cycle engine
sbo\jving the relative positions of the pistons. The arrange-
'"&nt of the crank-shaft is such that, while the pistons in cyl-
inders 1 and 1 are descending on their working and suction
proles, respectively, the pistons in cylinders 2 and 3 are
"loving upwards on their compression and exhaust strokes.
™ptesenting the working, fxhaust, suction, and compression

40 ELECTRIC IGNITION DEVICES § 18

strokes necessary to complete a cycle by the letters IV, £, S,
and C, the following diagrams. Fig, 22 (a) and (it) serve to illus-
tratehow the movement of the exhaust valves makes it possible
to determine the order of firing, which is dependent on the
operative relations between cylinders 3 and 3; that is to say,
whether the compression orthe exhaust stroke is to take place
in cylinder No. 2 or in
cylinder No. 3 when
the order of events in
cylinders No. 1 and
No. i are as indicated.
At the top of the dia-
grams, Fig. 22 (a) and
{d) the aumbers of the
cylinders correspond-
ing to flie numbering
io Fig. , 31 are given,
the arrows just below
the numbers indicating
the initial direction of
movement of the pistons; while the figures at the left indi-
cate the number of degrees of travel of the cranks necessary
to carry the pistons to the beginning of the strokes repre-

0= W C E S

G° W E C S

180° E \V S C iRO' E S W C

3flu^ .-^ y; C W 3,;()° s C E W

U\)' C S W E .540" C W S E

',-i^f W C E S 720= w E C S

si'iitiii liv tilt- luttcrs ]]\ E, S, and C, the beginning of the
working strnkf. or poiiu ;ii which the charge is fired in
cyliuder jVo. 1, lK.-in;f t;ikL-ii as zero.

§ 18 ELECTRIC IGNITION DEVICES 41

50. To complete a cycle in any one cylinder, the crank
must travel 720°, or two revolutions; but, since there are
four cylinders, the crank-shaft receives four power impulses
during two revolutions, and hence, in order that the appli-
cation of power may be uniform, the impulses must occur
180® apart. Fig. 22 {a) shows that, when the working stroke
in cylinder No. 2 begins at 180°, it will be necessary to fire the
charge in cylinder No. 4 at 360°, following with cylinder
No. 3 at 640°, the cycle being completed just at the point
where an explosion is about to take place in cylinder No. 1 at
720**, or two complete revolutions. With this arrangement,
the order of firing is shown to be 1-2-4-3. Fig. 22 (^), how-
ever, shows that, when the second power impulse takes
place at 180° in cylinder No. 3, the order of firing must be
1-3-4-2.

Si, Timers should be oiled and cleaned regularly, but
^yond this they require little attention. Like any other
part subject to friction and sparking, the timer will gradu-
^ly Vear out and will require such attention and repair as
Its Condition and construction may make necessary.

DISTRIBUTORS

It was once thought impossible to insulate the sec-
ondary circuits of a jump-spark system so thoroughly that a
^^n&le coil could be used to advantage for a multiple cylinder
^^^ne, in connection with a secondary commutator or
distributor, to deliver current to more than one sparkplug,
^tely, however, this has been accomplished successfully,
^e method being illustrated in Fig. 23, which is a diagram-
matic view showing the arrangement of the wiring for a four-
^y^inder engine. From the battery a, the current passes
through the switch ^and the primary winding of the induc-
tion or spark coil r to a binding post d connected with the
iiisulated contact member of the timer e. On the cam-shaft,
or any other convenient shaft that turns at one-half the
speed of the engine, is a f our-lobed cam / that makes contact

ELECTRIC IGNITION DEVICES

with the insulated member four times in each revo;
the primary current being completed through the unins
cam /, engine, frame, and ground connection at g.

The spark coil generally has the usual vibrator, but
times the single spark produced by breaking the cin
the timer is considered sufficient. The induced cur
led from the positive terminal h of the secondary coi]

^mmn,

Fig. a

heavily insulated cable /, to an insulated revolving
whose end piisses over four insulated segments or
heads/', k^ connected to the spark plugs as showTi.
army may or may not actually touch the points k^ k^
it dcx?s not, the spark will readily jump the gap if the
is small. The whole is suitablv encased to e:
moisture. The impi^rtant |X»int in a successful distrib
to have ver\- vr^xxi insulation. Hard rubber is the insu
material common Iv used, and all electricallv active
j>arts arc placed as ♦ar aiw:*: :.s nossible.

g 18

ELECTRIC IGNITION DEVICES

53. Commonly, the distributor is mounted on the same
shaft as the timer. Fig, 24 shows this arrangement in sec-
lion and elevation. The primary contact is made by a steel
"ball a, held in place by a spring as shown. The sleeve b and
contact cam c are carried on a shaft turning at one-half the
speed of the engine. The secondary current is led to the
binding post (/, through which
it travels by way of the con-
tact ball e to the brass strip/
that runs over the hard-rub-
ber surface g, and makesi
contact with the flat-headed
screws h, h embedded therein.
These screws carry the cui-
rent to the several spark
plugs. Efficient insulation
between the primary and the
secondary is secured by the
long, hard-rubber stem ( on
which /is carried. The cas-
ing/* is rotated for advance
or retardation of the spark
by the arm k. It is evident
that the movement of this
arm advances or retards both
primary and secondary con-
tacts aUkc. A ball bearing /
is shown, which is sufficient
to support /, as the latter
carries little weight.

54. Ill the combined timer and distributor shown in
Fig. 25, the .shaft a carries at its extreme end the timer
cam b, which has as many lobes as there are spark plugs t«
be supplied. These lobes successively make contact with
the steel plunger e. This plunger is supported in a hard-
rtibber casing rf, and by meansof asleeveisfastened on fl for
rotation according to the spark advance recjuiix^d. Attached

ELECTRIC IGNITION DEVICES

to fz by a taper pin is a hard-rubber barrel c, carrying a
tact ring/ extending clear around it and connected thn
a longitudinal strip with a single contact segment neai
left-band end of e. The secondary current is carried tc
ring/by the contact plunger^, and four other phit
mounted in d make contact successi^-cly with the aegi
connected wtth/i The hard-rubber moantin^ affoids
cient insulation. To the right-hand end of </ is scr^w

metal ring li, from which projects an arm for rotatH
advance or retard the spark. The light casting i alFoi
bearing for the shaft and for /;, and can be screwed to
convenient support, the shaft a being ojjerated by a chfli
flexible shaft driven from the cam-shaft. A glass fro
tlirough which the action of the timingcam maybe watc
is provided.

§ 18 ELECTRIC IGNITION DEVICES 45

IGNITION GENERATORS AND MAGNETOS

GENERATORS

66. Owing to the fact that the ignition circuit of a four-
cylinder engine is closed twice in each revolution, there is a
gfreat consumption of battery power; and, in order to escape
the annoyances of frequent recharging of storage batteries
or replacement of primary cells, various forms of mechan-
ically operated current generators are often employed. The
simplest of these in some respects is a miniature dynamo,
taking the place of a battery, with little or no change in the
coils and wiring. It is generally used in conjunction with
jump-spark coils, but if employed with primary-spark
apparatus no coil is required, as the self-induction of the
armature furnishes the extra current for ignition. Dyna-
mos for this purpose are commonly of the iron-clad type to
exclude water and protect the field windings, and the arma-
tures have a number of coils so that the generators give a
practically constant current.

66. Generators used for ignition are sometimes
employed for furnishing light and for charging storage bat-
teries, the ignition system being so arranged that the excess
current generated when igniting the charges in the engine
is used in charging the storage batteries, which in turn sup-
ply current for starting the engine or furnish current for a
limited number of small incandescent lights.

The difference between a dynamo and a magneto is that
the dynamo consists of an armature rotated through a field
composed of electromagnets, while in the magneto the field
is a permanent magnet. The magneto can be run in either
direction, while the dynamo as usually constructed for the
purpose can be run in one only, as to run in both directions
would necessitate double sets of brushes.

Low-tension magnetos are used for marine gas-engine
ignition, but only with the make-and-break system, because

4G ELECTRIC IGNITION DEVICES g IS

magnetos, as usually constructed, generate alternating cur-
rent, and the inductance coils commonly employed with the
primary ignition system can be operated only by means of
direct current from a dynamo.

57. Dynamo-electric ignition generators require very
little attention beyond occasional oiling, polishing of the
commutator with a piece of fine sandpaper, and trimming
the brushes. They are, however, rather bulky and quite
heavy, and their efficiency per pound is much below that of
special types of magneto-generators. When the motor is
turned by hand, the speed of the dynamo is commonly too
slow to generate a good spark, and it is necessary to use a
dry or storage battery for starting, and to switch to the
dynamo afterwards. If, as is usually the case, the dynamo
generates a more powerful current than the batter}^ gives,
this arrangement has the slight drawback that the coil
vibrators do not generally work equally well with both cur-
rents, and frequent adjustment is required.

58. It is quite feasible to use the dynamo simply to
charge a storage battery, the current for the coils being
taken from the latter, the speed of the dynamo being just
high enough to make sure that the battery will not dis-
charge through the dynamo against the voltage of the iat-
ter. The positive terminal of the dynamo is then connected
through an automatic switch with the positive of the bat-
tery, and the negatives of the dynamo and battery are con-
nected direet. The rest of Uie ignition circuit is the same
as usual. The switch, which is worked automatically by an
electromagnet in the dynamo circuit, breaks the charging
connection when, through the slowing down or stopping of
the motor, the dynamo speed drops too low to generate the
required voltage for charging. The most suitable dynamo
speed will then be such as to give a voltage on open circuit
of T or S volts for charging a two-cell batiery, and 9 to 10
volts 1'<»r a tliree-eL-11 battery.

51), All iL^nition dynamos have self-exciting field mag-
nets, and from thi^ fat't they liave a tendency to oversensi-

§ 18 ELECTRIC IGNITION DEVICES 4^

tiveness, by which is meant that the current they give is
more dependent than it should be on the speed of the
machine. The reason for this is clear when it is remem-
bered that an increase in speed of the armature not only
increases the voltage of the armature current, but, as part
of this current is used to excite the field magnets, intensifies
the magnetic field also, producing a still further increase in
the intensity of the induced current in the armature. This
is one of the principal reasons for employing a centrifugal
g-Qvemor, by which the speed of the dynamo is prevented
from becoming excessive. Of course, another reason for
the use of a governor is to avoid unnecessary mechanical
wear and tear, which would be considerable with working
speeds in excess of from 1,200 to 1,500 revolutions per min-
ute. Another device that partly remedies the oversensitive-
ness just mentioned is to oversaturate the field coils; or, in
other words, to wind them so that the soft-iron core will be
fully magnetized at a comparatively low armature speed.
From that point, as the armature speed increases, the
increase in intensity of the fields is comparatively small, but
of course the armature voltage is still free to increase in
proportion to the armature speed.

60. An objection to the direct use of the dynamo as a
source of ignition current is that it is liable to give an exces-
sively hot spark that quite rapidly burns away the contact
points of the. tremblers on the coil, and may even endanger
the insulation of the coils themselves. Moreover, the con-
siderable number of coils of fine wire on the armature nec-
essarily involves greater danger of an electrical breakdown
than a smaller number of coils of coarse wire would.

MAGNETOS

Ol. For the foregoing and other reasons, preference is
frequently given to certain forms of magneto-generators
having" permanent field magnets whose intensity is unaf-
fected by the speed of the machine, and which have armatures

48 ELECTRIC IGNITION DEVICES §18

of the simple H type with but a single coil of compara-
tively coarse wire. These magnetos can be made very
light, and the fact that the current induced in the armature
fluctuates from zero to a maximum twice in each revolution
is not a disadvantage, because the armature is always run in
step, or synchronism, with the engine, and the circuit is
broken for the spark when the armature current has its
maximum value. Running in step, or synchronism, means
that the rotations of the armature shaft and of tKe engine
shaft are so timed that the maximum voltage of the current
occurs at the point of the rotation of the engine shaft where
the explosion should occur. By reason of the fact that the
field magnetism is definitely limited and the armature can
turn no faster than the engine, a magneto may be directly
short-circuited on itself without injury, and this fact alone
is of great value in protecting these machines from acci-
dental electrical injury. Magnetos, like dynamos, are used
for both primary and secondary-current ignition.

62. In all continuous-current machines, the current, as
it comes from the armature coils, is commutated at the
brushes so that a direct current is delivered to the circuit
In an ignition magneto, however, the direction of the cur-
rent is of no consequence, and of the two terminals of the
coil one is simply grounded on the armature core, while
the other is led to an insulated collector ring on the shaft,
from which it is taken off by a single brush. This results,
on each alternate reversal of the current, in the grounded
terminal being positive, instead of negative as conventional
practice requires, and to guard against short circuits very
careful insulation is required.

G3, When an H armature is run in step,or synchronism,
with the crank-shaft of a four-cylinder engine, it is only
necessary to interrupt the annature circuit twice in each
revolution at or near the points in the revolution where the
current is the greatest. To insure the current being a maxi-
mum at the moment of ignition, the armature shaft maybe

g 18 ELECTRIC IGNITION DEVICES 49

rotated with reference to the engine shaft when the ignition
time is changed, this being done by the use of a sleeve with
an external spiral groove and an internal straight feather,
which is interposed between the armature shaft and its
pinion. By shifting this sleeve lengthwise, the armature is
rotated through a limited angle in relation to the engine
shaft.

€4. If the induced current is sufficient, it may be unnec-
essary to break the circuit exactly at the point where the
current is greatest, and the sliding sleeve may be dispensed
with. In this case, it is customary to break the circuit with
thie current near its maximum when the engine is running
at its highest speed, in order to give the most rapid inflam-
iriation when it is most needed, and to permit the break to
take place with a lower current when the speed is not so
M^h. Owing to the intensity of the magneto-current, it is
fot-ind that very little advance is required, compared with
w'hat is necessary with a battery current.

C5. liO'w-Tension Magrnetos. — So far, the description
^^ the magneto applies to both the low and the high-tension
typ^es. The low-tension magneto is operated in connection
^'ith a make-and-break primary spark device. When used
^^ automobiles, it is somewhat lighter in construction than

on. stationary engines, owing to the higher speed at which

automobile engines run.

66. A diagrammatic illustration of the armature core
^d pole pieces of a special type of low-tension magneto
ctnployed in connection with make-and-break devices is
shown in Pig. 26. In this magneto, the armature a is sta-
tionary in the position shown, and it is enough smaller than
the pole pieces ^, b to permit a soft-iron screen c to pass
^tween them. The effect of this screen is to divert the
lines of force at each eighth of a revolution, sending them
alternately through the body of the armature core and
through the ends, as shown by the dotted arrows. Since
this reverses the current four times in each revolution,

168—8

fiO ELECTRIC IGNITION DEVICES g 18

instead of twice, as is the case with the ordinary rotating
armature, it will be evident that the induced voltage is
much higher, mak-
ing it possible to
build this magneto
so as to be very light
in proportion to its
output.

67. Anotherlow-
tension magneto is
shown in cross-sec-
tion and longitudinal
section in Fig, 3T.
It is driven by gea*^-
ing at the speed oi
'^'°- " the engine, the gea.-rs

being set so that the range of the spark timer coincides witli
tile effective range of the magneto-current. The armatu *^
pt>sitions determining the latter are marked on the magnet*''
iiiiii it is unnecessary' to change the angular relation of tftr3<

7iS

v.jnnc cr.ink-sh.ift when the spark isadvanced
-.0 i->r!:'.C!i\i; fcii-^rt-s of coostruction are as

ELECTRIC IGNITION DEVICES

The permanent mag^oets a have cast-iron pole pieces b
fastened to them by screws. The cast-iron armature core c
is wound with double silk-covered magneto-wire, and the
ends of the core are screwed to hard brass disks d, into
which the two shaft sections c, e are screwed and riveted.
The object of this construction is to make a neater and more
II compact winding of the armature than would be possible if
ll the shaft passed right through the core. One of the ter-

I minals is insulated, while the other is grounded on the

II frame of the generator. The insulated terminal of the coil
is connected to a hardened-steel boIt_/i insulated by a mica

II bushing jf through the armature shaft, and the current is

taken off by a hardened- steel contact pin h in the brass

|l mounting /. carried by the hard rubber tube j screwed over

ll the end of the bearing. From t, a flexible connector leads

I to the binding post k. The entire magneto is provided with

IIbii aluminum housing comprising a sheet cover /, and cast end

|l plates m and «, together with top and bottom yokes o and/,

ij and a cap ^ to exclude dust. The shaft is oiled by oilers r, r.

\ The magneto is used without a spark coil, the binding post k

being connected to the insulated electrode of a make-and-

break igniter. The extra current required to give a large

spark is supplied by the self-induction of the armature.

68. HlKh-Tension Magnetos. — High-tension magnetos
maybe divided into two general classes: those that simply
talte the place of the battery and timer and deliver current
to an induction coil of the ordinary construction, in which
tile secondary current is induced; and those that comprise
"> their construction all the elements of generator, timer,
lid induction coil. One of the former type is shown in dif-
ferent views in Figs. 38 and 39. The generator portion of

Ihis

magneto is substantially the same as that of the low-

IfDsion magneto shown in Fig. 27. The current is collected
from the insulated bolt a in the armature shaft by means of
a small bronze bearing b, provided with an oiler, and bear-
'ig against a stationary pin to prevent it from rotating,
. Jlie other end of the armature shaft carries the timer or

§ 18 ELECTRIC IGNITION DEVICES 63

interrupter, which has a two-lobed steel cam c that works
against a rocking arm d pivoted at its center. Contact is
made between the screw e and a spring carried by the rock-
ing arm d, and when the latter is tripped by the cam the
upper end of the arm strikes the spring a blow that effects a
quick separation of the contact points. The current is
taken from the collector b to the spark coil and from the
spark coil it passes through the rubber bushing /to the insu-
lated contact screw e, and then through the frame of the
magneto to the grounded terminal of the armature winding.
The spark time is changed by rocking the housing g of the
timer on its axis. This at the same time changes the point
of maximum current in the armatiu-e winding in the follow-
ing manner:

The armature is surrounded by two soft-iron sectors A, //,
Fig. 28, forming magnetic bridges somewhat similar to the
screen of the magneto shown in Fig. 20. These are car-
ried on brass end plates /, /, Fig. 29, secured to hubs that
furnish bearings for the armature shafts. These hubs are
supported in the end plates of the aluminum housing, and
one of them has the timer housing fastened to it at its
outer end. Consequently, the sectors k, h are rocked with
the timer, and in this manner the direction of the magnetic
lines through the armature is changed. The effect is the
same as if the pole pieces themselves were rocked to change
the point of maximum induction.

69. The armature runs at the same speed as the engine,
and delivers two sparks per revolution, one for each cylinder
in turn. The spark coil is not provided with a trembler,
only a single spark being produced at each rupture of the
circuit by the timer. The positive terminal of the second-
ary winding of the coil is carried by an insulated cable,
through the top of the hard-rubber housing at the left end
of the magneto, to a binding post connected to the flat
springy. From this spring the current goes to the revolv-
ing distributor arm k^ and is taken off by four insulated
contact pins connected to the several spark plugs. The

54 ELECTRIC IGNITION DEVICES § 18

hard-rubber rod / carrying k is supported and rotated by the
shaft ffty which is driven by the gear n and pinion o at one-
half the speed of the armature shaft. The oilers p keep the
shaft lubricated, and the centrifugal oil flange q prevents
any surplus oil from reaching the hard rubber,

70. The high-tension magneto just described, although
very simple, does not attain the highest efl&ciency possible
in apparatus of this type. It is apparent that in this class
of magneto the extra current self -induced in the armature
winding or the primary coil, which is utilized to give the
spark in the primary ignition system, is objectionable
because it prevents the instantaneous cessation of magnet-
ism essential to the inducing of an energetic current in the
secondary winding, exactly as when a battery is employed
with a jump-spark coil. This momentary extra current is
therefore absorbed by a condenser, and got rid of as far as
possible. So far as it cannot be got rid of, it manifests
itself by burning the contact points of the trembler and the
timer, necessitating occasional cleaning or renewal.

71, In Fig. 30, suppose that a is the armature wnnding;
b^ the timing cam (arranged in this case for a single-cylinder

Fig. 80

engine) ; and c, the contact maker, the lever d being* sup-
posed to be pivoted at its center, as in the timer shown in
Fig. 29. The circuit is completed from the timer to the
negative terminal of the armature coil through the engine
frame, represented by the dotted line e. Suppose an induc-
tion coil of the familiar sort to have a primary winding /,
and grounded return connection g^ whose switch h is nor-
mally closed. The secondary circuit is not shown. Fur-
thermore, suppose that the primary winding is of moderately

§ 18 ELECTRIC IGNITION DEVICES 65

high resistance, and that the contacts of the timer are nor-
mally closed, thus short-circuiting the armature on itself
except at the moment of rupture, when it is desired to pro-
duce a spark. As was just explained, a magneto can be
short-circuited without injury; but the current in the arma-
ture and coil will be high. If, now, the contact at c is
broken when the current is at its maximum intensity, the
result is not a complete breaking of the return path for the
current, since the path through f-g-h is still open. Never-
theless, the resistance of this path is considerably greater
than the direct path through c-d-e. Considerable extra
current will be induced and will necessarily travel through /.
By this arrangement, it is seen that the momentary extra
current, which is much more energetic than the regular
current generated by «, even when the latter is short-cir-
cuited, owing to the large current generated by the mag-
neto on short circuit, is usefully applied to induce the
secondary current in the spark coil.

72. The location of the switch h shown in Fig. 30,
although somewhat common, is incorrect, since if it is left
open it entirely deprives the armature of a path for the
extra current, and produces excessive sparking at the
contact points r, where there ought to be no sparking at all.
This is correfcted by arranging the circuit as shown in
Figf. 31, in which the switch is so located as to short-circuit

Pio. 8t

the coil /"when closed. With this arrangement, the switch
is opened when it is desired to use the toil, and is closed to
stop the current, which is the reverse of the usual arrange-
ment. Its effect is simply to let a run short-circuited as
long as the switch is closed.

£6

ELECTRIC IGNITION DEVICES

73, Another ma^eto, the arrangement of which is
shown in diagrammatic form in Fig. 3%, does not depepd on the
momentary extra current, and differs from others in that no
induction coil is used, the armature core itself serving the

purpose of a coil. The heavy line a indicates the primary
winding on the armature core. Rupture is produced by a
timing cam 6, while a condenser c absorbs the extra current
on rupture. The armature, however, is provided with a
secondary winding d, in which the current for the spark
plug e is induced. This system has the advantage of
simplicity.

74, A very ingenious high-tension magneto, sectional
and end views of which are shown in Fig. 33, depends

neither on simple Rupture of the primary nor on directly

utilizing the momentary extra current. Instead, the pr«
marj' current is used simply to charge a condenser, and th<
spark is induced in the secondary winding by the dJschaig*

Il«

ELECTRIC IGNITION DEVICES

of this condenser through the primary winding of an induc-
tion coil. Thus, the contact make-and -break by which the
condenser is charged does not need to have its timing
ctianged, the only change in time being that connected with
ih^ condenser discharge. The coil is equipped with a
vibrator, but the vibrator itself is employed only in start-
ing, for which a battery is used, and is inoperative when the
cuirent is supplied by the magneto.

"75. The armature is of the H type with laminated core
<z, and runs in ball bearings. On the armature shaft is
nnounted the regular
primary interrupter b,
having a circular cam
with two lobes, thus
inaking and breaking
the circuit once for each
stroke of the engine,
which is here supposed
to have four cylinders.
" second shaft c is run ;
''? the pinion and gear
^ and / at one-half the
*Pfied of the armature,
Md carries a four-lobed
P"rnary contact maker
/and also the secondary
swrent distributor g.
Pie- 34 shows the wir-
'"ff connections. One
™d of the armature
Ending is grounded on
the Qore, as usual, and

fte other is connected

t" the interrupter b, and

through the wire h to the primary of the induction coil j.

The other terminal of the primary is connected to the coil
vibrator and also to the condenser j. A switch k has its

58 ELECTRIC IGNITION DEVICES § 18

blade connected with the other condenser terminal, and has
the three contacts connected, respectively, to the vibrator /
and the positive and negative terminals of the battery f«, as
shown. The positive terminal of the battery is g^rounded.

7 6. When the switch is in the position shown by the dotted
lines, and the circuit is closed by the primary interrupter i,
a charge of electricity passes through the wire A and pri-
mary winding of the coil / into the condensery. As soon as
the condenser is charged, which takes but an instant, no
further current can flow, as there is no return to the
grounded terminal of the armature. The circuit is then
broken, leaving the condenser charged, and at the proper
moment for the spark a contact is made by the timer /", thus
grounding the wire A and permitting the condenser to dis-
charge itself through the primary winding of the coil i, the
flow being now in the opposite direction to that of the
momentary charging current. The discharge of the con-
denser is so sudden as to induce a very high momentary volt-
age in the secondary winding of the coil.

77. As one end of the secondary winding is connected
to the primary winding, the secondary winding is grounded
while the timer /is making contact. The other end of the
secondary winding is connected by the cable n to the central
terminals of the high-tension distributor^, whose arm/,
Fig. 33, is secured to the rotating hard-rubber disk g
attached to the shaft c. Four fixed terminals, mounted in
the same hard-rubber piece r that holds the central ter-
minal, distribute the current to the spark plugs. As the end
of the arm p is widened, no advance is required in the dis-
tributor, and hence the timer/, Fig. 34, is the only member
moved to change the spark time, the condenser simply
remaining charged, between the moments of contact, by b
and/, respectively.

As already slated, tlie battery furnishes current for start-
ing, the switch /(' then being turned to the position shown
in full lines in the diagram. The magneto is thereby dis-
connected, and the battery current goes through the engine

§ 18 ELECTRIC IGNITION DEVICES 59

frame, contact maker y, wire A, primary winding of the coil,
VT^brator ^ and the switch. The current can also go by way of
tlie armature winding and interrupter b ; but, if the vibrator is
adjusted for the current reaching the coil by the more direct
route, it will not respond to the weaker current When the
engine reaches normal speed, the switch is thrown over by
the operator. The switch is of special design, and is very
highly insulated to protect the operator from shocks. It is
claimed that this magneto will produce a 3-inch spark in the
^pcnair at 600 revolutions per minute, and a f-inch spark at
50 revolutions per minute. As but a single spark is pro-
dxiced, it can be timed with perfect accuracy.

CARE OF DYNAMOS AND MAGNETOS

78t A magneto or djmamo requires little care except to

*^« that it is mechanically in good order. The bearings

sliculd be oiled at proper intervals, and the commutator

touched now and then with an oily rag. The brushes

should be watched to see that they bear evenly and with

sufficient pressure to prevent sparking. Copper or carbon

^ust from the commutator will gradually collect on the wires

leading to the commutator, if these are exposed. So long

^ it does not short-circuit the wires it does no harm, but it

should be brushed off now and then.

The distributor of a high-tension magneto is likely to pro-
duce metal dust from the rubbing of the contact points, and
^heu this lodges on the hard-rubber mounting it will in
tinie lead to a short circuit from one high-tension terminal to
^enext. It should be wiped off frequently with a slightly
oily rag, and the film of oil left will serve the further pur-
pose of preventing moisture from forming on the hard rub-
^r, which would be as bad as the dust. On account of the
%h secondary tension, great care is necessary to maintain
Perfect insulation.

'?9. All switches of magnetos should be heavily insu-
lted. K necessary, a rubber tube may be slipped over the

60 ELECTRIC IGNITION DEVICES §18

switch handle. As the current is very strong-, the shocks
that might be recei\-ed by careless handling would be most
violent. With magnetos of the type shown in Fig. 20, a
secondary wire should not be disconnected and left where
no spark can jump when the engine is running. This
would put a severe stress on the insulation, which might
ultimately break down. This is a good rule to follow with
all jump-spark systems, both magneto and battery.

Some high-tension magnetos work best with a smaller
spark gap than is used with primary battery ignition, it
being about one-half the length used with a primary battery.
In the absence of instructions from the maker, the length of
spark is best determined by trial.

SWITCHES

80. Knife switches such as are shown in Fig. 35 (a), {b),
and (c), are commonly used in marine and stationary prac-
tice. While the copper or brass used in them is liable to
oxidation, they give the best service on motor boats because
the action of opening and closing them tends to keep the
contacts bright. The single-pole knife switch. Fig. 35 (a),
has a detachable knife lever (7 that may be carried in one's
pocket to prevent unauthorized use of the boat or automo-
bile. There are three contact points *, r, and d. When the
knife a is thrown in at *, connection is made with orue set of
batteries, and with another set when thrown in at rfl When
both batteries have been weakened through use, the blade
may be thrown in at r, connecting the batteries in parallel
scries and thus increasing the strength of the current deliv-
ircd. What is known as a double-pole single-thnnv knift
S7i'//i'/i is shown in Fig. 35 (d) ; while a switch of the same
type but having a double throw is illustrated in Fig. 35 (c).
Wires from two sets of cells or other sources of electric cur-
rent arc connected to the poles of the switch beneath the
])ase pL'itc, one set of wires leading to the poles a and ^, the
other set leading- to the proles c and {l, connection with the

ELECTRIC IGNITION DEVICES

external circuit being made through the posts e and f, in
which the knife blades are pivoted.

^1. Fig. 36 ia) and {b) shows the external appearance
*''*1 system of wiring of a switch for use on automobiles
'"" motor boats having single-cylinder or multi-cylinder
^Sines, and with one oi' more sources of current. Thecon-
^^t points of the switch, as shown in Fig. 36 {a), are
*^anged so that, when the switch arm, or lever, attached
'•* the post a rests on the button b, no current flows. When
""f. one set of batteries is in use; when on d, the second
Lti&iniise; when one, the batteries are connected up in

ELECTRIC IGNITION DEVICES §18

multiple series, increasing their ampere capacity; and when
on/, the batteries are connected up in series, increasing flw
voltage. Fig. 36 {6) shows the switch wired for use witli
two sets of dry-cell batteries A and Ji supplying current for
the primary circuit of
the spark coils C, from
which the wires of the
secondary circuit lead
to the spark- plugs D of
a four-cylinder engine.
The binding screw a,
Fig. 36 (i), for the .
switch-arm post a. Fig.
36 (a), is wired to the
primary terminals of the
coils C. From the car-
bon plate of the right-
hand end cell of battery

^^PT

A. a wire is carried to the binding screw c , tlie wire from the
carbon plate of the right-hand end cell of battery B bdng
carried to the binding screw f, under which is a link or con-
tact strip s connecting »nth the contact points t/ and /
Thus far, the some letters of reference apply to similar paitl
in Fig. 36 {a) and (A). A wire from the zinc of battery A is
connected to the bindingscrew^ attached to the metal plate il^

i 18

ELECTRIC IGNITION DEVICES

A wire from the zinc of battery B is connected to the bind-
ing screw i attached to the metal plate/. In a fiber plate k
fixed on the post a, Fig. 3fi [n), so as to turn with it when
the switch arm is shifted, are motmted throe contact pins/,
tn, and « that slide on the metal plates // and j. These pins
are electrically connected by means of a wire o laid in a slot
in the fiber plate k and soldered to the pins.

When the end of the switch arm rests on the contact point
c, current flows from battery ,/ to c, thence through the
switch arm toa, thence by wire/ tocoiis C, and by grounded
connections J and r back to battery,'). When the switch
arm is on d, current flows from battery B to e, thence
through the metal plate s to d, through switch ann to a, to
coils C, to grounds q and r, wire / to binding screw g and
plate h, pin /, wire o, pins m and k, plate J, screw i, and
wire u, back to battery B. When the switch arm rests on e,
it also makes contact with the auxiliary contact point v. Fig.
36 {a), which is connected to c. Fig. 36 {b), by means of the
metal plate w. The two wires from the carbon plates of the
right-hand end cells of the two batteries are thus connected
together, the two wires from the zincs of the left-hand end
cells of the two batteries being connected by means of the
contact pins /, m, and «, wire o, and plates k and j. The
batteries being thus connected up in multiple series, current
Sows through binding screw e and switch arm to a, then to
coils C, grounds y and r to battery vl, and to battery 5, by way
of wire t, binding screw g, plate h, pins /, w, and «, and wire
o, plate J, screw (', and wire a. When the end of the switch
arm is shifted into contact with/, the pin /is moved out of
contact with the plate h, while the pin « makes contact with
the metal plate x, thus connecting the carbon of battery A
to the sine of battery B, and thereby placing the batteries
in series. Current then flows through the wire from the car-
bon plate of the right-hand end cell of battery B to e, then
through plate s to /, through switch arm to a, to coils C, to
grounds g and r, back to the left-hand end cell of battery j4,
thus completing the circuit.

To prevent unauthorized use of the automobile or motor

ELECTRIC IGNITION DEVICES

boat on which the switch is used, the contact post a is made
removable.

82, Snap switches, the operative principle of whicJiia
illustrated in Fig. 37, are commonly used for opening and
closing the primary ignition circuit in stationary and maiine
gas-engine practice. Fig. 37 shows a typical single-pole
snap switch; the same type of switch is made double-pole —
also, three-point and four-point. The wires from the bat-,
tery or other source of primary current come through the por-
celain base of the switch, and are held in posts a, b, which

also carry the switch contacts. When the switch is closed,
the rotary cross-piece c makes connection between posts a and
b, thus closing the circuit. A double-pole switch has two
pieces c and four contact posts. It is desirable to have snap
switches provided with an indicating dial, as shown in
Fig. 37 (fl), unless the position of the switch handle shows
clearly whether the switch is "on" or "off,"

83, A switch for use with high-tension currents where
two sources of current are available, as where storage bat-
teries and coils are installed together with a magneto, is
shown in section in Fig. 38. By throwing the switch han-
dler to one side, the magneto- circuit is closed and the magneto

g 18

ELECTRIC IGNITION DEVICES

is in operation; throwing the switch handle to the other
side cuts out the mag-
neto, closes the bat-
tery - and - coil circuit,
and places the batteries
and coils in operation.
The ball contacts If are
lield against the con-
tacts c by the springs tf,
and are in electrical
connection through the
strip e. Wires from the
two sources of current
are led to the binding fki,«

screws y and ^, the common circuit-completinjf wire being
attached at h.

MAXE-AND-BURAJK WIBIKO

, The wiring diagram shown in Fig, 39 illustrates the
metinid of wiring for a two-cylinder engine, the same
scheme being equally applicable
in making connections to multi-
lylinder engines. When contact
between the insulated and uninsu-
lated electrodes of the igniter is
made, current passes from the bat-
tery a through one blade of the
■frj- Y I switch b to the insulated electrode

^ ' of the igniter </, then through the

uninsulated electrode of the igniter
to the grounded connection e, to
the coil c, and back to the battery
through the other blade of the
switch b.
85. Fig. 40 shows the wiring for a generator.or dynamo/,
and one set of batteries. The spark coil c. Figs. 3i) and 40,

ti|«|i|i|i-

ELECTRIC IGNITION DEVICES

§18

is located between the ground on the engine and the switct
The object of this is to provide means for connecting

^^ — =* — vr-

Hiil'H

* I

Fig. 40

another set of batteries, using the same terminals as are used
for the generator/.

86, Fig. 41 shows two of the cylinders of a four-cylinder
engine connected to one set of batteries, and the other two

""%

J «

k»

^ hCHI f HiliiiliH

Fig. 41

connected to a separate set. It should be noted that the bat-
teries are so located as to make it easy to connect the cells
so as to double the amperage when the batteries become
nearly exhausted.

§18

ELECTRIC IGNITION DEVICES

87. Fig. 42 shows a double system of wiring for a four-
cylinder engine with two coils and two sets of batteries.
One coil could be removed by connecting the two points
of the switches that are wired to the coils and placing
one wire of a single coil in connection with the engine

Fig. 42

ground while the other is connected to the wire joining the
two switch points. If both switches should happen to be
closed at the same time, the current from both batteries
would pass through the coil, and the amperage would be
doubled but the voltage would not be increased.

Pig. 48

88. Fig. 43 shows double wiring throughout, for a four-
cylinder engine, with a generator so connected up that either
pair of cylinders may be operated by either of two sets of

C8 ELECTRIC IGNITION DEVICES g 18

batteries a, a, or by a generator y, or all may be operated by
both sets of batteries together, in case they may have become
weak.

In connecting and setting up batteries successfully, it is
only necessary to use a little thought, to reason out the com-
plete circuit, which includes the engine ground, spark coil,
batteries (or generator instead of batteries), switch, and insu-
lated electrode.

JUMP-SPARK WTRING

89. In wiring an engine for jump-spark or high-tension
ignition, there are two general systems: In one system, the
primary, or low-tension, current is commutated or alternately
closed and opened, and in the other a so-called distributor is
employed to close and open the induced, or high-tension,
circuit for each of the cylinders. The object of this second
system is to obviate the use of a separate spark coil for each
cylinder.

The first is the system most in use. The positive or th^
negative poles of the coils should be connected together and^
wired through the switch, battery, and generator or direct —
current magneto to a ground on the engine. If the positive
poles are connected, each positive pole of the secondary wir —
, ing should also be included in this connection, unless ther^
is a connection in the coil itself. Wires should be run fron:^
each binding post on the commutator to its coil. The wir^
should b2 well insulated, and of the same size and quality a^
used in make-and-break ignition. All joints should be made
carefully, to be sure of good contact. The secondary wir-
ing, which carries a current often as high as 30,000 to 40,000
volts, should be specially made for the purpose, to avoid
dangerous and faulty leaks of current. It should be as
short as convenient, should be kept away from metal work
of all kinds as much as possible, including parts of tjie
engine, and should connect the spark plugs with their
respective coils. There is so much more dampness (particu-
larly around salt water) in boats than in automobiles that

§ 18 ELECTRIC IGNITION DEVICES 69

electrical losses due to leakage are more frequent in marine
practice and have to be guarded against constantly,

90. In wiring for high-tension distribution, the primary
circuit is completed from a ground on the engine or uninsu-
lated part of the distributor through the coil and battery,
generator, or direct-current magneto, and to the single insu-
lated binding post on the distributor. The secondary bind-
ing post of the coil is connected to the primary, both being
positive or negative ; and, by means of heavy special secondary
wire, the other secondary pole is connected to the single sec-
ondary binding post on the distributor, while secondary wir-
ing connects each plug with its proper terminal on the dis-
tributor. In connecting the secondary binding post on the
coil, it is necessary to be sure that it is on the side leading to
the engine ground rather than to the insulated electrode on
the distributor.

The wiring of a marine gas engine should be very care-
fully done, particularly if the current is of high tension ; for,
unless the very best material is used, and the work is done
properly, there will be positive danger from explosion or fire.
For this reason, manufacturers generally recommend make-
and-break ignition when the engine is installed in a cabin
or other enclosed space. Fire-insurance rates on such craft
axe high, and risks are hard to place.

IGNITIOX VmiE CABI.E

91. High and low-tension wire cable, such as is com-
monly used on automobiles and motor boats, is shown in
Fig. 44 (a) and {b). The primary, or low- tension, cable is
shown at (a). The wire core of the cable consists of forty
strands of No. 30 tinned copper wire. The insulation con-
sists of one layer of high-grade vulcanized rubber rt:, while the
protective covering consists of two braids c and d covered
with two layers of enameled coating baked on. It would take
about 12,000 volts to puncture this insulation. The core
of the high-tension cable (/^) is the same as that of the

ELECTRIC IGNITION DEVICES

§1*

low-tension cable. The insulation consists of three layers of
rubber «, b, c, vulcanized together. The rubber is protected^
by two braids e and /, covered with four coats of enamels

'PiMi MMMH y///yy/^ / ////// ////// ///a/ ///v^

PIO. 44

baked on in steam-heated ovens. The enamel forms a flexible
insoluble film that protects the rubber from heat, oil, an
water, the braid protecting the cable against mechani
injury. More than 40,000 volts is necessary to puncture th
cable.

AUTOMOBILE AND MARINE
ENGINE AUXILIARIES

TBAIN^SMISSIOK MECHANISM

SPEED-CHANGING SYSTEMS

1. Every automobile driven by an intemal-combiistion
engine is provided with means for changing" the ratio of gear-
ing, and for reversing, between the engine and the point
where the power is used. The power is utilized at the rear
axle, the rear wheels being the driving wheels. The engine,
or driving, shaft and the driven, or propeller, shaft are sepa-
rate, and provision is made between them for changing the
speed and reversing by means of gears called speed-change
gears. The reason for providing such speed-change gears is
that the internal-combustion engine gives its highest effi-
ciency when working with full charges. Consequently, it is
desirable to operate the engine under those conditions as much
of the time as possible, modifying the speed of the automo-
bile by changing the gear ratio to suit the power actually
developed.

Motor boats are generally provided with a reversing
mechanism, having only one forward and one reverse speed.

3, The automobile engine is proportioned and geared
so as to drive the car at maximum speed on a smooth
road when the throttle is fully open. If the road or grade

QtfyriS^tdhy Initmatitmal Textbook Company. Entered at Stationers' Hall^London,

1 19

2 AUTOMOBILE AND MARINE §19

resistance increases, the car necessarily slows down to a
point where the resulting reduction in the resistance of
the air or wind offsets the increase in road or grade
resistance, and if this speed of the car is insufficient for the
engine to run properly the gear ratio must be increased to
enable the engine to carry the load. This simply means
that, while the engine speed is unchanged, the speed of the
car is reduced by the change of gears. Every gasoline auto-
mobile has at least two choices of gear ratios for forward
motion, in addition to a single slow-speed reverse-gear move-
ment. In the higher-powered cars, three and often four
gear changes are -provided, by which means the engine may
always be run at approximately the most advantageous speed
to get the power it is capable of developing. These gear
changes are convenient also when it is desired to run the car
slowly, since even with the best carbureter and the best engine
design, it is impossible to run a gasoline engine effectively
below a certain speed, which is generally between 200 and
400 revolutions per minute. If a lower car speed is desired
it is obtained by using one of the lower speed gears.

There are in common use three systems of speed-changing
gears, commonly known as transmission gears ; namely,
the sliding'gcar system^ the mdividual-clutch systetn^ and the
planetary system,

SLII>IXG-G£AB TRANSMISSION 8T8TEM

3. In Fig. 1 is shown a plan view, with body removed,
of a small touring car equipped with a four-cylinder gaso-
line engine a and sliding-gear transmission b. From the
speed-changing gears the power is transmitted through a
jointed propeller shaft c and bevel pinion and gear, enclosed
at d^ to the rear axle e. Attached to the engine shaft is the
flyi\'heel / carrying a friction clutch, and just back of the
clutch is a coupling g connecting the clutch with the speed-
changing gears. At // is a brake; at/ and/ are universal
joints, which will he described later; and at k and /are hub
brakes. In this transmission system the drive is direct^ as it

AUTOMOBILE AND MARINE

il9

is called, in the high-speed gear. In the slow and interme-
diate gear positions, generally called the first and second
gears, the power is transmitted from a pinion on the engine
shaft to a gear on a lay shaft, or jack-shaft, and from a pinion
on the lay shaft back to a gear on the propeller shaft in line
with the pinion first mentioned.

In Figs. 2, 3, 4, and 5 is shown a sliding-gear system with
three forward speeds and one reverse speed. The coupling
shown at a. Fig 2, connects the short shaft b to the engine

shaft, while the coupling c at the other end connects the
short shaft a' to the propeller shaft The shafts b and d are
separated close to the gear e, which is ke)wd to the shaft b
and has a portion of a coupling on the side toward the gear/
to which is connected the other portion of the coupling.
The gears _/'and g are fastened together by a sleeve that
slides on a feather in the shaft d; it should be noticed that
the gear /is smaller in diameter than the gear ^. The lay
shaft h carries the gears /, /, and k that are keyed to it and
the gear /on a sleeve that slides on a feather. The gear k
is slightly smaller than the gear/', so that, when the gear ^ is
moved to the extrenre right, it does not mesh with k but

} 19 ENGINE AUXILIARIES 5

vith a small idle pinion m that is in mesh with i. A brake
3 shown at n on the shaft d.

4c, In the position shown in Fig. 2, the transmission sys-
lem is set for the slow forward speed of the car; the gear /
s in mesh with the smaller gear e, reducing the speed of the
ihaft A, while the gear / meshes with the larger gear g,
igain reducing the speed so that the shaft d turns slower
than k and much slower than the shaft b.

In Fig. 3 the gears are shown set for the intermediate
forward speed, with the gears e and / still in mesh; but the
gear (', which is larger than the gear J, is in mesh with
the genrf, which is smaller than the gear^. Consequently,
the speed reduction from the shafts to (/is less than in the
case shown in Fig. 2.

I n Fig. 4 the gears are set for the high forward speed. The
gear / has been moved out of mesh with the gear e, and the
sleeve carrying /and ^ has been moved so that the clutch
on /engages with that on gear e and the two shafts h and <f are
locked together and turn as one shaft, there being no gears

AUTOMOBILE AND MARINE

in mesh. The propeller therefore rotates at the same spe^=
as the engine shaft

In Fig. 5 the gears are shown in position for the revere

motion. The gears e and / are again in mesh, bat the gear^
is in its farthest pnsitinn to the right and in mesh with the

§ 19 ENGINE AUXILIARIES 7

idler m that is behind and in mesh with the gear k. Conse-
quently, the shafts b and d turn in opposite directions, and
the propeller shaft runs at the reverse speed, giving a back-
ward motion to the automobile.

To avoid shocks in changing gears, the coupling a^ Fig. 2,
is not connected directly to the motor shaft, but is connected
to one member of a friction clutch partly enclosed in the fly-
wheel, shown at/", Fig. 1, and this clutch is invariably
released before changing gears. In this manner the shock
involved in changing gears is confined to that necessary to alter
the speed of the gears themselves and of the part of the clutch
connected to a. Fig. 2. The gears are made of a special
tough steel suitably treated to enable them to withstand this
shock. As a single clutch is used for all speeds, it is made
with a very large surface, so that the wear on it is almost
negligible.

iNi>iviDrrAi.-ci.rrTcn tra.nsmis.sion ststem

6. In the individual-clutch system there is a separate
friction clutch for each speed. In Fig. G is shown a system
with two forward speeds and one reverse. The flywheel a
is keyed to the engine shaft and is connected to the shaft b
by the coupling c. From the shaft ^, motion is transmitted
to the propeller shaft d through the different clutches and
gears. Keyed to the short shaft b are the gears e and/* and
the friction cones ^ and //. The gear /and the clutch disk/
are parts of the same piece, which is provided with a bush-
ing k that fits loosely on the shaft b and is free to rotate on
the shaft. The collar / is loose on the shaft b and can be
moved by the lever m so as to force the end of the dog //
against the friction plate o and thus force the pin p against
the cone g.

On the lay shaft q is keyed the gear r, but the gears s
and /, which are provided with bushings, fit loosely on the
shaft. The friction cones // and v are keyed to the shaft q,
as are also the friction plates w and x. The col-
lar y also fits loosely on the shaft q and operates on the

§ 19 ENGINE AUXILIARIES 9

dogs z and ^,, throwing one or the other of them against its
friction plate and putting that gear into operation. There
is a small idle gear that stands behind but meshes with
the gears / and e. There is also a brake band at a^^
that may be used to prevent i and j from turning, or to
bring the moving parts to rest.

6, In the position shown in Fig. 6, the collar / has
pushed out the long end of the dog n and forced the friction
plate o against the pin/, causing it to force the cone g into
the gear % and the clutch disk j on the cone A, thus locking
the shafts b and d together. Consequently, the propeller
shaft turns with the same speed as the engine itself, which
is the highest speed that is transmitted. When the collar /
releadles the dog «, the cones g and h are disengaged by the
pressure of the small springs shown in the hubs of these
cones.

When a slow forward speed is desired, the collar y is
forced to the right, moving the long arm of the dog z^ out,
forcing the friction plate x against the gear j, and the gear
on the cone v. Consequently, motion is transmitted from
the shaft b to the shaft q by the gears / and s and the fric-
tion clutch V. From the shaft ^, motion is transmitted by
the gear r to the gear i and thence to the shaft d. It should
be noted that, as the gear f is smaller than the gear j, the
shaft q turns more slowly than the shaft b, and, as the
^ar r is smaller than the gear f , which is rigidly attached
to the shaft rf, the shaft d turns more slowly than the
shaft q and therefore much more slowly than the engine
shaft.

When the collar y is thrown to the left, the gear / is
locked to the shaft, and, on account of the intermediate gear
l>etween / and e^ the propeller shaft d turns in a direction
opposite to that of the engine shaft — that is, the motion is
reversed.

It should be noted that the gears s and / ordinarily run
loose on the shaft q and turn the shaft only when held by
the friction clutches. As these gears are constantly in mesh

AUTOMOBILE AND MARINE

gl>

with the gears e and /keyed to the shaft b, they produce
unavoidable friction, as do also the friction clutches not
engaged. On account of the unavoidable friction of the
constantly meshing gears, and also the dragging of the
disengaged clutches, this system is not verj- much used.

r^^^

PLANETART TR^VNSMISSION SYST£&[

7. Another speed-change system often used is knowf
the planetary system. It comprises a high-speed connec-
tion for the direct drive, and an arrangement of gears that
reduces or reverses the motion when one or another drum

on which these gears or pinions are mounted is held stB
ary. Most planetary systems give only two forward spi
and one reverse, but in some instances they are made to
give three forward speeds. They are used chiefly on small
automobiles, or runabouts; but when cheapness of construc-
tion is an object they are sometimes employed on touring cars.
In Fig. 7, is shown one form of planetary system. The
gear a is the only one keyed to the engine shaft h. The
gears c, d, and e all mesh with the gear a, and are made
long enough to extend beyond a and mcsb with tJis geais

§ X9 ENGINE AUXILIARIES 11

/i ^, and h in pairs. The last three gears in turn extend
"boyond the gears c^ d^ and e and mesh with the gear i^
iwliich is keyed to a sleeve connected to the drum j. The
grears Cy dy e^ /, g^ and // turn on pins fastened to the
dnim ky but only the gears r, rf, and e mesh with ^?, and
only y, ^, and h mesh with the gear i which turns loosely on
the shaft b. The internal gear / meshes only with the
gr^ars Cy dy and e^ and is rigidly connected to the sprocket m
that drives the automobile. The cover n is attached to the
^ace of the drum k by means of screws, thus forming an oil
reseirvoir that keeps the gears well lubricated when the
fi-utornobile is running. There are separate brake bands
aroimd the drums/ and >&, and a friction disk keyed to the
shaft just outside of the drum/.

W'hen the friction disk is pressed against the drum/, the
Z^^T i is held so that it must turn with the shaft; conse-
quently, the entire mechanism is locked together and the
^rocket tn turns at its highest forward speed. If now
the friction disk is released and the brake band around the
^rurn / is applied so as to hold it from turning, then
the gre^f ^ turns the gears Cy dy and ^, causing them to turn the
g'^ars/, gy and h ; but, as the gear i is held stationary with
the drum/, the gears/", gy and //, and also the drum ky to
^hiQ"h they are attached, must revolve around the gear i in
the same direction as the shaft turns, but more slowly. The
S^^Ts Cy dy and e turn on pins that are fastened to the
^^^m k\ consequently, they revolve with it as they turn on
^heir axes and thus cause the internal gear / ^nd the
Sprocket m to turn in the same direction as the shaft. This
S^ves the slow forward speed.

When the drum/ is released and the drum k is held by a
^*^e band, the gears r, dy and e are caused to turn on their
Ittns, and consequently drive the internal gear / in a direc-
tion opposite to that of the engine shaft, driving the auto-
mobile backwards. When the brake bands and friction disk
are all free from the drums, the gears turn idly, and if the
engine is running, no motion is transmitted to the sprocket
and the automobile stands still.
lefr-io

AUTOMOBILE AXIt MARINK

REVERSING (iEAHS

8, In motor boats, it is often desirable to run the pro-
peller backwards even when there is only one set of gean
for forward speed and hence no speed-change device. In
such cases, it is desirable to have a device by means of
which the direction of motion of the propeller shaft may be
reversed while the engine runs continually in the one direc-
tion. The reverse motion of the propeller is sometimes
needed to check the forward speed of the boat, to bring it
to rest, or to run it backwards. There are several forms of
snch reversing mechanisms, but they are all similar in prin-
ciple so far as the motion of the engine and propeller shaft
is concerned, differing only in the method of making tbe
connections for the reversal of motion. In some cas

gears and clutches are iisfd ; in others, spur gears and slid-
ing feathers; and in stiH others, bevel gears.

In Fig 8 (a] is shown a reversing gear that depends oa
friction clutches for its operation. The propeller shaft is
divided into two parts, the one connected to the propeller,
carrying the gear a, and the other, connected to the engine,
carrying the gear d. The gears c and f^ mesh with these
gears, and it should be noted that the gear b is slightly
smaller than the gear a and that c meshes with 6, and J

§ lo

ENGINE AUXILIARIES

1:3

^v'i 1 1:1 a. Another gear similar to f, but not shown, meshes with
^/ a-ncl d, while one similar to i/ meshes with a and c. The
g^SLirS'C and ^nm on pins that are held in place in the web
^f "ttie drimi e.

T^liere are two friction clutches y* and ^'', the latter serving
tc> hold the drum e stationary when the movement of the
P'i*op>eller shaft is to be reversed. To reverse the motion of
ttk^ propeller shaft while the engine is running, the spreader
^' is thrown inwards by the reverse lever, so that the
d'*"it:c:h^, which is stationary, grips the drum e and holds it.
'^h^ pins on which the gears c and d revolve are thus also
^^l-d stationary, and the relative motions of the gears are as
s^ c>^wn diagrammatically in Fig. 8 (b). The crank-shaft trans-
mits motion to the gear d, in the direc-
tion indicated by the arrow. The gear c
in mesh with b turns in the opposite direc-
tion and transmits motion through a long
gear c\ not shown in Fig. 8 (^), to the
gear a on the propeller shaft, which is
thus made to move in a direction oppo-
site to that of the gear d on the end of
the driving shaft. The gear d is also in
mesh with the gear d\ which turns gear
d in the same direction as that in which
the gear c^ moves, and hence helps to
gear ^ in a direction opposite to that in which the
^^^Aring gear b moves. The gears d' and ^are duplicates of
tri^ ^ears c and c\ each pair transmitting a portion of the
^^^^-v^er when the lever is reversed. When the reverse
^P^^aderA is thrown out of engagement and the fon\'ard
^P^^ader i is thrown in, the same movement of the reverse
'^^'^^T serving to accomplish both operations, the clutch /
^^I>s the drum e, which is thereby caused to rotate with the
^^VTiig shaft to which the clutch/ is keyed, all the gears
^ing locked together. The gears therefore have no
Tel^t{yg motion, and the whole mechanism, including the
Propeller shaft, rotates at the speed of the driving
Rliaft

7 10. 3 id)

14 AUTOMOBILE AND MARINE | 19

9, A somewhat different type of reversing gear is shown

a Fig. 9. The driving shaft a is connected directly to the

[ propeller shaft b by the clutch coupling c in the position it

I now occupies. In this position the gears d, e, BnA/Aa not
transmit power, but the gear / turns idly on the propeller
shaft By throwing the clutch coupling to the other side,
however, the shafts are disengaged and the clutch holds the
gear/ rigidly to the shaft b, and the direction of rotat joglt
reversed.

§ 19 ENGINE AUXILIARIES 16

DIFFERENTIAIi GEARS

PRINCIPLES OP OPERATION

10, • Differential gears are composed of a set of four or more
gears attached to the ends of two shafts that come together
and are usually in line, so that both are rotated in the same
direction; but if either meets with extra resistance it may
rotate more slowly than the other or may stop altogether.
These gears are used on the driving axles of automobiles.
The axle is made in two parts, with a gear on the end of each
where the parts come together; other gears mesh with both
these axle gears and are driven from the engine by a
sprocket and chain or by bevel gears and shaft. These
gears turn the axle, but permit its two parts to turn in
respect to each other so as to allow the automobile to go
around a comer without causing the wheels to slide or skid.
The rear wheels are each fixed to a half of the rear axle, and
both receive power, hence it is necessary to allow one wheel
to turn at a different speed from the other; this is done by
the differential, or, as it is sometimes called, the compensate
ing or equalizing gear.

SPUB-GEAIl DIFFERENTIAIi

11. A spur-gear differential is shown in Fig. 10 with
the ends of the two shafts, carrying the gears c and d.
The sprocket wheel e is driven from the engine by a chain,
and is in turn fastened to a gear-case that carries a series of
small gears f, g^ arranged in four pair, each gear being
mounted on its own axle. The two gears of each pair
mesh together, and one is in mesh with gear c while the
other meshes with gear d. By this arrangement both
gfearsV and rfare drawn in one direction, and yet they may turn
•with respect to each other when the resistance to the turn-
ing of one is gfreater than that of the other. When the

ENGINE AUXILIARIES 17

that for the spur-g«ar differential. When both gears meet
with the same resistance, the small bevel gears d do not
turn on their bearings; but when the movement of one of

the gears e or f is resisted more than that of the other it
lags behind, causing the small bevel gears to turn on their
axles sufficiently to cause the resistance to be equalize.

COUPLTNGS, CLTJTCHES, AND DRAKES

CO IT LINGS

13. Plain CoupllnKB. — Several plain couplings, such a3
ate used on propeller shafts of motor boats, are shown in
Fig. 13 {a\ (b\ and fr). The one shown in Fig. 12 {a) holds
the two ends to be coupled together by means of setscrews
through the holes shown in the sides of the coupling. In

AUTOMOBILE AND MARINE

§19

the one shown in Fig. 13 (6), the ends are clamped by means
of bolts, one end of the shaft being in one end of the coupling
and the other in the opposite end of the
coupling. In Fig. 12 (c) is shown the
flange coupling, one-half of which if.
keyed to each end of the shaft so that
the separate shafts are held together by
means of bolts through both flangea

1.4:> Compression Couplln^r- — A

modified type of flange coupling, known
as a coHifrcssion coupling, is shown
in Fig. 13 ((z) and {b), (d) showing
ihe separate parts and ip) the assem-
bled coupling. In this coiipling no
keys are used, but a loose sleeve a.
Fig, 13 (i7), fits over the ends of the
two parts of the shaft to be coupled;
the sleeve is tapered on the outside
toward both ends and has six slits,
three from each end, equally spaced
The loose sleeve a is first slipped in

around the sleeve.

r the shaft and liien the parts b and c are bro-jght

ENGINE AUXILIARIES

sleeve on the two parts o£ the shaft, owing to the taper on
the sleeve, holds them togetlier.

15. Universal Coupling. — It is often desirable to have
the propeller shaft so constructed that ooe part may stand at
an angle to the other. This may be done very conveniently
by means of a nnlversal Joint or coupHiiKt sometimes
called a crab claw, shown in Fig. H, The shaft a is con-
nected to the shaft b by the coupling shown at c. Two forks

V\0. 14

(/and e are connected to the shafts; on the ends of the forks
are balls /and ^, which tnrn in cups that are fastened to the
casing A, which turns with the forks. Each fork is thus per-
mitted free motion at right angles to its shaft. A coupling
of this type permits the shafts to turn freely so that power
can be transmitted through the two shafts at a slight angle
almost as readily as through a continuous shaft

When the power must be transmitted from one of two
parallel shafts to the other, the two must be connected by a
third, or intermediate, shaft with a universal coupling at
eadi end. In order that the motion of the driven shaft may
be the same as that of the driving shaft, the forks on the
intermediate shaft must stand in the same plane.

CXiUTCITES

16. Cone Clutches. — The clutches commonly nsed on
the power-transmission mechanism of automobiles and motor
txiats may be divided roughly into three classes; namely, cone

30 AUTOMOBILE AND MARINE § "

clutches, band clutches, and disk clutches. They are s
designed to permit the engine to be disconnected from tK
transmission gearing, either while the gears are being shifte
or when the machine is to be stopped.

The cone clutch is provided with a cone-shaped memb-
attached to one part of the shaft, and a tapered ring or cu_
into which it fits. When the cone is forced into the rin
both shafts are held firmly together by the friction of t^
conical faces.

There are a number of modifications of this t3rpe of clutc=
one of which is shown in Fig. 15. The flywheel a is fi

to the shaft b by means of bolts through the web of t*^
wheel. At c is shown an expansion ring into which ^"^
friction cone d fits. The helical spring e holds the co"^
against the expansion ring with the required amount o\
force. At /is a ball bearingthat takes the end thrust wh^"
the cone '\^ pulled away from the expansion ring. Tt**
arms .ifare coii])le(l to the propeller shaft that turns v "

i-ith

§ IS

ENGINE AUXILIARIES

tlie friction cone. Ordinarily, the two parts of the clutch
ar^ held together by the pressure of the spring, and when
it is desired to disconnect the cone, as when the speed
is Toeing changed on an automobile, a foot-treadle is forced
down so as to act on a fork and sleeve and pull the cone away
from the expansion ring. As soon as the treadle is released
the spring e forces the clutch into action again.

"17. Band Clutch. — Another type of clutch known as
the band, or frlctlon-rlng, cluteli is shown in Fig. 16.

FlO. 16

I he wheel, which is connected to one of the shafts, is shown

^^ ^, and the band or ring, which is connected to the other

^^aft, and which is made in two parts, is shown at b and c,

^^ d and e are curved arms pivoted at / and g. The links //

^^d j" connect these curved arms to the parts b and c of the

"^^nd. By means gf a fork and tapered sleeve, not shown,

l^e ends/ and k of the arms are forced apart when the clutch

is brought into use. This throws toward the shaft the

^^ds / and m of the levers d and e, and brings the two parts b

^^^ c of the clutch ring in contact with the friction or driv-

i"? surface of the wheel a, which is thereby forced to turn

^ith the driving shaft

AUTOMOBILE AND MARINE

ILS

18, Disk Clutch. — A clutch of the multiple -disk type i s
shown in Fig. 17. A two-arm spider a keyed to the shaft ^
serves to hold in place a number of metal disks ^, betwe^sn
which are other metal plates d held on the sleeve f by mea.:i:».s
of a key/! The sleeve eis in turn keyed to the shaft/; a-X3<3
to it is screwed a ring A having three pair of lugs carryiir^s
three levers i with rollers_/' at their outer ends, as shown. TT^a.*
other ends of the three levers press against the plate i wh.^M
the clutch is engaged byan inward movement of the collac" ^,

the plate i being free to move along the key^l The dislesf
are free to move longitudinally on the arms of the spidex"./
and also on the sleeve c, around which they rotate when, t Jie
clutch is out of engagement; but the arms of the spid^f.
fitting into slots in the disks, cause them to rotate with t*"^
shaft d. The plates d are free to move longitudinally d
the key y in the sleeve c; and since the sleeve is keyed to tfie
shaft j^, it is evident that, when in engagement with tli^
disks f, the plates d must cause the shaft £- to turn wi tf*
the shaft b. The disks c and the plates d run in an oil batl^'
obviating wear of the plates and disks. These are broug'ti*
together forcibly by throwing the cone-faced end of the coll^*"
/ against the rollers /, thereby causing the ends of the thr^*
levers / to press the plates and disks together with sufficiei^'
force to cause the shafts * and ^ to rotate as one shaft.

§19

ENGINE AUXILIARIES

BRAKK8

19. The power- transmission system of an automobile is
usually fitted with one or more brakes. The most common
arrangement is to have a brake on the propeller shaft and
one on the hub of each of the rear wheels. The brake may
be of the expanding type
placed inside some wheel as
a flywheel, or it may be on
the outside of a wheel, in the
form of a band. The band
brake is often applied to the
hubs of the rear wheels and
is operated by means of a
treadle. A rear-hub brake
is shown in Fig. 18, with the
hub at a and the brake band
at b. The connecting-rod c
from the treadle to the lever d tightens the brake by draw-
ing the link e down and shortening the brake band b. The
lug f is held from turning with the hub by the arm that
extends from the axle casing to the pin g. Releasing the
treadle allows the rod c and the lever d to move back and
thus throw off the brake.

AUTOMOBILE AXD MARINE

MTAKTIN*; AM> UO^'ER^^^'a DEVICES

HTABTEBS

HAND Ml'ARTER FOH AUTOMOBEUBS

20. The most common method of starting automobile
unftincs is by. means of a simple hand crank that can be con- '
necteil to the engine shaft and by means of which the shaft
(.'iin hv turned by hand until a charge is dra^v^ into the
cylinder, compressed, and
ignited. Some cranks are
made so that they will dis-
engage as soon as the engine
starts, and also so that,
should the engine explode
a charge and start back-
wards, the backward mo-
tion, frequently called a
l-ii:k, will not injure the
oiDcrator. A crank of this
type is shown in Fig. 19.
The handle a is connected
to the end of the long
sleeve A by the pin or latch
<-, which is held in one of
a number of equally spaced
slots in the end of the sleeve
The ratchet wheel c is
.iu:i.':;iobile and is thus held
'I s;:rKo:ent siie to permit the
led .i:-.,'. fitted to the cranfc-
r.otchos of the ratchet whee\

iiio the crank at .;

S19

ENGINE AUXILIARIES

and is rigidly connected to the lever ^. The pin h and the
spring I hold the lever g against the pin /, which is fast-
ened to the latch c, and also hold the pawl _/"down to the
ratchet wheel. The slot k in the sleeve fits on a pin in the
cranlt-shaft of the engine, so that as the crank is turned in
the direction of the arrow it turns the crank-shaft, but it
canaottum the crank-shaft in the opposite direction. If
the engine should kick backwards, the pawl / would be
stopped by the teeth of the ratchet e, and in turning would
'^ise the lever ^, lifting the piny and the latch r, thus per-
"lilting the sleeve b to turn freely without carrying the
fandJe with it.

AUTOMATIC BTARTKRS FOR AUTOMOBItBS

Si, In Fig. 30 is shown a small hand air pump that is
attached to the side of the car near the driver's seat. The

26 AUTbMOBILE AND MARINE § 19

cylinder a is of rather large diameter, the piston rod b car-
ries a handle c of convenient size, and the pump is placed in
the most convenient position for the driver to operate with-
out leaving his seat. The object of the pump is to com-
press air for starting, the air passing over gasoline in the
surface carbureter d on its way to the valves e through
which the starting charge is admitted to the cylinders. To
start the engine, the valves e and compression relief cocks/
are opened by means of the operating handle g" attached
to the rod A, the driver gives the pump plunger a few
strokes, and the air is driven through the carbureter d to
the explosion chambers of the engine cylinders. The
charge is then ignited and the engine started. Air for
the compressor is drawn into the pump cylinder a on the
up stroke through the flap valve /, and is expelled on the
down stroke through the outlet valve j\ which is seated
by a spring, as indicated. Simultaneous operation of the
relief cocks and charging valves is effected by connecting
the rods k and / to the lever m attached to the rod A.

MARIN£-£X6n>rE STARTERS

22. Marine gas engines are usually started by hand.
Some four-cylinder marine engines, however, are equipped
with air starting and reversing mechanism, one type of
which is shown in Fig. 21. This mechanism consists of a
hand bicycle tire pump, two check- valves, a priming cup,
piping to the two after cylinders, and stop-cocks therein.
A plain lubricator a is used as a priming cup, b, b are two
check valves, c is the tire pump, d and e are stop- valves
that are sometimes placed at /, /, and g^ g are the two after
cylinders, that is, the two cylinders toward the stem of the
boat — of a four-cylinder engine. The priming cup is partly
filled with gasoline, which is allowed to run into the base of
tHe pump. The engine is turned over by hand until the
piston has slightly passed the upper center and the igniter
has snapped. The piston in the other cylinder will now
have begun to start on its compression stroke. The valves

§19

ENGINE AUXILIARIES

d and e are opened, and pressure is pumped up in the
two cylinders. The valves are closed, and the igniter in
the cylinder with the piston just past the upper or outer
center is snapped by the finger, when, if the proportions of
the charge in the cylinders are correct and all other condi-
tions are right, the engine will start. The advantage of a
compressed-air starting and reversing mechanism for start-
ing the engine in either direction lies in its small size and

PIG. 21

low first cost. In operation, different sets of cams and
usually auxiliary air valves are employed to control the
movement of the engine.* In six-cylinder engines, only
three of the cylinders are equipped with the air attach-
ments, the other three taking up their cycle of operation
when the mixture ignites, whereupon the compressed air is
shut off and the regular inlet- and exhaust-operating cams
come into operation in place of the air-valve operating cams.
With some large engines, a smaller engine is sometimes
employed to start the larger, the small one being discon-
nected as soon as the larger one starts.

158—11

28 AUTOMOBILE AND MARINE- §19

GOVERNORS

AUTOMOBILE OOVERNOBS •

23. Automobile engines are controlled by manipulation
of the throttle valve and the position of the spark, some-
times called the spark lead. More accurately, the control
proper is accomplished by regulation of the throttle, and
the spark advance is regulated to keep the ignition at its
most advantageous point for developing the maximum
power of the charges received.

The manipulation of the spark is sometimes employed to
modify the speed of the engine, because, with the spark
retarded to cause ignition to occur later than it should, the
power of the motor is very materially reduced. This, how-
ever, is a most objectionable practice for several reasons:
In the first place, it evidently wastes gasoline, because the
same result as regards power may be obtained with smaller
charges and an earlier spark. Second, the inflammation is
so prolonged that it probably is not completed at the time
the exhaust valves open, so that the valve seats are exposed
to streams of gas still burning. This not only overheats
the valves and is liable to warp them, but it soon burns and
cuts their ground faces and their scats. Third, the motor is
overheated dnd preigiiition of the incoming charge may
result, producing explosions in the carbureter and intake
pipe. It is, however, permissible to retard the spark to
prevent racing, that is, running too fast, when the throttle
is nearly closed and the motor is running light, with the car
standing still.

24. Since automobile motors are operated under wide
variations of speed and load, it follows that for correct
action the throttle and spark cannot always be operated
together For example, a rarefied charge, such as is
obtained with the motor runnin.cf at medium speed, with
the throttle nearly closed, will bum comparatively slowly

§ 10 ENGINE AUXILIARIES 29

aricl requires an advanced spark for its prompt combustion.
Suppose, now, that the car is running at moderate speed
under these conditions, as it may when descending a slight
grade, or even on level ground. If a slight up grade is
encountered, the operator will open the throttle to increase
the power. Under such conditions the speed of the motor
will probably not increase, but it will be found that the
spark advance suitable for the previous conditions is too
early for the increased charges. This will be indicated by
the laboring sound and possible pounding of the motor,
either of which sounds may be stopped at once by slightly
retarding the spark.

If the throttle and the spark mechanism were positively

connected, it would be impossible to advance the spark

while closing the throttle, as was required for the first set of

conditions, and to retard the spark while opening the throt-

^^^, as was necessary for the second set of conditions.

-Although having the two positively connected simplifies the

pperation of the car in the hands of the novice, and although

'^ is undoubtedly satisfactory under some conditions, as for

example when the car is speeded along a level road, it is

'^^t flexible enough to give the most favorable results in

Either speed or fuel economy.

A simple automobile governor acting on a throttle
^"^Ive located in the intake pipe is shown in Fig. 2'2. The

yl^alls a, a are revolved about the engine shaft b and fly
^Ut^vards against the resistance of the spring c under the
^^^ion of centrifugal force. The fly balls move the sleeve d

^t. Wards as the speed of the engine increases and inwards

^ it decreases. The rocker e pivoted at/ moves with the
^le^ve ^ and transmits its motion through the rcxl^to the

^^ottle valve // in the supply pipe /".

^6. Small engines are commonly controlled entirely by

^^d, there being no centrifugal governor on them.

"^^tiiost all automobiles with four-cylinder engines of

*^ liorsepower or more have centrifugal governors, whose

^Unction is partly to prevent the engine from racing when

30 AUTOMOBILE AND MARINE |U

the clutch is released, and partly to facilitate the control of
the automobile by making the engine semiautomatic in iu
speed regulation, thus relieving the operator of part of the

attention to the throttle, otherwise necessary. When the
centrifugal governor is employed, it is always arranged to
be modified in its action by the operator. This may be
accompliHhed in several ways, of which the simplest is to
open or close the throttle forcibly against the resistance of
the governor mechanism. This may be done by running a
connection from the long upper arm of the governor lerer
to suitable controlling mechanism under the operator's
hand. The usual connection would be a slotted link,
attached to the governor lever so as to permit the governor

§ X9 ENGINE AUXILIARIES 31

flyl)alls to approach each other but not to separate, and
would therefore limit the degree to which the throttle was
pexTnitted to close.

27. A'more elaborate arrangement than that shown in
^i& 22 is shown in Fig. 23. It has the special feature that
the hand regulating device imposes no stress on the governor
niechanism, and friction and wear due to this cause are
^lixninated. The fly balls a of the governor revolve around
the engine shaft by their outward motion being resisted by
^o spring c. The sliding collar d and governor lever e act
^i>. the throttle arm / through a slotted link g, and as the
flyl>alls separate, this link is simply shifted to the left and

7o^

^^■

•

Pig. S8

the throttle is closed by the tension of the spring A. The
^nd regulation is effected through the rod i, which works
freely in an army connected to the throttle arm, and has an
^instable nut and locknut at its end, by means of which
^^ throttle may be pulled open against the tension of
^P'^ng A. When the throttle is thus forcibly opened, the
^^t in the link ^permits the governor mechanism to remain
^ its natnral position, as determined by the speed of the
^Rine. As i is rigidly connected to the hand control lever.

32 AUTOMOBILE AND MARINE §19

the effect is to limit the degree to which the throttle can
close, this restriction being independent of the action of
the governor. Consequently, if the rod / is pulled to the
right as far as it will go, the throttle is held wide open.

MARINE-ENOrNnB GOVERNORS

28, Governors are not used on marine engines to any
great extent Several makers of engines up to 100 horse-
power or more have never adopted them, or have dis-
carded them after several trials. Small engines rarelv have
them, except when used for some special purpose. When
governors are used they are almost always of the throttling
type, similar in principle to those used on automobiles.

The governors in use are usually within the flywheel, or
are mounted on the throttle valve and operated by a belt
from the crank-shaft, and are of the centrifugal type.

They are quite convenient when using a reversing gear,
but very many engines have been wrecked when too much
dependence has been placed on the governor and it has
failed to act, as, for instance, through the breaking of a belt
or spring or a stud carr^^ing the lever arm.

If the engine is of the automobile type with very light
reciprocating ])arts, it gathers headway more rapidly than a
heavy lo\v-six.'ed engine, and for this reason is much more
likely to be wrecked should a governor fail to work
properly.

It is an excellent plan to have a switch in the battery cir-
cuit convenient to the steersman, so that the current may be
shut off should an emergency of any kind develop that
would necessitate suddenly stopping the engine. Some
cn^i^'incs are so installed that they may be handled from two
or more parts of the boat, and in this case the danger
rcfcn*ed to would be considerably lessened.

§ 19 ENGINE AUXILIARIES 33

COOIiING AND MXirFLING DEVICES

WATEB-COOIiING SYSTEMS

MABINS-ENGIXE COOIANO

29. Marine engines are cooled by the circulation of
water through the water-jacket of the engine cylinder. A
pump attached to the engine draws water through the bot-
tom of the boat, sends it to the engine, and finally dis-
charges it into the exhaust pipe, which is sometimes led
under water, discharging through a special fitting, one form

(a)

Fio. ^

of which is shown in Fig. 24 (a). The exhaust enters the
fitting at a and leaves at ^, under the water, the boat mov-
^S m the direction of the arrow. On account of the veloc-
^ of the boat, water rushes into the opening c, through
^® gradually reducing passage, into the exhaust pipe, and
o^t with the exhaust at d. This arrangement tends to
increase the velocity of the exhaust and reduce the back
pressure on the engine.

Another form of exhaust nozzle is shown in Fig. 24 (^).
This form resembles that shown in Fig. 24. (d:), except that
the passage c is omitted.

34 AUTOMOBILE AND MARINE §19

ATJTOMOBrLE-ENGnOC COOUNO

30. In automobiles, the circulating system is open to the
atmosphere, and it is important that the water used for
cooling should not be allowed to boil, because it wotdd
soon be exhausted. Since it is impossible to cany a
large supply of water, it is necessary to use coolers, or
radiators, as they are called, through which the water is
circulated, and which have a large metal surface exposed to
the air.

Owing to the considerable amount of power developed
by many automobile engines, and the necessarily small
amount of cooling water that can be carried to sup-
ply them, highly efl&cient means must be adopted for dis-
persing the heat as fast as it is received by the water. As
the only way of accomplishing this, without the evaporation
of the water, is to give the heat to the air by convection, it
follows that the logical method of cooling the water is to
spread it in as thin sheets as possible over metal surfaces
exposed to free currents of air set up by the movement of
the vehicle, by a suitable fan, or by both.

31, In a few makes of cars of moderate power, gravity
circulation alone is relied on to keep the water in motion.
In this case the bottom of the radiator should not be lower
than the bottom of the water jacket, and the top of the
radiator should be as much higher than the top of the jacket
as conditions will permit. The arrangement of the piping
for gravity circulation is shown in Fig. 25. The vertical
radiator tubes ^, a are connected at top and bottom by mani-
folds b^ c, or chambers with suitable connections for the
pipes. The water leaves the top of the water-jackets rf, d,
enters the manifold b, descends through the tubes a to the
lower header c, from which it flows back to the bottom
of the jacket. As the water cools in the tubes or, a, it
descends; and as it becomes heated in the jackets d, d, it
rises; thus causing a continuous circulation. As it is essen-
tial that the return pipe be filled with water (else the dr-

§19

ENGINE AUXILIARIES

culation would at once stop), it is customary to make the
top manifold b large, as illustrated, forming a small tank

Fig. 25

^^'^taining a couple of gallons or so of water that will take
^^^irie time to evaporate.

In any cooling system where the supply of water
^^ limited, it is very essential that the movement of the
^^ter shall be rapid, and this means that there will be a

^fiference of only a few degrees between the temperature of

^^ 'water entering and that leaving the radiator. With so
^^^^11 a difference in temperature, and therefore in density,

^^ impulse toward circulation in the gravity system is very
^^^11, and it is of first importance that the pipe connections
^^t.'Vreen the jacket and radiator shall be very large, short,
^^^ devoid of sharp bends. In fact, it is not uncommon

^ lase two or even three connections from the radiator to
^^^ bottom of the jacket, in addition to making the upper
^^"'inections as large as possible.

In the majority of cars, gravity circulation is not

^^l^ied on, either because it is not convenient to make the

^^ter connections sufficiently short and direct, or because

^*^^ motor rises too high in the frame or is of too high power

^ "be cooled in this way without employing a radiator of

36 AUTOMOBILE AND MARINE |1)

§ 19 ENGINE AUXILIARIES 37

undue size. Consequently, a circulating pump is usually
employed.

A cooling system of this type is shown in Fig. 26, with
the circulating pump located at a^ the radiator at /;, the
engine water-jackets at r, c^ and the carbureter at d. The
water circulates through the pipes in the direction indicated
by the arrows. It will be noticed that the carbureter is
surrounded by a water-jacket, through which a sm^ll
amount of water is circulated to warm it, the water passing
to the radiator, where it mixes with the other water as it
goes to the pump.

li^VBIATOIlS

34, Types of Badiators. — Radiators are usually made of
thin metal with as much surface exposed to the air as pos-
sible, and they are arranged so that the air can circulate
easily through them. Four forms of radiators are shown in
Fig. 27 [a), (*), {c\ and {d). The first, Fig. 27 {a\ consists
simply of a zigzag coil of copper tubing, on which are soldered
a large number of thin flanges that increase the surface
available for contact with the air. The one shown in
Fig. 27 {V) is quite similar to that shown in Fig. 27 (^), but
somewhat more complete, in that it has headers at the ends
to which the flanged tubes are connected. The whole
arrangement is enclosed in a sheet-metal casing having the
outline of the automobile front. The one shown in
Fig. 27 (c) consists essentially of top and bottom headers
connected by a large number of thin flat tubes, crimped into
zigzag shapes and placed vertically as close together as pos-
sible. In this way the water is divided into a large number
of thin sheets contained in passages between thin metal
walls, through which the heat of the water passes rapidly to
the air drawn through them by the speed of the vehicle,
aided usually by a suction fan just behind the radiator.
Circulation is generally maintained by a pump, and the
water enters the top of the radiator from the water-jacket,
and goes out from the bottom to the pump and thence to
the bottom of the jacket.

s AUTOMOBILE AND MARINE

Fig. 27 {iff shows the back view of a type of radiator that :
[ ctMisJsts of a shell with front and back tube plates into vrhidi
I are connected a large number of small horizontal tubes.

The water inside the radiator surrounds the tubes, and tjip J
r that does the cooling passes through tliem. Tho £
\ aids in the circulation of the air. It is held in place \

§ 19 ENGINE AUXILIARIES 39

three braces by c, and d. The water enters the radiator at
the upper right-hand comer through the connection e, and
leaves through the opening /at the lower left-hand comer.

35* Bemoval of Scale From Radiators. — Owing to the
narrowness of the water spaces in all forms of radiators, it is
extremely desirable to keep them as free as possible from
deposit and sediment of all sorts. On general principles, it is
well to empty and wash the radiator occasionally, and in
regions where the well and spring water is hard, rain water
only should be used when it can be had. The use of hard
water has the result, if the water gets hot, of precipitating
in the jacket or radiator a scale exactly like that which forms
in boilers. Even if the radiator is of the tubular type,
this scale is objectionable because it interferes with the free
transfer of heat from the water to the air.

Carbonate of soda, or common washing soda, is used for
the removal of scale from radiators. It breaks up the hard
deposits of scale into a powder or sludge, which can easily be
removed by subsequently flushing out the radiator and pip-
ing thoroughly with water.

The water in the circulating system is drawn off and
measured, care being taken that none is left in the pockets
to dilute the soda solution. The solution is made in the pro-
portion of 2 pounds of soda crystals to 1 gallon of water.
The circulating system is entirely filled with this solution,
which is allowed to remain all night. After drawing it off
in the morning, a hose is connected and a good stream
of water driven through at the best obtainable water pres-
sure for some time, or until the water comes off clear.

CIRCULATING PUMPS

36, Types of Clrcvilatlng Pumps. — Of the various
types of circulating pumps, by far the most common, and in
some respects the most efficient, is the centrifugal pump
shown in Fig. 28. In this pump the only moving part is a
bronze or aluminum disk ^, keyed on a shaft b, and on

AUTOMOBILE AND MARINE

§19

one face are cast blades c^ r, which may be radial, as shown,
or bent backwards. The shaft carries the disk a at one end,
and works through a stuffingbox to prevent leakage. The
water enters from the opposite side of the pump through an
opening indicated by the dotted circle d^ but which is on the
side toward the observer, so that the water as it enters the
pump meets the blades c. The water so entering is caught
by the blades and thrown outwards by centrifugal force,
being expelled at r. It is not necessary that either the disk
or the blades have a water-tight fit in the casing, since the

pump simply establishes a
difference in pressure between
the points d and ^, but does
not positively force the water.
Consequently, if the flow is
obstructed for any reason, the
pump can still be revolved
without injury to itself. More-
over, th's type of pump does
not lose its efficiency through
wear. The pump is run at
quite a high speed, generally
about twice the speed of the
engpine ; and.if the resistance to
circulation is not too great, it will throw quite a large stream
of water. It is usually mounted on the crank-case of the
engine and geared to the cam-shaft or to the two-to-one
pinion.

37. A type of pump used to some extent for circulating
]nirposes on automobiles is shown in Fig. 29. It is called a
^(^ar-punip, iind it operates equally well in either direction.
( )ne of the two gear-shaped pump members a is driven bv
a shaft, and it rotates the other with it. If the direction of
rotation is that shown by the arrows, the water will enter at
/;, and pass out at c. beine:" carried around by the outer teeth
d, d, and c, i\ and expelled as the teeth come together. The
particular pump shown has grooves/, f\n the sides and tips

Fig. 28

ENGINE ArXIIJARIES

s teeth, which, it is claimed, prevent lo a large extent
i past the teeth, and thereby increase considerably
ciency of the pump.

, ^^8. Another type of pump is shown in Pig, 30. It con-
■^ts of a cylindrical barrel a revolving eccentrically in the

chamber i. The shaft on which a turns is central with a,
and the water is moved by the two blades c and (/, pressed
iiHtwards by the spring r. The action of the pump depends
on the motion of the blades c and 1/ in the chamber i^. Sup-
itee barrel « to be in the position shown and rotating in

AUTOMOBILE AXD MARINE

l«

the direction of the arrow until d has co^-ered the edge/ of
the iataee port; the water in front of the blade d will Uien be
driven before i/and out by the port/: Meanwhile, as sooi
as d has covered /, water is drawn into the space h behind d
until d has nearly reached the position of c. This operalicm
is repeiited by the tn'o blades, thus producing an almost
continuous flow of water.

39. Circulation Pressnre Gange. — In order that the
operator of an automobile may know whether or not the
cooling water is ctrcnlatiiig
properly, a pressure gauge
such as is shown in Fig. 31 is
placed in the piping circuit
The gauge, which is frequently
styled a telltale, is usually
attached to the dash in such a
position that it may readily be
seen, the pressure created by
the pump and registered by
the gauge in ounces per square
inch giving some idea as to the
velocity with which the water
^'^- " . is passing through the circu-

lating system. If the gauge fails to register, it is evident
that no water is flowing through the piping.

MUFFLERS

40. Automobile and marine mufflers are generally very
similar in construction, except that the marine types are
often water-jacketed. Especially in automobile types, it is
desirable that they be as light in weight a» they can be made
and do the muffling properly, A muffler of this type, in
which the gasesaro deflected by a scries of conical baffle plates,
is shown in Fig. 32. The exhaust gases enter through the
pipe a, flow into the central tube b, and a small portion passes
out through the oi«ning in the nozzle c to the outlet pipe i.

ENGINE AUXILIARIES

4:i

The velocity of the gas through the nozzle creates a partial
'■■acuuin in the chamber c. The opening in the nozzle being
soiaH, a portion of the exhaust gases flows around the end of
the tube b to the chamber/. The partial vacuum me draws
the fases through the baffle plates^, one being perforated

'^^ar the center, and the next near the outside, so that the
Sases move in the direction of the arrows. The body of the
"muffler is composed of two steel cylinders, with asbestos
packed bet\veen them, and closed at the ends by flanged heads.
^liis muffler does not create an excessive back pressure on
^oe engine, and reduces the noise considerably.

41, Another type of muffler is shown in Fig. '.i'i. The
ffases enter at a, pass to the opposite end through the pcrfora-

^"■itis, and around the ends of the baffle plates b and through
^ openings r Tbey then pass back outside the cylinder d.

44 AUTOMOBILE AND MARINE §L

through the openings e in the cylinder f^ and finally o
through the openings^. A relief valve // is held in placr
against the openings i by a spring. When the back pressur'
becomes excessive the valve opens, or it may be opened b
a treadle near the driver, the treadle operating through a r
attached to the lever /

42. Two forms of mufflers for marine engines are knowr::^^^^^^-*'
as the ivet and jacketed viufflers or the construction maj
represent a combination of both of these types. In the
Jacketed muffler, water from the cylinder water-jacket
outlet is allowed to circulate around the outside of the muf-
fler, to assist in cooling the gases and thereby reducinj
their volume. The 'wet muffler is one in which all or
|xirt of the exhaust water from the water-jacket is dis-
charged into the engine exhaust, where it is turned int(
steam, cix^s the exhaust gases, and combines with them,
incre;ising their density and sluggishness, and thereby muf-
fling the exhaust. The water from a jacketed muffler ma;
Ik divortevl into the exhaust itself, to further reduce the
souuvi of the exhaust, this being the combination systenc
alx>vo montionoi!.

Mut^ing a well-designed engine results in more orle

Kick pressure in the exhaust, and as a result the product
ot oxMuhusiion arv not so thoroughly removed from
explvvsion chamber, with a resulting loss of efficiency. It -i s
t\^r this reason that many marine engines are but slight"Xy
wurtk\K the :nort>ai<xl noi^e not being quite so objectionat^l^
as it woulv! !x^ in an autv^mobile used in the streets.

ENGINE AUXILIARIES

SCREW PROPELLERS

Types of l*wjpellers. — The screw propeller is a very I
tanportant part o£ the power equipment of a launch orl
"lotor boat. The rotary motion imparted to the crank-shaft-l
^ the gas engine inside the boat is given to the propeller J
outside the boat, and by its action on the water the boat i
propelled forwards or backwards. Motor boats are sel'' 3m I
T^m backwards for any
ffneat distance, the back-
Ward motion being prin-
cipally used when get-
ting away from a wharf
*T dock, when stopping
quickly, or when turning
"^ a small space. The
**oat always moves more
rapidly forwards than
"ackwards, with the same
Expenditure of power, '

I^'igfi. 34 and 35 show
two forms of propellers.
^>gr. 34 has a very wide
bla.tic near the end, while Fig. 35 has the greatest width at !
* point about one-third the distance from the end of the |
olacJe. Propellers are also made with two and with four |
'''acles; when made with two blades they are opposite, or J
^^O" apart. The blades on a four-bladed propeller are J
dually spaced around the hub.

■As the propeller turns in the water, its motion is resisted
"^ the water, and this resistance increases with the speed of
'**^ propeller; besides, when a propeller turns very rapidly,
't Chums the water without increasing the speed of the boat.
"^^e speed limit of propellers seems to be reached in prac-
tice at about 800 revolutions per minute ; it is probable that,

4H AUTOMOBILE AND MARINE

at speeds in excess of 800 rKvolutions per minute, cvenn
e in power at the engine is tnoie
than CO unterb;t lanced
.!'! neutralized by pro-
"J llcr losses. In heavy,
, ■■; working, boats, the
] OSS of efficiency at high i
■^pt-ed is verj- much
;;ri;aler than in lighl
boats. It has been ob-
served that, in heavy
head winds, working
boats that make but
little progress witl) the
engine running at 3fi(l
'^'^- " revolutions per minute

will do considerably better at 20 per cent less speed.

44. Pitch or PropeUer. — The pitch of the propeller

is the axial, or longitudinal, distance through which the
propeller would force the boat, in one revolution, if there
were no resistance. The amount the resistance reduces the
longitudinal motion of a boat is called the slip. The pitch
of a propeller is measured in the same way that the pitch of
a screw is measured. If a screw has eight threads in I indi
of length, the distance from one thread to the next is \ inch
and the pitch is consequently \ inch; that is, in moving a
point around the screw thread once, it advances \ inch along
the axis. In the three-blade propellers shown in Figs. W
and 35, it will be noticed that there are three distinct sur-
faces, all of which have the same pitch, and that these
surfaces resemble a portion of ascrew with three threads.

The diameter of a propeller is the diameter of a circle
described by the tip of the longest blade. If the circumfBT-
ence of the circle of any point on a blade is laid off on a
straight line, the pitch laid ofEat right angles at one end, and
the triangle completed, it will form a right triangle, as shown
in Fig. 36. Let the base a b represent the circumfer

§ 19 ENGINE AUXILIARIES 47

of a circle described by a point on the tip of one of the
blades of a propeller; b r, the pitch or distance advanced
along the axis in one revolution ; and a c^ the line complet-
ing- the triangle. The line a c then represents the direction

PlO. 86

of the face of the propeller blade, and the angle bac\^ called
the angle of advance. The circumference for a point one-
half the distance from the center of the axis to the tip of
the blade is one -half as long as the circumference for the
point at the tip. Let the point d be located, on Fig. 36, mid-
way between a and b\ then, if the pitch is the same, the angle
of advance b d c \s greater than the angle of advance^ a c.

4:5, A propeller with the same pitch for all points of the
blade is said to have unifonn, or true, pitch. A pro-
peller blade has increasing:, or expanding:, pitch when
the pitch increases from the axis to the tip of the blades,
and decreasing pitcli when the pitch at the axis is great-
est and it decreases toward the tip of the blade. Com-
poand pitch is any combination of pitches. The propeller
might have true pitch at some parts, and increasing or
decreasing pitch or both at other parts.

Fig. 37 shows, diagrammatically, the difference in the angle
of advance for different points of blades having true, increas-
ing, and decreasing pitches. Let the length of the line a b
represent the circular distance traveled by the tip of the
blade in one revolution, and let b c represent the pitch of
the blade at the tip. Let the points d^ t\ and f be at
three-quarters, one-half, and one-quarter the distance
a b from b and on the same blade. Then, for true pitch
the length b c \^ the pitch for all these points, and
the lines drawn from c to /", ^, d^ and a make decreasing

48 AUTOMOBILE AND MARINE g 19

angles with the line a b, that is, for a propeller of nnifonn
pitch, the angle of advance decreases from the axis toward the
tips of the blades. If, on the other hand, lines are drawn fTom
d, e, and / parallel to a c, as d g, e h, and ft, making the same
angle with a b — that is, if all points of the propeller blade
have the same angle of advance — the pitch increases from the

axis to the tips of the blades. The pitch at one-quarter the
distance from the axis to the tip is b i; at one-half it is b h, at
three-quarters it is bg; and at the tip, it is i c. Propeller blades
having such angles would be said to have increasing pitch.

Continue the line b c beyond c, and lay off the points/, k,
and /, and draw the lines dj, e k, axiA/l. When these lines
represent the angles of the faces of the blades at different
points, the pitch from the point / where it is b /, decreases
toward the tip, where it is b c. Conse'qnently, such a pro-
peller would be said to have decreasing pitch.

46. Measuring Plteh of Propeller. — In practice, the

pitch of a propeller may be found quite closely in the man-
ner illustrated in Fig. 38. Take a piece of joist or lath />.
which should be as straight as possible, and place it so that

§19

ENGINE AUXILIARIES

it touches one of the blades at any distance, as d, from the
axis A By taking care to hold it parallel with the axis.
Next take a carpenter's square, shown at £, and place it on
the lath and against the blade, so that the point at which
the square touches the blade will be the same distance from

Fig. 88

the axis as is the lath. Measure the distances a, b^ and c —

a being the distance from the square to the point at which

the lath touches the blade, and c the distance from the point

at which the square touches the blade to the lath. Then

the distance c is to the distance a as the circumference at this

point is to the pitch. Expressed as a formula, the pitch is,

6.2832^*

^ c

where/ = pitch of blade;

a = measurement taken along axis;
c = measurement at right angles to a
b = radius where pitch is taken.

ExAMPLK.— If the distance a is 10 inches, b 12f inches, and c 20 inches
what is the pitch ?

Solution. — Apply in j2f the formula,

6 2882Xl0Xl2.fi25

i> =

- = 39.66 in., or, sav. 40 in. Ans

H 50 AUTOMOBILE AND MARINE 1

^B 47. It nfLen Ikcoihis necessary tu measure the pil
^M a propeller accurately, and the only manner in which it c
^H doneisbydran'ingtwciprofilesof one of the blades. gOi

— ^J

:=j:rz^

fc.-.-. '^

Fin. at ^H
|^«j|kf, -"^■■"' - -rMeron astcelmanarel^B
^^H| : ■■■.-asary tncasuremenix. ^|
^^^ftl o-'tcr, and long oaaugh^^l

ENGINE AUXILIARIES

§19

through the wheel, with a round shoulder at ^ 2 inches in
diameter, and an extension c )-inch in diameter and \ inch
long. Two roimd hardwood tapered bushings d and e should
fit the two ends of the hole in the propeller, and the mandrel
inserted so that the wheel shall retolve at right angles to
the mandrel. It may be necessary to add washers at/to

allow the front or cutting edge of the wheel to be above the
lower surface of the shoulder b. The mandrel should then
be set into a drawing board g, on which are circles con-
centric with the mandrel, as shown. A line a b can be
drawn as shown on Fig. 40, the axis laid off at c d,
and lines drawn parallel to c d and spaced the same dis-
tance apart as the circles in
Fig. 30. Then, by taking
a square, as shown at //,
the height of the lower side
of a blade can be measured
as shown at t, and this dis-
tance laid off on the corre-
^"'"^' sponding line, as shown at

i in Fig, 40, Then the square can be set on the other side of
the blade on the Sfiine circle, the highest point measured as
at/ Fig. 3i), and laid off as shown at J in Fig. 40. If the
angle of the square is set carefully on the circle, the point
where it touches the circle marked, and the process repeated
on both sides of the blade for eacli circle, a line can be
drawn through these points, giving the end view as shown in

52 AUTOMOBILE AND MARINE § 19

Fig. 41, in which twelve measurements are taken. Having
done this, the pitch can be calculated along any of the
twelve circles by the formula in Art 46, taking the lengths
of the arcs in Fig. 41 to represent c of the formula, the
lengths of the corresponding straight lines in Fig. 40 to
represent a^ and the distances of the circles from the center
to represent b.

When it is desirable to get increased blade area without
increasing the width of the blades and making them corre-
spondingly stronger, it is customary to use three or four
blades.

The heavier the boat and the slower the engine speed, the
greater the blade surface should be; while the lighter the
boat and the higher the engine speed, the less the blade
surface required, other conditions being the same.

48. Propeller Blades. — The drlvingr snrfoce of a pro-
peller is usually the flat side of the blade that pushes the
water astern, while the crownings surftice, or firont, is the
part that draws the water toward the propeller.

The cutting edge is the part of the propeller blade that
first enters the water when driving the boat ahead.

The projected area of the blades is the surface that forces
the water back, and is measured at right angles to the direc-
tion of motion of the water. Fig. 40 shows a profile of a
propeller blade taken at right angles to the shaft, while Fig.
41 shows a profile in the direction of the shaft. The area of
Fig. 41 multiplied by the number of blades would be the pro-
jected ai*ea of the propeller surface, while the developed
area would be the entire driving surface of the blades, usu-
ally called the blade surface.

The accepted form of blade surface to give the best results
is what is known as a warped surface. In someone direc-
tion on such a surface, straight lines can be drawn, but to the
eye, and by the application of a straightedge in any other
direction, it has a slightly dished or concave surface.

49. Slip of Propeller. — The apparent slip of a pro-
peller is the difference between the actual speed of the boat

§19

ENGINE AUXILIARIES

with reference to some fixed point on shore and the
speed at which the propeller would cut ahead, or travel
through the water, without resistance or slip.

The apparent slip, often called simply the slip^ is gener-
ally used in determining the action of the propeller. To
test a propeller on a boat, in order to determine its apparent
slip, its action should be observed when running the boat over
a measured course. This ^ay be done before or after the
pitch of the propeller is measured. The number of revolu-
tions of the engine should be recorded carefully, with the
length of time to cover the course. The boat should be
driven at a maximum speed, and if there is a known current
its velocity should be added when running against the curr
rent and subtracted when running with the current The
engine should then be slowed a little, and the revolutions
and time again recorded. These results should be figured
out carefully and tabulated somewhat as follows:

Course If Miles, or 7,260 Feet, Pitch of Propeller,

40 Inches

Revolu-
tions Per
Minute

Mean

Time

Actual Speed

Per Hour

Miles

Speed Per Hour
with No Slip
Miles

Slip
Percent

Min,

. Sec.

302

9- 556

11.439

278

9.167

10.530

240

8.000

9.091

204

6.827

7.727

180

6.037

6.818

The speed per hour can be computed by using the formula

;r = 60

(1)

in which a = time, in minutes, elapsed in traveling over the

course;
b = length of course, in miles;
X = rate of speed, in miles per hour.

54 AUTOMOBILE AND MARINE §

Thus, at 180 revolutions per minute, the speed in t
table, taking 13f minutes as the time to travel If mil<

would be ;r = 60 X zrA- = 6.037 miles per hour. KnowioK — S

IdJ

the pitch of the propeller, and the number of revolutio

per minute, the speed with no slip can be calculated by

formula

in which s = speed with no slip, in miles per hour;
n = number of revolutions per minute;
/ = pitch of propeller, in inches.

Example. — If the pitch of a propeller is 40 inches, and the number
revolutions per minute is 180, what is the speed with no slip?

Solution. — Applying formula 2:

180 X40 ^Q,Q . , .

s = ^ vl^ =6.818 mi. per hr. Ans.

The difference between the cutting ahead and the actu -^^■-^
speed is the slip, which in the example just given ^ ^
0. 818 — 6. 037 = . 781 mile, the rate of slip being the percenta^
.781 is of 6.818, which is 11.45 per cent The table shoi
that the slip increases with the speed of the engin<
natural result.

•

60. Increasing the blade surface of a propeller, leaviscrB-.^

the pitch and diameter the same, will reduce the eflfectL^^^^^
power of the engine and the percentage of slip; whi^^
decreasing the blade surface will increase the effective po^^^^^
by reducing the resistance, the slip being increased. Incre^a*-^"
ing the pitch or reducing the diameter of the propeller sm^^^^
increase the percentage of slip, but will also increase tl^e
effective power of the engine ; while reducing the pitch <^^
increasing the diameter of the propeller will reduce tb^
percentage of slip and decrease the effective power c>i
the engine.

Whether the speed of the boat will be helped by decrease
ing the blade surface and increasing the pitch, or vice ver*^

§ 19 ENGINE AUXILIARIES 65

can be determined only by trial, there being so many com-
binations of conditions that the best designers of propellers
frequently fail to obtain satisfactory results. By mak-
ing an analysis of the propeller, pitch, blade surface, etc.,
and studying the results of tests, it is frequently possible to
improve the speed of the boat by change of propellers, but
such a change should not be made by guess. Propeller
experiments are quite likely to be expensive.

When the pitch of a propeller is increasing or decreasing
it is difficult to measure, and it is customary in that case to
measure the pitch at a point one-third of the distance from
the end of the blade to the center of the shaft, and the pitch
thus measured is usually referred to as the mean pitch.
Or, the pitch may be measured at several equidistant points
each side of the center of the blade, and a mean of the meas-
urements taken as the mean pitch.

61« Beverslng Propellers. — In some cases it is found
expedient to use reversing or feathering blade propellers.
The blades may be feathered or the angle at which the driv-
ing surface strikes the water may be so changed that the
water is driven ahead instead of astern, without reversing •
the direction of rotation of the propeller shaft. Midway
between the ahead and the astern posi tion is a neutral zone
in which an equal power in both directions is exerted, with
no effect on the boat in either direction. There is usually
but one position of the blades that approximates true pitch,
and on this account there is a considerable amount of power
lost in their use, unless they are very carefully designed and
specially built.

A sleeve sliding on the shaft and connected to the blades
themselves, often within an enlarged hub, or attached to it
and operated by means of a lever or hand wheel inside the
hull, is sometimes used to control the position of the blades.
Such an arrangement is shown in Fig. 42 {a). The propeller
blades are shown at a, a, the outside stuffingbox at b, the
stem bearing at r, the sliding sleeve at ^/, the inside stuffing-
box at ey and the reversing lever at /. One of the blades

AUTOMOBILE AND MARINE

§19

separate from the device is shown in Fig. 42 (^), with the
pivot g that fits into the hub and about which the blade tumsi
The pin h of this blade fits into the slot i in the fork y* Fig.
42 (a) and {c\ The fork is attached to the sleeve d^ and as

PlO. 42

the sleeve is moved forwards or backwards the fork moves
the pins so as to cause both blades to turn about their
pivots. The propeller shaft is shown at k. The sliding
sleeve revolves with the shaft, but is free to be moved along
the shaft by the lever/.

POWER-GAS PRODUCERS

coif STBUCTION OF PRODUCERS

PRESSURE AND SUCTION TYPES

1, It is sometimes desirable or necessary to operate a gas
engine independently of a central gas plant. In such cases, it
is possible to produce the fuel gas required to run the gas
engine at a lower cost than when using either illuminating gas
or the more volatile grades of liquid fuel, such as gasoline
and distillate of petroleum. This has led to the gradual
development of an apparatus known as a pcwer-gas
producer, which is practically a small gas plant located
near the engine, to which it furnishes gas. The process of
making gas from coal, coke, or charcoal by means of such a
producer is a simple one. The gas-generating and purifying
devices are of such size as to be readily installed in power
plants using gas engines and operating under ordinary
conditions. They occupy but a small amount of space, and
the attendance, even in a fairly large plant, requires only a
portion of the time of one man.

S* Classification of Producers. — Modem gas produ-
cers may be divided into two general classes namely,
pressure producers and suction producers.

In pressure producers, the gas is generatea oy forcing
a blast oi steam from a boiler, or of moistened air from a
blower, through a bed of incandescent fuel. The gas is puri-
fied in a scrubber, stored in a gas holder of suitable capacity,

C^pyrigktedby International Textbook Company. Entered at Stationer* s Hally London.

§'.20

2 POWER-GAS PRODUCERS g 20

and supplied to the engine at a pressure of from 2 to 3
ounces. Pressure producers are generally used in large
power plants and where more than one engine is supplied
from the producer. They are also adapted to the use of dif-
ferent kinds of fuel.

In suction producers, air and water vapor at atmospheric
pressure are drawn through the incandescent fuel by the inhal-
ing or suction action of the engine, due to the partial vacuum
produced in the engine cylinder during the suction stroke of
the piston. The gas so generated is cooled and purified in
the same manner as in the pressure producer. The volume
of ga? in a suction producer is thus never in excess of that
required by the engine, and consequently it is not necessary
to provide a holder, the gas being drawn directly from the
producer to the engine cylinder. The amount of gas genera-
ted depends on the force of the suction or the number of
inhalations transmitted from the engine cylinder to the pro-
ducer. The engine governor controls either the volume of
the charges .or the number of charges required to operate
the engine under any load.

3, Power Gas. — The pressure process of manufacturing
producer gas for power purposes has not been materially
changed since its introduction 20 years ago by Dowson, in
England. Producer gas had previously been used for heating
purposes, in which case it was desirable to keep the tempera-
ture of the gas as high as possible before being burned. In
generating power gas the conditions and requirements are
materially different, the desired object being the transforma-
tion of the heat in the coal into the chemical energy of cold
gas, because it is only in a thoroughly cooled condition that
gas can be used efficiently in engines.

In the pressure process of generating gas for heating pur-
poses, the dry air is heated before being introduced into the
producer ; in the generation of power gas, on the other hand,
the object is to reduce the temperature of the gas as much as
possible by admitting to the producer a certain amount of air
and water vapor, so that, when the mixture is brought in

4 POWER-GAS PRODUCERS § SO

contact with the burning fuel, hydrogen will be liberat^r<i.
With even this cooling effect, however, the gases leave
producer at a temperature that is generally above 900° F.

The process of manufacturing power gas consists prin
pally in heating some form of fuel to a very high tempe
ture in a vessel from which the atmosphere can be excluded.
The vessel in which the heating takes place is called the
producer, or grenerator. The vessel in which water is
heated, in order to supply moisture to the air that is admitted
to the producer, is called the evaporator, or boiler.

After the gas is made in the producer, it is purified and
used directly, or else stored in suitable tanks. The several
steps in the process of gas generation will be treated in detail
in connection with the various types of producers.

PKESSUHE GAS PRODUCERS

4, One of the first types of pressure producers, as intro-
duced by Dowson in England, and of which several plants
have been installed in America, is illustrated in Fig. 1. Tb^
boiler a generates steam at from 60 to 75 pounds pressure,
the steam being conveyed to the injector b through the pipe ^-
In the injector, the steam is discharged through a small no^*
zle, and the issuing current draws with it a certain amoun*
of air from the casing d surrounding the pipe r, through
which the hot gases leave the producer /i Thus the injector
serves merely to deliver a mingled stream of air and steam
to the ash-pit ^ of the producer, beneath the grate.

The producer consists of a cylindrical shell made of steel
plates and lined with a highly refractory grade .of firebrick.
A hopper //, which is closed toward the atmosphere by 4
removable lid /, and against the interior of the producer bf
means of the bell j\ conducts fuel to the producer while in
o|XTation. The bell being tight against its seat, the lid can
be removed and the hopper filled with fuel. After closing
the hopper, the bell is allowed to drop, permitting the fuel to
enter the firepot of the producer, where it descends to the

POWER-GAS PRODUCERS 5

e and is constuned, the ashes and clinkers beingf removed
ugh the door k.

• The steam entering the producer is decomposed into
fen and hydrogen while passing through the incandes-

fueL This oxygen, together with that which is in the
mixed with the steam, unites with the carbon of the

to form carbon dioxide and carbon monoxide. These
IS mix with those produced from the fuel by the
: and pass upwards through the port / and the

I e. The pipe e is provided with fittings having remov-
handhole covers, for the purpose of giving easy access

ase it becomes necessary to clean the pipe. The gas is
t forced through the water box w, where it is washed and
t of the impurities removed ; it then enters the scrub-
«, which is filled with coke to within a few inches of the
et pipe o near the top. As the gas rises in the scrubber,
met by a descending shower of water distributed over
entire area by me^ns of the sprinkler/. The water cools
gas and carries away some of the impurities, leaving a

II portion deposited on the coke. The coke is placed in
scrubber with the larger pieces at the bottom, the sizes
lually diminishing toward the top, and need not be
5wed for a period of from 1 to 2 years, according to

quality of the fuel used in the producer and the
►unt of tarry matter contained in the fueL After the
5 becomes clogged, the scrubber is emptied and fresh
5 provided.

ny dust or other impurities that the gas may contain
r leaving the scrubber is removed while passing through

purifier box q — ^sometimes called a sawdust purifier —
ch consists of a square box with a removable top and con-
s a series of wooden gratings r, over which are spread
rs of sawdust or similar material. The gas is now ready
>e stored in a holder, not shown in the illustration, from
A it is supplied to the engine in the same way as illumi-
ng gas> t>ut of course in larger quantity, proportionate to
Dwer heating or calorific power.

6 POWER-GAS PRODUCERS §$2C

6, The gas generated when the producer is first starti
is of very poor quality and unfit to be stored in the hold<
It is therefore permitted to escape into the atmosphe
through the smoke and waste-gas pipe j, until, by a test ma«
at the tube /, the gas shows that it is of the proper quality,
burning with a bright blue flame. As soon as the quality 1»^ ^
come up to the desired standard, the valve u in the wa^t
pipe is closed, and the gas is allowed to pass on its vr ^
through the scrubber to the holder. The overflow from L^la
water box m passes through the water seal v^ which pena-il
the water to flow to the sewer without allowing any gas t
escape.

It will be seen, by an examination of Fig. 1, that all pii:>ej
between the producer and the holder are provided with fit-
tings having handholes and covers, so that the pipes can
easily be cleaned as occasion may require. It must be under-
stood that, especially when using the poorer grades of coal,
some of the impurities contained in the gas will adhere to
the walls of the pipes, and in time sufficient quantities may
accumulate to interfere with the free flow of the gas from
the producer to the engine.

The pressure of the gas at the point where the injector b
connects to the ash-pit of the producer is about 8 inches of
water. This pressure gradually diminishes on account of the
resistance that the gas encounters during its passage from
the producer to the holder. Measured by a water gauge, the
pressure in the pipe e between the producer and the water
box is equal to about 6 inches; after leaving the scrubber,
the pressure is 4 inches, and before entering the holder it is
2 inches.

STTCnON GAS PRODITCKBS

7* Comparison of Suction and Pressure Producers.

A comparison of the pressure producer with the suction produ-
cer discloses the fact that the chemical changes brought about
in both types are practically the same. The difference between
the two types is therefore not in the nature of the product

8 POWER-GAS PRODUCERS §20

but in the manner in which the gas is transmitted from the
gas apparatus to the engine. The processes of generating
and purifying the gas are the same in both cases; but in
the pressure producer a pressure above that of the atmos-
phere is maintained by a forced draft, either from a low-
pressure steam boiler or from a blower; while in the suction
producer the pressure in any part of the apparatus or its
connections is never higher than that of the atmosphere. The
draft in the suction producer is furnished by the engine pis-
tori during the suction stroke while the inlet valves are open,
and the vacuum created in the cylinder causes the gas from
all parts of the producer apparatus to flow toward the
engine.

The difference in pressure between the two systems is
practically 8 inches of water; so that, in the suction pro-
ducer, the pressure of the gas as it leaves the scrubber is
about 6 inches of water below atmospheric pressure instead
of 2 inches above, as in the case of the pressure producer.
The relative difference in pressure in the various parts of
the apparatus is the same in both systems, and the order of
the operations of the process is necessarily alike in both
cases. The suction type of producer does not require a
large gas holder, a small cast-iron or sheet-metal tank being
used instead. This tank is but slightly larger than the cus-
tomary gas bag or pressure regulator used in connection
with engines using illuminating gas.

8. Supply of Air and Moisture. — ^A suction gas pro-
ducer of small capacity, in which the evaporator for supply-
ing the necessary moisture to the air is mounted directly
above the producer shell, is shown in Fig. 2. The apparatus
consists of the producer a with a cast-iron shell; the hand-
operated blower ^, for reviving the fire, after a shut-down
over night; the evaporator c\ the hopper d\ the water
trap e\ the water-seal box f\ the scrubber g\ and the gas
tank or reservoir h. At each suction stroke of the engine,
air is drawn into the top of the evaporator c^ through the
elbow /, which is open to the atmosphere. The evaporator

§20 POWER-GAS PRODUCERS 9

is filled with water from a branch pipe taken from the main
supply pipe and kept at a constant level by an overflow
pipe, not shown in the illustration, that carries any surplus
supply to the ash-pit j. The water in the evaporator is
heated to about 170° F. by radiation from the burning fuel
and by the hot gases that leave the producer through the
port)6.

The air passing over the surface of the hot water absorbs
a quantity of vapor, the amount depending on the tempera-
ture of the water; so that the quantity of the water vapor
admitted with the air through the pipe / to the space below
the grate is greater when the fire is hot than when it is low.
The fire is hottest, of course, when the engine is carrying a
heavy load. Under heavy load, not only does the increase
in the amount of vapor enrich the quality of the gas gen-
crated, but also the moistened air has a correspondingly
S^reater cooling effect on the grate and tends to keep the fire
at a proper degree of intensity.

9. After entering the ash-pit below the grate, the mix-
ture of air and steam is drawn upwards through the hot bed
0^ fuel, where the steam is decomiposed into hydrogen and
oxygen, and the formation of carbon monoxide takes place.
After transferring a portion of its heat' to the water in the
evaporator, the gas leaves the producer through the port ky
passes through the water trap e^ and enters the scrubber at
the bottom. The water trap has two pipe connections to
the water-seal box/, the lower pipe being provided with a
valve m. While the plant is in operation, this valve is open
^d the water that accumulates in the bottom of the scrub-
her flows through the lower connection to the seal box /and
thence through an overflow funnel n to the sewer. When
the plant is shut down, the valve ;// should be closed, thus
fusing the water in the trap e to rise well above the lower
®n<J of the partition wall o. This closes the gas connection
'^tween the producer and the engine. Any excess of water
^^n flowing to the seal box passes through the upper pipe
attached to the trap e and thence to the sewer.

10 POWER-GAS PRODUCERS §20

1(). Passajuro of Giis Throug:li Scrubber. — While the
gas is rising" through the coarse coke in the scrubber gy it is
met by a descending stream of cold water which is distrib-
uted evenly over the area of the scrubber by means of the
sprinkler / attached to the top cover-plate. In this man-
ner, the gas, from which some of its impurities have been
removed while passing through the trap t\ is now cooled and
washed sufficiently to be delivered to the gas tank // in such
condition that it contains no tarry or dusty substances to
interfere with the successful running of the engine. When
semianthracite or similar fuels containing higher percent-
ages of tarry matter than pure anthracite or charcoal are
used, it is necessary to add a sawdust purifier similar to that
used in connection with the pressure producer shown in
Fig. 1.

!!• Supplying: tlie Fuel. — The fuel is supplied to the
producer shown in Fig. 2 through the charging device
mounted above the hopper rf", which consists of the funnel q
and a smooth hollow ball r that can be turned on its ground
seat by the hand lever s. The ball has an opening at the
top, so that it may be fill^ with coal through the funnel,
after which it is turned over by a quick movement of the
hand lever, bringing the opening in the ball in communica-
tion with the coal space in the hopper d. As soon as the
ball has thus been emptied of its contents, it is turned back
and the operations of filling and emptying are repeated until
the hopper is filled to the desired height. When not in use
for filling the producer, the ball is held tightly on its seat
with screws and hand nuts. The quick turning of the ball
leaves but a small fraction of a second during which the
hopper is open to the atmosphere, and practically no air is
admitted to the producer at that point.

12. Heiuovinjo: Aslies and Clinkers. — The removal of

clinkers that form in the fire space of the producer is facih-
tatcd by poke holes, with which the hopper is provided, that
permit the fire to be stirred from above with suitable poking

§20 POWER-GAS PRODUCERS 11

rodts. The clinkers descend to the grate and are removed
through the two fire-doors /, /, on opposite sides of the cast-
iron shell of the producer, while the ashes accumulating in
th^ pit below the grate are drawn out through the ash-
dooT //.

A3. Starting: tlie Producer. — The hand-operated
bloi^-er b serves to supply the blast necessary to start up the
fire after the plant has been shut down for any length of
time, say over night. During such a temporar}' shut-down,
the process of gas making is practically stopped, except for
the small amount of gas generated by the natural draft
caused by the flue pipe v being kept open to the atmosphere
^y opening the flue valve w. While reviving the fire, the
valve «/, as well as the valve x in the vent pipe j/, is kept
openuntil the gas escaping at the test tubes z^ z — one of which
is placed in the pipes between the producer and the scrub-
ber, and the other near the inlet to the engine— is of such
quality as to bum with a bright blue flame. As soon as
this is the case, the valve te/, and the valves in z and z are
closed and the engine is started in the usual manner. To
secure prompt starting, it is found advisable to keep the
valve in the vent pipe y open to the atmosphere until a few
explosions have taken place in the engine cylinder, and then
close it.

I-ARGE-CAPACITY PRODUCKR

14. A suction producer of larger capacity than the one
shown in Fig. 2 and Equipped with a separate evaporator is
shown in Fig. 3. Instead of the castriron body shown in
^^%' 2 in connection with the smaller type, the producer a
consists of a shell built of steel plate and lined with fire-
brick; but the hopper d and the coal-feeding device r are
made of cast iron, and are essentially of the same construc-
tion as in the smaller producer. Instead of a hand blower,
a belt-driven pressure blower b furnishes the draft for
starting.

yt_

§20 POWER-GAS PRODUCERS -13

The essential difference between the larger and the
smaller plant is that the evaporator for heating the water in
the smaller plant forms a part of the generator, while in the
large plant it is a separate piece of apparatus and is con-
nected to the generator by pipes. In the case of the larger,
the evaporator consists of a cylindrical casting c with a hood e
having a vertical dividing wall in the center, so that the air
entering through the pipe /will be forced over the surface
of the hot water in the evaporator before it passes to the
ash-pit of the producer through the pipe g. Between the
evaporator cylinder c and the hood is clamped a plate // car-
rying a number of vertical tubes / that are kept full of
water, the level of the water being kept constant by an over-
flow pipey slightly above the upper surface of the plate //.
The hot gases leave the producer through the pipe k^ and
pass downwards and then upwards in the evaporator, being
guided by the vertical partition /, and finally pass on to the
scrubber m. In this manner, the water in the tubes is kept
at the desired temperature, so that the required amount of
vapor is taken up by the air while passing through the
hood e to the ash-pit of the producer.

In order to be able to control the amount of moist and dry
air used, a regulating plate n is provided in the air pipe, by
means of which the air-supply pipe can be opened to any
desired extent to the atmosphere in the producer room, thus
admitting cool air that has not come in contact with the hot
water. The three-way valve o serves to shut off the air
connection to the evaporator when the fire is being revived
by the blast from the blower. As soon as the gas has
become of good quality, the blower is stopped and the
three-way valve set so as to admit air in the regular way
through the pipe g.

GOMBnnSD PRODUCEU AXD EVAPORATOR

Iff, Another suction gas producer of somewhat different
design is shown in Fig. 4. The producer itself consists of a
l^liiftdricsl steel shell lined with firebrick and fitted with a

enter the producer. Frotn tbe Isiipper, ihe fori i

iolo the fiiv-»pi»c« thioQi^h the feeding tobe ^ sumnrndcd I

the c\-»pot»tvir A in which the necessary steam i* generat ed

I 20 POWER-GAS PRODL'CKRS J5

at atmospheric pressure by the heat of the fire and of the
gases when leaving the producer.

16. The ashes are removed from the ash-pit g through
the door h. A series of poke holes i distributed over the
top of the producer permits rods to be inserted for the pur-

pose of poking the fire and removing clinkers from the walls
of the lining. Dry air is admitted to the ash-pit through
the supply pipe /, while moist air, which is saturated with
steam from the evaporator, is supplied to the ash-pit through
pipes k, air boxes /, and nipples in. TJie air enters the top
of the evaporator through the valve n. The proportionate

16 POWERGAS PRODUCERS § 20

amonnts of dry and moist air can be regulated as desired by
opening or closing the valves n and o. The band-operated
blower / is used for starting or reviving the fire. Kand-
holes q in the top of the evaporator are provided for the
purpose of removing any sediment that may accumulate in
the bottom of the evaporator. The water supply to the
evaporator is automatically regulated by the float r that con-
trols a valve in the water box s. The water rising in the
box raises the float and closes the valve, while the lowering
of the float opens the water valve. The gas passes from the
producer to the scrubber through the pipe /, which is con-
nected to the top of the producer.

17, An outside view of a producer of this type, con-
nected to its scrubber, is shown in Fig. 5. The producer is
shown at a and the scrubber at b. The hopper c with the
filling device d is located aver the producer and is readily
accessible by the stairs and the platform around the top of
the producer. The fittings ^, ^', admit the air to the evap-
orator, and the handles /are connected to the covers of the
openings through which the fire is poked. The handle^ is
provided for the purpose of rocking the grate, and the door
h gives access to the fire. The vent pipe is shown at i and
the main gas pipe at/, connected to the scrubber at ky with
the water trap / extending below the scrubber. There are
a number of manholes m, /«, on the side of the scrubber,
to permit easy access to the interior. The water connections
are shown at ;/, and the gas outlet from the scrubber at o.
Producer plants of this style are made in units of from 15 to
250 horsepower, and are very compact and convenient.

DOVrX-DRAPT PRODTTCKR

18. A gas-producer plant in which the draft is furnished
by an exhaust fan operated by a small motor, drawing the
<^as from one scrubber and forcing it through another into a
gasholder, is shown in Fig. G. This apparatus consists of two
similar generators a and b, an evaporator r, a wet scrubber^

§ 2o POWER-GAS PRODUCERS 17

axhaust fan ^, a dry scrubber /, and the gas holder g. The
► generators are of the doivn-draft type^ which is consid-
^ especially adapted to the use of fuels containing tarry
tter, such as bituminous coal, wood, etc. The gas and
substances produced by the fresh fuel in the upper
ion of the producer, pass down through the incandes-
t fuel bed, where they are heated to a very high tempera-
^^^^e, and a gas free from tar is thus formed.

"ZIQ, The generators consist of cylindrical steel shells
^^^ed with firebrick and provided with firebrick arches h that
^^'pport the fuel beds. Openings i, /', at the tops of the gen-
^"^ators, serve for charging fuel, and for the admission of
^T, and the usual fire and ash doors are provided for clean-
^"Jig the arches and for the removal of ashes. Steam jets/, /',
One in each generator, are supplied from the boiler c. The
toiler is of the vertical type, and is connected by brick-lined
flues ife, k\ to the bottoms of the generators, the passages
being controlled by water-cooled valves ///, m\ The hot
gases leave the generators at the bottom, pass through the
evaporator, and impart a portion of their heat to the water
contained in the space around the tubes. The steam pro-
duced is directed into the top of the fire by the jets/*,/.
The hot gases pass up through the tubes to the outlet pipe.

20« The wet scrubber «/, consisting of a cylindrical steel
shell, contains a number of trays filled with coke moistened
by the water sprays n and o, A purifier p filled with excelsior
is attached to the top of the scrubber. The gas- inlet pipe /
at the bottom of the scrubber is attached to a horizontal per-
forated diaphragm q submerged in water, so that the gas
must pass through the water before rising in the scrubber.

21. The fan or exhauster c maintains the necessary vac-
uum required to furnish the proper amount of draft and give
sufficient pressure to deliver the gas to the holder. The
motor that drives the exhauster is connected to the gas
holder in such a way that the speed is automatically

18 POWER-GAS PRODUCERS §20

regulated, by the movement of the holder, to conform to the
demand for gas. When the holder is full, the speed of the
exhauster is decreased ; while in descending, as the gas is
consumed, the motor speed is increased, creating a corre-
spondingly stronger draft and a greater production of gas.
The direction in which the gas flows after being delivered by
the exhauster is controlled by the valves r and s. The valve
r is connected to the waste-gas pipe and is kept open to the
atmosphere while the fire is being started or revived. As
soon as the gas becomes of the proper quality, the valve r is
closed and the valve s opened, so that the gas can pass to the
dry scrubber f and holder g,

32. The dry scrubber contains two trays /, /', filled with
excelsior, sawdust, or shavings. A horizontal partition u
divides the scrubber into an upper and a lower chamber.
The pipe connections to these chambers are fitted with
valves, so that either the upper or the lower chamber can be
connected to or shut off from the gas supply, thus making it
easy to remove the trays, for the purpose of cleaning and
recharging, without interrupting the operation of the appa-
ratus. From the dry scrubber, the gas passes to the gas
holder g, which consists of a stationary water tank t% filled
with water, and an inverted movable tank it', which fits
inside the water tank. The gas enters the holder through
the pipe x^ whose upper end is slightly above the level of
the water in the tank v.

As the amount of gas in the holder increases, the movable
tank iu rises, giving additional space for the gas between
the water surface and the top of the tank iv. When the vol-
ume of gas in the holder decreases, the tank %v descends.
The pressure of the gas in the holder is thus kept constant.
The lower edi^e of the tank iv is always submerged, forming
a water seal that effectually prevents the escape of gas,

23. While the a]^paratus is in operation, the generators
a and b are open at the top, so that the attendant can observe
the condition of the fire and add fresh fuel where needed.

80 POWER-GAS PRODUCERS 19

le condition of the fire may be regulated by occasionally
ssing a jet of steam up through one and down through
3 other generator, by means of auxiliary pipes ^jj^', cou-
nted to the bottoms of the generators. The steam is
roduced alternately in each generator; and the top door i
1 the valve m of one generator are closed and steam is
>\vn into the ash-pit through the pipe j^. This operation
ises an up draft through one generator and a down draft
•ough the other.

Should wood be used as fuel, the generators are filled
th coke to a height of 3 or 4 feet above the arches //,
i wood in lengths of 2 or 3 feet — or of ordinary cordwood
e, 4 feet in length, if the generators are large — is placed
top of the coke. The wood is ignited, and the gas is
Livered to the scrubbers and holders in the usual manner.
> steam is admitted at the . top, however, as the wood
ually contains a sufficient amount of moisture to render
- gas of proper quality.

M^\Jf AGEMENT OF PRODIJCERS

PREPAKIXG PRODUCERS FOR OPERATION

54, Foundations for Producers. — The foundations for
►duccrs should be built in accordance with plans furnished

the makers. As a rule, it is necessary to set both the
Kjucer and the scrubber on slightly elevated platforms of
ck or concrete, to raise the apparatus to a level where it
1 be easily accessible to the operator and to bring the
*ious parts of the system in proper alinemcnt, so that the
>es and fittings furnished by the maker will connect as
onded. Special cases may occur where the conditions are
'h as to require some deviation from standard plans, and
such instances the manufacturer of the apparatus should

consulted and his recommendations and suggestions
lowed.

168—14

20 POWER-GAS PRODUCERS § 20

Upon the arrival of the machinery at the place where it is
to be installed, it is well to examine all the parts for defects
and to clean thoroughly all vessels, castings, tanks, etc., of
any packing material, dirt, or sand left accidentally in the
castings at the foundry. This suggestion applies to the
various parts of the gas producer, as well as to the pipes and
fittings.

IJNTNG THE PRODUCEB

26. Firebrick. — Where the firebrick lining consists of
special shapes, as is the case in most suction producers as
well as in small sizes of pressure producers, the bricks
should be carefully examined and any that are damaged,
broken, or cracked, rejected. As a rule, a few extra bricks
of each size are furnished, to allow for possible shortage of
material that may be caused by the accidental breaking of
some of the bricks while in transit

Before attempting to place the lining in the producer
shell, it is advisable to set the lining up on a floor or any
other level place outside the shell, and to make sure that
the various bricks fit without leaving excessively large
spaces or crevices. If necessary, the bricks should be
ground to each other, so as to remove any irregularities in
shape and to reduce crevices to not more than -J- inch at the
joints. It is also necessary to see that the size of the lining
is in accordance with the producer shell, that the circle
formed by the bricks is not larger in diameter than the
shell, and that, when making proper allowance for mortar,
the total height of the lining will be such as to bring it up
to the desired level inside of the producer.

26, Mortar. — After leveling the producer on its foun-
dation, the laying of the firebrick lining may proceed. In
preparing the mortar, care must be taken to use a grade of
fireclay that will withstand tlic heat of the fire. As a rule,
the manufacturer of the apparatus supplies the clay to cor-
respond with the material used in making the bricks. The
mortar is made -of fireclay and water, and should be of about

§ 20 POWER-GAS PRODUCERS 21

the consistency of the cement mortar used in laying bricks
for foundations. It is of great importance to work the mor-
tar thoroughly, so as to make it smooth and of uniform com-
position. There should not be more than a layer of | inch
in thickness between the various courses of bricks.

Any openings or fissures that show on the inner surface of
the lining, and that are therefore exposed to the heat of the
fire, must be filled with a smooth pulp made of fireclay, asbes-
tos, and water, of about the consistency of ordinary putty.
This pulp will withstand the action of the hot fire, while
mortar made of fireclay and water alone would crumble and
fall away in a short time. The pulp must be rammed tightly
into all fissures, and the whole inside of the lining smoothed
up if the irregular shape of the bricks requires it.

It is of the utmost importance to have the inner surface
of the lining as smooth as possible, so as to prevent clinkers
from adhering to the wall. It also prevents the poking
tools from catching in the joints of the brickwork and dam-
aging the lining, when trying to remove the clinkers.

37. Filling: Between lilnlngr and Shell.— The lining
is usually insulated from the shell of the producer by having
the space between the bricks and the metal filled with a
suitable material. Sand has been used, and if of the proper
g^ade it will answer the purpose very well. The best sand
for this purpose is molders* sand that has been used in the
foundry for making iron castings. A much better material,
however, although slightly more expensive, is mineral wool^
which can be obtained at low cost almost anywhere. Min-
eral wool is made by subjecting molten slag to a strong
air blast, the cooled product having a porous, fluffy appear-
ance resembling cotton. Sand has the disadvantage of being
liable to run' out of any cracks that accidentally develop in
the brick lining. This of course would necessitate taking
enough of the producer apart to be able to replace the sand
lost in this way. Mineral wool will stay in place as long
as the lining lasts, and the freedom from danger of a
shut-down, such as might occur where sand is used, will

22 POWER-GAS PRODUCERS § 20

more than pay for the additional first cost of the mineral
wool

28, Before filling the space between the lining and the
shell, all the fissures around the fire-doors and the annular
space around the bricks should be filled first, with a pulp
made of fireclay, asbestos, and water, the same as that used
for smoothing up the inner surface of the lining. Next the
space should be filled with this pulp to a depth of several
inches and then the mineral wool used up to within 2 or 3
inches of the top of the lining. The remainder of the space
is then filled with pulp like that used in the bottom. This
makes the whole space tight against leakage and keeps the
insulating material in place, as the pulp will become hard
after the fire is started in the producer. When putting in
the mineral wool, it should be packed tight with a suitable
tool as soon as a small quantity has been applied, and the
ramming should be continued until the desired space is
filled, so as to form a homogeneous mass of insulating^
material. After the lining and filling are completed, the top
of the producer may be put in place.

nLLTNG THE SCRUBBER

29. After the' scrubber has been placed in position, le v^ —
eled up, and properly alined with the producer, the cole. ^
that is generally used as a purifying agent should be plac^ <i
in the scrubber. In doing this, care should be taken not "^lo
break or grind the coke, and thus make dust and small piec^^s
that will pack the coke tight and interfere with the flow of
the gas through the scrubber. When the scrubber is to ^M)e
entirely filled, the pieces of coke should be selected caref xx ^ly
as to size and the larger pieces placed in the bottom, the s^S^ze
gradually diminishing toward the top. The lower portm on
of the scrubber may contain pieces of about 4 inches in s£ ^e,
while nothing smaller than 1^ inches should be used at * lie
top. To avoid breaking the coke in handling, it should be
let down into the scrubber by means of a basket, a second ^

§20 POWER-GAS PRODUCERS 23

rope being fastened to the bottom of the basket, so that it

can be tilted and emptied when it has reached the bottom.

Another equally good method is for a man to stand on a

'^oard in the bottom of the scrubber and distribute the coke

^ter it has been lowered into it The contents of the scrub-

^r should reach up to within about 6 inches of the lower

^€re of the gas-outlet pipe connected at the top.

Any coke that may accidentally fall through the scrubber
^^te should be removed from the space below the grate be-
for-^ the scrubber doors are finally closed. If this is not
^t^ended to, some of the small particles of coke may be
^^^ed into the pipe connections and cause trouble by
^^^^ging them.

PIPE CONNECTIONS

30. In making the pipe connections between the various
I^^rts of the apparatus, sharp bends should always be avoided,
^ they produce unnecessary friction and thus retard the flow
^f the gas in the pipes. Retarded flow is especially objec-
tionable in connection with suction gas producers, and it is
^f considerable importance to provide long-sweep elbows
^ther than the ordinary cast-iron fittings. As producer gas
Always contains some impurities before it passes through the
Scrubber, it becomes necessary to clean the connecting pipes
^nd fittings regularly. After leaving the scrubber, the gas
^^ay still contain a small amount of dust or tarry matter that
"Will accumulate in the pipe connections. To enable the
X^ipes to be cleaned without taking them apart, the fittings
Should be provided with handholes and removable covers, for
"^be purpose of making their interiors accessible.

31 • The flue valve in the waste pipe that branches off
Crom the connection between the producer and scrubber is
xnore liable to become clogged by impurities than any valve
\)eyond the scrubber. This valve must therefore be arranged
so that it can be easily taken apart to be cleaned and lubri-
cated. It is desirable to provide a drip pipe and valve below

U POWER-GAS PRODUCERS § 20

the flue valve, for draining any water that may collect in the
smoke pipe either from the atmosphere or by condensation.

32. In order to have the smoke pipe constructed so as to
give a good draft, which is essential in keeping the fire alive
over night when the plant is shut down, it should be run in
the shortest and most direct way possible. The general
arrangement of the smoke pipe is of course governed by
local conditions, but it should not have any sharp turns nor
nm horizontally for any length. If it is necessary to have a
short length of horizontal pipe before the stack turns verti-
cally, there should be a drain provided at the bottom of the
elbow where the turn is made. The vertical length of the
smoke pipe must be sufficient to insure a strong draft, and
if there are any buildings in the vicinity the top of the pipe
should be carried several feet above the top of such build-
ings. If this is not done, the gases that will escape from the
stack while the fire is being started might cause annoyance
to tenants of such buildings.

If the smoke pipe is led into an old chimney that has been
used before, it should be carried up through the entire length
until it reaches the open air. This is of special importance
if any stoves are connected to the same chimney, because, if
a fire was lighted in one of the stoves, gas issuing from the
smoke pipe into the chimney might be ignited and result in
a violent explosion.

TESTING FOR LEAKS

33. Whether the producer is of the pressure or of the
suction type, it is equally important that the apparatus itself
as well as all pipe connections be made absolutely tight.
Neglect in this respect would cause leakage of gas in the
pressure producer and result in danger to the health and life
of persons in the producer room. While this danger does not
exist in the suction producer, owing to the fact that the
pressure in this type of apparatus is always below that of the
atmosphere, small leaks would cause air to be drawn into
the apparatus from the outside and result in weakening the

§20 POWER-GAS PRODUCERS 25

gas and in rendering it ot such quality as to prevent good
results from its use in the engine. If the leak is very seri-
ous, the gas would become so poor as to cut down the power
considerably and eventually stop the engine.

34. Before attemptmg to make gas, all the joints and

connections should be tested. A safe method of doing this

is to generate pressure in the apparatus by closing the valves

and operating the blower provided for reviving the fire. By

attaching a small pressure gauge at a convenient point before

the pressure is raised, and letting the apparatus stand for a

while afterwards it can be determined whether there are any

leaks. If the gauge shows a fall in pressure, it is necessary

to investigate and locate the place at which the leak occurs.

£ach part of the apparatus can be shut off from the others, by

means of the valves provided, and the point of leakage can

t.1ias be accurately determined. When the leak is located,

it should be stopped.

The parts most likely to become leaky are the coal-charg-
ing device and the fire and ash-doors. In handling the fuel
snd the ashes, it is Almost impossible to prevent impurities
:f rom settling upon the surfaces of the doors and charging
apparatus. It is therefore advisable to always clean these
surfaces after fuel has been admitted or ashes or clinkers
lave been removed.

OPERATION OF SUCTION PBODUCKHS

STABTIXO THE PRODUCEB

35* After it has been ascertained that everything about
the apparatus is in good working order in accordance with
the directions, the producer is ready to be put in operation.
To start the fire, the generator should be filled, to a height
of about 18 inches above the grate, with dry, non-resinous
wood, or with charcoal. A small quantity of cotton waste
soaked in oil and placed upon the grate under the wood will
aid in starting the fire. If 'fat pine — sometimes called fitfcA

26 POWER-GAS PRODUCERS § 20

pine^ on account of the amount of pitch it contains — or a
similar wood is used to ignite the coal, a smaller quantity
will be sufficient. In case the wood contains much pitch,
no gas should be permitted to pass into the scrubber until-
the wood has been entirely consumed.

36, Before lighting the fire, the evaporator should be
filled, and a small amount of water allowed to overflow into
the ash-pit. The water-seal box should also be filled, and
the water supply turned on in the scrubber as soon as the
fire is started. The valve in the smoke pipe must be
opened and the top of the hopper closed before lighting the
fire. After igniting the wood, the ash-doors, fire-doors, and
the pipe suppljdng moist air from the evaporator to the bot-
tom of the producer must be closed. The connection
between the blower and the producer is then opened, and the
blower started, turning it either by hand or by power, as
the case may be, unt^l the wood is burning freely. Follow
this by filling in- about 8 to 12 inches of coal and continue
blowing for a while until the fire is burning brightly. After
this, the producer and hopper should be practically filled to
the top with coal. Continue the operation of the blower
until the gas at the test pipe between the producer and the
scrubber bums steadily with a bright blue flame. Then
close the communication between the blower and the pro-
ducer, and quickly remove any ashes or clinkers that may
have been deposited upon the grate. While doing so, the
fire-doors through which these ashes are. removed should be
kept open no longer than is absolutely necessary.

37. Now reestablish communication between the blower^
and the producer and again operate the blower for a shorts
time until the gas, by burning steadily with a blue flame,^
proves that it is of the proper quality. As soon as this i^
the case, all the apparatus, including the pipe connections- -
between the scrubber and the engine, should be filled witlt
gas, thus replacing the air with which they were previously -
filled. This is accomplished by closing the flue valve an*-

§ 20 POWER-GAS PRODUCERS . 27

also the vent pipe that branches off from the gas-supply
pipe near the engine. The vent pipe is provided for the pur-
pose of making sure that the whole pipe system up to the
engine is filled with gas of good quality.

It will generally require from 10 to 16 minutes from the time
of starting the fire until all the apparatus is filled with gas.
There should also be a test pipe provided in the gas-supply
pipe near the throttle valve on the engine. As soon as a
trial at this point shows the gas to be of good quality, the
plant is ready for operation and the engine can be started in
the usual way.

FIRING THE PRODUCER

38. In order to secure steady and efficient service of the
plant, it is necessary for the operator to accustom himself to
performing the series of operations carefully and always in
the same regular rotation. Experience has shown that the
following method of procedure gives the best results: If
the fire requires looking after, the first thing to do is to fill
in fresh fuel practically up to the top of the hopper, so as to
replace any coal that has been consumed during the run.
The second operation should be the poking from the top.
This is done for the purpose of removing any clinkers that
may have begun to adhere to the walls of the brick lining,
^nd also for the purpose of preventing the formation of hol-
low spaces in the hot bed of fuel known as bridging,

39. The fire should be poked at regular intervals, as
determined by the quality of the fuel used and the experi-
ence the operator may gain while running the producer
Tinder the conditions of load in each particular case. It will
:iiot do to neglect removing the clinkers, because, if they
should be allowed to accumulate on the walls of the brick
lining in any considerable quantity, it would be impossible
to remove them while the apparatus is in operation, and
consequently it would be necessary to shut down the plant
temporarily and interrupt the service.

88 POWER-GAS PRODUCERS §90

40. The third operation should be the removal of the
ashes from the ash-pit under the grate. This is generally
done with a bent scraper. The fourth and last operation
consists of poking and removing clinkers from the grate
through the fire-doors. With a stationary gratey a bent
poker is used for this purpose, afte^ the clinkers have been
loosened with a straight bar of suitable shape and length.
This removal of clinkers through the fire-door should be
done quickly ; in order to prevent an excessive amount of air
from entering the producer, open one door at a time just
enough to permit of the removal of clinkers. If the pro-
ducer is provided with two doors on opposite sides, close one
door while the other is kept open. The whole operation of
removing clinkers from the grate should not require more
than 20 to 30 seconds.

These operations apply, of course, only to stationai}'
grates. In producers provided with shaking or rotating
grates, the cleaning is done by rocking or turning them by
means of the hand levers or cranks provided for this
purpose.

STOPPING THB PRODUCBR PLANT

41. The engine is stopped as usual by simply closing
the gas valve and disconnecting the battery. At the same
time, in order to stop the producer plant in the proper
manner, the valve in the vent pipe must be opened at once,
so as to provide an escape for the gases that continue to
form in the producer for a short time after the engine has
been stopped. Next, the hopper of the producer should be
filled with fuel and the flue valve in the smoke pipe opened.
As soon as this valve is opened, the valve in the vent pipe
near the engine can be closed. The water supply to the
scrubber and producer should then be shut off and the
valves adjusted that regulate the level of the water in the
seal and water trap between the scrubber and producer, so
that the gas will be shut off from the scrubber. Experience
will show just how far to open the air supply that regu-
lates the draft necessary' to keep the fire alive over night

g 20 POWER-GAS PRODUCERS 29

wifhout unnecessary waste of fuel while the plant is shut
down.

The ashes and clinkers should be removed from the pro-
ducer, and the fire and ash-doors kept closed. Should it
become necessary to remove large quantities of clinkers, it
will be found easier to do this immediately after stopping
the plant and while the fuel is still incandescent. It is best,
in such cases, to draw the fire completely and to remove the
clinkers from above after opening the cover of the hopper.

RESTARTING THE PRODUCER

43. To start the plant after it has been shut down over
night, it is necessary only to remove from the grate any ashes
or clinkers that may be deposited during the night, and to
operate the blower until the gas bums with a bright blue flame
at the test tube between the scrubber and the engine.
Then open the vent and the scrubber valves, see that the
hopper is closed tightly, and start the engine in the usual
way.

CLEANING THE PIPE CONNECTIONS

43. It is always advisable to attend to the cleaning of
pipes and fittings in the day time, so that it will not be
necessary to use a light, as a flame brought too close to the
apparatus might ignite the gas. It is also advisable, as a
matter of precaution, to have more than one person present
w^hile the cleaning is being done, so as to guard against
accidents.

The building or room in which the producer is located
should be well provided with ventilators, so that any escap-
ing gas will be quickly carried away. The gas is very pois-
onous, and, if it accumulates, is liable to render the work-
men unconscious and may cause deatli. Hence special care
should be taken to avoid breathing it. Under ordinary con-
ditions it ^411 be found sufficient to have the pipe? examined
and cleaned once in 3 months.

30 POWER-GAS PRODUCERS § 20

44, The contents of the scrubber mav last for a veai*or
more before they require renewing. If it becomes neces-
sary to clean the scrubber, the whole producer must, of
course, be put out of commission. The manholes of the
scrubber should first be opened, so that any gas contained in
the scrubber may escape. 1 1 may require about 1 hour or more
for the gas to stop, after which the coke may be removed.
Any sediment that may accumulate in the bottom of the
water-seal box, at the bottom of the scrubber, should be
cleaned out at least once every other day.

OPERATIOX OF PRESSURE PRODUCERS

46, The directions already given for the care of produ-
cers apply especially to suction producers, but they are almost
equally applicable to pressure producers, especially in regard
to the firebrick lining, pipe connections, etc But the
arrangement of the fuel bed is different in the pressure type
from that used in the suction producer. Instead of having
on top of the incandescent fuel a large amount of coal that
is not burning, the height of the fuel bed is limited to from
2^ to 3 feet above the ashes when using anthracite, and from
3^ to 4^ feet when using bituminous coal. This will require
a pressure for the air blast of from 3 to 4 inches of water.

If the blast is too strong or the coal too fine, the fuel will
burn too fast near the walls, and it will be necessary either
to reduce the blast or to use a coarser grade of coal. To
keep the fuel bed reasonably solid and avoid the formation
of bridges or honeycombing, a certain amount of poking, or
barring, must be done, the frequency of which depends on the
character of the fuel or the rate at which the producer is work-
in^. A little experience and careful observation will enable
the operator to determine just how often the fire needs atten-
tion, so as to keep it in the best condition for steady service.

When Slopping a ])ressure producer, no imbumt coal
should be left on top of the fuel bed; the top layer shoi^dbe
incandescent. The blast should be decreased just before

§ 20 POWER-GAS PRODUCERS 31

stopping, the poke-hole caps removed, and the escaping gas
lighted at the open holes. Then the blast may be shut
off entirely. Air will be drawn into the producer by the
receding flame, so that the gas in the producer will bum
quietly without any violent puff.

BLAST-FXJRNACE GAS FOR GAS ENGINES

QUAIilTY OF GAS FROM BliAST FURNACES

46, The use of blast-furnace gas for gas engines is of
recent origin, and cannot yet be said to have passed much
beyond the experimental stage. The blast furnace is used
for melting iron ores and producing pig iron. The furnace
varies from 40 to 100 feet in height, and from 12 to 26 feet
in diameter. The fuel employed is coke, and the air blast
used to promote combustion produces a temperature suffi-
ciently high to melt the ore, and has a pressure of from 6 to
15 pounds per square inch above that of the atmosphere.
The amount of gas that passes from the blast furnace is
about 150,000 cubic feet per ton of pig iron produced. In
order that the iron may not combine with oxygen pass-
ing through the furnace, the amount of air admitted is insuffi-
cient to complete the combustion of the fuel, and hence the
gas passing out of the furnace contains a large amount of
carbon monoxide. Blast-furnace gas, however, is not as rich
in combustible matter as is producer gas, but it contains
enough combustible matter to furnish considerable power
when used in gas engines of suitable design. The average
composition of blast-furnace gas is about as follows:

Gas Per Cent.

Carbon dioxide, CO^ 08

Carbon monoxide, CO 30

Hydrogen, H 02

Nitrogen, N 60

Total 100

32 POWER-GAS PRODUCERS §20

There is usually present some hydrocarbon that affects these
percentages to a slight extent. The thermal value of blast-
furnace gas varies from about 90 to 100 British thermal units
•per cubic foot, depending on the percentage of carbon mon-
oxide present. The fact that the gas is low in hydrogen and
rather high in carbon monoxide makes it desirable for gas
engines especially designed for its use. It has been found,
in practice, that the gas from the blast furnace will furnish
about 50 horsepower continuously for each ton of pig iron
produced in 24 hours.

47. One of the principal difficulties to be contended with
in connection with the use of blast-furnace gas in gas engines
is the large amount of gritty dust that the gas contains. This
necessitates very careful and thorough cleaning of the gas
before it is admitted to the engine cylinder. The gas should
be as nearly free from solid matter as it is possible to make
it by any cleaning method now in use. When the gas comes
from the blast furnace, it usually contains from 4 to 7 grains,
and may contain as much as 12 grains of dust per cubic foot ; its
temperature is also high, ranging from about 500® to 1,000® F.
or more. The amount of dust contained has been reduced
by some of the best modem cleaning processes to as low as
.01 grain per cubic foot, and even less, which is said to be
less than the dust contained in ordinary air.

When the gas from the blast furnace is not sufficiently
cleaned before it goes into the gas engine, the dust collects
on the inner surface of the cylinder, and, as the piston moves
to and fro, the dust is ground between the piston and cyl-
inder, thus causing excessive heating and perhaps cutting of
the surfaces. Sometimes, the dust collects in the combustion
chamber or valves, becomes incandescent from the heat of
the explosions, and causes prcignition.

48, To get the greatest efficiency from the combustion
of the gas, it should be cool and dry as well as clean. The
high temperature of the gas causes it to evaporate some of
the water used in thecleanin«4- process and to carry with it a

8 20 POWER-GAS PRODUCERS 33

large percentage of moisture. This moisture is detrimental
to the combustion, but is a great aid in getting rid of the
dust. The particles of dust are moistened by it, and
adhere more readily to any surface with which they come in
contact But the moisture must be removed before the gas
enters the engine. This is done by cooling the gas, thus
causing the moisture to condense. As it condenses, it falls by
gravity to the bottom of the apparatus, carrying with it a
considerable amount of dust.

The gas is forced through the cleaning apparatus by a
steam jet or by some form of fan or blower.

CJIiEANIXG BliAST-FURNACE GAS

49. In the earliest blast-furnace gas-engine plants, the
gas was cleaned by about the same process used in a pro-
ducer plant. It was found, however, that this process did
not dean blast-furnace gas sufficiently for use in gas engines.
Hence the cleaning process was extended by adding scrub-
bers and rotary washers to the apparatus already in use. In
some cases, the rotary washer was simply a fan with pro-
vision for spraying water into the gas; while in others, it
took the form of an enclosed rotating drum or series of disks
partly submerged in water. The gas being forced through
the washer came in contact with the large wetted surface to
which the particles of dust adhered, and as the surface
revolved into the water the dust was washed away. A still
later development is represented by the centrifugal cleaner,
in which the gas is carried around inside of a casing by a
revolving drum with projecting vanes, the speed being such
that the centrifugal force throws the dust against the casing,
from which it is washed by a spray of water.

60. Cleaning: Plant With Rotary Washer. — The gas

IS carried in flues or pipes from the blast furnace to the
cleaning ' apparatus and engines. It is taken from the
flue leading downwards from the top of the furnace — known
as the down-comer — and conducted to a main, which may

34 POWER-GAS PRODUCERS § 20

also receive the gas from other furnaces. It then passies
through a washing process that takes out the larger particles
of dust and grit. Next, the gas goes through a long pipe or
series of pipes that reduce its temperature and take out con-
siderable dust and moisture. In the first washing process,
the gas takes up considerable moisture, and the dust, becom-
ing moist, adheres readily to the surfaces with which i^
comes in contact. From the long pipes, the gas may pa^
through a rotary washer consisting of a fan or a drum wit^
vanes on its circumference with a spray of water injects ^
into it. The whirling motion given the gas as it pass^^
through the fan throws the dust against the casing, to whicr^
it adheres and from which it is washed into a water outlet If ^
the injection water. From the fan or rotary washer, theg^-^
may pass through other scrubbers or washers similar to th-
coke scrubber or sawdust cleaner described in connectio
with the producer-gas plant. Sometimes, two scrubbers
cleaners are used, in which case the gas passes first through
coke scrubber and then through a sawdust cleaner forremoV^ '
ing the finer particles^f dust. From the last cleaning process*
the gas is taken in many plants to a gas holder of considec
able size, where the remaining moisture in the form of vapc^^
is condensed by cooling and settles with the remaining dust

From the gas holder, the gas is conducted directly to th»^
engine cylinder. The gas holder serves the double purpo^;^
of a cleaner and a regulator or equalizer of the pressure <::>f
the gas delivered to the engine. The pressure of the g^s
in the holder will usually vary from 1 to 2 or more ounces
per square inch above atmospheric pressure.

When the rotary washers are properly designed axad
installed, the scrubbers between the cleaner and gas holder
and the long pipes may be dispensed with, thus reducing the
size, first cost, and operating expenses of the cleaner plant.
Furthermore, the gas is cleaned much better than in the
cleaners used on producer- gas plants.

51. Centrifugal Cleaning: Plant. — In the cleaning
plants that have given the best results with European

POWER-GAS PRODUCERS

blast-furnace gas, a rotary or a centrifugal washer fonns
the principal part. In some plants, large, slowly tam-
ing washers are used; while in others, small and rapidly
turning centrifugal washers are employed. In the first, ilie
cleaning is done by bringing the gas in contact with a lung
revolving surface that dips into the water at every revolu-
tion, thus washing off the collected dirt and wetting the sur-
face. In the second, the gas is driven by centrifugal force
against the sides of the casing and the dirt washed out with
a spray of water.

A centrifugal plant for cleaning blast-furnace gas is shown
in Fig. 7. Before the gas reaches the centrifugal cleaner, it
is passed through a dry stationary dust catcher, or cleaner, '
where larger particles of dust are removed. The stationary
cleaner may be siinply a large closed drum in which the
velocity is low and the dust is allowed to settle out by grav-
ity; or it may be a smaller drum and contain deflectors for
changing the direction of motion of the current of gas. From
the dust catcher, the gas passes down through the pipe a to
the centrifugal cleaner t>. The interna! dnim of the centrif-
ugal cleaner revolves at about 850 revolutions per miniite,
thus producing sufficient velocity in the gas to cause the por-
ticlesof dust and dirt to ily outwards against the casing, tinder
the influence of the centrifugal force. The gas usuallycanies
from 1 to 3 grains of dust per cubic foot as it leaves the dn"
cleaner, and the centrifugal cleaner reduces this amount lo
about .01 grain per cubic foot before the gas leaves. The
moisture in the gas, however, is increased, and for this reason
the use of a dn.'er or dry filter is found advisable. The centrif-
ugal cleaner b is driven by a motor c, the gas leaves by the oai-
lel J, and passes around the baffle plate in e, where someef
the moisture is precipitated. The gas then passes through the
pipe _/* and valve ^ to the main A, from which it can be dnrum
off at different points, as desired. The valve i opens to tiK
dry filter/, which contains trays carrying slats covered willi
mineral wool or other diying substance, through which the
gas passes in the direction shown by the arrows. The dry
filter is divided into two compartments by the partition k.

POWER-GAS PRODUCERS

the g:as passing through one tray of mineral wool in each
conapartineiit, leaving it comparatively dry. The valve i
regulates the opening to the main tn, which conducts the gas
to a holder or directly to the gas engines.

5S. The Centrifugal Cleaner. — ^A larger view of the
centrifugal cleaner is shown in Fig. 8. The blast-furnace
gas enters the cleaner through the opening shown at a.
The casing b remains stationary, while the drum c is keyed
to the shaft d, with which it revolves. The small vanes e
are arranged in the form of a spiral around the drum c, so

that the gas must pass through a long passage or be thrown
against the outer casing as the drum revolves. The gas
leaves the washer through the outlet f, and passes to a dry
filter, as previously described. Water is sprayed against
the revolving drum through the inlets g, and is carried
around by the vanes of the drum with sufficient speed to
keep the casing wet and furnish water for washing ofE the
dust as fast as it collects. The dirty water passes out
through the water leg h to a drain.

The gas that enters the cleaner is still hot, sometimes
having a temperature as high as 300° or even 400° F, It
consequently vaporizes some of the water when it first
comes in contact with the wet surfaces of the centrifugal

38 POWER-GAS PRODUCERS § 20

cleaner. This vapor mingles with the dust in the gas, and
the centrifugal force throws the vapor and dust outwards,
causing them to come in contact with the outer casing, to
which they adhere. A wire screen is located inside the
casing where the injection water enters, so that the water is
at once broken up into fine particles, offering more surface
to the dust and being more easily vaporized. The tempera-
ture of the gas is also reduced by the water, the amount
varying from 60° to 260° F., depending on the temperature of
the blast-furnace gas, the temperature of the water, and the
efficiency of the cleaner. It is customary to keep the water
stored in elevated tanks, and feed it to the washers by grav-
ity and to discharge it into clearing ponds. The dust and
dirt are allowed to settle out of the water, which is then
pumped through cooling coils back to an elevated tank,
from which it again flows to the cleaner by gravity. The
water is thus cooled and cleaned, and hence can be used
over and over again with the addition of a small amount of
fresh water.

MANAGEMENT OF AUTOMOBILE

ENGINES

CAKE AKD ADJUSTMENT

INSPECTION, AND I^OCATION OF FAUIiTS

1. The owner or chauffeur who for the first time takes
charge of an automobile must, especially if the machine is a
new one or of an unfamiliar type, make a searching exam-
ination of the condition of the automobile tefore it will be
prudent or even safe for him to attempt its operation. This
examination should not be limited to the engine and its
accessories, but should include all parts of the car. In the
following articles, attention is directed to the parts of the
engine that should receive careful attention.

3, In the first place, a general survey of the engine
should be made — particularly if it is of an unfamiliar type — •
special attention being given to the location and mode of
action of each individual part included in the valve mechan-
ism, the ignition mechanism, and the governor, pump, radi-
ator, carbureter, etc. Attention should be given to the steps
necessary to be taken in order to expose, for examination, the
working parts of the engine, such as, the two- to-one gears (if
thesie are enclosed), the pump, the cams, the igniters (if these
are of the contact variety), the magneto (if any), and the
interior of the crank-case, so far as this can be reached

Qfpyri^kiedby Jnternationai Textbook Company. Entered at Stationer f Hall^ London,

$21

2 MANAGEMENT OF AUTOMOBILE ENGINES § 21

without dismantling the engine. On completing this pre-
liminary investigation, the condition of the various
should be examined in detail.

3, The float valve of the carbureter should be tested
leaks by opening the valve between it and the tank an
looking for gasoline drip. If gasoline escapes, it may siir^
ply be because the float is set too high, so that it does
close the needle valve before gasoline issues from the spra^
nozzle. Or, it may be that the valve itself leaks.

At this stage, it is well to assume that the float is prop^

erly adjusted, and to begin by shutting off the main gaso^^^
line valve, and then unscrewing the washout plug below th
needle valve. It may be found that dirt, waste, or a splin-^
ter of wood has got past the strainer, through which, pre-
sumably, the gasoline passes on its way to the float, and is
lodged in the needle-valve opening. It may be of advan-
tage to open the top of the float chamber, which can usually
be done without disturbing other parts, and take out the
float and needle valve. A little gasoline washed down
through the needle- valve orifice will then generally carry away
any dirt that may have clung to the valve when the plug
was unscrewed. If the gasoline still drips when the parts
are reassembled, the mixing chamber should be opened and
the top of the spray nozzle examined to see if gasoline is^
escaping from it. An electric light should be used in mak-
ing an examination of the carbureter, as, with any othe
illuminant, a fire might be started. The portable electri
flashlights sold everywhere at a moderate price answer th
purpose very well.

4. If gasoline is escaping from the spray noxzle, th
needle valve of the float may be carefully ground in, b
placing between the valve and its seat a paste made of po
dered grinding material and oil or water, using for this pu
pose either very fine sand, or, preferably, pumice or rotte
stone. The method of regrinding valves will be explainer"
more fully in Troubles and Remedies, Emory should n
be used, as it will embed itself in the brass valve or seju

§ 21 MANAGEMENT OF AUTOMOBILE ENGINES 3

A little of the sand or pumice should be mixed with oil to
make a paste. The mixture is applied to the needle point,
which is then rotated by quarter turns in its seat with slight
pressure, taking care to keep the stem as nearly vertical as
possible and frequently adding fresh paste.

If this does not stop the leaking, it is likely that the float
is too high ; but, unless the gasoline escapes very rapidly, it
is better not to disturb the float until attention has been
given to other more important details. The car, however,
should not be left standing with the main gasoline valve
open, for the dripping gasoline may catch fire from the
lamps, from a stray spark in the ignition circuit or at the
timer, or from a match accidentally dropped near the valve.

The manner of adjusting the carbureter should be noted,
but the adjustment should not be disturbed unnecessarily,
as it is often hard to get the right mixture after this has
been done.

6, Next to making sure that there are no gasoline leaks,
the most important thing is to see that no bearings are too
tight or have seized, owing to lack of oil or the bending of
the shaft or connecting-rods. The compression relief cocks
should be opened and the shaft turned over slowly by hand.
The shaft should move with entire freedom, a little more
easily at the beginning and end of the piston stroke than at
raid-stroke, because of the slower movement of the piston
at the ends of the stroke, but with no binding or sticking at
any point. If the shaft turns hard, the car should be
taken to the repair shop, since probably either the bearings
or the pistons are cut, or the shaft or rods are sprung out of
true, as, for .example, from having struck a loose nut or
other obstruction in the crank-case, or from preignitions in
the cylinders. Fortunately, serious trouble of this sort does
not often occur.

At the outset, it is well to locate all loose bearings, since
these require more lubrication than properly fitted bearings.
If they are very loose, there is a strong likelihood that they
have been cut, in which case they ought to be opened,

4 MANAGEMENT OF AUTOMOBILE ENGJNESgSl

scraped, and refitted at the earliest possible moment. 0[
the main-shaft bearings, that next to the flywheel is the
most likely to be loose. If the engine is vertical, 3 jack
may be put under the flywheel and the jack-lever worked
gently up and down to disclose looseness, if any, in this
bearing.

G. To expose the crankpin bearings of a vertical motor,
it is sometimes necessary to take down the. bottom half of
the crank-case, which is generally attached to the upper
half by capscrews or studs, and which simply serves the
purpose of an oil pan. Under this arrangement, the shaft
bearings are usually supported from the upper half of the
crank-case, which is itself supported on the frame of the
car. Nevertheless, it is advisable, when slackening the
screws or the nuts on the studs, to find out whether or not
they are carrying the weight of the crank-shaft. This caa
be done by slackening all the screws several turns, and then
pushing upwards against the oil pan with the hand to see
how much pressure is necessary to lift the pan off the
screws. If the shaft is found to be resting on them, it will
be better not to take it down at once, unless it is evident
that the main-shaft bearings themselves need attention.
Generally, if the shaft is supported by the bottom half of
the case, the crankpin bearings can be reached from hand-
holes located in the bottom or sides of the crank-case.

The crankpin bearings can be tested for lightness by set-
ting the engine at mid-stroke and oscillating the flywheel
very gently back and forth while the fingers of one hand att
resting on the edge of the crankpin bearing. A sligbt
looseness may be allowed, provided the lubrication is suffi-
cient, and there is no cause to suspect that the bearings have
been cut, The amount of permissible looseness \v^U depend
to a great extent on the particular engine and the speed at
which it is to run. A vertical four-cylinder engine running
at moderate speed will bear as much as .002 inch of lost
motion on the crankpins, but if the same engine is run at a
high speed this will be too much.

§ 21 MANAGEMENT OF AUTOMOBILE ENGINES 5

7. The main-shaft bearings will bear less lost motion
than the crankpins, and if one bearing is worn more than
another, as is likely to be the case, it will result in one-sided
wear of the crankpin bearings, due to the settling of the
shaft. The main-shaft bearings ought not to have more
than .001 inch of play before being taken up, but more than
this is often found.

A double-opposed horizontal engine will, sooner than any
other type, develop a pounding sound, generally called a
poundy at the main-shaft bearings, owing to the fact that the
explosions occur alternately in opposite cylinders, and there
is nothing to keep the shaft against one or the other side of
its bearings.

8. In addition to the inspection tor loose bearings, the
principal nuts and screws should be tested to see that they
are tight, and if any cotter pins are missing from bolts,
studs, or slotted nuts, they should be supplied at once. The
bolts on the crankpin bearings should also be examined for
tightness, and to see that cotter pins are supplied.

9. If the inlet valves are automatic, see that they work
freely in their guides, that they do not leak, and that their
springs are not too weak. If there is more than one cylin-
der, the inlet-valve springs must be alike in tension. If the
valves stick, they may be freed by squirting a spoonful of
gasoline on them. If they leak, they should be ground in,
as described later.

The openings of the valves should be determined to some
extent by their diameters. Valves up to 2 inches in outside
diameter generally lift about \ inch, and slightly more than
this if they are larger. The keys through the valve stems
should be examined to see that they are not on the point of
breaking.

The tensions of the valve spring on similar valves of the
same engine should be equal; their equality may be tested
by pressing the ends of the valve stems together while the
valves are held by their cages, as shown in Fig. 1. The
valves should begin to open with about the same pressure.

' (1 MANAGEMENT OF AUTOMOBILE ENGINES§iI

I and should also reach full opening with equal pressures. 1/
I one spring is weaker than the others, it may be taken ofl
and stretched gently. Too great a lift makes the valvi:
sluggish in closing, and permits a portion of the fresh
charge to be forced backwards through the valve at the
beginning of the compression stroke; this prevents the
engine from attaiDin^
its maximum speed.
When the valve open
ing is too great, 't
may be reduced by
sltppmg a washer
o\er the stem. For
this purpose, BOinc
sort of a spring
washer is preferable,
but not essential A
makeshift of soft wire
will not do, as the hammering of the \alve will soon break
it, and a bit tit wire may make a great deal of trouble by
getting into the cyHnders.

10. The user should satisfy himself regarding the Inbri-
' cation of every part of the engine. Every oil pipe shoulil
be traced, and every oil cup and oil hole located and the
purpose of each ascertained. Oil pipes leading from the
automatic lubricator should be disconnected close to the beflT-
ings or cylinders, and the lubricator worked by hand to see
that it is feeding properly. Generally, this can be done bj'
working the pump plungers tip and down to the extent of
the lost motion on the pump eccentric. If this cannot be
done, the delivery of oil may be watched after the engine
has been started.

If an oil pipe is clogged it should be disconnected close to
the lubricator; and if no oil comes from the lubricator at that
point the cause of stoppage should be located. The trouble
will probably be fonnd to be caused by dirt or waste under the
check-valves of the pump. If oil comes from the lubricator

§21 MANAGEMENT OF AUTOMOBILE ENGINES 7

when the pipe is disconnected, the latter is stopped up, and
can be cleaned by running a wire through it. Generally, how-
ever, any obstruction of this sort will travel to the end of the
pipe and lodge in the check- valve, if there is one at that
point, so that the check-valve should be unscrewed and
examined.

11. The manner in which oil is supplied to the crank-
pins should be ascertained, since these are sometimes fed
simply by internal splash and sometimes by centrifugal ring
oilers and oil passages drilled through the cranks. If inter-
nal splash is relied on, the user should see that the crank-
case contains enough clean oil to allow the connecting-rod
caps to dip into it about ^ inch at the lower end of their
stroke.

If the car has not been used for a considerable time, the oil
in the crank-case, oil cups, and reservoir is likely to be stiff
and gummy. ^ If this is the case, the oil should be drawn off,
and a moderate quantity of kerosene used to make sure that
the oiling system generally is thoroughly clean. Before
starting the motor, a liberal supply of fresh oil should be
provided, as the kerosene will cut away the old oil wherever
it reaches, and the pistons, cylinders, and bearings might
become cut before the fresh oil can reach them from the res-
ervoir. When oil has not been cleaned out in this manner, it
is a good precaution, on general principles, to put a pint or a
quart of fresh oil into the crank-case. If, however, on start-
ing the motor it is seen that a considerable quantity of white
smoke is being produced, the crank-case has evidently too
much oil, and a portion should be drawn off.

13. The ignition circuit should next be gone over. This
should be done with the switch closed and the safety plug —
that is, a plug the removal of which will break the circuit
— if one is used, inserted in the switch or coil, the gasoline
shut off, and the compression relief cocks (if any) open. The
positions of the lever controlling the spark for early and late
ignition should be ascertained by a careful examination of
the timer, and the lever should be set for a late, or retarded,

8 MANAGEMENT OF AUTOMOBILE ENGINES §21

spark, as a precaution in case of any accidental explosion in
the cylinders. The engine should be turned over slowly,
and the sound of each of the vibrators on the coils noted
The sound should be clear and regular, and fairly high with-
out being tinny. If necessary, the contact screws, or the
tension screws, if there are any, of the vibrator springs
should be adjusted until the vibrators sound alike.

13. The timer should be examined to see that the con-
tact segments are not badly pitted by the spark at the leav-
ing edge. If they are pitted, or if the fiber or hard rubber
adjacent to them is roughened by the sparking, the timer
should be cleaned upas well as possible with a piece of sand-
paper or a file, and the first opportunity taken to true it in
a lathe. If the timer is rough, the contact roller pr fingers
will jump and give very erratic contact when the motor is
running fast.

The spark plugs should be unscrewed and their condition
examined. It is not necessary to take them apart unless
they need cleaning, or unless it is discovered that the porce-
lain is broken, which will be evident by a looseness of the
outer end. If the porcelain is broken and there are spare
porcelains at hand, the bushing may be unscrewed and a
new porcelain and gasket inserted. Usually, it is impracti-
cable to use the old gasket a second time, as the bushing has
to be screwed down so tight as to endanger the porcelain.
The bushings should be set down sufficiently to prevent leak-
age past the porcelain, but no more.

14. The gap between the spark points should not be
greater than ^V inch for the best possible spark. The points
should be presented directly to each other, and should be filed
t:ue and square. The spark will not be so intense if it jumps
between needle points. If necessary, the porcelains should
be cleaned. To do this properly, it is generally necessary to
take the ping apart. The porcelains are cleaned with a cloth
or brush wet in gasoline. If the carbon deposit is very hard,
it may be loosened with fine emery cloth and the cleaning
finished with gasoline and a cloth. In assembling the plug,

§ 21 MANAGEMENT OF AUTOMOBILE ENGINES 9

care should be taken that the spark points are restored in
their correct relation to each other.

15, The battery may be weak and may have to be
reoharged or replaced. If dry cells are used, it is likely that
some of them are weaker than others. The only way to
determine this is to use a battery tester, which is a small pocket
ammeter through which the cell may be momentarily short-
cix^cuited. The battery as a whole may be tested by discon-
necting one of the secondary cables from the spark plug and
noting the length of the spark in the open air. The spark
sliculd be at least f inch in length — \ inch is better. The
coil should not be worked with the detached cable held so far
from the motor that no spark can jump, as this is liable
to tax the insulation of the secondary winding.

16. Having gone over the engine, it may be started, to

determine whether the ignition and carbureter adjustments

have been made properly. Set the throttle so that the motor

does not run excessively fast, and listen to the sounds it

^akes. Any knocking sound should at once be traced to its

source and eliminated. The sound may be due to a loose

mud-guard or something of the sort on the car, which of

course does not affect the engine. Or it may be found in

the loose coupling between the clutch and the gear-shaft, but

this coupling is intended to be loose, and will give no trouble.

Any knock due to a loose bearing or loose bolt, however, should

at once receive attention. It may be found that the motor

will run light — that is, without driving the car — and with the

throttle nearly closed without developing a knock, but may

^ock badly when under load. This subject is taken up in

T'^oubles and Remedies,

17. The sound of the impulses should be listened to; also
t^e sound of the exhaust at the muffler. If the engine has
several cylinders, the impulses should be equally timed and
should take place with equal force. If, with the spark some-
what retarded, the impulse is more energetic in one cylinder
than another, which may generally be told by the muffled

10 MANAGExMENT OF AUTOMOBILE ENGINES §il

sound of the explosion, it is either because ignition takes
place too early in the cylinder, or because a deposit of car-
bon in the combustion chamber ignites the charge in its own
vicinity immediately after the spark, so that the charge is
burning from two points at once and consequently more rap-
idly than it should. Actual preignition, that is, too-early
ignition, due to carbon deposit, seldom occurs when the
engine is running light, but may occur when the car is run-
ning. If early ignition in one cylinder is due to faulty
timer adjustment, the difficulty may be corrected in some
one of several ways, according to the construction of the
timer. Sometimes the adjustment must b6 made by filing
the contact segments. This should, however, be attempted
only as a last resort, after it has become evident that the
trouble is not caused by heated carbon in the cylinder, or
causes that can be corrected in some other way.

18. If the inlet valves are automatic, they are likely to
work unequally when the motor is running light with the
throttle nearly closed. Under these conditions, the most
careful equalizing of the springs will not prevent one or two
cylinders from assuming most of the work, because the
force available to open the valves is so small. Often, an
engine will run on one or two cylinders for some time in
this manner, and then for no apparent reason some other
cylinder will start working, and the first will stop. As soon
as the throttle is opened, all the cylinders begin to work
alike.

19. When the engine is running light, a late ignition in
one cylinder will show itself by a louder exhaust from that
particular cylinder, owing to the slower combustion of the
charg^e, and consequent higher pressure when the exhaust
valve opens. The remedy for late ignition is practically the
same as for early ignition, any adjustment of the timer being,
of course, in the opposite direction.

20. A quick method of testing the spark timing is as
follows: Shut off the gasoline, retard the spark as far as

§ 21 MANAGEMENT OF AUTOMOBILE ENGINES 11

possible, and open the compression relief cocks. Turn the
crank slowly by hand, letting the air escape through the
cocks so that the compression will not cause the pistons to
run ahead, which would take up the slack between the
crank-shaft and the timer, thus giving a false result. Note
the position when the vibrator begins to buzz, and mark the
rim with chalk or otherwise. Now turn the crank, always
forwards^ until the next vibrator begins to work, and note
the flywheel position again. If the engine has four cylin-
ders, or two vertical cylinders with opposite cranks, the new
position should be exactly one-half a turn from the old. If
the engine has two opposed cylinders, or two vertical cylin-
ders, with the cranks together, the flywheel should have
made exactly a complete revolution. If there are three
cylinders, the marks on the flywheel should be one-third of
fhe rim circumference apart. Many modem cars have the
flywheel rims already marked to indicate the top and bottom
positions of the cranks, and these marks may be used, as the
spark should occur exactly at the outer or upper dead cen-
ter when fully retarded.

In case the spark timing is found to be very irregular, it
is best to attend to it at once, and in any case irregular tim-
ing should not be neglected, as it involves a considerable
loss of power. -

21. While the motor is running, note whether the cool-
ing water is circulating properly. The motor should be able
to run indefinitely with the throttle just open and the spark
about one-half advanced, without the radiator heating up
excessively, provided that the latter has a fan to assist its
cooling. If, on taking the car out on the road, it is found
that the radiator is persistently overheated, the cause of
such overheating should be investigated. The trouble may
be found to be due to a clogged pipe, dirt or oil on the inside
or the outside of the radiator, a defective pump, clogged
radiator tubes, etc. Before starting, one should always see
that there is plenty of water in the radiator, as a deficient
supply will cause overheating.

J 2 MANAGEMENT OF AUTOMOBILE ENGINES § 52 A

CABE OF THE ENGINES

GENERAL INSTRUCTIOirS

22. The ordinary care of a good automobile engin
when everything is working well, is a very simple matte- rx",
and comprises hardly anything more than due attention -to
lubrication, occasional testing of the batteries, with rechar^^:-
ing or replacement as required, and seeing that the radiat<i3r
or water tank is kept full. All the oil supply to the lubricr ^t-
tor and oil cups should be strained, though; as the lubx^-
cator itself is probably fitted with a strainer, no additioim .s.1
attention at this point is likely to be required heyowr^d.
occasionally taking out and cleaning the strainer. If amny
dirt, bits of wood, or fibers of waste get past the strains r,
they are liable to make trouble if the oil is fed throu^r^
any kind of a check-valve or needle valve. Waste is p^x"-
ticularly troublesome in this respect, as it shreds and a f^^vv^
fibers of it may very easily get into the oil without bei icig
noticed.

23 If the engine is fed from a mechanical oiler, the oil
pipes should occasionally be disconnected near the engine ^
and the engine nm or the pump worked by any other avail-
able means, to determine if the oil is feeding properly-
Most indiWdual pump oilers are operated by eccen trios,
which work against stop-screws attached to the plungex"S,
atui the strx^ke of the plungers is adjusted by turning the^se
scrvws to allow mor^ or less lost motion between them axad
the iXXXMUrics, The operator should learn, by experimen t-
iti): with the |\irtioular kind of oil he uses, what is the le^^^^
stroke for oaoh p\i:r*p that will lubricate the engine proper 1 J
If thotx^ is arv i^Tcat diiTervnce between the strokes tl^'^^
vu tovir.ir.ov:, it is prx^lv^V.e that there is leakage^ either in ttie
•jWvkinc arvv.:r,vi the p'v.r.cer that demands the longest strol^e
tor tlic V i' tVcv,, v^r in the check-valves^ and this leaka^
sV.ou\^, Iv ::*.vcs: cvttvV. ,»: v r.ce.

§ 21 MANAGEMENT OF AUTOMOBILE ENGINES 13

If the oil is not fed to the pistons in sufficient quantity,
the engine will make the fact known by a laboring sound
and a falling off in power, when both the ignition and the
carbureter are in perfect order. If this occurs, a little extra
oil may be put into the crank-case, where it will be thrown
up into the cylinders in sufficient quantity to ease the engine
until the oiler can be readjusted. A new engine should
have a little more oil on both pistons and bearings than one
that has nm several hundred miles, and it is well to feed
oil to the former until a little white smoke shows in the
exhaust. Black smoke indicates too much gasoline in the
mixture.

24. As elsewhere explained, it is best to use the heavi-
est oil that the weather conditions will permit. Often it
will be found that a heavy oil can be used in summer and a
medium or light oil substituted in winter without a change
of lubricator adjustment, owinor to the light oil flowing
more freely. Generally, however, an increase in feed is
necessary when the lighter oil is substituted.

25. It is well to squirt a few drops of kerosene into
each cylinder at the end of a long day's run, say from 75 to
150 miles. This will loosen any carbon deposit that may
have formed about the piston rings. Kerosene is a very
efficient solvent of the tarry products that act as a binder
for this carbon deposit, although, of course, the carbon itself
is not dissolved. Most engines have compression relief
cocks on the cylinder heads that may be used for introduc-
ing the kerosene ; but if these are absent the kerosene may
be injected through the inlet valves.

26. If the splash system of lubrication is used, and the
oil is fed to the crank-case by a hand pump on the dash, this
pump should be operated every 25 miles or thereabouts,
depending somewhat on the amount of low-gear driving
required. Generally there is a shut-off valve between the
pump and the crank-case, which is to be opened by hand
before the pump is operated.

168--16

U MANAGEMENT OF AUTOMOBILE ENGINES 1 21

An improved arrangement that obviates failure of chect-
valves connected with the hand pump to do their duty con-
sists of a three-way hand valve that in one position admits
oil to the pump and in the other permits the oil to pass
from the pump to the crank-case. This valve is operated
by hand for each stroke of the pump. The pump, of course,
is of a fair size, so that two or three strokes are sufficient
Once in, say, 500 miles, all the oil should be drawn oflE from
the crank-case, the case washed out with kerosene, and
fresh oil put in, as it gradually fouls from carbon passing
the piston, and also gathers grit worn from the bearings.

27. Beyond attention to the lubrication, the daily care
required by an automobile engine is simply the brief regular
inspection to see that ever}' thing is working properly. If a
battery is used for ignition purposes, it will need replace-
ment once in a while, and the operator should keep himself
informed of the battery's condition by occasional tests, so
that he will not be unexpectedly stranded. The tremblers
on the spark coils require occasional adjustment, and the
operator should notice the sound of each one, and file the
contact points square or readjust the springs or contact
screws until the sound is correct.

28. Occasionally, the spark plugs will foul and require
cleaning or replacement. How often this will occur is alto-
gether a question of the particular carbureter used, lubrica-
ting arrangements, and type of plug; and the only general
directions that can be given are that the operator should
adjust the lubricator and the carbureter to prodvce as little
free carbon as possible in the cylinder, and then should
learn by trial how often the plugs require inspection.

21), If the car is used in cold weather, special attention
must be ^avcn to the lubricating and cooling systems. One
item in the daily care c)f a motor that cannot well be neg-
lected is the listening for knocks or unusual sounds. These

\ 21 MANAGEMENT OF AUTOMOBILE ENGINES 15

xiay occur from a great variety of causes, which are fully
ireated in Troubles and Remedies, Nearly all the causes
:liat produce knocking" grow rapidly worse if not attended
:o, and therefore no symptom of this sort should be neglected.

STARTING AN1> STOPPING

30. The regular order for starting an automobile engine
Is given in the following paragraphs. This order should be
followed every time the engine is started, for this is the best
\eay to avoid forgetting things; in fact, the beginner will do
^'ell to memorize these instructions.

1. Open the main gasoline valve at the tank. If the
tank is hung low, and the gasoline is lifted to the carbureter
by air pressure, ascertain — by priming the carbureter if
necessary — that the tank has the required pressure, and
pump air into it by hand, if necessary. A hand pump for
this purpose is mounted on the dash, usually at the left end
Sometimes the gasoline passes through a small auxiliary
tank cm the dash, and this tank holds gasoline enough to sup-
ply the carbureter by gravity until pressure from the exhaust
gases can be raised in the main tank.

2. Retard the spark as far as possible. This is of the
first importance, as the attempt to start with the spark
advanced may result in a broken arm. It is an excellent rule
never to turn the starting crank, even when it is thought
that no explosion can occur, without first seeing to it that
the spark lever is retarded.

3. Set the throttle about one- quarter open.

4. Close the switch and insert the safety plug, if one is
used.

6. Turn on the oil feed. It is assumed that any oiling
and filling of oil cups done by hand has already been
attended to.

6. Open the compression relief cocks, if there are any.

7. Prime the carbureter, by depressing the float or oth-
erwise, according to its construction. If the motor has been
stopped for not more than an hour or two, or sometimes

10 MANAGEMENT OF AUTOMOBILE ENGINES §21

longer, this is not necessary. If the tank has pressure feed,
and the carbureter has been primed to test the pressure
(see 1), it does not need to be primed again.

8. Engage the starting crank, and turn it over until
the resistance due to the compression stroke is felt. If the
starting crank is not now on its up stroke, move it back-
wards a quarter or half turn until it is, and reengage the
ratchet at this new point. Never push the crank over the
compression stroke. Even if the switch is open, a hot motor
may start from preignition, and a **back kick" may result
in a broken arm.

9, Pull the starting crank upwards smartly against the
compression. The motor may start. If it does not, turn
the starting crank until the next compression stroke comes,
and pull it upwards smartly as before.

31. If the carbureter has not been primed too much or
too little, the motor should start unless the gasoline is too
cold to vaporize. If it does not start with the second or
third trial, prime the carbureter again and repeat the opera-
tion. If the motor still refuses to start, something may
have been neglected or forgotten. It may be that the gaso-
line is not turned on, that there is no gasoline in the tank,
or that it is stale or heavy, that the switch plug is not in
place, that the battery is not strong enough, or that the
method of priming the carbureter has given too light or
too weak a mixture. The method of priming is something
that will depend on the individual carbureter, and can only
be learned by experience.

33. The procedure for stopping an automobile engine is
to partly close the throttle so that-the motor will run slowly
and then open the switch; if the stop is permanent, take out
the safety plug, shut off the oil feed, and shut off the gaso-
line at the tank. If the car has been run some distance it is
well to squirt a small amount of kerosene through the com-
pression relief cocks to loosen any carbon deposit that may
have gathered around the piston rings.

§ 21 MANAGEMENT OF AUTOMOBILE ENGINES 17

ABJUSTMBNTS AND RBPIiACEMENTS

TIMING THE VAXVE8

33. When a column of gas moves rapidly, as in its pas-
sage through the admission or exhaust valves of an engine, it
T^quires considerable force to bring them to rest suddenly.
"When the force resisting the flow is small, it requires a con-
siderable interval of time to bring the gas to rest. This is
very noticeable in engines having automatic valves, in which
the force tending to close the valves is small. For this rea-
son, the valve timing of a high-speed automobile engine must
be radically different from that appropriate to stationary
engines. As the beginning and end of the piston strokes
represent considerable crank-angles with very small piston
movement, advantage is taken of this fact to hold the valves
open for a considerably longer time than would theoretically
be required in order to give the maximum opportunity for the
movement of the gases.

The exhaust valve should open at a crank-angle between
30° and 40° before the end of the expansion stroke. This
represents from one-twelfth to one-ninth of a revolution, and
approximately from 5 to 10 per cent, of the piston stroke.
It is a common practice, with automobile makers, to mark
the flywheel rim with reference to some convenient fixed
object, generally the vertical (or horizontal, if the motor be
lorizontal) center plane of the motor. These marks may
ndicate the inner and outer dead centers, or they may indicate
vhat the maker has decided is the suitable crank position for
he exhaust valves to begin to open. In the latter case, it is
5:enerally best to adhere as nearly as possible to the point of
:>pening thus indicated.

34. Although in the majority of automobile engines, the
Exhaust valves close at the end, or dead center, of the

18 MANAGEMENT OF AUTOMOBILE ENGINES g S\

I exhaust stroke, it has been demonstrated conclusively that
I there is a marked advantage in holding the valves open until

the crank is 5° or even 10° past the center. The latter angle
L represents a piston movement of only about 1 pt-r cent of
the stroke, and no fresh mixture will enter during this
period; whereas the prolonged opening of the exhaust
valve permits the gases in the exhaust pipe to create a slight
suction in the combustion chamber by virtue of their own
inertia, thus tending to induce the flow of a larger charge of
fresh mixture. If the exhaust valves are held open unii!
the crank is about 10° past the dead center, it is unnecessary
to open them quite so early on the expansion stroke as would
otherwise be considered necessary. A good average rule is
to open the exhaust valves 35°, or practically one-tenth of
the circumference of the flywheel before the end, or dead
center, of the expansion stroke, thus making the total opening
of the exhaust valve about 223" of the revolution of the fly-
wheel. If the engine is to run at speeds upwards of l.fiOO
revolutions per minute, an earlier opening and later closing
may be of advantage.

35, If the inlet valve is located over or beside the ex-
haust valve, it should open with the crank about 5° past the
center. If it is on the opposite side of the engine from the
exliaust valve, it may open on the dead center, thus permit-
ting a direct suction across the combustion chamber that will
greatly augment the power of the engine. The inlet vslve
should close about 20" to 30" past the dead center at the end
of the suction stroke, or approximately 2^ to 5 per cent, of
the piston stroke. The reason for holding open the inlet
valve is that at high speeds the inertia of the incoming col-
umn of the mixture will carry it into the cylinder after tbe
return stroke has begun.

hreafl^H
; Iwo-l^^

36. The valve timing is usually adjusted by thrt
adjusting ends on the push rods; also, by shifting the Iwo-tc
one gear one tooth or more in relation to the pinion. If the
total duration of opening of the exhaust valve is less than

§ 21 MANAGEMENT OF AUTOMOBILE ENGINES 19*

230°, after making due allowance for necessary clearance
between the push rod and the valve stem, it is advisable to
substitute new cams or else to build out the old ones. This
can sometimes be done by dovetailing in a
segment, as shown in Fig. 2. Generally, it
will be necessary to anneal the cams before
this can be done. The inserted piece is bet-
ter located if possible in the closing face of
the cam, as it is subjected to less wear on
that face than on the other. It should be
made of tool steel, and after being tightly ^®'*

driven in and fastened with a rivet or screw, should be hard-
ened with the cam.

If the inlet valves are operated by the same shaft as the
exhaust valves, it may be impracticable to alter the valve
timing by shifting the two- to-one gears. In this case, it will
be necessary to alter the cams.

RETIMING THE IGNTTION

37. The timing of the ignition may be tested for uniform-
ity by marking the flywheel in the same manner as for timing

the valves. In case it is found
that the cylinders are unequal-
ly timed, the timer should be
adjusted according to its con-
struction. If the timer has a
cam that presses springs in
contact with contact screws,
the timing may be modified
by adjusting the contact screws
so that a little more or less
movement of the cam is re-
P^o-* quired to produce contact. If

the timer has a fiber barrel a with an inlaid copper or brass
segment ^, as shown in Fig. 3, the only way the timing can
become incorrect is through wear of the hardened-steel
blocks r, r, at the ends of the contact brushes, or through

20 MANAGEMENT OF AUTOMOBILE ENGINES § 2

loosening and slipping of these brushes, which are general!;
slightly adjustable on their insulated bases d^ d.

When these blocks have worn down considerably, it is wel
to grind away a portion of their contact surface at the beai
ing edge, as seen in the detail at e^ otherwise, considerable^
pressure will be required to make good contact at the leading ^^%
edge / and this will wear away the barrel and metal sej
ment unnecessarily fast When the timing is tested, the spar-
should always be retarded to its fullest extent, and in th:^
position the spark should occur in each cylinder exactly o«
or a definite number of degrees after, the crank has passe^^i^ed
the dead center

RKPULCING EXHAUST- VAI.VK KSTS

38. On account of the inertia of an exhaust valve of an
engine running at high speed, the springs that close m^he
valve must be very stiff, and it is sometimes a problem to
get them back in place after they have once been taken -^out
— as, for example, to regrind the valve.

To replace the spring, it must first be compressed i:i3 a
\4se and bound securely on opposite sides by two pieces
of annealed wire. When this is done, the spring ma)'^ be
put back in place, the valve dropped in, and the washer
and key properly inserted. Then the wires binding the
spring may be cut with a pair of pliers and the spring
allowed to expand. The spring should bear squarely on \ht
washer.

In a few engines, no washer or key is used, but the lower
end of the spring itself is bent inwards and flattened to go
in a slot in the valve stem. In this case, the spring may be
taken out from the valve stem by first blocking up the
spring in the same manner as is. done when the washer is •
used, and the spring may be replaced by compressing an^
binding it as just described, holding the valve in the proper
angular position with a screwdriver, while the end of the
spring is first pulled and then pushed into position with a
strong pair of pliers.

§ 31 MANAGEMENT OF AUTOMOBILE ENGINES 21

MAKING VALVE-STEM KEYS

39. Valve-stem keys should be made of annealed tool
^teel, and should not be made too close a fit in the valve-stem
^lot, because they are likely to bend slightly in use. Ordi-
narily it is cheaper to buy these keys of the maker of the
c:ar than to make them specially. One or two spare keys
should always be carried.

TAKING OFF AND REPLACING CYLINDERS

40. In case it becomes necessary to replace the piston
Tings or to scrape out the combustion chamber, it is neces-
sary to take off the cylinder. If the engine has more than
one cylinder, the cylinders are probably marked to identify
them severally for replacement. These marks should
be looked for, and, if not found, marks should be put
on. When the cylinders are off, care sliould be used to
avoid handling the pistons in such a manner as might break
their lower edges, which are very thin. When the cylinder
is off, it is a good plan to inspect carefully the surface of the
cylinder wall and the piston and ring surfaces, to see if they
have been scored by lack of oil or water. The cylinders and
pistons of a well-kept engine will show a bright, almost
mirror-like surface, free from scratches.

4:1. If the piston rings are clogged w^th carbon, it is, on
the whole, better to clean them as well as possible with ker-
osene, while in position, rather than to take them off, as the
bending of the rings is liable to strain them out of true,
a.nd cause leakage when they are replaced. In case it seems
advisable to take off the rings, each ring should be marked
with a small, sharp prick-punch, and the corresponding
^oove marked, so that each ring will be restored to its own
^oove. To take off the rings properly and without risk of
straining requires considerable care. A good method is to
use three or four narrow strips of tin or thin brass, which
first slipped under the ends of the ring nearest the head.

22 MANAGEMENT OF AUTOMOBILE ENGINES § 21

and gradually worked around until the ring* is out of its
groove. The same strips are used to bridge the grooves
when the other rings are taken out.

When a cylinder is to be replaced, the piston rings must
be compressed and tied, else it will be a difficult matter to
get the piston into the cylinder. As each ring is started in
the cylinder, its binding is removed.

SCRAPING C^VRBON FROM COMBUSTIOIT CHAMBER

43. A refractory deposit of carbon in the combustion

chamber may be loosened with kerosene and scraped out
with anything convenient, such as a cold chisel or an old file
with the end ground sharp. If it is inconvenient to take off
the cylinder, it is frequently possible to remove or reach the
carbon through the spark plug or valve holes, the scrapers
for this purpose being generally iron rods with the ends
flattened and bent to suit the conditions to be met An
exceedingly useful outfit is a battery lamp of 2 or 3 candle-
power, with a length of No. 16 lamp cord, by which it may
be connected to the battery, and an ordinary plain (not mag-
nifying) dentist's mirror. The lamp is screwed into a min-
iature socket, and a length of iron wire is wound into a coil
around the cord adjacent to the socket, the coil being
extended to include the socket and the lamp, thereby forming
a protective cage for the latter. It must, however, not
touch the lamp.

43. By the use of such a lamp, almost every inch of the
combustion chamber of an ordinary engine can be explored
and scraped, and the carbon can be pulled out through the
spark-plug hole; or, if more convenient, the exhaust valve
may be opened and the accumulation allowed to fall into
the exhaust port, from which it will be carried to the muf-
fler. It is better, however, to take the exhaust valve right
out than simply to open it by the cam, as only in this way
can one be sure that none of the carbon lodges between the
valve and its seat, thus necessitating regrinding. When the

§21 MANAGEMENT OF AUTOMOBILE ENGINES 23

carbon h scraped out in this manner, it is better not to use
kerosene unless it is necessary, as it increases the likelihood

of loose carbon fragments sticking to the combustion cham-
r walls and causing further trouble from prei^tioo.

24 MANAGEMENT OF AUTOMOBILE ENGINES §21

ARRANGEMENT OF ENGINE ANB AUXIXJABIE8

44. Assembly drawings, showing the Icx^ation of the
engine and some of the auxiliaries, are presented in Figs. 4 and
5, the same letters of reference being used to indicate simi-
lar parts of both illustrations, which serve to show one of
many possible schemes of arrangement. The air-cooled cyl-
inders a are bolted to a closed crank-case b^ supported, as
shown, by two angle-iron cross-members of the frame on
which the body of the car rests. Air is supplied to the car-
bureter c through the intake pipe d ; while from the carbu-
reter, the charge passes through the pipe e to the supply-
pipe for the four cylinders. Protection against accidental
injury to the secondary cables is afforded by a fiber tube/
from openings in which the cables are led to the spark
plugs g.

The governor on the cam-shaft is enclosed by the casing A,
in front of which the spark timer i is located. The rock-
shaft /, Fig. 4, controlling the spark time, is operated by the
lever j\^ Fig. 5, connection between the spark lever under
the steering wheel and the rock-shaft/ being made by the
rods k and /. • Adjustment of the proportions of the explos-
ive mixture is effected by the rod w, operated by hand.
The steering column is shown at n. The exhaust valve o
and the inlet valve /, as well as auxiliary exhaust valves not
shown, are mechanically operated by push rods actuated by
cams mounted on a single cam-shaft. The auxiliary and
main exhaust pipes are shown at q and ^„ respectively.

A pulley r for operating a mechanical oiling device is
mounted on the end of the cam-shaft, as shown. A rod s,
Fi^. 4, operated by the throttle lever /, Fig. 6, controls the
position of the throttle. The circulation of air over the
cylinders is assisted by the use of fan «, Fig. 5. The coil
box V and the mechanical oiler li) are mounted on the dash,
as shown in Fig. 5, the batter}' boxes x. x, being carried on
the steps. The transmission gearing is enclosed in the cas-
inir i\ outside of which is located a brake ::.

26 MANAGEMENT OF AUTOMOBILE ENGINES § 21

MISCELLANEOUS SUGGESTIONS

COLD- WEATHER HINTS

45. In cold weather, the circulating water, the oil, and
the carbureter, require special attention. If the car is to be
run regularly during the winter, it is advisable to use a non-
freezing mixture in the water-jacket. If the car is not to
be used regularly, it may not be necessary to employ such a
mixture, but in that case great care is necessary to prevent
the water from freezing unexpectedly. If the car is kept in
a barn, the water should be drawn off completely after the
car has been used, and the drainage cock should be so located
and the piping so arranged that there are no water pockets
in which the water may freeze and obstruct the circulation.
If the water freezes in the pump, the latter is likely to be
broken when the car is started the next morning. If water
freezes in the water-jackets, it will burst the jackets unless
they are made of copper. When the car is left standing
for an hour or so, cloths or lap robes may be thrown over
the radiator to check the cooling; this is cheaper and safer
than leaving the motor running.

46. The two substances most used to prevent freezing
are glycerine and calcium chloride. A 30-per-cent. solution
of glycerine in water freezes at 21° F. ; and a solution of one
part of glycerine to two parts of water is safe from freezing
at 10° or 15° F. ; 40-per-cent. solution freezes at zero. A
small amount of slaked lime should be added to neutralize
any acidity in the solution. Glycerine has the objection
that it destroys rubber, and the solution fouls rather quickly.

A cheaper mixture, and one preferable where the tempera-
tures encountered are likely to be below 15° or 20° P., is a
solution of calcium chloride. This must be carefully dis-
tinguished from cJdoridc of lime (bleaching powder), which
is injurious to metal surfaces. Calcium chloride costs about
8 cents a pound in bulk, and does not materially affect

§^I MANAGEMENT OF AUTOMOBILE ENGINES 27

^^tals except zinc. A saturated solution is first made by
adding about 15 pounds of the chloride to 1 gallon of water,
^^king a total of about 2 gallons. Some undissolved
^^stals should remain at the bottom as evidence that the
^lution is saturated. To this solution is added from 2 to 3
Salons of water, the former making what is called a 50-per •
^nt solution. A little lime is added to neutralize acidity.
A. 50-per-cent solution freezes at — 15® F.

47. Whether glycerine or calcium chloride is used, loss
^y evaporation should be made up by adding pure water,
^nd loss through leakage by adding fresh solution. In using
tihe chloride, it is important to prevent the solution from
Approaching the point of saturation, as the chloride will then
c^rystallize out and clog the radiator, besides boiling, and fail-
ing to cool the motor. A 50-per-cent. solution has a specific
^^vity of 1.21, and should be tested occasionally by means
of a storage-battery hydrometer. Equally important is it to
prevent the water from approaching the boiling point, what-
ever the density, as boiling liberates free hydrochloric acid,
which at once attacks the metal of the radiator and cylinders.

A solution of two parts of glycerine, one part of water,
and one part of wood alcohol has been recommended, which
is said to withstand about zero temperature.

48. Certain mineral oils used for the lubrication of refrig-
erating machinery are recommended for cooling, because
they remain liquid at very low temperatures. They are not
particularly good heat conductors, however, and will not
keep the motor as cool as the water solution. If the oil is
used, it must be cleaned from the radiator by the use of kero-
sene and oil soap, before water can again be used effectively.

49. As regards lubrication, the principal danger is that
the oil will thicken from the cold so that it will refuse to
feed. This is avoided by using cold test oily which remains
liquid at lower temperatures than ordinary oil, or by adding
to the ordinary oil some kerosene or gasoline, and increasing
the teed. It the oil tank is located close to the engine, it

28 MANAGEMENT OF AUTOMOBILE ENGINES §S

will remain warm even in quite cold weather; but, unle
the car has been kept in a warm place over night, the bea-
ings are liable to run dry before the car has warmed up.

50. The temperature has a very marked effect on tK
rapidity with which gasoline vaporizes, and in cold weatlL*
it is necessary to supply heat to the carbureter. The ca^
bureter should preferably be jacketed, and it may T
warmed either from the circulating water or by takings
small quantity of the hot gases from the exhaust pipe,
water is used, it should be taken from a point just beyond tl
discharge of the pump, and should be delivered to the retix:
pipe from the engine jacket to the radiator. Whetfci
exhaust gases or water is used, the flow should be regulate
by a cock, otherwise too much heat will be received in wJLir
weather.

When the carbureter is cold, the engine may be starte
by pouring warm water over it, care being taken not to le
the water get into the gasoline through any aperture in th
top; or cloths may be wrung out in hot water and wrappe*
around the carbureter. Fire of any sort should never b
used.

GASOLTNE-HANDLIXG PRECAUTIONS

61. The user of gasoline should never forget that it is j
the liquid gasoline, nor yet the vapor of gasoline, tha'
explosive, but only the mixture of gasoline vapor and ai
the right proportions. If the liquid gasoline were nc
volatile, it would be as safe to handle as kerosene, in v
one may plunge a lighted match without igniting it, ther
instead being extinguished by the cold oil. But since ga
evaporates rapidly when exposed to the air, it is not e
to avoid bringing a lighted match, a flame, or an e
spark within the vicinity of the liquid — as, for examph
gasoline has been spilled on the floor or on the groui
one must also avoid any possible source of ignition ai
in the neigh borhoc^ until the air has changed suffic
dilute the vapor below the point of inflammability.

•^1 MANAGEMENT OF AUTOMOBILE ENGINES 29

*1 the accidents due to the handling of gasoline arise simply
ro?ii carelessness in neglecting these precautiona

Air saturated with the vapor of gasoline will bum
^allowed to come in contact with fresh air, but it will not
xplode, as the proportion of gasoline vapor in it is too great-
t follows that a can or tank containing gasoline is safe from
xplosion if the vapor of the liquid is saturated, and this is
he condition that will naturally obtain if the liquid has been
Irawn off so gradually that its place has been filled with air
in.d saturated vapor. If, on the other hand, the can or tank
las been emptied quickly, air will enter it to take the place of
-he liquid poured out, and the proportion of vapor will not be
sufficient to prevent it from being explosive. This is the
most dangerous condition possible, and calls for the strictest
precautions to prevent the ignition of the mixture therein.

1«»— 17

;»

' ' I

MANAGEMENT OF MARINE

GAS ENGINES

MABINE-ENGEN^E INSTALLATION

XOCATION OF ENGINE AND AUXII.IARIE8

X. An installation diagram such as is shown in Fig. 1
^^*Ves the double purpose of guide and working plan, indica-
^'^^gf the position of the engine and showing the location and
^^^^ngement of the accessory apparatus forming part of the
P^'W'er equipment

-A^inong those parts to which subsequent reference will be

^*^^^e in the text are the shaft log a^ stern post b^ dead

^^^^>d Cy compression coupling //, sea cock r, muffler /, and

^^^^c^line-supply tank g. Other parts to which no specific

'^^^rence will subsequently be made are as follows: engine

^^lisust pipe h leading from the engine to the muffler /"and

^^^^xiected up by means of two unions /, / and an elbow, a

f^^'tciocky being located at the lowest point in the pipe; bat-

^^^"3^ * and spark coil /, Fig. 1 {b) ; outboard gasoline-supply

^I^^ w, Fig. 1 (a), from supply tank g to carbureter 7i,

.^^T- 1 (^); reverse rod o for forward, or bow, control, con*

^^^^ng- of a galvanized -iron pipe with ends shaped for

^^■^Hection to the reverse-sfear mechanism and to the lower

I ^^ of the reverse lever, which is held in the bracket/, the

, ^^^r q being the regular reverse lever, which for use in the

^^ of the boat can be removed from its usual position at q'

^Ixe gear-case r; air pipe s leading to the whistle tank /,

hf hUemoHonai Textbook Company. Entered at Stationers? Hall^ London,

|33

2 MANAGEMENT OF g %i

to which the signal whistle is attached; brass strainer u
the outlet pipe in the gasoline tank; hand wheel v f
operating the valve in the gasoline-supply pipe; and br;
tank plate w, provided with two small vent holes.

To install a marine gasoline engine so as to insure maxi<
mum safety and freedom from excessive vibration necessi*
tates a thorough understanding of all the requirements
be met, including the construction and location of the fue
tanks, engine, carbureter, piping, etc. , and also a thoroug!
knowledge of the operation of the engine. Before an
attempt is made to install the engine, there should be pro- ^
vided a working blueprint or drawing, indicating the dis-
tance from the center line of the crank-shaft of the engine
to the under side of the bed or lugs, giving all the dimen-
sions and showing plainly the outline of the base below the
bearing side of the lugs. A drawing of the longitudinal
and athwartship, or crosswise, pieces, with the dimensions
plainly marked, should accompany the drawing of the engine
base.

2. When the boat is new, the shaft hole is usually bored
before the shaft log a and the stem post ^, Fig. 1 (tf), are
put in place; if, however, it is necessary to bore the shaft-]
hole, the work should be intrusted to some one of experi-
ence, as it sometimes becomes necessary to make important
changes in order not to weaken the boat or render it unsafe.

If the shaft hole has been bored, a line should be run
from the center of the outboard, or outer, end, in the
direction to be occupied by the center of the propeller shaft,
to a point considerably beyond where the front of the
engine will come. From this line, measurements should
then be made to determine whether or not there is suflScient
room for the engine, reversing gear, flywheel, eta To
obviate any chance of error, the measurements on the dia-
gram or drawing should be verified by measuring the
engine, so that, when once in place, the engine need not be .
removed. There is usually a keelson a, Fig. 2, a timber ,
nmning the whole length of the boat and fastened to the

1 1 1.

. .OKK
PUBLIC LIBRARY

ASTOF». l.f NOX ANO
TILD? N FOUNOATioNg,

§ 22 MARINE GAS ENGINES 3

keel b over the ribs c^ Figs. 2 and 3. For the purpose of
strengthening and stiflfening the frame, the ribs are also
frequently fastened to similar pieces, called bilge keelsons^

running lengthwise of the boat. If hauled out of the water,
the boat should now be leveled up. A plumb-bob dropped
from the above-mentioned line at its forward end should
mark the center line of the ke6l or of the dead wood c,

3. Transverse pieces of oak rf. Fig. 2, of sufficient thick-
ness should be let down to the planking e^ fitting closely
over the keelson, and securely bolted into or through the
keel and fastened to the planking and to the timbers, as
shown in Fig. 2, which serves to illustrate one method of
placing engine-foundation timbers. The timbers //, when
fitted to the bottom of the boat and securely fastened to the
planking, sometimes serve to form bulkheads, or partitions,
extending all the way across the boat. Figs. 2 and 3
show the transverse pieces let down between two tim-
bers^ y running fore and aft, or lengthwise, and serving as
the foundation through which the stresses set up by the
engine are distributed throughout the whole bottom surface
of the boat, thus lessening the vibration.

At the lowest points on both sides of the keelson, limber s,
or small spaces between the planking and ribs, should be
cut to allow water to pass through ; or some means should
be provided to pump out from each compartment separately
any water that may collect there. When the latter and the
safer method is employed the bulkheads should be made

MANAGEMENT OF

water-tight, the lower edges being bedded in red-lead or
white-lead putty.

If there are two or more compartments under the engine,
they should be connected so that drippings of oil from the
engine and gasoline from possible leaks at the carbureter
may collect there, to be pumped out by hand or with a
pump operated by the engine. This method of disposing of

I ft I I I

5^.

drippings is better than having no drip pan under the
engine, and in a cabin boat should always be used eveft with
a drip pan under the engine; otherwise, an accumulation of
gas in the cabin space is liable to be ignited andlo explode
with grave resnlts.

With a twin-screw installation using two separate engines,
the longitudinal timbers on which the engines rest may be

§ 22 MARINE GAS ENGINES 5

let down a little way into the bulkheads and cut away
slightly, so that the bulkheads themselves may securely
support the longitudinals, which may have to be cut away or
entirely cut off to allow room for the flywheel, but the
longer they are the better. Almost any hard wood will do,
but nothing is better than good sound oak.

4t» The size of lumber used in engine beds depends
entirely on the engine. The ordinary single-cylinder
engine requires a heavier bed than almost any other, except
a two-cylinder, four-cycle engine with cranks 180° apart.
Sometimes, single-cylinder engines are constructed with
what are known as couuterwelgrlits attached to the crank-
shaft on the side opposite to the crankpin or to the flywheel
in a similar position, the object being to balance the weight
of the piston, crank, and connecting-rod. When balance
weights are employed, it is not necessary that the bed con-
struction should be quite so heavy. With four-cycle
engines, even with counterweights, beds should be more
substantial than for two-cycle engines, as the explosions do
not occur so often, and, being more powerful, are more
likely to cause excessive vibration.

Double-cylinder four-cycle engines with cranks opposite,
or 180° apart, require an engine bed of the heaviest con-
struction, because there are two impulses during one
complete revolution of the crank-shaft, the explosion in the
second cylinder following closely upon that in the first,
accelerating the crank-shaft speed ; a complete idle revolu-
tion follows; the latter half of the revolution, being against
the compression, causes a particularly unpleasant vibration
that, unless absorbed by the engine bed or the boat itself,
may be unsafe because of the light construction of the boat
or the presence of some defect. Two-cycle engines of twp
or more cylinders and four-cycle engines of thr^e or more
cylinders are better balanced and do not require such heavy
beds.

5. In some cases, it has been found necessary to put in
braces from the top of the engine to the side of the boat, the

6 MANAGEMENT OP § 22

engine bed and lower part of the hull being too light. It is
customary to make the hull where the engine is to be
placed of much heavier construction by putting in a double
framing of extra or heavier ribs. Weak engine beds may
sometimes be strengthened materially by filling in about
the timbers with Portland cement and sharp sand.

It is rarely found necessary and is hardly advisable to fasten
engine beds through the ribs and planking, as is often done
in marine steam-engine, practice, for such fastening tends to
weaken the hull construction instead of strengthening it.

A drip pan of good depth under the engine is necessary
for catching all dripping oil, and, if connected to another
pan under the carbureter, gasoline that may leak there will
be prevented from getting into the hull of the boat, running
into the drip pan instead, from which place it may readily
be pumped out This drip pan should be fitted under the
base of the engine and to the hull before the engine is in
place. The edges should be flanged over the longitudinal
pieces of the engine bed, which should be cut away so that
the engine base will not bear on the edges of the drip pan.
Copper makes the best material for a drip pan, but galvan-
ized iron may be used in fresh water only, the outside of
the tank being well protected with asphaltum varnish,

6. Before placing the engine on the bed, be sure that
the two longitudinal timbers are not in wind, that is, with
the end of one higher than the same end of the other. This
would make the engine rest like a four-legged chair with
one short leg. To determine whether or not there is
wind to the bed, place a level squarely across both forward
and after ends, or build up the after ends alike until they
are both level, and see whether or not both longitudinal
pieces are true. A little variation from a true level wnll
make quite a difference in the character of the stresses set
up when the engine is in place and operating. It may be
necessary to cut away a part of one or more of the bulk-
heads to make room for the base or reversing gear.

If, ha\nng the en.crine on the bed, the engine base is

§ 22 MARINE GAS ENGINES 7

continued to support the reverse gear r, Fig. 1, put in the
propeller shaft, put on the stuffingbox and separate stem
bearing if one is used, and, if the propeller shaft is to be
coupled by means of a sleeve coupling, see that the ends of
the shaft project into each end half way, with the key
removed, and that the propeller shaft turns freely. If a
compression coupling d^ Fig. 1, is used, see that both shafts
are in line. If the two shafts are flanged, see that they
come fairly together, moving the engine slightly, if neces-
sary, in order to get the shafts absolutely in line, and block-
ing up the forward or after end of the engine, if necessary,
being particular that the propeller shaft does not touch the
side of the lead sleeve in the shaft log a, Fig. 1. If a brass
sleeve is used, it should not be fastened until the engine is
lined up, as stern bearings and stuffingboxes are usually
screwed into the brass sleeve. Lead sleeves are usually
considerably larger than the shaft ; their ends are flanged
over and copper- nailed, after being bedded in putty consist-
ing of white lead stiffened to the proper consistency with
red lead. Where no sleeves at all or lead sleeves are used,
stem bearings and stuffingboxes should be fastened flush
with the ends of the shaft log, by means of bronze screws

!^^1»\\UUUU1W»UUI

Fig. 4

when the stuffingboxes and stem bearings are of bronze,
and by means of iron or steel screws when iron stem bear-
ings are to be used. Iron or steel stem bearings should
never be used around salt water, except with very large
shafts, lignum-vitae bushed stem bearings and bronze
bushings always being used on steel shafts. While bronze
lag or coach screws as sent out from the factories are usually
employed, a much better custom is to use bronze studs with
a wood-screw thread on one end and a bolt thread on the
other, as in Fig. 4. These studs can be screwed into place
by screwing on a nut half its thickness and screwing

MANAGEMENT OF JM

another stud down hard against the firat, as in Fig. 5. A
stud driver Fig. 6 may also be used. This consists of a
square or hexagooai piece of metal a, threaded as shown to
receive the machine- screw end of the stud 6, which is locked
in place by the capscrew c while the wood-screw end is
being screwed into place. One special precaution to be

observed in fastening all stem bearings and stuflBngboxes is
to see that they rest squarely against the wood and that a
thin layer of red-lead putty is placed between the metal and
the wood, the metal being drawn into place so that it does
not bind the shaft

7. Small engines are usually fastened to their beds by
iron screws, but a more satisfactory fastening will be found
in steel or iron studs, similar to the bronze ones used- fw
fastening the stem bearing and stiifEngbox. In case of
necessity, it will be found much easier to remove a few
nuts than to remove the coach screws, especially after they
have been in place a year or so. Wlien it becomes neces-
sary to line up an engine with a separate reversing gear, the
shaft of the latter should be sufficiently long to extend from
the after bearings to the crank-shaft. After lining up the >
crank and propeller shafts, a temporary bearing should be
erected abaft the reversing gear, which is usually supported
with a thrust, the gear shaft then being lined up with the
crank and propeller shafts and securely fastened.

If it is found necessary to raise either end or side of the
engine to line it with the shaft, thin pieces of iron or tin
will be found very convenient, or thin pieces of hard wood
may be used.

8. In case the flywheel is shipped separately, or lias to
be removed to get the engfine into place, it should, if bond :

§ 22 MARINE GAS ENGINES 9

Straight and the key driven in, be replaced carefully in
exactly the right position, noting that the key rubs on all
four sides by taking it out two or three times after starting
to see that it fits. If the flywheel is fitted on a taper, as is
sometimes the case, care should be exercised that the key
does not prevent the wheel from going into its proper posi-
tion on the shaft because of its being too thick or being
placed wrong side up. Flywheel keys should always fit on
both sides as well as top and bottom, and should be oiled
before being driven into place. Occasionally, a flywheel and
a crank-shaft are found in which the keyways are cut a V
shape and extreme care should be used in driving in the key,
for there is great liability of splitting the hub of the fly-
wheel.

The fastening of flywheels securely to the crank-shaft
is such an important matter that some manufacturers make
the crank-shafts with a flange on the flywheel end, the flange
being bolted to a web in the flywheel.

9. In some cases it will be found necessary to take the
engine apart more or less to get it through a companionway
or skylight. If the operator or other person making the
installation has had much experience with machinery, he
will observe much caution in taking it apart, marking each
piece, usually with a center punch, so that each gear will
mesh with the same teeth when putting together again, and
each part will go back to its proper place. For thus marking
the parts, a center punch and a light hammer will be found
indispensable.

10. The alinement of the engine and propeller shafts is
an important proceeding, more particularly if no universal
coupling is used. In extremely light boats, as in yacht
tenders, and when using engines designed to be installed
level or more nearly level than the propeller shafts, universal
couplings are necessary. They are of numerous forms and of
varying utility; the greater the angle between the two shafts
thus connected, the more unsatisfactory is their use. While
the engine and propeller shafts are being lined up, the boat

MANAGEMENT OP

§^

should be blocked up evenly along her keeL No matter how
carefully the work of lining the shafts may be done, it will
be necessary to reline them after the boat has been put in
the water and has assumed her normal shape. When the
engine shaft is in line with the propeller shaft and the stem
bearing and stuffingbox are securely fastened, the engine
should be fastened to the bed, after which the water and
exhaust piping may receive attention.

PIPING AND GASOIilNE TANKS

PIPING

11. In piping up for the circulating water, care should
be exercised that leaks do not develop at the sea cock (,
Fig. 1 (a)^ where the water from the outside enters the boat
The usual method of making the sea-cock connection is to
use a long brass nipple, \\\\h a locknut outside and inside, and
with washers underneath. In some cases, the water connec-
tion is arranged as shown in Fig. 7; it is put through fro"^
the outside of the plank, with a brass washer a under tt*-®

TT77STT

Fig. r

sluMiKlor »*, tV.o whole being held in place by a brass locknu
\\'.:> Wvw.en \v.i>heis ur.deriiea::: it. The water piping
\\w\ Svvcwed iv^ r::c inr.er er.vl. A ir.uch safer method c

>s:^ o! r*.::":'.j^ tv^ :;'.o i:isiJ.o v :" I'/.o rl.irkir.gablockof wood V

vv : »reo :'"!*o> .;<

v. N

.\< :Vo r'.r.k rv:. The buxrk is bedd

S S2 MARINE GAS ENGINBS 11

in putty, and is then carefully and solidly fastened to the
planking. A hole just large enough to admit of passing
through it a piece of lead pipe of good thickness, and having
a clear way fully as large as the inside of the pipe to be used
for the water suction, is then bored through the block and
planking. The hole should be chamfered outside and inside.
One end of the lead pipe should be flanged out and ham-
mered into the chamfered edge at the inner end of the hole
in the pipe, being cut off about ^ inch beyond the outer end
of the hole. Then holding in place the inner end, the outer
end should be flanged over and nailed with copper nails
spaced rather closely, being sure to have white or red lead
under the flanges. A brass railing flange can now be
screwed to the end of a short annealed-brass nipple, which

had better be soldered in to obviate danger of unscrewing in
case it should ever be necessary to remove the piping, stop-
cock, or valve attached to this nipple. The flange should
then be bolted against the inside end of the lead pipe, as
shown in Fig. 8, using button-head brass bolts, which
pass through the outside planking. If long brass wood
screws are used, they should be cut off outside the planking.
The piping should be led to the pump suction, using two or
three regular or ib" elbows, and a sufficient length of piping

12 MANAGEMENT OF § 22

and number of fittings to take up vibration without causing
leaks or other injury to the planking. Rubber hose is some-
times used; but, unless the piping is led to a point higher
than the water-line, and kept above it, a leak might fill the
boat with water.

Whether a reciprocating or rotary pump is used, there
should always be a check- valve close to the suction end of
the pump to keep water in the pump and engine cylinders
when the engine is not running; otherwise it would be
necessary to prime the pump when starting, and the cylin-
ders would remain hot for a long time after stopping. For
use in cold weather, it is necessary that means be provided
for draining the water piping to prevent freezing of the
water and consequent injury to the piping and water-jacket
The piping between the pump and the engine is usually pro-
vided and put in place by the manufacturer, but if no means
of draining it is provided drip cocks shotdd be put in.

Outside the hull, where the circulating water is taken in
through the sea cock, there should be a flat copper or brass
strainer to prevent grass or other foreign matter from being
drawn into the pump or from stopping the action of the
check-valves. The holes in -the strainer should be fairly
close together, and about ^ inch in diameter. The metal
should be fairly heavy, and the strainer should be securely
fastened to the hull by means of small brass screws.

13. The discharge water piping in a multicylinder engine
should always lead from the highest part of the engine, that
is, from the forward instead of the after cylinder. In order
to avoid danger of bursting the cylinder, no valve should ever
be placed in the discharge piping. The best method is to
branch the discharge, running one pipe into the engine exhaust
pipe and the other outboard, the outboard branch being pro-
vided with a square-headed cock. As there is always a cer-
tain amount of pressure in the engine exhaust pipe, the dis-
charge water would naturally flow more freely through the out-
board branch and cock; but a part of the discharge watermay
readily be diverted to the engine exhaust from the outboard

§ 22 MARINE GAS ENGINES 13

discharge pipe by partly closing the cock. If conditions were
such that too much water was diverted to the engine exhaust,
and if it were found impossible to reduce the amount of
water by means of the cock in the outboard discharge branch,
the cock should be placed in the branch to the engine
exhaust, being removed from the outboard discharge, lest by
any chance both discharges shoijld be closed, in which case
the pressure created by the water pump might burst the
water-jacket.

13. When it is necessary to install an engine with the
top of the cylinder lower than the water outside the boat,
extreme care should be exercised that the discharge water
does not get back into the cylinder through the engine
exhaust by way of the exhaust valves or ports. One of the
best methods is to water-jacket the engine exhaust pipe, the
water-jacketing pipe being led outboard or run to the muf-
fler or to the highest part of the exhaust piping where the
water cannot run back to the engine. Under no conditions
should engines constructed so that a part or all of the jacket
water is discharged around the engine exhaust be installed
with the top of the cylinder below the water-line, unless
some means is devised to prevent the water discharged into
the jacket about the exhaust from entering the cylinder
through the exhaust pipe. The water from the cylinder
head is sometimes discharged into a space about the muffler,
the water entering the exhaust piping when it reaches a cer-
tain height

Attempts have been made to overcome the difficulty due
to the passage of water from the exhaust pipe to the engine
cylinder, by placing a valve in the branch to the exhaust
pipe, closing the valve when the engine stops and opening it
when the engine starts. As a result of forgetting to open
this valve, the exhaust pipe and muffler may set the boat
afire ; and were the operator to forget to close it, the cylinders
may fill with water. If the exhaust pipe can be run high
enough at the engine to drain away from it, the jacket water
may safely be discharged into it at this high point; but it is

14 MANAGEMENT OF §22

best not to run water into the exhaust pipe, an inside water-
jacketed exhaust or outside cooling method being preferable.

14. The best location for the sea cock, or water intake,
is a few inches below the water-line, for at that point the
cock is less liable to get clogged with sand or grass. With
a good strainer over it, it ca^ easily be reached and cleaned.
If, however, the boat is what is known as an auxiliary^ that
is, a boat intended to be propelled by both sail and power, it
is a good plan to locate the sea cock lower down, in order to
be sure that it will always be submerged.

In reducing the amount of water thrown by the pump,
it is always best to throttle it at the suction, never at the
discharge.

Another thing to remember is that the water piping should
be run so as to avoid any possibility of flooding the boat
through siphonic action.

1 5. For use in salt water, the piping should be of annealed
brass, which is easier to install and safer because of freedom
from corrosion. Sharp turns in piping are to be avoided
where possible, and the use of 45° elbows instead of the
regulation 90** elbows is always advisable.

In sight, and at places handy to get at, malleable-iron
fittings should be used ; but out of sight, and in close quar-
ters, cast-iron fittings will be found better, because they can
easily be broken, especially if it is ever necessary to take
down the exhaust piping. It is always advisable to use
plenty of graphite and cylinder oil in making up exhaust-
pipe joints. Flanged unions will be found preferable to
ordinary malleable-iron unions, for it will usually be found
easier to cut off the flange bolts than to take down a screwed
union after it has been used a season. Graphite and cylinder
oil or graphite pipe grease will be found better than red or
white lead in making up joints in the water piping.

16. The engine exhaust maybe piped outboard in many
ways, the simplest being to pipe it directly through a muflfier

MARINE GAS ENGINES

arranged vertically. While simple, this plan is not often
adopted. A dummy stack makes an excellent place for an
exhaust, but it would not be safe or expedient to run jacket
water into it, because the water would run back into the
engine. In many open launches, it is found quite conven-
ient to exhaust through one or both sides of the boat. In
most cases, especially in auxiliaries, the exhaust should issue
at or above the water-line. Some boats, however, are pro-
vided with an under- water exhaust With four-cycle engines,
it is usually customary to vent the exhaust piping at a point
considerably higher than tlie water-line, in order to prevent
water from siphoning back to the engine. Siphoning is
much more liable to take place with engines using positive
inlet valves than with those using automatic inlet valves,
for the reason that, when an engine of the four-cycle type
stops, the exhaust piping, muffler, and combustion chamber
are usually filled with hot gases and steam. These condense,
creating a partial vacuum, and if the exhaust valve is off its
seat, as it is on the exhaust stroke, and the inlet valve is
held to its seat, water from the exhaust pipe is liable to be
drawn into the cylinder or into the valve chamber, rusting
the exhaust- valve stem and thus causing it to stick. In a
two-cycle engine siphoning would not be so likely to occur,
because as the hot gases and steam condense and the exhaust
port is open, the passover port also would be open, thus
relieving the vacuum.

Mufflers should be piped so that the exhaust enters the
npper side or upper part of the end, leaving at the lower
end, and draining outboard, as shown at_/, Fig. 1.

1 7. One of the chief dangers from fire in boats propelled
by gasoline engines, whose exhaust piping is not water-
cooled, is from overheated exhausts. These fires are eaaly
discovered, and if the gasoline tanks are not located near the
exhaust piping, there is very little danger of burning up the
boat- In all cases the exhaust piping and muffler, unless
cooled, should be protected with sheets of asbestos board
securely bound on with wires or metal straps or some

108—18

16 MANAGEMENT OF §22

similar pipe covering. The exhaust pipe should extend |
inch or more through the planking, to prevent iron rust or
soot from staining the paint.

GASOLINE TANKS

18. The safest location for the gasoline tank g^ Fig. 1, is
in the bow of the boat in a water-tight compartment. Some
manufacturers make a practice of using a drip pan of liberal
height under the tank, connecting the two lower after comers
with the outside by means of scuppers or openings through
which it may drain when the drip pan is located above the
water-line; otherwise, means are provided for pumping
accumulations of water or gasoline from the water-tight com-
partment. Some objection may be made that the differ-
ence in weight of a full or empty tank affects the trim of
the boat, but this objection is trivial compared with the
advantage of safety. When tanks cannot be placed in the
bow, it is allowable to locate them on deck or in the cockpit,
in the open place in the stem, or under the seats. In both of
the last two places, the drip- pan system with outboard drain-
age should always be employed.

19. The material from which tanks are made differs
with their capacity. Tanks up to 40 or 50 gallons, made to

fit the contour of the boat and located
in the bow, or under the seats in the
cockpit, should be constructed of hot-
rolled or soft-rolled copper tinned on
the inside. For the larger sizes, no less
thickness than that weighing from 30
to 36 ounces to the square foot should
be employed; while for smaller sizes
of from 10 to 15 gallons capacity, 24-
ounce copper should be the lightest
^^°-^ allowable. The tanks should he

double-seamed, as shown at a. Fig. 9, on all edges except
the top, which may be a single seam, as shown at ^, both

§ 22 MARINE GAS ENGINES 17

seams being carefully soldered. Longitudinal and trans-
verse partitions, or svrasli plates, should be provided, so
that there may be in the tank no spaces larger than 12
inches in either length or width. Thus, for a tank 18 inches
wide and 4 feet 3 inches long, there should be one longitud-
inal and four transverse partitions.

The object of these partitions or swash plates is to prevent
the contents of the tank from rushing from end to end of the
tank and also to support, or stay, the sides and bottom. An
unobstructed movement or swashing of the gasoline would
be liable to dislocate the tank, break the gasoline piping or
tank connections, or stir up water or sediment that might
be present in the tank and cause a clogging of the car-
bureter or vaporizer. Even though the longitudinal parti-
tions may sometimes be omitted the transverse plates should
not be left out under any pretext. They should be riveted
to the bottom and sides of the tank, and, to prevent electro-
lysis in case salt water should ever be present, should be of
the same material as the remainder of the tank. Apertures
should be cut at the bottom to allow a free passage of the
contents from one compartment to another. The top of the
tank should be crowned slightly to prevent thy accumula-
tion of gasoline or water.

20. Before the top is put on, the connections should be
made for the gasoline supply and drain to the tank. Where
these connections are to be made, the sides should be rein-
forced by copper of the same thickness as the tank, project-
ing several inches above and to each side. These reinforcing
pieces should be riveted and soldered or sweated to the side
or the end of the tank rather than to the bottom. The supply-
pipe connection should be 2 or 3 inches higher than the drain-
pipe connection. The supply -pipe connection should be of not
less than j-inch iron-pipe size, seamless, soft-copper or brass
pipe, with two locknuts and washers — one nut and washer
on the inside and another on the outside — the whole
being sweated together with soft solder. The object of
thus soldering the connections is to prevent loosening

18 MANAGEMENT OP § 22

them in connecting or disconnecting the valve or supply
piping.

21, The gasoline tank and the drip pan should be con-
nected together rigidly, so that the tank will not slide around
in the drip pan. The supply pipe should pass through a stuf-
fingbox either at the top or at the bottom of the side of the
drip pan. There should also be a stufEngbox where the sup-
ply pipe passes through the hull in case outside piping is used,
or through the water-tight bulkhead in case it is decided to
use inside piping. All piping for gasoline should be of
ample proportions, never less than \ inch, preferably f inch,
iron-pipe size, and should be of soft, seamle;5S copper or
annealed brass, preferably the former; under no cir-
cumstances should lead or block-tin piping be used, because
of liability of leaks due to breaks caused by vibration.
With lead and tin piping there is also considerable uncer-
tainty as to whether or not the brass nipples used are sol-
dered properly. A screwed and soldered joint is much safer
than a plain soldered one.

Where the outside piping enters the boat, another stuffing-
box or similar contrivance should be employed. The suppl
pipe should enter as near the carbureter as practicable, an
between the carbureter and its entrance there should
interposed a helically wound coil to take up vibration an
prevent stress on the piping where it enters the boat^
Breakage at this point is accompanied with grave danger ^
and on this account the piping should at all times be pro —
tec ted against possible contact with ballast or anything liable
to injure or rupture it.

Stop-cocks should be placed close to the tank, and also
between the carbureter and the point where the piping"
enters the hull. Outside piping should be protected by ^
bronze shoe where it passes through the planking at the bow,
and with a grooved piece of oak put on with brass screws
and extending the whole length of the outside pipe.

33. Gasoline filling pipes and vents to the tanks are
very important features and frequently get little attention.

§23

MARINE GAS ENGINES

If the filling pipe extends several inches into the tank,
and small vent holes are drilled in it, as in Fig. 10, just
below the top, when filling with a long funnel that extends

coo

FlO. 10

Fio. 11

below these holes, air from the top of the tank displaced by
gasoline running in will escape through these small holes
and will not cause the gasoline to slop over. The filling pipe
may be made of lead and flanged over at the top, as in
Fig. 11, the whole being covered by a brass deck plate, or
cover, with screw plug.

23. The vent at the highest point of the tank should be
a piece of brass pipe extending into the tank several inches
and having two small holes as in the filling pipe. To this
pipe there should be screwed a brass T having at one end a
short nipple and check- valve to relieve pressure in the tank,
and at the other end another short nipple and check-valve
to relieve the partial vacuum in the tank caused by drawing
out the gasoline. This arrangement will be found more
satisfactory than drilling a pinhole in the plug, or using a
loosely fitting screw to relieve pressure or vacuum. Under
no circumstances should pressure be applied to the tank to
cause gasoline to run to the carbureter.

20 MANAGEMENT OP § 22

24. It is sometimes convenient to use copper or galvan-
ized-iron kitchen boilers instead of rectangular tanks.
Unless they are especially made and have partitions in them,
such boilers should be as short as possible. If they have no
partitions, they should preferably be set on end. If they
have to be placed in a horizonal position, they should be
solidly and carefully blocked and secured, to prevent them
from moving and breaking the gasoline-supply connections
or piping.

When large quantities of gasoline are to be carried, the
tanks should be built like steel steam boilers, with the neces-
sary swash plates riveted and calked, and as a f lurther pre-
caution they should if possible be galvanized inside and out
Cylindrical tanks are preferable to rectangular tanks, and
should be employed where there is sufficient room.

In case it should be necessary to locate the tank on deck,
the inside of the wooden covering, or hatch, should be
lined with asbestos or some other non-conductor of heat
In any case, the same system of drip pan, vents, etc should
be employed, except that for filling purposes a removable
hatch may be used if desired, but care should be exercised
in tilling the tank not to allow it to run over.

25. If the engine is to be operated from some part of
the boat other than at the engine, the various controlling
devices should be attached and tested to see that they work
properly. From whatever point the engine may be handled,
a connection must be made so that the gasoline supply may
tK.* shut off every time the engine is stopped.

S 22

MARINE GAS ENGINES

MARIKE-ENGINE OPERATION

STABTrKTG, RUNNING, AND STOPPING

26. When an engine is about to be started it is not safe
to assume that all the adjustments are correct, just as they
were when the engine left the shop, and only by careful
examination can the operator be sure that the engine is
ready for use. The following general rules may be applied
whether the engine is of the two-cycle or the four-cycle type,
either single cylinder or multicylinder.

First, determine which way the engine runs normally,
whether right-handed or left-handed. When facing the fly-
wheel and looking toward the stem of the boat, if the direction
of rotation of the flywheel when the boat is going ahead is

(b)

Pig. 12

the same as that of the hands of a watch, as shown by the
arrow in Fig* 12 («), the engine is a right-hand engine and
requires a left-hand propeller wheel to drive the boat ahead.
When the movement of the flywheel is contrary to the direc-
tion of movement of the wat^h hands, as in Fig. 12 (^), the
engine is a left-hand engine and requires a right-hand

22 MANAGEMENT OF § 22

propeller wheel in order to propel the boat ahead. When
turning it over rotate the flywheel in its proper direction with
the cocks open, or with the compression otherwise relieved.
Determine when the piston is on the upper dead center, and
make a mark on the flywheel in case the starting pin that
fits into the hole «, Fig. 12 {a) and (^), is not where the mark
would come. If there is no starting pin, or if it should be
set at a point 90** from the upper dead center, mark the fly-
wheel plainly to indicate when the piston is on the upper
center, another mark being made on the opposite side of fly-
wheel to show when the piston is exactly on the lower cen-
ter. If the starting pin in the flywheel is set 90° from
the upper center, its position should be changed to corre-
spond with the mark made to show when the piston is on
the upper center. Any other location for the starting pin is
dangerous, giving rise to broken and sprained thumbs, wrists,
and arms, besides other injuries.

Having marked the flywheel to show the position of the
piston in the cylinder, then, with the gasoline turned off
and the battery switch closed, turn the flywheel slowly until,
if a jump spark is used, the spark coil begins to buzz, where-
upon another mark should be made on the flywheel. If the
make-and-break system of ignition is employed, note where
contact is made and where it is broken when the spark occurs.
If the engine is of a multicylinder type, try each cylinder
separately, to determine whether or not the contact is made
at the same relative position for all cylinders and that the
spark occurs at the same point before or after the center is
passed.

37. If the engine is of the two-cycle type using jump-
spark ignition or the usual form of make-and-break ignition,
which will allow it to nm in either direction, turn the flywheel
in the opposite direction until the mark shows it to be about 30°
before the upper center. Then, advance or retard the spark
until a contact is made just at that point, and note the p)osi-
tion of the spark-control lever. If the engine is of the single-
cylinder, two-cycle type, the easiest method of starting the

g2'3

MARINE GAS ENGINES

33 '

engine is to prime the combustion chamber bj- injecting a few
drops of gasoline into the priming cup with a squirt can, and
turn on the gasoline supply in case a carbureter is used, prim-
ing it also by depressing the float; if, however, a vaporizer is
used, set the needle valve at the point usually made on the
dial when the engine is tested, swing the flywheel several
times slowly back and forth through a space equal to about
one-third the circumference, and then, takingfirmholdof the
starting pin, swing it up smartly against the compression in a
direction opposite to its normal rotation, and then let go.
If the engine does not start after trying this two or three
times, first close the valve in the gasoline supply, open the
relief cock, and turn the engine over three or four times, and
note whether or not explosions occur. The relief cocks should
be open and the spark lever set so that ignition will occur
either just after the center is passed or as near the end of the
up stroke as possible.

88. In two-cycle engines using make-and-break ignition
that will run in either direction, motion is given to the
igniter or movable electrode by means of an eccentric
securely fastened to the crank-shaft or hub of the flywheel.
The high part of the eccentric is either in !ine with the crank-
pin or directly opposite, usually the former. Reference to
Fig. 13 will make it clear that the eccentric carries the rod
that moves the igniter upwards during
/^- — V \ one-half of the revolution of the crank-
/ \ \ shaft and downwards during tlie other

Y J \ half. The tripper must therefore act

^ — -^ ] before the extreme top or bottom center
is reached, no matter ia which direction
the crank-shaft turns. In engines de-
signed to run in but one direction, this
' '"■ "* is a comparatively simple matter, for the

eccentric can be secured bo that it will not arrive at its high-
est point until after the upper center is passed. This is true
also of nearly all four-cycle engines; for, unless they are
designed to run both ways, the action of the ignition cam

24 MANAGEMENT OF § 22

is retarded, and if designed to run both ways, separate
cams for ignition, as well as valve operation, are always
employed.

29. Fig. 14 shows a method of arriving at a solution of
the problem of igniting the charge before or after the upper
center is passed. An eccentric that is not keyed to the shaft

Pio. 14 Fig. 16

is provided with a pin that projects through a curved slot in
the web of the flywheel; and, by fastening the pin to one
side or the other of the middle of the slot, the ignition will
be delayed or advanced when the engine is running in either
of the directions indicated by the arrows just above the slot
Another method employed is to have in the eccentric a
slot wider than the key that fastens the flywheel, the key
extending into the keyway in the eccentric, as shown in
Fig. 15, the eccentric being mounted loosely on the flywheel
shaft, as in Fig. 14.

30. Fig. 16 shows a double motion used by another manu-
facturer to obtain the same result. In this figure, a is the
crank-shaft; *, the eccentric; r, the eccentric rod, or strap,
pivoted at d in the slot^. The position shown would not
allow the pin f^ which is raised by the forked end <rf the
eccentric rod c, to trip and separate the electrodes until a
considerable time after the center had been passed; but, if
the eccentric h were turning in the direction indicated by
the arrow, and tlie eccentric rcid c were held to the left, it

MARINE GAS ENGINES

would trip earlier, or at such a time in the upward motion as
desired, this time being regfulated by the amount the rod is
held to the left, which is controlled by means of the hand
lever k. If the reverse motion
is given to the eccentric, the eccen-
tric rod would give the same time
of ignition, provided it were held
at the same relative position to the
right, instead of to the left.

31. Multicylinder two-cycle
engines, unless they have some /
such means as described for re-
tarding the spark, if designed to
run in both directions, are ex-
tremely dangerous to start and
very much more so if they are
provided with a starting pin in the
flywheel. Every owner of a mul-
ticylinder marine engine should
remove the starting pin, if one is
used, just as soon as possible; if
left in, it may cause serious injurj'.

A multicylinder two-cycle en-
gine should never be started in
the same manner as is usual with
single-cylinder two-cycle engines, nor should the attempt
to do so ever be made. It is very important that this
should be remembered; if any one should attempt to start
a multi-cylinder two-cycle engine by rocking the flywheel
back and forth, as is customary with single-cylinder two*
cycle engines, and tliere happened to be a charge of gas
left in any of the cylinders, the ignition of such charge
might cause a serious accident, many persons having been
injured in this manner.

3S> In four-cycle engines, the une of a starting pin is
unnecessary and even more dangerous than with two-cycle
engines, for the result would bo just as bad if an explosion

MANAGEMENT OF

§22

should take place and the engine were to start ahead as it
would if a back kick occurred and the operator did not let
go of the starting pin in time. . Starting pins are unneces-
sary, engines without them being provided with flywheels
of larger diameter so as to be more easily grasped by the
operator.

Small sizes of four-cycle engines with flywheels on the
forward end of the crank-shafts are usually started by grasp-
ing the flywheel, although some are designed to use a starting
crank that automatically releases as soon as the engine
starts. .

Fig. it

33. If a starting crank is used, it is manifestly easier to

start a marine engine that nms right-handed than one that

runs left-handed. For this reason, nearly all
marine engines that are crank-started, are
right-handed. The starting crank usually
hooks over a pin in the end of the crank-shaft,
as in Fig. 17, or over the end of the key hold-
ing the fl}n^-heel in place, in w^hich case a
left-handed crank should be used to run the

engine left-handed, or a right-handed crank to run it right-
handed.

The pin should so engage the starting crank that the

engine \Nnll pass the upper center at a point about 45^ before

the starting crank reaches the center, as

in Fig. 18. In this case, to start an engine

lett-handcii on the compression stroke,

the crank-handle would describe one-half '/

a circumterenoe. d-ti-t/^ or 1S«»^^: while, if *

riiiht -handed, it would be ii-^'. The

n\ovo:r.oni v>! the crank-handle should

aiwavs Iv iii^warcs. the oh^ect beinij to

*•/.: ;::> ^^ti the h.\r.v;'.c when the irreatest

>.>-->-,-« -y^^ charge, and when on^^

.V . V V.

V. ».

c»

tv^ v>"'

:r.-y;e:e the halt-turn mov'^
■ :^o.v< :,:r.*::.^" is employed. Suppc:*^
vo 'x-or. .i.lvAr.cOvi to a point/. Fig. ^^

§ 22 MARINE GAS ENGINES 8?

and that at this point the electrodes were in contact^ if
the force exerted to compress the charge were removed,
the handle might go back to, say, e^ when, M the Electrodes
were to separate, a spark w^onld occur and a back kick
would result. On the other hand, if the crank were to be
carried to r, or were to pass it, the piston being thereby
carried beyond the upper dead center, the expansion of the
compressed charge would carry the piston part way down
until the igniter would trip and ignite the charge, and
motion would be given to the crank-shaft in the proper
direction. Sometimes the crank-handle describes the half
circle g-h-e^ or e-h-g^ but it is better and safer when the
path of travel is a-b-c or b-a-d. No matter where the
crank-handle path is located, if for any reason the operator
is tmable to get the piston past the upper center, and
make-and-break ignition is used, there is danger of back
kicks.

34, Instead of a pin through the shaft, a ratchet wheel
of one, two, four, or more teeth is sometimes keyed to the
shaft. A single tooth is much safer than two or four teeth,
more than two teeth being unnecessary as well as unsafe.
If a two- toothed ratchet is used, the crank -handle should
describe the arcs a-b-c or b-a-d^ also c-d-a or d-c-b.

In three-cylinder engines having cranks set 120** apart, a
three-toothed ratchet should be employed. If a pin is used
in the crank-shaft, it should not extend through, as in
Pis'- 17, but in the starting crank there should be three
hooks 120** apart, to give the same relative motion in com-
pressing and exploding the charge in each cylinder.

Where the engine is too large to start by ordinary means,
various mechanical devices are employed. Some of tliem
are more dangerous than others, and any one of tlaem in
the hands of an inexperienced person may cause injury to
the operator or others.

35. Fig. 19 shows one meth<^ of using a starting bar.
The flywheel for a single-, double-, or four-cylinder engine
usually has four cored apertures, arranged 00** apart, with

MANAGEMENT OF

a and 6 usually 45'' ahead and back of the upper center,
respectively, and with c and d diametrically opposite a
and b. There are two rows of these if the engine is
designed to be run in both directions. In right-handed

Pio. 10

action, the lever has a toe e that comes against the side g,
with the heel /against A. As soon as the engine starts, the
lever is easily withdrawn; this is, perhaps, the simplest
starting-bar system.

Another starting bar, the construction of which is shown in
Fig. 20, consists of a toothed ratchet a, with a yoked bar t,
and a pawl c engaging the teeth of the ratchet The teeth
are usually hooked more or less, and if the engine is to be
run in both directions, it is necessary to have two ratchets
and one pawl, turning the forked lever half way around to
run in the opposite direction. In this case, as in using
starting cranks, it is necessary to see that the explosion does
not take place too early, or it may result in injury to the
arm.

36. Frequently, in using a crank in close quarters, it is
customary to bend it just above the pawl, so that the handle

^22

MARINE GAS ENGINES

will lead to a point about 45° from the crankpin. This will

make it possible to get a hold lower down. If there are

tnoTe than four teeth the same danger exists as in the case

of more than two teeth to the

starting crank. If the engine

is not too large to start without

relieving the compression, the

utmost care should be exercised

in starting the engine, and the

use of a four-toothed ratchet

should be discouraged.

37* If the engine is one in
which the compression must be
relieved in order to start, almost
any one with a little ingenuity can
arrange an attachment whereby
the compression may be relieved
and the spark retarded at the same
time. Fig. 21 shows how this
may be done; ^, a\ and a" are
three cylinders having relief cocks
i, d\ and 6" connected through a suitable rod to a bell-crank
lever c pivoted at d. In the position shown, the relief cocks
are open. Suppose, now, that they are in closed position.

Pig. 90

Fig. 21

as indicated in Fig. 22, and that a rod r, passing through
a pivoted stud in the spark lever, is provided with collars /
and £" held in place by setscrews or other means, the rod e

30 MANAGEMENT OP § 22

sliding through the guide i until the relief cocks are open, or
nearly so, before the collar g moves to a point where the
spark lever indicates that the ignition is in late position. As

®ir 0j

PIO.82

the engine starts, the e rod can be drawn back until the
collar f engages the spark lever and advances the spark as
the compression relief cocks are closed.

In the case of a four-cycle engine having a cam-shaft with
an endwise movement to bring a double-lipped exhaust cam
into operation to relieve the compression, the same shaft
can also bring into operation another cam to control the
ignition. There are many ways to accomplish this object,
and, on accoimt of securing greater ease of operation, it is
suggested that all owners of gasoline marine engines should
study out some way to make a connection between the com-
pression relief and spark control

38. One means of relieving the compression, used only
in four-cycle engines, consists in having the exhaust valve
open during a part of each compression stroke; while
another consists in using cylinder relief cocks screwed into
openings either through the cylinder walls and covered by
the piston when near the end of the up-stroke, or into open-
ings communicating directly \inth the combustion space
above the top of the piston. Compression cocks are neces-
Svirily employed in two-cycle engines, and because of their
cheapness they are finding favor among manufacturers of
f,x:r-cycle engines. There is, however, an element of
danger associated with their use, as many boats that have

MARINE GAS ENGINES

been burned would not have tiiken fire except throngh relief
cocks. When used iu cabin boats, the relief cocks should
be piped outboard or into the exhaust, for, if there should
be present in the boat's cabin or under the floor gasoline
vapor and air in the proportions of an explosive mixture,
with the relief cock open and shooting a column of flame
down toward this mixture, an explosion might result that
would destroy the boat. If compression relief cocks are
used, they should, therefore, always point upwards instead
of downwards. Combined relief and priming cocks can
often be used for priming the cylinders, but separate prim-
ing cups should always be used where the engine is installed
in a cabin.

39. Starting an engine having no reversing gear, but
v/itb a reversing propeller, is somewhat easier than to start
with a propeller connected rigidly to the propeller shaft, the

'^egT^'ered blades of a reversing propeller acting to relieve the
engine of nearlyits full load, while a solid propeller and shaft
carry a full load. In the latter case, no governor is required.
In order to nm the boat astern with an ordinary two-cycle
engine, the engine is stopped and run in the opposite direction.
As this is impractical with four-cycle engines, governors are
quite necessary in all reversing-gear engines of more than (i
or 8 horsepower, although some makers do not use them at
all, or not until the engine reaches from 10 to 20 horsepower.
In case no governor is used, great care should be exercised
to prevent the engine from running away. As governors
sometimes fail to act, it is always better, when starting an
engine, to have the throttle within easy reach, as well as
the switch, in order to prevent an accident If the engine
has an auxiliary air supply, as many four-cycle engines do.
it is usually closed on attempting to start, as it is better to
have the mixture a little too rich than a little too poor in
gasoline vapor.

40. Before starting a four-cycle engine, the operator
should be satisfied that the inlet and exhaust valves, as also

q>ark, are correctly timed, that the adjustments are

32 MANAGEMENT OF §22

correct, that the valves all seat properly, and that they are
not rusted or stuck in their guides. A drop or two of kero-
sene oil should be used occasionally on the valve stems. Be
sure that all the oil cups are filled, that all moving parts are
properly lubricated, that the sea cock is open, and that there
is nothing to prevent the free passage of water through the
cylinder water-jackets and thence outboard. Look out for
ropes that may be wound up by the propeller ; a few acci-
dents from this cause will usually teach caution as nothing
else will. Make sure that the electric-ignition system is in
good working order by testing it with the current on, if of
the make-and-break type, or by the buzzing at the spark
coil if jump-spark ignition is used. Next open the relief
cocks or push the relief cams into position, turn on the gaso-
line and see that it runs freely, and turn the engine over
two or three times as fast as convenient. To facilitate start-
ing, it is sometimes better to put a little gasoline into each
cylinder through the priming cocks. This operation is
called priming. After two or three devolutions, the engine
should start, when the relief cocks should be closed or the
relief cams thrown out, and the speed of the engine regu-
lated by the throttle, the proportions of the mixture being
regulated by the auxiliary air valv^e or by the needle in the
gasoline valve, unless a compensating or other form of car-
bureter is used. If the engine misses explosions, it may be
that it is throttled too much, but it is more probable that
the mixture is too rich in gasoline vapor. If the engine
begins to slow down, give it a little more gasoline, and if
that does not remedy matters decrease the amount, or
increase or decrease the amount of auxiliary air. When the
engine is running satisfactorily, open the oil cups and see
that they feed properly and that the jump operates, watch-
ing, of course, for overheated bearings, as in any new piece
of machinery.

41. If the engine is directly connected to the propeller,
there is nothing else to be done except to get the propor-
tions of air and i^asolinc vapor as nearly right as possible,

§ 22 MARINE GAS ENGINES 33

see that lubrication is constant, and that the circulating
water discharges freely. If the engine has a reversing gear,
there will be little need of throttling when changing from
full speed ahead to a neutral position or full speed astern;
but with a reversing gear and no governor, extreme care
should be exercised in throwing in either gear or the engine
may be stopped. The reversing gear absorbs some part of
the power of the engine, which is more liable to stop when
attempting to go astern than ahead. It will be necessary,
in case a governor is not used, to have some practice in
order to be sure that the engine will not be stopped when
throwing in the gears, and in order to be able to handle the
throttle properly. With a governor, however, the manipu-
lation of the engine is largely a question of properly propor-
tioning the mixture of air and gasoline vapor and of proper
adjustment

43. Once started and running, the engine may not turn
up to its usual speed, may miss explosions, or may seem to
labor hard. In such cases, an examination should be made
to see that the lubrication is sufficient and regular, remem-
bering that a little too much lubrication is not so bad as
too little, although an excess of oil in the cylinder may give
trouble later. As the effect of too much oil is indicated by
the color of the exhaust, trouble from this source is easily
discovered and can easily be remedied.

An attempt should first be made to remedy the trouble,
if possible, by varying the proportions of the mixture of air
and gasoline vapor. Then, the electrical connections should
be examined carefully to see if they are tight. If conditions
seem to get worse instead of better, it will be necessary to
stop the engine and search out the trouble, for it would be
imprudent and possibly dangerous to continue running.

43. When the engine is to be stopped, first throw in the
compression relief cam or open the relief cocks. The object
of relieving the compression is to prevent the engine from
running after 'the electric current is thrown off, the mixture
remaining in the cylinders igniting from incandescent

34 MANAGEMENT OF § 22

particles of carbon attached to the piston or walls of the
cylinder. The switch should then be thrown out and the oil
cups shut off. When using reversing gears, it is always better
to stop in the neutral position, neither going ahead nor astern,
for it is usually much easier to release a clutch when the
engine is running than after it has been stopped. The
gasoline-supply valve, which should always be placed in the
supply pipe directly back of the vaporizer or carbureter,
should then be closed.

Among several reasons for adopting this method of pro-
cedure when stopping an engine the following may be men-
tioned: If the engine is stopped by entirely closing the
throttle, its closed position may not be noticed when
attempting to start, and with the throttle closed the cylinder
will be filled with a charge of burned gas instead of a fresh
charge of explosive mixture ; the engfine should not be stopped
with the switch on and the make-and-break electrodes in
contact, as the batteries would thus soon be exhausted.

Shutting off the gasoline at the vaporizer by means of the
needle valve is extremely bad practice. It is much better
and more sat isf actor}- to close the valve or cock in the sup-
ply pipe, for should a leak develop at the union in the
piping to the carbureter the closing of the needle valve
would not prevent gasoline from leaking into the lower
jviirt of the Ixxit. Shutting off the supply at the vaporizer
in twHvcycle engines is more likely to cause crank-case
cxpKvidons or Ivick fires than in four-cycle engines. Back
firing is caused by a too weak mixture of vapor and air,
which is slow-buniing. In four-cycle engines, more time
elapses Knwccn the opening of the exhaust and the inlet
valves than in two-cycle engines, in which the inlet port is
oiviuxl almv>s: at the same time as the exhaust. The faster
the twv^-cvc'o or.cir.e nir.s, the less time there is between
tV.o oix^r.ir.vc v :* :ho twv^ iv^rts and the greater the liability to

x»«-»»* **C-^ »^X*> '*C' ^"'^ "*- 'X' ^.■" •» •■^ »* ,"~

some coerat OTS are

This is Tir.necessarv

§ 22 MARINE GAS ENGINES 85

and is liable to cause more harm than good ; for, were the
engine to be started with the sea cock closed, considerable
damage to the engine might be caused by overheating.
Rubber hose should not be used for the connection from the
pump to the sea cock, and if suitable piping is here used
there is little if any danger from a leak developing while
the engine is not running.

As a precautionary measure, it is always good practice to
close the gasoline valve at the tank at the same time it is
closed at the vaporizer or carbureter.

CABi: AND REPAIR OF ENGINE

CARB OF ENGIXE

46. The proper care of an engine and its auxiliaries
depends largely on the character of the engine. When an
engine is exposed to the action of salt water that fre-
quently comes aboard as spray, it requires more care than
when installed under cover. While the exterior of an
engine should always be kept clean, this is not so essential
as that all bearings and moving parts be kept free from rust,
gummed oil, and dirt, and that the lubricating system may
be depended on when the engine is running. Loose bear-
ings should be remedied promptly, all bolts and nuts should
be examined frequently, replaced if lost, tightened if loose,
and where holes are drilled in the ends for spring cotters,
the latter, if not in place, should be replaced. To avoid
possible trouble with the gasoline supply and carburization^
gasoline tanks and piping should be inspected occasionally
for accumulations of water and dirt. The carbureter or
vaporizer should be looked after, and the lubricator sight-
feed glasses, if clouded so that the feed cannot be seen
plainly, should be cleaned with kerosene or gasoline.

Salt water injures machinery, and should by all means be
kept from the -reversing gear or clutch ; for, in addition to
its oxidizing effect, the presence of dissimilar metals in the

36 MANAGEMENT OF §22

salt water gives rise to electrolysis, which is very destructive
to studs, bolts, gears, shafts, etc.

In cold weather, the water should be carefully drained
from the water-jacket, pump, and piping, to prevent it from
freezing and thus bursting the water-jacket. While burst
piping can readily be replaced, it is not an easy matter,
even when possible, to repair a broken water-jacket, or
even to replace a pump.

Lubrication of the reverse gearing, clutches, and thrust
or spring bearings should not be forgotten. The stem bear-
ing is lubricated by the water, while stuffingboxes are lubri-
cated by the flax packing, which is usually filled with tallow
or some similar substance.

Kerosene will be found very convenient to use in loosen-
ing gummed oil on bearings and even in the cylinder it may
be used freely to loosen up accumulations of carbon and
burned oil. In fact, kerosene is a necessity for occa-
sional use on valve stems in four-stroke engines or on the
movable igniter bearings in engines using make-and-break
ignition. A little vaseline or cylinder oil ma)' be used to
coat bright parts to prevent them from tarnishing, but the
former is much cleaner than the latter. Special care should
be exercised to see that sufficient supplies are always on
board — aplenty of gasoline, oil, tools, a good reserve battery,
always a pail to use in case of fire or a bad leak, a dry-
powder fire-extinguisher to put out possible gasoline fire,
and a life preserver for each person on board, for personal
safety is of the greatest importance.

LAYING IP THK KNGINE

46. In leaving the engine after a run, the gasoline
should always be shut off at the tank, and also at the
valve near the carbureter or vaporizer. The lubricators
should be closed, and any excess of oil on the engine
wiped off while the engine is warm. If cold weather i^
threatened, drain the water-jacket, pump, and piping, a^d
cover the engine with canvas, being careful that it does

§ 22 MARINE GAS ENGINES 37

not touch an over-heated exhaust pipe, where it is liable to
take fire.

When the season is over, and the boat is ready to lay up
for the winter or the closed season, the engine should be
taken out of the boat if convenient. If not it should be cleaned
carefully and the bright parts covered with vaseline, white
lead and tallow, or something that will protect the parts and
still be easily removable. Plenty of cylinder oil should be
left in the cylinder, the flywheel should be turned over two
or three times, the piston being left on the outer center to
prevent any possible rusting of the upper surface of the
cylinder, where it is quite important that there should be
a smooth surface. A multiple-cylinder engine should be
turned over occasionally to guard against similar trouble.
If the engine is to be left in the boat, it should be protected
with a water-tight covering, no part of which should be
allowed to touch the engine, as such contact is very sure to
cause rusting.

If these precautions are carefully observed, very little
trouble should be experienced in putting the engfine in com-
mission at the beginning of the season. It may be well to
remove a large part of the oil put in when the boat was laid up;
the engine should then be as easy to start as when put away.

TOOLS AND REPAIR PARTS

47. A few tools are always necessary in running a
marine gas engine to get at or remove parts that may have to
be taken down for adjustment, repair, or inspection. A
pipe wrench is indispensable, also a good-sized adjustable
monkey wrench (say about a 14-inch), a small and a large
screwdriver, pair of adjustable hawk-bill plyers, bicycle
wrench, three-cornered and half-round second-cut or bastard
files, 8 and 10 inches long, respectively, light round peen
hammer, {^-inch cape chisel, two or three cold chisels of
diflEerent lengths, a center punch, a small round nail set, and
such other small tools as may be useful in case of emergency.
The tools liable to rust can be carried conveniently in a

38 MANAGEMENT OF § 22

waterproofed canvas roll, where they may be found when
they are required; but the pliers, on account of their fre-
quent use, might better be carried in the pocket. One of
the most convenient tools on board a boat is a small hand
vise, similar to those used by electric linemen. It will hold
almost an3rthing it may be desired to file, and Tvhile not
absolutely necessary will often be found a convenience.

Tools are of little use unless there is at hand an assort-
ment of supplies, including shellac, strong cotton cloth,
insulated wire, soft copper wire, hard bronze spring wire of
different sizes, insulating tape, some strong cord, small
pieces of canvas, some soft sheet brass or copper .003 or
.005 inch thick, and, if possible, a roll of gasket material in
a water-tight tin box to prevent it from becoming wet or
broken. An assortment of nuts, cotter pins, etc., as well as
duplicate small parts liable to become broken, such as igniter
springs, could be carried in a spice box to obviate a serious
breakdown.

MANAGEMENT OF STATIONARY

GAS ENGINES

INSTALLATION

SELECTION OF ENGINE

POINTS GOVERNING SELECTION

!• In selecting a stationary gas engine there are sev-
eral important points to be considered, and the engine that
embodies the greatest number of desirable qualities is the
one to be preferred. First of all, the engine must possess
sufficient capacity to accomplish the desired work. It
must also be adapted to the requirements of speed, regula-
tion, and direction of running imposed by the work to be
done. It should be economical in fuel consumption, relia-
ble in service, and of simple construction.

2, In determining the size of an engine for a given
amount of work, it should be borne in mind that an engine
that is called upon to run at its full capacity during the
greater part of the time is actually overtaxed. Working an
engine to this extent will result in rapid wearing of the
cylinder and piston, and consequent loss of power and
economy due to leakage. When doing the maximum
amount of work possible in a plant, the engine, if
governed by the regulation of the number of impulses,
should cut oflE at least once in four or five charging strokes.
This will benefit the cylinder through the admission of
charges of pure cool air at more or less regular intervals.

CopffigkUdhy Iniemaiknai Textbook Company, Entered at Stationers* Halt, London.

188

2 MANAGEMENT OF § 23

3. The type of engine decided on should be the one
most suitable for the work it is to do. Engines for opera-
ting electric generators, especially for lighting purposes^
must run with greater steadiness than is generally required
for ordinary power. There are other cases — such as the
operation of sensitive typesetting machines — where a very
steady speed is desirable. The question whether a horizon-
tal or a vertical engine should be selected must be settled
with a view to local conditions of available space and the
character of the work ^o be done.

4. The consumption of fuel should always be in propor-
tion to the work performed by the engine. The g'ovemor
should respond promptly to any fluctuation in the load, and
the friction loss should be kept at a minimum by proper
methods of lubrication. The attainment of good results
depends largely on careful workmanship, as well as on prop-
erly proportioned valves and liberal bearing surfaces.

6. The engine should be capable of being started
promptly without great exertion, of developing its rated
horsepower, and maintaining a steady speed, while con-
suming the normal amount of fuel.

6. Other things being equal, the engine that is simplest
in construction and operation is to be preferred. This,
however, should not be carried to a point where reliability
of running and accessibility of the working parts are sacri-
ficed. All the working parts, such as piston, connecting-
rod, valve gear, igniter, etc., should be in plain view and
easy of access for cleaning and necessary repairs.

EXAMINATION OF ENGINB

7. Even a casual inspection will reveal to the eye of a
mechanic certain evidences of good or bad workmanship.
Among the points that should be observed are the condi-
tion of the threads and the fitting of the nuts and their
wrenches. Threads should be full and smooth, and the

§ 23 STATIONARY GAS ENGINES 3

nuts should fit so as to enable them to be turned by hand on
the studs or bolts, although they should fit snugly — that is,
-without play. The jaws of the wrenches should fit the
nuts exactly. The fit of pins, levers, or links can be
inspected by moving them by hand, when they should
slide smoothly and evenly. Whenever possible, moWng
parts subject to wear should be properly hardened to a
moderate depth below the outer surface. This refers espe-
cially to cams, rollers, blades, and pivot pins.

8. When in motion, the good workmanship of an engine
is indicated by smooth and noiseless running. There should
be no pounding or clattering sound, which would indicate
lost motion and loose-fitting bearings or piston.- The fly-
wheels should run true and without vibration. If the rim
of the wheel should show any vibrating motion at the time
of the explosion, it would be evidence of weakness either
in the crank-shaft or in the wheel itself. The proper balance
of the revolving and reciprocating parts is indicated by the
absence of any forward and backward sliding of the engine
bed on its base or foundation.

9. When the engine is operated with illuminating gas,
the consumption of fuel is best determined by reading the
meter at the beginning and at the end of a certain period of
time while the engine is running under its rated load. As a
rule, manufacturers guarantee the power and the gas con-
sumption per brake horsepower under full and partial loads.
A gasoline engine should be tested as to its fuel consumption
by connecting the pump to a graduated bottle of about
1 gallon capacity, and the amount used for a certain period
should be noted. A good engine, running with ordinary
stove gasoline, should use about a pint of fuel per brake
horsepower per hour when running under its rated load.

10. Before deciding on the make and type of engine
contemplated for a certain purpose, it will always pay to
investigate the working of engines of the same manufac-
ture that have been in use for a reasonable length of

4 MANAGEMENT OF § 23

time. Reports from reliable users will go far towards deter-
mining the actual merits of an engine, its economy, the
amount of repairs it may be expected to require, and other
matters of vital interest to the power user.

ERECTING THE ENGINE

LOCATION OF ENGINB

!!• The selection of the most suitable location for an
engine deserves careful consideration. The space to be
occupied by the engine should, if at all possible, be sepa-
rated from the rest of the room by a partition. Sufficient
space should be allowed around the engine, especially on
the valve and governor side, where the space should be not
less than 3 feet, to permit of easy access to any part of the
engine. In all factories or shops where the presence of fly-
ing d\ist IS unavoidable, it is necessary that the engine room
should be surrounded with dust-proof walls. A room
well lighted and ventilated is a great help in keeping the
engine in proper condition, since it allows the attendant to
watch closely the lubrication, valve motion, action of the
go\'cmor, etc. The \ise of an open belt is always preferable
to a crossed belt running from the engine to the line shaft
The engine should be set in relation to the direction in
which the shafting or machines to be driven will revoh^,
and the question of open or crossed belt should be decided
with this point in \new. The distance between the centers
of the engine shaft and the line shaft or the machine to be
openiteil should never be less than 10 feet for engines up to
10 horsepower, and from 1*2 to *20 feet for engines of larger
siie*

Ft>rNI>AT10X

fi. Fonndatlon Templet. — The location of the engine
hav!!*^ K^ev. v'otcrr.'.inov:. the fv^v.ndation may be prepared.
r'.»i!::> .iv.vl sixvinc^itior.s ^l\-i::ir the size, depth, and material

S'-i:i STATIONARY GAS ENGINES 5

of the foundation are usually supplied by the builders of the
engine, and in many cases a templet is also provided by them.
This templet is a rigid framework, made of 1-or l^inch
boards from i to 6 inches wide, in which holes are bored cor-
responding to the holes in the engine bed through which the
Itoldlng-do'svn, or fbtuitlatlon, bolts-must pass. If the
templet is not pronded by the maker of the engine, it should
be constructed in accordance with the dimensions given on
the foundation drawing. If the engine bed is at hand, it is
well to measure the distances between bolt holes, and com-
pare these distances with those shown on the drawing. If
they do not agree, as is sometimes the case, the holes in the
templet should be located by measurements taken from the
engine bed. The engine builders often furnish the founda-
tion bolts, nuts, washers, and anchor plates.

The center lines of the cylinder and crank-shaft should be
marked on the templet with a scriber. In setting the tem-
plet, care ehotild be exercised to have it the required height
from the floor, level on top, and square with the building.
This is done because the templet is tosed to determine the
height of the top of the foundation bolts as well as their posi-
tion laterally. If the shafting to be driven is in place, the
center line of the crank-shaft as marked on the templet must
be brought parallel with that of the line shaft To accomplish
this, drop two strings with weights attached, one on each
side of the foundation and several feet away from it, from
the line shaft to the floor. Then set the templet so that a
string drawn across it, and exactly in line with the center line
of the crank-shaft, is the same distance away from the two
plumb-lines suspended from the line shaft. The crank-shaft
will then be parallel with the line shaft, so that they may be
connected by pulleys and belt.

13. Placing Ponndatlon Bolts. — After the templet has
been set and securely propped up and fixed in position, the
foundation bolts should be inserted, allowing the top ends to
extend the proper distance above the boHom of the templet.
nMnp.ttbft aiU»^«i)d wa^iera are in place, ao that tiie enda of

r» MANAGEMENT OF §23

bolts project slightly beyond the nuts, the distance above
the bottom of the templet should be adjusted so that it will
equal the distance that the bolts should project above the
top of the foundation.

In order to guard against any slight shifting of the foun-
dation bolts while the masonry is being put in place, or
against discrepancies between the foundation plan and the
engine bed, it is advisable to surround the bolts with wooden
casings or, preferably, with iron pipes about 1 inch larger
on the inside than the diameter of the bolts. This will per-
mit the bolts to be moved slightly in the fotmdation and
their location to be adjusted to suit the actual measurements
of the engine bed.

14. Boildlngr tlie Fotmdation. — ^The building of the
foundation may now be undertaken. If brick is used,
it should be of the hard-burnt quality, and should be laid
in mortar made from a good quality of Portland cement and
clean, sharp building sand, with a sufficient amount of water
to render the mortar of the proper consistency. Common
brick or building stone may be used for the inside of the
foundation, but the outside should be faced with pressed
brick.

In many cases, a foundation of concrete is cheaper or more
convenient to construct than one of brick or stone, and, if built
of a proper grade of material, is preferable to a brick founda-
tion. A good mixture of concrete may be made of five parts,
by volume, of broken stone, about 1^ inches in size, two parts
of clean, sharp sand, and one part of Portland cement, adding
water in proper quantity and thoroughly mixing the material
to jri\'e it the required consistency. After the pit has been
filled with concrete up to the floor level, build or place a box
under the templet, the inside measurements of which should
correspond with the size of the part of the foundation that
projects above the floor. Pill the box with concrete, and do
not remove it until the mixture has become well dried, which
^ijcnerally requires from 3 to 4 da\*s. After the box has been
ro moved, the sides and top of the foundation should be

§i3 STATIONARV GAS KNGINKS 7

finished with cement mortar, so as to give it a smootb
appearance. The templet should not be removed until the
foundation has completely dried, as there is danger of the
bolts being drawn out of their proper position during
the setting of the foundation,

A properly built concrete foundation becomes as hard as a
solid mass of stone. Brick foundations for large engines
should, if possible, be topped with a cap of sandstone or similar
material. Oil has a deteriorating effect on concrete or brick
foundations. In order to protect them against the injurious
action of any lubricating oil that may accumulate on top, it
is well to provide a sheet-metal oil pan in which to place the
engine bed, or to have a 3-inch plank covered with sheet
metal to form the top of the foundation for engines of small
or medium size.

The depth of the foundation required depends on the
nature of the soil, and the pit in which the foundation is to
be built should be dug down to solid earth. The distance it
is necessary to dig in order to reach solid earth determines
the length of the foundation bolts. They should extend to

I within 6 to 13 inches of the bottom of the pit. The anchor
plates, which are attached to the lower ends of the bolts,
should be of ample size, so as to prevent any yielding of the
fotudation material when the bolts are tightened.

15. Preventing Vibration, — To prevent the vibrations
caused by the explosions in the engine cylinder from being
communicated to the building, the engine foundation should
be kept free from contact with the foundation walls of
the building. This is of special importance in office buildings,
stores, etc In cases where such vibrations are very objec-
tionable, it is advisable to take the precaution of placing the
foundation on a cushion formed by a 6-inch layer of mineral
wool, tan bark, or some other insulating materiaL This
should be placed not only beneath, but also all around the
sides of the underground portion of the foundation. Cush-
ioniag the foundation in this manner not only prevents the
_ iKUtHais&ioa of .vibratUin, but also prevents the noise cauied

8 MANAGEMENT OF § 23

by the running of the engine from being communicated to
the rest of the building. A large and heavy foundation also
tends to prevent the transmission of vibration, and when the
engine is securely bolted to such a foundation most of the
vibration of the engine will be absorbed by the foundation.

16. Tlmibep Foundations. — In localities where brick,
concrete, or stone foundations are not to be had, timbers may
be used. They should be of such length as to project sev-
eral feet on each side of the engine bed. If several timbers
are required to make up the desired height or width of the
foundation, they should be bolted together in a substantial
manner. The bolts that hold the engine to the timbers
should extend through the entire depth of the timbers and
be provided with large square heads fitted in countersinks of
corresponding size to keep the bolts from ttuning when the
nuts are tightened.

1 7. Support of Engrlnes on Floors. — Engines of small
or medium size are frequently set on upper floors, where a
brick or concrete foundation is out of the question. In such
cases, the engine is usually provided with a heavy cast-iron
base of sufficient height to allow the flywheels to clear the
floor; the heavy base absorbs a considerable portion of the
vibration, and in a measure takes the place of a foundation.
When located on an upper floor, the engine should be set in a
corner near the walls, to avoid springing the joists. In every
such case, the floor boards should be removed and a thor-
ough inspection of the condition of the joists made, so as to
be sure that they are of ample strength to sustain the weight of
the engine and absorb the shocks caused by the explosions.
Preferably, the engine should be placed so that the length
of the bed extends across the joists. In order to take in as
many joists as possible, 3-inch planks or heavier timbers
projecting several feet on each side of the bed should be
placed under it, and held to the joists by bolts extending
through and secured by anchor plates underneath. The
engine should be fastened to the plank by bolts in the same
manner as in the case of the timber foundations.

§ 23 STATIONARY GAvS ENGINES 9

1 8. Placing Sng^ine Bed on Foundation. — After the
engine bed has been brought alongside the foundation,
blocks are placed on top of the masonry high enough to clear
the tops of the foundation bolts. The bed is then moved and
set upon the blocks and gradually let down by inserting planks
and removing the thicker blocks. Generally the bottom of
the bed is planed smooth, so that, if the top of the founda-
tion is level and smooth, the bed will rest firmly on the
foundation. Any unevenness in the surfaces of the founda-
tion or of the base of the bed must be taken up by wooden
or iron wedges, which are inserted and adjusted until a spirit
level applied to the engine indicates that it stands perfectly
level. After the engine is leveled up, the nuts of the foun-
dation bolts should be tightened gradually and evenly with-
out straining the engine bed. If tightened carelessly, the
bearings of the engine in the bed may easily be drawn out
of line and cause serious trouble with hot boxes as soon as
the engine is started.

19. Grouting:. — After the bolts are tightened mod-
erately, the space between the bedplate and the foundation is
filled with grouting. The grouting may be made of iron
borings mixed with cement, sal ammoniac, sulphur, and
water in about the following proportions: two parts of sal
ammoniac, one part of sulphur, five parts of cement, and
forty parts of iron borings mixed with enough water to. make
a heavy paste. This mixture rusts firmly into place. A
joint made of a rusting mixture is generally called a rust
Joint. Sometimes, melted sulphur alone is used, but one of
the best gfroutings and the most easily* applied is pure Port-
land cement mixed with water. The rust joint must be
well tamped into place, while the sulphur and cement will
flow in, suitable dams being constructed to hold it in its
proper place. Bolt holes should also be filled with liquid
grouting. Some builders, who use hollow bedplates of box
form, fill the entire bedplate with concrete, to give it solidity
and to reduce the tendency to excessive vibration from
the knocking caused by loose bearings.

1»K— 20

... - 4.:, .•

10 MANAGEMENT OP g 33

PIPING ST8TBU

S0< Arrangement and Sizes of Piping, — It is custom-
ary for the engine manufacturer to supply a general piping
plan, giving a diagram of the various pipes and their sizes,
for the fuel-supply, the water-inlet and overflow, and the

exhaust pipes. The general scheme of these connections for
the gas and exhaust piping, subject to changes according to
local circumstances, is shown in Fig. 1. The gas enters
through the pipe a, and flows through the valve ^ to the gas

§23

STATIONARY GAS ENGINES

bag c. From c^ it passes through the pipe d to the engine
cylinder e. The exhaust gases pass from the cylinder through
the pipe /to the muffler^, and thence out of the pipe h to
the atmosphere. The gas bag is furnished with the engine,
and serves as a reservoir, which is necessary because the
charges are taken into the engine suddenly and at intervals.
During the suction stroke the gas bag will slightly collapse,
and if the pressure should accidentally fall below the normal,
the collapsing of the bag may partly close the gas pipe enter-
ing it. To guard against this, the pipes should extend well
into the bag, that is, from 6 to 12 inches, according to the size.
To prevent absolutely such interference with the supply, the
pipe may run through the entire length of the bag, the gas
entering through a series of holes drilled into the pipe.
About twenty holes, varying in size from J to 1 inch in
diameter, according to the size of the engine and supply
pipe, will be sufficient

To obtain the full power that the engine is capable of
developing when using illuminating gas, the size of the gas-
supply pipe must be ample to permit the gas to flow without
reduction of pressure, and will depend on the distance
between the engine and the street main. Table I gives a safe
estimate for the sizes of pipe to be used at different distances
from the engine for light pressures of from 1^ to 2 ounces.

TABIiE I

SIZES OF GAS PIPING FOR GAS ENGINE

Horsepower of
Engine

Diameter of Pipe, in

Inches

Within 15 Feet
of Engine

Further Dis-
tance of 90 Feet

Further Connec-
tion to Main

3 to 5

'/»

6 to lo

i>4

II to i8

*>4

19 to 28

Ij<

2>^

29 to 45

I>^

sV'

46 to 65

2>4

s'A

66 to 100

MANAGEMENT OF

§23

31. Pressure Begrulator. — In cases where the fluctua-
tions in the gas pressure must be considered, and where the
surrounding gas lights would flicker owing to the intermit-
tent drawing of gas from the main during the working
of the engine, a pressure regulator should be installed.
One form of regulator is shown in Fig. 2. It consists of a

balanced valve a, the stem of which is connected to a dia-
phragm ^, and a helical springs, the tension of the latter
being adjustable. The gas enters at d and leaves at f, the
diaphragm d being therefore subjected to the pressure on the
outlet side of the valve. If this pressure increases, the dia-
phragm is forced downwards, and the valve is closed to a
greater or less extent, tlius throttling the gas supply and
lowering the pressure on the outlet side. By adjusting tlte
spring c, any dfsired pressure may be constantly maintained
at e regardless of variations in the pressure on the inlet side.

The regulator must be placed in the supply pipe, so that
tlic gas will pjiBS th roiigh the valve before it reaches the rub-
ber gas bag c. Fig. 1.

A valve sliown at ^ should be placed in the supply pipe, so
as to shut oti the gas before it reaches the bag c, and should

§23

STATIONARY GAS ENGINES

be within easy reach, to be opened or closed when starting
or stopping the engine. As oil has a damaging effect on
rubber, the bag should be inclosed in a suitable box or
cover, in order to protect it from lubricating oil that might
be thrown upon it by the revolving parts of the engine.

33. Gas Meter. — To permit a strict account of the gas
consumption of the engine to be kept, a meter registering
the amount of gas used by the engine should be installed.
The meter should be placed as near as possible to the engine.
The following capacities of meters may be considered ample
for engines of various sizes working under normal condi-
tions, the meters being rated according to the number of
lights they will supply.

TABIiE II

SIZES OF GAS M£TKI18

Horsepower

Size of Meter, in

Rated Number

of Lights

Horsepower

Size of Meter, in

Rated Number

of Lights

26 to 35

3 to 5

36 to 45

100

6 to lo

46 to 55

200

II to i8

! 56 to 70

250

19 to 25

71 to 85

300

/53« Piping for Natural Gas. — The pipe connections
for natural gas are essentially the same as for illuminating-
gas. As a rule, natural gas is supplied at a higher pressure,
which must be reduced by a suitable regulator to about 2 to
4 otmces before it reaches the reservoir near the engine.
Owing to its greater heating value, a smaller amount of natu-
ral than of illuminating gas is required for developing the
same power, the proportion being about 75 or 80 per cent.
The size of the supply pipe near the engine may therefore be
proportionately smaller for natural gas than the sizes given
in Table I for illuminating gas.

24. Bxhanst Plplni?. — The object of the exhaust pipe
is to carry the waste gases or products of combustion into

MANAGEMENT OF

§23

the open air. To do this effectively and with the least resist-
ance or back pressure, the pipe should be of ample size and
should run as straight as possible, avoiding any sharp bends.
As the gases leave the cylinder at considerable pressure, the
exhaust is noisy unless provision is made for muffing the
sound. This is usually accomplished by inserting a cast-iron
muffler, as shown at gy Fig. 1, in the exhaust . pipe near
the engine. A flange union should be provided between the
exhaust pipe and the engine, and between the exhaust pipe
and the muffler, to facilitate the disconnecting of the pipe in
case the exhaust valve or the cylinder head needs repairing.
In placing the muffler and connecting it to the exhaust outlet
of the engine, care should be taken to give the pipe a certain
amount of flexibility, as a rigid arrangement would strain the
exhaust-valve casing, owing to the expansion of the pipe
when it becomes hot. This would result in rendering any
packing between the cylinder and exhaust-valve casing

leaky, an annoyance
that can easily be
avoided by a judicious
arrangement of the
muffler and pipe con-
nections. The most
efficient way to avoid
this difficulty is to use
an expansion joint.

one form of which is
shown in Fig. 3. The
end a of the pipe leading from the engine is free to move longi-
t udinally in the fitting A, which is screwed tightly on the pipe c
loading to the muffler. The nut </, when screwed down, com-
presses the |\icking rand prevents leakage between the pipe^
and the tittin>r b. The expansion joint is thus a simple form
i^t stuffln^K^x. the piicking beinir of asbestos wick thoroughly
hibnoatovl with c^^at^hite. Extension and contraction due to
v^aT\>:x\< v^f temporatr.re oaiise the p:pe a to move in and out
v>t the t^ttir.c > \vi:hov.t strainir.g the pipe connections. The
pijH" tn>m the n:;:f*'»or to the open air should never be smaller

FlG.S

§ 23 STATIONARY GAS ENGINES 15

than the outlet on the engine. If a long pipe with several
bends is unavoidable, the size of the pipe should be corre-
spondingly enlarged.

25. To avoid causing annoyance, from the exhaust gas,
to people in neighboring buildings, the exhaust pipe should
be carried above the roof of the building. If this is done by
way of a convenient flue or chimney, the pipe should
be carried up through the entire length of the flue. If
the pipe terminates inside of the flue, there is danger of
unbumed gases accumulating in the flue and doing serious
damage when fired by the first hot exhaust issuing from the
pipe. As the exhaust gases cool during their passage
through the pipe, a certain amount of water collects in the
pipe due to the condensation of the water vapor in the
exhaust gases. To permit the exhaust connections to be
drained, all vertical exhaust pipes should be fitted with a T
at the bottom, one opening of the T being provided with a
plug or drain cock.

In densely populated or crowded residence districts, where
even the muffled sound of the exhaust might become objec-
tionable, the noise can be entirely eliminated by injecting a
very small stream of water into the exhaust pipe. A portion
of the overflow from the water-jacket may be used for this
purpose. The connection should be made about 4 to 6 inches
below the exhaust outlet on the engine, to guard against
any water coming in contact with the exhaust valve and
poppet. A J-inch pipe will supply enough water to deaden
effectually the noise from the exhaust of a 20-horsepower
engine. The water has the effect of cooling and decreasing
the volume of the hot exhaust gases, and the greater portion
of the water is carried away with the gases in the form of
steam. A drain connection must be provided at the lowest
point of the exhaust pipe, and this must be kept open con-
stantly, to permit any surplus water to run off to the drain
pipe or sewer.

In running the exhaust pipe through wooden floors or
partitions, metal plates should be used around the pipe,

MANAGEMENT OF

!2S

§ 23 STATIONARY GAS ENGINES 17

allowing 3 or 4 inches clearance between the pipe and the
floor to protect the woodwork from danger of fire. For the
same reason, the exhaust pipe, if placed on a wooden floor,
should rest on bricks or similar material. If the exhaust
outlet ends in a vertical pipe, it is advisable to place an
elbow at the top end, to prevent water or solid obstacles
from getting into the pipe.

36, Piping for Gasoline. — Considerations of safety,
embodied in the regulations laid down by the National
Board of Fire Underwriters, require that the supply tank of
a gasoline engine be placed about 30 feet from the building,
and below the level of the engine-room floor, making it
impossible for the gasoline to flow to the engine by gravity.
Such an arrangement is shown in Fig. 4, with the engine
at rt, the gasoline tank at ^, and the pump at c. The tank b
should be so placed that the bottom of the tank will not be
more tlian 5 feet below the level of the pump i\ as, owing to
the nature of gasoline, it cannot well be raised through a
greater height even with a well-constructed pump. The sup-
ply pipe d is attached at the bottom of the tank, and should
have a constant rise toward the engine. The tank is placed
preferably in a brick-lined vault, large enough to allow access
to the valve e or other valves in pipes near the tank. The
overflow pipe/", through which the gasoline returns from the
cup ^ to the tank, enters the tank above the supply pipe d,
A drain cock must be placed at the lowest point of the tank,
to allow any water that may accumulate there to be drained
off. Moreover, the gasoline may contain a little water, which,
being heavier, will settle to the bottom of the tank, and
in time will increase in quantity to such an extent as to be
drawn into the engine and cause it to stop.

27. Stop-cocks should be provided in both supply and
overflow pipes near the tank. They may be closed, so as
to allow the pipes and connections to be examined without
having to empty the reservoir. A stop-cock in the supply
pipe, to be closed when the engine ib shut down overnight,
has the additional advantage of keeping the pijxj filled

18 MANAGEMENT OF §23

with fuel and obviating the necessity of having to pump it
up by hand before starting the engine in the morning. It is
very important to have all joints in the gasoline pipes per-
fectly tight. Galvanized pipe and fittings should be used and
all screwed joints soldered. Before the pipes are put in
place, they should be thoroughly cleansed of any impurities
by washing with kerosene. All pipes and fittings should be
carefully examined to make sure that they show no defects,
such as imperfect seams or blowholes, that would admit
air into the pipe and prevent the pump from lifting the
gasoline.

A filter, shown at A, Fig. 4, is usually furnished with
the engine; it should be placed in the supply pipe before
the point where this pipe enters the pump. Neglect in
supplying a filter may result in impurities being washed out
of the pipe, settling under the pump valves, and interfering

Pio. 5

with the action of the pump. In case no filter is supplied
by the maker of the engine, it is well to provide one. In
Fig. 5 is shown a good form of filter, which is made of fine-
wire gauze a inserted in a short nipple b and held in place by a
standard brass union r, the gasoline passing through in the
direction of the arrow. The gauze is held in place by a brass
ring dy and the joint is made tight by a leather washer e.
In running the gasoline pipe to the engine, care should be
taken to keep it away from the exhaust pipe, as the heat
from this pipe would interfere with the flow of gasoline by
producing a quantity of gas in the pipe that would prevent
the liquid from being pumped up into the engine. Gasoline
pipes that are placed underground should not be covered with
earth until a test has proved that they are perfectly tight

§ 23 STATIONARY GAS ENGINES 19

It is well to make sure of this by starting up the engine,
keeping it running for a day or two with the pipes exposed,
and watching for leaks. To facilitate taking down any pipe
connections near the engine or disconnecting the tank, use
brass unions in the gasoline pipes near the pump and the tank.

COOT.IXG SYSTEM

28. Temperature of Cooling: Water. — In a well-con-
structed gas engine having ample cooling water space around
the cylinder and valve-casing, the water supply should be so
regulated as to maintain a temperature of about 160° to
180® F. This temperature will prevent excessive heating, which
wotdd interfere with the proper lubrication of the piston and
cylinder and with the easy operation of the valves and igniter,
as well as destroy the packings between the cylinder and the
valve casings, where such packings are employed.

Keeping the temperature of the cooling water much below
160° F. would have an injurious effect on the condition of
the piston and cylinder, and prevent getting the best results
from the engine, even with a proper combustion of the mix-
ture in the cylinder. If the water when it leaves the cylinder
is practically cold, the cylinder will be cooled to such an
extent as to cause condensation of the exhaust gases, result-
ing in corrosion, imdue wear of the piston, and sticking of
the piston rings, and a large amount of heat that should be
utilized in doing work will be carried away by the water.

29. Tank System of Cooling. — For engines of small or
medimn size, cooling by means of a water tank, as shown in
Fig. 6, is most efficient and least expensive. When employ-
ing a tank of proper size, the question of keeping the water
at the proper temperature is easily solved. The amount of
water that must be added in this system of cooling is limited
to the small quantity that is lost by evaporation. The essen-
tial points to be observed in making connections between
the engine and the tank are as follows: The tank must
be of such shape that the opening for the pipe a at the top

20 MANAGEMENT OP §3

is at least 3 feet above the top of the engfine cylinder i. Th
pipe must be of ample size, so as to afford little obstmctioi
to the circulation of the water. The water should be talei
from a convenient point immediately above the bottom o
the tank, and should enter the cylinder jacket at the bottoi
and leave at the top. The level of the water in the tanl

•liiMiki always \ c several iiK'hcs abuve the entrance of t
lv^iiot- pijv It ncir \\k- top of the tank. A drain cuck c shou
'.■ j'I.iolhI at thi' 1. ivi-sl point <'t the pipe, to allow the water
V ilr.uvn ntT !i ci'!i! weather, and thus prevent freezii
n.l 11 >T' SOI I ;',—.: ^i;-sting; of t^c water-jacket The vertii
'■jv ;' i:;-v.\ iVo i.;ekot lo c'-.o t.ir.k shoitUI Ix; extended frc

§ 23 STATIONARY GAS ENGINES 21

6 to 12 inches above the water level in the tank, as shown, to
allow for the escape of air and to facilitate the circulation.
Where the engine is not placed on a rigid foundation, short
pieces of rubber hose ^, f should be inserted in the hori-
zontal pipes at top and bottom, so as to prevent the com-
munication of any vibration from the engine to the tank.
The valves g and h permit the tank to be shut off when the
cylinder jacket must be drained.

30. The capacity of the cooling- water tank for an engine
running under an approximately full load may safely be put
at 50 gallons per horsepower. For large engines, above 20
horsepower, the tank system of cooling may be successfully
employed, if supplemented by a circulating-water pump
driven from the engine or any part of the line shaft. The
pump must be so set and connected as to take water from the
bottom of the tank or cistern, force it through the jacket,
and return it to the tank. If the cistern or tank capacity is
limited, which is likely to be the case in large installations,
the use of suitably constructed air-cooling arrangements is
necessary. These arrangements generally consist of a series
ot slanting surfaces, one below the other; the water, after
passing through the engine, is delivered by the pump to the
top of the cooler, and descends by gravity, flowing over the
surfaces and being cooled by contact with the air, before it
returns to the tank or cistern. The capacity of the water-
circulating pump should be about 15 gallons per horsepower
per hour.

31. Coollngr by Steady Water Supply. — Where a
steady supply of cold water from water mains or any other
source is convenient and inexpensive, the supply pipe can be
of smaller size than when using the tank or circulating sys-
tem of cooling. A J-inch pipe at moderate pressure will
supply enough water for a 5-horsepower engine and a 1-inch
pipe is sufficient for a 40-horsepower engine, larger engines
requiring proportionately larger supply pipes. The water
supply pipe, shown at rt:,* Fig. 7, should enter the engine at
the ix>int that is likely to heat most rapidly, generally at the

MANAGEMENT OF

exhaust-valve casing or cylinder head, and the outlet pipei
should emerge from the top of the cylinder jacket. The
outlet pipe should discharge into a funnel c, in order that it
may readily be seen whether the water is flowing or not,
and that the temperature of the water may be better observed.
The overilow pipe </ should be one or two sizes larger than

the supply pipe, in order that all the water that is
brought to the engine under pressure may flow off by
gni\ity. Pro\nsion should always be made by a suitably
placed dniiii conueclion t* for emptying the cylinder jacket
in C(.4d n'oathor, to guard against craddngof the jacket vails
thrvmgh the fn.>eEing of the water.

S^. IK'ptisits lu Water-J^acket. — If the cooUng water
Cv>ntnin!i lime or alkali, the heating of the water in the jacket
will i.\»uj<" thcso solid substances to be deposited in the cooling
sjviocs. This will six^n choke any narrow ports and preveiit
pT\''jXT ciivul.itiv^n. Tvsulting in overheating, rapid wearing of
tV.o valvvs. .mii Kiss of power and eflBciency. A simple
:x-:'.-vv'.y vv.^xsts ot t'-.e appMcaiion. at regular intervals, of a
\*','v.;e Av-,;:-".-r. o; hy^ir^x'hlorv, or manatee, acid, made as
;V".,-ns- '."*'■.■.:!." OT^e 'Air; o:" — ^r'^rc scidwiA rineteeu parts
,-; w.;:,r, .1".,', A'tcv v:--.-~"-:ir :'-e -jcket cvinpleteh-, po=r:=
<.— ,-.\c^ of :V #,•"":■.!•. :o r" :V.e enriv cvwEi;? space. AToir
*.V ■.•".\;"Tv '.o-vr'-vr-. ir, ;'^f ■.u-ke: ^.r- sot-^core z'rsr. ^ t' U

§ 23 STATIONARY GAS ENGINES 23

hours, after which wash the cooling space thoroughly by
loinning clear water through it. If the solution is permitted
to remain in the jacket longer than the period stated, there
is danger that the metal may be damaged by the action of
the acid. The acid will soften and dissolve the lime or
alkali, and the clean water will remove it from the jacket.
It is generally sufficient to apply this method of removing
the deposits once every two weeks. If neglected too long, the
acid will not dissolve the deposit.

ASSEMBLING £K6IN£ AND ADJUSTMENT OF PABTS

33* Shaft and Flywheels. — Before assembling any parts
of the engine, they must be thoroughly cleaned of any dirt,
dust, antirust, or packing material, and lubricated where
necessary. After the engine bed has been securely placed
upon the engine fotmdation, the working of the crank-shaft
in its bearings should be examined to see that it turns
easily. Only very small engines are usually shipped with
the shaft in place and the flywheels keyed to the shaft. If
the wheels are shipped separately, they should not be put on
the shaft until it has been ascertained that the latter does
not bind in the journal-boxes. When lifted by hand,
the crank should drop by its own weight from a horizontal
position. The timing of the valves and igniter depends on
the relative position of the teeth in the gears on the crank-
shaft and cam-shaft. As a rule, the gears are marked by
ciphers or similar symbols, and must mesh so that the mark
on the tooth of one gear comes opposite to a like mark on
the space between two teeth of the other gear. This should
be investigated before any attempt is made to put the wheels
on the shaft

34. See that the bore of the flywheels and the surface
of the crank-shaft are clean. Then oil both parts with lubri-
cating oil. Usually each wheel and each key is numbered,
and care should be taken to place them so as to go on the
side marked with corresponding numbers on the end of the

24: MANAGEMENT OF §23

shaft. If the weight of the wheels makes lifting by hand
impossible, place planks on the floor underneath the crank-
shaft, and roll the wheels up on these plants until the bore of
the hub stands exactly opposite the end of the shaft 'I'hen
work the wheel gradually over toward the shaft until it rests
against the end of the shaft. By a concerted eflEort of the
men handling the wheel, it will then be easy to slide the
wheel on the shaft for a distance of an inch or more. Now
place a block of wood betwefen the crank and the engine bed,
so as to prevent the crank from moving when turning the fly-
wheel to the right. Be careful, however, to place the wood so
as to avoid danger of breaking the bed. Then, while one or
two men hold and balance the wheel, turn it slowly and
gradually around on the shaft toward the right, at the same
time pressing it on the shaft until it is worked on the shaft
the full length of the hub. Remember that the wheel has
been on the shaft before, and if it is found that it sticks and
refuses to turn, look for obstacles such» as dust or chips,
and take off the wheel at once before the bore of the wheel
and the surface of the shaft are damaged by cutting.

35, After the wheel has been put on the whole distance,
turn it so that the keyway in the wheel stands exactly oppo-
site the one in the shaft, and drive the key in by means of a
sledge or a large-sized hammer. The keys should be well
lubricatet.1 before being driven. If two keys are used in one
wheel, drive them in gradually and evenly. Driving in one
key at a time, all the way, will result in throwing the fij-wheel
iHU and prevent it tnnn running true. Care should be taken
in strikinir the ends or heads c»f the kevs with a hammer, as
they may break off if not siruck squarely.

I: is soir.eiimes found, after placing the wheel on the shaft,
:liat it ovx^sr.vn nm true. This may be due to careless ban-
v'.V.r.c v.". shi inking or imlvXiding. The damage can be repaired
..•\: t'x^ \v*u\ '. :r.,u!e :v> rv.r. true by careful hammering of
s*\^<c> ' oj.r t'^ie r.v.b. Tv^ ascertain which part of the
n' "v .\:s straic-'or/.r.c t':m it slowly by hand, holding

lo^e to the rim, thus marking the

■^ . \

§ 23 STATIONARY GAS ENGINES 25

higher part of the rim. Then strike the spoke or spokes
under this part of the rim with the blunt end of a medium-
sized hammer. To avoid injuring the paint, hold a piece of
sheet copper against the part of the spoke with which the
hammer comes in contact, and strike a spot about 2 or 3 inches
distant from the outside of the hub.

36. Piston and Connectinfi^-Bod. — The piston and
connecting-rod are generally shipped detached, and, even
if they are in position when the engine is received, it is
advisable to disconnect the rod, take out the piston, and
thoroughly examine both. Remove all antirust material
used in packing by washing the surfaces in kerosene and
rubbing with cotton waste. See that the outer surface of the
piston is smooth, arid that the edges have not been damaged
in handling. If necessary, smooth off any slight ridges with
emery cloth or a very smooth file. The closed end of the
piston, which is exposed to the combustion, must be smooth
and must not show any imperfections in the casting, such as
blowholes or sandholes. Defects of this nature may easily
cause premature ignition of the charge.

The piston rings should move easily in their grooves, with-
out, however, any lateral play. If they stick, use kerosene
freely, until any gummy oil or material has been washed
away. If the piston pin that holds the piston and connecting-
rod together is lubricated through a hole in the wall of the
piston, see that this hole is clean and affords no obstruction
to the flow of oil to the pin.

37. Clean both bearings of the connecting-rod, and after
cleaning aud giving a liberal coat of oil to the piston pin,
insert it in the piston, with the rod held in place between the
bosses inside of the piston. The inner walls of the latter
should be free from any trace of molding sand, turnings, or
filings that might find their way into the cylinder and cut
the working surfaces. It is good practice to give the rough
inner piston surface a coat of black fireproof asphaltum paint
before the piston is placed in the cylinder. This should prop-
erly be done by the maker of the engine, but, if neglected, it

26 MANAGEMENT OF § 23

will benefit the purchaser to have it attended to before any
attempt is made to start the engine. Clean the interior of
the cylinder and examine the condition of the working
surface to make sure that it is in perfect condition and
shows no longitudinal scratches or ridges caused by the cut-
ting of the piston.

38. After the piston pin has been inserted, tighten the set-
screws and locknuts used for holding the pin in place. Apply
a liberal quantity of cylinder oil to the outer surface of the
piston, which is now ready to be placed in the cylinder. The
end of the cylinder nearest the crank-shaft is usually tapered,
so as to make it from ^ to {^ inch larger in diameter than
the piston, to facilitate the insertion of the latter into
the cylinder. The piston rings, being naturally expanded,
must be compressed so as to enable them to enter the cylin-
der. In small engines this can be done by hand, while in
larger pistons, it will be found more convenient to use cord
or thin flexible wire with which to draw the rings together.

39. After the piston has completely entered the cylinder,
move it backwards and forwards several times to ascertain
whether or not there is any obstruction to prevent it from work-
ing freely. The cap of the crankpin bearing of the connect-
ing-rod having been removed, the crank is now turned so as to
bring the crankpin opposite its bearing, and the rod and
piston are moved out until the bearing rests against the pin.
Then put on the connecting-rod cap and tighten the bolts
until the bearing is properly adjusted. Always use a liberal
amount of lubricating oil on both pi^ and brasses before
putting them together.

40. Valve-Ck^ar Shaft, Valves, and Governing

Moohanisni. — In most cases either the crank-shaft or the

scooTularv or cam-shaft is shipped detached from the engine,
:r^! Tv.iist Iv put in place by the erector. As the time of open-
i:vc aTul closinvr the inlet and exhaust valves, as well as the
PvvItu of ivTvition, is detcTmined by the cam-shaft, it is obnous
that there is a oenain relati\-e position of the gears that drive

STATIONARY GAS ENGINES

the secondary shaft. These gears may be spiral, spur, or
bevel gears, but in any case it is necessary that the teeth of
the gears mesh so as totime the valves and igniter properly.
This time having been determined at the factory when the
engine is assembled and tested, the maker generally marks
the gears by letters, ciphers, or similar marks, one on the
tooth of the driving gear, and a corresponding mark on the
space betft'een the teeth of the driven gear.

41. When placing the shafts in their bearings, be sure
to look for these marks, and put the gears together so that
they mesh as intended. The maker of the engine is of course
supposed to know the exact timing of the valves and igniter
that will give the best results obtainable with his particular
engine, considering its design, speed, etc., and no attempt
should be made by the purchaser or attendant to improve
,the tengine in this respect. Generally speaking, however,
the exhaust valve should close at a point when the crank-
shaft has passed the inner dead center, after the end of
the exhaust stroke, by from 6° to 10°. The length of the
cam or other similar device used for operating the exhaust
valve will then determine the point of opening, which, in an
engine of moderate speed, will be about 40° to 46° before
the crank reaches the outer dead center on the working, or
expansion, stroke.

The inlet valve, if operated by a cam or a lever, generally
opens a little before the beginning of the suction stroke, pos-
sibly 5" to 10', so that for a very short period of time both
inlet and exhaust valves are open, say during 10" to 20° of
the crank movement. The inlet valve will generally be found
to close, when the crank has passed the outer dead center,
at the end of the suction stroke — to an extent of from 15° to
30°, dependingon the fuel and other conditions. If operated
by the partial vacuum inside of the cylinder, created by the
outward movement of the piston during the suction stroke,
the inlet valve of course opens and closes automatically,
and the timing is regulated by the tension of the inlet-
Wlhie spring.

28 MANAGEMENT OF §23

42. The timing of the fuel-admission valve, where the
valve is mechanically operated by cam and lever or some
similar device, depends on the kind and quality of fuel used,
and also on the pressure at which it is supplied. With
illuminating gas at the average pressure, the valve should
open when the crank has passed the inner dead center about
15° and close about 30*^ after the crank has passed the
outer dead center. The same timing of the air-inlet and
fuel valves will be found to give the best results when using
gasoline as when using illuminating gas, if the gasoline is
supplied through a nozzle controlled by a small popppt valve
actuated by cam and lever.

43. As natural gas is much superior to illuminating gas in
heating value, a differently proportioned mixture is required,
which is usually regulated by throttling the gas-cock on the
engine so as to suit the quality of the fuel available. The
timing of the fuel valve is the same, however, as when using
illuminating gas. But the poorer qualities of gas, such as
producer gas or fuel of correspondingly lower heating value,
require a longer period of time during which the gas valve
must be open. Generally, it will be found that, in order to
get good results, the valve must begin to open at about 15°
before the crank passes the inner dead center, previous to
the suction stroke, and remain open until the crank has
passed the outer dead center about 40°. As stated before,
these angles are only approximate, and they vary slightly
according to the design of the engine, the area of the valves,
and the speed at which the engine is operated.

44. After the cam-gear shaft has been properly placed
and secured in its bearings, turn the engine over slowly and
see that the shaft and the parts actuated by it move freely.
Attach any levers, links, o^ rods that may not be in place
when the engine is taken from the boxes, lubricating all
pins and pivots carefully before putting them together. See
that any valves closed by springs come to their seats quickly
if pushed in by hand and released. Apply a liberal amount
of kerosene to all valve stems, so as to remove any gummy

§23 STATIONARY GAS ENGINES 21)

or similar matter with which they may have become coated.
Give special attention to the governor, on whose free move-
ment depends the regularity of speed of the engine. All
links and pivots connected with the governing mechanism
should be washed with kerosene and then lubricated with a
light oil of good quality.

45. Attacliment of Xiubrlcators. — Before attaching
the lubricators furnished for oiling the cylinder, bearings, and
principal moving parts of the engine, the oil cups should be
carefully examined for any dust or other impurities that they
may contain. See that they are perfectly cleaned before
they are put in place and filled with oil.

The tapped holes for receiving the individual oil cups and
the holes through which the oil is supplied ta the parts to be
lubricated should also be examined with great care, and any
waste or similar obstructions that would tend to interfere
with the supply of oil should be removed.

IGNITION SYSTEM

46. Battery and Spark Coll. — The matter of installing
the battery, spark coil, switch, and wire connection deserves
the most careful attention. The battery cells should be
charged and the wire connections between the battery and
the engine made according to the instructions sent with
the particular make of battery used in connection with the
engine to be installed. As a matter of fact, the larger part of
the trouble with internal-combustion engines is due to the
igniter and its connections. Some of these difficulties will
occur if every possible care is taken, but most complaints
can be traced to neglect or carelessness in installation or
ignorance in operation.

As the make-and-break contact system is used almost
exclusively on stationary engfines, only this method will
be considered at present. A good quality of insulated fire-
proof and weatherproof copper wire should be used to con-
nect the individual cells of the battery and the spark coil

30 MANAGEMENT OP §23

with the battery and engine. Flexible rubber-covered or
stranded wire is also permissible. In fastening the wires to
the ceiling or walls, do not use metal clamps, which are liable
to injure the insulating material, but use wooden or fiber
cleats cut out to suit the thickness of the wire. Avoid splic-
ing whenever possible; but, if it is necessary to employ
splices, make them carefully and solder them securely. The
wire should be of such length as to reach from 6 to 9 inches
beyond the binding post to which it is to be connected. To
avoid any pulling on the wire or post, the extra length should
be coiled on a ^ inch round rod, slipped off, and left as a
spiral between the straight wire and the binding post

47. Electrical Connections. — The spark coil must be
set in a dry place and must be well protected from moisture,
which causes short-circuiting and prevents ignition. All
terminals of the wire connections must be clean and bright,
to insure good contact The connections between the cells
should preferably consist of fle^tible insulated wire, with flat
Clipper washers soldered to the ends, the hole in the washer
fitting easily on the binding post Connections of this kind
may be purchased from almost any electrical supply dealer,
if they are not already furnished with the engine.

As a rule, an ordinary two-pole, or two-point, switch,
with loYor-handle contact will answer all purposes. These
switches ha\-e the advantage of being easily examined and
kept in orvicn Knife switches are equally well adapted for
\i5?c in engine rvx^ms^ while if the switch is necessarily
ox*jXvv\l tv^ out-ofndoor atmosphere an encloGed switch, such
as is u:x\l tor iucAnviosoent lights, is more suitable.

4S, lirnltlon PUur. — The ignition plug containing the
e\v:rvxU^s '.v.r.s: bo oxani:t^ed as to deanKness, freedom from
vvrTv>s:on» cs:xv:A!'y v^f tbe cor.ract points* and easy move-
•*^ov.: v>f tVo n*.o\Vib!o e!tvtTvv5e. befo^re being attached to
•/*v^ vV.vbusti.^" o^.v^^iSl^t AV>.r.e :be engine is at work, the
\v ;;, N^ -^C i\iv\^v. :.^ t'^e ht,-.: ?f the combustion, will
o\a;'*/ s' c^'*'^" •"> "v :'''*,i-*. :'"'c <*,:rrr^niinc waZTs. It is evi-

STATIONARY GAS ENGINES

in case of necessity, after the engine has been running for
some time, it must, when cold, enter its aperture easily and
witliout having to be forced. The packing surface of the
ping, making it tight against tlie pressure in tlie cylinder, is
a ground joint, either flat or tapering, or a flat ring-shaped
surface packed w-ith sheet asbestos. In either case, thepack-
ingsurfaces must be thoroughly cleaned before the plug is put
in place anti tightened up,

49. Point of IgDltlon. — The point of ignition varies in
accordance with the quality of the fuel and the speed of the
engine. At medium speed, whea using iUuminaiing gas or
gasoline, the ignition should occur just before the end of the
compression stroke, with the crank standing at about 15" to
20" below the inner dead center. Natural gas, as well as
producer gas, the combustion of which is somewhat more
sluggish, requires a diflferent timing of the igniter, and the
spark should occur when the crank stands about Z'i" to 35°
below the inner dead center.

50. Testing: the Eleetrlcal Connections. — The testing

of ibeelectrical connectionsmay be said tocomplete the instal-
lation of the engine and put it in condition for starting. To
determine whether the wires transmit the current in the
proper manner, connect the battery, spark coil, switch, and
engine as directed. Then disconnect the terminal attached
to the fixed electrode, turn the engine to such a position that
the two electrodes will be in contact, see that the switch is
turned on, and wipe the end of the wire against the surface
of the nut that holds the fixed electrode in place. If every-
thing is in good order, a bright spark will then be produced.
On the other hand, after turning the engine so that the con-
tact between the two electrodes is broken, no spark should
appear when the fixed electrode is touched and wiped in this
manner; in wiping any other bright part of the engine, how-
ever, a spark of similar intensity to that just referred to
1 be produced.

;32 MANAGEMENT OF §23

STARTING THE ENGINE

PREPARATIONS FOR STARTING

61. Adjustment of liUbricators. — After the engine
has been assembled and connected, the oil cup should be
filled and tested to ascertain that the feeds work properly.
The adjustment of the cups should at first be such as to sup-
ply a rather liberal number of drops; later, the quantity of
oil may be cut down to the normal amoimt, after it has been
demonstrated that the bearings nm cool. In a vertical
engine using splash lubrication, fill the oil well in the base
until the ends of the connecting-rod bolts dip about \ inch
into the oil when the crank stands at its lowest point Make
sure that all links, levers, and pivots have been lubricated,
that the valves and igniter move freely, and that the water
supply, if taken from the mains, is circulating properly.

To make certain that the crankpin and the piston pin are
properly lubricated before starting, apply a small quantity
of oil to each by hand, without relying on the lubricator or
mechanical oiler provided for the purpose of oiling these
parts while the engine is running. Sometimes these devices
may fail to perform their functions as promptly as is neces-
sary, and a hot bearing may result, causing serious trouble
that could have been easily avoided by taking this simple
precaution.

52. The oil wells of the ring-oiling bearings should be
filled to the proper height, and it should be ascertained that
the oil ring or chain moves freely, so that it will distribute
the oil over the journal surface when the shaft revolves.
Wiper oilers must be adjusted so that the moving element
of the de\ice touches the stationary part of the oil cup only
lig^htly enough to wipe off any drops of oil suspended fr<jni
the metal tip or wick of the feeding dexice. If the wiper
scrapes too hard against the tip of the cup, it will waste oil
and throw it over the encrine.

§ 23 STATIONARY GAS ENGINES 33

Worm or spiral gears, which are often employed to trans-
mit motion from the crank to the cam-shaft, are usually run
in an oil bath. The casing containing these gears must
therefore be filled with oil before starting.

53. Examination of Piston. — Examine the way in
which the piston works in the cylinder. A proper fit of the
piston is of the utmost importance, in order to obtain good
service from the engine. It must move freely, but at the
same time must prevent any loss of pressure during
the compression and expansion strokes. When turning the
engine by hand, there must be no hissing sound during
the compression; this would surely indicate a defective piston
or improperly fitted piston rings. A perfectly fitted piston,
tried in this way, will rebound before the end of the com-
pression stroke is reached.

54. Examination of Valves and Igniter, — If the

engine can be turned over easily through the compression
stroke, it will be difficult or impossible to start it. The
loss of pressure, however, which prevents proper com-
pression, is not likely to be due to an imperfect piston,
especially in a new engine, but rather to a valve that leaks
or to leakage about the movable electrode. It is well, there-
fore, to ascertain the cause of such a leak, by thoroughly
examining the inlet and exhaust valves and the igniter.
Possibly one of the valve stems or the electrode may stick in
the guide, or there may be an obstruction on one of the
valve seats. Where packings are used, one of them may
have been damaged or partly blown out.

An application of kerosene to the valve stem will wash
away any thick oil, grease, or similar substance that may
cause the valve to stick. If impurities have been deposited
on the valve seat, they can usually be removed by lifting the
valve by hand and cleaning the seat with a scraper or some
similar tool. In the case of larger valves seated in casings too
heavy to be handled conveniently, the valve may have to be
taken out before the seat can be examined and cleaned.

The renewal of a packing, especially when the packing

34 MANAGEMENT OP §23

surface is of considerable size, is a more serious matter, and
should not be undertaken until a careful examination has
shown the necessity for doing so.

56. Adjustment of Igrnition Device. — ^Where an incan-
descent metal tube is used for igniting the charge, this tube
must be brought to its proper temperature before the engine
can be started. The heating devices used in connection with
these tubes differ according to the fuel employed. In any
case, however, whether the fuel is gas or gasoline, the
burner must be so adjusted that a sufficient quantity of air
is supplied to obtain a hot blue flame. A yellow flame
indicates a lack of air. The degree to which the tube is
heated not only influences the point of ignition but also has
a material effect on the life of the tube.

Iron tubes, while less expensive, do not last so long as
tubes made from special nickel 'alloys; but, in either case,
the life of the tube is shortened by overheating. This will
readily be understood when it is remembered that overheat-
ing causes the tube to become soft, in which condition it can-
not resist for any length of time the high explosive pressure,
which has a tendency to burst the tube. Generally, the
most favorable condition in regard to the proper timing of
the ignition and the longest possible service is reached if the
tube is heated to a bright cherry red.

The preparation of electric-ignition devices previous to
starting the engine has already been explained. The engine
having been properly assembled and connected, the lubrica-
tion having been attended to, the valves moving freely and
seating tightly, and the means of igniting the charge being
in good working order, the engine may be considered ready
for starting.

56. Means of Starting:. — Small engines are often
started by hand, simply requiring the opening of the fuel
cock and the turning of the flywheel until the charge thus
admitted is ignited, giving the engine an impulse sufficient
to carry it over the following strokes of its cycle until sub-
sequent charges are admitted and ignited. In this manner,

§ 23 STATIONARY GAS ENGINES 35

the engine reaches its full speed when from ten to twenty
explosions have taken place, the number of explosions
depending on the weight of the flywheeL An engine
equipped with heavy wheels requires, naturally, more
impulses before attaining full speed than one with light
wheels.

57. Dlfflcnlties In Startlngr- — Difficulties in starting
usually met with in practice may be due to various causes.
Above all, it must not be supposed that an engine that has
nm regularly for a period of time will refuse to run without
cause, and the origin of the trouble should be located as
speedily as practicable. The most common sources of trouble
in starting are improper proportion of the constituent parts
of the mixture, failure of the igniter and its connections, or
loss of pressure during the compression and expansion
strokes. A proper proportion of air and fuel is of great impor-
tance to prompt and effective combustion. It should be
remembered that when starting by hand, with the piston
moving slowly, the fuel valve remains open for a longer
period of actual time than when the engine is running at its
normal speed. The fuel being usually supplied under a cer-
tain amount of pressure, while the air is drawn from the
atmosphere, it follows that, with the engine turning slowly,
the proportion of fuel to air is greater under these condi-
tions than under normal working conditions. This condition
is made still worse when the inlet valve is of the auto-
matic type, being opened by the partial vacuum created in
the combustion chamber by the outward movement of the
iriston.

58. Befiralation of Mixture In Starting^. — In order
that the quantities of air and fuel may be regulated so as
to admit a mixture of the proper quality, the fuel cock
should be only partly opened during starting. The cock or
throttle being usually fitted with a graduated dial, the opera-
tor will be able after a few trials to determine at which
point of opening the engine will start readily. When using
illuminating gas, this point will vary in accordance with

3(5 MANAGEMENT OP §23

fluctuations in pressure that may occur at different times of
the day.

A common mistake made by inexperienced operators is to
admit too much fuel to begin with, and if the engine natur-
ally fails to ignite, to still further open the fuel cock and
thus aggravate the trouble. This applies equally well to
gaseous and to liquid fuels. As a result of opening the fuel
supply too wide, the combustion chamber becomes flooded
with gas or vapor, and conditions are not improved until
the supply has been shut off completely and the engine
turned over several times, so that the contents of the cylin-
der are expelled through the exhaust pipe.

69. When operated with illuminating gas, it \^'ill gen-
erally be found necessary to first open the valve in the pipe
back of the gas bag, let the bag become inflated, then shut
off the valve, and start the engine on the pressure exerted
by the gas contained in the bag and pipe between it and •
the engine. As soon as the bag shows signs of becoming
empty, which will occur after a few explosions, the fuel cock
must of course be opened.

When using gasoline, the air can vaporize only a certain
quantity of fuel. Any excess will be deposited and will
accumulate in the inlet passages and in the combustion
chamber, and the longer the wheels are turned with this
excessive opening of the fuel supply, the more aggravated
will the trouble become. Frequently, if under these con-
ditions the fuel supply is shut off completely and the turn-
ing of the wheels continued, an explosion will occur as soon
as the amount of fuel carried into the cylinder is reduced to
the point when a properly constituted mixture is formed.

60. In a well-designed engine, the fuel cock is propor-
tioned so that it must be opened full, in order to obtain a
perfect mixture %vith the engine running at full speed.
Engines with air-inlet valves positively operated by means
of cams and levers are less liable to failure in starting
caused by improper proportions of the mixture. This is due
to the fact that in such engines the air-inlet valve and the

§ 23 STATIONARY GAS ENGINES 37

fuel valve are open during the same period of time, thus
regulating to a certain extent the quantities of air and fuel
forming the charge.

61. In engines operated on liquid fuel, such as gasoline,
kerosene, etc. , the fuel must be pumped by hand until a
sufficient quantity is raised from the supply tank to the
level of the fuel-admission valve to start the engine. The
fuel is generally pumped into a small cup provided with an
overflow pipe, which returns to the supply tank any excess
amount of fuel over that which fills the cup to a certain
level. This cup and overflow device may be a part of the
fuel valve or it may be separate.

When first starting the engine, it may require quite a
number of strokes of the fuel pump before the air in the
suction pipe between the tank and engine is pumped out and
the liquid delivered to the valve. If there is difficulty in
pumping the fuel, it is a sure sign of leakage of air in the
supply pipe; if the liquid does not stay in the cup after
being pumped up, it indicates tljat there is leakage at some
point between the cup and the engine. Before attempting
to run the engine, therefore, the pipes and connections
should be carefully examined, the leak located, and any
imperfect joints made tight.

63. In the modern gasoline engine, a mechanically
operated device, which determines the exact amount of fuel
sprayed into the air, atomizes the gasoline while entering
the mixing chamber at a certain velocity. It is therefore
evident that the forming of a proper mixture and the conse-
quent prompt starting are not dependent on atmospheric
conditions and quality of the fuel to the same degree as
when the old type of vaporizer was used. Nevertheless.
in extremely severe weather, in locations where the engine
room is not kept warm during the night, and especially
when the fuel used is of comparatively low specific gravity,
it may become necessary to aid the atomizing of the gaso-
line by heating the combustion chamber in some manner
before starting can be attempted.

38 MANAGEMENT OF § 23

The fuel is sometimes heated by removing the inlet- or
exhaust-valve cover and placing a quantity of cotton waste
soaked in kerosene in the combustion space and lighting the
waste, but this is a crude and dangerous proceeding and
cannot be recommended. In 'addition to the danger con-
nected with an open flame, the burning of waste may easily
result in leaving in the chamber fragments of the material,
which may be drawn into the cylinder and interfere wnth
the proper working of the piston, valves, and igniter. An
absolutely safe way of accomplishing the desired object is to
fill the empty water space in the jacket with hot water pre-
pared for this purpose. This will increase the temperature
of the walls surrounding the combustion chamber sufficiently
to aid in the vaporization of the fuel and make prompt start-
ing more certain.

63. No set rules can be laid down that will tell the opera-
tor just how to obtain a perfect mixture at all times.
This depends on the design of the engine and on the condi-
tions surrounding each individual case, which may necessitate
a different method from that which must be observed in
another engine of the same type or make. Indications of a
good mixture will manifest themselves to an observant
operator by the sound of the impulse and the appearance of the
exhaust at the end of the exhaust pipe. A smoky exhaust is
a certain sign of an excessive amount of fuel, and a mixture
of this kind also produces a weak impulse. If the exhaust is
clear and it requires the admission of several charges in suc-
cession before an explosion occurs, the indications are that
the fuel is not admitted in sufficient quantity. This condi-
tion also manifests itself by back flringr or explosions in
the air pipe and passage, caused by retarded combustion of
the charge, the mixture being still burning at the end of the
exliaust stroke and igniting the incoming charge while the
inlet valve is still open.

04. RepTulating Gas Pressure. — Engines operated
with illuminating or natural gas require the same amount of
judgment in determining the amount of fuel to be admitted

STATIONARY GAS ENGINES

vrhile startinff the engine as does a gasoline engine. If
illuminating gas is used, the pressure is regulated at the
gasworks, and any slight fluctuations are equalized by use
of a rubher bag, as already explained. When running with
natural gas or pnxiucer gas, the pressure is frequently regu-
lated by a small gasometer, as illustrated in Fig. 8, consist-

JDg of a tank a partly filled with water in which is sub-
merged a float b, closed at the top and open at the bottom.
The gas-supply pipe c from the main enters the gasometer
at the bottom and extends through the watpr into the float,
while the pipe d connecting the gasometer to the engine is
attached in a similar manner. The float b is connected to
the valve cva. the supply pipe in such a manner that, when
the float becomes filled with gas, it rises and closes the
valve e. As 80<m as the engine takes a charge of gas from

40 MANAGEMENT OF §23

the gasometer, the float b descends, and in doing so opens
the valve e far enough to replace the amount of gas con-
sumed by the engine. According to the existing conditions,
the pressure exerted by the weight of the float may be
increased by placing weights on top. The operator will
learn by experience just how far the dial cock on the engine
must be opened to make prompt starting possible.

65. Timing the Igrnitlon. — A very important feature
to be observed in starting an engine is the proper timing of
the igniting device. This of course applies more particu-
larly to electric ignition, as the hot-tube method is generally
automatic in its action and is not timed by any mechanical
device, but depends, for firing the charge at the proper
moment, on the diameter and length of the tube and the
temperature to which it is heated. Electric igniters are
almost universally equipped with a retarding device that
allows the breaking of the contact between the two elec-
trodes and the resulting spark to occur after the crank-shaft
has passed the dead center at the end of the compression
stroke and to thus prevent the engine from turning back-
wards suddenlv while the flvwheels are beincf turned bv
hand. It is therefore necessary to be sure that the igniter
lias been set in starting position, to avoid possible injury to
the operator. To lessen the liability to accident in case of
unexix^cted reversing of the engine while starting, it is
advisiible to avoid placing the foot on the flywheel spokes
when turning it by hand. If the engine is properly lubri-
cated, and the relief valve generally provided for the escape
ot a part of the compression pressure during starting is
working properly, it is always possible to turn an engine up
\o ;>(> horsepower by hand without putting the foot on the

S!H»kcS.

66. This prt^caution in timing the point of ignition
a:^v:iv s to electric i'^nition K^i the make-and-break contact as
we'l .IS t'e iump-spark methvxi. In the latter case, the
t-Tv.i-:^ vievicc. w'^ich n.\ctilates the moment of ignition,
ir.v.st be aviiusteJ so as to make the spark suflSciently late to

§ 23 STATIONARY GAS ENGINES 41

prevent reversing of the engine; hence a plainly visible
mark of some kind should be provided that will tell the
operator just how the timer must be set

In case of failure to ignite, first see that the vibrator of
the coil is working properly when the current is on. Also
detach the wire connected to the plug, and test the distance
the spark will jump by holding it close to any metal part of
the engine. In doing this, it must be remembered that a
spark will not jump as far when exposed to the high-com-
pression pressure in the cylinder as it will in the open air.
It should therefore be capable of jumping a gap of about
y\ to ^ inch when tested on the outside of the cylinder.

If the spark is found to be satisfactory, take out the plug
and examine the ends of the platinum wires, removing any
carbon deposit or other impurities that may have accumula-
ted there. Also see that the insulators are' in good order,
that they have not been cracked, and are free from grease ;
if necessary, cleanse them by washing with gasoline before
putting them back in the plug.

CAKE AND MANAGEMENT OP ENGINES

CARE OF ENGINE PARTS

67. In order to insure reliable service, an engfine should
be given the necessary care regularly. Those parts that con-
tribute principally to the proper operation of the engine, such
as the igniter, valves, governor, bearings, and lubricators
should be inspected at regular intervals.

IGNTTER

68. Under ordinary conditions of service, when running
about 10 hours a day, the igniter should be taken out once a
week, the contact points examined, and, if necessary, cleaned
or dressed. There must be no leak past the seat of the

42 MANAGEMENT OF §23

movable electrode, and as soon as any leak occurs at tMs
point, as indicated by a hissing sound, the electrode must
be taken out and ground to a perfect seat with fine emery
powder and oiL

The stationary electrode is usually insulated with mica,
porcelain, or lava washers or bushings, and packed with
asbestos, so as to make it tight against the pressure of the
explosion. If the packing of this electrode is damaged,
the steel pin itself will be exposed to the intense heat of the
burning charge. A gas leak will appear around the pin, and
when trying to overcome this by tightening the nut at the end
of the pin, the heated steel will be reduced in size. If this is
repeated a few times, the pin will soon be useless. It is evi-
dent, therefore, that the fixed electrode must receive particu-
lar care in regard to preserving perfect insulation and tight
packing. Mica insulators are probably best, as they are not
liable to cause short circuits and consequent interruption of
the service, by cracking, to which porcelain or lava bushings
are subject. They also have the advantage of being suffi-
ciently pliable not to require any asbestos washers to make
them tight.

POPPET VAL.VES

69. There should always be a clearance of about -^ inch
between the end of the valve stem and the lever operating it,
so as to make certain that the valve can come to its seat,
even after it has become expanded by the heat while in
operation. Repeated grinding will reduce the amount of
clearance, and adjustment must be made by slightly with-
drawing the setscrew usually provided in the end of the
lever.

Inlet valves are naturally kept more or less cool and clean
by the incoming mixture, and require grinding less frequently
than exhaust valves. Inspection and thorough cleaning
once a month, however, are advisable. Automatic inlet
valves, opened by the suction during the outward stroke of the
piston, must move freely in their guides; any deposit of

§23 STATIONARY GAS ENGINES 43

carbon or gummy oil will tend to interfere With their proper
working. Kerosene applied to all valve stems at regular
intervals will aid in keeping the stem clean and prevent it
from sticking. The nuts and lock nuts on the end of the
valve stem, which keep the spring in place, must be kept
tight Carelessness in this matter may cause the valve to be
drawn into the combustion chamber, where it may cause
serious damage to the cylinder or piston.

70. If the inlet valve is operated by cam and lever, the
same precaution as to a small amount of clearance between
the end of the stem and the lever must be observed, as
referred to in connection with the exhaust- valve stem. The
inlet- valve casing usually has in the cylinder head a ground
joint that requires the same care as the valve seat.

When using gas, the fuel valve operates under much the
same conditions as the inlet valve just referred to. The
same directions for cleaning and adjusting will therefore
apply to this valve. Gasoline poppet valves are often fitted
with small stuflSngboxes packed with wick saturated in a
mixture of soft soap and graphite powder. Care should be
taken to keep the stuffingboxes tight enough to prevent any
leakage of gasoline past their stems, but not so tight as to
prevent the springs from closing the valves promptly. It
will be found that a brass gasoline-valve stem will ^ve bet-
ter service than a steel stem, as the packing material has a
tendency to cause the latter to rust and stick.

GAS-COCK

71. The gas-cock, or throttle valve, generally consists
of a cast-iron casing, a brass plug, and a graduated dial, with a
handle to open and shut the cock. In order to be able to
move the plug easily, it should be lubricated occasionally
with a thin coat of oil and graphite. The screws that fasten
the dial to the body of the throttle valve and hold the plug
in position must be tightened evenly, so as to avoid leakage
of gas at this point. When using natural or producer gas.

44 MANAGEMENT OP § 23

which is usually not so pure as illuminating gas, it will be
found necessary to clean the gas-cock, as well as the gas-
valve stem and casing, more often. Kerosene will be f otmd
useful for this purpose.

OASOUNS PUMP

73. Owing to the fact that gasoline vaporizes easily, it
is more difficult to lift it by means of a pump than it is to
lift water. The condition of the gasoline pump is there-
fore of great importance in getting good results from a gaso-
line engine. The plunger must be packed well with suitable
material. Lamp wick or asbestos wick thoroughly saturated
with a mixture of soft soap and graphite has proved an excel-
lent packing for the stuffingbox of the gasoline pump. The
valves, whether they are standard-type check-valves or flat-
seated valves fitted with leather washers, must be kept free
from impurities that may lodge on the valve seats and cause
the pump to become air-bound, when it will naturally refuse
to work. Filters used in the gasoline supply pipe, before it
enters the pump, must be taken apart occasionally, and any
impurities that may have gathered there must be removed,
so as to afford a free passage to the fuel.

OOVTBBNOB

73. A steady speed is largely dependent on the working
of the governor and its attachments. TO insure good results
in this respect, the levers and links of the governor must
work freely, and at the same time there must be no lost
motion in any of these parts. A thin lubricating oil should
be used on all governor parts, and at regular intervals the
whole governor should be taken apart, its pivots, levers, eta,
cleaned by washing with kerosene or gasoline, and put
together again after applying a liberal amount of lubricating
oil. In most engines, the speed is adjusted by the tension
of the governor springs, a higher speed being obtained by
increasing, and a slower speed by decreasing, the tension of

S 23 STATIONARY GAS ENGINES

the springs. It is not advisable to increase the speed of an
engine beyond the normal number of revolutions without first
consulting the manufacturer.

SVABTTSn DEVICES

74. Self-Starters.^To obviate turning the flywheels
by hand, which in engines of the larger size would be incon-
venient, if not impossible, most builders equip engines of more
than 40 horsepower, and sonaetimes even smaller sizes, with
self-starting devices, consisting of hand pumps for compress-
ing the explosive mixtures in the combustion chamber, and
detonators or sparking devices for firing these charges by
hand.

In a gasoline engine, the charging pump is usually
attached to the aide of the cylinder and is fitted with a small
receptacle at the top or bottom containing a quantity of gaso-
line, over which the air is drawn before being forced by the
pomp into the cylinder. The air valve is automatic, and is
held to its seat by means of a spring, the tension of which
limits the lift of the valve and the amount of air pumped
into the cylinder.

The charging pump of a gas engine takes the fuel from
a small pipe connected to the gas supply, the gas being
mixed with air while entering the pump cylinder through a
series of email holes in the seat of the inlet poppet valve.
Before charging the cylinder, the detonator, if one is used,
must be charged with a parlor match, a portion of tlie
wood being removed so that only the head end is inserted in
the end of the detonator.

7S. In order to start the engine properly, it must be
turned until the beginning of the working or expansion
stroke is reached. At this point of the cycle, the engine has
just completed the compression stroke and the exhaust cam
is about 180° away from the roller that operates the exhaust
Valve, With the crank in this position, the mixture is
ftffced into the cylinder by giving a few quick strokes with

48 MANAGEMENT OF §23

smaller number of drops than when full, and it is therefore
well to always keep them filled. The temperature of the
engine room also has some eflfect on the rate of feed, and
in very cold weather the oil should be warmed before pour-
ing it into the lubricators.

Force-feed lubricators supplying oil through tubes to the
various bearings are more positive in their action in regard
to the quantity supplied under varying conditions. Care
should be taken, however, to guard against waste or other
impurities settling in the bottom of the reservoir, whence
they may easily be carried into the oil pipes and interfere
with the free flow of oil to the parts to be lubricated.

80. licvel of Oil In €rank-€ase. — In engines using
the splash method of lubrication the level of the oil in the
crank-case should be maintained at a uniform height, as
indicated by the gauge glass usually provided. While it is
necessary to keep the oil level sufficiently high to insure
good lubrication, it is equally important not to allow it to
become too high, because in that case the surplus oil is car-
ried past the piston, and is not only wasted but becomes a
source of trouble by depositing itself on the igniter points
and causing them to work irregularly. It may be observed,
however, that the fitting of each individual cylinder and
piston has some effect on the amount of oil thus carried into
the combustion chamber. It will therefore be found that
the oil level that must be maintained in order to get suffi-
cient lubrication of the piston may vary in two engines of
the same make and size, and in all cases great caution
should be exercised to carry the oil up to such a level that
there will be no doubt about sufficient lubrication. After
the proper level has once been determined by experience,
the oil gauge should be marked, so as to show at a glance
whether the oil is up to the required height.

81, Pressure In Crank-Case. — In some vertical four-
cycle engines that use the splash system of lubrication, the
escape of oil past the main bearings, due to the pressure

§23

STATIONARY GAS ENGINES

produced by the movement of the piston, is guarded against by
the use of a check-valve, a sectional view of which is shown
ia Fig. 9. The valve casing is attached to the crank-case,
and the valve a is made adjustable, the tension of the
springs b and c being
varied so that the valve
jost closes the port d
communicating with the
crank-case when the en-
gine is not running.
When the engine piston
moves downwards, the
increase in pressure in the
crank-caseopens the valve,
affording a relief for the
surplus pressure On the
upward stroke of the pis-
ton, the partial vacuum
closes the valve and pre
vents any air from being
drawn in.

82. Benewlnsr the

Oil. — The oil m the crank
case should ne\er be left "^'

more than a wtek without inspection Generally, it will
have become thick and unht for use by that time and should
be removed. If tliere is a leak of exhaust gases past the
piston, the oil in the crank-case will mix with the water from
the gases and may become charged with acid from the sul-
phur that is present in these gases. This must be prevented,
as the acid will gradually corrode and pit the journals of the
crank-shaft asd other moving parts with which it cornea in
contact.

50 MANAGEMENT OF §23

BOUnXB OF MANAGEMJEST

83« To avoid mistakes or oversights in starting, caring
for, and stopping engines, the operator should adhere to a
certain routine while performing his duties. The following
rules in regard to the order in which the various operations
in starting and stopping should be performed may prove of
value.

8TABTIKG THIS SN6INS

84. 1. Attend to all lubricators and oil holes, always
following the same order.

2. Apply a few drops of kerosene to the valve
stems.

3. Open the gas-cock back of the rubber bag or regula-
tor, or, when using gasoline, open the cock near the tank,
and work the gasoline pump by hand tmtil the liquid
appears in the valve or overflow cup.

4. See that the electric igniter is properly connected;
turn on the switch and see that the spark is of proper inten-
sity; or, in case of tube ignition, light the burner that
heats the tube.

5. Turn the flywheel until the engine is at the beginning
of the working stroke.

6. Open the fuel cock to the point that has been found
most reliable for starting.

7. Throw the relief cam in gear or open the relief
cock.

8. If a compressed air or some other self-starter is
employed, operate the device in accordance with the instruc-
tions given in pre\ious paragraphs relating to this style of
apparatus. If no starting devices are used, turn the fly-
wheels rapidly imtil the engine starts.

9. Close the relief valve or disengage the relief cam and
open t::e fuel ctx^k to its full extent, gradually, as the speed
of the e:iiri-<^ increases,

1«\ Tv.rr. o'l :;ie cvH.«'iir.Lr water, it running water is used,

§ 23 STATIONARY GAS ENGINES 51

or see that the tank is full and the cocks open if the tank
system of cooling is employed.

11. Throw in the friction clutch or shift the belt to the
tight pulley on the line shaft.

STOPPING THE ENGINE

85. 1. Disengage the friction clutch or shift the belt to
the loose pulley on the line shaft.

2. Close the gas-cock near the rubber bag or regulator,
or the gasoline cock near the storage tank.

3. Close the gas or gasoline cock on the engine.

4. Throw off the switch between the battery and the
engine, or turn off th^ burner that heats the tube.

5. Drain the water-jacket by closing the valve in the
supply pipe and opening the cock that connects the bottom
of the cylinder to the drain pipe. If water tanks are used,
close the cocks in the water pipe and open the drain cock.

6. Shut off all sight-feed lubricators.

7. Clean the engine thoroughly, wiping off any oil or
dust that may have accumulated on the engine.

8. See that the engine stops in a position where exhaust
and inlet valves are closed. If necessary, turii the wheels
by hand until this position is reached. It will protect the
valve seats against corrosion.

k <

•■

■ J

^ -^

TROUBLES AND REMEDIES

FATJIiTY OPERATION AND ADJUSTMENT

STMPTOMS, CAUSES, AND CORRECTIVBS

ENGINS-STABTING AND BUNNING DIFFICITLTrES

1. Defective action is sometimes due to causes so appar-
ent that explanations are unnecessary; hence, for the sake of
convenience, all these possible sources of trouble have been
grouped tmder the headings Causes of Refusal to Start,
Causes of Misfiring, and Causes of Weak Explosions.
In each case, the cause of the trouble may generally be
traced in the last analysis to faulty ignition, a faulty mix-
ture, or an insufficient supply of mixture. These broad,
ultimate causes have been stated first, and the principal
mechanical or electrical defects that produce the trouble are
enumerated afterwards. It will be understood that these
do not comprise all the possible troubles with engines. In
particular, they omit entirely such matters as preignition,
knocking, and overheating. The object of the following
presentation is to enable the user to trace the difficulty
when his engine refuses to give its normal power through
some trouble, the nature of which is not immediately
obvious.

3. It is a familiar fact that the internal-combustion
engine is far more liable to stoppages and weaknesses, for
reasons at first mysterious, than is the steam engine. The

QffytigkUdiaf JmUrmaUamai Textbook Company, Entered at Stationer fHali^ London.

■■•J

2 TROUBLES AND REMEDIES § 24

explanation of this is that, while the steam engine is purely
a mechanical apparatus, the internal-combustion engine is
partly mechanical, partly chemical, and generally partly
electrical in its functions, and the chemical and electrical
parts of its organism may go wrong through causes not con-
nected with the visible mechanism, or — as in the case of a
badly adjusted trembler, a poorly working timer, or a leaky
float — through mechanical derangements so slight as to
escape notice.

From this it follows that, to manage successfully, an
internal-combustion engine— especially one that works under
such a variety of conditions, often very severe,. as the auto-
mobile engine — it is first o^all necessary for the operator to
make good use of his reasoning faculties. The symptoms of
derangement, when taken singly, are often such as may
be caused by any one of several possible defects; in nearly
every case the defect, whatever it may be, will produce
several S)rmptoms a careful study of which will lead to the
elimination of causes that do not tally with all the symp-
toms ; as, for instance, causes affecting all cylinders when
only one or two are misbehaving, or vice versa. When the
user has reached this point, generally a short further inves-
tigation of the points at which he has found trouble of that
particular sirt is most likely to occur will lead him to the
discovery of the true cause. The cause of loss of power, due
to such faults as a loose battery connection, a sticking inlet
valve, or a bit of dirt in the carbureter, will at once be recog-
nized in its true character by the experienced operator. The
only way to attain final proficiency in these things is by
extended experience with the particular engine in hand; but,
on the other hand, there is absolutely no excuse for the aim-
less groping of many inexperienced users, who will often
send needlessly for a tow, or will pull an engine to pieces in
their search for some simple fault that might have been
located by intelligent diagnosis.

3, Causes of Refusal to Start, or of Sudden Stop-
pag:e. — The fundamental reasons for an engine refusing to

^ 24 TROUBLES AND REMEDIES 3

run, or of a particular cylinder refusing to work, may be
summed up as due to (1) no spark; (2) no mixture; or (3)
wholly wrong mixture. These cover all the possible causes,
which may be enumerated as follows :

1. Switch not closed.

2. Gasoline not turned on.

3. Carbureter not primed, or (rarely) primed too much.

4. Weak battery.

5. Gasoline stale or mixed with kerosene.

6. Gasoline too cold to vaporize.

7. Dirt or waste in carbureter or gasoline pipe.

8. Mud splashed into air intake.

9. Water in carbureter.

10. Soot on the spark plug or contact igniter.

11. Water on spark plugs.

12. Broken spark-plug porcelain.

13. Grounded wire (generally secondary).

14. Broken wire (generally primary), or loose connection.

15. Very bad adjustment of *the coil tremblers.

16. Defective spark coil or condenser (rare).

17. Broken igniter spring.

18. Broken valve stem, spring, or key.

19. Valve cams slipped (rare).

4. Causes of Misfiring:, — The principal cause of mis-
firing is irregular sparking, which may be due to a variety
of causes. Irregular sparking may be caused by the
following:

1. Soot on spark plugs or contact igniters.

2. Weak battery.

3. Broken wire, making intermittent contact through
the vibration of the car (generally found in the primary
circuit).

4. Loose connection to binding post (generally found in
primary circuit).

5. Wire occasionally grounded through vibration of car.
This is generally found in the secondary circuit, and it is
not necessary for the bare wire to make contact with the

4 TROUBLES AND REMEDIES § 24

metal into which this secondary current is escaping. If the
insulation of the secondary cable is weakened, and the cable
is lying loosely on a metal part, the spark will often jump
through the insulation.

6. Timer contact surfaces roughened by sparking.

7. Wabbling timer.

8. Poor trembler adjustment.

9. Trembler sticking at high speeds, due to inertia of
heavy armature.

10. Insuflftcient pressure on timer contacts.

A sticking inlet valve, which stays open when it ought to
close, will cause irregular firing and occasionally back firing.
Another possible cause is a very lean or rich mixture ignit-
ible only by a strong spark. It can always be distinguished
from ignition troubles by the fact that the explosion
impulses, when they occur, are of much less than normal
strength. If the mixture is too weak, the explosions are
likely to occur every other cycle.

5. Causes of Weak Explosions. — The causes of the
explosions being weak are as follows:

1. Mixture too lean or too rich.

2. Leakage of compression.

3. Mixture diluted by exhaust gases.

4. Spark timing later than it should be, in one or all
cylinders.

If the trouble is in the mixture, the explosions would be
regular, unless the mixture is so far defective that it some-
times fails to ignite in spite of the spark occurring regularly.
The same will be true in any case where, as is usual, the
cause of the weakness is unconnected with any irregularity
in sparking. '

The principal causes of weak explosions may be enumer-
ated as follows :

1. Dirt or waste in carbureter or gasoline pipe, causing
weak mixtures.

2. Stale gasoline.

3. Air intake partially obstructed, causing rich mixture.

§ 24 TROUBLEvS AND REMEDIES 5

4. Bad carbureter adjustment.

5. Trouble with float.

6. Choked muffler.

7. Lack of oil on piston, or too thin oil.

8. Leak through valve (generally the exhaust valve).

9. Leaky spark plug.

10. Valve timing wrong. This is most likely due to
the fact that the cam-shaft, etc., have been taken out and
replaced with the gears in incorrect angular relation. It
may, however, be caused also by wear of the cams, push
rods, or valve stems, by spring in the cam-shaft or valve
lifters, or by the slipping of cams.

11. Broken or worn piston rings.

6. A two-cycle marine engine may be running along
smoothly and begin gradually to slow down. This condi-
tion may be caused by too much or too little gasoline; the
ignition devices may have become disarranged ; there may
be too little cylinder or other lubrication, or too little water
circulating through the cylinder jacket; something may be
caught in the propeller wheel ; in cool or cold weather, the
moisture in the atmosphere may have become frozen by the
rapid evaporation of the gasoline, thus preventing the free
flow of air or the proper seating of the valve in the vapori-
zer controlling the. gasoline supply and the flow of mixture
from the crank-chamber ; the piston and rings may have
been fitted too snugly, causing them to bind in the cylinder,
which may have become distorted by the different tempera-
tures to which it is subjected, there being a comparatively
cold inlet on one side of the cylinder and a hot exhaust port
on the other; the exhaust ports, piping, or muffler may
have become partly stopped by water, carbon, salt, or other
deposits; the exhaust may have been submerged by a differ-
ent trim of the boat, or there may have arisen conditions
such as could not have been foreseen or provided against,
and that might never again be experienced. At any rate,
such slowing down is a forerunner of trouble and should
be investigated. If the cause of the trouble cannot be

168~-28

6 TROUBLES AND REMEDIES g 24

discovered, the engine should be stopped when it ii^ safe to
do so, the position of the boat being made such as not to
endanger either boat or occupants through collision with
passing craft.

7. The remedies for slowing-down troubles due to the
causes just mentioned will in practice suggest themselves.
In many cases, the cause of the difficulty can readily be
determined and overcome. For instance, trouble due to an
insufficient quantity of cylinder oil or circulating water
might be attended to readily without stopping the engine,
or a temporary stop might be made to remove a rope, grass,
etc. , from the propeller, or foreign matter from the sea-cock
strainer or pump check- valves, or to adjust the ignition or
replace a broken or weak valve spring. Structural troubles,
such as tight pistons and distorted cylinders, would have to
be attended to at some more opportune time.

If the vaporizer should freeze, it may be necessary to run
the engine a while and then give the accumulation of ice and
frost a chance to melt If the water supply is insufficient
and the jacket becomes overheated, it may be possible in
case of an emergency to continue running by using a hand
pump connected with the supply ; or, with the supply open
water may be pumped through or poured into the water dis-
charge. In such case, the transformation of the water into
steam might make it a little dangerous for the operator, and
should the cylinder be too hot the water might possibly
crack the cylinder at its weakest part, or at the point where
it is subject to the greatest. stress.

When it becomes necessary to run a four-cycle marine
engine with too little circulating water, the compression
should be relieved, the cooling action of the large quantity
of gas, a part of which is wasted, helping to cool the cylin-
der, while the smaller amount exploded does not heat the
cylinder as much as would full charges at the usual high
compression pressure.

8, Irregular running of marine engines is a condition
rarely encountered, and its cause is problematical. The

g 24 TROUBLES AND REMEDIES 7

trouble may be caused by back pressure in the exhaust, or
may be due to improper location, with reference to the
exhaust port, of the transfer, or passover, port connecting
with the crank-case; this could occur only in two-cycle
engines. As a result of such improper location of the port,
the engine cylinder might not be thoroughly scavenged of
burned gases at high speed, when it would slow down to
normal speed or slightly below, and, getting a better mix-
ture at that speed, would speed up. It might also be
caused by the exhaust ports opening too late or the inlet
ports opening too early. It is well known that, with no
thought of fuel economy, two-cycle engine ports should
open much earlier when designed for high than for low
speed, in order to more thoroughly get rid of the products
of combustion. When it is discovered that the engine is
being run at a speed in excess of that to which it is best
adapted, the remedy is to make the ports open earlier, or hold
the engine to slower speed by increasing the diameter, pitch,
or blade surface of the propeller.

Should the engine, without missing explosions, begin to
increase its speed, and then miss explosions and slow down,
one wbuld naturally be led to suppose the cause of the
trouble to be insufficient length of contact of the sparking
device as well as poor scavenging of the cylinder.

Trouble from loss of compression in the combustion cham-
ber, whether in a two-cycle or a four-cycle engine, must be
renledied before the engine can be made to run satisfac-
torily. If, in attempting to start, it is found that therp is
no compression, the valves should be examined to see if
they seat properly and are timed correctly. Loss of com-
pression may be caused by a leaky gasket, allowing the
pressure to leak into the water-jacket, which is the first
place to look for the cause of trouble after examining the
valves. A leaky gasket may sometimes be discovered by
noting whether or not pressure escaping into the water-
jacket shows at the water discharge.

TROUBLES AND REMEDIES §24

KNOCKIXG, OK POUXDIXG

9, Undoubtedly the sense of hearing is more useful in
detecting irregularities in the running of an engine than any
other sense. By means of the sounds produced, the engine
talks to the operator, and with a little intelligent study he
will soon understand the language. Even at a distance it is
often possible to tell whether an engine is running regu-
larly or whether, as indicated by the sound of the exhaust,
some of the charges admitted to the cylinder are expelled
without being exploded. Standing in close proximity to
the engine, the operator may distinguish a variety of sounds
indicating defects about the engine and calling attention to
the necessity of applying proper remedies at the first
opportunity.

A sharp, knocking soimd in stationary engines may be
due to any one of the following causes:

1. Lost motion in the bearings of the connecting-rod,
either at the crankpin or the piston-pin end.

2. Lateral movement of a piston ring, the groove in the
piston having become widened by wear.

3. A loose key in the flywheel or pulley,

4. Lost motion in the gears, causing the gear-shaft to be
retarded in its revolution for a fraction of a second when the
exhaust or inlet- valve cam hits the roller and lever.

5. Piston or cylinder worn to a considerable extent,
causing an up-and-down movement of the piston.

G. The piston having worn a shoulder in the bore of the
cylinder, and striking the shoulder if any play in the bear-
ings is developed.

7. The piston striking any foreign body that may acci-
dentally have been drawn into the cylinder.

10. Knocking in automobile engines may be due to
looseness or rattle in some external part, owing to nuts hav-
ing worked loose or to bolts being sheared off or being too
small for their holes. Knocking due to such causes is readily
detected by a careful inspection while the engine is runningi

§ 24 TROrBLES AXD REMKl^lKS t^

and this inspection may be aided by l^xnn^^ the l>;^^v1^ tM\
parts scspected of bein^ loose, when vibration wUl t\^Mlv
be felt; also by careful scraiiny with an elcottio tU^hli)iht
for evidences of movement where t\\x> jvarts aw l>\>lte\l
together.

Abont the most likely place to tmd hxxsoncNS of thi»
description is in the holding^-down lH>lts that hold tho onj^ine
to the frame on which it is mounted; but in vvrtrtin hon^on-
tal engines it may also be found that the ea^vs owr the nmin
bearings are loose, owing to the fact that ihey hnvx* not
been properly tongued into the bi>tlv>ni halXTH or pillow-
blocks of the bearings. Looseness at cither of thoso l\\*i>
points should be remedied at the ix^pair slio|\ «» H alwayw
necessitates the substitution of larger l)«>lls, aiOeil perhaps
by dowel- pins; and in the case of the ])earing rap it tnay hi»
necessary to make a wholly new cap, witli prnpor tnn|itu»«
fitting into grooves that must be luavhiiKMl or rhlmOnl In
the pillow-block.

11, A. more probable cause of knocl^inj^ Im Immmimu^mm iIim*
to wear in the main-shaft bearingH, iTankpIn br/itln^M^ n\ \\\i*
wristpin bearings. In a four-cylinder veillral ««n^lm*, I In*
main-shaft bearings may be quite Inn^r wilhont (Mimhiy n
knock, because the weight of the nhaff and IIvwIm*! IioMm
the shaft down; but a horizontal cnj/itie will, nnd^'f ifiUilu
conditions of speed and lo^id, |x>nnrl with a ftfriall afrioimf of
looseness. Only a very limited amount tff |/»oi•^'r^^•Ji^ Mh^^nld
be permitted in the main-«^haft l^^iarin;^*; fff nuy ^nJ/lrf^. \tt,fU
on account of the danger of ^^fT')u*^\u^ fh'- ^\\)i\U /»nd fr' Offi*'>-
a bearing worn beyond fh:^ ^ixu-ui i«; li/iM/ to t/z-^ln / nttiff^,
as it is difficult v> kee:> =Jiffj' v-.* oil ;ri it

12. LoosenetiH :r. *''c ?":/■• K^'/i M;irM.;/ t,f n '//-rfi/Tfl
motor is di:scIo*^''! V/ y.** -.-^ ;» ;,./ > \r,At r tf,/- n/«/ii//| ,»rid
working it gently : ^ >r.\ '.v»" T , ♦;./■ ' .^.y /rf ,» K/r7i//fTrMI

engine it IJ^ r.eCli?*'^'/ V--, ',- ' * ^ .'S.-»f' .;f;f;/r/ifMri»/.i / ^^^

line with the or*:<i-if:*', ^•' * '. ^ / , -^z -^/-." rn.o .» i/^ //•!• «/,;i b-f^/^
tobeapplied v* * »; ■^■i'*-/ ,- :•..%' ., v*,^»^/«''' r nr»f»M' i*
seems most pract:iv«'/»* ^y.-.^^^f^.. / ^^/'/-o'v^^ <rf «o'* ^»i'»f'

10 TROUBLES AND REMEDIES § 24

can be detected by rocking the fljrwheel back and forth
against the compression in the cylinder. If the pull of the
sprocket chain comes on the engine shaft, it may be possible
to detect looseness in the adjacent bearing by alternately
stretching and relaxing the chain, which can be done by
grasping it midway between the sprockets and pulling it up
and down as far as it will go.

Another very good way to disclose looseness in the main
bearings of any car having a planetary transmission gear on
an extension of the engine shaft is to tighten one of the
friction bands of this gear by the appropriate lever, usually
the low-speed or reverse lever. It is very rarely that the
tension of these bands is exactly balanced, so as to impose
no radial pull on the shaft, and tightening the band will
move the shaft to whatever extent the adjacent bearing has
worn. «

A novice should not attempt to refit the main-shaft bear-
ings, as this requires a good deal of skill and experience for
its correct execution.

Wear in the crankpin bearings is disclosed by setting the
cranks at about half stroke, and rocking the shaft back and
forth.

13, Knocking in the wristpin, due to wear of the pin and
its bushing, is not among the commoner troubles, and it
does not need to be attended to at once unless aggravated.
It is well, however, not to neglect it too long, as the bush-
ings and the pin will be worn out of round, so that they can-
not be used. A good engine will run a car several thousand
miles before any replacement is demanded at this point.
When it is taken out, the wristpin should be calipered
all around. If it is out of round, it should be ground
true; or, if this is impracticable, a new pin will have to be
supplied, and the bushing reamed or scraped to fit. This,
of course, should be done in a repair shop.

14, A cause of knocking occasionally found is due to the
wristpin and the crankpin not being quite parallel. This
causes the connecting-rod to oscillate from end to end of the

§ 24 TROUBLES AND REMEDIES 11

wristpin and crankpin bearings; and if, as is customary,
there is -^ or more of end movement in these bearings, the
knocking may be quite noticeable. If, as is likely to be the
case, it is impossible to make the pins parallel, the only
recourse is to take up the lost motion at the end of one or
the other bearing, and possibly both bearings, by the use of
washers or cheeks soldered to one end of the bushing and
brasses. This is not a common cause of knocking, particu-
larly in the better class of engines.

16. The best construction is to secure flywheels to short
shafts by bolting them to flanges instead of keying them.
Sometimes, however, a flywheel is held on by a common
key, or by two keys 90® apart, and frequently it will work
loose on its keys. This will inevitably result in a knock,
which will be very loud if the engine has less than four
cylinders. The crank-case should be opened and the cranks
blocked so that the shaft cannot turn, and then force should
be applied to the flywheel to disclose the looseness, if any.
Sometimes the flywheel will be so tight on its shaft as to
resist turning in this manner by using any ordinary force.
In this case, it is best to take the car to a repair shop if a
thorough search has failed to disclose any other cause for
the noise.

A sprung shaft will always cause knocking, and also rapid
wear and cutting of the bearings.

16. Besides the foregoing mechanical causes of knock-
ing, there is a class of what may be called combustion knocks
that are altogether distinct from the preceding, in that they
may occur without appreciable looseness in the bearings,
and are due to excessive rapidity of combustion, coupled
generally with too-early ignition, the charge being com-
pletely burned before the piston has reached the end of the
compression stroke. Combustion knocks are due to a vari-
ety of causes, the most obvious of which is simply too-early
ignition, as when running up a hill without suitably retard-
ing the spark. A contributing cause is a slightly weak mix-
ture, since such a mixture bums faster than a normal or

12 TROUBLES AND REMEDIES § 24

overrich mixture. Pounding in particular cylinders of a
multicylinder engine may be due to unequal rapidity of com-
bustion, which itself may be due to unequal charges, as
when the valves are unequally timed, or to irregular spark
timing, such as may result from a wabbling timer or badly
adjusted vibrators. If the timer contact surfaces have been
roughened by sparking or by wear, they will cause the con-
tact maker of the timer to jump when running fast, and
therefore to make erratic contact, resulting in irregular
firing.

17. The classes of combustion knocks just mentioned
are easily traced to their causes. The knocks are not neces-
sarily violent, and they may sound a good deal like the
knocks due to loose bearings, except that, if caused by
faulty action of timer or vibrators, they will occur irregu-
larly instead of regularly.

There is, however, another and very common sort of
knocking due to spontaneous ignition of the charge before
the spark occurs. This may be caused by overheating of
the motor from lack of water or other trouble with the cir-
culation — a trouble at once indicated by boiling of the water
in the radiator or by smoking of the exterior of the motor.
It is a temporary phenomenon, and involves no harm to the
motor if the latter is promptly stopped and allowed to cooL

18. Much more troublesome, and also more common, is
spontaneous ignition, or preigrnition, as it is termed, due
to a deposit of carbon in the combustion chamber or on the
piston head. A carbon deposit of this nature maybe caused
by too much gasoline or by too much cylinder oil, and it
will accumulate gradually even with the carbureter and
lubrication correctly regulated. A small quantity of carbon
will give no trouble, but as the deposit thickens some por-
tions of it will remain incandescent from one explosion to
the next, and will ignite the fresh charge at some point in
the compression stroke, depending on conditions. The fact
that the charge is not ignited until some time during com-
pression is due to the fact that the more highly it is

§ 24 TROUBLES AND REMEDIES 13

compressed, the more easily it ignites. True preignition
results almost always, except at the highest engine speeds, in
the charge being completely burned before expansion begins,
and it is easily distinguished, especially if the engine is
taking full charges, by the resulting sound, which is a sharp,
metallic bing! bing! bing! closely resembling that produced
by a hammer striking a block of cast iron. Usually, though
not always, an engine that preignites in this manner will
continue running by spontaneous ignition for some seconds
after the igniter switch has been opened. The hammering
due to preignition, as would be expected, is most marked
when the engine is running slowly with the spark suitably
retarded, and it will generally manifest itself when hill
climbing, owing to the fact that the throttle is then wide
open and the spark necessarily retarded to suit the slow
speed of the motor.

19. In stationary engines, a heavy, pounding noise, such
as is caused by premature ignition, may also be due to exces-
sively high compression for the grade of fuel employed. In
addition to its initial effect in producing a pounding noise,
either preignition or a too-high compression pressure may
cause the piston to expand unduly and to stick in the cylin-
der, which it would not do if the conditions were normal.
This sticking of the piston would produce a knocking sound
due to the small amount of play in the connecting-rod bear-
ings necessary for smooth running.

A coughing or barking sound is caused by the escape of
pressure past the piston, and would indicate the necessity
either of replacing any worn or broken piston rings or of
reboring the cylinder and fitting a new piston.

With marine engines, a loose coupling may cause a pound,
as may also a loose propeller wheel, but these pounds can
easily be located.

14 TROUBLES AND REMEDIES § 24

CYIiIin>ER AXI> PISTON DISORDERS

20. Scored and Ijeaky Cylinders. — One cause of scor-
ing* of the cylinder lies in the fact that the ends of the piston
pin or wrist pin when loose sometimes protrude through
the hole or bearing in the piston. Some pins have their
bearing in the piston itself, while others, being tightly
secured in the piston, have their bearing in the upper end of
the connecting-rod. No matter which construction is
employed, the ends of the pins should never come in contact
with the cylinder walls. The pin must by some absolutely
positive method be kept in place. While a loose wristpin
is often the cause of a scored cylinder, there are three other
causes, resulting from imperfections of design or of machine
work, to which scoring can be traced ; namely, loose core
sand, imperfectly fitted piston rings, and loosening* of the
pins that are used to prevent the piston rings from turning in
the slots in the piston.

2 1 • Trouble from loose core sand is due to sharp sand that
usually comes from the cored passage connecting the crank-
case with the inlet or passover port to the combustion cham-
ber of two-cycle engines. With cylinder castings prop-
erly pickled in dilute sulphuric acid to remove the sand, this
trouble would not be experienced ; but with modem methods
of cleaning castings by means of the sand blast, the cored
passages are frequently neglected. Some engines are pro-
vided with a removable plate over the inlet port, for the
express purpose of making sure that there shall be no core
sand therein to cause trouble.

If, in an engine of the two-cycle type, the scoring consists
of several parallel marks on the side where the inlet port is
located, it is safe to ascribe the trouble to sand. If the scor-
ing is on the exhaust-port side, it is usually an indication of
insufficient lubrication ; as the hot exhaust gases pass out
they burn the oil off that side of the piston and cylinder, the
exhaust side of a two-cycle engine cylinder being always hot-
ter than the inlet side. Scoring may occasionally be due tu

§ 24 TROUBLES AND REMEDIES 15

the presence in the cylinder of pieces of the porcelain insula-
tion of spark plugs. Cylinders have been practically ruined
through dropping into the cylinder the pin or nut holding in
place the spring on an inverted inlet valve.

23. Leaky cylinders — particularly in two-cycle engines
— render the wristpin, crankpin, and main-shaft bearings
subject to excessive wear, because the heat of the gases that
pass by the rings into the crank-case tends to bum up the oil
and heat the bearings. If the engine is of the two-cycle
type, the leaking products of combustion not only foul the
fresh charge of gas so Ihat it is not so explosive, but the
quantity of each charge is reduced.

If, in an engine in which the inlet and exhaust valves are
tight and there is no leaky gasket, it is found that the com-
pression has become materially reduced, the trouble is proba-
bly caused by leaks from distorted, scored, or imperfect cyl-
inders, the pistons or piston rings being worn considerably or
stuck in the slots in the piston. The only remedy is to
remove the pistons for examination.

If the cylinder is found to be out of round or scored, it will
have to be rebored, and new pistons and rings fitted. If the
rings are found to be rusted or stuck in the slots, they will have
to be removed, even if to do so it isnecessary to break them.
They may have worn to such an extent that the openings at
the points of parting are such as to allow a loss of pressure,
the leaking charge passing either into the tight crank-case,
if the engine is two-cycle, or into the atmosphere. If such
leakage^ is not stopped, the heat of the escaping gases will
bum the oil out of the crank-case, and the bearings will soon
become badly worn, if not ruined.

33. The piston should be examined carefully for wear.
The side on which the angular pressure of the connecting-
rod is exerted should, of course, show the most wear. If
the front or rear side of the piston shows wear at top or
bottom, with a corresponding amount of wear on the oppo-
site bottom or top, it is proof that the hole through the
piston for the piston pin, to which is connected the upper end

16 TROUBLES AND REMEDIES §24

of the connecting-rod, is higher at the end showing wear at
the top of the piston than at the end showing wear at the
bottom. If this is found to be the case, and the wristpin is
tightly secured in the piston, the connecting-rod bearing for
the wristpin will be found to have worn badly and will be
bell-mouthed, that is, larger at the ends than at the center.
The remedy for this is to true up the hole carefully and bush
it, or use a pin that is a trifle larger than the hole, increasing
the size of hole in the upper bushing slightly. This is a
repair job that should be entrusted only to a thoroughly relia-
ble machinist having the tools and means for doing accu-
rate work. Side wear on the piston is much more likely to
show in engines having the wristpin held securely in the
upper end of the connecting-rod, the ends of the pin having
bearings in the piston. •

24# Piston rings become stuck in the slots in the piston
from two causes ; namely, from water getting into the combus-
tion chamber, causing the rings to rust, and from the sides
of the slots being slightly tapered instead of parallel. Where
tapered sides are found, it is usually necessary to straighten
them up in a lathe and use slightly wider rings. Piston
rings should be renewed much oftener than is customan^
As they become more and more open at the ends, the hot
gases passing by the ends of the rings have a harmful effect
on the polished cylinder surfaces, and in two-cycle engines
they foul the mixture in the crank-case.

25. Broken piston rings, particularly in engines with
ports that are opened and closed by the pistons, are a source
of annoyance, and frequently cause much trouble. Broken
piston rings are frequently the result of insuflficient care in
putting the piston, with the rings in place, into the cylinder,
but are more likely the result of getting a ring end caught
in a port. To prevent this, two-cycle engine rings are usually
pinned to prevent them from turning until the ends can get
into the port.

The breaking of a piston ring is rather an unusual occur-
rence; it will cause loss of compression, that may be

§24

TROUBLES AND REMEDIES

disdnguished from leakage due to the rings being worn by the
fact that the broken ring will make a distinct clicking sound
at the end of every stroke. It will also be found that oil
squirted on the piston when a ring is broken will not stop the
Leak. If the engine has more- than one cylinder, it is prob-
able that loss of compression due to lack of oil would affect
all the cylinders, whereas a broken ring affects one only.
If a piston ring is broken, it becomes necessary to take off
the cylinder without delay and put in a new ring.

26. Piston rings are supposed to be held in position by
small pins, one in each
ring, so that the joints of
adjacent rings are diamet-
rically opposite. If for any
reason these pins break, a
ring may slip roimd until
its joint is in line with
that of the next ring above
or below. This will cause
loss of compression that
may be very puzzling; it
is an unusual occurrence,
and it may be necessary to
take off the cylinder to
locate the trouble.

37. A good method
for pinning piston rings is
shown in Fig. 1 {a) and (^).
Fig. 1 {a) is a diagram of
a piston head, the dotted
lines showing the bottom
of the ring slot, while Fig.
1 (d) is a sketch of a por-
tion of one side of the
piston. With the piston square on its lower end, drill, at a,
a point about half way between the inlet and exhaust ports,
through dy r, and d, a hole large enough for clearance for a

18 TROUBLES AND REMEDIES § 24

small tapy continue the hole into e with a tap drill, tap the
hole, and screw into it a slotted screw to extend into the slot
for a distance not quite one-half the width of the slot. Then
tap and plug the hole through ^, r, and rf with screws dipped
in muriatic acid to rust them in place, the screw plugs being
in each case below the surface of the slot faces. At another
point, where it would not come opposite a port, drill a hole
through b and c and tap into //, plugging the clearance holes,
as before. Drill at another point a hole through ^, tapping
into c. The slotted screws extend one-half or less the width
of the slots from the bottom, so that, if the rings be
parted as in Fig. 2 {a) one of the ends could be cut off
slightly to receive the pin, or, if parted diagonally, as in

, Fig. 2 {b\ a space could be cut out

1 for the pin. With this method of

^^) pinning the rings, there is no way for

the pins to work out to score the cyl-
inders. While it is customary to pin
the piston rings for two-cycle engines,
(^^ pins are rarely found necessary in

^'°* ' four-cycle engines, as such engines

have no ports to catch the ends of the rings, except when an
auxiliary exhaust is employed.

2 8 . Cyllndep-Packlnfif Troubles. — The joints between
the cylinder head and the cylinder of stationary gas engines
are kept tight by packings usually cut out of asbestos
sheet about -^ inch thick. When the packing is dam-
aged by overheating or excessive pressure, water from the
jacket leaks either to the outside or into the cylinder. The
latter is the more serious leak of the two, as it interferes
with the running of the engine by corroding the points of
contact on the igniter and the valve seats and stems, and
prevents proper lubrication of the piston and cylinder. Leak-
ing toward the cylinder is generally indicated by splashing
of the cooling water at the overflow pipe when the explosion
tfl.kcs place.

In most cases, the blowing out of a packing is caused by

§ 24 TROUBLES AND REMEDIES 10

the combustion pressure opening the joint between the
packing surfaces, the packing being heated and partly
destroyed, and allowing water to enter the combustion
chamber. A partial or complete stoppage of the cooling-
water supply or the clogging of the water spaces with lime
or similar deposits will also result in the overheating of the
cylinder and consequent damage to the packings.

As soon as a leak of water from a faulty packing develops,
preparations should be made to renew the packing at the
first opportunity. If the leak is to the outside, which may
not interfere with the operation of the engine, although it
will cause inconvenience through having to catch the water
in buckets, it is not necessary to shut down the engine until
the day's work is done. If the leak is toward the combus-
tioil chamber, the engine will generally stop in a short time.

29. Most automobile engines have the cylinder heads
and cylinders in one piece; but a few engines have copper
or aluminum water-jackets. There are, however, some old
engines with separate heads still in service. In some cases,
the cylinder heads, when separate, are made a ground fit on
the cylinders, but they are commonly made tight by asbes-
tos gaskets. Leakage through these may be detected some-
times by the soimd, and sometimes by putting a little oil
over the suspected place and noting the resulting bubbles
when the crank is turned.

In case a cylinder-head gasket leaks, it will be necessary
to put in a new gasket. The head should be taken off,
the old gasket removed, and the iron surfaces in contact
with it should be carefully scraped clean. The new gasket
may be of sheet asbestos, and it should be sprinkled evenly
with powdered graphite to prevent it from sticking. It
may be cut to size by laying it on the cylinder and tapping
it lightly with a small hammer to indicate the outlines.
Care should be taken not to let inwardly projecting edges
interfere with the valves or igniters; and, also, if there are
openings througfh the head for the passage of water, it
should be seen to that these are not closed, by the asbestos.

20 TROUBLES AND REMEDIES § 24

A good packing for cylinder heads is sheet asbestos with
woven brass wire embedded in it. This packing is much
^^tronger than ordinary sheet asbest6s, and will not blow out
•jnless the cylinder-head bolts are loose or the head is a bad
lit In replacing a cylinder head, the bolts should be tight-
ened gi^adually and evenly, each being tightened a little at a
time, and the round being made three or four times, so as
to ^void localizing the stress on any one bolt.

There is, of course, but one remedy for leaky gaskets,
namely, renewal. The old gasket should be carefully and
completely removed, and by means of a straightedge a care-
ful examination should be made to discover, if possible, why
the gasket gave way at a particular point. There may have
been insufficient surface or too little holding-down pressure
to keep the packing in place ; the studs may have been too
fa. apart at the point of rupture, or the nuts may not have
been tightened after the engine had become heated.

VAI^VE DERANGEMENTS

30. Lieaky Inlet and Exhaust Valves. — Trouble from
loss of compression in the combustion chamber, when the
spark plug is tight and there is plenty of oil on the piston,
is generally due to leaky valves. In order to determine
whether the leak is in the valves or in the piston rings, a
moderate quantity of oil may be squirted through the com-
pression relief cocks and the crank turned two or three
times, which will temporarily check whatever leakage there
may be around the piston. If the compressed charge still
escapes, the inlet valve, if located over the exhaust valve,
may be taken out and examined. The leak, however, is
much more likely to be in the exhaust valve.

To take out the exhaust valve, turn the engine over by
hand, with the switch off and the compression relief cocks
open, until the valve is opened. Then prop up the valve
spring with two pieces of wood or brass ^, «, Fig. 3, cut to
the proper length to go between the spring collar by and the
upper end (or lower end, if this is more convenient) of the

S24

TROUBLES AND REMEDIES

Pig. 8

push-rod guide c, and turn the engine again until the push
rod d is down as far as it will go. Push the exhaust valve
down; the key at e may now be slipped out. If the props
have been made accurately to length, the
valve may be slipped up and out, leaving the
spring and the collar in place. Inspection
should show the valve seat to be of uniform
appearance all the way around,, and dull — not
glossy. If the seat of either valve is pitted
or rough, or if it is worn bright on one side,
showing that it has been seating only on that
side, it should be reground.

31. The remedy for leaky valves is to
reg^nd them to their seats. If badly scored
and worn, which will be shown by a blacken-
ing of the seat and valve, it may become nec-
essary to reseat and true up the valve, but if
the engine has had ordinary care and attention, grinding
should be sufl5cient For this purpose, the exhaust valves
may need emery and oil, finishing up with powdered oilstone,
ground glass, silex, or the dirt that accumulates under a
grindstone. The valve should not be rotated its whole cir-
cumference — as is frequently done, using a brace or breast
drill with a bit screwdriver — but should be rotated a little,
first in one direction and then in the opposite direction, rais-
ing it off the seat very often, and using oil freely, until a dull
surface appears on both the valve and the seat throughout
their bearing surfaces. Rotating the valve rapidly is very
likely to cause grooves and ridges that are extremely hard to
remove and make the valves tight.

While there is little or no danger of getting emery or
other abrasive substance into the cylinder when grinding
exhaust valves, ordinary care to avoid doing so should be
exercised. The passage of the products of combustion
being outwards, such matter would be carried away from
the cylinder. Grinding the inlet valves is a very particular
operation, for any particles of abrasive substance left behind

168—24

22 TROUBLES AND REMEDIES § 24

to be drawn into the cylinder are liable to cause trouble.
All traces of grindstone dirt, which will be found well
adapted for grinding and may be mixed with water instead
of oil, should be wiped off carefully.

The valve stems should be inspected, and, if rusted or
rough, should be cleaned and smoothed, a few drops of
kerosene being applied to cut any deposits that may have
accumulated in the guides.

33. Weak or Broken Inlet-Valve Sprinsr* — Some-
times the inlet- valve spring, especially if the valve is of the
automatic variety, will weaken from becoming overheated
This is almost sure to occur if the engine has been allowed
to overheat from lack of water. In time a spring loaded
too near its elastic limit will break from the jarring to which
it is subjected. The symptoms in either case are loss of
power at high speeds — although the power may still he
ample at low speeds — and clattering of the valve and blow-
ing back in the intake pi{)e at high speeds. The latter
may easily be detected with a single- or double-cylinder
engine by holding the fingers close to the air intake, when
the backwards puffing will be very perceptible. If the
engine has four cylinders, it may be possible for the inlet-
valve springs to be slightly weak without the mixture blow-
ing back at the intake, owing to the fact that one or another
cylinder is aspirating all the time, and the air expelled from
one cylinder is drawn into the next. One way to get
around this difficulty is to block open the exhaust valves of
two cylinders — the first and fourth or the second and third-
while the others are tested. It will probably be simpler,
however, to experiment with the valve-spring tension. If
the valve spring is weak, and if it is temporarily increased
in stiflEncss by putting washers under it to compress it, a
marked increase in the power of the motor at high speeds
will be observed. The proper remedy, however, is to put
in a new spring, or, if this cannot be done, to stretch the
old spring. For a valve lift of ^ inch, and for average
engine speeds, the tension should not be less than 1 pound

§ 24 TROUBLES AND REMEDIES 23

per ounce of the weight of the valve, washer, and key. The
engine will work better if the springs arc a little too stiff
than if they are not stiff enough. There will also be less
danger of breakage of the valve stems and keys.

33. Unequal Tension of Automatic Inlet-Valve
Sprtn^s. — The effect of unequal tension in the springs of
automatic inlet valves is to permit one cylinder to take more
gas than another. Consequently, at slow speeds the cylin-
der whose valve spring is weak will get the larger charge;
and at high speeds part of the charge will be blown back
through the valve whose spring is weak, so that the other
Cylinders will get stronger impulses. A quick way to test
the equality of valve-spring tension without taking out the
valves is to run the engine slowly with the throttle almost
closed. This will cause the cylinders whose springs are
stiffer to receive scarcely any gas, and the cylinders whose
valve springs are weak will do most of the work. It is
possible, however, to go to excess in a test of this sort,
since, when a motor is running light with the minimum
quantity of gas, one cylinder is almost sure to get more gas
than another, if the inlet valves are automatic, even with
the most careful equalizing of the springs. If the tension
of the valve springs is under suspicion, the valves should be
taken out and the springs tested by compressing the valve
stems together.

34. Excessive Liift of Automatic Inlet Valve. — The

lift of an automatic inlet valve should be proportionate to
the spring tension and to the weight of the valve, so that
the spring will be able to overcome the inertia of the valve,
and close it before the piston has started so far on its com-
pression stroke as to expel any of the mixture through the
open valve.

The symptoms of too great a valve lift are loss of power
and blowing back at high speeds. A valve 2 inches in outer
diameter should not ordinarily lift more than \ inch and a
lift of -^ inch would be excessive for almost any valves
found on high-speed engines. An excessive lift, like a weak

24 TROUBLES AND REMEDIES § 2J

spring, is likely to result in breakage of the valve stems and
keys through unnecessary hammering of the valve when
opening and closing.

35. Broken Inlet-Valve Stem or Key. — Trouble from
a broken inlet- valve stem or key is more likely to occur with
automatic valves than with those mechanically operated.
The result, if the valve opens downwards, is to let it stay
open all the time, causing that cylinder to cease work, while
the sparks from the plug ignite the mixture in the intake
pipe and cause explosions there and in the carbureter. If the
valve, whether automatic or mechanically operated, opens
upwards, it will clatter on its seat and -permit much of the
mixture to be expelled during the first part of the compres-
sion stroke.

36. Weak op Broken Exhaust- Valve Sprinsr* — Owing
to the heat to which it is subjected, the exhaust- valve spring
is more likely to weaken than that of the inlet valve. The
symptoms are loss of power, owing to the valve lingering
open at the end of the exhaust stroke, and clattering when
the valve closes.

37. Broken Exhaust- Valve Stem or Key. — As there
is nothing to prevent the valve from being sucked wide open
on the suction stroke, an accident of this kind will generally
cause that cylinder to go out of action entirely. The clat-
tering, if the engine continues running by virtue of other
cylinders, is likely to be marked.

38. Slipped Valve Cams. — Some cheaply constructed
motors have the valve cams held on the shaft by taper pins
that in time shear partly or wholly through, permitting the
cams to turn on the shaft. The cams may turn a short dis-
tance and then be jammed by fragments of the taper pins.
The symptom indicating trouble due to this cause is partial
or complete loss of power in the cylinder affected, when noth-
ing is wrong with the ignition, valve-spring tension, etc.;
and it will be equally marked at all speeds. If a cam is pinnec

§ 24 TROUBLES AND REMEDIES 25

on its shaft, the proper way to secure it is to add another
pin, or, better, to add a key to take the torsional stress,
and depend on the pin only to keep the cam from slipping
endwise on the shaft.

LUBRICATION TROUBLES

39. liack of Cylinder Oil.— The symptoms of lack of
cylinder oil are manifested in a sudden laboring of the engine,
a dry or groaning sound, and partial loss of compression, fol-
lowed by probable seizing of the piston. If the piston does
not seize, it and the cylinder walls will at all events be
scored.

Among the causes of lack of cylinder oil are clogging of
lubricator by dirt or waste, obstruction in oil pipes, leaky
check-valves, leaky pump packing, broken oil pipe, oil too
cold to feed, lack of oil in crank-case, etc.

The remedies for trouble from 'this source will become
obvious on inspection. The motor should be stopped and
allowed to cool, and a liberal quantity of oil should be put in
the crank-case before starting again. Squirt a little oil
through the compression relief cocks to insure lubrication of
the pistons, without waiting for oil to reach them from the
regular sources. Remove the obstruction or repair the
break as soon as possible.

40. liBck of Oil In Bearlngfs. — A slightly loose main
or crankpin bearing will sometimes be cut badly as a result
of a temporary stoppage of oil feed, and yet give no notice-
able symptom until the bearing is so badly cut that knock-
ing begins. If a well-fitted bronze-bushed bearing becomes
dry, it is more likely to stop or at least retard the engine. A
babbitted bearing will melt out and let the shaft settle
as far as other supports or bearings will allow. The result
may be a violent pounding, a bent or broken shaft, or cut
bearings generally, according to the particular conditions.
There is no real safeguard against lack of oil in bearings
except in the vigilance of the operator, combined with a sys-
tem of oiling not liable to go wrong. It is not safe to depend

20 TROUBLES AND REMEDIES §24

on detecting a dry bearing by the sense of touch, because
often the metal adjacent to bearings is sufl&cient to carry the
heat away.

Generally, trouble from this cause is due to neglect to
supply oil or to see that the sight feeds are working properly.
It may also be due to a broken pipe, cold oil, etc.

There is no excuse for neglect to clean the oil strainer,
or failure to inspect the oil pipes, unions, etc., or to know when
starting out how much oil is in the crank-case. A badly cut
bearing should be sent to a repair shop, and should be
attended to without delay; but a bearing only slightly cut
may be kept in service by t^ie addition of a small quantity of
flake graphite to the oil. If possible, the shaft should be
taken out and polished with emery cloth and oil, else
bronze from the bearing is likely to cling to it and aggravate
the cutting. A bearing supplied with oil from a well
beneath it, and a chain running over the shaft, may occasion-
ally fail to receive oil owing to the chain catching on some
internal roughness or projection in the oil pocket It is
always safest to keep a more or less regular supply of oil pass-
ing through bearings of this sort when in use, and depend on
the oil well only as an equalizer.

41, Improper Oil In Cylinders. — The trouble symp-
toms produced by the use of oil unsuited for lubricating the
piston are white or yellow smoke in the exhaust, rapid foul-
ing of spark plugs, partial clogging of inlet and exhaust
valves, and rapid accumulation of carbon on the valves in
the combustion chamber and about the piston rings.

To remedy the trouble empty out all the unsuitable oil if
possible, and substitute oil known to be good. Inject kero-
sene freely through the compression relief cocks to loosen the
carbon deposit on the piston rings, and use kerosene to
free the valves if they stick. Drain the crank-case, and,
if possible, open it and clean out any carbon that may have
worked down past the piston and mingled with the oil. Change
all the spark plugs, and clean them when opportunity offers.
Put in plenty of fresh oil before starting, and see that oil is

§ 24 TROUBLES AND REMEDIES 27

supplied to the pistons so that they will not go dry before
oil begins to feed from the cylinder lubricator.

43. Too Much* Oil on Pistons. — Too much oil on the
pistons is indicated by white smoke in the exhaust, fouled
spark plugs and valves, substantially as when inferior oil is
used, though the symptoms will not be so pronounced. An
examination of the combustion chamber through the inlet
valve or spark-plug hole, using a mirror and electric flash-
light if necessary, will show an unnecessary amount of oil
around the top of the piston. With the oil Correctly regu-
lated, it should not accumulate on the piston head in any
great quantity.

Trouble from this source is remedied by drawing off part
or all the oil from the crank-case, if it contains more than is
necessary for running the engine, and reducing the oil feeds
to the cylinders if necessary.

COOLrNG-SYSTEM TROUBIiES

43, Ijack of Water. — Lack of water in the radiator of
the cooling system for automobile engines is indicated by
the rapid emission of steam, if there is sufficient water to
entef the engine jacket; the bottom of radiator being cold;
the overheating and smoking of the engine, follo\ved by
laboring, groaning sounds, owing to the oil being burned
away faster than it is supplied to the pistons; and, if the
engine still continues running, expansion and seizure of the
pistons in the cylinders.

Trouble from lack of water is due to carelessness in not
filling the tank before starting; leakage in radiator or
piping; accidental opening of the drain cock at the lowest
point of the circulation system; breakage of drain cock by
flying stone, etc.

The remedies for such trouble are apparent on inspection.
If the motor becomes overheated so that the water boils
rapidly away, and there is reason to think that the upper
portion of the water-jacket is dry, the motor should be

28 TROUBLES AND REMEDIES §24

allowed to cool before water is added; otherwise, the sud-
den contraction may warp or even crack the cylinders^ or it
may cause the cylinders to contract and seize the pistons.
If the water gives out when at some distance from the near-
est source of supply, the motor may be allowed to cool off
and the car then run with throttle nearly closed, and the
spark advanced as much as it will bear without knocking.
This may be kept up sometimes for ^ mile before it is neces.
sary to stop to cool the motor. The crank-case should be
liberally supplied with oil to prevent the pistons from becom-
ing dry, or, if a sight-feed oil cup is put on the cylinder, it
should be set to feed quite rapidly. The motor should be
stopped at the first sign of distress, as indicated by a groan-
ing sound, turning with difficidty, or knocking caused by
preignition due to hot cylinders.

44, Obstructed Circulation. — ^An obstruction to the
circulation of the cooling water elsewhere than in the radia-
tor will cause the bottom of the radiator to remain cool
while the top is, probably, boiling hot.

Among the causes of obstructed circulation are a broken
pump, broken driving connection to pump, or slipping belt
or friction pulley, if the pump is driven in that manner;
waste or the like lodged in the pump or piping.

The remedies for this trouble will become obvious on
inspection. If the belt or friction pulley has oil on it, gaso-
line may be used to clean the pulley, as well as the fly-
wheel if it drives the pulley.

45. St^le or Sediment In Radiator. — ^The presence of
scale or sediment in the radiator is indicated when the whole
radiator becomes hot or when steam formed in the jacket
forces water out of the upper pipe to the radiator, there
bein^v^ no oil on the inside or dirt on the outside of the
radiator.

Scale will deposit from hard water if the temperature of
tlio water is allowed to approach the boiling point. A simi-
lai scale. alni.>st iirpussiMc lo eliminate, will crv'stallize

§24 TROUBLES AND REMEDIES 29

from caldum-chloride non-freezing mixtures if these are
allowed to become supersaturated.

A radiator badly choked with lime scale is practically
hopeless, although, if it is made entirely of brass and cop-
per, it may sometimes be helped by the use of a dilute solu-
tion of hydrochloric acid in the proportion of about one of
acid to ten of water. This should be left in the radiator
long enough only to loosen the scale, and should then be
drawn off, and the radiator washed out. It is better in
doing this to disconnect the radiator from the engine, in
order to confine the effects of the acid. Another method is
to use washing soda, as explained in Automobile and Marine
Engine Auxiliaries, Ordinary dirt may be cleaned out by a
strong, hot solution of lye, which should be used with care,
as it bums the skin badly. Rainwater should be used wher-
ever possible, and all the water should be strained.

46. Dirty Radiator. — When the whole radiator is hot
and it is impossible to run in low gear without boiling the
water, the circulation being good, it is evident that the
radiator is dirty.

Flying oil about the motor may lodge on the air surfaces
of the radiator tubes, and gather dust, which forms a non-
conducting covering. Oil sometimes gathers on the water
surfaces by gradual escape from the pump bearings, or may
remain after an attempt to substitute refrigerator oil for
water as a cooling medium in freezing weather. The film
of oil, preventing the water from coming in contact with the
metal, acts practically as an insulator.

To remove the oil from the radiator use kerosene, or a
mixture of kerosene and mineral-oil soap. Dissolve the
soap in water and add it to the kerosene, fill up the radiator
with the mixture, and run the car for an hour or more until
the radiator gets well heated. The soap and kerosene will
form an emulsion with the oil, and when the mixture is hot
it may be drawn off and the radiator washed out with cold
water. For the removal of the external oil and dirt, use
gasoline, with a brush or swab.

30 TROUBLES AND REMEDIES §24

A simple trouble, but one likely to be mistaken by the
novice for radiator or circulation trouble, is slipping of the
fan belt. The belt should be tested occasionally, and not
allowed to g^et so loose that the fan pulley can spin inside it
It does not need to be tight.

CARBURETER DISTURBANCES

PROPORTIONIXG OF MIXTUKE

47, Ovenich Mixture. — If a mixture is very rich, that
is, if there is an excessive amount of gasoline in the charge,
the fact will be manifested by black smoke in the exhaust.
If the mixture is not rich enough to produce smoke, it will
still produce an acrid odor in the exhaust, and will cause
overheating of the radiator, unnecessary sooting of the
plugs, accumulation of carbon in the combustion chamber,
and unnecessarily rapid comsumption of gasoline, with
diminished power. An automobile of from 12 to 20 horse-
power, running at an average speed of 20 miles an hour, on
good and fairly level roads, should be able to cover 20 miles
on a consumption of a United States gallon of gasoline. If
it does not do this, the carbureter is incorrectly adjusted or
is inefficient.

The causes of an overrich mixture are: faulty carbureter
adjustment; leaky float; leaky float valves; float too high
on its stem or too heavy; spray nozzle loosened or unscrewed
by vibration; and dirt on the wire-gauze screen over the
mouth of the air-intake pipe.

For float troubles, see Arts. 53 to 55, inclusive. Dirt
over the intake may have gathered gradually or it may have
been splashed on from a muddy road. Its effect is to
increase the suction in the spray chamber and to diminish
the air taken in. If necessary, a shield should be fitted to
prevent mud from reaching the air intake and carbureter.
If the float is in good order, the carbureter will probably
need readjustment.

§ 24 TROUBLES AND REMEDIES 31

48. Flooding: is the most common source of trouble in
marine engines using vaporizers. It is caused by leakage
of gasoline into the vaporizer, from which in a two-cycle
engine it readily runs into the crank-chamber; the resulting
mixture is too rich in gasoline, and, not having sufficient
oxygen, is unexplosive. When trouble from flooding is sus-
pected, turn the engine over two or three times, with the
gasoline valve and the switch closed. If there is an explo-
sion, note the color of the flame at the relief cock, or priming
cup, which should be left open for the purpose. If no explo-
sion occurs, leave the cock or cup open and slowly turn the fly-
wheel to a point just before the exhaust port opens, thus draw-
ing air into the cylinder through the priming cup to dilute
what is thought to be an overrich mixture. Now revolve the
flywheel in the opposite direction rather rapidly until the
spark occurs. If there is no explosion, try again, and
repeat the operation two or three times if necessary. If an
explosion then takes place, it is evident that flooding is
present.

To remedy this in a two-cycle engine, open the draw-off,
or drain cock in the lowest part of the crank-case, and draw
off the contents, taking care, however, to replace with a
fresh supply the lubricating oil thus drawn out. If there is
no draw-off cock, it will be necessary to turn the flywheel
many times to exhaust the excess of gasoline in the crank-
case, leaving the switch closed and the compression relieved
as much as possible. After a while, an explosion should
take place, then another, gradually becoming more frequent,
until finally the engine may run with an explosion at every
other revolution or so. The gasoline valve should be kept
closed until the charges explode regularly and the red
tinge to the flame at the relief cock and smoky exhaust dis-
appear, after which the gasoline may be turned on and regu-
lated at the needle valve in the vaporizer, closing it
slightly at first; and, if the engine slows down somewhat,
open it slightly until it is possible to tell whether it is get-
ting too little or too much gasoline.

In case of flooding in a four-cycle engine using a vapori-

32 TROUBLES AND REMEDIES § U

zer, two or three revolutions of the crank-shaft will usually
dispose of any excess of gasoline, for there cannot be as
large an amount in the exhaust piping of a four-cycle engine
as could accumulate in the crank-case of a two-cycle engine.
Trouble from flooding in a two-cycle engine is the first
thing to be suspected when an engine of that type refuses to
start readily.

If the cause of a failure to start is found to be an insuf-
ficient supply of gasoline, due to dirt in the needle valve, or
to a small amount of water in the gasoline piping, lift the
valve in the vaporizer from its seat and let a little gasoline
run through to clear the obstruction or get a drop or two
of the water out, being sure to catch the drip for exami-
nation. If there is any water it will show in globular form
at the bottom of the vessel. In case water is found, the
pipe must be disconnected and drained, and any water in
the tank must, if possible, be removed, for a single drop of
water will completely close the aperture in the seat of a
needle valve.

49. Weak Mixture. — Among the symptoms produced
by a weak mixture are insufficient power, although the
explosions are regular; a tendency to preignite or to bum
very rapidly if there is the slightest carbon deposit; the
engine sometimes will miss every other explosion. There
is likely also to be difficulty in starting the engine. It is
not always easy to distinguish between lack of power due to
an overrich mixture and that due to a weak mixture, but
the tendency of the former is to produce black smoke and of
the latter to preignite and miss explosions. Some experi-
menting with the carbureter adjustment will often be neces-
s«'iry to settle the point.

Nearly all the causes named in Art. 47 will make a mix-
ture richer at some speeds than at others, and if the carbu-
reter has been readjusted, for example, in the attempt to
correct trouble due in reality to a heavy float, the result will
be to make the mixture faulty again at certain other speeds.
Special causes of weak mixture are dirt or waste in the

§ 24 TROUBLES AND REMEDIES 33

gasoline pipe or strainer; stale gasoline; carbureter too cold
to vaporize ; dirt in the spray nozzle ; float too light or too
low on its stem.

For float-trouble remedies see Arts. 53 to 55, inclusive.
Experimenting with the carbureter adjustment should be
very cautiously done, with the original setting or adjust-
ment marked so that it can be restored if necessary. The
carbureter should then be adjusted slightly in one direction
or the other, and the effect noted before further change is
made. Very often a combination of adjustments will be
necessary, but it is best to make them one at a time. If a
radical change is made, it may be very difficult to start the
motor at all, and this would leave the experimenter com-
pletely in the dark as to what was required.

BIBT IN CARBURETER AXD GASOL.rNE PIPING

50. Dirt In Carbureter. — If there is dirt in the float
valve, it will prevent the latter from closing and will cause the
carbureter to flood. This will produce an overrich mixture,
especially at low speeds, and is highly dangerous on account
of the liability to fire. If the dirt is in the spray nozzle, it
will produce a weak mixture. If the dirt has been splashed
into the air intake, it will produce an overrich mixture,
especially at high speeds.

The remedies for trouble due to dirt in the carbureter
will become obvious when the nature of the trouble is located.
A carbureter that has previously worked well and that sud-
denly begins to leak has in all probability dirt in the float
valve. A carbureter that suddenly gives a very weak mix-
ture has dirt probably in the gasoline pipe, strainer, or spray
nozzle.

51. Dirt or Waste In Gasoline Pipe. — It is a common
practice to carry a bunch of waste under the seat of an auto-
mobile. Usually, the gasoline tank is near the seat, and in
time a sufficient quantity of fluff from the waste may enter
through the vent-hole in the feed- cap of the tank to create

U TROUBLES AND REMEDIES § U

an appreciable obstruction in the gasoline pipe. Even if
this does not happen, dirt or other obstructions sometimes
accumulate, especially if the gasoline has not been properly
strained. The symptom is a sudden or gradual weakness of
the mixture, necessitating readjustment of the carbureter in
order to keep the engine running. The most probable
place of lodgment for obstructions of this sort is in the gaso-
line pipe where the latter connects to the carbureter, or at
the strainer, through which the gasoline generally passes just
before it enters the float chamber. Disconnecting the gaso-
line pipe or the union exposing this strainer will generally
disclose the obstruction. Sometimes it may be necessary to
disconnect the gasoline pipe at both ends, and blow it out
with the tire pump. This is necessary only when the pipe
has been disconnected near the carbureter and" gasoline does
not flow freely from it when turned on at the tank.

FLOAT TROITBUES

53, licaky Float Valve. — With a leaky float, the car-
bureter drips when the main gasoline valve is opened. The
leakage is not stopjDed when the top of the float chamber is
opened and the needle valve pressed down with the finger,
or when the mixing chamber is opened and the spray nozzle
covered with the finger.

To remedy the trouble grind in the valve with pumice or
fine sandstone.

53, Float Too nigrh. — By the expression yfo^/ too high
is meant that the float is set too high on its stem so that it is
not lifted by the gasoline sufficiently to close the float valve
before gasoline escapes from the spray nozzle.

When this trouble is present, the carbureterdrips when the
main gasoline valve is opened; but the float valve is soon
closed by the float if the spray orifice is covered by the finger.
The float valve closes tight when manipulated by the fingers,
or wlien the float is lifted by a pair of bent wires. When
the trouble is due to a hii>h float, it will be foimd that the

§ 24 TROUBLES AND REMEDIES 35

float itself is empty, and, if of cork, that it is not gasoline-
soaked.

Unless the float is adjustable on its stem, the easiest reme-
dy for this trouble is to bend the levers by which the float
acts on the float valve. If this cannot be done, shift the
float ^ inch lower on the stem by the use of a soldering
iron.

54. Float Too Heavy. — The same symptoms are pres-
ent when the float is too heavy as when the float is too high,
but they are caused generally by a leak in the float or by its
being gasoline-soaked.

If the float is hollow, it will sometimes be found that there
is present in it a minute leak due generally to some oversight
in soldering. If the float is taken out and shaken with
the hand, the presence of the gasoline inside of it will at
once be apparent. The float should be immersed in warm
water until all the gasoline in it is slowly boiled away and its
vapor has been expelled through the aperture in the float.
By holding the float under water, the escape of bubbles will
indicate this aperture. Care should be taken that the vapor
escaping from the float does not cause fire. When the leak
has been located it should be marked with a pencil, and after
the float has become cold the leak may be closed with a
minute drop of solder. If the float is of cork, it may be satu-
rated with gasoline. It should be taken out, allowed to
dry slowly, and given a coat of shellac, care being taken that
the shellac enters all the holes on the surface.

55. Float Too lAglit or Adjusted Too IjO-w. — By the

expressions ^oat too light or adjusted too low is meant that
the float is lifted by the gasoline in the float chamber when
the gasoline level is still some distance below the orifice of
the spray nozzle.

Among the symptoms produced by a light float or a low
adjustment are a weak mixture at slow speed, and, probably,
difficulty in starting the engine, owing to the fact that con-
siderable suction is required to lift the gasoline to the mouth of
the spray nozzle. The height of the gasoline in the spray

36 TROUBLES AND REMEDIES § 24

nozzle can generally be determined, with the aid of an electric
flashlight, by a little experimenting with the float, pushing
the latter down for an instant after it has closed the valve.

To remedy the trouble, the float must be weighted slightly,
so that t6e gasoline will rise higher before the float closes its
valve. The weight may take the form of a few drops of
solder carefully distributed over the float so as not to over-
balance it on one side; or, if this is not sufficient, a ring
of sheet brass may be soldered to the top of the float.

FUEL TROUBLiES

56. Stale Gasoline. — If an automobile has been left
standing for some time unused, more or less of the gasoline
in the tank will evaporate, and it may get too stale to give a
correct mixture without readjustment of the carbureter.
The usual symptoms are difficulty in starting the engine,
and insufficient power owing to a weak mixture. The best
remedy is simply to fill up the tank, when the mixture of
old and fresh liquid will probably work satisfactorily. It
may be necessary, however, to readjust the carbureter or to
throw away the stale fuel. It frequently happens when
touring that the gasoline procured at country stores is very
stale, and it is safest to test it with a hydrometer before
accepting it. The user should know for what density his
carbureter is adjusted, and should not depart from this
more than is necessary. Ordinary stove gasoline is sup-
posed to test 74° or 76° Baum6, but is frequently found
testing as low as 68° or 66°.

57, Water In Gasoline. — Water may be found in gaso-
line taken from a barrel standing out of doors. The water,
being heavier than the gasoline, will always settle to the
bottom, and by close observation it may be seen before it is
poured into the tank. If the gasoline is strained through a
piece of chamois skin or several layers of cheese cloth, or
even through very fine brass-wire gauze, the strainer will hold
the water while permitting the gasoline to pass through.

§ U TROUBLES AND REMEDIES 87

The user should make it an invariable rule to strain his g-aso-
line in this manner.

The symptom of water in the gasoline will be immediate
stoppage of the engine when the water reaches the spray
nozzle, in spite of the fact that the timer, coils, battery,
spark plugs, etc. , are in perfect order, and the gasoline tank
is known not to be empty. The only remedy is to unscrew
the wash-out plug at the bottom of the carbureter, and let
the water and gasoline run out until it is certain that all the
water has escaped. Sometimes it may be necessary to dis-
connect the gasoline pipe entirely and blow it out in order
to expel the last drop of water. It is well also to look into
the tank with an electric flashlight and see if any drops of
water can be discovered on the bottom. If so, it may be
well to drain the entire tank. Extreme care should be taken
to avoid fire while gasoline is being run off.

58. In stationary practice, besides using gasoline of
proper quality, it is of course supposed that the storage tank
contains a sufficient quantity of fuel to run the engine. This
appears to be a superfluous precaution, nevertheless it has
frequently happened that an expert has been sent several
hundred miles, on complaint from the purchaser of an
engine that he was unable to start it, only to find that there
was no gasoline in the tank. In other cases it was discov-
ered that, instead of gasoline, almost pure water was
pumped to the engine. The explanation was that fuel pur-
chased from a local dealer contained a considerable quantity
of water, which of course settled to the bottom of the tank,
and accumulated gradually until with the tank about one-
quarter filled, nothing but water would be delivered to the
engine. To avoid this, the contents of the tank should be
examined at regfular intervals or when the supply is low,
and the tank drained whenever there is any doubt about the
quality of the liquid that settles in the lower portions.

16»— 26

38 TROUBLES AND REMEDIES §24

BACKFnUNG

59. The cause of back firing in stationary engines is in
most cases due to the delayed combustion of a weak mixture
containing an insufficient amount of fuel. The result of
such a mixture is a weak explosion and slow burning, so
that, during the entire exhaust stroke and even at the begin-
ning of the suction stroke, there is a flame in the combus-
tion chamber. The fresh charge will therefore be ignited
by the flame of the delayed combustion of the previous
charge ; and, as the inlet valve is open at that time toward
the air-supply pipe or passage, a loud report will be heard in
the air vessel or in the space under the engine bed whence
the air is taken. The remedy for this condition is to
increase the fuel supply until the explosions become of nor-
mal strength and the back firing ceases.

Another cause of back firing may be the presence of an
incandescent body in the combustion chamber, such as a
sharp point or edge of metal, a projecting piece of asbestos
packing, soot, or carbonized oil, and similar impurities
accumulating in the cylinder. To stop back firing from
these causes, any projections of metal or other material
should be removed with a suitable tool, and the walls of the
combustion chamber made as smooth as possible, or the
cylinder should be cleared of any deposit of soot or carbon-
ized oil that may have gathered there.

Failure of the igniter to fire all charges admitted to the
cylinder, or improper composition of the mixture resulting
in the same way, will be indicated by heavy reports at the
end of the exhaust pipe. One or more charges may in this
manner be forced through the cylinder into the exhaust
pipe, and the first hot exhaust resulting from the combus-
tion of a charge will fire the mixture that has accumulated
in the pipe and the explosion wU be accompanied by a
report similar to that of the firing of a heavy cannon.

60, On account of the shorter time between the opening
of the exhaust port and the admission of the new charge in

§ 24 TROUBLES AND REMEDIES 30

a two-cycle engine, there is much greater liability to back
firing in an engine of that type than in a four-cycle engine.
In a four-cycle engine back firing will occur only when the inlet
valve is off its seat ; hence, in marine j^ractice, back firing is
more of an element of danger in four-cycle than in two-cycle
engines. If there is no check-valve in the carbureter or
vaporizer, and there is no direct opening to the atmosphere,
the column of flame that would be blown into a boat
through a carbureter or auxiliary air supply on account of
back firing would be particularly dangerous because accumu-
lations of gasoline vapor, especially in cabin boats, might
thereby become ignited.

To be absolutely safe, a marine four-cycle engine having
a float-feed carbureter not supplied with a check-valve
should take its supply of air from some point outside of the
cabin or from the top of the engine, rather than from a
point near the base. As the use of a check- valve in the
carbureter would materially reduce the efficiency of the
engine, it is rarely used. If a float-feed carbureter is used,
and indications point to imperfect carburization, the carbu-
reter should be examined carefully. If the float leaks, so
that the height of gasoline is constantly above the desired
level, or if the float does not cut off the supply where it
should, it will be necessary to take the carbureter apart to
ascertain the trouble, which may be due to a stopped-up
needle valve or nozzle.

61. Explosions in the muffler and exhaust piping are
usually caused by the ignition of the gas accumulating from
missed explosions due to weak mixtures or faulty ignition.
They are not usually dangerous unless the muffler is large and
is weakened by rusting inside or out, as from salt water
passing through it or from damp salt air, against which it
seems almost impossible to protect it in a boat.

•

62. Explosions in the carbureter are sometimes caused
by the inlet valve sticking open and permitting the flame to
communicate from the spark. More often it is due to
improper mixture, which bums so slowly that flame lingers

40 TROUBLES AND REMEDIES § 24

in the cylinder even after the exhaust stroke is completed
and the inlet valve begins to open. Either a weak or a rich
mixture will produce this result, though not alwajrs both in
the same engine. Carbureter explosions are often attributed
to the exhaust valve closing after the inlet valve opens, or
to simple leakage of the inlet valve; but these are seldom
the real causes.

IGNinOX TROUBIiES

PREIGKTTION

63. Deflnltlon. — Premature ignition, or preignition,
while somewhat similar to back firing in its nature and
origin, manifests itself in a diflPerent way and has a different
effect on the action of the engine. Premature ignition, as
usually understood, is the firing of the partly compressed
mixture before the time fixed by the igniting mechanism.
Its causes are similar to those that result in back firing, the
effect being different in that the charge is ignited later
than when back firing takes place, but before the end of the
compression stroke. Preignition will cause the engine to
lose power on account of the maximum pressure being
exerted on the crank before it reaches the inner dead center
and thus ha\'ing a tendency to turn it in the >\Tong direction,
airainst the momentum of the flvwheels.

64, Causes of Preigrnition. — Besides the causes cited
in connection with back firing, preignition may be due to
any one of the following defects: Insufi&cient cooling of the
cylinder, due either to shortage of cooling water or to the
fact that portions of the water-jacket become filled vnih
lime deposits or impurities contained in the water, thus
interfering with proper circulation; compression too high
for ilie *:Tade of fuel used ; imp)erfections in the surfaces oi
I ho piston end or valve heads exposed to the combustion,
such as s.ind holes or similar caWlies in which a small por-
tivMi o( the Iniruing- charge may be confined; electrodes or

§ U • TROUBLES AND REMEDIES 41

other parts of the engine exposed to the burning charge too
light; or the piston head or exhaust- valve poppet insuffi-
ciently cooled and becoming red hot while the engine is run-
ning under a fairly heavy load.

65. Premature ignition manifests itself by a pounding

in the cylinder, and, if permitted to continue, a drop in

speed, finally resulting in the stopping of the engine. It

vrill also put an excessive amount of pressure on the bearings,

especially the connecting-rod brasses, and cause them to run

liot even when properly lubricated. After a shut-down due

to premature ignition and a short period during which the

engine is idle, allowing the overheated parts to cool oflF, it

is possible to start again without difficulty and run smoothly

until the conditions of load will cause a repetition of the

trouble.

66. The remedies to be applied, according to the source
of the difficulty, are as follows : Increase the water supply until
the cooling water leaves the cylinder at a reasonable tem-
perature, which may vary with the fuel used, but which
should never be over 180° F. Clean the water space and
ports of any dirt or deposit so as to insure free circulation
of the cooling water. Reduce the compression by partly
throttling the air and fuel supply. Plug any sandholes or
blowholes in the piston or valve heads, and make these sur-
faces perfectly smooth. Replace electrodes or other light
parts with more substantial ones, capable of absorbing and
carrying oflF the heat without becoming red hot. If neces-
sary, arrange for cooling the piston by blowing air into the
open end of the cylinder.

If the head of the exhaust valve becomes too hot, it is a
sign that it is not heavy enough, and it should be replaced
by one with a head of sufficient thickness to carry off
through the valve stem the heat imparted to it by the com-
bustion. If a small particle of dirt lodges in a remote por-
tion of the combustion chamber, the richer part of the
charge may not reach it until the piston has traveled over a
considerable portion of the compression stroke, and the

42 TROUBLES AND REMEDIES §24

resulting self-igrnition may properly be called preignition.
It is advisable, therefore, to examine thoroughly every part
of the combustion chamber and remove any dirt that may
have lodged there.

67, Preignition in automobile engines is indicated by
early ignition with a retarded spark. Usually, the engine
will continue running for several seconds after the switch
has been opened. The knock due to preignition has a sharp,
metallic ring, easily distinguishable from other knocks in
the engine. Even if ignition is not actually started by hot
carbon or other cause, the first increase in pressure after the
spark occurs may produce spontaneous ignition of the mix-
ture near the heated object, so that the charge bums from
two or more points at once, thus spreading the flame far
more rapidly than usual.

If the engine has two or more cylinders, and only some of
them incline to preignition, the result is that it is impossible
to time the ignition correctly for all cylinders. The cylin-
ders having a tendency to preignition must receive a late
spark to prevent combustion from being completed too
early, while the other cylinders will require an early spark.
It follows from this that it is impossible to get the engine to
develop its full torque, or turning moment, unless it is run-
ning so fast that the tendency to preignition may be neglect-
ed. As the eflPect of preignition is to cause combustion to
be completed before expansion has begun, it is dangerous to
run the engine slowly, and this is true even if only one
cylinder is preigniting. If the engine is running at good
speed, with an early spark, the symptoms will be those of
rapid combustion in the cylinders aflFectefl; namely, a hard-'
ness in the sound of the explosion, without actual knocking,
while in the other cylinders, if any, the explosion will be
soft. As the speed of the engine is reduced, and the spark
retarded to suit, the hard sound of the explosions gives
place to unmistakable knocking. A good test for preignition
due to carbon is to start the motor with everything cold, and
run the car smartly up the nearest hill before the water in the

§ 24 TROUBLES AND REMgDIES 43

radiator has had time to get hot. The bing! bing! bingf
then is a sure sign. If the carbon deposit is very great, the
motor may knock when gearing up, if this is done quickly
with the motor running rather slowly.

In ^ automobile as in stationary engines, preignition is
"brought about by incandescent carbon deposits in the com-
T>ustion chamber, on piston head, or on valves, or by bits of
loose carbon left after scraping out, etc. It is sometimes
due to small, accidental projections on the inner wall of the
combustion chamber or head, due to defects in casting. If
these are located in the path of the hot gases, it will take
very little carbon deposit on them to overheat. Preignition
is also caused by lack of water, resulting in general over-
heating.

It must not be supposed that all carbon deposits are due
to neglect. Even the most scrupulous regulation of the
best possible oil, and even the most efficient carbureter, will
not wholly prevent a gradual accumulation of carbon, but it
ought not to become troublesome in less than a season or
two. A high-compression engine will, other things being
equal, preignite sooner than one with low compression.

The only remedy for carbon deposit that amounts to any-
thing is to scrape it out. To do this it may be necessary to
take off the cylinders, but it may also be done in some
cases by the use of special forms of scrapers that will reach
into the combustion chamber through the inlet-valve or
spark-plug hole.

If it is impracticable to scrape the cylinders at once, the
trouble may be evaded after a fashion by running throttled
and by running on a lower gear at the first symptoms of a
pound. Increasing 'the richness of the mixture will also
prevent pounding by making the charges bum more slowly,
but this brings its penalty by adding to the carbon already
present. If this trouble is due to chance projections in the
combustion chamber, these may generally be disclosed by
an electric lamp and mirror and when the cylinders are
taken off, the projections can be cut away with a cold
chiaeL

ii TROUBLES AND REMEDIES §24

BATTEBT TBOlTBIiBS

68. Weak Battery. — Missed explosions may result from
a weak battery. An open-air test of the spark, by discon-
necting a cable from one of the plugs or laying a screwdriver
on the plug binding post, will show a weak spark when the
battery is weak. It is sometimes difficult to determine
whether the explosions are missed because the battery is
weak or because of a loose connection or broken wire some-
where in the ignition circuits. The only reliable way to
determine this point, unless one has a fresh set of cells in
reserve, is to carry a battery tester and test the cells as soon as
skipping occurs. The battery strength required will depend
on the character of the coil, but it is not often that a dry cell
showing less than 5 amperes on short circuit is worth retaining.

If both sets of dry batteries are so far exhausted that
neither will work the coil, the two may be coupled in series,
which will generally make it possible to run the car for some
miles farther. When home is reached the batteries should
be recharged or replaced.

A wet- or a dry-cell battery for supplying the current will
be exhausted after a certain period of time, and, if handled
carelessly, its life may fall far below what may reasonably be
expected. If a wet battery becomes exhausted through
long service or accidental short circuit in its parts or connec-
tions, the contents of the jars must be emptied and the
charge renewed. The manufacturer or dealer in elec-
trical supplies furnishes full printed instructions with every
set of renewals for batteries. It is generally false economy to
try to use part of the old charge. In almost every case it is
far better to throw away all of the original zincs, oxide
plates, and solution, rather than to try to rejuvenate the cell
by adding to or replacing part of its contents.

69. Current JLeakagre. — Sufficient leakage of current
to make trouble — but not enough to be observed without
testing with a magneto — may be due to moisture in the mica
insulation of the insulated electrode or to abridge of carbon.

§ 24 TROUBLES AND REMEDIES 45

When it is suspected that the trouble is due to either of these
causes, it is a good plan to dry out the insulation thoroughly
and clean the lower end with a brush or piece of waste and a
little gasoline.

These troubles are more liable to occur when the batteries
have become weak from use, or so far exhausted that they
will not give sufficient cturent for ignition.

70. Testing Batteries. — By using a small electrical
buzzer or bell each cell may be tested separately, and by
the tone or sound it can readily be observed whether or not
the battery needs renewing, as is often the case. A small
pocket ammeter or voltmeter is very convenient for the pur-
pose of testing batteries, but each cell should be tested sepa-
rately, as the pocket apparatus will rarely stand the voltage
or amperage of more than one cell. Occasionally the buzzer,
bell, or voltmeter will show one of the cells of the batter)'
exhausted or dead, and on its removal the battery will show
sufficient strength for ignition purposes.

71. Beserve Battery Poiver. — While four or five dry
cells, when new, will furnish sufficient current for ignition,
it is customary to install six or even eight cells, so that, when
they become partially exhausted, or it becomes necessary to
remove one or two from the circuit, there will be a sufficient
number left to supply the necessary current. It is, how-
ever, never safe to depend on a single battery. A reserve
set of dry cells, carefully wired up, should always be carried
in a dry box, for frequently when used in a boat the bottoms
of the dry cells may become damp or the switch is liable to
be left closed, with the electrodes in contact, with the result
that, through the short circuit thereby produced, the bat-
tery will be exhausted and ruined in a very short time.

SPARK-PLUG DISORDERS

73. Broken Spark-Plugr Porcelain. — The breaking
of a spark-plug porcelain usually results in complete failure
to ignite the charge in that particular cylinder, ov

46 TROUBLES AND REMEDIES § 24

the secondary current shortingr, that is, short-circuiting,
through the break. The outer end of the porcelain will
generally be loose when tried by the fingers.

The usual cause of breaking is screwing the bushing down
too tight. If the asbestos packing is of uneven thickness, it
may be necessary to screw the bushing quite tight to prevent
leakage. Overheating and splashing of water on a hot porce-
lain will also cause breaking. Remedies for such trouble are
found in using new asbestos packing and in providing pro —
tection from water, etc.

73. Soot on Spark-PIufiT Porcelain. — Soot on th^
spark-plug porcelain will cause misfiring, or total failure to
ignite, when the battery is of proper strength and the
vibrators on the coils are working properly. If the engine
has more than one cylinder, probably one or more will be
found to be working properly, and the one with the defective
spark plug may be located by holding down one coil vibrator
after another, thus stopping explosions in each cylinder in
turn, until the vibrator feeding the inactive cylinder is
reached. By listening carefully to the exhaust, when it is
known that one cylinder is misfiring, it will be observed
that, when the vibrator of an active cylinder is depressed, it
will cause a noticeable break in the cycle of explosions
When the vibrator of an inactive cylinder is depressed, no
such break will be noticed. It is, of course, necessary to
know which cylinder is fed by each vibrator. A spark plug
may be sooted to the extent of short-circuiting when in the
cylinder, and yet spark properly in the open air, as the elec-
trical resistance of air increases greatly when the air is com-
pressed. If a plug is slightly sooted, and there is uncertainty
as to whether the trouble is due to the soot or to something else,
insert a fresh plug, substituting one from another cylinder, if
there are no spare plugs at hand, and note the result. A primary
sparker coated with soot will act nearly the same as a sooted
plug; the extra current producing the spark will leak away
lo a considerable extent through the carbon instead of pro-
ducing an effective spark.

§ 24 TROUBLES AND REMEDIES 47

The causes of sooting are too much lubricating oil, inferior
oil, or a too-rich mixture. The overrich mixture will
deposit pure black soot, whereas an excessive quantity of
lubricating oil will produce a rusty-brown deposit. Inferior
oil may produce almost any sort of a deposit, according to its
quality. A great excess of either good or bad oil will not
burn completely before it reaches the plug, and will deposit
on the latter a greasy mixture of carbon, tar, and oil. An
engine receiving oil in such quantities as this will foul the
plugs within a mile or two, and energetic measures must be
taken to get rid of the surplus oil.

If the sooting is not excessive, and if the cause is removed,
the plug may be kept in action without cleaning by the use
of an auxiliary spark-gap device, which may be connected
to the binding post of the plug. The soot will then be
gradually burned off.

74. Jjealcy Spark Pluitc. — If the leak is between the
plug shell and the cylinder, it will be denoted by the hiss of
escaping gas on the compression and power strokes. The
plug may be screwed tighter or a new gasket used. If the
leak is through or past the packing inside the plug, the same
hiss will be heard, and in addition the outer end of the ])c)rcc-
lain will show traces of soot after the gases have been leaking
for some time. If the bushing of the plug has been screwed
as tight as is prudent, with regard to the safety of the porce-
lain, it will be necessary to repack the phig. A plug allowed
to leak to any noticeable extent will overheat, cracking the
porcelain or burning the screw threads.

MAK£-AXD-BR£AJC IGNITKIl TIIO|T|triKlB|

75. Poor Contacts. — In order to obtain a spark of mtf-
ficient size in the combustion chambers of engin(»H cfpilppod
with the make-and-break system of igniticMi, it is nrccssiiry
that a good contact l)e made between tlie tw«» elcM'tHKlrs nf
the igniter plug Ixifore ihcy separate. Th«* cnrnMH pnHsrM
through the bearing of the movable eleelrode, and, if thn

48 TROUBLES AND REMEDIES § 24

contact between the bearing and the stem of the electrode
is poor, only a weak current can find its way to the point of
contact, resulting in a feeble spark that may be too weak to
fire the compressed mixture. Poor contact of the electrode
may be caused by an inferior quality of lubricating oil form-
ing a thin layer of carbon (which is a poor conductor) on the
stem, or it may be due to wear of the bearing and a loose fit
of the stem. To prevent wear on the stem and bearing it is
important that the seat of the electrode be kept tight, so as
to prevent the heat of the burning charge from reaching
the stem and to keep it as cool as possible. This will aid
in keepingthe stem well lubricated, as the oil cannot be burned
and form the objectionable carbon deposit. At the same
time, the electrode will move easily without sticking, which
is essential to a prompt separation of the two contact points.

76, Short Circuits, — A ground or short circuit of
the current is often responsible for difi&culties or failures of
the igniter. This may be caused by carbonized oil on the
exposed surface of the insulators, or by dampness between
the mica washers if these are used for insulation. By pla-
cing the igniter plug in a warm place and drying it thor-
oughly, a short circuit of this kind can often be remedied.

77. Slioit-Tline Contact. — The length of time during
which the electrode points are in contact has a decided
effect on tlie size of the spark. To test whether the contact
is of sufficient duration, hold the two points together by
exerting pressure by hand on the movable electrode. If
this is found to cure the trouble, it is a sure indication that
the contact is too short, and the parts that make the contact
must then be adjusted so as to prolong the time of contact.
This is accomplished in some igniters by increasing the ten-
sion of the igniter contact spring, while in others the
adjustment is made by changing the relative positions of the
interrupter lever of the movable electrode and the blade of
the igniter lever that operates it and presses it against the
fixed electrode.

§ 24 TROUBLES AND REMEDIES 49

78. Dirty Contact Points. — The contact points must
be kept free from rust or moisture, both of which will inter-
fere with the making of a bright spark. An occasional
cleaning of the points by the use of emery cloth is advisa-
ble. Moisture on the electrode may be caused by condensa-
tion of the exhaust gases if the electrodes are very cold,
which is likely to be the case in freezing weather before
starting. The remedy is to heat the igniter plug thoroughly
l)ef ore attempting to start the engine. If moisture deposited
on the electrodes is the result of a leaky packing or gas-
Icet, or of a defect in the cylinder, allowing water to enter
the combustion chamber from the surrounding jacket space,
it is possible to overcome this temporarily by wiping the
interior of the combustion chamber dry with cotton waste or
similar material. In this way the water may be kept away
from the igniter long enough to get the engine started; but
the real source of the trouble should be remedied at the
earliest opportunity.

COIL DERAXGEMENT8

79. Vibrator Out of Adjustment. — If the vibrator
sticks, the symptoms will be erratic firing; few or no explo-
sions will be missedi but the impulses will sometimes be very
weak because the sticking causes a very late spark. Too
light a pressure of the contact screw will cause the engine
to run weak and fitfully; too much pressure will exhaust
the battery rapidly. Either condition will manifest itself to
the practiced ear by the sound of the vibrator. Poor firing
may be caused also by pitting of the contact points. This
may be remedied by filing the contact points, which should
bear squarely against each other, and readjusting the spring
and contact screw.

80. Defective Condenser. — A condenser short-cir-
cuited or having one of the connections broken will show it
by sparking at the trembler and timer contacts, and by rapid
burning of the metal where the spark occurs. The only
remedy is to send the coil to the factory for repairs.

50 TROUBLES AND REMEDIES § 24

81. Short-circuited Coll. — A spark coil may short
circuit from breakdown of the insulation in either the pri-
mary or secondary winding. The sytnptom is a poor spark
or none at all, and refusal of the vibrator to work, even
with a good battery. The only remedy is to send the coil to
the factory for repairs. The spark coil must be kept in a-
thoroughly dry place, as moisture will surely cause trouble^
and will interfere with the current passing through the coil_
to the engine. If the spark coil is found to be moist, it cam^
generally be put in serviceable condition by drying it in aim^
oven.

TVIRING TROUBLES

83. Break In Primary Circuit, — The symptoms pro-
duced by a break in the primary circuit, which includes all
wiring except from the coil to the plug, or from a secondary
distributor to the plugs, are intermittent or complete failure
to spark, according to whether the connection is intermit-
tently restored by vibration or is wholly broken, and failure
of the vibrators to work.

The almost invariable cause of breaks in the primary cir-
cuit is vibration, which will loosen nuts on binding posts and
break wires in places sometimes quite unexpected.

The first step to be taken in remedjring the trouble is to
test every binding post, usually by shaking the wires with
the fingers. If this does not disclose the trouble, hunt for a
break in the wiring. It will generally be found close to a
binding post, switch terminal, or other connection, where
the bending due to vibration is most severe. As a last
resort, close the switch, open the compression relief cocks,
retard the spark, and turn the crank so as to make contact
at the timer; then with a length of spare wire shunt suc-
cessively each wire in the primary circuit by touching the
ends of the spare wire to the ends of the regular wire until
you have found the one with the break. The spare wire
thus bridges the break in the regular wire and causes the
igniter to operate. Then hunt down the break in that par-
ticular wire, or take it out and put in a new one. If the

§ 24 TROUBLES AND REMEDIES 51

wire has a soldered joint, it will be brittle at that joint and
may have broken ; or, it may have been fastened in such a
manner as to strain it; or a badly made and twisted joint
may have worked loose. Note that the break may be
between the timer and the coil, in which case it will aflFect
one coil only. A wire is quite likely to break inside its
insulation, or just at the point where the insulation
has been stripped oflF. A troublesome kind of break is
that which is opened only by the vibration of running, and
is closed by the elasticity of the wire or insulation, or by the
weight of the battery cells or other connected members,
when the car is stopped. A great deal of patience is some-
times needed to trace a break of this sort.

83. Short Circuit or Ground In Primary. — A short
circuit or ground in the primary conductor is not a common
trouble, and it can be avoided by the most ordinary care in
insulating the primary. The symptoms are much like those
due to a broken wire, but an ammeter test close to the bat-
tery will show that current is flowing. It is most likely to
occur by the chafing through of the insulation of poorly sup-
ported wires, or by neglect to insulate properly some home-
made attachment in the circuit. It may be due to contact
of the dry primary cells or bolts passing through the bat-
tery box. A little patience is all that is needed to locate
the trouble.

84. Broken Secondary Cable. — As the secondary
cables are short and thick, a break in them is an unusual
fault. If the break is not too great, the current will jump
it, and the sparking there will at once disclose the trouble.

85. Grounded Secondary Cable. — A grounded sec-
ondary cable, which is indicated by failure to spark when
the vibrator is working, is generally due to the chafing
through of insulation on a badly supported cable. Some-
times it is due to rotting of rubber insulation by heat and
oil. If the secondary cable has been spliced and taped, the
current will go thr' unless the cable is well out

52 ' TROUBLES AND REMEDIES § 24

of the way of grounded metal work near the splice. Such a
cable may give a spark at the plug as well as at the ground,
which will soon exhaust the battery.

The roadside remedy for a grounded secondary wire is to
tie the cable clear of the metal work. The permanent reme-
dy is to put in a fresh cable, adequately protected by fiber
tubes or other insulating supports. A cable with a var-
nished exterior is the best, as it resists oil. A rubber-cov-
ered cable exposed to oil may be protected by a coat of
shellac or a layer or two of tape.

86, lioose Electrical Connections. — To obviate fail-
ure to start because of loose or defective electrical connec-
tions, the ignition mechanism should be tested carefully.
With the make-and-break system of ignition this is done by
disconnecting the wire from the binding post or nut of the
insulated electrode while the electrodes are in contact, and
then snapping the end of the wire across the binding nut of
the insulated electrode. If a good fat spark is produced
when the wire slips off the nut, thus breaking the circuit, it
is evident that the circuit is not defective beyond the igni-
ter and that the contact between the electrodes is good.

If, with the wire connected to the insulated electrode and
with the igniter contact points separated, a screwdriver
were placed so as to make contact with the binding nut of
the insulated electrode and with a capscrew, studbolt, or some
bright part of the engine, the production of a spark when the
contact between the screwdriver and the nut of the insulated
electrode is broken would indicate that no short circuit
exists in the igniter. If, however, no spark should be pro-
duced on breaking contact with the screwdriver, it would
indicate the existence of a short circuit that should be found
and eliminated. Should a spark be produced on breaking
contact with the screwdriver when the two electrodes are in
contact, it would be evidence of poor contact between the
points. No spark will appear on breaking the circuit when
the contact between the points is good.

The break of a wire inside the insulation, while not of

§ 24 TROUBLES AND REMEDIES 53

frequent occurrence, is harder to locate than a loose electrical
connection. In cases where it appears impossible to find
the trouble, the existence of the broken wire may be deter-
mined by running a temporary wire from the coil to the
engine, spark coil, switch or battery, as the broken wire
may be so situated as to show occasionally either an open or
a closed circuit.

A loose rocker-arm fastened to the movable electrode will
sometimes give considerable trouble that will be found dif-
ficult to locate. A very little lost motion where the shaft is
small is increased rapidly; and, as soon as the shaft becomes
the least bit loose, the pounding to which it is subjected will
caUse it to loosen very quickly.

Switches should have good, clean contact points, otherwise
leaks will affect both systems of ignition.

TIMER TROUBIiES

87. Timer Contacts Rougrhened by Sparkingr*

Trouble due to roughening of the timer contacts by spark-
ing is likely to occur in any timer in which the contact
segments are inserted flush with the insulator barrel or
internal ring, instead of projecting therefrom.

The symptom produced by roughened contacts is irregular
firing, due to jumping of the contact roller or fingers. This
is not noticeable at low speeds, but becomes marked as the
speed increases. The remedy is to true the insulator ring
and segments in a lathe, and, if necessary, put in a new
roller or contact fingers.

88. Wabbling Timer. — Some timers have their sta-
tionary portion supported on the shaft by a very short bear-
ing that quickly wears loose and allows the stationary
portion to wabble out of its correct plane. This will cause
irregular firing or even misfiring. One may easily deter-
mine whether the cause of the misfiring is here or elsewhere
by steadying the timer with the hand. The remedy is to
bush the bearing, and, if possible, to make it longer.

54 TROUBLES AND REMEDIES § 2i

89. Incorrect Tlmingr. — With marine engines having
make-and-break ignition mechanism, even if the current is
sufficient and there are no leaks, the time of contact may be
too short, may be made at the wrong point in the stroke, or
may be broken when it should not be, owing to incorrect
timing. The timing may be tested by turning the fly-
wheel carefully in the proper direction, and noting when the
contact is made and at what point the spark occurs. By
scratching the flywheel at these points, when the engine is
nmning satisfactorily, it is always a simple matter to correct
any trouble in the time of sparking. Raising or lowering
the igniter pin without following any particular rule or with-
out knowledge of what one is doing is very bad practice,
and is more likely to aggravate than to remedy the diffi-
culty. It is evident that, in multicylinder engines, it is
quite important that there should be for each cylinder the
same relative time of making and breaking the contact, with
the same length of time in contact.

MISCEIiliANEOUS TROUBIiES

CT^OGGED MUFFLER

90. Habitual feeding of an excess of lubricating oil
to the engine will gradually clog the muffler with a mixture
of carbon and half -burned oil, which will reduce the power
of the engine and be very difficult to remove.

The symptoms produced are loss of power and inability to
speed up the engine when the mixture, compression, valve
timing, and ignition are known to be good; if the exhaust
pipes can be disconnected, the engine gives its full power at
once.

To remedy the trouble, take off the muffier and saturate
the interior with kerosene, after which the deposit can
usually be knocked, scraped, or shaken out.

§ 24 TROUBLES AND REMEDIES 65

GASOUXE USAKS

91, Probably the most dangerous trouble eicperienced
with marine engines is due to leaks in the gasoline tanks or
piping. They are more likely to occur at unions than any-
where else, and all joints and fittings should be soldered or
brazed, as well as screwed. Hence, the piping is not liable
to be broken at the threads, reinforced as they are with
solder. Unions should be very heavy, and should be exam-
ined for leaks carefully and often. Do not use a light or
match, but rub the finger around the joint, when, if there is
a leak, it may be detected by the odor that will remain on
the finger. Small leaks may be stopped temporarily by
means of cloth and shellac or soap. Insulating tape will be
found useless for the purpose, as the gasoline is a solvent
for the insulating material.

A good cord closely and tightly wound will be found serv-
iceable. Shellac and cloth bound on tightly and allowed to
dry with no gasoline in the pipe will be found very effective
in stopping leaks. It is necessary to be extremely careful
of fire in the presence or suspected presence of gasoline,
particularly when in the form of vapor and mixed with air.

WATEB IN EXHAUST PIPE OR MUEIXER

93. The exhaust gases from stationary gas or gasoline
engines contain a certain amount of moisture, part of whicli
is condensed and deposited in the exhaust pipe or muffler,
where it may become a source of trouble if no provision has
been made to drain these connections properly or if the
draining devices accidentally fail to perform their functions
as exx)ected. Especially during cold weather, when the
condensation in the exhaust connections is greater than at
more moderate temperatures^ it is advisable to inspect
closely the condition of the drain cocks. If neglected, the
level of the water in the muffler may rise to such an extent
as to prevent the exhaust gas from being expelled, first
causing loss of power and finally stopping of the engine.

66 TROUBLES AND REMEDIES § 24

In engines in which the governor acts on the exhaust valve,
and this valve is kept open while running under light load,
the trouble from water in the exhaust, when no charges
are admitted to the cylinder, is naturally intensified, on
account of the fact that a portion of this water is drawn
into the cylinder while the valve is open during the suc-
tion stroke. The presence of water in the exhaust connec-
tions is usually indicated by steam or water spray issuing
from the end of the exhaust pipe.

As before stated, water is frequently used for deadening
the noise of the exhaust by introducing it in a small steady
stream into the exhaust pipe and allowing it to be carried
off in the shape of vapor or spray with the exhaust gases.
In such cases, the draining devices require particular atten-
tion, because, in the case of failure to have a free outlet to the
drain for any part of the water not carried off with the exhaust,
the accumulation of water would in a short time be sufficient
to stop the engine.

WATER IN ENGINE CYLINDER

93. An accumulation of water in the cylinder — a con-
dition encountered more or less frequently in marine prac-
tice — will effectually prevent a gas engine from starting.
The water may get in through the exhaust pipe because
the installation is faulty, because the exhaust extends below
the surface of the water, or because there is a leak due to a
crack in the cylinder or to a broken and imperfect gasket
between the cylinder and the water-jacket. Running the
exhaust cooling water into the engine exhaust is a frequent
source of such trouble.

Provided the trouble from water in the cylinder is not due
to leaks the remedy is to remove the water entirely, by
means of absorbent materials, through any openings there
may be in the cylinder. The insulated electrode should then
be carefully dried out, the defect in installation remedied
by changing the exhaust piping to drain outboard, and, if
exhausting below the surface of the water, a vent provided
in the highest part of the exhaust piping.

§ 24 TROUBLES AND REMEDIES 57

PAIL.UKE TO GOVERX

94. If the connection between the governor and the
throttle is too long, the throttle may fail to close until the
governor balls have been moved out to an excessive extent
by the speed of the engine. In an old engine, wear of the
connecting links may produce the same result. Sometimes
there is an adjustable screw and nut connection between the
governor and the throttle, and this is easily adjusted.
Sometimes, however, it may be necessary to bend the rod
connecting the two. The throttle should be opened, and its
position when barely open should be marked in such a way
that it will be known when the throttle is reassembled. Then
the engine should be run idle and the position of the gover-
nor lever noted when the engine is running at the speed at
which it is desired that the governor should act. With these
particulars known, it is easy to shorten the rod to bring the
throttle to the desired position. It should be remembered
that a very slight opening of the throttle is sufficient to keep
the motor running

58 TROUBLES AND REMEDIES § ii

BEPAIBS

CTXINDER AND PI8TOK REPAIR WORK

BEFITTING PISTON AND PISTON RINGS

96. It is practically impossible to turn a piston in a lathe
so as to fit the cylinder in such a manner that the engine will
run properly even under a partial load. The best that can be
done is to have the cylinder bored slightly larger at the end
nearest the crank-shaft, so that the piston can be pushed in
easily from this end and will fit rather snugly at the other
end near the combustion chamber. To put the piston and
cylinder in condition to stand constant running under load
necessitates filing the surface of the piston by hand, as fol-
lows; See that both cylinder and piston are thoroughly clean
and free from dust or filings. Apply a liberal amount of
lubricating oil, place the piston in the cylinder, and attach
the connecting-rod to the crank-shaft. Start the engine, and
let it run idle for a while. As soon as the heat of the explo-
sion causes the piston to expand, it will begin to stick in the
cylinder, as the water-cooled walls of the cylinder do not
expand to the same extent as the piston. The sticking is
manifested by a pounding or knocking sound caused by
the very slight amount of play that necessarily exists in the
bearings of the connecting-rod at both the crankpin and the
piston end. As soon as this pounding appears, apply more
lubricating oil to the piston, and let it run for a few minutes in
this manner, without any load. Then stop the engine, take
out the piston, and wipe it dry. The portions of the piston
that bear hard against the cylinder will be indicated by
glossy spots, which should be carefully filed \\ath a smooth.
Hat file, removing ^)iily a little at a time. To facilitate filing,

§ 24 TROUBLES AND REMEDIES 59

remove all traces of lubricating oil by means of kerosene.
After filing the piston surface in this way, clean the piston,
put it back in the engine, and start up again. It will be
noticed that it is now possible to run the engine for a longer
period without any pounding in the cylinder and perhaps to
be able to put on a light load for a short time. Do not
keep the engine running with any load for any length of
time, so long as there is any pounding noticeable. This
operation may have to be repeated from four to six times,
depending on the skill of the operator, before the engine can
run steadily with the usual maximum load.

These instructions apply also to cylinders that have been
rebored and fitted with new pistons, as the conditions in this
case are the same as in a new cylinder.

96. The piston rings also require fitting in a similar
manner, and in this connection the following points must be
observed : Before placing the rings in the grooves, each ring
should be tried, to ascertain that it fits in the groove for
which it is intended. If the ring is found too thick, place it
on a straight board, and hold it in place by fastening three or
four nails within the ring, driving them down until the heads
are slightly below the top of the ring. Having thus secured
the ring on the board, file it carefully and reduce its thickness
so as to get an easy sliding and uniform fit in its groove.

The rings can now be put in place by opening them and
slipping them over the piston from the closed end. In doing
so, the rings should be expanded and twisted as little as pos-
sible. The first ring must be placed in the groove farthest
away from the closed end of the piston, the others following
in order. If, after runnirfg the engine with new rings for a
short time, the rings show that they bear hard and unevenly,
the hard-bearing portions must be touched up with a fine
file. Should it become necessary at any time to replace a
broken ring located between other rings, the use of small pieces
of thin sheet tin will be found of advantage. They are
slipped in between the inside of the ring and the outside of
the piston, at a convenient point of the circumference, so as to

60 TROUBLES AND REMEDIES §24

keep the ring evenly expanded and enable it to be moved
laterally over other rings already in place to the groove for
which it is intended. Having reached its groove, the pieces
of tin are withdrawn, and the ring is allowed to enter the
groove.

A ring that, from undue expansion or twisting, has lost
its original diameter will not bear evenly and vdll wear out
the cylinder in a short time, causing leakage and loss of
power.

REPAIRING CRACKED WATER-JACKET

97. Neglect in draining the cylinder jacket when stop-
ping the engine after the day's run may result in cracking
the outer shell in cold weather, owing to the freezing of the
water. It is very seldom that the inner cylinder is damaged
in such a case, but if it should happen to be injured, the
casting is generally rendered useless and must be replaced
with a new one. The outer shell, being much lighter than
the cylinder itself, provides a safeguard against damage to
the latter, and in most cases, if the cylinder and jacket are
cast in one piece, it will be possible and economical to repair
the cracked shell.

The following directions arc intended to cover repairs for
various kinds of cracks, and apply to cracks in cylinder
jackets proper, as well as to cracks in the outer shell of cyl-
inder heads or valve casings of larger sizes. In large cast-
ings it will pay to repair the part, rather than replace it with
a new one ; but with small castings it may be found to be more
convenient and cheaper to replace the heads or casings
with new ones.

Fig. 4 {(i) and (d) shows a cylinder, the outer shell of
which has been burst bv frost. The crack a b extends only a
portion of the entire length. After the ice has been thawed
and the jacket emptied, the first thing to do is to drill two
holes a and b, ahotit \ inch in diameter, at the ends of the
crack. The purpose of these holes is to prevent the crack from
extending any farther on account of the chipping necessary

TROUBLES AND REMEDIES

ri the next operation. Then take a chisel about -^ inch to \
rxch wide and cut a groove along the line of the crack, dove-
^led as shown at c in the sectional view of the cylinder and.
^cket, Fig. 4 (d), the groove being widest at the bottom.

Fk;. 4

Next secure a piece of \ inch round copper wire, well annealed,
and hammer it tightly into the groove. By careful calking
a crack of this nature can be made perfectly tight.

98.* Fig. 4 (a) also shows a crack de extending from one
of the water ports to the outer end of the cylinder. In such
a case, it will be necessary to shrink a steel band / on the
end of the cylinder, before the crack is chipped out and
calked in the manner just referred to. Use a flat steel band
about \ inch by f inch, and be sure that the finished end of the
cylinder projects about ^ inch beyond the band when in
place.

If the crack extends over the entire length of the jacket,
as shown at ^/f, it will require additional bands i and/ as
shown. If the cylinder has finished collars at the ends, as is
frequently the case, it will not be possible to slip the ringj
over the end of the cylinder into its proper place, unless an
auxiliary band >fe, open to the extent of about \ inch as
shown at /, is first placed on the cylinder. This band ^ must,
of course, be thick enough to make up the difference in
diameter of the cylinder body and the finished collar. In
shrinking rings on a cylinder, they should be heated to a dull
red heat and must be handled dexterously, as the cooling
takes place rapidly and the ring may shrink so as to stick

62 TROUBLES AND REMEDIES § 24

before it reaches its position if not applied quickly. After
the bands have been put in place and have been found to be
tight, the cracks should be grooved and calked as directed.

If a crack should devejop in the surface of a joint between
the cylinder and one of the valve casings attached to it, and if
this crack crosses the port through which the entering charge
or the exhaust gases pass, as shown at ;//;/, Fig. 4 (a), it \^*ill
be practically impossible to repair the casting in such a plan-
ner that a packing can be made to stand, and the only remedy
is to replace the damaged part with a new one.

99. Another method of repairing a short crack in the
surface of the jacket wall consists in applying a piece of
steel boiler plate, about -1^ inch thick. Before putting on the
plate, two \ inch holes should be drilled at the ends of the
crack, to prevent it from going farther, and a V-shaped groove
cut along the crack from end to end. The plate must be bent
so as to conform to the shape of the cylinder jacket. A pack-
ing of thin asbestos wick soaked in white-lead paste is now put
in the V-shaped groove, after which a packing of sheet asbestos
the size of the plate and dipped in water is placed over the
surface to be covered by the plate. Now apply the plate,
which is held in place by a number of \ inch to |- inch
screws, the size of the screws depending on the thickness of
the water-jacket. The screws should be about 1 inch apart, 1
inch on each side of the crack ; and, if possible, the tapped
holes in the jacket, in order to prevent water from leaking
past the screws, should not be drilled all the way through.
If the jacket is so thin as to make it necessary to drill the
holes all the way through, each screw head must be packed
with hemp or asbestos soaked in white lead.

100. An automobile-engine water-jacket split by freez-
ing is also sometimes repaired by the following methods:
If the crack is very small it may be rusted up. For this pur-
pose, a saturated solution of salammoniac is made and
poured into the jacket. A plug, screwed into one of the
water openings, is drilled and lapped for a small tube, by

§ 2-t

TROUBLES AND REMEDIES

ooooO<^

which air pressure is put on the liquid in the jacket by means
of a tire pump. The cylinder is so laid that the crack is at
the bottom, and after several hours it will be found that the
edges of the crack have rusted solid from the action of the
salammoniac.

Another method of closing a crack is that shown in Fig. 5.
The process is to drill and tap a series of | or ^ inch holes
as close together as practicable for
the entire length of the crack,
the first and last holes being at
the extreme ends of the crack, in
order to prevent it from extending
farther. Thesis holes are plugged
with cast-iron plugs turned and
threaded for the purpose, and the
job is completed by rusting in
with the salammoniac solution as
just described. When brazing
facilities are available, it is much ^
better to braze a cracked cylinder
than to try rusting it, as the chances of securing a permanent
repair are much better.

PlO. 6

MISCEIiliANEOFH REPAIRS AND RENEWAIiS

BEPAIRINO BROKEN ENGINE BED

lOl. The breaking of the studs or bolts that hold the
connecting-rod box to the rod will often wreck an engine,
involving the breaking beyond repair of the piston, cylinder,
and even the bed. As the bed is usually a rather costly part
to replace, it is frequently found possible to repair it with the
aid of a strong steel rod properly applied.

A break repaired in this manner is shown in Fig. 6. It is
possible to make this kind of repair only when there is a
clean separation of the casting in two pieces; if the bed is
broken into a number of small pieces, it must be replaced ^nth
a new casting.

64 TROUBLES AND REMEDIES § 24

To repair a bed, as shown in Fig. 6, first be careful to
preserve the two pieces so that they will fit exactly when
put together, using every precaution against careless hand-
ling and further damage to the surfaces that form the joint
Then investigate and find the best way in which the steel

-'^-'^-V^:---J

Pig. 6

rod should be run so as to take hold of the strongest avail-
able part of the bed.

The figure shows the rod running inside of the double wall
casting, a 2-inch rod being used in a space 3 inches wide, and
being secured by two nuts at each end. The line ab
indicates the break of the bed casting. At c and d are cast-
iron washers made to conform to the shape of the casting and
providing a straight surface for the nuts of the bolts e to rest
on. It is important that the nuts should bear squarely
against these washers to avoid any excessive stress on the
bed casting. Jamb nuts or some other locking device must
be provided to prevent the nuts that hold the bed together
from becoming loose as a result of the shocks and jars to
which the casting is subjected while the engine is running.
A frequent inspection of the tightness of the nuts is
advisable.

REGRINDING VALArES

102, It is not often that inlet valves must be
reground, because they remain comparatively cool under the
influence of the incoming charge, and, moreover, the seats
are not exposed to the erosion of burning gases. Exhaust
valves, on the other hand, require regrinding at interv^als,
depending somewhat on the temperatures in the cylinder,
and to a large extent on the material of which the exhaust

§ 24 TROUBLES AND REMEDIES 65

valves are made. Ordinar}' mild-steel valves must be
regTound quite frequently. A much better material is an
alloy of nickel and steel containing a high percentage of the
former metal, usually about 25 per cent. Such an alloy as
this has a very small coefficient of expansion, and is less
subject to erosion due to the heated gases. Moreover, it is
not liable to warp out of shape.

For large engines, and occasionally for small ones also,
cast iron has been found to be a very good material for the
exhaust valves. If cast iron is used, the stems and heads
are made separate; the stems are made of steel, and the
heads are riveted on the stems. The only drawback to cast
iron for this purpose is that it has not the strength of steel,
and the valve head must be of unusual thickness, which, of
course, adds to the weight and inertia of the valve.

103. Inlet and exhaust valves are reground with emery.
If an exhaust valve, the spring is first slipped off to make
sure that there is no sidewise pressure on the stem to pre-
vent a true bearing of the valve on its seat The emery is
mixed with oil until it forms a paste, and is applied freely
to the surface of the valve and its seat. Extreme care must
be taken to prevent any of the emery from getting into the
interior of the cylinder, where it would quickly ruin the pis-
ton and the cylinder walls. In some cases, a plug of waste
can be thrust into the valve chamber between the valve and
the piston; but, if the chamber is not long enough for this,
the work will have to be watched carefully, using an elec-
tric light, if necessary, to see that none of the paste works
away from the valve toward the piston.

104. If the valve seat is badly out of true, the opera-
tion of grinding may be begun with emery of medium
coarseness; but this is seldom necessary, for the reason that,
before the valve had reached such a condition, the cylinder
in question would have lost almost all of its power. In any
case, the work is finished with fine flour of emery. Tho
emery being applied, the valve is set into its place in tho
valve seat, and a screwdriver is used in tho slot in tlio vaUv

66 TROUBLES AND REMEDIES §24

head to rotate the valve, which should be worked by quar-
ter-turns back and forth with moderate pressure, and should
be lifted at frequent intervals to allow the paste to work in
between the valve and its seat. In order to grind the
valve evenly all around, it should occasionally be advanced
a quarter- turn, and the grinding-in process continued.
When the grinding is almost finished, the pressure should
be comparatively light.

If the valve has been pitted, it will not be necessary to
grind it until the pits have entirely disappeared, so long as
there is a good bearing around them.

When the work is finished, the ground portion of the
valve should have a smooth, dull appearance, and neither the
valve nor its seat should at any point be bright, as this
would indicate that metal had been rubbing on metal with-
out emery between.

105. After the valve has been reground several times,
it is likely to have settled so much lower in its seat as to
cause the valve stem to remain in contact with the push rod
when the valve is supposed to be seated. When the valve
is closed, the clearance between the valve and the push rod
should be fully equal to the thickness of an ordinary visiting
card. If the distance is less than this, any slight irregular-
ity in the cam, or some slight springing of the metal parts
when the engine is running, might bring the valve stem and
the push rod together and cause the valve to be opened
slightly.

106. In an old motor it may be found that the bushing
or sleeve in which the valve stem runs is worn to such an
extent as to permit considerable sidewise movement of the
stem. A valve in this condition will still operate if it has
been carefully ground, but it is likely to need grinding much
oftener than if it were truly guided by its bearing. It
should never be ground with the spring washer merely
blocked up; the ^spring should in each case be wholly
removed.

§24

TROUKLES AND REMEDIES

KEXEWING BABBITT-METAL. LINERS

107. When a babbitt-lined bearing becomes over-
heated and the trouble is not noticed in time, the soft metal
of the lining, which may have a tin or a lead base, will melt
and run out of the box. While in some engines the Babbitt
metal is cast directly in the rough bearings of the engine
bed, it is the general practice in a first-class engine to bore
out the bearings in the bed and fit them with cast-iron or
bronze boxes lined with Babbitt metal.

If the journals of the shaft are in good condition after the
metal has been melted and run out of the box, the method
of rebabbitting the bearing is the same as was followed at

Fig. 7

the time the box was made at the factory. To reline the
box in such a case, proceed as follows: Remove all traces
of the original lining from the box. While melting the new
metal in the ladle, place the box on its end on a flat-finished
surface, and insert an arbor, from ^ ^^ i ^^^^ smaller in
diameter than the journal, in the center of the box, being
careful to have an evenly divided space all around the out-
side of the arbor. The box a being made in halves, as
shown in Fig. 7, place shims b, b made of cardboard -jV inch
thick between the joints, having the shims extend well into
the space around the arbor so as to allow only a thin strip of
the Babbitt liner c to connect the halves of the lining, in

70 TROUBLES AND REMEDIES g ;

der head to the cylinder, screw the nuts on the studs, a^
tighten them gradually and evenly. After everything la ;
been put in order, start the engfine and run it under a li^"^
load or idle, until it begins to warm up, when it is fou^r;
that the nuts can be tightened up still more. This should t
done promptly, as neglect to take up any expiuision by thi
heat of the combustion may cause the new packing- tc
become leaky soon after it has been put in.

111. While the packing surfaces must be true and
straight, it does not follow that they should be as smootii
as glass. Experience has shown that a grooved packing-
surface gives much better results than a perfectly smooth
one, although many manufacturers seem to take great pains
to make the packing surfaces as smooth as possible. In
many cases, troublesome joints have been permanently
cured by the judicious application of grooves in the metal
surfaces. The packing fills the grooves and prevents the
escape of gas between the packed surfaces. Fig. 8 shows,
in dotted lines, the positions of the grooves c, which in small

^ surfaces may be -^ inch deep and

y? — j-i— — ~- , ^ _^ jjj^jj wide. On circular sur-

■ faces, such as the packing surface
] between the cylinder and the cyl-
inder head, shown in Fig. 9, the
grooves should be cut concentric,
and should not come opposite each
other; biit, when placed together,
the groove a in the cylinder 3 should be half way between
the grooves in the head c, as shown,

lis. Whenever possible, the edge of the packing should
be protected against the pressure by a projecting rim J, that
enters the end of the cylinder, as shown in Fig. 9. If no'
•originally provided by the maker of the engine, it will pay the
user to have the rim attached by riveting it to the cylinder
head, in case of persistent trouble with the packing of this
joint. The depth of the projection </ should be about ^ inch,
and it should fit rather snugly in the bore of the cylinder,

§24 TROUBLES AND REMEDIES 71

but not so that much force will be required to insert the
head.

113. As the material employed for gaskets is usually
ssbestos alone, or asbestos, wire gauze, and graphite or similar
filler, a knife or pair of scissors makes very little impression
K>n it; but it can be cut out very readily if laid on the cylin-
der head and carefully cut around on the outside with a
light, flat-faced, round-peen hammer. The holes can then
also be cut with the round peen. Great care should be exer-
cised not to pull out any wires from gaskets in which wire
gauze is used. The wires should be cut off very carefully.

If the material used is ordinary asbestos paper -j-^^, ^, -^^^
or even -^ inch thick, it should be thoroughly soaked with
linseed oil, either raw oi; boiled, and dusted carefully with
powdered or flaked graphite, or with graphite foundry
facing that contains talc, etc. , which is a very good substi-
tute. It is a good plan to let this dry a little while in the
air, when it becomes much tougher. It should not, how-
ever, be allowed to get too dry. When put in place, the hold-
ing nuts should be" screwed down carefully, going over them
several times and screwing down opposite nuts instead of
adjoining ones. The engine should then be started and run
a few minutes, with the compression relieved and the circu-
lating water turned off, in order to heat up the engine and
assist in dr3dng out the oil or any dampness in the gasket.
The nuts should then be tightened carefully, when the water
may safely be turned on. If these directions are followed
closely, and the gasket is not defective, it should last a long
time. The oxidation of the linseed oil will make the gasket
tough, and if it is dusted with graphite every time the cylin-
der head is removed it should be very durable.

In using a gasket of asbestos and wire gauze having mate-
rial on one side to make it adhere to the cylinder top, the
opposite side being treated with graphite, there is no need
of treating the gasket with linseed oil. A gasket of this
sort is almost indestructible when care is exercised in tight-
ening the holding nuts when the gasket is new.

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■ ' 1

POWER DETERMINATIONS '

TESTING

EQUIPMENT FOR TESTS

OBJECT or TEST

!• There are occasions when it is necessary or advisable
to make a careful study of the performance of a g^as engine
tinder various conditions of working. For example, a
manufacturer may be looking for defects, in order to apply
the proper remedies; or, he may desire to possess a record,
in order to offset possible complaints from purchasers
regarding the non-fulfilment of the requirements of contracts.
Also, a prospective buyer may want a test made for purposes
of comparison with other engines, or of determining the make
best suited to his needs; or, a user may have trouble with
his gas engine and make a test to locate the difficulty, and,
after repairs are made, make another test to ascertain
whether the engine is in order. In cases like these, a prop-
erly conducted test will bring out the good and the bad
features of an engine as nothing else will. A thorough test
will enable the engineer to determine whether the engine is
wasting power, and, if so, to discover the cause; to ascertain
whether the engine is correctly designed with regard to the
sises and proportions of valves and passages, and whether
the valves are properly set; and to locate many other faults
that wotdd probably be overlooked and that continuous
nmning would perhaps never reveal.

BT INTSmiATIONAL TCXTBOON COUPANT. ALL IIIQHT9 RCSCRVKO

225

2 POWER DETERMINATIONS §2.5

While, however, a complete test is very often desirable, it
is not always necessary. Perhaps all that may be desired
will be the power that the engine can deliver to the
machinery it is intended to drive, in which case a brake test
only will be required. In order, however, that every detail
may be understood, a test in its entirety will be described, so
that whatever portions are required in actual practice may be
used when wanted.

2. In a gas-engine test, the following results are usually
determined in order that the performance of the engine may
be ascertained: (1) the brake horsepower; (2) the indicated
horsepower; (3) the quantity of gas consumed per brake
horsepower per hour; and (4) the lost energy due to heat
carried away through the exhaust, by the jacket water, and
by radiation from various parts of the engine.

The Indicated horsepower (sometimes abbreviated to
I. H. P.), so called because it is measured by means of an
indicator, is the power applied to the piston of the engine
by the explosion and expansion of the gases.

The delivered horsepower (abbreviated to D. H. P.)
is the name given to the power delivered by the engine to the
belt or the machinery it is driving. The delivered horse-
power is frequently called the brake horsepower (abbrevi-
ated to B. H. P.), because it is measured by means of a
brake.

From the measurements that must be taken to obtain the
data just given, the performance of any engine can be
readily analyzed.

APPARATUS USED IN TESTING

3. Prony Brake. — To make a test as just indicated, it is
necessary to have an apparatus similar to that shown in
Fig:. 1. which is a view of a form of absorption dynamometer
known as the Prony brake and used to obtain the brake
horsepower. The Prony brake consists of an iron strap a, to
which are attached, with screws, a number of wooden friction
blocks b. To each end of the strap is bolted a cast-iron

POWER DETERMINATIONS

block Cy so that the brake may be tightened by means of th
bolt d and the nut e. Bolted to a are two boards /, /, formini
the lever arm, or brake arm, and carrying at one end th
steel knife edge g. This knife edge rests on a flat piece
iron A, through which the pressure is transmitted to
platform scale k by means of the stand /.

4. Rope Brake. — A simpler form of brake, and oi
suitable for light powers, is shown in Fig. 2. The bra^^^
proper consists of four or five ropes, as shown at r, or ^
piece of leather or canvas belting. The weight w is fasten ec/
to one end of the belt and a spring balance b to the other.

The lower end of the
balance is attached to
a hook h screwed fast
to the floor. If the
pulley were perfectly
free to turn, the read-
ing on the balance
would be equal to the
weight of w\ that is,
if the weight of w is
50 pounds, the pointer
on the balance' will be
at 50.

As the pulley is
turned by the engine, the weight w is drawn upwards by
the friction of the strap until the strap slips on the pulley.
The total amount of pull will then be indicated by the
decrease in the reading of the balance, or by the difference
between the weight of w and the balance reading. Thus,
if the balance reads 20 pounds, the pull on the belt will be
w - 20, or 50-20 = 30 pounds.

It is evident that, in either form of brake, the energy
absorbed is converted into heat by overcoming the force of
friction between the brake and the revolving wheel. In the
simple forms of brake mentioned, it is a serious probletn to
take care of the heat generated at high speeds, and for this

Fig. 2

POWER DETERMINATIONS 5

on such brakes cannot be used on gfas engines except
short periods of time, unless the heat is absorbed by

iT.

I The Alden Dynamometer. — The Aid en dyna-
neter is a type of brake that can be run continuously

very little attention. Fig. 3 shows an elevation and part
ion of such a dynamometer. It consists of the hub and

casting a, the shaft d to which the casting is keyed, the
;ing plates r, r, and the thin copper plates flf, d. The cop-
plates are clamped at the outer edges between the two
ling plates, and at the inner edges between rings and
aubs of the housing plates. The copper plates are thus

parallel and close to the disk a, in which are radial oil
>ves for conducting oil all over the bearing surface
reen the disk and the copper plates. Oil is fed to these
>ves from the oil cups e, e, through the pipes /, / and the
)assages g,gy in the housing hubs. The oil that works
ray out around the hub to the recesses A, h is drained off
ugh the pipes /, /. The copper plates and the housing
5S form chambers /,/, which are filled with running water
n the apparatus is in use. Water enters the bottom of
e chambers through the pipe ^, the automatic regulating
e /, and the pipe m. From the pipe tn, the water passes
agh openings in the bottom casting n into the cham-
j\j in the housing. The water fills the chambers, rises

the space o, and flows out through the pipe p. The
ir pressure in the chambers j\ j forces the copper plates
nst the disk a, and sets up a friction that heats the cop-
plates and tends to turn them with the disk. The heat
rried off by the water, while the tendency of the copper
js and housing to turn is balanced and weighed by the
:ht g on the arm r. If the water pressure increases, the
r goes up and partly closes the automatic valve /, thus
)ring the equilibrium.

^namometers of the Alden type have been built with
I or four disks and large enough to absorb 2,000 to
) horsepower at from 200 to 300 revolutions per minute.

POWER DETERMINATIONS

<•

§25 POWER DETERMINATIONS 7

6. Tlie Dynamo as a Dynamometer. — One of the

best means of absorbing work from a gas engine and con-
verting it into heat is to use a dynamo, which for dynamome-
ter purposes is preferably coupled to the shaft of the gas
engine — that is, the dynamo and engine are direct-connected.
The electricity delivered by the dynamo is absorbed by pass-
ing it through a suitable resistance. The product of the
readings of the ammeter and voltmeter placed in circuit
gives the number of watts generated, which, divided by 746,
will give the horsepower generated by the dynamo. To
obtain the delivered, or brake, horsepower of the gas engine,
divide this result by the efficiency of the dynamo, which has
been previously determined at the load required.

7. Tlie Gas-Eng^ine Indicator. — In making a test of
a gas engine, the power exerted on the piston by the explo-
sion and expansion of the charge is measured by means of
an instrument known as an indicator, and shown at /, Fig. 1.
The indicator used on gas engines is very similar to that
used on ordinary steam engines; in fact, the same indicator
is often used for both, with auxiliary attachments to adapt
it to the gas engine. The piston of a gas-engine indicator
should, however, be very light in order to give the best
results.

The purpose of the indicator is to determine the pressures
in the engine cylinder at all points of the stroke, and to
record these pressures in the form of a diagram on a paper
or a card. In the case of the gas engine, the principal reason
for obtaining an indicator diagram is to determine the cor-
rect setting of the valves and the timing of ignition. The
mean pressure may also be found, approximately, by the
indicator diagram; but the shock of the explosion, the high
speed of the engine, and the inertia of the indicator-pencil
motion tend to reduce its accuracy for that purpose.

8. Fig. 4 shows the general appearance of an indicator.
The instrument consists essentially of a cylinder a contain-
ing a piston and helical spring for measuring the pressure,
the lever b for transmitting the motion of the piston to a

POWER DETERMINATIONS

S!i

pencil point f , and the drum d that carries the paper, or card,
on which Ihe diagram of the motion is drawn. The card ( is
held close to the drum by the clips shown at /, /, so that the
pencil can easily trace the outline of the diagram.

In Fig. 5 is shown a section of the same indicator. The
piston, shown at g, must work in the cylinder as nearly
frictionless as possible, the spring h being the only resislaoee
to its upward motion. The spring is calibrated, that is.
tested so as to determine the pressures required to move |
the pencil c to various heights against Ihe resistance of the
spring. The pressure, in pounds per square inch, thai ii 1
required to compress the spring sufficiently to allow lli« ||
pencil to be moved up 1 inch is called the scale of the n
sprInK- It is, therefore, possible to find the pressure in "
the cylinder by the position of the pencil point when the I
scale of the spring is known. By turning a small cock, shown
attf. Fig. 1, in the pipe connectingthe indicator to the ensise

POWER DETERMINATIONS 9

cylinder, the gas pressure in the engine cylinder may, at
pleasure, be admitted to or shut ofE from the indicator.
When the gas pressure is admitted through the channel s,
Fig. 5, it causes the piston ^ to rise. The helical spring A

is compressed and resists the upward movement of the
piston. The height to which the piston rises should then
indicate correctly the pressure in the engine cylinder; and as
this pressure rises and falls, the piston g must rise and fall
accordingly.

9. To register the engine -cylinder pressure, a pencil
might simply be attached to the end of the piston rod, and
the point of the pencil made to press against a piece of
paper. It is desirable, however, to restrict the maximum
travel of the piston to about i inch, while the height of the
diagram may advantageously be la to Ij inches. To give a
long range to the pencil while keeping the travel of the
piston short, the pencil is attached at c. Fig. 5, to the long

10 POWER DETERMINATIONS §25

end of the lever b. The fulcrum of the lever is at /, and the
piston rod is connected to it at k^ through the link /. The
pencil motion is thus much greater than the travel of
the piston g\ for most indicators, it is four, five, or six times
as great. The point c is made to move in a vertical straight
line by the arrangement of the links 2, /, and g,

10. The indicator, however, must not only register pres-
sure, but must also register them in relation to the position
of the piston. This registering is accomplished by means
of the cylindrical drum shown at d^ Figs. 4 and 6. Th
drum can be revolved on its axis m by pulling the cord
that is coiled around it. When the pull is released, th
spring Oy Fig. 5, turns the drum back to its original position
If the cord n is attached to some part of the engine that ha
a motion proportional to the motion of the piston, th
motion of the drum must also be proportional to the motio
of the piston. If the cord were attached directly to th

piston or to some part having the same motion as the pistoi 3,

the drum d would have to be so large that it would be cum^cn-
bersome and the diagram correspondingly long and difficm^-Jt
to handle. For these reasons, the drum is made small ar=:^d
a device is employed for reducing the motion of the dru_ -m
so as to give a convenient length of the diagram. Tb^is
device, called a rediuing motiatiy will be explained later.

The indicator shown in Figs. 4 and 5 can be used in taki^Kng
diagrams from a steam engine or any other engine in whS. <h
the pressure is not so great as in the gas engine. In orSler
to do this, the piston g and its rod are unscrewed at p anc3 a
piston that just fits the cylinder at p is attached. The a:i"ea
of the cylinder at this point is just twice that of the piston. £;
hence, only one-half as much pressure per square inch ^^i
be required to produce the same pencil movement.

11. To attach the indicator to the engine, a hole is drilled
in the cylinder head into the clearance space of the engine
and tapped for a i-inch pipe, shown at «, Fig. 1, with an
elbow turned up and carrying a nipple and a valve o next to
the indicator. The lower end s, Fig. 5, is inserted in the

§ 25 POWER DETERMINATIONS 11

fitting attached to the valve and the connection r is tightened
by means of the handle / shown dotted at u. When the indi-
cator is to be used, a card or a piece of blank paper of con-
venient size is placed around the drum, with the ends of the
paper projecting from behind the clips through the space
between them. The drum revolves with a motion propor-
tional to the stroke of the engine, and the pencil moves up
and down with a motion proportional to the pressure in the
cylinder. Hence, by holding the pencil against the paper it
draws a diagram recording these two quantities in such a
way that they can be measured for every point of the stroke.

12. . Manufacturers of indicators usually supply a special
paper for use on the indicator, known as **metallic paper,"
which is made by coating ordinary paper with a special prep-
aration that will turn black when rubbed with a brass wire.
The indicator pencil may then be replaced by a piece, of
ordinary brass spring wire, and the trouble of keeping a
pencil sharp is obviated. Although the preparation of this
paper is usually considered a secret, a coating of zinc oxide
(zinc white, or Chinese white) will answer the same purpose.
The zinc oxide is mixed with some gum solution or glue, and
spread evenly over the surface of the paper. The paper is
then allowed to dry, and is afterwards subjected to pressure
for a day or two to remove the tendency to curl. The sur-
face should be smooth and free from lumps or ridges, as
these will cause unnecessary friction. Diagrams made on
metallic paper are much more distinct than those made in
the old way with a hard pencil.

13. The indicator spring to be chosen depends entirely
on the initial pressure of the exploded charge. The scale of
the spring should be such as to give not over \\ inches verti-
cal movement to the pencil for the highest pressure to be
obtained on the cylinder. For instance, if the initial pres-
sure is 175 pounds, a 100-pound or 120-pound spring should
be chosen. The scale of the spring (100 pounds) indicates
that the pencil will move 1 inch for each 100 pounds
pressure per square inch on the piston. In general, it is

12 POWER DETERMINATIONS SSS

advisable to select a spriag that will give a diagram betvees
ll and I( inches high. A diagram less Chan 1^ inches in
height is objectionable, for it is too small to show properly
the valve setting; hence, in such cases, it is advisable to use
a spring of lower scale. It may be found necessary to pro-
vide the indicator with a safety stop, so that the piston wiD
not rise too high and thus cause damage to the spring and
other moving parts.
The cylinder of the indicator /, Fig. 1, is connected to the
compression space by i-indi
gas pipe, as shown, a ping
cock o being inserted between
the engine and the indicator.
A bunch of waste satniattd
with water should be tied
around the indicator at and
kept wet constantly, in order
to prevent damage to the in-
dicator from overheating.

]4. Reducing Motions.

There are many devices-
known as reducing mo-
tlouB — for reducing the mo-
lion of the engine piston to
one suitable for the indicator
drum. The reducing wheel r.
Fig. 1, is perhaps the most
*'"*^ convenient for general use.

It is shown on a larger scale in Fig. 6; the cord a is attached
to a rod on the piston, and the cord b is attached to the
indicator drum.

The other end of the cord a is attached to the large wheel
and wound several times around it. As the cord a is pulled
by the piston, it unwinds, turning the large wheel and the
small wheel at the same time. The spindle of the small
wheel has a screw thread of a pitch equal to the thickness
of the cord, so that the arms of the cord guides, which Me

§25 POWER DETERMINATIONS 18

held from turning about the spindle, are moved, with each
revolution, along the spindle a distance equal to the thick-
ness of the cord. Hence, the cords never wind over them-
selves, but each cord is laid up in a continuous coil on the
pulley as the other unwinds from its pulley. The pulleys
being fastened together, the smaller turns with the larger;
and, as the cord a unwinds one turn from the large pulley,
the cord d unwinds from the indicator drum and winds one
turn on the smaller pulley. Hence, the motion of the two
cords is proportional to the circumferences or diameters of
the two pulleys.

The smaller pulley can be removed and replaced by one
of several others of different sizes. The proportions of the
two pulleys should be such that the length of the diagram
will be between 22 and 82 inches. Thus, if the stroke of
the engine is 12 inches, and the desired length of the
diagram is 3 inches, the diameter of the larger pulley should
be four times that of the smaller.

15. The small sketch at the right of Fig. 1 illustrates the
method of connecting the cord from the reducing wheel to
the engine piston. A i-inch iron rod / is bent at right
angles, as shown, and attached to the inside of the piston by
two or three small machine screws. The end attached to
the piston should, of course, be drawn out flat before the
holes for the screws are drilled. A hook is made at m, to
which the cord from the reducing wheel is to be attached.
The wheel can be placed at any convenient point between
the point m and the indicator.

16. Reducing motions that employ gears are frequently
used. Such a reducing motion, attached to an indicator, is
shown in Fig. 7. This motion really consists of two wheels;
on the larger one, shown at a, is wound the cord that is
attached to the rod on the piston, and from the smaller
one d runs the cord to the indicator drum. A spring in the
horizontal case c acts on the pulley a through the bevel
gears, resisting the pull of the piston on the string, on its
outward stroke, and drawing in the string on the return

IftS— 28

POWER DETERMINATIONS

§25

stroke, thus always keeping the string tight. In the same
way, the spring in the indicator drum d keeps the string
tight between the drum and the pulley b. Frequently, the
reducing wheel is attached
directly to the body of the
indicator, as shown in Fig. 7,
thus avoiding the necessity
of fastening it to the engine, ___
as shown in Fig. 1. Whei^^H

the reducing wheel is at

tached directly to the indi
cator, the cord frotn th^^K
wheel b. Fig. 7, to the ind^^E-

cator drum d is short an ^

direct, making a >•- ^

with very little lost motio^^n.
The wheel a is very pasi ~ -\ j
detached from the mecha. -i-
ism, and is one of seveir— aj
different sizes furnished wm. tb
P'o- 1 the apparatus, and used ^n

engines of diSerent lengths of stroke. The cord guides- is
arranged so that it can be turned to any position in its hc^n-
zontal plane and fastened there, when it has only the vertSca/
motion necessary to lay the cord on the wheel uniformly.

17. There should be some means arranged to stop tbe
motion of the drum when not in use. This is easily done
by dividing the cord from the indicator drum to the reduciaj:
wheel, and connecting the two portions by means of the
loop / and hook a. Fig. 8,
The knots should be so .
tied that they will not
slip. The small piece
of wood b makes a very
neat arrangement about which to make the loop, as it will
not slip and is easily united, and the length of cord is readily
adjusted. In case the reducing wheel is connected to the

J-rC^g^-

pio. a

§25 POWER DETERMINATIONS 15

indicator, as shown in Fig. 7, the hook is placed in the cord
runnins^ from the reducing wheel to the rod on the piston.

18. Gas Measor/Bment. — The gas that is supplied to
the engine should be measured by a proving meter con-
nected as shown at x. Fig. 1. Such a meter has a large dial
and gives the number of cubic feet per hour from an obser-
vation of 1 minute, as well as the total gas consumption over
any period of time. The gas from the meter should pass to
the engine through an india-rubber gas bag yy or some other
form of pressure equalizer. In gasoline- or oil-engine tests,
the fuel must be weighed.

19. When it is necessary to measure the heat wastes
and calculate the ratio each bears to the heat supplied, the
heating value of the gas should be obtained. Quite fre-
quently, the gas company has a record of the average heat-
ing value of the gas it manufactures. If it has no such
record, a sample of the gas should be sent to a laboratory to
be properly tested for this value. This determination is
absolutely essential to a complete test, or for a comparison
of engines tested with different grades of gas.

20. Cooling- Water Tanks. — In order to ascertain, the
amount of heat carried off by the jacket water, it is necessary
to know the weight of water that passes through the jacket
and the rise of temperature caused by the heat of the engine.
The weight of water may be measured in one of two ways:
the water may be weighed directly, by means of a platform
scale, using a tank or barrel set on the scale platform; or, if
the scale is not convenient, the volume may be measured
and the weight calculated. Since a certain volume of pure
water at the same temperature always has the same weight,
it is a simple matter to measure the water directly in pounds.
For this purpose, the measuring tank ^, Fig. 1, is so con-
structed that the depth of the water, in inches, gives its
weight, in hundreds of pounds, when multiplied by 2. The
tank is made of plank, and measures 37i in. X 37i in. inside
dimensions. The height may be from 2 to 3 feet, as found
most convenient. The stick s is marked off in inches or

POWER DETERMINATIONS

i inches as desired. This is used for measuring the depth
of water in the tank. When the bottom of the tank is level,
each 2 inches in depth indicates 100 pounds of water, and
each a inch 25 pounds of water. If the stick is marked off
in tenths of an inch, each tenth will indicate 5 pounds d
water. These dimensions are computed for water at a
temperature of 110° F, If a smaller tank or more accurale
measurement is required, a tank 26i in. X 26i in. will pve.
25 pounds for each inch on the stick, 100 pounds for eadi
4 inches, and 5 pounds for each i inch.

When the quantity of water used is small, or when wj
accurate determinations are to be made, the water shonld
be weighed. This can be done quite
readily by using two receptacles and
changing them at the moment of taldas
the reading. For instance, if the read-
ing is taken every 5 minutes, the strcain
should be changed from one to the other,
just as the signal is given.

The temperature of the entering water
is taken by a thermometer at I, and thai
of the discharge at i'. The thermometers
are not directly in contact with Ibe water,
but are inserted in small cups contaicins
oil. The temperature of the room is
taken by the thermometer /,.

21. Pyroinetop. — The temperature

of the exhaust gases must be taken in
order to determine the loss of beat by
way of the exhaust pipe. As these tem-
peratures are too high for the mercary
thermometer, a form of temperature indi-
cator known as a pyrometer is generally
^"^- * used instead. A pyrometer is shown in

Fig. 9. The stem 5 is composed of two tubes made from
metals having different rates of expansion. The meUl^
generally used are copper and iron, the copper tube being

POWER DETERMINATIONS

tCCd inside the Iron tube, or vice versa. The entire s
)m the nnt k should be subject to the temperature i
sired 10 measure,
nee the outside tube is
ated first, the pointer
tquently moves rap-
s' forwards or back-
irds around the dial.
I soon as the stem is
oronghly healed, the

linter will indicate the temperature of the gases. A
pyrometer is also shown at p, Fig. 1.

32. KevoltitioD Counter. — The engineer
should be provided with one of the three forms
of revolution counters shown in Figs. 10, 11,
and 12. The first is a continuous rounUr. the sec-
ond a sfieed indicalor, and tlie third a tachometer.
The arm a of the revolution counter, shown
in Fig. 10. is attached to some reciprocating part
of the engine. The number
of revolutions per minute
may be determined by means
of a watch, and the number
registered at the beginning
and end of a minute noted.
The difference between the
second and the first reading
will be the number of revolu-
tions per minute. The read-
ings of the counter may, instead, be noted
at regular intervals (say of 10 minutes
each), and the nHal number of revolutions
registered during that time divided by the
number of minutes; the result will be the
number of revolutions per minute.

Speed Indicator. — The speetl

I In Pig. 11, registers the total number of

POWER DETERMINATIONS

revolutions. It is aati u
follows: The hand]« h U
held ID ibe hand, and the
soft rubber point /> is thrust
into tile center countersinlt
on Ibe end of the crank-
shaft; the dial d will Uiea
register the number of rev-
olutions. The best wb; to
use this instrument is to
have an assistant obserre
the time. He should sive
the signal "fio" at the be-
giiining of the minttte, asd
the signal "stop" just as the
minute is up. First, set tli«
instrument at zero, or care
fully note the reading of ihe
dial. Then, hold the pointy
opposite the center, and »t
the signal "go" ihrust/inw
the center, holding it tight
enough to prevent it from
slipping. Note the onmber
of revolutions of the dial
and at the signal "stop" l")-
mediately draw the indicalM
away from ihe shaft. Aa
the dial reads to 100, eni
revolution of the dial will
mean lOO revolutiDnsof ll*
crank-shaft. Thus, if *«
dial makes two turns and fl«
pointer slops at 50, the bo"''
ber of revolutions lU 250-

24. Thf Tucliometw-

§25 POWER DETERMINATIONS 19

shown in Fig. 12, is an instrument for measuring the num-
ber of revolutions of a shaft per minute. In principle, it is
a small centrifugal machine, somewhat like the flyball engine
governor. The handle a is held in the hand, and the pointer b
is pressed into the center mark of the shaft. The pointer is
removable and can be placed on the spindles c or </, as shown
by the dotted lines, depending on the speed of the shaft.
The spindle ^ is to be used for speeds less than 500 revolu-
tions per minute; b, for speeds between 500 and 1,000 revolu-
tions per minute; and </, for speeds between 1,000 and 2,000
revolutions per minute. The pointed e is moved around the
dial / by the movement of the weights, according to the speed
at which they are driven. The instruments are usually made
with three scales, and it is necessary to use the scale whose
readings correspond to the spindle used. The axis of the
instrument must be kept parallel with the shaft, and the
spindle used must be in exact line with the axis of the shaft, or
the vibration of the pointer will prevent accurate observation.

DETERMINATION OF TEST RESULTB

METHOD OF MAKING THE TEST

25. The number of assistants required when making a
gas-engine test depends entirely on the number and frequency
of the readings to be taken. One man should watch the
brake and keep the load constant by means of the nut €,
Fig. 1; another should take indicator diagrams and note the
speed; while a third should weigh or measure the water,
note the temperatures, and read the meter. This la«it may
sometimes be divided between two observers, making fnnr
in all. In special cases, one man could take inOi'atnr
diagrams and all readings; but such an arrangement jq not a
good one, because a]] the readings should, if posqjhip, be
taken at the same instant. With two ohsf'rvfT<?. fnOings
should be taken every \h rr/inMf*-q. With thr"** n\ \n\\t
observers, readings may be taken every 5 niinntHfl.

POWER DETERMINATIONS

JSWM JO

)03i oiqno

spnnoj
SnipBaii BIB3S

spnnod

JO sjniBJadcuaj,

IcaiiaaiqHj saajSaQ
JO ajBjBjadniaj,

1 t

1 1

mooa }0 aJiHEiadwai

1 1
1

ainni)^ lad saoisogdz^

1 1

ainoiK Jad saoimioAa^

1 1

ainiJ,

jaqmnu

■"

§26 POWER DETERMINATIONS 21

It is best to make several separate runs, each with a dif-
ferent load on the brake. Twelve or more readings should
be taken with each load, so that, if readings are taken every
5 minutes, the run will last 1 hour, while with a 10-minute
interval, it will last 2 hours. At least three runs should be
made: one at full load, another at half load, and a third at no
load. If the engine is a large one, several runs should be
made at other loads, in order that the economy of the engine
under these various conditions may be ascertained. It is
also advisable to know the maximum load the engine is
capable of carrying. The sensitiveness of the governor
should be determined, where possible, by noting any change
of speed when passing suddenly from full load to no load.
The person in charge should be provided with a whistle.
Thirty seconds before the time for taking the readings, he
should blow two blasts on the whistle, when every observer
should at once go to his post. At the moment for taking
the readings, one blast should be blown, and all readings
must, as far as possible, commence at the signal. No
looker-on should be allowed to interfere with the observers,
and no observer should rely on any one else, particularly an
outsider, to take or record the observations allotted to him.

Before beginning a trial of any kind, the one in charge
should see that a sheet is already prepared for recording the
data observed while the trial is in progress. This sheet —
called the log — should be ruled in horizontal lines and ver-
tical columns, and each column should be headed with an
explanatory phrase or note, showing what particular record
is to be placed in that column. Keeping notes on loose
sheets of paper is bad practice. The accompanying log of
test is a very convenient form for the purpose. There
should be lines enough for recording at least fifteen sets of
observations. Only such observations as are taken during
the test, together with the individual results from each
reading, should be entered on the log.

22 POWER DETERMINATIONS §25

REPORT OF THE TEST

26. After the first test is made and the data are obtained,
the report should be written. A convenient form for the
report is shown on the next pas:e.

The space before the words gas engine should be filled in
with the maker's name, and made by should be followed by
the name of the person or eng^ineering firm that made the
test and is responsible for the accuracy of the results. The
next line should contain the name of the locality where
the test was made, followed by the date.

The report should be made out in duplicate, one copy being
kept by the party that makes the test, and the other \xxag
S^ven to the party for whom the test is made.

27. Clearance. — The first three dimensions in the pre-
ceding^ report blank are obtained by actual measurement, and
need no explanation. The piston displacement is the
product of the area and the stroke of the piston, and is usn-
ally expressed in cubic feet. The clearance is measured
most readily in the following manner: Place the crank on
the inner dead center, and close every opening but one,
which should be on top. Then weigh a bucketful of cold
water, and pour it through a funnel into the compression
space, taking care that none is spilled and that the compres-
sion space is just full and no more. Weigh the water that
remains in the bucket, and subtract this amount from the
first weight. Divide the remainder by 62.5, and the result
will be the clearance, in cubic feet.

Let C = clearance, in cubic feet;

JF= first weight, in pounds;
w = second weight, in pounds.

^''"- ^.= -if

In the larger engines, more than one bucket of water niat
be required, and W should then be taken as the sun: of ±e
weights of the full buckets, and -c the sum of the weights cf
the buckets from which the water has been poured.

REPORT OF TEST

.Gas Engifu

.19

iiONS OF Engine

piston In.

on Sq. in.

troke Ft.

acement . . Cu. ft.

■ • . • • • .V'll. It .

Percent.

Data
al Hr.

X • • • • • • ^^ U • LL«

r Cu*. ft.

o air

r per hour . . . Lb.
r temperature, inlet
r temperature, outlet
r temperature,

.... Degrees, F.
per minute. Average

per hour

per minute. Average

per hour

'e exhaust,

.... Degrees, F.
eroom . Degrees, F.
5ver arm .... Ft.

average . . . .Lb.
t of cubic foot . Lb.

Air — weight of cubic foot . Lb.
Mixture — weight of cubic

foot Lb.

Specific heat, gas

Specific heat, air

Specific heat, mixture

Heat value cu. ft. gas . B. T. U.

Results
Work— ft.-lb. per min . Average
Work— ft. -lb 1 per hour Average

B. H. P Average

Indicated M. E. P. . . Average
Indicated H. P. ... Average

Gas per I. H. P Cu. ft.

Gas per B. H. P Cu. ft.

Mech. eff. B. H. P. -i- I. H. P.
Friction loss I. H. P. - B. H. P.

Heat Per Hour
Supplied by gas . . . B. T. U.
Absorbed by jacket wa-
ter B. T. U.

Exhausted B. T. U.

Absorbed in work . . B. T. U.
Radiation B. T. U.

I Thermal efficiency . . Per cent.
i B. T. U. per I. H. P

24 POWER DETERMINATIONS §25

The percentage of clearance is found by dividins: the clear-
ance by the piston displacement.

Example. — The diameter of an engine cylinder is 10 inches, and the
length of the stroke is 12 inches. A bucket of water is found to weigh
21 pounds, and after filling the compression space the bucket and
remaining water weigh 9.5 pounds. What is: (a) the piston displace-
ment, in cubic feet? {b) the clearance, in cubic feet? {c) the
percentage of clearance?

Solution. — (a) The piston displacement is

area X stroke = .7854 X 10* X 12 = 942.48 cu. In.
= 942.48 -^ 1,728 = .5454+ cu. ft. Ans.
{b) Substituting in the formula,

^ W^w 21-9.5 ,o. ,^ .
^ ' -62:6- = -62X- = -^^ ^^- ^*- ^^^-
(c) Dividing the clearance by the piston displacement, the pe
centage of clearance is

.184 -s- .5454 = .337 or 33.7 per cent. Ans.

28. Volume of Air Used. — The air used per hour m ay
be found, roughly, by deducting the amount of gas used
per explosion from the piston displacement, and multiplying'
this quantity by the number of explosions per hour.
Let " Z' = piston displacement, in cubic feet;
G = cubic feet of gas per explosion;
E = number of explosions per hour;
A = cubic feet of air used per hour.
Then, A^= {P - G) E

Example. — A gas engine has a piston displacement of .5 cubic foot,
and the amount of gas used per explosion is .06 cubic foot; when
exploding 5,000 times per hour, how many cubic feet of air is used
per hour?

Solution. — ^Substituting in the formula,
A = {P - G) E = {.b - .05) 5.000 = .46 X 6,000 = 2,250 cu. ft. Ans.

While this method for finding the^volume of air taken into
the engine is frequently used, it is better to measure the air
by means of a meter. The ratio of the gas to the air is the
ratio of the quantity of gas supplied per hour to the quantity
of air used in the same time. Thus, if 50 cubic feet of gas
is used per hour, and 400 cubic feet of air is used in the satne
time, the ratio of gas to air will be 50 : 400, or 1 : 8.

POWER DETERMINATIONS

'. Ueasurement of Oas Presanre. — Since the pres-
dealt with in gas supply and distribution are quite
, it is the custom to use a unit of measurement of the
ure smaller than the pound per square inch. The
Tsally adopted unit is the pressure per square inch
ed at its base by a column of water 1 inch high,
» is .03617 pound. For the sake of brevity and
:nience, the pressure is not reduced to pounds, but
:pressed by simply stating the height of the water
m, in inches, that the pressure will balance. Thus, if
is a pressure in a gas main sufBcient to
ce a column of water 4i inches high, the y^^y
ure is said to equal, or to be, H inches of ff \

e pressure of gas is measured by means
e same instruments used for air and other
>us fluids. The construction of the instru-
s, however, is varied somewhat for con-
nce in handling.

e most common form of gas-pressure gauge
jwQ in Fig. 13, and is variously known as a
^r gange, a siphon gauge, or a U gauge.
ube a is made of metal, and is provided with
:ket d that will screw on any ordinary gas
e in the place of a burner. The tubes i

are made of glass, and are filled with water
■ the zero of the scale. The scale is grad- piq. u
. in inches and convenient fractions of an

The tube £ is open to the air at the toi». When the
ure is admitted to the tube a, the water will sink in the
6 and will rise in c. The difference in the height of
ater in the two tubes, measured in inches, is the raeas-
f the pressure exerted in inches of water. The depres-
below zero in b should be added to the rise above zero

The fall in one tube will not exactly equal the rise in
ther, unless the tubes are of exactly equal bore. The
ure of the gas is recorded in the log of the test in
s of water.

26 POWER DETERMINATIONS §26

30. Gas Consumption. — Comparisons with other
eng^ines should always be made as nearly as possible
under the same conditions. A gas engine will lose more
heat by radiation in a cold room than in a hot one, and a
considerable diflEerence in gas consumption will be noted
when working with cold or with hot jacket water.

For the comparison of engines working with different kinds
of gas, the heat value of the gas used, in British thermal
units, is a much better basis than the gas consumption; for
a gas engine that will need 20 cubic feet of city gas to
develop 1 horsepower may require 80 cubic feet of producer
gas per horsepower; or the same engine may develop
1 horsepower on 10 or 12 cubic feet of natural gas. If,
however, the gas for the several engines to be tested should
be taken from the same source, a comparison of the gas
consumption per horsepower will be sufficient.

31. Temperatures. — A double purpose is served by
taking the temperature of the water as it enters and as it
leaves the jacket. The first is that the operator is enabled
to regulate the temperature during- the trial; and the second,
that the water acts as a factor in the measurement of the
loss of heat through the jacket. This loss of heat is, of
course, not altogether the fault of the engine itself, for much
depends on the way the flow of water is controlled. The
best makers advise the use of a circulating tank, in which
the water soon reaches the boiling point, and which reduces
to a minimum the amount of heat carried away.

The determination of the exhaust temperature is not so
important in a partial test as the determination of the jacket-
water temperature, but it serves as a check on the indicator
diagram.

The temperature of the room should be subtracted from
the exhaust temperature in calculating the loss through the
exhaust; for the temperature of the gas and air entering the
engine cylinder is approximately the same as that of the room,
and the heat thus carried into the engine must be deducted
from the heat in the exhaust, in order to determine the

§26 POWER DETERMINATIONS 27

amount of heat due to combustion that is lost in the
exhaust.

The temperature of the room will give some idea as to the
loss due to radiation from the engine. An exceedingly high
temperature indicates a large amount of radiation; while a
normal temperature indicates but slight radiation loss. The
specific heats of the gas, the air, and the mixture will be
treated under Heat Losses, while the thermal and mechanical
efficiencies will be taken up in connection with the subject of
efficiency.

32. The readings having all been obtained, it is possible
to trace the heat wastes from calculated results and to dis-
cover the cause of any abnormal loss. Nothing but a
proper interpretation of the indicator diagram will show
faults in valves or igniters. The wastes having been
determined in a general way, the next step to consider is
the calculation of the results from the data obtained. It is
best to have a competent assistant to work up the results
independently, the separate computations acting as a check
on each other. If the two results thus obtained agree, they
may generally be considered correct.

HORSEPOWER CALCUULTIGNS

83. To determine the brake, or delivered, horsepower,
three things must be known: (1) the pressure exerted at
the end of the brake arm; (2) the length of the arm; and
(3) the number of revolutions made by the crank-shaft in
1 minute. The work is dgne on the brake at the rim of the
wheel to which the brake is attached. It is not convenient
to weigh the resistance of the work at the rim of the wheel;
hence, this is done at the end of the brake arm — a distance /
from the center of the shaft. The product of the resistance

•

at the rim of the wheel and the radius of the wheel equals
i times the pressure weighed. The result is that the work
may be considered as being absorbed at a distance / from
the center of the shaft — that is, at the end of the brake arm.

POWER DETERMINATIONS §25

If the brake arm were permitted to move with the pulley
Against a pressure equal to that exerted on the scales, it
would be exerting: that thrust throus^h a distance, per minute,
equal to the distance the end of the arm would traverse in
that time. Now, it is evident that in one revolution the arm
will describe a complete circumference, the lens:th of which
will be equal to 2 ;r /, where / is the length of the lever
in feet; and the total distance traversed in 1 minute will
equal to 2:: In, where n is the number of revolutions mad(
by the crank-shaft in 1 minute. This total distance traversec^^
multiplied by the pressure p gives the number of foot-poun<
of work done in 1 minute; and, since the capacity to ^^
33,000 foot-pounds of work per minute is 1 horsepower, tt:::::::^^
formula for the brake horsepower is

B. H. P. = 1^^ (1)

33,000

Example. — What is the brake horsepower of a gas engine when -^^
brake arm is 3 feet long, the pressure on the scales 25 pounds, and the
revolutions per minute 200?

Solution. — Here, / = 25 pounds, / = 3, and n = 200; hence,
3 jj p _ 2_><3J41^^><3X200 ^ 2 ggg J, p ^^

Since, during any trial in which the same brake is used

throughout, the brake arm does not change, the factor

2;r/
-— V-— is the same for all readings. Ascertain this once

33,000 ^

for all, and call it c. Then simply multiply c by pn io

each separate determination. Suppose, for example, th^
/ = 6 feet; then,

c = -J^ = .001142 (2)

33,000

and B. U,F, = cfin = .001142 pn (3)

It is generally advisable to keep the pressure p cons

during a single run, in which case a new constant ca

computed for each particular run, which will inclu^

Calling this new constant C then

POWER DETERMINATIONS

brake arm will be -

= 18i laches.

In the ordinary form of Prony brake, the leng^th of the
brake arm / is the distance from the center of the crank'
shaft to the point where the knife edge exerts its pressure

on the scale. This distance is denoted by L in Fig. 1.

The lever arm of the strap or rope brake, illustrated in
Fig. 2, is the distance from the center of the shaft to the
center of the strap or rope. For example, if the diameter
of the pulley is 36 inches and the belt is i inch thick, the

For Prony brakes, it is necessary to take into account the
weight of the unbalanced arm. because in high-speed tests a
very small weight may represent a large horsepower. lo
order to do this, the brake is loosened from the flywheel or
pulley, and the arm is allowed to rest on the platform scale
as when making the test. The pressure that the unbalanced
portion of the arm exerts is then weighed, and this weight
must be subtracted from the pressure on the scale when
making a brake test.

34. The Pianlmeter. — To compute the indicated horse-
power from the indicator diagram, the average, or mean,
height of the diagram must be found. The easiest and most
accurate way to do this is to get the area of the diagram by
means of a plan I meter, and to divide this area by the

length of the diagram. A planimeter suitable for this pur-
pose is shown in Fig. 14. It consists of two bars a, b with a
hinged joint c and a roller d. At the end of the bar i is a
weighted point e, which is pressed into the paper just enough
to fix it in one position; the bar b then moves about the
tat*- - 20

J POWER DETERMINATIONS §:

joint e when the planimeter is in use. The point / on tl^^^'
arm a is the tracing point, which is moved over the outlii
of the diag^ram. The roller d has on one edge a flangt
which should roll on a smooth surface; and behind the flanc[*
are graduations, giving readings in square inches and tenth
of a square inch. By means of a vernier g^ the graduation:
on the roller may be read to hundredths of a square inc)
There are a number of types of planimeters in use, difiEerinj
in construction but operating in the same manner. Th
mode of reading may differ considerably, but complel
instructions are always furnished with each instrument.

The planimeter should be used on a smooth level surfac- ^r(
a drawing board covered with a heavy well-sized paper
with bristol board answers very well. The indicator can
is fastened to the board, and the planimeter is set in a1
the position shown in the figure. The starting point
marked with the tracing point /, and the recording rol^ier
adjusted to zero. The outline of the diagram is then ca^re-
fully traced with the point /, being sure to stop exactly^ on
the starting point. The reading taken will be the aresi 0/
the diagram, in square inches.

35. The area is read from the recording wheel and ver-
nier as follows: The circumference of the wheel is divided
into ten equal spaces by long lines that are consecutively
numbered from to 9. Each of these spaces represents an
area of 1 square inch, and is subdivided into ten equal spaces,
each of which represents an area of .1 square inch. Starting
with the zero line of the wheel opposite the zero line of the
vernier, and moving the tracing point once around the dia-
gram, the zero of the vernier will be opposite some point oj
the wheel; if it happens to be directly opposite one of tb
division lines on the wheel, that line gives the exact area
tenths of a square inch. The zero of the vernier, howev
will probably be between two of the division lines on
wheel, in which case write down the inches and tenths
are to the left of the vernier zero, and from the vernier
the nearest hundredth of a square inch as follows: Fin

§25

POWER DETERMINATIONS

I 4

•I

line of the vernier that is exactly opposite one of the lines
on the wheel. The number of spaces on the vernier between
the vernier zero and this line is the number of hundredths
of a square inch to be added to the
inches and tenths read from the wheel.
For example, in Fig. 15, the of the
vernier lies between the lines on the
wheel representing 4.7 and 4.8 square
inches, respectively, showing that the
area is something more than 4.7 square —
inches. Looking along the vernier, it
is seen that there are three spaces be-
tween the vernier zero and the line of
the vernier that coincides with one of the lines on the wheel;
this shows that .03 square inch is to be added to the 4.7 square
inches read from the wheel, making the area 4.73 square
inches, to the nearest hundredth of a square inch.

36. While the form of planimeter shown in Fig. 14 is
very convenient, a much simpler and less expensive instru-
ment, called the hatchet planimeter, shown in Fig. 16,
may be used for measuring the areas of indicator diagrams.

Pio. 15

Pio. 16

This simple instrument, if accurately made and used with
proper care, will give very satisfactory results. It is made
of i-inch steel rod bent at both ends, as shown. The end a
is sharpened for a tracing point, and the other, b, is flattened
like a hatchet. The distance between the tracing point and

POWER DETERMINATIONS

§25

the point at which the curved hatchet end b touches the
paper should be at least twice the length of the indicator
diagram; 10 inches is a desirable length for ordinary use.

r^%trw^eir=^#==;rTfcS?>T»^^^y^*^ ^

«»•-...

«•*..

^J _•- - - • * " •

i # 3 *

Fio. 17

The method of using the hatchet planimeter is shown in
Fig. 17. The indicator card a is fastened to a drawing
board over a piece of smooth heavy paper or bristol board b
that is of sufficient size to furnish the surface for the records

§25 POWER DETERMINATIONS 33

made by the hatchet. The center of gravity c of the dia-
S:ram must be located. This may be done approximately by
inspection, or it may be found quite accurately by cutting:
out the diasfram and balancing it on the point of a pin.
Draw a line A B through the center of gravity parallel to
the atmospheric line /, extending it on the bristol board
beyond the card a. With ^ as a center and the length of the
planimeter as a radius, describe an arc d on the paper b.
Then place the planimeter approximately at right angles to
the atmospheric line /, and, with the tracing point at c^
make the mark 1 on the arc d with the hatchet end; proceed
with the tracing point from c to g, and thence over the outline
of the* diagram, moving clockwise and back to c. During
this movement, the hatchet end is free to move lengthwise
on the paper h as the tracing point moves around the dia-
S^ram. It is best to hold the instrument, just above the
tracing point, between the thumb and forefinger, keeping the
arm of the tracing point vertical and preventing the hatchet
from slipping sidewise. The hatchet will stop at some
point 2 on the arc d. Next revolve the card 180° about the
point ^, as shown by the dotted diagram, until the horizontal
line A B coincides with the extensions A' B' on the paper b.

With the hatchet at 2, move the tracing point from c to /
and around the diagram in a counter-clockwise direction,
returning to c. The hatchet will stop at some point 3 near 1.
Locate the mid-position 4 between 1 and 3 and measure the
distance from 4 to 2, using an accurately graduated scale.
A scale graduated to fiftieths or hundredths of an inch is
most convenient. The area of the diagram, in square inches,
will then equal the distance 4-2 multiplied by the length of
the planimeter.

In order that the measurement may be accurate, it is
necessary that the tracing point and the arc forming the
edge of the hatchet lie in the same plane, and that the dis-
tance between the points / and 2 and the length of the
planimeter are correctly measured. It is best to locate the
actual center of gravity of the diagram, although a small error
in this respect will not cause serious inaccuracy, provided the

POWER DETERMINATIONS

planimeter is set approximately at right ang:les to the
pheric line when starting.

The alinement of the hatchet with the point may be tested!
by drawing a straight line on a horizontal drawing bond, I
and then placing both tracing point and hatchet onthelae
and moving the tracing point along it. If the plane of fix
hatchet is true, the hatchet will follow the line; if not, itiil
run to one side or the other.

37. Mean Effective Pressure, — To determine Ae
mean effective pressure from the indicator diagram, the fint
thing to do is to find the length of the diag:Tam. To do tUs,
draw two lines just touching the diagram at its extreme

Fio. 18

limits, and perpendicular to the atmospheric line, as illus-
trated in Fig. 18. The length will be the horizontal dis-
tance L between these two lines. The area of the diagram
divided by the length gives the mean height, or mean ordi-
nate. This mean ordinate multiplied by the scale of the
indicator spring gives the mean effective pressure, or M. E. P.
Let a = area of diagram, in square inches;
L = length of diagram, in inches;
s = scale of spring.

Then,

M. E. P. = ^

Example. — The area of a certain indicator diagram is 2.17 square
inches, the length is 2.9 inches, and the scale of the indicator spring
is 120; what is the mean effective pressure?

§25

POWER DETERMINATIONS

Solution.-

as 2.17X120

M. E. P. = -^ = -^^

=s 89.8 lb. per sq. in., nearly. Ans.

38. Where a planimeter is not available, the following
method of finding: the mean effective pressure is fairly rapid
and accurate: Draw a tangent to each end of the diagram
perpendicular to the atmospheric line. Then, accurately
divide the horizontal distance between the tangents into ten
or more equal parts (ten or twenty parts are the most con-
venient, but any other number may be used). Indicate, by

Fio. 19

a dot on the card, the center of each division, and through
these dots draw lines parallel to the tangents from the upper
line to the lower line of the card. On a strip of paper, mark
off successively, and with care, the lengths of these lines,
the total length thus representing the sum of all the lines.
Measure this total length, divide by the number of measure-
ments made, and multiply the quotient by the scale of the
spring; the result will be the mean effective pressure.

A convenient method of dividing the length of the diagram
ABt Fig. 19 {a), into the desired number of parts is to draw
the line ^Z, at a small angle to ^^, and then lay off any
convenient length, as A C, the required number of times

POWER DETERMINATIONS

§25

successively, along: A Z, In this case, AB is to be divided
into ten equal parts, hence ^ C is laid off ten times successively
from A to Z. Next connect B to Z, and draw short lines from
the points C, Z?, -£*, etc., parallel to B Z and intersecting A B.
These points of intersection will divide the line A B into the
same number of equal parts into which the line AZis divided.
A more convenient method is to locate the middle points
of the divisions A C, CD, D E, etc. on A Z, and draw lines^
from these middle points parallel to BZ intersecting A B ii^
the middle points of its equal divisions. To find the meari.
effective pressure, erect perpendiculars at the middle points
of these divisions as shown at ab, cd, ef, etc. Find the
average length of these lines by laying them off in succes-
sion on a piece of paper, as shown at a'^', c'^d', e! i\ etc.
to //', Fig. 19 (A). Measure the length from a' to /', and
divide it by the number of parts into which the diagram was
divided. Multiply the quotient by the scale of the spring,
and the result will be the mean effective pressure, in pounds
per square inch.

39. The experimenter will frequently encounter an engine
making a diagram similar to that shown in Fig. 20, with a
loop enclosing the atmospheric line. In such a case, the area

Fio. 20

of the small loop should be subtracted from that of the larger
diagram, before calculating the mean ordinate. The lower
line of this loop represents the pressure in the cylinder as the
charge is drawn into the engine, and the upper line represents

§25 POWER DETERMINATIONS 87

the pressure as the exhaust gases are passing: out. Hence»
the area of the loop represents the work lost in these two
processes.

40. Horsepower Formula. — To compute the indicated
horsepower, the following: formula is used:

I. H. P. = $^
33,000

in which / = mean efiEective pressure, in pounds per square

inch;
/ = length of piston stroke, in feet;
a = area of piston, in square inches;
n = number of explosions per minute.
As in the calculations for the brake horsepower, the dimen-
sions / and a being the same for all calculations, that portion
of the formula which includes these terms may be computed

Example. — In testing a gas engine, it is found that the mean
effective pressure is 75 pounds; the stroke of the piston, 6 inches;
the area of the piston, 16 square inches; and number of explosions
per minute, 70. What is the indicated horsepower?

Solution. — / = 76 lb. per sq. in., / = 6 in. = .5 ft., a = 16 sq.
in., and n =» 70. Then,

^- ^- P- ' ^^^'sSflOO^^^ " ***** ' ^-^^"^ "• ^' ^°^-

41. It is often desired to calculate, approximately, the
maximum horsepower that an engine is or should be capable
of developing, without going to the trouble of taking indi-
cator diagrams. In such a case, the following formula may
be used for four-cycle engines:

I.H.P. =>^^^^ (1)

1,000,000

in which I. H. P. = indicated horsepower;

d — diameter of piston, in inches;

/ =s mean effective pressure, in pounds per

square inch;

r »= number of revolutions per minute;

n = number of cylinders;

/ = length of stroke, in inches.

POWER DETERMINATIONS

Sfj

This formula differs from the one gfiven in Art. 40, anii
as it gives only approximate results, it should not be nsei.
where accuracy is required.

If the engine is of the two-cycle type, the rigrht-hand mem-
ber of formula 1 is multiplied by 2 and the formula becomes

I.H.P. = ^;^^ (2)

600,000 '

Example. — The diameter of the cylinder of a sing^le-cylinder foo^
cycle engine is 6 inches, and the length of the stroke S& 8 incbei
If operated with gasoline at a mean effective pressure of 75 poaadi
per square inch, it makes 180 revolutions per minute; what is tbe
probable indicated horsepower?

Solution.— In this case, ^ = 6X6 = 36, / = 75, / = 8, r = ia
and n = 1. Hence, substituting in formula 1 g^ves

T w T> 36 X 75 X 8 X 180 X 1 o oq w r> , a

I. H. P. = 1 000 000 ~ » °®*^Jy- -Ans-

Table I gives the most suitable compression in absolnte
pressure and the mean effective pressures for engfines usin^
the ordinary gas-engine fuels.

TABIiB I

COMPRESSION AND MEAN EFFECTIVE PRESSURES

Fuel

Compression, in

Pounds per Square Inch

Absolute

Mean Effective Pressure
in Pounds
per Square Inch

Kerosene ....

45 to 70

40 to 80

Gasoline

65 to 95

60 to 100

City gas

45 to 90

45 to 95

Natural gas . . .

115 to 135

70 to 90

Producer g^as . .

90 to 150

60 to 100

Blast-furnace gas

140 to 180

50 to 80

42. The amount of gas used per indicated horsepower
per hour is found by dividing the gas consumed per hour by
the indicated horsepower. The gas per brake horsepower
is found, in a similar manner, by dividing the hourly con-
sumption by the brake horsepower. The loss due to friction
is the difference between the indicated horsepower and the

&26 POWER DETERMINATIONS 39

farake horsepower. Thus, I. H. P. — B. H. P. ■- the friction
loss, in horsepower.

The heat supplied by the gas per hour is the heat value of
1 cubic foot of the gas in British thermal units multiplied by
the number of cubic feet used in 1 hour; for example, if the
heat value is 650 British thermal units per cubic foot and the
hourly gas consumption is 50 cubic feet, the heat supplied to
the engine per hour is 650 X 50 = 32,500 British thermal units.

HEAT LOSSES

43. The following computations of heat wastes are
absolutely necessary only when making a complete heat
analysis of the engine. It is always best that such a test be
made under the direct supervision of a competent engineer.
The following outline for such an analysis is given for the
purpose of explaining the process involved sufficiently to
enable one to determine whether such a test is desirable in
any specific case.

44. The heat absorbed by the water-jacket is equal to
the weight of water passed through the jacket multiplied by
the temperature range; or, in other words, it is the difference
between the temperature of the water when it enters the
water-jacket and that of the water when it leaves the jacket.
For instance, if the temperature of the entering water is 50®
and that of escaping water is 180®, the temperature range is
180® - 50® = 130®. Then, if the weight of the water passing
through the jacket in 1 hour is 100 pounds, the heat carried
away is 100 X 130 = 13,000 British thermal units.

46. To determine the heat carried away by the exhaust
gases, the specific heat, as well as the weight of the gas, in
pounds per cubic foot, must be known. City gas at atmos-
pheric temperature and pressure weighs, approximately,
.078 pound per cubic foot. The specific heat of air is,
approximately, .238 at constant pressure; that of city gas
may usually, without serious error, be taken as .22. For
accurate observations, the specific heat must be ascertained
for the particular kind of gas used. These quantities being

40 POWER DETERMINATIONS §2?

known, the weis^ht and the specific heat of the xnizture, or
chars:e. can be calculated quite readily. The formula for
the heat H per hour carried away by exhaust is

/^ = 5a^^(/» — /,)
in which s = specific heat of mixture;

w = weig^ht of 1 cubic foot of mixture; in pounds;
q = quantity of mixture exhausted per hour, in

cubic feet;
/. = temperature of exhaust ascertained by pyrom-

eter;
/, = temperature of room.
The volume of the mixture passing through the exhaust
is found, approximately, by multiplying the volume displaced
by the piston by the number of explosions.

Example. — The weight of a cubic foot of the exhaust gases of a
certain engine is found to be .068 pound per cubic foot; the specific
heat of the mixture is .23; and the number of cubic feet of gas
exhausted per hour is 90. If the temperature of the room is 80° F.,
what is the quantity of heat carried away by the exhaust when the
temperature shown by the pyrometer is 350® F.?

SoLmoN.— Substituting in the formula, H = 5wq{tx ^ t^^s ^ .23,
a- = .C^v<. V = 30. /, = a30°, and /, = S0=.

H = •::> \ A>>S \ 30 X v350 - S0:> = 126.68 B. T. U. Ans.

4G. The heat absorbed in work is that delivered to the
piston in inuicared horsepower. The mechanical equivalent
of a British thermal unit is 77S foot-pounds; hence, as a
horseivnver is the capacity to do 33,000 foot-pounds of work
per :r.i::u:e, the fomrjla for transforming the indicated horse-
power ir.to British thermal units per hour becomes

,. ^ ,. I. H. P. X 33.000 X 60

. r B. T. U. per hour^ = 2..>45 I. H. P.

KxAMiLr — '♦Vh.it > :::e _uj.-:::yof hejLt absorbed in work per bozr
:t :--.r r. -v.v;.i:c.: hcrs^r^cwer of which is 25?

-• ; — J —

- ^ • = : -4^- V *:^ = 6:^.625. A=$

» * « »• %

emams alter suDtracting the
■-. * redoing three calculations fr-:n:

POWER DETERMINATIONS

INDICATOR DIAGRAMS

The determination of the indicated horsepower is
either the only nor the most important use of the indicator
i^gram; it also serves to show what is taking: place in the
ylinder durins; the time that the diagram is being produced.
^n engineer thoroughly familiar with the operation of the

Fig. 21

^as engine can usually locate a defect much more quickly
from an examination of its diagram than from a tedious
examination of the engine itself.

The diagrams shown in Fig. 21 are, with one exception,
copies of actual diagrams. Diagram A was taken from a

42 POWER DETERMINATIONS §25

Homsby-Akroyd oil eng:ine using: ordinary kerosene oiL
The cycle is the same as that of the Otto g^as eng^ine, and the
diagram is shown as an excellent example of what a g:ood gas-
engine diagram should be. That there is very little resist-
ance in the admission and exhaust passages is shown by the
curved lines that lie close to and just above and below the
atmospheric line xy. These show but little rise or fall of
pressure. The curve above the atmospheric line, if high,
would show resistance in the exhaust passages, and that
below the atmospheric line would show resistance in either
the gas passages, the air passages, or both. Compression
begins at a, and the pressure of the charge is gradually
increased until, just before the piston reaches the end of
the compression stroke, the charge is ignited at b. The
point b of ignition is shown by the sudden change in the
direction of the compression line. The advantag:e gained
by ignition taking place just before the completion of the
compression stroke is shown by the line ec. This line is at
right angles to xy^ proving conclusively that the charge was
fully inflamed before the piston started on its forward stroke.
This is as it should be; that is, the point of maximum pres-
sure is at the beginning of the stroke, just before the piston
starts forwards.

The ragged appearance of the diagram at the beginning of
the forward stroke is not due to any fault of the engine, but
to the vibration of the indicator spring, caused by the rapid
rise of pressure from e to c. The curve would otherwise be
quite regular from c to d, as shown by the dotted lines. The
fall from f to t/ is gradual, and the form of the diagram after
release at d shows a quick-opening exhaust valve and very
little resistance in the exhaust passages.

48, An example of late ignition is shown in diagram B.
lo^nition takes place at a just after the crank has passed the
center. The result is that the initial pressure is much below
what it should be, and the maximum pressure occurs too
late in the stroke. The effect of this derangement is shown
more distinctly in diagram C, where ignition takes place

§26 POWER DETERMINATIONS 43

much later in the stroke. The dotted line shows the shape
of the diagram obtained when ignition takes place at the
proper point, the area abc being the measure of the power
lost. The areas are indicated by the figures on the diagram,
.52 being the area, in square inches, of abcy and 1.10 that
of the actual diagram. This shows that very nearly one-
third of the available power has been lost through faulty
ignition.

49. Bad as late ignition is, too early firing is no better,
because it checks the speed of the engine and causes an
injurious pounding. It may even cause a reversal of the
engine at low speeds and light loads. A diagram illustra-
ting the effect of too early ignition is shown at D. The
excessive back pressure from a io b is very evident. Too
early ignition also gives the cylinder walls a chance to carry
off an excessive amount of heat, owing to the slow speed of
the piston at the end of the stroke. The diagram produced
by such an engine lies inside that obtained when the ignition
is properly timed, as shown by the dotted lines. The loss
of work is shown by the difference in the areas of the two
diagrams^ Fortunately, this is a condition promptly made
evident by the behavior of the engine, and is soon remedied.

60. Care must be taken that the diagrams produced by
badly timed ignition are not confused with those produced
by weaksned mixtures. Examples of the latter are shown in
the indicator diagrams E and F, Fig. 21. In both of these
diagrams, ignition takes place at a, but in diagram F the
maximum pressure is not reached until the piston is at the
middle of its stroke. In E, the maximum pressure occurs a
trifle late, but it should be noted that the line ab is approxi-
mately at right angles to the atmospheric line. The later
occurrence of the maximum pressure is due, not to faulty
timing of the ignition, but to the fact that flame propagation
is slower in weak mixtures, and particularly when the com-
pression pressure is low. The engine from which these
diagrams were taken is governed by throttling both the gas
and the air.

POWER DETERMINATIONS

Stf

51« Diasjam G^ Fig:. 21, indicates very clearly that tbe
exhaust passages are obstructed. The point b should be qd
the atmospheric line xy^ as shown in A at x. Instead, the
line of the diagram does not reach xy until the piston
returns to c. This may be due to a sluggish opening of the
exhaust valve or to constricted exhaust passages. Some
forms of exhaust mufflers will cause the production of such
a diagram.

Several of these defects may occasionally appear on one
diagram. They are all more or less detrimental to the
proper performance of the engine. The remedy will usually
suggest itself in every case. Quite often, the remedy con-
sists in the adjustment of the igniter mechanism or the
proper setting of the valves. Sometimes, however, it will
not be possible to remedy the defect except in a new design.

When desired, the expansion curve may be compared with
a theoretical curve by drawing a curve according to the law
^ z;" == a constant, from a point on the expansion curve where
the combustion is complete. The exponent n should be so
chosen that the resulting curve will represent the average
practice of engines of the type under consideration. In the
absence of a more accurate value, the value of n for adiabatic
expansion, namely, 1.405, is sometimes used. A comparison
of the theoretical with the actual curve may reveal defects in
the expansion curve that could not readily be detected with
the eye. It must not, however, be supposed that the theo-
retical and actual curves should entirely coincide.

52. Fig. 22 shows a diagram taken with an indicator
using a spring that is too weak, and is fitted with a safety

S36 POWER DETERMINATIONS 45

stop, as explained in Art. 13, so that the higher pressures
are not recorded. The sudden drop of the admission line at
the point a shows that the admission valve opens too late.
The horizontal line b^ at the top of the diagram, is caused
by the stop limiting the vertical travel of the pencil when it
rises to this point. The diagram cannot, therefore, be used
lor determining the mean effective pressure.

SXAMPIiES FOR PRACTICB

1. What is the mean effective pressure of an indicator diagram
when the area is 1.88 square inches, the length of the diagram ii
8.2 inches, and the scale of the spring is 90?

Ans. 52.9 lb. per sq. in., nearly

2. A gas engfine makes 5,800 explosions per hour, the piston dis-
placement is .75 cubic foot, and the quantity of gas used per explosion
is .1 cubic foot; what is the approximate number of cubic feet of air
used per hour? Ans. 3,840 cu. ft.

3. The diameter of an engine cylinder is 15 inches, and its stroke ia

2A inches. The clearance is measured by the method of Art. 27.

The weight of the bucket and water before filling the clearance space is

62.5 pounds, and their weight after filling the space is 7.5 pounds.

What is: (a) the piston displacement, in cubic feet? (b) the clearance,

in cnbic feet? (r) the percentage of clearance?

\{a) 2.15 cu. ft., nearly
Ans.^ (bS .72 cu. ft.

I \c) 33.5 per cent., nearly

4. What is the brake horsepower of a gas engine running at
226 revolutions per minute, when the pressure it exerts at the end of
a 3-foot brake arm is 26 pounds? Ans. 3.34 H. P.

5. Find the indicated horsepower of an engine from which the
following results are obtained: mean effective pressure of indicator
card, 96 pounds per square inch; length of stroke, 12 inches; diameter
of piston, 9 inches; number of explosions per minute, 115.

Ans. 21.28 H. P.

6. How much heat is absorbed in work per hour in an engine of
23.5 indicated horsepower? Ans. r>9,807 B. T. U.

7. The exhaust gases of an engine weigh .07.') pound per cubic foot,
the specific heat of the mixture is .225, the number of cubic feet of
gas exhausted per hour is 45, the temperature of the room is 72°, and
the temperature shown by the pyrometer is 375°; what is the quantity
of heat exhausted per hour? Ans. 230 B. T. U., nearly

168—80

46 POWER DETERMINATIONS %2S

8. What is the approximate horsepower of a two-cylinder, four-
cycle, gas engine running at 200 revolutions per minute with a mean
effective pressure of 75 pounds? The diameter of the cylinder is
10 inches and the length of stroke 16 inches. Ans. 48 H. P.

SHOP TESTS

53. When the design of a gas engine has been decided
on, and a number of engines built according to the desig^xii
each one is tested in the shop of the makers before shipment
to the purchaser. In such cases, it is not customary to
make a very exact test, as this is unnecessary for the f^iir-
pose of determining whether the performance of the engine
comes up to the standard. The points to be determined by
the test are: (1) whether the engine runs without undue -fxfc.
tion or overheating, and without leakage at the piston or
valves; (2) whether the valves and igniter are properly timed;
and (3) whether the engine uses more than the guaranteed
quantity of fuel per horsepower per hour, and whether it
comes up to the guaranteed maximum horsepower. In the
following articles is given an outline of the procedure adopted
for tests of this kind by one of the largest manufacturers of
gas engines.

54. Before the engine reaches the testing stand, the
piston has been fitted as accurately to the cylinder as pos-
sible, so that there is little or no possibility of the gases
blowing past the piston. It is, however, almost impossible
to get a new piston so that it will run quite tightly for any
considerable length of time without expanding. This makes
it seize the cylinder in spots causing a knocking sound, which
is due to ,the motion of the connecting-rod on the crank-
pin and wristpin. Of course, this motion is very slight, and
is only the necessary amount of freedom in the bearings;
however, it makes quite a noise. As soon as this knock-
ing develops, the en8:ine is stopped, and the piston taken
out of the cylinder and carefully examined. The high spots,
which are now very apparent, are carefully dressed do\Mi
T/ith a smooth file. This is done very gradually, so as to

S26 POWER DETERMINATIONS 47

avoid taking o£E too much, as to a certain extent the makers
depend for tightness on the piston as well as on the rings.
Generally, it is necessary to remove and dress down the
piston three or four times in this manner before it reaches
that condition where it can be operated continuously under
full load.

55. The indicator is used on every engine, but only for
determining the adjustment of the valves and the timing of
the ignition. When engines are being constantly tested and
the number of indicators available is limited, it is found
impracticable to keep the indicators in such condition that
their results are trustworthy as regards the horsepower;
hence, it is customary to determine the power by means of
the Prony brake.

56. When the engine is to be run with illuminating gas,
the fuel consumption is determined by a meter that registers
to hundredths of a cubic foot. The engine is generally tested
at somewhat above the rated load, though still, perhaps,
below its maximum load. The gas consumed per hundred
charges is measiured and the number of charges* per
minute coimted when the engine is running under the
constant test load, and proper deduction made for charges
missed. Engines built to use gasoline are tested ior
fuel consumption by drawing the gasoline from a gradu-
ated bottle; and, since the consumption is practically constant
under constant load, it is found that a comparatively short
test, using up 1 or 2 gallons of gasoline, according to the
size of the engine, is sufficient.

*The engine built by the company using this outline of tests la
governed on the hit-and-miss principle.

48 POWER DETERMINATIONS |S6

BPPICIBNCT

57. The efficiency of any engine is the ratio of the
work actually performed to the work it is possible to obtain
from the source from which the power is derived. The ratio
of the work actually obtained from the motor to that con-
tained in the source of supply is more often called the total
efficiency; and, in the case of a gas engine, this may be
obtained by dividing the work measured as the brake horse-
power by the total work, or energy, in the gas used, for
the same length of time. A convenient way to do this is to
reduce the brake horsepower to equivalent British thermal
units and divide the result by the British thermal units given
up by the quantity of gas actually used in 1 minute. The
total efficiency is seldom used in actual practice. There are,
however, two other efficiencies that are frequently detennmed,
namely, the thermal efficiency and the mechanical efficiency.

68. Tliermal Efficiency. — The thermal efficiency

is determined by dividing the heat absorbed by the engine
by that supplied by the gas. The result is usually written
as a percentage. In the theoretically perfect engine, the
heat absorbed in work depends directly on the drop in
the absolute temperature of the gas from the explosion
to the exhaust temperature; and the total heat in the gas
depends, in the same way, on the absolute temperature of
the gas at explosion. For this reason, the formula for ther-
mal efficiency is usually written:

in which Et = thermal efficiency;

Tx = absolute temperature of gas at explosion;
7*, = absolute temperature of gas at exhaust.
The thermal efficiency of any gas engine is the total
efficiency of a perfect engine working between the same

§25 POWER DETERMINATIONS 49

initial and final temperatures, because the perfect engine
utilizes all the heat given up by the gas. Hence, the ther-
mal efficiency is sometimes called the efHciauy of the perfect
engine.

Example. — If the initial temperature of a gas at explosion is
2,900'' F. and the exhaust temperature is 1,682*' F., what is the ther-
mal efficiency of the engine?

Solution.— T^ = 2,900° -|- 460° = 3,360°; r. = 1,682° -|- 460°
s 2,142°. Substituting in the foregoing formula, the following equa-
tion is obtained:

Et = ^'^ i J — = .3625, or 36.25 percent. Ans.

59, Mechanical Efficiency. — The delivered, or brake,
horsepower (B. H. P.) is the horsepower delivered by the
engine as measured by the dynamometer or Prony brake.

The mechanical efficiency of an engine is the ratio of
the brake horsepower to the indicated horsepower. It is
usually expressed by the formula

M. E. = ^' ^' ^'
I. H. P.

The difference between the indicated horsepower and the

brake horsepower represents the power required to drive

the engine, and is used to overcome the friction of the

engine, so that, if the engine were running without load,

the power required to run it would represent the friction

load of the engine, or I. H. P. — B. H. P. Hence, it is easy

to see that the lighter the load on an engine, the less the

mechanical efficiency will be.

Example.— (a) What is the friction load of an engine when the
1. H. P. is 25 horsepower and the B. H. P. is 22 horsepower? [fi) What
is the mechanical efficiency?

Solution. —
(a) Friction load = I. H. P. - B. H. P. - 25 - 22 - 3 H. P. Ans.

(b) M. E. = -p-iT" p" ™ OR "■ ^ P®^ cent. Ans.

Average mechanical efficiencies have been found to be
about as given in Table II. An engine using a lean gas (that
is, a gas of poor quality) and high compression will show

POWER DETERMINATIONS

a lower mechanical efficiency than one using: rich
moderate compression.

TABIiE n
▲VERAGB MSCHANICAL EFFICIENCT

and

Size of Engine
Horsepower

Four-Cycle
Engine

Two-Cycle
Engine

4 to 25

25 to 500

SCO upwards

.74 to .80
.79 to .81
.81 to .86

.63 to .70
.64 to .66
.63 to .70

EXAMPUSS FOR PRACTICE

1. The temperature of a gas at explosion, in a gas engine, is
2,740° P., and the temperature of the exhaust is 1,370° P.; what is the
thermal efficiency? Ans. 42.81 per cent.

2. The indicated horsepower of a gas engfine is 237, and the
delivered horsepower is 215; what is its mechanical efficiency?

Ans. 90.7+ per cent

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