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HE THOUGHT IS IN THE QUESTION THE INFORMATION IS INTHE ANSWER
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ILLUSTRATIONS
A PROGRESSIVE COURSE OP STUDV
FOR ENGINEERS, ELECTRICIANS, STUDENTS
AND THOSE DESIRING TO ACQUIRE A
WORKING KNOWLEDGE OF
LRTKiciTv m IT5 mmm>
A PRACnCALTREATlSE
HAWKINS
THEO. AUDEL & CO^
lND STAFF
*7& FIFTH AVB.l«ffi^^^^l*k.
KC 3M^|
COPYRIGHTED, 1917,
BY
THEO. AUDEL & CO,
New York.
Printed in the United Stateg^g^i.^^ by GoOglc
TABLB OP CONTENTS; GUIDE NO. y
TABLE OF CONTENTS
GUIDE NO. 9
ELECTRIC RAILWAYS - - - - - 2,633 w 2,672
Classification of the subject— power systems— direct cur-
rent transmission and distribution; diagram^ use of
boosters ^standard voltages— alternating current trans-
mission, direct current distribution; diagram — sub-
stations — alternating current transmission and
distribution —kind of motor used on single phase systems —
adaptation of single phase system— comparison of the
various systems — map showing route of the Indianapolis
and Louisville railway —interior power station at Scottsburg
(I. & L. R.R.)— power house, car bam, and artificial lake
(I. & L. R.R.) -overbad construction I. & L. 1200 volt
line— current collecting devices— trolley wheel and harp
—section through trolley showing lubricating bushing —
trolley base — overhead trolley system — pan tograph trolley
—surface contact system— third rail system— details
of Manhattan Elevated Railway third rail— details N. Y.
Central inverted third rail— location of third rail relative
to track— underground trolley or conduit system —
Third Ave. R.R., New York, conduit system— comparison
conduit and overhead systems— requirements conduit sys-
tem— motors— d. c. railway motor— principal require-
ments- d. c. split frame motor — G. E. standard box
frame motor— motor classification— forced circulation
method of forced ventilation; with internal air; with ex-
ternal air— natural ventilation — motor suspension—
frame heads of General Electric box type motor— cradle,
nose, yoke, parallel bar or side, and twin motor suspension —
frame heads G. E. split frame piotor— armature construc-
tion G. E. ventilated motor— motor gearing and case—
G. E. split frame motor— various construction details G. E.
conimutating pole motor — motor control systems — classi-
fication— ormnary rheostatic controller— hand control—
detail of G. E. magneticblow out — automatic control — multi-
unit or so called multiple unit control— rheostatic control— [
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TABLE OF CONTENTS; GUIDE NO. 9
ELECTRIC BJahWAYS-CatUinued.
field control— detail of G. E. type K controller constructioa
--series piurallel system of control —mode of transition-
power off method'*- series resistance transition— l>ridge
transition— diagrams of series parallel two and four motor
control— advantage of bridge transition— diagrams of G. E.
type K, two and four motor control connections— wirii^
(fiagram G. E. contactor equipment— Westinghouse K-12
andK-35 controllinjg; connections— alternating current
control systems —single phase motor control by compensa-
tor method— objections to induction regulator method—
Westinghouse auxiliary contactor equipment — three phase
induction motor control— rheostat control applied to
three phase induction motors; type of motor used— kind
of resistance used— Westinghouse imit switch control—
changeable pole method; advantages— cascade operation-
cascade method; single control; parallel single control—
Westinghouse standard reverser- combination of change^
able pole and cascade methods— Westinghouse standard
resistance grids— combined direct current and alter-
nating current control— Westinghouse master controller
—Westinghouse control resister— electric locomotives—
ck^ssification—gesLTless and geared locomotives— G. E. 100
ton locomotive for moderate speed heavy duty service—
side rod drivers— various locomotives— Westinghouse mine
locomotive— the running gear— M. C. B. truck— Brill
maximum traction truck; service suitable for— tandem and
inside hung motors— use of M. C. B. trucks— Westinghouse'
self -lubricating bearing —G. E. storage battery locomotive—
G. E. gas-electric motor car— G. E. gas-electric direct con-
nected set for motor car— brakes— hand brake- diagram
of hand brake system showing stresses— air brakes-
feared brake— "straight air"- diagram of automatic air
rake system— automotic air— car lighting— diagram
showing head lights in series with interior lamps— historical
note— **axle'* lighting of cars— the Stone system— Safety
Lighting Co. axle driven dynamo— method of dynamo sus-
pension in Stone system — McElroy system — S. L. Co. dyna-
mo suspension— S. L. Co. lamp regulator; wiring diagram —
car heating— heater coils and case— location of panel
heater— under seat type heater— construction of Gold two
coil heater unit— points on heaters— regulation of heat—
six heater equipment —track construction for electric
railways — rail bonding — various rail bonds — cable bond —
ribbon bond— typical car tracks with T rails— advantages
of T rails— conduit or underground trolley systems —
section of undergroimd conduit showing hand hole— yoke
TABLE OF CONTENTS; GUIDE NO. 9
ELECTRIC RAILWAYS -C(w/*ntt«i.
construction— third rail construction— cross section of
protected top contact third rail— exposed type— protected
type— details of protected bottom contact third rail—
trolley line construction- bracket catenary construction
—single and double catenary— anchorage for double track
span wire catenary construction— bridge type catenary con-
struction for double track road— Iwigth of hangers— single
catenary curve construction— detail of bracket arm— mes-
senger cable— catenary construction at anchor span— in-
staUation of messenger cable* and trolley wire— trolley
deflector construction at switch —four track double catenary
with bridge supports— signal tLppartLtus— classification^
automatic blodk signal system— non-controlled manually
operated signals— controlled manually operated signals—
automatic operator system— stafif system— tracks used for
block signal circuits— method of applying bond wires-
insulatea rail joint— method of connecting a relay between
insulated joints of track— bell and relay circuits— simple
track circuit signal operated by train in blodc— univei^
train annunciator— three position universal annunciator
diagram— relays— polarized relay- slow release vertical
relay- glass enclosed interlocking relays— Chicago time
relay— signal circuits— frog bonding— electric inter-
locking—interlocking relay— interlocking feature of uni-
versal crossing bell relay— advanced blodc signal— distant
signal and electric circmt— electric interlocking— dispatch-
ers selector system— blocks— road conditions requiring
long blocks— intersection of two double track Hnes— stand-
ard house and distant semaphore signals— three spectacle
automatic double roimd house and distant semaphore
signal— management— scope of the subject— motorman
duties on large roads ; on small roads — experience necessary
— trolley car operation — starting — shuttmg of the circuit —
too much current — violent stops — approaching curves — run-
ning down grades— steep grades— failure of brakes— run-
ning up. heavy grades— starting on heavy up grades— slip-
ping of wheels— use of sand— failure of power— failure to
start— fuse— dead rail— peculiar jumping actioii— bringing
car into house— points relating to controller operation
—controlling manipulation — climbing grades — curves show-
ing advantage of using controller correctly— failure of car
to start — blown fuse — dust on track — Westinghouse mtdti-
unit system — track conditions — condition of brushes — rough
or burned contact fingers— loose or broken cable connec-
tion— burned rheostat— abnormal starting— spaed in-
crease beyond normal— starting with a jerk— flashing— -)qq|^
TABLE OF CONTENTS; GUIDE NO. 9
ELECTRIC RAILWAYS-Continued.
f aulQr operation — Westinghouse interpole motor — motor
troubles — sharp rattling noise — flats — dull thumping noise
—heating, etc.— before starting a train— starting a
train with master control— why controller button is
held down — to start slowly — nmning positions — revers-
ing—train fails to start— failure of power— fault in
master control circuit ; in motor control current — non-release
of brakes— how to detect failure of power— detection of
loose cable jumper— complete wiring diagram of Westing-
house type HL control for four 50 h.p. SX) volt motors—
detection of groimded cable— systematic diagram of West-
inghouse type of HL. control for f oiu: 75 h. p. 500 volt motors
— detection of ground in train cable — poor contact in master
controller— blown master controller fuse— faults in motor
control circuit— electric ship propulsion— inherent defect
of turbine for driving propeller— requirements in ship pro-
pulsion—nature of the turbine— object of electric drive ^
various systems— e/ewen/ary diagram, illustrating the essen-
tials of electric ship propulsion— KohsiTt's alter-cycle con-
trol— Menless system— views of the author.
MOTION PICTURES 2,673 to 2,732
Introduction — optics — light — mirrors — formation of images
on mirrors; why inverted— laws of reflection— spherical
mirrors— focus of curved mirror— multi-images— parabolic "
mirror^ — refraction — laws of refraction — critical angle — *
effect of refraction— total refraction- construction of re-
fracted ray— LENSES— classification— foci in double
. convex lenses— principal fod— conjugate foci— virtual
foci— foci in double concave lenses— experimental de-
termination of the principal focus of lenses —optical center,
seconda^ry axis —formation of images by double convex
lenses— image at twice, more than twice, and less than
twice the focal distance —formation of images by double
concave lenses— effect on rays- the image— formulae
relating to lenses— spherical aberration; oaustics —
effect of large aperture— ill effect of spherical aberration,
how avoided— stops— caustics— chromatic aberration—
white * light — dispersion — achromatic lenses — PRINCI-
PLES OF OPTICAL PROJECTION -relative positions
of the arc, condenser, and objective— lantern slides and
motion picture films used interchangeably —how to select
a lens— the equivalent focus— standard projection lens —
variation of size of image with respect to focal length—
TABLE OF CONTENTS; GUIDE NO. 9^
MOTION FlCTVRES^Continued
precautions in selecting a lens— kind of picture most de-
sirable—two forms of condenser— RULES: Size of image,
focal length, distance from eUde to screen— table
showing size of screen image when moving picture films
are projected— table showing size of screen image when
lantern slides are projected— Motion picture machines—
optical system— intermittent film feed system— persistence
of wision-^^lementary moving picture machine without
case, showing essential parts —opera.tion of elementary
motion picture machine— construction details of film
gate— construction details of intermittent movement
—object of upper and lower feed loops— function of the
film gate— the intermittent movement— Geneva in-
termittent motion— diagram showing progressively the
action of the intermittent movement — threading" a tjrpical
motion picture machine— relative periods of rest and mo-
tion, how varied— illumination for motion picture pro-
jection; the electric arc— kind of current used— adjust-
ment of carbons for direct current -^multi-tip acety-
lene burner— carbon adjustment for direct current
stereopticon arc— the advance displacement— troubles en-
coimtered with alternating cturent arcs— kind of carbon
used for alternating current arcs— angular settings— how
to center the Hght— lamp adjustments— starting, or striking
the arc— characteristics of a long arc— auxiUiary ap-
paratus-alternating current arc setting with cored
carbons— tilted setting for alternating current arc carbons
—90 degree angle arc lamp— Bausch and Lomb diagrams
illustrating results of defective centering of the arc—
various arc lamps — the film — how treated — precautions to
be taken with films— rheostats— transformers— how film
is repaired— the splice— various film perforations— arc
controller— spHce in frame— splice out of frame— Motion
picture cameras— elementary diagram showing essential
parts— operation— how to take motion pictures— various
motion picture cameras— shutter requirements.
GAS ENGINE IGNITION - - - - 2,733 to 2,792
Fundamental electrical principles necessary for an imder-
standing of ignition: electricity— currents— conductors-
resistance — volts — amperes — insulation — short circuit —
metallic, and groimd circuits— direct and alternating cur-
rents—high tension and low tension currents— induced
currents— magnetism— magnetic poles— magnetic fields —
induction —induction coils — methods of nroducing elec-^ OqIc
TABLE OF CONTENTS; GUIDE NO. 9
GAS ENGINE IGNITION— C(m/*ntt«i
trlcity; chemical; mechanical— cells, primary and sec-
ondary — dynamos —magnetos — ignition — various methods
of ignition: naked flame; hot tube; hot ball; electric
make and break; electric jump spark —point of igni*
tion— how much advance desirable— hot tube igniter—
two cyde oil engine with hot ball igniter— electrical igni«
Hon sjTstems^ classification— current for ignition-
primary cells —hydraulic analogies — "dry" cells —points
relating to primary cells— secondary cells— Edison
ceUs— points relating to secondary or storage batteries
—difference between a dynamo and a magneto— mechan-
ical generators— dsmamos -friction drive- how a dy-
namo is generally used— magnetos— classification— in-
ductor magnetos— elementary diagram of double ignition
system with m^;neto and battery ignition— low tension
magnetos— high tension magnetos— elementary dia-
gram — oscillating type — so-called high tension magnetos —
synchronous drive for magnetos— magneto timing
diagrams — low tension ignition — igniters — magnetic
spark plug— elements in a low tension circuit— circuit
<£agrams— how the sjjark is j)roduced in low tension sys-
tems — inductance — primary induction coil — adaptation
of low tension ignition— hammer break igniter— wipe
contact igniter— igniter with inductor magneto— high
tension ignition— wiring diagram— circuits necessary for
the production of the jump spanc — general principles of high
tension ignition— automatic spark advance— high tension
Ignition devices; secondary induction coils; timers
(contact makers, tremblers, contact breakers, interrupters;)
distributers— spark plug— various high tension ignition
83rstems— ignition with pUun coik, with mechanical vibra-
tors, with vibrator coils, with master vibrator— synchron-
ous ignition— magneto ignition— points on magnetos—
dual ignition— double ignition— ignition with special
devices— single break system— coil wiring diagram— igni-
tion troubles; how to cope with— wiring diagrams— how
to adjust a vibrating coil —testing the spanc plug —faults —
comijlete break in the wiring —partial break —primary short
• circuits— secondary short circuits— primary connections— vi-
bration — timers — coils — igniters — wiring diagjrams —spark
plugs— engine misfires and finally stops— engine suddenly
sto^, does not start, runs fitfully— pre-ignition— misfiring
—knocks— loss of power— explosion in the muffler.
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TABLE OP CONTENTS; GUIDE NO. 9
SELF-STARTERS AND LIGHTING
SYSTEMS FOR AUTOMOBILES - 2.793 to 2.814
Classes of starter: mechanical; compressed air; gas;
electric— classes of electric starter— storage battery
required— data on storage battery— state oi cnaige as mea-
sured by hydrometer— different types of storage battery—
choice of voltage— advantage of low voltage— voltage of
units- their general combinations— one unit systems—
wiring diagrams— two unit fl^tems— so-called two unit
system — Leece-Neville two unit systems — Ws^gner dynamo
and cut out— Gray and Davis system— Westinghouse sys-
tem—three unit systems— Disco system— Westinghouse
diagram— Methods of control— thermal method— Ward
Le^iard controller— diagram Rushmore system— discrim-
inating cut out — essentialrequirement in battery chaiging —
Rushmore ballast coil.
ELECTRIC VEHICLES - - - - 2,816 to 2,864
The term electric vehicle— principal tjrpes— electricity as
a motive power— light electric vemdes— Baker electric
roadster— electric trucks for city service— electric
winch on truck— relative merits of gasoline and electric
trucks —plan of electric chassis —gasoline elefctric vehicles
—object of the carbureter— interior Waverly brougham—
elec^c vehicle essentials— various losses— wind pres-
sure— tire friction— losses in the motor— motors for elec-
tric vehicles— Rauch and Lang motor— Waverly motor—
features to be avoided in vemde design— considerations
with respect to friction in bearing— the drive or trans-
mission—herringbone drive— method of attaching—
Waverly double reduction drive— chain drive- objections
—diagram of chain action— cause of climbing the teeth—
double chain drive— advantage of chain drive— two kinds
of chain— snap and rattling— attention required— how to
dean a chain— chain adjustment— chain and sprocket
double reduction gear for heavy trucks— combination
chain and gear drive— worm drive— Baker R & L worm
and gear— worm drive transmission unit— storage battery
for electric vehicles— how weight is reduced— mileage and
battery- points relating to storage batteries —"msmg
diagram of Baker electric — Gould cell — battery capacity — ,
h^gh chai^ging rates — normal charging rates — battery data ^^g l^
TABLB OF CONTENTS; GUIDE NO. 9
ELBOTRIC VERlOLE&r^ConUnue^ ,
^ ( -. -. ^ectrie vehicle oontrpllers^di^graxns— Baker R aiid h
selective dual controller ~ controller diagrams— electric
vehicle circuits— arrangement of circuits with two bat-
teries and two motors— four unit one motor circuit— speed
chang[ing diagrams- feow to operate an electric vehiae—
chargrag an electric in front of city residence— electtiC
vehicle troubles— various faults and remedies.
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ELECTRIC RAILWA YS 2,638
CHAPTER LXXIII
ELECTRIC RAILWAYS
Any system of electric car proptdsion includes besides the
back and rolling stock suitable apparatus: 1, to produce the
current, and 2, to transmit and distribute it to the electric
motors on the cars where it is transformed into mechaiiical
energy to give motion to the car.
The extensive development of the electric railway has given
rise to numerous systems, which may be classified in several
ways, as
1. With respect to the current, as
a. Direct;
b. Alternating;
2. With respect to the method of current generation, as
(steam;
hydraulic;
gas engine.
b. Chemical ^ storage battery.
, 3. With respect to the power system^ as
a. Direct current transmission and distribution;
b. Alternating current transmission, direct current distribution:
c. Alternating current transmission and distribution. ■
2,534 HAWKINS ELECTRICITY
4. With respect to the ciirrent collecting devices, as
a. Trolley;
h. Surface Contact;
c. Third raU;
d* Conduit.
5. With respect to the location of the electrical source, as
a. External \ power station.
J. On the car {^SX^fr^t.
6. With respect to the distribution pressure, as
a. Low tension
"1 volts.
r pressure
\ up to
I 600 volt
, „. - . (pressures
0. Hlgfa tension { above
600 volts.
7. With respect to the service, as
f elevated;
a. City lines \ surface;
[ subway.
b. Interurban or suburban;
c. Long distance lines;
d. Industrial short lines.
Power Systems. — There are three types of motor in use for
electric railways; the direct current motor, the single phase
commutator motor, and the three phase induction motor.
The various transmission and distribution systems which
may be successfully employed are here described and illustrated
in the axjcompanying diagrams. ^^^^^^ ^yGoogle
ELECTRIC RAILWAYS
2.635
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Direct Current Transmission
and Distribution.— This system
is especially well adapted for
densely populated sections as m
large cities. It is not well adapted
to the operation of roads cover-
ing large areas and is becoming
obsolete, owing to the great amount
of feeder copper required to trans-
mit large amounts of energy at 600
volts, which is the standard pres-
sure used.
Ques. Wliy is tlie use of
boosters objectionable on these
lines?
Ans. They add largely to the
fuel expense.
A floating storage battery at ther
end of a long fe^er is sometimes
more expensive to install and oper-"
ate than some of the other systems
later described.
Ques. Wliat are tlie stan-
dard voltages?
Ans. 600, 1,200, 1,600 and
2,400.
Ques. How are the motors,
operated at these various pres*
sur^?
Ans. The motors for the 600
volt system are designed for full
%5i&
HAWKINS ELECTRICITY
3^4j c B **
■.•■:s 4^1.1 11 Ell
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trolley voltage. Pol* the ■
1,200 volt system, both
1,200 volt and 600 volt
xnotors.are used, in the
latter case, the motors
are series connected in
pairs. For the 2,400
volt system 1,200 volt
motors are used, being
series connected in
pairs.
Alternating Current
Transmission, Direct
Current Distribution
— This system is in gen- '
eral use for suburban
roads and the larger
city systems. The ad-
vantages accruing from
the use of both alter-
nating and direct cur-
rent must be evident, .
thus, a large amount of
power caii be transmit-
ted by alternating cur-
rent at high voltage
reducing the cost of =
copper to a minimum,
and by means of , ro-,
tary converters, cOn-;
verted .into dirjeic,t
ELECTRIC RAILWAYS
2,637
■Bills 3
- S? c ?^ s
|l||iB
0^*0 03
~-2
Wt
current of suitable working
voltage for the motors at the
distribution points.
New York City is fed en-
tirely from rotary converters
which receive their power from
alternators and alternating cur-
rent transmission lines at 6,600
and 11,000 volts.
Alternating Current
Transmission and Distri-
bution. — The first practical
application of the alternating
current for both transmission
and distribution involved the
use of the induction motor.
This system required the use
of two trolley wires with the
ground as the third wire of a
three phase distributing sys-
tem. The motors were usually
wound for the trolley voltage
and for operating at half speed
or slower, the current induced
in the secondary of one motor
was fed into the primary of a
second motor, and resistance
was placed in the secondary
circuit of the latter for re-
ducing the speed still . further.
Owing to the compEqated
overhead coistiruction^ due to
2,688
HAWKINS ELECTRICITY
Digitized by ^
ELECTRIC RAILWAYS
2,53d
'^''^ hh'^ £=^.E-ti_> a>i; a? g.^
I
[Oi^.S4j dii a— «v ^^*S S*^ I^
the use of two
trolley wires,
combined
with the fact
that the per-
formance of
the induction
motor does
not give the
bestrestiltsin
tractionwork,
the practical
application of
this system is
confined to a
comparative-
ly few special
cases among
the European
electric rail-
ways.
Amore suc-
cessful alter-
nating cur--
rent system is-
shown by fig,
3,493. As
practically
applied at the
present time
on all instal-
lations in this-
country the
2,54(P
HAWKINS ELECTRICITY
usual trolley voltages are
6,600 and 11,000 volts.*
* 1 S «•?.*-«
Ques. What kind of
motor is used on the
single pliase system?
t^^al^o-^o Ans. The series single
phase motor.
In construction it is very
similar to the ordinary diriect
current motor, except that
the entire field is made of
laminated steel and an aux-
iliary or compensating wind-
ing IS placed in the slots be-
tween the poles to secure
good commutation with al-
ternating currents.- The
motors are usually wound
for 240 volts to which value
the trolley voltage is reduced
by an auto transformer
placed on the car.
As in the case of the
direct current motor, the
speed of the single phase
motor varies with the vol-
tage at its terminals,
therefore, by simply
l^Ms? ,-
a 5 _ o oj-r S#
"3 *'i5 C i 3
K * *: r^ fu s>**
V d s e ^ c g
it " :j ^3 c P «
*= S B £i a =
I
♦NOTE.— For a single pliase system
the alternators are usually wound for
the trolley voltage and feed directly
into the' line without transformation,
thus supplying the whole of Hie road.
Where the len^ of the road exceeds 35
or 40 miles, it is equipped with step
down transformers to lower the trans-
mission voltage to that of the trolley.-.
In cases where it is desirable to fuinish
polyphase current for stationary ix>wer
service, and for the operation of rotary
converters, three phase alternators hav-
ing one phase the full capacity required,.
and utilizing only one c^ the three
phases for railway work. The cost of
Much installation does not differ materi-
jiUy from that of installations having.
tiimp phaM genesi^iB, ..« . • ;^,
ELECTRIC RAILWAYS' 2,541
connecting the motor to different taps on tHe auto^tfansfomi6ts, for
operating at slower speeds, or any voltages -higher than the normal
in an emergency requiring a higher speed,
•— — "-OMB«ctteat Oeapaay's biM, teOpMMlaB- '
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'^ TH^ SHORE UNE ELECTRIC \ RAILWAY
THE CONNECTICUT RAILWAY "17]]^, „., _ \^ „^ ,^ ^
lUCTMO |<.>6C0 VOLT ^\< «• . ■ l aOO VOLT—
Pig. 3.494. — Mj^ of the Shore Line Electric Railway. This line follows the Connecticut
diore of Long Island Sound connecting New Haven with the towns situated along the
lower end of the Connecticut river and passing through the numerous stimmer resorts
which line the coast between Stony creek and old Say brook. The energy for operating
the system is generated at Saybrook by three phase Curtis turbines wound for 11.000
volts. 25 cycles, and is transmitted at the same voltage to two sub-stations, one at the
car bam about a mile distant from the power house and the other at Guilford which
8um)ly 1,200 volts direct current to the entire 52 miles of line. The power house \s
built on ^e banks of the Connecticut River about a mile distant from the town of Say-
brook. The prime movers are Curtis steam turbines of the vertical type. At present,
two of these units are installed, each of 1,500 kw. capacity. They are designed to operate
at a gauge pressure of 160 lb., and with a vacutun of approximately 28^ inches. The
station is designed for an ultimate equipment of four of these turbines. There are two
exciter sets, one a Curtis turbine set and the other a motor generator set. The former,
consisting of a type CC two ix>le. 35 kw. 125 volt dynamo, coupled to a Curtis steam
turbine unit, rtms at 3,600 r.p.m. This exciter set operates non-condensing. The other
set is composed of a CLB sue ix>le. 35 kw^ 125 volt compound wound dynamo direct
connected to a four pole. 50 h.p., 440 volt Form K induction motor. The speed of this
set is 750 r.p.m. Current at 440 volts is supplied to the motor generator sets through
the medium of three type H 20 kv-a.. 11,000/400 volt. 25 cycle, oil cooled transformers.
The switchboard for the i>ower house consists of one three phase induction motor and
transformer panel, two three phase turbine generator ptane-s, two blank panels for future
generators, two three phase outgoing line panels, a swinging bracket provided with S3m-
chronous indicator and voltmeter for the exciter sets, and one two circuit exciter panel.
lAghtning arresters of the electrolytic type are provided to protect the apparatus m the
power house. The boilers are of the water tube type. There are three d25 h.p. boilers
at present and provision is made for a fourth.
Ciomparison of the Various Systems. — For ordinary street
railway service the 600 volt direct current system is almost
universally employed, but for interurban and trunk line service
thei'e is a great difference of opinion as to which of the various
systems is the most economical when all the factors are taken
into account. The factors which must be considered in com-
paring the three systems in any particular case are the following:
; 1. For a given weight and length of trolley or third rail the per cent,
power loss lor a givfen amount of power transmitted varies inversely
as the square of the trolley or third rail voltage. o
%542
HAWKINS ELECTRICITY
Figs. 3,495 and 3,496. — Map showins route of the Indianapolis and Louisville electric raihra7
and connections, and diagram of feeder layout. The lines of this road extend from Sejrmout
to Sellersburg, a little over 41 miles. The company also operates cars between Louisville
and Indiana^lis, a distance of 110 miles. The general scheme of electrification is of special
interest, owmg to its simplicity. The power hpuse is located between Seymour and Seller»-
burg; it feeds the 41 mile line without sub^rtations. The arrangement of the feeders is
shown in fig. 3,496, and is symmetrical in each direction, so that it is only necessary \o
consider a half section. For the first five miles from the power house, the feeder has a capadtjp
of 600,000 cir. mils.: for the next ten miles. 300.000 cir. mils^and after thati211,000 dr.
milt, rar two miles. Thefeederandtrolleyanjoiiied every 1.000 feet. ^
ELECTRIC RAILWAYS
2,543
2. The higher the trolley or third rail voltage the fewer ai« the
number of 8ub>station required for the same effidency of distribution
and weight of conductor.
8. The higjier the trolley or third rail voltage the more costly is
the insulation and supporting structure, and also the greater is the cost
of maintenance of the distribution system.
k 8,497. — ^Interior of power station at Scottsburg (Indianapolis & Louisville line), showine
direct connected two stage units. The two dsmamos as shown are mounted on the extended
•baft of each engine (there being two sets), and the armatures are connected in series to
give 1,200 volts. The fields are connected in series on the ground ddes. The switchboard
consists of two dynamo panels, two feeder panels, and two exciter panels. The switches
an all of the knife pattern. The control is of me automatic Spra^e-(^eneral Electric
parallel unit type. The commutating switch used on these equipments is located on the car
platform beside the master controller for convenience in operation. The operating median-
um of the contactors is similar to those used on standard 600 volt equipments, the only
difference being that additional insulation is used. The protective devices are similar
to those on standard 6(X) volt equipment with the exception of additional blowout capacity
in the main fuse bores. As is usual on 1,200 volt equipments, a dynamotor is provided to
supply 600 volts for the auxiliary circuits, including the secondary control, lighting and
oomi>ressor circuits.
4. Both the first cost and annual expense of the sub-stations are
less for the alternating current systems than for the direct current
systems, since for the former static transformers only are required
whereas for the latter rotary converters must be used. o
2,544
HAWKINS ELECTRICITY
c i- u a fl ji
^■O C S C ^
j&gi5 fl d g
1.^ o o o 5
-.88!
6, The relatively
low power factor of
alternating .current
motors (80 to 90 per
cent.) as well as the
relatively low power
factor of the line
(due to the reac-
tance of the trolley
wire and track re-
turn) gives rise to a
greater power loss in
the alternating cur-
rent distribution sys-
tem for the same
power delivered than
m the case of the
direct current sys-
tem, and this great
loss and lower jxjwer
factor make neces-
sary the emplp3rment
of generating appar-
atus of greater kva.
capacity,
6, The 600 volt
direct current ^motor,
for the same horse
power rating and
speed, costs' less,
weighs less, and oc-
cupies less space than
either type of alter-
nating current motor.
The high voltage
direct current
motors cost more,
weigh more, and oc-
cupy more space
than the 600 volt
type.
7. With the alter-
nating current
motors, transformers
are required on the
locomotives, which
add to the cdst and
weight of the loco-
motive equipment.
ELECTRIC RAILWAYS
2M^
8. The 600 volt direct current motor costs Ifess to maintain and is
liable to fewer operating troubles than any of the other motors.
9. With the commutating tjrpe of alternating current motor the power
lost in the control equipment is practically negligible, since the pres-
sure type of control can be used. For both the direct current motor
and the induction motor a resistance control is necessary, with conse-
quent loss in power.
10. The induction motor is inherentljr a constant speed machine,
and consequently the power input varies directly as the opposing
resistance. The direct current motor and the alternating current
commutator motor are inherently variable speed machines, and the
: Pigs. 3,499 and 3,600. — Overhead construction on the Indianapolis & Louisville 1,200 volt line.
The line throughout is of the single bracket construction on tangents, as shown in fig. 3,499
and of the span type at curves, as in fig. 3 ,500. The poles are spaced 90 ft. apart on tangents
and 60 ft. on curves. A single No. 0000 trolley wire of grooved section is used, and is held
in alignment by 8 in. four screw clamps reinforced with soldered strain guys every half
mile. Lightning arresters are installed every 1,000 ft., and are tapped alternately to the
trolley and feeder. Telephones have been installed throughout the system, and jack boxes
are attached to the poles at all sidings and at half-mile intervals.
power input varies approximately as the square root of the opposing
resistance, the speed at the same time falling ofif.
11. The three phase induction motor, when kept connected elec-
trically to the source of power, automatically operates as an alternator
when the train is going down grade at a speed greater than the syn-
chronous speed of the motor, the motor thus retiiming power to the
line and at the same time acting as a brake preventing any considerable
2,646 HAWKINS ELECTRICITY
increase in speed. Regeneration, as this action is called, can also be
obtained witn the other types of motor, but only at increased expense
for the additional control equipment required.
Current Collecting Devices. — The various electric traction
systems in successful use as distinguished by the mechanical
means provided and special methods adopted for supplying
W
Figs. 8,601 and 8,602.— Trolley wheel and harp. Thd word trolley sigmfies the wheel which Is
■upported at the top of the trolley pole, and which makes rolling contact with the overhead
cooductor. As shown, the trolley consists of a light wheel W, usually of bronze, supported
in a frame or harp H, and revolving freely on a spindle, the latter not shown in the figure.
TTie grooved form given to the wheel not only serves the purpose of seeming additional
contact surface, but prevents the trolley slicing oflf the wire. The spring S, pressing
against the side of the trolley maintains good electrical contact between the wheel ana
insulated wire which passes down through the trolley pole to the car. For city seryfoe
the wheel principally used on the large city systems runs to fairly uniform practice being
4H inches outside diameter, with a H inch V g(roove, IHXl Hm., bronze andjarraphite
bushing, and weighing from 2 to 4 lbs.; 1 H X H m. bushings aie largely employed on city
roads. For interurban service trolleys of from 4 H to 8 M in. outside diameter ara used.
In general the larger the diameter the greater the mileage. Mr. Chas. A. Ingle. Electric
Raflway Journal, 1914, states as follows: "For the past year the Rockford & Interurban
Railway, Rockford. Ills., has been able to average approximately 10,000 miles on its trolley
wheels by getting tne maximum possible wear out of them. We use a 6 in. , 4 lb. wheel with
a Ji in. hollow snaft, for which we pay SI. 05. The new wheels are installed in interurban
service, and as they wear down are transferred to city car until worn out. We had mudi
trouble at first because the hub would become badly worn before the rim. Now when this
occurs we bore out the hub 1^ inch scant and press in a J^ in. inside diameter, IH >?•
outside diameter phosphor bronze bushing, which is swaged at both ends with a tapered pin
QAt in. taper to fit). This makes the buying ti^ht in the wheel and allows it to run freely
on the J4 in. sale. At a cost of 7 cents for lat>or and material we frequently obtain from
3,000 to 4.000 miles additional life from a wheel, and in all cases we obtain the limit of
wear." Other companies report wear from 2,800 miles in interurban service, to 26.000 or
80,000 miles in city service. ^
ELECTRIC RAILWAYS
2,647
current to the motors are, as already mentioned, divided into
four classes:
1. Overhead trolley system;
2. Surface contact system;
3. Third rail system;
4. Underground rail or conduit system.
Pigs . 8 ,603 and 3 ,504 . — Section through trolley showing lubricating bushing , and view of bushing
removed from trolley. Since troUeys revolve at a very high speed, some unusual means of
lubrication must be i)rovided, as shown in fi^. 3,503. The trolley hub is fitted with a brass
bushing, having a spiral groove into which is pressed graphite which acts to fill the pores
of the metal, thus giving a smooth sixrface which reduces the friction. Roller bearing
wheels have been used to a limited extent with considerable success. On some lines a
very long journal is used instead of the usual short brass graphite bushing.
Pig. 3,505. — ^Trolley base. As shown, the pole P terminates in a fork P, attached to a pair of
sector S, S, forming a frame, capable of revolving about a vertical axis V, so as to accom-
modate the pole and trollejr to turns or curves in the track and trolley wire. The spiral
springs G maintain a tension upon these sectors bindixig to force the pole P upward.
This tension has screw adjustment behind the springs. In order to use the trolley when
the direction of the car is reversed, the jpole is pulled down by a rope attached near the
trolley, and then swung around the vertical pivot V, when it is allowed to re-engage with
the wire in the opposite direction. ^
2,848
HAWKINS ELECTRICITY
The Overhead Trolley System. — In this arrangement
which is largely used in towns and cities, the current for the
motors is taken from an overhead wire by means of a **trolley"
with grooved wheels, which is held up against the wire by a
flexible pole. The wires from the contact wheels pass down the
pole to the car controller and thence to the motor, the rettym
circuit usually being through the rails.
Pig. 3,506. — Pantograph trolley; view of motor car showing trolley raised. For use on high
speed roads operating at high pressures a pnetmiatically operated panto^grraph trolley has
been devised which can readily be raised or lowered by the motorman without leaving his
cab. In trains of several motor cars, moreover, the trolleys on the entire train may be
simultaneously controlled from any one point. This trolley is normally held against the
wire by means of a spring, but is lowered and automatically locked down by the application
of compressed air. Application of the air to another point will then unlock the trolley
and allow it to rise.
The Surface Contact System. — This system may be ad-
vantageously used in some industrial works where an overhead
trolley is objectionable, and a third rail is not permissible. The
Westinghouse surface contact system requires no poles or ov^-
head wires and leaves yards and buildings free of all obstructions.
The ciurent is supplied to the motors through contagt buttons
ELECTRIC RAILWAYS
2,549
which are connected to a feeder cable laid along the track,
through electromagnetic switches; the buttons are "dead** except
those directly under the motor cars or locomotives.
The Third Rail Ssrstem. — ^In this system a rail called the
"third rail'* is laid outside the track rails. The current is taken
Figs. 3,507 and 3,508. — Construction details of third rail and contact shoe as used on the
Manhattan Elevated Railway, Ne\<r York City. As shown, the shoe is attached to the coil
spripg seat of the truck, and the shoe proper, which is suspended by two links from the
■yoke, Vhich is in turn bolted to castings on the shoe beam. This type ofshoe has a
tendency to ride on its -lose when the speed is high, and does not permit of adequate pro-
tection of the rail from the weather.
by means of a stiitable contact shoe which slides along the rail,
and the car is controlled by the motorman as in the case of a
tilplley car. This system is extensively used on elevated railways,
subway systems, and on those roads which have a private right
of way* as in the case of electrified steam roads, which operate
h^avy trains at high speed. ^ o
2,660
HAWKINS ELECTRICITY
By means of the third rail it is possible to successfully deliver
to the cars, much heavier currents, and to operate the cars
safely at higher speeds than is possible with the ordinary type of
overhead or underground trolley construction, two important
features which serve to greatly expand the field of application
of the 600 volt direct current motor.
16 P NAILS SPMCCP t'.
HOLU SLANTEP BOTH
UTWALLY ANP L0M6ITUJ?iHAi,LV
BteS. 3,609 to 3.512. — Construction details of Kew York Central Railroad inverted third raiL
As diown, the rail is supported from above every eleven feet by iron brackets, which hold
the insulation blocks by special clamps. These blocks, which are in two pieces, are 6 X ^ ini..
and are interchangeable. Between supporting brackets the upper part of the rail is covered
by wooden sheathing, which is appU^ in three parts and nailed together. At the joints
where the third rail is bonded, and at the feeder taps, the wooden ^eathing is mortised.
This rail is given a little play in the insulators for expansion, except at certain points, where
it is anchored. The rail is of special section and composition and has a conductivity of
about ^ that of copper. The under, or contact surface is placed 2^ inches above the tc^
of the service rail, and its center is 4 ft. 9H ins. from the center line of the service trade,
or 2 ft. 5 ins , from the gauge line of the near rail.
*NOT£. — ^The location of the third rail with reference to the track rails has been different
with each road u^ng it. The Pennsylvania, Long Island, New York Central and Interboiough
Rapid Transit railroads have agreed upon a location which will not interfere with the passage
of any of their rolling stock, either passenger or freight, viz: "The third rail shall be located
outside of and parallel to the track rails so that its center line shall be 27 inches from the track
gauge line and its upper face 3 finches above the top of the track rail." o
ELECTRIC RAILWAYS
2,651
The Underground Trolley or Ciondult System. — Previous
to 1893 many patents were granted on condtiit or other sub-
surface systems of canying the conductors for electric raikoads,
but it was not until after that year that capitalists began to
expend enough money to make a really successfully operating
road. In the conduit system the conductor canying the current
is supported in conduits and the current is taken from it by
means of a trolley which extends from the motor car into the
Pig. 3,513. — Sectional view showixig construction details of conduit system of the Third Ave.
Street Railway, New York City.^ A 4 inch layer of concrete forms a surface on which
to align the iron work, all of whidi is assembled before the main body of concrete is installed.
The track rails and slot rails are supported on iron yokes spaced 3 feet apart and made up
in three pieces, which is a new feature in such work. The three members are a steel I
beam A and two cast iron side pieces B, weighing about 125 pounds each. The yokes rest
on the 4 inch concrete bottom, and the space between the yokes, the center of which space
is the conduit proper, is filled with concrete that must be put in after the iron is in place,
because the throat of the yoke dictates the general shape of the concrete part of ,the
conduit. In order to shape the walls between the yokes, iron linings are used to support the
concrete until it has set. These linings are nmde so that they can be freely drawn through
the slot either way, and they are forced into i>osition by means of a folding form operated
by a lever.^ The track rails are 9 inch grooved girders 107 potmds to the yard, in 60 foot
lengths, laid on pine stringers. This stringer construction is in accordance with the idea
held by many engineers that a rigid supiport for the rails does not afford an easy riding
track.
conduit through a central slot and makes a sliding contact with
the conductor.
This system is used in the streets of large cities where the
use of overhead trolley wires are objectionable, but the cost of
construction is very great. ^^^^, by Google
2,652
HAWKINS ELECTRICITY
Ques. How does the conduit system differ from the
overhead system electrically ?
Ans. The condtiit system has a metallic circuit (two insulated
conductors) while the overhead trolley has a ground return,
that is to say, the track rails which are not insulated from the
ground are used as the return.
Pig. 3,614.-Direct current railway motor, casing closed • as shown, the armature shaft A, projects
through its bearing B, lubricated by the grease box C, and is connected with the. car axle
by gear wheels enclosed in the gear cover D. The gears serve to reduce the speed of the
car, and also to increase the effective pull of the motor. The car axle passes through the
bearing E, lubricated by the grease box P. The motor is supported on the truck by the
lugs G G. The commutator door H gives access to the brushes, while a more complete
inspection of the working parts may be obtained by throwing back the upper half of the
casmg K upon the hinges L L, after unscrewing two bolts, one of which is shown at M.
'The insulated cables shown at N, pass through the casing and supply current to the motor.>
Ques. What are the requirements of a conduit system?
Ans. Perfect drainage; conductor inaccessible from surface
to anything except the contact shoes; good insulation of the
ELECTRIC RAILWA YS
,2,553
conductors; provisions for expansion and contraction; acces-
sibility for repairs.
Motors. — The severe operating conditions of railway service
demand a motor diflfering in many respects from the ordinary
machine. The principal requirements are: 1, that it shall be
dust and water proof because of its exposed location beneath
fflG. 3.515. — Direct current railway motor, casing open; as shown, the essential working jparts
of the motor, consists of an armature A, with a commutator at B; the brushes C C, which
serve to carry the current from the trolley line into and out of the armature; and the four
poles between which the armature rotates. One of the poles is shown in the upper half of
the casing at D, surrounded by the upper field coil E. The pinion P secured to on6 end
of the armature shaft engages with a gear wheel on the car axle, which passes through the
bearings G G, corresi>onding to the bearings designated E in fig. 3,514.
the car; 2, it must be capable of very heavy overloads to secure
quick acceleration at starting; 3, it must be compact because
of the limited space available; 4, large bearings with efficient
self -oiling devices must be provided to secure long oj^erating
3,554
HAWKINS ELECTRICITY
Pig. 3,616. — Direct current split frame motor which allows the lower part to be swunsr down
into a pit for the inspection or renewal of the working parts. The main exciting pole
pieces two of which are shown at AA, are bolted to the frame at an angle of 45 degrecfft to
the horizontal. The conmiutating pole pieces one of which is shown at B, are bolted to the
frame at points midway between the main exciting poles. Commutator doors DD, fitted
with malleable iron covers and gaskets are provided at both ends of tiie motor to i>ermit
of the inspection or ventilation of the working parts under service conditions. They are
inclined at any angle so as to allow of the bru^ holders being readily reached either from
under the car. or through a trap door in the floor of the car. The covers for these openings
are held in place by a readily adjustable cone locking device. Supporting brackets Bfi for
the armature shaft, and brackets P P for the axle bearings are located on the outside top
magnet frame. The linings are held rigidly in the supporting brackets by means of caps
bolted tightly against them. The armature shaft linings consist of bronze sleeves soldered
in place. The layer of babbit metal is so thin that the armature will not rub against the
pole pieces in case it is melted out by overheating. All bearings are designed for oil and
waste lubrication in a manner similar to the standard box journal bearing. The oil wells are
reached through large hand holes protected by strong ,8prings, as shown. Waste oil from
the armature shaft bearings is prevented entering the inside of motor casing or frame
by deflectors which divert the ou into grooves which conduct it away. The main field
coils and the commutating coils are of the type and are wound with either copper wire or
strip as may be necessary. The strip is insulated between turns with asbestos and the
sections are separated from each other by an insulating partition of oiled asbestos and mica.
All coils, whether of wire or strip are ftrst provided with a wrapping of cotton tape and
are thoroughly filled with an insulating compound by the vacuum process. Thev are then
thoroughly insulated with several wrappings of speciall3r prepared tape, and finally given a
wrapping of heavy cotton webbing thoroughly nlled witn japan to protect them against
mechanical injury. The coils are securely clamped to the frame when the pole pieces are
bolted in. The armature core is built up of laminations of soft iron interspaced with venti«
lating ducts. The armature coils are of the formed type, and the windings at both ends are
covered with a strong canvas dressing securely bound in place. The commutator seaments
are made of hard drawn copper insulated throughout with mica. The cone micas are built
up and pressed hard and compact in steam moulds. The mica between the segments Is
made of softer quality, so that it will wear evenly with the copper. The shells and caps are
of cast steel or malleable iron in strong sections which serve to prevent breakage and pre-
serve the proper shape of the commutator. The brush holders, two in number, are maoe of
cast bronze and hold from two to four carbon brushes each, according to the size of the
motcr. The brushes slide in finished ways, and are pressed against the commutator by
ELECTRIC RAILWAYS
2,555
periods without attention. The first requirement calls for
enclosed construction, thus instead of a frame as in the ordinary
motor, this number takes the form of a case or the "iron clad*'
construction.
To permit the heavy overloads necessary at starting as well
as the heavy duty running conditions, the proportion of parts
comprising the electrical circuits, as inductors, field coils,
Fig. 3,617. — General Electric standard box frame motor. In this tyi>e the magnet frame i»
one piece of cast steel, and. as shown, is approximately octagonal in shape. The frame is
provided with bored openings at each end, through which the armature, pole pieces, and
field coils can be inserted or removed through the pinion end opening. Bails are cast on
tiie frame at convenient points to facilitate handling. The opemng through the frame over
the commutator is large and inclined at an angle to allow easy access to the commutator
and brush holders. Hand hole openings are located at points most convenient for the
inspection of the interior of the motor. Drain holes are drilled in the lower side of the
motor frame. The axle caps (which are inclined at an angle of approximately 60 degrees
to the horizontal) are tongued and bolted to machined surfaces on tne magnet frame.
Pig. 3,516. — Description continued,
independent fingers, which exert a uniform pressure throughout the working range of the
bruwes. A "pig tail" or shunt is inserted between the fingers and the hrusn holder body
to prevent cxirrent passing through the n>ring which actuates the fingers, or througn
fhe pivoting pins. Tne brush holders are adjustable in position to allow for wear of the
commutator, and can be readiljr removed through the commutator door. The three point
suspension is a salient feature in the designing of these motors. In the box frame type
fhe front of the frame or casing is provided with a lug which rests on a brcicket secured to
tiie truck transom. The motor is Kept from rising by means of a forged strap bolted over
fhe top of the lug. When the truck is out from under the body of the car, the motors can be
mounted on or taken off the truck from above, no pit being required. In the split frame
motors, lugs are cast on the upper half of the frame to which a suspension bar is bolted.
2,656
HAWKINS ELECTRICITY
commutation segments, brushes, must be increased to proper size
for the heavy current. A similar increase of dimension bf the
bearings, shaft, pinion, etc., must be made to secure proper work-
ing stresses. These requirements together with the fact that
the construction must be compact, result in a design of motor
considerably different in appearance from the ordinary motor
for stationary service.
Fic. 3,518. — Method of forced ventilation with internal air. In this arrangement there are no
ventilation openings to the outside air, the air being circulated internally in the motor, as
shown.
Ques. Name an important provision that should be
made in railway motor design.
Ans. Some means of ventilation should be provided espe-
cially for motors to be operated in warm climates.
Ques. Name two methods of ventilation.
Ans. Natural, and forced.
Natural Ventilation. — ^This may be secured either
\ternal circulation or circulation of outside air.
by
In the first
o
ELECTRIC RAILWAYS
2.667
mentioned method, the heat is distributed by keeping the
warm air stirred up through the ducts.
The method of circulating the external air through the in-
terior of the casing may be used in warm weather but with
caution when there is much dust in the air.
Forced Circulation. — This may be secured by a fan located
either within or outside the motor. The fan is usually
Fig. 3,519. — Method of forced ventilation with external air. In construction, the fan is cast
int^ral with the pinion end armature head, which draws air in through a screened inlet.
in operation, the air passes around field coils, over and through the commutator and
armi^ture coil, carrying uie heat from the interior, and thus increasing the service capacity
of the motor.
mounted on the armature shaft at the pinion end and inside
the casing. This fan drives air out of the motor through open-
ings in the pinion end of the motor which is replaced by
external air entering through a screened opening over the
armature and field coils, under and through the commutator
and then through longitudinal ducts in the armature core.
2,658 HAWKINS ELECTRICITY
Motor Glasslficatioii. — ^There are several types of moUx
used for railway service, and these may be classified
1. With respect to the kind of current used, as
a. Direct;
b. Altematbg {^^^'^
2. With respect to the pressure of the current, as
[fiO volts
a. Low pressure \ \o
■ - 1 220 volts;
[250 volts
bi Medium pressure 1 ^ to
, *^ 1 650* volts;
[600 volts
c. High pressure \ to
^^*^ I 2400 volts.
3. With respect to winding and operating principle, as
a. Series direct current;
b. Series single phase;
c. Induction, three phase.
4. With respect to the method of ventilation, as
a. Natural ventilation {S^l^fe;
ft. Forced ventilation {S^f^'^'
6. With respect to the transmission, as
a. Direct drive;
b. Geared drive.
The various types of motor and their principles have already been
treated at such length (see Guide No. 2 loi direct current motors, and
Guide No. 6 for alternating current motors) that it is not necessary to
add anything here, save to treat of the peculiarity of CQnstructu>n«
behavior, m^hods of placement, etc o
ELECTRIC RAILWAYS
2,559
Motor Suspension. — ^An important point in railway motor
design is the method, of suspending the motor and usually much
care is devoted to the selection of the best arrangement.
Usually the motor is constructed with a set of bearing on one
side of the frame, in which bearings the axle of the car wheels
rotate. Moimted up<in this axle is a large gear which meshes
with the pinion gear on the end of the armature shaft, the gears
being protected from dust, etc., by a casing. The side of the
motor opposite to that containing the car axle is usually fastened
Pigs. 8,A20 to 3,623.— Frame heads for General Electric box type motor.
to a bar, which in turn is motmted upon springs connecting it
to the car truck.
There are ntunerous forms of suspension, and these may be
classed as
1. Cradle suspension;
2. Nose suspension;
3. Yoke suspension;
4. Parallel bar or side suspension;
5. Twin motor suspension. Digitized by Google
2,560
HAWKINS ELECTRICITY
Ques. Describe the cradle suspension.
Ans. It consists of a U shaped bar fastened to the truck at
the middle of the U, as shown in fig. 3,525.
PzGS. 3,524 to 3,526. — ^Various motor suspensions. Pig. 3,524, nose suspensionr fig. 8,825^
cradle suspension; fig. 3,526 i>arallel bar suspension. . . ^
ELECTRIC RAILWAYS 2,561
The caradle suspension is intended to relieve the bearings of the weight
of the motor. The total weight of the motor is. hung by lugs on eimer
side from a longitudinal horizontal bar which at the back end is spring
supported from lugs on the arm which carries the axle bearing and at
the front end by a cross and beam truck frame. This tjrpe of suspension
is now semi-obsolete.
Ques. Describe the nose suspension.
Ans. This method consists of casting a projection or **nose"
on the motor frame, and fastening it to the motor truck by means
of a heavy link.
Figs. 3,527 and 3,528. — Frame heads for General Electric split frame motor. These heads are
of the solid type and special provision is made to secure grood lubrication.
The object of nose suspension is to distribute the weight of the
motor between the car axle and the truck. This is the most used
method. In operation the springs in the nose suspension lessen shocks
during starting or sudden changes of torque, about 60 per cent, of the
weight of the motor being carried directly on the axles without spring
support.
Ques. Describe yoke suspension.
Ans. In this method a cross bar is rigidly bolted on to seats
cast on the motor casing, and the ends of these bars are spring
supported on the truck frame.
Ques. Describe parallel bar or side suspension.
Ans. This consists of two parallel bars fastened to the car
truck supporting the motor on springs at its center of gravity.
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HAWKINS ELECTRICITY
^ o ^ ^ ^ ^^T
Digitized by VjOOQ IC
ELECTRIC RAILWAYS
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Ques. Describe twin motor suspension.
Ans. In this arrangement two motors of equal capacity are
mounted above each axle. Each motor is provided with a pinion
and the two pinions of the pair of motor mesh with a single gear
which is mounted on a quill surrounding the driving axle.
By this method, two i^mall motors, each having twice the rotative
•peed of one large motor, may be used. Since each little motor is about
FM38<i 8,634 to 3,537. — ^Armature construction of General Electric ventilated railwE3r znotor^
The core is built up of laminations mounted upon and keyed to the armature shaft. The
armature is so constructed that the shaft can be removed without disturbing the windings
or connections to the commutator. The laminations are punched and assembled with the
boles in alignment so as to provide longitudinal holes throus^ the core structure. The
pinion end thrust collar has two oil throws, and the commutator end thrust collar, three, so
designed as to prevent oil reaching the interior of the motor.
9ta8. 8,688 to 8,640.— Railway motor gearing and case. Fig. 3,538 large gear, which is attached
to the car wheel axle; fig, 3.639 pinion, which meshes with the large gear, and which is
attached to one rad of the motor shaft; 8,540 gear case to protect large gear and pinion
from dust, etc - (^
2,564
HAWKINS ELECTRICITY
half the diameter of one motor of capacity equivalent to that of the
pair, the pair may be mounted on a lighter frame and the weight of
the end housings may be reduced. The width of the gear required on
each axle is but half that required with one large motor of equivalent
capacity. Hence the wek^t of the gear is reduced and a larger and
more economical design ofmotor is made possible.
Pig. 3,641.— General Electric split frame motor. The frame is split horixontally with flM
suspension on the top half. The bottom half is arranged to drop to pennit inq)ection
of the interior of the motor from a pit. The armdture bearing trame heads are of the
solid head type giving the same qualities of oil lubrication as are obtained in the standard
box frame motors. The upper and lower halves of the frame are held together by four
bolts and two hinge bolts, and each frame head is firmly secured to the upper frame by
bolts which are easily accessible from a pit. By removing these bolts (excepting the
hinge bolts) and the lower half of the gear case, the armature can be removed. The upper
and lower magnet frames are provided with machined surfaces fitting closely around the
bearing heads, which act as keys in sectuing the alignment of the upper and lower halves
of the motor frame. The axle bearing caps are bolted to planed surfaces on the top half
of the frame and all the bolts are accessible from a pit. The armature is so constructed
that the shaft can be removed without disturbing the windings or connections.
Figs. 3,542 to 3,547. — Various construction details of General Electric commutating pole
railway motor, fig. 3,542, exciting field coil and supports; figs. 3,543 to 3,545 details cl com-
mutatmg field cml and supports; fig. 3,546, bnish holders; fig. 3,547, malleable iron gear
ELECTRIC RAILWAYS
2,565
Pic. 3,548. — Ordinary rheostetic controller, designed to control one or more motors by means
of resistance only. As shown, it consists of d switch cylinder A, carrymg nine msulatmg
supports upon which are mounted nine metallic conducting s^sments B, B, B. These
segments differ in length and position, and when the cylinder is turned by means of the
handle C, they come in contact at different times with the nine fixed contact spring
D, D, D, which effect the changes in the connection by which more or less resistance is
brought into or out of the motor circuit, thereby producing a change in the speed of the car.
It is evident that after contact has been made between the motor and the trolley, an electnc
arc, very destructive to the breaking contact within the controller would be establiaAied
unless some means were provided for breaking the arc at the instant of its formation.
This is accomplished by means of a magnetic blow out device consisting of the magnet E
and its pole piece, carrying the i>olar ndges G, G, G, which rest close to the contact
springs D, D, D, when the pole pieces are placed in normal position. In operation, the
current passing through the motor passes through the coils of the magnet E, and converts
its core mto an electromagnet whicn produces a powerful magnetic fltix around the contact
surfaces of the ^rings D, D, D. At the instant the circuit is broken either in changing
connections or when the current is entirely shut off, the irresistable influence of this pjower-
ful magnetic flux prevents the severe sparking which would naturally occur otherwise by
blowing out the arcs as soon as they are formed. The reversing cylinder H, carries four
conducting segments K, and a corresponding number of contact spnng L. By moving the
handle M through an arc of about 60 degrees, the segments in contact with tiie springs L,
can be changed and the direction of the current through the armature of the motor reversed,
thereby causing it to rotate in the opposite direction and back the car. As the reversing
operation cannot be safely accomplished while the motor is running, the handles C and M
are made interlocking so that the latter cannot be moved unless the former be in the "off
position." In other words the current must first be shut off before the direction of the car
can be reversed. This prevents any arcing on the contacts of the reversing cvlinder. The
proper operation of a controller requires that all the successive contacts be made and
none omitted. This is insured by the action of the star wheel located at N. Rheostatic
controllers may be used tor single motor railway equipments, single or double motor mining
equipments, and for crane, eto. It is important to have a full knowledge of all the require-
ments of any particular service before selecting the controller. For service requiring fre-
quent motor reversals, a controller witii a single handle, with the motor circuits so arranged
as to perform the ftmction of the reverser, is found more convenient than a controller vritn a
separate reversing handle. Controllers with single handles are usually employed to operate
travelling cranes, turn tables, stationary and portable hoists, etc., while those having two
handles are generally used with street railway and mining equipments. ^
2,566
HAWKINS ELECTRICITY
Motor Control Systems. — ^In the case of nearly all railway
motors of both the direct current and alternating current types,
the speed of the motor varies with the voltage impressed upon
its terminals. In other words, by increasing or decreasing the
Pics. 3.640 and 3.560.— General Electric aeries parallel controller. In thia type, of which tli«e«re
several forms, the power circuits are not broken during transition from series to parallel
connections. The series parallel controller, as is well known, is used to control two motois,
or two x>airsof motor, and serves to connect these motors in series or in parallel relatioii.
By means of these connections a car may be run economically at a medium speed, as well
as at full speed, and can be accelerated to full speed more efficientljr than is possible with a
simple rheostatic controller. Hence, the practically universal adoption of the senes parallel
controller in railway service. The older forms of K controller were designed for operation
on a normal line pressure of aimroximately 600 volts. With the advent of the oommutattng
pole railway motor, the use ofhigher operating pressures. 600 to 660 volts, became possible
and is now common practice, eroecially on interurban lines. To successfully operate on
these hiilier voltages, individual blow outs and other features were introdttoed.
ELECTRIC RAILWAYS
2,567
voltage applied to the tenninals of a motor its speed may be
correspondingly increased or decreased.
It is evident that one of the principal requirements in the
operation of electric cars is that they should not only be capable
of being started, run up to full speed, slowed down and stopped
gradually, but should also be capable of being stopped suddenly
and their direction of motion reversed in emergency.
These various speed requirements give rise to several control
sjrstems, and the apparatus employed to effect the proper
sequence of connection corresponding to the system of control
adopted is known as a controller/ A comprehensive classi-
fication would divide the various S3rstems
1. With respect to the method of operation, as
a. Hand control; '
b. Automatic control;
c. Master controL
2. With respect to t^e current, as
a. Direct;
h. Alternating.
. f
8. With respect to character and sequence of connectionSi at
a. Direct current
rheostatic;
field;
series parallel;
multi-umt (master control).
f rheostatic;
single phase
6. Alternating current
three phase
compensator;
induction regulator;
rheostatic;
changeable pole;
***^® 1 pan^
combined changeable
pole and casca de.
4» With respect to the method of transition, as
o. With power off;
Ik With series reais t anoe; DigtizeidbyGoOQie
e. Bridge. ^
2,568
HAWKINS ELECTRICITY
The various systems in general use are illustrated in the
accompanying cuts.
Ques. Define hand control.
Ans. In this system the motorman, by moving the con-
troUer handle, can vary the current value without any time
limit device.
Fto. 3j551. — Detail of General Electric type K magnetic blow out showina main finger «nd
wire clamps. The figore shows the construction of blow outs used in forms K-34, K<r35,
K-36 and K-44 controller. Each finger is supplied with a separate magnetic blow out,
consisting of a complete magnetic circuit, blow out coils and arc deflecting diutes. In
tliis illustration one of the iron plates forming part of the magnetic circuit is removed to
•how the finger and blow out coil. The current entering at the clamp terminal passes
through the blowout coil, through the finger to the segment, generating a strong magnetic
field across the space between the arc deflector plates, so that when the circuit is broken
the arc is blown m an outward direction, away from the cylinder. In order to extend the
pole pieces to a point where arcing occurs, between the finger and segment, iron plates
are imbedded in the insulation of the arc chutes. The arc diutes are made of a special
moulded insulation compound, which does not carbonize tmder the influence of an arc.
Ample space is provided in tnese chutes for the expansion of the arc when breaking a
circuit. As the arc is projected away from the cylinder, the danger from short circuiting,
f^iich occurred with the older form of blow out, has been eliminated. In the older con-
trollers, the magnetic blowout is composed of one magnetic field, extending the full length
of the cylinder, and produced by a single coil. The effect of this field is to extinguish the
arcs bv blowing th^ either up or down against the deflector plates, and not directly
away from the cylinder.
Ques. Define automatic control.
Ada. This system includes certain automatic devices which
ELECTRIC RAILWJlfYS
2,569
prevent the motorman applying to the motors a current greater
than a predetermined value.
Thus, the motor starts with a proper cturent and as soon as the cur-
rent has decreased to a specified value, the connections are automatically
changed so that the rate of acceleration and the current are kept prac-
tically tmiform throughout the period of control.
Ques. Define master or multi-unit control.
Ans. This system, ill advisedly called multiple unit control,
is one in which the motors on each car of a train of several cars
are controlled from one master controller.
Fto. 8,552. — ^Detail of General Electric type K magnetic blow out showing pole piece, Mg-
ment and removable tip.
The principal object of multi-imit control is in service reciuiring that
cars be operated singly or several coupled together in a train and oper-
ated simultaneously, the connection being so arranged, when several
cars are coupled together, that the motors on aU of the cars may be
controlled from either end of any car by a single operator.
Que8. Describe rheostatic control.
Ans. This consists of progressively cutting out sections of
a resistance connected in series with the motor. ^ ,
2,670
HAlfklNS ELECTRICITY
An ordinary rheostat is used and the method is confined to single
motor installations as in mining or other small industrial locomotives.
Que8. Describe field control.
Ans. This method consists in varying the intensity of the
motor field magnets, by dividing the coils into two sections and
arranging the controller to give a proper sequence of connection.
Ftos. 3,553 and 3,554.— Details of General Electric type K controller construction. Pib,
method of fastening tips to Mgmeats; fig. 8.664, dJtoU of cylinder casting assembly
ELECTRIC RAILWAYS 2,671
Thus, when the two sections of the motor field winding are connected
in series, a strong field is obtained, and therefore slow speed. By
arranging the second step of the controller to cut out one field section
the speed is increased. The complete sequence of connection gives two
series running positions and two parallel miming positions, thus making
four running positions.
Que8. What control system is very largely used?
Ans The series parallel.
Ques. Describe this method.
Ans. This method is used with two or four motcw equip-
ments. The sequence of connection for a two motor car dtuing
the control period is as follows: 1, both motors connected in
series with control resistance, 2, control resistance progressively
teduced, 3, control resistance again put in circuit in series with
parallel coimection of motors, 4, control resistance progressively
reduced, 6, both motors in parallel with control, no resistance.
Ques. What feature of series parallel control divides
this method into several types?
Ans. The mode of transition.
Ques. Describe the power off method of transition.
Ans. In this method the controller is so arranged that the
power is cut off from both motors in changing the motor con-
nections from series to parallel.
This was f (Mtnerly used for large size motors and locomotives but
is not used much at present.
Ques. Explain series resistance transition.
Ans. During the transition from series to parallel, a re-
sistance is placed in series with one motor and the other motor
is first short circuited, then disconnected from the main circuit,
and finally placed in parallel with the other motor.
This method is in general v^ iin equipm,ents of small motors with
thesocaUedtypeK^controlier.' V ' .
2,672 HAWKINS ELECTRICITY
Ques. What is bridge transition?
Ans. This method consists in grouping the motors and their
resistances like the arms of a Christie, or erroneously called
Wheatstone bridge,* so that after the two motors are in full
TROLLEY Wl RE <500 VOLTS)
z
MOTOR I MOTOR 2
( 250 VOLTS) (250V0LT5)
RESISTAHCE ARMATURE FIELD ARMATURE FIELD
(ALL OUT)
(500 VOLTS)
z
MOTOR I
(500V0LXS )
HOA/VWf OVWVV
RESISI^IICE =: MOTOR 2
<ALLOUT) (500 VOLTS)
Figs. 3,556 and 3,556. — Diagrams of series i>arallel two motor control. Pig, 3,555, i
ntnnizig position, all resistance cut out; ng. 3,556, parallel running position, aU res«itance
cut out. When the controller handle is in the series running position, fig. 3,555, the motors
are in series, and with a 500 v( It troUev circuit, each motor therefore operates at 250 volts
In fig. 3,556, both motctrs are in parallel under the full 500 volt pressure. The two positives
here diown are with resistance all out. A number of intermediate i>ositions may be obtained
in both series and parallel positions by progressively cutting out a series resistance. When
a rheostatic controller is used with, for example, a two motor equipment, the motors are
connected permanently in parallel, and the current divides into two branches, one of whcb
passes through each motor, before they become joined again in a single circuit, passing to
the ground. Under this condition the amount oi current required by each motor is double
that which would be required by one of the motors to move its share of the load. As all
this current has to flow through the resistance of the rheostat, the volts dropped in the
rheostat constitute a loss, since they do no work, but are wasted in the form of| heat.
Series parallel operation prevents some of this loss as the motors are in series at starting
and the same current which starts one motor passes through and starts the other, therebv
taldxig only one-half as much current from the line as when a rheostatic controller is used.
The final or full speed connections are the same in both methods, the motors operatini[ in
parallel at the f ulltrolley line voltag^ with all ivsistance cut out of the circuit. ^ In selecting
a series parallel controller, as in the case of any other similar apparatus, it is important to
consider the nature of the circuit, whether wholly metallic or ground return, the number of
motor per equipment, and the capacity of each, and the character of the service required, of
the controller, whether for simple series parallel operation, series parallel control with
emergency electric bn^, or series parallel control with electric brake for regular operation.
The controller should not only be of sufficient capacity, but should be arranged for the
number of motor operated. For example: a series parallel controller designed for two
100 H. P. motors is not suitable for an equipment of focff 60 H« P. motors, as the reversifig
ewitch must have separate connections for each motor. Furthermore, controllers of either
the rheostatic or series parallel type for operation with electric brakes for either tmnfffiocf
or regular service should have the necsswiy contacts and eooaections for the operatum of
tbebrakes.
o
ELECTRIC RAILWAYS
2,573
series position, the resistances may be placed in circuit again
in parallel with the motors without opening the circuit. The
two motors are then connected in parallel with each other and
each in series with its own resistance.
Ques* What is the advantage of bridge transition?
Ans. There is no noticeable jerk as both motors are in
«A^o . ( 250 VOLTS ) „„^^
MOTOR I , . * . MOTOR
(250 VOLTS)
RESISTAMCE
< ALL OUT)
MOTOR
3
Ut* ARrtXTURE
' [ L FIELD
MOTOft
(250 VOLTS) ^
(250 VOLTS)
(500 VOLTS)
(500 VOLTS)
'--I M I 1 1 - J J fSOO VOLTS) ♦ I
MOTOR
J^P^WW
(500 VOLTS)
( C50QVOLT S>|
tow
MOTOR 4
Pigs. 3,557 and 3,558. — Diagrams of series parallel four motor control. Pig. 3,557 series runfliasr
position, all resistance cut out; fig. 3,558, i>arallel i
1 running position, all resistance cut out.
Operation throughout control period and it is not necessary to
Open the circuit which would cause flashing at the switches.
This method is used mostly on multi-uait control equipments,
particularLy for large size units.
«NOTB.— See note pass 2,239.
Digitized
by Google
2,574
HAWKINS ELECTRICITY
Digitized
by Google
ELECTRIC RAILWAYS
2.675
Ques. How is series parallel control applied to four
motor equipments?
Ans. By connecting the motors in parallel in pairs and
treating each pair as a unit.
1^ Z7^
7bl^/?tsancf/i(npl
/fsfcf^a?^/ W7r/flp/nffStyftch\
/n Controller
Corrtactor^
fuse Sox \
Fic. 8,681. — Wiriag diagram of General Electric oontactor equipment, dwrignad to eUmina^
all destructive ardnff form the car platform, by opening and clodng the main i>ower drcuit
with contactors located underneath the car bodv. Two of these contactors are connected
in series in the main circuit between the trolley base and the controller and are en cl osed in
an iron box for protection. Additional contacts are provided in the controller for opening
aad clonnff the operating circuit of the contactors when the controller is turned oo or <»
fe^MCtivefy. By this arrangement heavy arcing is avoided at the controller. This
equipment also includes overload devices, tripping switches for interrupting the enef]^izing
dfcuit of the oontactor coils in case of overload. These switches perform we function of
the drcuit breakers ordinarily used, and are located in the cab convenient for opeimtion by
the motorman. They are adjusted, set ood tripped the same as a circuit breaker but only
open the small enexgudng current of the contact coils. A combined switch and fuse, m
connected in the contactor operating ooil circuit. Where the auxiliary contactor (
ment is used, the car circuit breakers are usually replaced ?rith som-aatomatio
blowoat switches, for opening the main circuit when desired. o
2,576
HAWKINS ELECTRICITY
12
CONTROUEH
m*^ kOTOU 1 A 1 WOTOM t « t
Pigs. 3,682 to 3^503. — ^Westinghouse type K-12 con-
troller connections. In changing the motor connec-
tions from series to parallel, it will be noted that the
controller ^ort circuits one pair of motor, but the
current continues to flow to the other pair. The
aeries method here employed consists in connecting
the total amount of resistance in series and then pro-
gressively short circuiting the various connections
until all are cut out.
Alternating Cur*
' rent Control Sys>'
terns. — The single
phase motor used on
alternating cttrrent
roads has a commu-
tator, and in fact is
almost identical with
the series direct cur-
rent motor, save that
all the iron in the
magnetic circuit is
laminated, and there
is a compensating
winding in the field
magnet whose oflSce
it is to neutralize the
inductance of the ar-
mature caused by the
alternating current
flowing therein.
Ques. How are
single phasemotors
controlled by the
com pensa tor
method?
Ans. The impress-
ed pressure is gradu-
ally increased by pro-
gressively cutting out
sections of the com-
pensator or auto-
transform^.
ELECTRIC RAILWAYS
2,577
Ques. What is the objection to rheostatic control as
compared with the compensator method?
Ans. The compensator method is the more eflScient.
Ques.
control.
Describe the induction regulator method of
Pigs. 3,594 to 3,618 — ^Westinghouse tjrpe L-2 controller connections. This type controller opens
the circuits to both motors before making the change from series to parallel. In this parallel
method additional sections of resistance are connected in parallel with the first section
on each successive step. The value of the resistance in circuit is decreased as each new
section is added in parallel with the first section and, finally on the last step the entire
group is sh ort circuited.
NOTE. — Joneg three speed controi •ytenu — This control which is used on the Pitts-
burgh low floor cars, provides three running points, one full series, one series — parallel and one
parallel, the points between, where there are one or more idle motors, being simply transition
points. This arrangement makes possible the changing of the motors from the f ullsenes to full par^
allel relation without breaking the initial series connections between the motors. These origmal
connections are maintained and the various changes effected by short circuiting one or more
motors and establishing circuit connections of a character to cause the current to flow through
both the fields and armatures of some of the motors in a direction reversed to that in which it
flowed in the series position. On the first point all four motors are connected in series through
a resistance, on the second point this resistance is cut out, which, on a 600 volt circuit, makes
150. volts drop across each motor and makes the second point on the control a running point.
The thir4 point is made by manipulating two switches which short circuits two motors and place
300 volts across each of the other two. The fourth point simply closes the grotmd connection
to the two idle motors which makes 300 volts across all four motors and parallels the two pairs.
Transition is made from this fourth point, which is a running pointy to uie next running point,
wliiG^ is the seventh ^ by first providing connections which short circuit one motor and place
one across 600 volts m parallel with the other two in series with 300 volts across each; then
short circuiting another motor circuit beyond the first controller position, it thus also reduces
the weight of resistances which must be carried on the car.
2,578
HAWKINS ELECTRICITY
Ans. An induction regulator (fully described in Chapter LX,
Guide No. 7) consists of two coils: a primary, and a secondary,
which are wound upon separate cores and are capable of angular
adjustment for changing the direction of the flux from the
primary through the secondary so that the voltage generated
in the secondary increases or decreases the voltage supplied
to the motors by the auto-transformer according to the i^ative
angular position of the secondary to the primary.
' I
Controller
- WO-nhr Oi
Pigs. 8,610 to 3,628.— Westinghouae type K-35 controller connectioDa.
Clearly, the voltage induced in the secondary of the regulator may
be made to buck or boost the voltage applied to the motor from the
auto-transformer, by any amount within the range of the regulator.
By making the range oi the regukttor equal to one step of the auto-
tiansformer, full control is secured without shock; thus, the first position
of the r^fulator lowers the transformer voltage by one half step. On
turning the r^;ulator the voltage reduction g^dually drops to sero;
as the tunung is continued, the regulator ddHvers a rising additional
voltage which gradually reaches the value of one half st^» and tfail
equals the next higher step on the transformer.
ELECTRIC RAILWA YS
2,579
Ques. What are the objections to the Induction
regulator method?
Ans. Considerable weight, low power factor, and complexity -
of the apparatus as compared with the compensator method.
pio. 8,620. — Diagram of connectiona of Westinghouae auxiliaiy contactor e9uipment. The
wear and tear on drum controllers may be reduced and life ot the contacts mcreaaed by the
use of auxiliary contactor equipments. A contactor equipment consists of a poi^srful
pneumatically operated switch, or "contactor," mounted beneath the car and connected
to the main reservoir of the air brake system. The switch is controlled by means of a
magnet valve, which is ox>erated by current from the trolley. The circuit or .this magnet
valve is carried through a pair of auxiliary contacts located on the drum of the ooatroller.
When the handle is moved toward the off position, the circuit of the auxiliary contacts*
and hence the circuit of the magnet valve is broken before the main power circuits are
broken, and thus the main power circuit is always opened by the pneumatically operated
switch beneath the car rauier than by the controller contacts. The auxiliary circuit is ,
carried also to a small trippingswitch, located near each controller, and corresponding to i
the usual car circuit breaker. This switch is so arrtuiged that an overload or "short" in the
main circuit will release the handle of the tripping switch, thus openingthe auxiliary
circuit and causing the contactor beneath the car to open the main circuit. The air supply
for operating the contactor is carried throufl^ an auxiliary reservoir and a check valve
before going to the jmeumatic cylinder.
2.580
HAWKINS ELECTRICITY
Figs. 3,630 to 3,633.— Con-
struction details of West-
inghouse auxiliary con-
tactor equipment. Fig.
3.630, tripping s'Tvitch; fig.
3.631, pneumatically op-
erated line switch; fig.
3.632, electrically oper-
ated contactor in iron box ;
fig. 3,633, auxiliary con-
tact attachment for type
K-28 controller. The elec-
trically operated con-
tactor shown in fig. 3,632
is used in cases where a
supply of compressed air
is not available; it oper-
ates in the same way as
the pnetomatic type, ex-
cept that the auxiliarv
circuit closes the switch
directly by means of a
magnet coil, instead of
operating a magnet valve.
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ELECTRIC RAILWAYS
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Three Phase Induction Motor Control.— As outlined in
the classification of control system, there are four methods of
control for three phase induction motors. The changeable pole
and cascade methods were extensively tried out by German
manufacturers, and have been practically abandoned because
m
1 of connections Westinghouse unit switch control (type HL) for quadruple
1 75 horse power motors or less. In type HL control toe various mam circuit
PlC. 3,634.— r
equipment c ^ ^
connections between trolley^ starting resistors and motors (which, in drum type control,
are made by the overhead circuit breaker and the power drum and contact fingers of the
controller) are made by pneumatically operated switches assembled in a common frame
designated as a switch group, which is located underneath the car. Each switch is closed
when desired by compressed air from the brake system, acting on a piston. The reversing
connections ordinarily made by the reverse drum of the platform controller are made by a
teverse drum similar to that of the controller, but of more substantial construction, pneu-
matically operated and mounted in a separate case underneath the car. The complete
leverse drum with its operating mechanism is termed a reverser. The admission or
felease of compressed air to the pistons for operation of the switches and reverser is regu-
lated by means of electrically operated ma^et valves, one of which is attached to each
piston cylinder. The circuits from the various magnet valves are controlled by a mastef
controller on either car platform through a control train line, which extends the length
of the car and terminates at each end m a twelve conductor train line receptacle. By
moving the handle of the master controller from notch to notdi, the various switches in
the switch group are operated and the proper motor connections are established. If the
adjacent train une receptacles on two or more cars be connected by suitable train line
jumpers, the operation of either master controller on any car wiU cause the various switchei
on ul of the cars to close or open simultaneously for tram operation.
2,682
HAWKINS ELECTRICITY
of their complications. In addition to the complications, the
rheostatic method must also be used with them to provide the
smaller gradations of speed.
Ques. How is rheostatic control applied to three
phase induction motors?
Ans. By arranging a variable resistance in series with the
o.a.snuuNM
8,035. — ^Arranffement of piping of Wettisffhouse unit switch control, type HL. Tbe pHmos
here ahown is for the oompre^ed air whioi operates the control apparatus, the air aupphr
being taken from tht brake system. The air passes through a cut out cock for shutting off
being taken from tht brake system. The air passes through a cut out cock for shutting <
the supply if desired, a hair strainer for removing dirt or scale, and a reducing valve* witii
egualiimg reservoir and check valve for maintaming a tmiform pressure. The amount of
air reqtured for operating the switches is so small compared to that required by the bxalcet
and wmBtle that it is practically negligible.
armature winding and progressively reducing it as the motor
speeds up, till at full speed or the last step of the control all
the resistance is cut out.
Ques. What type of motor is used for rheostat^ control?
ELECTRIC RAILWAYS 2,883
Ans. The slip ring or external resistance form of induction
motor.
Ques. What kind of resistance is used?
Ans. Resistance in the form of grids or liquid.
In the case of liquid resistance, the electrodes which dip into the
liqtiid are held stationary and in the process of reducing the resistance,
the level of the liquid is raised by compressed air, the influx of whidi
18 regulated by an air valve controlled by a magnet in the motor circuit.
Fto. 8.680.-- Weitiflghotue unit switch with sides of box, arc chute, cylinder and vahre cut away.
The construction of the switch includes two stationary copper castings, one of which forma
directly the upper or fixed contact, while the other serves as a support for the lower or
movable contact. The current carrying parts are enclosed in an insuuiting box of moulded
material, in addition to which the jaws of the switch are further surrounded bv an arc
chute ahpped inside of the switch box to protect the latter from the arc. The switch
secured to the base i>late of the switch group by two copper bolts, one of which is screwed
into each of the stationary castings; and these same bolts serve as terminals to cany the
current. By merely removing these two bolts the entire switch unit, complete with msu-
lating b9x and arc chute, can be readily taken out. The force with which the switches
operate is independent of the force with which the magnet valves operate. As long as the
trolley voltage is sufficiently high to operate the magnet valves at all (200 volts), the
switches close and remain closed with the same certainty and power as when the full normal
▼oltage of 000, or more is available.
Finally the resistance is automatically short circuited by a switch
governed by a float. To cut in the resistance the liquid is depressed by
air pressure.
Ques. Describe the changeable pole method.
Ans. In this method the number of pole may be ^SSM to
2,584 HAWKINS ELECTRICITY
secure variable torque either by providing the motor with
independent field windings, or by regrouping the field coils.
Ques. Which changeable pole method is preferable
and why?
Ans. The regrouping method because it utilizes all the
winding.
Fig. 3,637. — ^Westinghouse cylinder and magnet valve cut to show worldng parts, tn operating
the reaction of the spring;, when compressed by the admission of air to the cylinder, is 120
pounds and the leverage is such that the pressure of 100 pounds appears at the switch jaws
for forcing them apart. The same construction which secures the wiping action of the
contact tips when the switch is closing is also of considerable b^efit when it is opening,
and an efficient application of the above force is obtained. The size of the air cylinder is
such that the net pressure at the jaws for closing the switch is also approximately 100
pounds at all times of operation. The low voltage current from the trolley, through the
control resistor, for operation of the valves is so small as to permit their arrangement for
operation under a wide variation of trolley volta^s. The assembled unit of cylinder a^
magnet valve is so sectired to the frame of the switch group by means of two bolts that,
like every other part of the group, it can be easily removed and replaced, should this
become necessary.
Ques. What other names are given to cascade
operation?
Ans. Concatenation, and tandem control.
Ques. What is cascade operation?
Ans. The various combinations of connection of two motors.
In the concatenation of two railway motors, the armatures are
mechanically connected, the field of the first is connected to the supply
and the armature to the field of the second motor: the arpature of the
ELECTRIC RAILWAYS
2,585
seoond motor is connected to the external resistance at start. As the
motors speed up, the external resistance is cut out tUl armature of second
motor is short circuited. For motors of equal ntunber of pole, after
reaching maximum speed, they may be s^iarated and each, having
resistance inserted in its' armature circuit, may have its field consiectea
Pigs. 3,638 and 3,639.— Westinghouse blow out coil. Pig. 3.638 view with side of box cut away:
fig. 3,639, complete with pole piece. Bach blow out coil consists of a number of turn of
copper strap enclosed in an insulating box similar to the switch box. Bach coil is secure
to iJie base plate of the switch group by two cox>per bolts, in the same way as the switches.
« W ii ;,
Fig. 3,640. — ^Westinghouse switch group, covers removed, front view. The most important
item of a control equipment is the switch group. This consists of a cast and malleable irop
frame upon which the various switches are mounted, completely enclosed by three easily
removable sheet iron covers. A blow out coil is located at the side of each switch in order
to extinguish the arc formed when the switch is opened under load. The motor cut out
switches and the control circuit terminal board are located in a suitable compartment on
one end of the group, and the overload trip, when not mounted on a line switch, is on the
other. The term unit switch as applied to this system of control signifies that the funda-
mental pieces of ax>paratus have all i>arts arrange on the unit plan, so that any worn, or
dama^d part may be removed and replaced. A switch group, for instance, is .made up by
assembling the reqxiisite number of each of four different units, known respectively as the
switch, the cylinder, the magnet valve and the blow out coil, these being described in ^he
accompanying cuts. ^ . ^
2,586 HAWKINS ELECTRICITY
to the supply. For maximum effort the earternal resistances may now
be progressively cut out resulting in full parallel operation.
Ques. Describe the single control cascade method.
Ans. In this tnethod the second motor is cut out after the
period of concatenation.
Ques. Describe parallel single cascade control.
Fig. 8,641. — Westing^ouse standard reverser* covers removed. The reverser comxmaes a
number of copper fingers mounted on a stationary base, and pressing on one or toe other
of two sets of movable contact carried on a wooden drum. The drum is revolved to the
forward or the reverse position by one or the other of two pneumatic cylinders, each ^ con-
tiolled by a magnet valve similar to those in the switch group. Powerful forces approximat-
ing those for operating the switches, are used for moving the reverser, so that heavy preasores
on the fingers and firm contacts are thus secured. This construction'gives the reverser , large
overload capacity for taking care of heavy current rushes. No springs are used in the
reverser cylmders and the drum, when moved to one position by closing the circuit of one
of the magnets, remains in that position until the circuit of the 9ther magnet is closed.
Suitable small fingers mounted upon the reverser frame, and pressing upon corresponding
movable contact pieces on the reverser shaft, establish the necessary interlocking connec-
tions. The reverser parts are built upon a skeleton cast iron frame and enclosed by remov-
able sheet iron covers.
Ans. In this method motors are employed having a different
ntunber of pole, or different gear ratios.
In operation, when the motor with the greater number of pole reaches
synchronism, it is cut out. If the motor with the lesser ntunber of
pole be cut out instead, the train will operate at a speed between that
corresponding to concatenation and that for the free running of the
motor with the lesser number of pole with armature short circuited.
Ques. How are the changeable pole and cascade meth-
ods combined ? ° srt'^®'^ ^^ ^ o
ELECTRIC RAILWAYS
2,687
Ans. By first making the sequence of pole change and thea
applying either of the cascade methods, thus giving several speeds.
Combined Direct Current and Alternating Current
Control. — In changing from alternating current to direct cur-
rent (or from direct to alternating) it is necessary to guard
against the possibility of wTong connections upon the car for
Fig. 3,042.— ^Westinghouae flUndard resbUnce grids for railway servi«i» These i^iids afB
dirajiErned with the object of piroviding ample mecbanieal strctifTtb and Utwral tmrretit carryixig
capacity. Individual grids of sufflciiefit section to resist breakage are used; and this*
toflether with the tri&nfe^ukT arrafigcment of the tits rods, makf^ the assembled £nune8
strong and solid.
the current received, that is, to prevent disaster should con-
nections be made for 600 volts direct current operation and
accidental contact be made with 6,600 volts alternating current
trolley. To guard against this, the main switch of the direct
current and alternating current car equipment is provided with
a retaining coil so designed that it will open when the motor
current is interrupted. Where alternating current and direct
current trolley sections adjoin, a dead section is left between
2,588
HAWKINS ELECTRICITY
the two for a length not exceeding a car- length, so that a car
may pass from one section to the other at full speed, in which
case the main cai switch opens on the dead section through
lack of power to operate the retaining coil, and will reset
Figs. 3,643 and 3.644. — Westinghouse master controller. Pig. 3,643 view with cover removed;
fig. 3,644 with cover in place. The master controller contains the usual power and reverse
handles, mutually interlocked. Except for the smallest sizes of equipments, it is arranged
with five notches in series and four in parallel. The position of the notches is indicated oo
the cap plate of the master controller and also by a suitable star wheel inside of the case.
automatically for alternating or direct current operation as the
case may be, after leaving the dead section.
Electric Locomotives. — Numerous t5rpes of electric locomo-
tive have been built for a variety of purpose, from yard switching
ELECTRIC RAILWAYS
2,589
to the hatding of heavy passenger trains at high speeds.
They may be classed
1. With respect to service, as
a. Switching;
h. Freight;
c. Passenger;
d. Industnal;
2. With respect to the running gear, as
a. 'Single truck;
b. Double truck;
c. Double truck with trailers;
d. Articulated, etc. ;
Fto, 8,645. — ^Westinghouse control resistcr. This is used to reduce the trolley voltage for
operating the magnet valves. The resistance element is of the slotted ribbon type, and is
iron clad to protect it from the weather,
3. With respect to the transmission, as
a. Gearless;
h. Geared;
c. Connecting rods;
d* Scotch yoke;
e. Combination gear and connecting rods;
4. With respect to the power source, as
0. External;
b. Storage battery;
c. Gasefectric.
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2,690
HAWKINS ELECTRICITY
The accompanying cuts give example of various types of
electric locomotive construction.
. Ques. What is a gearless locomotive?
Ans. One having the armatures built on the axles of the
driving wheels.
Ques. What is a geared locomotive?
Ans. One in which the motor drive is through gears.
iTiC. 3,fl46. — < tener:i! Biwtnc 100 ton locomoth'i:: f-:^ rtiJxl^rAtc epecd heavy pnssenifnr azvi
freight service. There are four 300 horse power motors of the box frame, commutating
pole forced ventilated type. Bach of these motors at its one hour rating will develop a
torque of 4,000 lb. at a one foot radius. The gearing between the motoi and driving ucfo
has a 4.37 reduction and the driving wheels are 48 in. in diameter. With this feductioa
each motor will develop a tractive effort of 8,750 lb. at the rail head^ which gives a total
tractive effort for the four motors of 35,000 lb. This tractive effort will be developed at a
K>eed of 12 miles per hour. The four motors have an overload capacity sufficient to slip
the driving wheels and can develop under maximum conditions a momentary tractive effort
of 60,000 lb. to 60,000 lb. The maximum safe speed of the locomotive running light is 36
to 40 miles iper hour. The gears are shrunk on to an extension of the driving ^eel hub
and there are two gears and two pinions per motor, one at each end of the armature shaft.
This form of construction is adopted on account of the unusually heavy torque and the
excessive overloads to which the motors are liable to be subjected in heavy railroad service.
The control comprises two master controllers located in the cab. There are two four wheel
trucks with articulated coupling.
Ques. Describe the side rod driver.
Ans. In this method, the motors are placed in the cab and the
driving torque communicated to the drivers by means of con-
necting rods. Digitized by GoOglC
ELECTRIC RAILWAYS
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c a -J tH^ o
4J «»H t
2,592
HAWKINS ELECTRICITY
Ques. Describe the Scotch yoke arrangement.
Ans. The yoke drives one axle through a sliding block and
the others through rods connected to the yoke by laiuckle pins.
Ques. Describe the combination gear and connecting
rods.
Ans. In this drive the motors are geared to jack shafts
which in turn transmit the power to the drivers by means of
connecting rods.
Pig. 3,661. — Plan view of a Westinghouse mine locomotive showing two motor equipment,
geared drive, brakes, controller, resistance grids, etc.
The Running Gear. — There are two general types of truck
for electric cars: 1, those in which the car body rests upon the
truck bolster or side bearings which are supported by springs
for the side frames carried by the axle journal boxes as in the
case of the Brill maximum traction truck shown in fig. 3,652,
and 2, those in which the car body rests upon the truck bolster
supported from the truck frame which rests upon springs
carried by equalizer bars resting on the axle jotimal boxes, as
in the case of M. C. B. or Master Car Builders type of truck
shown in fig. 3.653. . ^
ELECTRIC RAILWAYS
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HAWKINS ELECTRICITY
Ques. For what service are maximum traction trucks
extensively used?
Ans. For city street railway cars where the numerous stops
required demand a high rate of acceleration.
This is secured by supporting the weight of the car body between
the center of the truck and the axle canying the motor so that seventy
five per cent, of the total weight of the car falls on the larger or driving
Pigs. 3,654 ^vA ..,■■'■■"■. Two ajrangements ot motors. Vv^,. 'ijVy\, tan'iem bitng; fig. 3,655
inside hyny, Tiu' triTujcm method Qcnriits a locomotivu - ■■ ^ • . !•.■ with a short wheel
base and u.i the saxne. time with gaotf riiifti^ qtjalitics, Th-; ■ . .lur^ f rack, and ctirve
limitations, of mine seTvico malte this the pre\'ailing EJTaiVt^um'j.^i. Where a locomotive
car has a large wheel base, the inside lining arrangement is generally used, as tmder such
conditions the weight is better distributed.
wheels of the truck. The idle wheels, which are commonly known as
the pony or guiding wheels are made of much smaller diineter than
the driving wheels in order to permit them to clear the under frame of
the car when the truck swivels on curves.
Ques. What use is made of the M. G. B. type of truck?
Ans. They have been designed to satisfy the greater weight
ELECTRIC RAILWAYS
2,595
and higher speed requirements of the rapidly extending inter-
urban electric railways.
So long as the weight of the cars and the power required to propel
them remained comparatively small, the designs for electric car trucks
were naturally developed enturely from street railway practice but when
it became necessary to apply as mudi as 400 horse power to a trudc, it
was quickly recognized that the solution of the problem depended
upon or the correct application of the principles which have been so
carefully and thoroughly worked out on steam locomotives. It must
be understood, however, that the conditions are not exactly the same
in the two cases. For instance, in the electric motor truck the driving
Figs. 3,656 and 8,657. — ^Westinghouse selMubricating bearing. Pig. 3,656 type used on box
frame motor; fig. 3,657 type used on split frame motor. As shown in the sectional views,
the bearing housing has a, separate oil pocket from which the oil is fed and which majr. at
any time, be gauged. With this arrangement there, is no excuse for wasting oil. The
inspectOTpours only enough oil into the chamber to bring the free oil up to a predetermined
depth.. With the supply of free oil nommlly below the level of the oi)ening m the bearing
there is no oil wasted when the motors are at rest through dripping or draining. The
bearing is provided with suitable wiper rin^, that prevent an over supply of oil work-
ing into the motor and damaging the windmgs. In addition, it has an easily accessible
drain chamber, that catches the on as it works out of the bearings. There is no variation in
saturation of the waste. In modem Westinjshouse motors the armature bearinjss are
lubricated on the low pressure side. With this type of bearing it is usually sufficient to
renew the oil once a month.
wheels and the truck wheels are combined, and are necessarily much
smaller than the driving wheels of a locomotive. Furthermgre, the
high speed motor truck cannot have any other guiding wheels other
thiji the driving wheels themselves, and must possess good riding
qtffiJities for the protection of the electrical apparatus.
2,596
HAWKINS ELECTRICITY
Brakes. — ^Next to the controller, the brake is the most
important device provided for controlling the motion of a car.
Its function is to slow down or stop a car at any desired place,
Pig. 8,658. — Internal arrangement of General Electric platform type storage battery looomo-
tive. Since the energy required for propelling the locomotive is obtained from storage
batteries and is, of necessity, limited in amount by the space which is available for installing
such a battery, it is desirable to keep the speed ox such machine comparatively low in order
that the pulling power may be retained to a value within the limits of the battery capacity.
The cost for power will vary from 60c to probably $2.60 per charge per locomotive, depend-
ing upon the tjrpe, size and efficiency of the batteries furnished, as well as the efficiency of
the charging equipment: The cost of power is here considered at 6 cents per kw. hr. The
frequency of charge will depend on the severity and conditions of service.
after the power has been cut off and the car is being propelled
by its own momentum. As this momentum is overcome by
ELECTRIC RAILWAYS
2,597
^1
la
H
the friction of the brake shoe
on the car wheels, it is
obvious that the longer the
interval of time allowed be-
tween the cutting off of
the power and the ap-
plication of the brake, the
less will be the labor required
of the motorman to apply the
brake; while the wear and tear
on the rolling stock and the
amount of power wasted would
be correspondingly reduced.
Therefore, in order to oper-
ate a car successfully, that is,
to maintain the schedule time
with a minimimi power con-
sumption, the controller and
the brake should be used in
connection with each other,
intelligently and with good
judgment. ^
There are several types of
brake used on electric cars:
1. Hand brakes;
2. Airbrakes;
3. Electric brakes,
Ques. Describe a hand
brake.
Ans, It consists of a ver-
tical brake staff securedjto the
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2,598
HAWKINS ELECTRICITY
Pig.
3,660, — Diaj^ram of band bmke system shomngr the chAia of connection horn the i^_
handle to the brake sbQes^ and tha leverage employed at the various points in the ii&fidi
brake system incist commonly used on trol!e>^ cars. The tensions m the conjiettiooil
and the bmke ahttfi pressures are tbas^' resultinc from the apnlJcBtion of 50 poundj of!
pressui* at right arigles to the horiaiontal arm of this brake handle, On^j of the objection-i
able features of this Brrsingetnent is the use of a. single sway^ bar and jfaHiitjf iarr, ^hieh^
results in the application of the greater braking pressure, to the rear wbeela or tnlck kt-\
stead of to the imtit wheels or tmcka where it should be applied to secure the most -^ -■"
ive bralDOg, as sh&wn in fig. 3,G67*
Pic. 8.C61. — General Electric gas-electric direct connected set for gas-electric motor cat
showing control levers. It consists of an eight cylinder, 550 r.^.m., foor cycle, pas engine
of the V type, direct connected to the dynamo. Cylinders, 8 in. diameter, 10 m. stroke.
This set supplies power for the motors and compressed air for braking and air start.
Starting is accomplished by compressed air. A two cylinder, auxiliary gas engine wi^
integral air compressor provides an initial charge of compressed air for air start and brac-
ing reservoirs. A dynamo, direct connected, supplies current for car illumination and
headlights. The controller regulates the voltage and in addition places the motors pro*
gressively in series and parallel. Located on the controller are also separate handles for
throttling the engine and reversing the driving motors. Two standard type, 600 volt,
box frame, railway motors, 100 horse power each, are mounted on the axles of the front
trucks, are inside htmg and equipped with standard gears and gear cases. The trucks
are of the high speed, all steel, swing bolster, equalized type. Wheels, 33 in. diameter
with M.C.B. beajings, wedges, treads and flanges. A fin tube radiator is mounted oo
cab roof, thermo-syphoo circulation. The gasoline tank has a capacity of 150 gals.
ELECTRIC RAILWAYS
2,599
1-2^ prill
aj tj. t, K —
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V,o*^^^.
p:^||11
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ill 11^
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2,600
HAWKINS ELECTRICITY
end of the car, at the dash board and to the left of the controller.
The upper end of the staff carries a crank or wheel by means of
which it may be rotated by the motorman so as to wind arotmd
its lower end a short length of chain connected to the brake
lever system through which the manual force exerted on the
Figs. 8,664 to 3.666. — Center and side bearing. Pi^. 3,664 center bearing for city and intw"
urban service: fig. 3,665, side bearing with 9 inch travel; fig. 3,666, side bearing ^
ya inch travel for interurban cars operating on short curves. The center and side bear-
ings of a trudc form the contact pomts between itself and the car body. The car bodv
is practically carried on the center plates on the truck bolster and comes in contact with
the truck onlv at this point; but in order to prevent more than a slight displaconent of
the car body from the vertical, side bearings are placed over the side frames ol the trucks,
and so adjusted as to leave sufficient space between side bearing top plate and the plate
on the car to take up the maximum compression of the springs when uie car is fully loaded.
It is a fact, however, that owing to a lack of adjustment, or from the displacement of the
car bod^ from the vertical when rounding curves due to, the excessive elevation of the
outer rail, the side bearings on one side may be brought into solid contact with the car
body. In order to facilitate the swivelling of trucks when rounding curves ball bearings
are frequently used in place of the ordinary bearing plates.
brake handle is multiplied in amount to the desired direction^
and applied to the brake shoes which press against the wheels
of the car.
Fig. 3,660 shows a typical hand brake gystdiif."^ ^^ GoOglc
ELECTRIC RAILWAYS
2,601
Ques. How do air brakes operate?
Ans. By power derived from compressed air and applied
te the brake levers by means of a brake cylinder.
There are two systems of air brake, which are distiiiguished from
each other by the method employed for admitting the oox4pre8sed air
to the brake cylinder.
VlG» 3*^7. — Geared brake. This apparatus has a pinion A, on the lower end of the hraki
rtaff, which enga^ a gear B, made in one piece with a double sprocket wfaeeL The two
chain k)0ps running throufi^ these sprocket wheels engage two hooks formed on the end
of the brake rod, or two separate brake rods which are attached at the same point the
•way bar. The upper chain is the only one used in braking, the other being left slack
and held in reserve for use if the first set fail to woric. When the brake is applied to a
oar mounted on maximum traction trucks as shown, the difference in pressure between
the brake shoes on the driving wheels and those on the pony wheels is obtained by means
of a spring interposed between the brake system and the pony wheel brake shoes. The
dimensions of the different levers are as follows: Lenfi[th of sway bar C is 48 inches; dis*
tance D between pins for the arch bar rods B and P is inches; length truck lever B is
13 indies; and length of horizontal part of brake handle K is 15 inches. "With levers
of these dimensions a fpr(^ c^ 65 pounds applied at the brake handle gives a total brak<
ing jnessure of 29,000 pounds, or an amount exceeding the weifl^t of an empty car. The
best proportion of the lever is secured when, (C +D) X (G X H) X 85k -total weight of
the empty car.
In the ''strai^t air** brake system, the air from the reservoir is
piped to the motorman's valve, which is so designed that when the
* vahre is turned to the position for applying the brakes, the air passes
into the pipe running du'ectly to the Drake cylinder. ^
2,602
HAWKINS ELECTRICITY
TO TRCLIXV
Pig. 3,668. — Diagram of automatic air brake svstem. This arrangement is very dmilar to
that used on steam railway trains and is adopted for use on electric railway trains com-
posed of more than two cars. It differs from the straight air brake in that the com-
pressea air instead of passing directly from the air reservoir through the train pipe, to
the various brake cylinders, passes from the train jpipe into auxiliary reservoirs connected
with each brake cylinder, as here shown, where it is stored and automatically operates
the brake mechanism in response to the movements of the motorman's valve handle.
When the motorman turns the valve handle to the position which allows the air t(k imms
from the main reservoir into the train pipe, the triple valve on the several cars allow the
air to flow into the auxiliary xeaen^irs. The system is now in the proper condition for
ELECTRIC RAILWAYS
2,603
In the ^'automirtic air** brake system the air from the reservoir is
admitted to auxiliary reservoirs which are connected to the brake
cylinder by means of special devices called the *Hriple valve.**
The straight air brake system is adopted to single cars or short trains
composed of motor car and one or two trailers. It is not suitable for
longer trains on account of the objectionable length of time which
would be required to supply the quantity of air necessary to fill the
brake cylinder.
:\ uA,m iijjrjf^Sn77r7!^g^^^L2g^g^ ul^JS
Figs. 8,069 and 3,670. — Elevation and inverted plan of storage air brake equipment as in-
stalled on car.
Pig. 3,668. — Description continued,
setting and releasing the brakes. When the motorman moves the valve handle to the x>osition
{or setting the brakes, the action of the valve cuts the communication with main reser-
voirs and i>ermits the air to escape from the train pipe. The consequent reduction of
pressure in the train pipe causes uie triple valves to open a connection between the aux-
iliary reservoirs and the brake cylinders, which allows the air to enter the latter and
set the brakes. To release the brakes the motorman must again turn the valve handle
to the position for admitting air from the main reservoir to the train pipe. ^ The pressure
in tiie train pipe being thus increased above that remaining; in the auxiliary reservoirs
causes the triple valves to take a position which allows the air m the train pipe to pass into
tiie auxiliary reservoirs, while at the same time the air in the brake cylinder is allowed to escape
to the atmosphere throu^ the triple valve exhaust posts, thus releasing the brakes.
Prom the foregoing descriptions, it will be noted that in the straight air system, air is
admitted to the train pii>e to set the brakes, while in the automatic air brake system air
is admitted to the tram pipe to release the brakes. In the straight air system, the, train
pipe is never under pressure except during the time the brakes are applied, while m the
automatic system is always under pressure, which is greatest wheii the bnJces are re-
2,604
HAWKINS ELECTRICITY.
Car Lighting. — ^This is largely a uiatter of taste and judg-
ment, the arrangement and power of the lamps depending
upon the size of the car and the character of the service. In-
candescent lamps are used almost universally for both interior il-
Itunination and for headlights. Cars of ordinary size usually have
a cluster of three lamps in the center of the ceiling and one at
each end. Larger cars have a row of single lamp placed at a
convenient height above the seats, and an additional row, or
one or more clusters of lamp along the center line of the ceiling.
^jrjE SIDE OF HEATER SWITCH
/^TO BE USED FOR LIGHTS
3 WAY SWITCH TO BE PLACED
OVERHEAD AT FRONT OF VESTIBULE
3 WAY SWITCH
r 3 WAY SWITCH
CEILIHG LIGHTS
RESISTAHCE-H
SWAY
SWITCH
6R0UMD\
Pig. 8,071. — Car lighting wiring diagram showing head light in series with interior lan^M.
In this case there are five circuits of four 16 c.p. 110 volt, H amp. lamps each, operatmg
oo a trolley volta^ of 650 volts, therefore, 110 volts from each circuit goes to the head
light, thereby givmg 2H amp. of current which is sufficient for a 80 c.p. incandescent
lamp for city cars, or a 2H ampere arc lamp for interurban cars. The wiring diagram
shows 7 lamps on each side, 4 lamps on the ceiling, one lamp in each vestibule and one
lamp for the illuminated sign at each end of the car. A three way switch is located in
each vestibule by means of which either the vestibule light or the sign light at either
end may be cut out of circuit, thus keeping only 20 lamps in service at any one time.
A three way switch for cutting out eitho* head light is also provided at each end of the
car. When neither of the head lights is in use, a small resistance inserted in the ground
connection is cut into circuit to tiOce up the 2H amperes usually taken by the head lig^t.
These lamps are, usually, connected in series on a special lamp circuit
with the trolley, the wiring being very much the same as in the case of
ordinary house fighting. The lamp on each platform is usually wired in
series with the head light on the other end of the car, and a changeover
switch is provided for throwing into circuit the proper platform lamp
and head light whenever the running direction of the car is changeo.
It is quite practicable, however, to connect the head lipht to the
interior lamp circuit as shown in fig. 3,671, thus eHminatmg the re-
sistance used with the independently wired head light and effecting a
great saving of current. o
ELECTRIC RAILWAYS
2,605
The following brief descriptions give the essential features of
some typical axle lighting systems.
The Stone System. — This eqtiipment was invented in 1895 by Mr.
A. B. Gill, and was developed and improved by Messrs. J. Stone & Co.,
of Deptford, England, hence is known as the Stone system. It has
reached aknost tmiversal adoption on the English railways.
Fig* 3,672. — Safety Lighting Co. axle driven djmamo. It is a four pole machine, with single
shunt winding designed to give aparkless commutation at varying speeds and varying
loads met witii in car lighting. The frame is a one piece steel casting, the supporting
lugs being cast solid with the Irame. Annular ball boaings are used. Space is provided
around the bearings for grease for lubrication. Greasdgrooves and felt washers prevent
the entrance of dirt into the bearings and the leakage of grease into portions of the aynamo
where it should not go.
NOTE. — It is a tradition that the honor of first lighting railway cars belongs to one Thos.
Dixon, the driver of the ExperimetUf as the coach was called, on the Stockton & Darlington
Railway, England, in 1825. It is said that on the dark winter nights, out of pure goodness of
heart, he used to bring in a penny candle and set it on the rough oak board that served as a
table in the center of the coach. In those dajrs the railway companies made no effort to light
their cars except to offer candles for sale to passengers. Gradually times changed and the
railway companies furnished a few smoky candles to be placed in each car. This was only to
enable the passenger to find his way in and out of the car and took no thought of his real coxnifort
and accommodation. Later, oil lamps were substituted in place of the candles, and these, tbou^di
at first only a slight improvement over candles, were improved and developed to give a fairly
good light as the railway practice develcmed. Car lighting has followed the same general lines of
development as have tiie common methods of house and street illumination, but at no time
till wiuiin the last few years has any method of railway car lighting been equal to that employed
in houses or public places. The reason for this is obviously in the great difficulty of adapting
any method of illtunination to the severe conditions of railwaif service. But, nevertheless,
practically ,all of the house and street illuminants have been utilized in lifi^tin;; railway trains
and in addition to this the vast application c^ compressed Pintsch gas for lighting railway cars
has been developed, and later, various systems of electric lighting. ^
2,606
HAWKINS ELECTRICITY
The characteristic feature of the equipment is that each car is a unit
by itself, thus affording a much more flexible system th^i that of the
earlier sjrstems of England, where the djrnamo was located in the
guard's van, this being suitable for block trains only. The equipment
consists essentially of a d3mamo, a storage batteiy to act as auxiliary
when the dynamo is inoperative, and an automatic switch to dose the
dynamo circuit when the critical speed has been attained.
The principle underlying the operation of this equipment is that
r^:ulation is obtained by allowing the belt to slip. As the speed of
the train rises the djmamo volt^ewill tend to rise proportionally,
this causing a great battery chargmg current to flow, thus increasing
the dynamo output and belt pulL The method of motmting the dynamo
is shown in fig. 3,673.
Pic. 3,673. — Method of dymuno suspension in Stone system. As, shown, the dynamo is su^
ported at one comer of its 9nie by the adjustable link A, in such a manner that it is
tree to swing towaid or away from the driving axle. The suspending link is so placed
that the belt draws the dynamo out of the diagonal position in which it would naturally
hang, thus putting a definite tension on the belt, just sufiSdent to absorb the power re-
quired. It IS obvious that when the pull on the belt exceeds that due to the offset sus-
pension of the dynamo that the dynamo will be drawn toward the axle and the belt
allowed to slip. Thus the dynamo will run at practically constant speed for all values
ci train speed above the critical value. A strong mechanical governor automatical^
ck)ses the dynamo circuit when critical speed has been reached. A storage battery is
suspended underneath the car to act as auxiliary in lighting the lights when the dynamo
is inoperative. Another function of the storage battery is that it acts as a ballast or r^u-
lator to keep the lights constant, absorbing all the variations of dynamo output. Tiie
lubrication of the dynamo is effected by means of an electrically controlled oil supply
8o adjusted ^at when the n/namo is in operation oil will flow from the oil tank, but
when the dynamo is inoperative, the sui>ply is cut off and no waste takes place. The pre-
determined speed of dynamo was 915, at which it delivered 20 amperes.
McElroy System, — In this system the dynamo is mounted directly
on the trucks and is driven by a gear and pinion similar to those used
on the motors of trolley cars; these being enclosed in a wrought iron
g6ar case which is made du6t proof with leather packing.
ELECTRIC RAILWAYS
2,607
2,608
HAWKINS ELECTRICITY
Ques. Describe a common defect in car illumination.
Ans. The use of lamps of high intrinsic brilliancy produces glar-
ing efiEects which are hard on the eyes especially when reading.
Pig. 8,676. — One method of installing Safety Lighting Co. dynamo under a steel car. The
dynamo is a four pole shunt wound machine and has a capacity of 3 kw. or 75 amperes
at 40 volts. It is of the enclosed type to secure protection from dust, flying gravel, etc
The armature is fitted with ball bearings, space being provided around the bearings for
lubricating grease. The direction of current from the dynamo is kept constant by rotat-
ing the brushes through an angle of 90 degrees whenever the direction of rotation of the
armature is changed. ^ The four brush boxes are mounted on a brush rocker and are in-
sulated from it by mica bushings and mica washers with large creepage surfaces. This
brush rocker is mounted on ball bearings^ and is free to rotate between two stops, 90 de-
grees apart, on the head. While running m one direction, the friction caused by the pres-
sure of^ the brushes against the commutator holds the brush rocker Sj^ainst one of ^e
stops, with the brushes in the proper position for sparkless commutation for this direc-
tion of rotation. Reversing the direction of rotation causes the brush rocker to be tamed
over a^inst the other stop, changing the position of the brushes 90 degrees. The dynamo
then gives the same polarity, altQOUjBih the direction of rotation has been re v e rseo.
ELECTRIC RAILWA YS
2,609
The intrinsic brilliancy of a lamp is the intensity of the light emitted
divided by the area of the source emitting the light. For example:
of two lights of equal candle power the one having the shorter or more
closely coiled filament and smaller bulb is the more brilliant, and is
the one that will have the greater tiring effect on the eyes. For the
same reason a large number of low candle power lights distributed
throug}i a car will give a more useful illumination t£an a few high
candle power lights.
Pig. 8,677. — Safety Lighting Co., type P, lamp regulator. It consists of two piles of carbon
discs in series with the lamps; the two piles being in parallel. The presstire on these
carbons, and therefore their resistance, is determined by the armature of a magnet , the wind-
ings of which receive lamp voltage. By a unique design of magnet and levers, a high degree
of accuracy in voltage regulation is accomplished without the use of any auxiliary control.
The carbons C, are compressed by an adjustable spring connected to the link L, acting
through a togsle. The pull of the spring is opposed by the pull of the electro-magnet
which is connected directly across the lamp mams and is so designed that the armature
A will stay in any position through its stroke when the lamp voltage is right. When
the lamp voltage is high the magnet becomes stronger and pulls armature A down against
the pull of the spring and reduces the pressure upon the carbons C, increasing their re-
sistance and bringing the lamp voltage back to nohnal. If the lamp voltage be low, the
magnet becomes weakened, the spring; pulls armature A back, and through the toggle
exerts enough pressure on the carbon piles to decrease their resistance and bring the lamp
voltage back to normal. An air dash pot of the same type as used on the dynamo regu-
lator IS employed on the lamp regulator.
"Axle'' Lighting of Cars.— This method of car lighting is
one now being very generally adopted on steam railways, and
in brief, it consists of a dynamo belted to the axle, storage
battery, and necessary auxiliaries for proper control.
2,610
HAWKINS ELECTRICITY
T:^^
•I
iiminpiiiHipim ,,
>oa.-»
vDOLoao
rOi
Digitized by VjOO^
•8^
ELECTRIC RAILWAYS 2,611
Within the dynamo c»mpartment is a mechanical device that deter-
mines the polarity of the circuit on reversal of the direction of motion
of the car.
A battery auxiliary is supplied as in all other axle devices. This
equipment is one of the type that controls by varying field resistance.
The regulator is the characteristic part of the equipment and consists
essentially of a compound solenoid controlling a motor, which in turn
operates a field rheostat.
The compound solenoid is a part of the equipment that deserves
special consideration. It consists essentially oi a series coil of heavy
wire placed in the battery circuit, and in addition to this a shunt coil
which is connected directly across the dynamo terminals. Thus the
control is one combined for voltage and current regulation and appears,
at least partially to eliminate the evils of the control by constant current.
By a proper adjustment of the ratio of ampere turns of the shunt
coil to those of the series coil, the regulator may be made to protect the
batteries from the destructive overcharge which is so often experienced
when a constant current regulator is employed.
This, from a battery standpoint, is a very commendable improve*
ment over the principle of control by constant current regulation and
deserves special emphasis.
In explanation of the operation of this solenoid, assume actual oper-
ating conditions; there being 16 cells in the storage battery, the dynamo
voltage then varies between 32 and 42 volts at different points of the
battery charge. Accordingly the magnetic flux in the solenoid due to
the shunt coil would vary proportionally to this pressure. This might
be expressed as a variation from 320 to 420 ampere turns. Assuming
that the series coil had been adjusted so that normal charging current
would develop 110 ampere turns, this making a total number of 320
plus 110 equals 430 ampere turns in the solenoid when charge was first
commenced. Now as the batteries become charged the voltage rises
and the shunt coil magnetism is increased, thus requiring less magnetic-
pull from the series coil to regulate. It should be noted that the mag-
netic pull which balances the pull of the adjustable reg\Ulator spring is
the sum of the magnetic pull due to the shxmt coil combined with that
due to the battery current flowing through the series coil, and that as
the one increases the other must decrease to maintain equilibrium.
When charged condition is obtained, the 430 ampere turns total in the
solenoid would consist of 420 ampere turns due to the shunt coil, and
only 10 ampere turns due to the series coil, thus the charging current
has-been reduced to only 9% of its normal maximum value. It is
obvious that by a suitable proportion of ampere turns due to the series
and shunt coils the battery overcharge may be reduced to any desired value.
In regard to the detail operation of the controlling apparatus, the
compound solenoid moves an iron plunger back and forth, which in
turn makes contact through the armature of a small motor, causing it
2,612
HAWKINS ELECTRICITY
to rotate backward or for-
ward, cutting in or out a
field rheostat as may be
required to r^;ulate the
dynamo voltage. A lamp
resistance is also inserted
in each lamp circuit by
this motor when the dy-
namo becomes operative.
The motor serves also to
dose the djrnamo circuit
when the critical speed is
attained, thus an auto-
matic switch is not re-
quired.
In this r^ulator the
motor runs only when
r^ulation is necessary, so
that a minimum wear on
moving parts is obtained.
Due to the series coil of
the regulator being placed
in the battery circuit, the
batteries will be charged
entirely irrespective of
whether or not the lamps
are lit, so that, though the
lamp resistance be in cir-
cuit, the rise in chai'ging
voltage of the battery
will cause a proportionate
rise in voltage at tiie
lamps.
This could be lar^y
eliminated by a slight
modification of the r^;u-
lator solenoid, if anot£er
series coil were added to
the solenoid and this placed
in the lamp circuit so that
when the lamps are turned
on the current through
this coil will create a mag-
netic flux which wfll
largely replace that of
the battery charging cur-
rent.
This would cause a
o
ELECTRIC RAILWAYS
2,613
large decrease in the battery current when all the lamps are turned on,
and woiiild accordingly require that the charging be done largely during
the day. This in many cases would be a serious disadvantage, but when
installed on a car making at least a part of its run dunng the day
it might be made to operate satisfactorily.
Car Heating. — This may be accomplished by means of stoves,
hot water heaters and electric heaters. Systems using either
stove or hot water heaters are undoubtedly cheaper than those
employing electric heaters.
VlG. 8,680. — Section through car seat, showing location of panel heater of the system snown
in fig. 8,679.
The amotmt of power consumed by electric heaters naturally
varies with the climatic condition, but for cars ranging from
24 to 34 feet in length the power consumption for average and
severe weather conditions varies from 5 to 7 kilowatts, respec-
tively, so that the electric heater loads on both street railway
and interurban systems compose a very large part of the total
energy consumed. It is well known that on many well equipped
electric railway systems, the amount of power consumed in
2,614
HAWKINS ELECTRICITY
heating and lighting the cars dtiring very cold weather exceeds
20 per cent, of the power supplied to propel them. Both stove
and hot water systems however possess several disadvantages.
They occupy useful space, require special attention, and intro-
duce dust smoke and dirt into the car.
In the case of the stove, the heat is principally developed
in the upper part of the car, leaving the air near the floor com-
paratively cold. Furthermore, in the case of cars used for
Fig. 3,681. — Type of electric heater suitable for installation under cross seats of car.
heavy city service, where vestibules are not used and the cars
are not run as frequently in one direction as the other, it is
practically impossible to heat them by any other system than
that of electric heaters.
Ques. Describe an electric heater.
Ans. An electric heater consists of a resistance in the form
of a coil of wire, usually of galvanized iron, wrapped in the form
a close spiral around a porcelain tube. o
m
ELECTRIC RAILWAYS 2,615
Usually, two such coils are mounted in a
metallic case as shown by fig. 3,679, and the
entire arrangement secured to the risers under
the seat as ^own, fig. 3,680.
'Oil Ques. What important point should
s|| be considered in the design of electric
JsC heaters?
||| Ans. Special provision should be made
'g^l to secure good circulation of air arotind
.pjg the resistance coils so as to transfer the
•^Ij heat from their radiating surfaces as rap-
g|| idly as possible into the space to be
s£% heated.
S g « Unless this arrangement be efifective, the
P |J heat given out will not be uniform, and a
+j "9 a large amount is apt to be lost through the back
I S'l of the casing. Furthermore, if the heaters be
us^ installed too near the edges of the seats, they
•§ g Q are liable to become mt&ed by the clothing
Jj^ of the passengers resting against the perfo-
.*§ g§ rated front of the heater case, thus arresting
8 ° i the air circulation, and causing the tempera-
i I » ture of the coils to rise to a degree sufl&dent
^^'^ to scorch the clothes, or to set fire to the
p1 3 woodwork of the car.
II s| Ques. How may the amount of heat
I p. g furnished by six single coil heaters be
is|§ varied?
Illl Ans. This may be done by means of a
Jjg'ta temperattu-e regulating switch.
gS'S'S Usually, this switch has fiVe positions. "When
j> J feS it is turned to the first position all the heaters
'••3 ail ^® connected in series between the trolley
§1*^ I and the track, the resistance in the heater dr-
eoJSj'i ^* is greatest, and consequently the heat
t5 radiated is least. When the switdi is turned
£ to the fifth position the heaters are connected
2,616 HAWKINS ELECTRICITY
in three parallel groups of two each, the maximum current is allowed
to pass through them, consequently the greatest amoimt of heat is
obtained. In the intermediate position of the switch, one or more of
the heaters are entirely cut out of circuit at will.
Track Construction for Electric Railways. — This varies
in design according to the character of the service and the trac-
tion system or method of power transmission employed.
mdmm mmmm mmmkn
I — wwwpwwi mmm wmfrntn
— mmmm- mmm — ^-mimmr^
^^eRouND — ' — wmim mmmm wimm^
Fig. 3>68S. — Wiring diagram of six heater equipment with type of heater shown in fig. 3,682.
Three variations in the amount of heat furnished may be obtained with this arrangement,
a suitable switch being provided by means of which either the smaller, or the larger coils
(see fig. 3,682), or all the heaters may be turned on at a time, or both sets of coil may be
operated at the same time.
The track construction for overhead trolley line systems
differs but little from other forms of railway construction, with
the exception of the bonding of the rail joints. With the use of
a grotmd return this is absolutely necessary to secure a con-
tinuous metallic path, thereby reducing the resistance which
would otherwise be introduced into the circuit.
Rail bonding is acxxnnplished by a variety of method. A oc»iuiion
form of rail bond used on trolley roads consists of a copper wire, whidi
ELECTRIC RAILWAYS
2,617
is passed twice through holes in;
the rail on each side of a fish
plate. At intervals the wire is led
directly across the track and at-
tached to the other rail, thu&
^ectively connecting the two rails-
to|;ether. Copper wedges are
driven into the holes in the rails
to effectually wedge the wire
against the rails. In the case of
doubletradc roads both tracks are
connected together in a similar
manner. This type of bond is com-
monly known as the" solid wire
bond, and when made in short
lengths breaks easily from track
vibration.
Ques. Describe the cable
bond.
Ans. The cable bond con-
sists of a bundle of copper wiresi
the ends of which are soldered
together and to terminals by
which it is attached to the rails
outside the fish plates. In some-
forms, the terminals have holes
drilled through the center of the-
shanks. These shanks are m-^
serted in the holes in the rails
and then expanded to a tight
fit therewith by beveled steel
pins driven into the holes.
Ques. Describe the ribbon
bond.
Ans. The ribbon bond con-
sists of a series of lamination
or thin strips of copper, about
2,618
HAWKINS ELECTRICITY
•023 inch thick, bent into various forms to give the greatest
possible degree of flexibility.
In the soldered type of ribbon bond, the ends of the laminations arc
separately timed, clamped together, and after being dipped in solder
or welded together, are c»vered with wrappers. The terminals thus
formed may be soldered to the head of the rail, or to the base of the j:aiL
Ques. What advantages are claimed for the T form
of rail, as compared with the girder or grooved rail?
CROSS SECTION
-li(^-0- = M JSAMO
Pigs. 8,688 to 3,691.— Cross sections and plans of typical car tracks with T rails in paved
street. The height of the rail used in any particular case will depend on the chracter ol
the paving. In some cases it might be necessary to use an excessively heavy standard laU
paving stnp 8 ft. wide will vary t ..
to the cost of material, weight of rail, wages and character of labor, etc.
Ans. 1, It is designed on better mechanical lines, and there
is not eccentric loading as in the grooved rail, 2, there is not
excessive waste of material in rails required for heavy traffic
and large wheel flanges. Grooved rail weighing from 125 to
160 lbs. per yard, are being used in many cities, where T-rail
ELECTRIC RAILWAYS
2,619
weighing 80 to 90 lbs. per yard, would be amply sufficient,
3, the flangeway is always ready for an increase in the size of
wheel flanges of local cars, or for the large wheel flanges of high
speed interurban cars, 4, the T rail is not as noisy as the girder
or grooved rail, 5, it has a longer life than any other type of
rail, particularly at the joints which are the vital points in
any rail, and 6, it is cheaper, more easily handled, and does not
reqtiire the use of high priced shop curves.
Pig. 3,692. — Section of underground conduit showing handhole at each insulator; these are
located 16 feet apart, manholes being provided every 150 ft.
Figs. 3,688 to 3,691 show cross sections and plans of typical track
construction with high T rails in paved streets.
Conduit or Underground Trolley Systems. — The kind
of construction employed largely depends upon the local con-
ditions and requirements. In general it consists of a series of
2,620
HAWKINS ELECTRICITY
iron yoke embedded in a concrete sub-stirface structure which
forms the conduit from the imderground conductors. The
type of yoke used in the construction of the track of the Lenox
Avenue line of the Metropolitan Street Railway Company of
New York City, is shown by fig. 3,693.
^ B '^ A
//////////y.'y/////'/'/////////A
Pig. 8,008. — Yoke construction for conduit or underground trolley, as installed on Metropolitan
Railwairs, New York City. These yokes were placed 6 feet apart m ah excavation made
through the street. The track rails A, A, and the slot rails B, B, were then laid on the
yolcM. and the ties C, C, inserted. The whole stnicture was then blocked up, surfaced and
fined, and constituted the track construction. Tlie conductors consist of two channel
beams, D, D, placed 6 inches apart and supported by insulators E, E, at each yoke. The
contact rail jomts are bonded in a manner somewhat similar to ordinary rail bonding, and
from a complete metallic circuit having a pressure of 600 volts between the conductors.
The current from these conductors passes through the slot or opening between the slot rails
and extends into the conduit to a distance sufflcient to bring the plow contacts or shoes
Pf against the conductors. The spring G, tends to keep the shoes normally about
8 mches apart, so that when they are pressed into the 6 inch space between the conductors,
they maintain a firm sliding contact with the latter. The yokes used on some of the lines
constructed later are practically the same, but T iron conductors are used instead of .the
channel beams. In oraer to provide of expansion and contraction the center of each section
of rail is fastened solidly to an insulator at that point, and the ends of each rail are slotted
and bonded with a flexible bond. Hand hole provided with iron covers are placed about
15 feet apart directly over the insulators. The manholes are placed about loO feet apart,
and usually between the traclra. Arrangements are made at these points to drain the
conduit into the sewers. The bottom of the conduit is given a minimum grade of 2 inches
to 100 feet, so as to insure proper drainage on sections of level track. The contact rails
are treated like a double trolley wire, and the feeders and mains are laid in underground
conduits. This system is so expensive to install that its use is limited to only a few of the
largest cities where for various reasons the use of the overhead trolley is objectionable and
prohibited. ^ - , ^
ELECTRIC RAILWA YS
2,621
Third Rail Construction. — There are two types of third
rail in general use:
1. Exposed type;
2. Protected type { ^^C
contact;
contact.
The third rail is usually placed outside the rack rails on insulators
mounted on the ties, and is either entirely exposed as on the lines of the
MarJiattan Elevated Railway, or protected by wooden shields carried
NSUUTDfi?
Fig. 3,694. — Cross section showing cartruck of protected top contact third rail.
by yokes from the rail itself, as on the lines of the Interborough Rapid
Transit Company of New York, as shown in fig. 3,694. These represent
the simplest type of third rail construction, but while they give good
service with liie special condition under which thejr are used, it has
been foimd that in many ways the top contact rail is not suitable for
interurban railway systems or for the electrification of existing steam
railroads. The prinapal objection is that as its lower part is only about
four inches above the ties, it cannot be effectively protected from
accumulations of snow, ice, dirt, etc., which tend to cause serious
ground and excessive leakage. This objection is almost entirely
2,622
HAWKINS ELECTRICITY
eliminatedln the protected third rail system which has been adopted on
the tracks of the New York Central Railway, the Philadelphia Rapid
Transit system, and a number of other roads, as shown in figs. 3,695
to 3,697.
Trolley Line Construction. — The various methods of
trolley line construction may be divided Into two classes
FIKjS. 3,695 to 3,697. — Details of protected bottom contact third rail. It con^ta of a series of
iron bracket carried on ties, to the tongued vertical face of which are clamped non-charring
moisture proof insulating blocks which loosely embrace the head of the rail. Intermediate
between the insulators the rail carries an insulating sheathing which embraces the head
and reaches down nearly to the bottom face of the rail, but extends outward from the web
so as to form a petticoat j>rotection against snow and sleet. The ()Osition of the rail depends
upon the clearance requirements. To meet the ordinary trunk Ime conditions, the bracket
height is made such that the under-contact surface of the third rail is 2% mches above
the surface of the track rail and the center of the rail is 27 >^ inches from the rail gauge line.
With this arrangement the height of the third rail above the ties and ballast is about 5
inches more than^it would be in the case of ordinary top contact rail construction. On
crossings, the horizontally extending slipper shoe, which is normally pressed upwards by
the spring, lifts and clears the track rail by a safe margin.
according to the method employed for suspending the trolley wire,
1. Bracket construction;
2. Spaa wire construction. Digitized by Google
ELECTRIC RAILWAYS
2,623
In both classes, the trolley wire may be supported either
directly from the insulators carried by the brackets or spans,
or from a steel cable or messenger cable which in turn is sup-
ported by insulators carried by the brackets or spans. The
former is the old and familiar method of construction employed
TROLLEY WIB£
Fig. 8,698. — Eleven point bracket catenary construction for single track. The bracket type of
construction is the cheapest and is the one generally used for ordinary interurban service.
On double track lines the poles carrying the brackets are placed on each side of the right of
way.
for direct current lines, and the latter is the new method com-
monly known as catenary line construction.
Although the catenary type of construction has been developed to
meet conditions incidental to the distribution of high tension alter-
nating current for the operation of interurban electric railways, the
marked mechanical improvement obtained both in the strength and
durability of the overhead structure, and in the maintenance of a
2,624
HAWKINS ELECTRICITY
straight trolley wire» at a cost less than that of the older type, tend
to nuike the catenary the standard practice, not only for alternating
current work, but also for low and high voltage direct current work,
even on lines of limited extent.
The catenary type of construction was originally designed by. the
Westinghouse Company in connection with their single phase railway
equipment designed for operation with line pressures from 3,300 to
11,000 volts.
There are two general classes of catenary construction: the single
catenary, and the double catenary. In both of these the prindpa]
object aimed at is the maintenance of the trolley wire at a constant
distance from the top of the rails.
Fig. 3,609. — ^Anchorage for double track span wire catenary construction. The span wire
construction is more expensive than the bracket construction and not as satisfactory, al
it requires longer poles and produces a more severe loading of the poles, than bntdcet
suspension. It is used only where the local conditions make its use absolutely necessary
as m the case of section of track passing through very wide streets or roadwajrs of country
lawns.
Ques. How is the wire supported in the single catenary
construction?
Ans. By a single messenger cable carried by the bracketSi
spans, or bridges. Digitized by Goog
ELECTRIC RAILWA YS
2,625
^ Fig. 3,608, shows an eacample of 11 point bracket catenary construc-
tion for a single track line. Fig. 3,o99, shows the anchorage, for a
double track span wire catenary as designed by the General Electric
Co. Fig. 3,700, shows a bridge supported catenary for a double track Hne.
Ques. What strain is brou^t on the trolley wire in
catenary construction?
Ac. 8,700. — ^Bridge type single catenary construction for double track toad. In.this arran^
ment the trolley wire is suspended from a messenger cable supported on bridges spanmg
the tracks and supported bjr towers on each side. This tyi>e of construction is seldom used
for anything but the heaviest class of service, euch as electrified steam railroads, and
substantial mterurban roads handling heavy frei^t traffic as well as heavy paf senger traffic.
Ans. The trolley wire has to support its own weight, only,
iCL the short spans between the hangers.
Accordingly, it can be selected with r^ard to its electrical canying
capacity and regardless of its tensile strength; but in order to keep the
deflection in these spans at a minimum, the troUe^ wire is usually
strung with a tension of about 1,000 lbs., thereby serving also to stiffen
the structure and prevent the trolley pushing it over to one sLdet
2,626
HAWKINS ELECTRICITY
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ELECTRIC RAILWAYS
2,627
Pig. 3,708. — Single catenary curve construction, tn iocating the bracket arms on poles and
the poles on curves, the eflfect of super-elevation and the lateral overhang of the cars ox
locomotives must be allowed for, aa well as the position of the current collector. Anchof
spans should be placed at the ends of curves and at frequent mtervals on tangents.
Figs. 3,709 to 3,711. — Detail of bracket arm with steady strain. The bracket arm is con*
structed of a 3 inch I-beam, the outer end of which is bent upward, to prevent the mes-
senger cable falling if it should happen to become detached from the insulator. The
I-beam is secured to the pole by means of a tension rod and steel angles. The regular
distance from the center of the track to the pole is 7 ft., 4 ins., which is sufficient to provide
ample clearance on tangent for all types of CQuipment. It may be found necessary, how-
ever, to increase this distance on sharp curves, to allow for the overhang of large cars, and the
bracket arm can be readily lengthened to cars for any degree of super-elevation. The
steady strain and insulator are secured to the bracket arm by hook bolts and malleable iron
clamps so that they can be shifted to stagger the trolley wire, a maximum throw of 8J^
inches being possible on each side of the center line. This staggering is essential where
pantagraph or bow trolleys are used, but may be omitted on Imes using wheel trolleys.
The steady strains are placed upon every fourth or sixth bracket arm on tangents, and
upon every bracket arm on curves. The msulators which support the messenger cable are
of porcelam with brown glaze, and are proportioned for the operating Ime voltage. The
form of the vital points in high voltage trolley line construction here shown is the skirt
type; it is secured to the bracket arm by a malleable iron clamp and hook bolt, as shown
at A, fig. 3,711. The steady strain which prevents the trolley wire swinging laterally,
consists of treated hardwood rod with substantial end sockets, one end being adopted to
clamp the trolley wire, and the other secured either toihe bracket arm for pressures up
to 6,600 volts, as shown at B, or to an insulator and braclcet, for higher pressures, as shown
atC,fig.3,709 ^ ^
' 2,628
HAWKINS ELECTRICITY
Ques. What kind of messenger cable is used?
Ans. The inessenger, or supporting cable is usually a J6
inch seven wire galvanized steel strand. Bessemer steel is used
for spans up to a maximum of 120 feet, and Siemen's-Martin
steel for longer spans.
OCTAtLOFAHCNORPOIHT
Pig. 3,712. — Catenary construction at anchor span. In erecting, the clamp used for the t
Bcnger cable is placed at the center of a span , so as to grip both the messenger cable and the
diagonal anchor cable. Two pull off hangers are placed each side of the messenger anchor
clamp, replacing the ordinary hangers, and a short piece of strand wire is used to tie these
pull on hangers to each other and the anchor clamp. The anchor wire is pulled between a
pole and an anchor pole on the opposite side of the track, both of which are guyed, and tiie
anchor cable is dead ended on the strain insulators.
The messenger cable should be of sufficient strength to support the
span tander the most severe weather conditions. The cable is run out
in long lengths and then pulled up to a tmiform tension in all spans.
Ques. In erection how are the trolley wire and met-
senger cable installed ? Digitized by Google
ELECTRIC RAILWAYS
2,629
Ans. It is usually found convenient to run out the trolley
wire and messenger cable together, laying them on the bracket
arms for support until the messenger cable can be pulled up
and tied to the insulators; the trolley wire is then stretched
and hung. Tower line cars or wagons of the tisual design are
used in this work.
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Pig. 3J13. — ^Trolley deflector construction at switch. Thm method of eonatruetion employed
at turnouts and sidings depends upon the type of current collector used. For the wheel
trolley, the sidi^ trolley wire is brought to the main line at the switch, and then carried
down the main Ime, parallel to and at a distance of 12 inches from the main line trolley
wire, to a distance of about 200 feet. For the pantagraph trolley, a so called deflector set
Is used to prevent the trolley becoming caught. The layout of the poles and line and the
construction of the deflector are here uiown. The deflector consists of number of trolley
wires held in place by ordinary trolle:^ ears which are bolted to cross bars spaced about
8 feet apart and supported by, the main line and siding trolley wires. The ends of these
rods are raised about 4 or 5 inches above the siding and the main line trolli^ wires so
that no possibility of the ends of the pantagraph beconung caught in them, ^ The siding trolley
wise is carried over that ot the main line to an anchorage on m farther side.
2,630
HAWKINS ELECTRICITY
Signal Apparatus. — ^The selection of proper signal apparatus
for an electric railway is governed by many conditions: whether
the system be single or double track, city, suburban, or inter-
urban; whether the track be straight, or have many curves, be
level, or of many grades; whether direct or alternating current
be used for train propulsion, etc. There are two general classes
of railway signal:
Pig. 3,714. — ^Pour track double catenary construction with bridge supports. In this eorutruD^
tion, the trolley wire is carried by two messenger cables supported on bridge of substantial
construction spaning the tracks at intervals of 300 feet or more, as here shown. This
type of construction represents the highest development of the art of line construction for
electric railways. It produces a very rigid structure which is not subject to undue lateral
vibration for wind pressure, but is very flexible with regard to vertical pressures ex-
erted by the current collectors. Owing to its great cost, however, it is used only in
the electrification of lines of the heaviest class.
1. Block system;
2. Interlocking system.
Block signaling has to do with keeping trains which are
mnning on the same track, at a proper distance apart.
ELECTRIC RAILWAYS
2,631
Inter-locking signaling is for the control of trains over tracks
which intersect at points of crossing or divergence, and has for
its object the prevention of conflicting movements, the proper
routing of trains, and the insurance that the movable parts of
the track are in their right positions before the signals govern-
ing movement over them can be made to give a proceed indi-
cation.
TROLLLY WIRE.
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SWITCH I AMR^
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WEATHERPROOF INSULATION
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Pig. 3,716. — ^Automatic block signal system. This system comprises a signal box with white
and red lights, located at the end of each block provided with corresponding red and
white semaphore discs: a set of trolley switches by means of which the signal boxes are
automatically operatai.
Block signals may be classed as
1. Non-automatic;
a. Non-cx)ntrolled manually operated;
h. Controlled manually operated;
c. Staff system.
2. Automatic.
Digitized
by Google
2,632
HAWKINS ELECTRICITY
Ques. Where are non-controUed manually operated
signals used?
Ans. At passenger stations, junctions or other convenient
points where operators are convenient in connection with the
telephone or telegraph blocks.
They are put in the proceed position to permit a train to enter the
next block when information has been received by the operator from
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Pig. 3,716. — Corresponding a^ects of semaphore and {position light signals with their in-
dications. Early in 1014 Dr. Churchill of the Coming Glass Company, wUle working
on some of the electric headlight troubles of the western railroads, discovered that it
was possible to secure verv long range from a small light source located in the exact focal
point of a small wide angle lens, and in talking the matter over with A. H. Rudd, signal
engineer of the Pennsylvania, it was seen to be altogether practicable to combine uese
■mall separate units into rows of lights which would have the effect of the present sema-
phore arm and would do away with the color scheme altc^ether. Thus was evolved
the position light signal, which has now been covered by various patent applications.
It was, of course, a long way from the conception of the idea to the perfection of the
design, and it was not tmtil the summer of 1914 that the signal was consic^red satisfaotofy
enough to adopt. The principal experiments were conducted at Wayne and later at Paoh.
the next station in the direction of traffic that the preceding train has
passed out of the block. They are placed in the stop position on the
passage of the train.
Ques. What is the objection to non-controlled manu-
ally operated signals?
Ans. Misunderstandings, and the dangers resulting therefrom.
ELECTRIC RAILWAYS
2,633
Ques. What provision is made in controlled manually
operated signals?
Ans. Electric locks are applied to the levers operating the
manual signals.
The locks are inckided in circuits running between block stations,
and are so arranged that when an operator wishes to place a signal in
the proceed position he has first to ask (by bell sijgnal or otherwise)
for an unlock from the next station in the direction of traffic, and
cooperate with the operator at that station in the proper manipulatioii
of the circuit to get his unlock.
STATIOM Y H
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AUTDMATIC
OPERATOR
' CUTOUT ^
KEY
STAFF mSTRUMEMT
SWITCHBOARD
FI0.3J17. — ^Wiring diagram of atttomatic operator system. By usmg the automatic operator
(xmnected as shown, it is possible to operate a staff block without an operator at either
station. Twenty dry cells of battery are generally used to ftimish current for the operatioa
of each automatic operator. When current is passed through the line the armature it
rotated in a direction to cause it to lift the weight on which the normally closed contact it
fixed. When current through the line is broken this weight causes the armature to rotate
in the opposite direction a sufficient distance to close the other contact and cut in a local
battery. Current from this battery passes through a pair of coil holding the armature
in this position and releases the staff at opposite ends of the block. When the circuit it
again broken, battery is cut off the line.
Ques. Describe the stafE system.
Ans. In this system the possession of a small metal cylinder,
or "staff" gives the engineer permission to run through a block.
These staffs are normally in one or the other of a pair of instruxneol
call staff instruments, one of a pair being at eadbn end of a blc^ OcS^
2,634
HAWKINS ELECTRICITY
one staff can be taken from a pair of instrument at a time because of
their locking features, controlled by circuits between the instruments,
requiring the co-operation of two people, one at each instrmnent, to
abstract a staff. Until this staff is replaced in one or the other instru*
ment, no other staff can be withdrawn.
Ques. What provision must be made for tracks used
for block signal circuits?
Ans. They must be insulated from the ground by fibre,
so that the electric current will not dissipate into the ground.
FiC 8,718. — Method of applying bond wires to two butting rail ends. Two wires, whidi aie
usually No. 8 B. W. G. galvanized E. B. B. iron, are wunted across the fish plate, con-
nection being made by means of channel pins.
Where rails are joined they must have extra electrical connections,
that is, be bonded so as to overcome the open break between the rails.
The block sections of track must be insulated from the rest of the
track at these terminals as shown in fig. 3,710.
Bell and Relay Circuits. — ^For the operation of bells or
relays, there is the two rail circuit and the single rail circuit.
The rail or track circuit is that which is affected by the presence
of a train within a block. Where the railroad is equipped for
third rail electrical propulsion the single rail system is gen-
erally used; when steam engines are employed the double
track system is used. Digitized by Google
ELECTRIC RAILWAYS
2,635
Railway Signals. — These consist of colored lights, colored
flags or by metal signal banners. Some roads use a green signal
for precaution while others use a yellow signal. Red is the-
danger signal.
Pig. 3,719. — Insulated rail joint at end of a block section of track. A type used for heavy maia
line traffic. Insulating fibre is placed between the rail ends and clamped between the rait
and the joint plates and insulated bushings are placed around the bolts.
miULATlOM:,
Pig. 3,720. — Simple method of connecting a relay between insulated joints of track and forming:
a block signal, the circuit being closed by the train as it passes over that section of track.
Ques. Name three kinds of signals in general use.
Ans. Caution, stop, and proceed signals.
Distant block signals are sometimes used in connection with home
block signals to signify the approach of a train.
Ques. What kind of signals are used during the day
and at night?
Ans. Flags or metal signals during the day and lights of
various color at night. o
2.636
HAWKINS ELECTRICITY
Disc signals are displayed by movable shutters or discs in front of a
fixed background; semaphore signals, by the position of a movable
1 MILE
Pig. 8,721. — Simple track circuit whereby a signal ia operated by a train in a block.
PiQS. 3,722 and 3,723. — ^Universal train annunciator. Fig. 3.722 ihowa annunciator equi;^
with manual reset, and fig. 3,723, wfth magnetic reset. The indications di^ligred by eil
type are shown in figs. 3,724 to 3,720. ^
ELECTRIC RAILWAYS
2,637
ann in a plane at right angles to the track and mounted on a high pole.
The semaphore arms of distant ^gpals have notched ends while the
home signals have straight ends. When a home semaphore signal is up
it means to stop; danger ahead. When a distant semaphore signal is
up it means to proceed with caution and the next home station signal
will indicate if the block be clear. Whether or not a relay be used in
the track circuit a bell is generally rung. At distant crossmgs only the
bell is used, but near stations the rday is used to not only ring a bell
but to throw a home signal.
Pigs. 3,724 to 3,726. — Diagrams showing operation of three position universal annunciator.
Fig. 3,724» normal position: card displaying clear, local bell contacts open; fig. 3,725,
train in circuit position: card showing train, local bell contacts closed; fig. 3,726, restored
Position — showing red color — ^this is done while train is on circuit: local bell contacts open.
The bell works on open circuit; the spring contacts being closed only when the train is on
the track. If it be desired to stop the ringing of this bell and reset the annunciator while the
train is still in the block, the lever is pulled, down and the indicator shows a red color signal
which remains in view until the train has left the block, when it automatically restores to
the position showing clear, as in fig. 3,726.
Relays for Railway Signals.— There are four kinds of relay
used for signaling; these are classed as
1. Polarized;
2. Neutral;
3. Interlocking;
4. Time.
These are shown in the accompanjKng illustrations. Polarized relays
and nejitral relays havp much tne same kind of electromagnets as are
used in the construction of crossing bells and are used in the simplest
2,638
HAWKINS ELECTRICITY
Pig. 3,727. — Polarized relay, wall type, with four front and four back neutral contacts and two
front and two back polar contacts. The armature of this relay is itself a permanent
nmgnet and swings back and forth to either pole of the electromagnet as the current
attracts and repels it or whenever the polarity of the relay magnet changes.
Fig. 3,728. — Slow release neutral relay with six front and back contacts. This relay is e ., . .
with extra large magnets having the slow release feature added as sometimes required' by
Solarized wireless rail circuits when it is necessary to prevent the opening of signal circuits
uring the reversal of current through the polarized track relay. This slow release relay is
also used when line wire circuits controlling annunciators or indicators are used with tnck
instruments or short rail sections to prevent the circuit being opened or closed with the
passing of each car. - ^^
ELECTRIC RAILWAYS
2,639
bell circuits. Interlcx^ng relay magnets are similar to double polarized
or neutral relay magnets. Time relay magnets consist of a smgle coil
of wire.
Signal Circuits. — On electric railways equipped with a
trolley or thdrd rail alternating ctirrent supply, direct current
must be used to operate the signals and the apparatus de-
scribed will work well on a single rail circuit, but where the road
Pig. 3,729. — Glass enclosed interlocking relay; wall type with interlocking contact. Inter-
locking relays are in reality a combination of two relays in one and are used in connection
with two track circuits. The entire operation is actuated by gravity and without springs.
Pig. 3,734 shows the interlocking relay connected to the track of an unoccupied block;
fig, 3,735 shows the condition of the relay as the train enters it; fig. 3,736 shows the train
between the relay connections and fig. 3,737 shows the condition of the relay when the
train has passed into a second block
is equipped with a trolley or third rail direct current supply,
alternating current must he used to operate the signals on a single
rail circuit.
The trolley railway is in this case supplied by direct current which
is fed by the trolley \vire. After passing through the car motors it
passes to the grounded rails and thence back to^ the power house from
whence it came. ^
2,640
HAWKINS ELECtRICITY
One part of the track is insulated from the rest of it between the
joints in two places, which part represents the terminals of a block.
The other track remains grounded and uninsulated, and to it is
attached one end of an alternating current relay winding, the other
end being connected to the insulated SxJction. This relay, which is
generally known to signalmen as the polyphase relay is connected
between the insulated and the uninsulated tracks as is also the secoikl-
ary winding of an alternating current transformer. The primary coil
of this transformer is connected to an alternator. A second smaller
transformer has one winding connected across the alternator mains
and the other winding connected to the signal circuit.
Pig. 3,730. — A croBsing l)ell circuit showing application of Chicago time relay (ihown in fig.
3,731). There is a wide variety of application for this type ox relay, including wire'oper-
ating crossing bells, locking and release circuits.
Across the alternating circuit relay ^dnding is shunted, or coanected
in parallel, a low resistance reactance coil for the purpose of absorbing
some of the alternating current. The relay works on closed drcuit.
When there is no train in the block the drop in voltage of the direct
propulsion ciurent is divided between the two insulated ends of trade
in proportion to the resistance of the apparatus connected across the
track, there being practically no drop of voltage in the block raiL Sudi
it the case also when a train is in the middle of the block. However*
ELECTRIC RAILWAYS
2,641
when a train is just entering the block near the relay both rails are at
the same pressure at that point because they are connected by the
wheels ana axles, which cuts out the relay and renders it inoperative,
allowing the alternating current to flow full into the danger signal lamp.
The drop in direct current is then at the transformer which is very
unfavorable for the cperation of the transformer, which then receives
the maximum direct current from the track while delivering alternating
cttrrent to work the relay.
Pig. 3^731. — ^Rear view of Chicago time relay. A time relay is uaed when electrically controlled
time signals are required, such as linewire operated crossing bells. When current is sent into
the high resistance of the releasing magnet the armature is attracted, which allows the pen-
dulum to swing toward the other magnet of the relay. Then it is automatically pushed back
again and so is kept oscillating back and forth like we pendulum of an electrically operated
clock. This may continue tor a minute or a minute and a half, according to how the
mechanism is set.
When the train is at the other end of the block and about to leave it,
the transformer receives no direct cuirrent and can deliver a maximum
of alternating current and at the same time the relay receives direct
current and is properly rendered inoperative but the danger signal
lamp glows bright.
Thv& single rail alternating cturent signal circuit is used with marked
success in the New York subway.
The automatic block signals, the automatic train stops and the
interlocking switches there are of the electro-pneumatic type.
2,642
HAWKINS ELECTRICITY
The track block relays control circuits which in tura control mag-
netically operated pin valves governing the admission of air to the
cylinders which actuate the signals and train stops.
It is possible to use the double rail return system for signaling where
the railroad uses direct current for propulsion and alternating current
for signal operation, by the use of balanced inductive bonds connected
across the rail insulations at the ends of the blocks. This double rail
•circuit is a feature of the signaling operation of the New York, New
Haven and Hartford. Railroad.
In the New York subway tunnel, home signals consist of a series of
T^ulated lights whose source of electrical supply is governed by the
action of the track circuit.
Pig, 3,732. — A method of frog bonding. There are many good foremen in charge of construc-
tion forces bonding frogs, but there are no two who have the same ideas as to the best
method. It is the custom to put the holes in the rail where it is most convenient and to
put the channel pins on the side on which the bond wire is put through the hole. This
IS done because it is impossible to drive in the pin securely where the rail leads are close
tos^ether. The man driving the pins often bends the wire away from the pin so as not to
stnke it. To get around this method drill 4 instead of 2 holes and put the bond wire
through the hole and then bend back with a loop, and bond from the outside; this does
away^ with all chances of striking the bond wire. In the majority of cases copper clad
wire is used to bond in frogs, which is not difficult to bend, as shown. In bonding
around the frog it is advisable to twist the wires and stai>les about 6 inches from the raiL
This leaves the wire so the section man does not interfere with it when he draws
Spikes. At the points A, B, and C it would be difficult to drive the pins if not put in as
escribed above.
The home relay control circuit is fed from a secondar}r track relay
circuit ahead, to and through a secondary track relay circuit at the
place where it energizes the home relay.
A train passing into the block governed by this signal causes the
track closed circuit to open and the home danger signal to show.
The distant signal circuits are so arranged that when the distant
relay is energized a circuit is completed to the home relay which throws
a caution signal - o
ELECTRIC RAILWAYS
2,643
Electric Interlocking. — ^When a switch lever in a tower is
manually moved from normal to reverse, the locking between
it and the signal lever controlling the governing movements
of the signal over the switch reversed is instantly released,
but when electric power is used for operating the switches, the
movement of the lever merely turns on the power and it is not
safe to assume that the switch follows the movement of the
lever because the circuit may be open at any place. For this
F!lOi 8,783. — Interlocking relay for alternating current. The contact springs are glass enclosed.
Eadb armature may be equipped with as many as three extra front and back contacts in
addition to interlocking contacts, of which there may be as many as four. It is an im-
proved type of polyphase relay.
reason the lever movement is divided into two parts: 1, the move-
ment which causes the closing of the operating circuit, and 2,
the movement which causes the interlocking of other levers.
The first important step toward the development of a prac-
tical system of electric interlocking was when a means was
discovered for making use of a current of electricity which
could be generated by the switch operating motor itself.
2,644
BAWKINS ELECTRICITY
TBAIM
Pigs. 3,734 to S.TSr.—Dia^rammatic sketches illustrating fhe interlocking feature of umveaal
crossing bell relay. Pig. 3.734 track circuit A B and B C unoccupied, bell circuit open;
fig. 3,735 train has entered track circuit. A B relav magnet L. De-enenpsed armature
Lrl causes contact finger L-2 to make contact with M bell circuit closed; fig, 3,736, train ia
track circuit A B and B C (at crossing) relay magnet R de-energized contact finger R-S
resting on I/-2 bell circuit closed; figT3,737, train m track circuit B C relay magnet L
eneivized contact finger R-2 resting on L-2 bell drccdt open. When train passes oat of
trade circuit B C all parts normal as in fig. 8«734, operation similar in either direction.
ELECTRIC RAILWA YS
2.645
Fis* 3,738. — Advmnced block distant signal. In ttpvralion wBen ttie towerman pulls a
lever numbered tbf: same as the diistant signal he desires to operate, he o^nnpkte* a dxctut
btitweea the two ^pris^s^ which causes the d^tant $igo$X blade to dear.
PlO. 8.73^*— Distant signal and teptattr circuit. Here, through ale verconncction, when thele\rer
ispulle-il out in the to«*er, current Is allowed to flow to and coniplete a drcuit through a
contact, j^pririK operated by the aiRtial mci hzinism. As GCwjin as the distant hbde clears,
according to this circuit, s repeater located in the tower k de-enei^ized and dtop& its
armature, which shows the position of the blade whose action governs its source of enersy.
Pig, 8,740.--Diagram illustrating deetrfa mterlockiVig . A s-.'Aich and lock tiiovenipnt is driven
byaoitut;^ (.urn^iK nv'^r. I'f^ shun •..,< : .. , j.- ,.. i,i ,:-. ted ^'y 'i nii^i^i^tLc cl'itch to an
extension working a cam drum which operates the switch and lock. When the drum is
revolved by the motor, first the lock rod and then the switch move in proper operation.
After the switch has been moved against the stock rail it is automatically locked and a
knife switch throws open the control circuits and closes the indication circuit. The auc-
tion of rotation for reversing the switch is controlled by a double field winding m the
motor, one part of which is cut out while the other is in circuit. c»
2,646
HAWKIN-S ELECTRfCITY
Blocks. — ^The length of blodc sections of any railroad will
vary anywhere from one to two miles. To secure a maximum
capacity for train movements the maximum distance required
for the stopping of any train on the road should first be decided.
There are various conditions to be considered in fixing the
length of block.
TELEPHONE LIME
saecTOR
UGHTNING ARRESTERS
QROUNO
RESISTAMCETOBALAMCE
STICK
RELAY
mS~$
CIRCUIT CONTROLLDl
ON SlOHAlT^
Fig. 3,741. — ^Train dispatcher's selector system. Thia Is uaed to indicate to the train engineer
whether he is to proceed on the main line or to take a side track. The indication may be
in the form of a disc, a light, a semaphore, or any prescribed signal. When the indicator
signal is turned from the normal to the reverse position a special "zmswer back'* device
is. also operated, which makes an audible noise and informs the dispatcher that the signal
has operated properly. This device is controlled by a commutator operating on the signed ,
mechanism in connection with an induction coil. To display a "take siding" signal the
dispatcher turns a switch or depresses a key which oi>erates the selector by closing the
normally open contacts marked C. The "stick relay" throws signal battery current into a
motor which operates the signal. To restore the signal to normal position the dispatcher
operates the selector in the reverse direction, which opens the contacts marked C. This
causes the "stick relay" to restore to normal position and throws a reverse signal back to the
dispatcher. This system is semi-automatic. ^ o
ELECTRIC RAILWAYS
2,647
Ques. What road conditions require long blocks?
Ans. Blocks should be longer on a descending grade than on
an up grade because it is more difl&cult to stop a train on a
descending grade.
Another feature involved is the curvature of the road or obstructions
to view, such as bridges. In every case the block represents, the space
between home signal, the distant signals acting only as repeaters
for the home signals and indicated by notched semaphores.
Fig. 3,742- — Inleraection of two double track lines, with their rcapeetive signals. If thsee
be aBtomatlc track retnys propter ly intereontiectedn they can bt readily arranged to
give the protection deBlred,. If they be Betal^automatlc* electric interlocking will be
introduced to prevent confijction of routes* ITius. when signal 3 is at clear, to allow a
south bound tr&in to pEiss, 2, and 4, must be locked In the nonnal or stop position
when electric locking 0t intetloddng is used and prevented moving to clear it the ordi-
nary automatk system be employed.
Man^ement. — This relates, not only to the necessary
conditions of operation and control, but also to the ntmierous
disorders and mishaps likely to be encountered. The motor-
man or repair man who possesses a thorough knowledge of the
construction and working principles of all the car mechan-
ism is well equipped to cope with the ordinary faults arising in
operation, especially when some practical experience is coupled
with the theoretical knowledge. byGoog
2,648
HAWKINS ELECTRICITY
On many large roads the motormen are expected to do nothing beyond
operating their cars and whenever trouble occurs to a car on the road
it is pu^ed in by the next car and the repair men at the bam make the
necessary repairs.
There are, however, many small roads where a knowledge of how to
remedy trouble is needed, and even on the large roads, the man who
understands his car can save many delays if he know how to intel-
ligently report troubles.
In enumerating many of Uhe troubles to which cars and motors are
subject, the reader should not think that, without practical experience,
by simplv icuiJIijg tJit^e Itnth, lie can manage a car as wdl as a man
hGME SE^lAPHORE,
WNiTE OR BLACK
jREEN -I
Vi^ 11 t?l5TAN-r SEMAPHORE
Pig. 3,743. — Standard home end diatant Etf^omphore eigtmla! Inoperaticm, until either blade
has reached a position approxtmately 30 degrees from the vertical it will indicate the same
as ttiDutrh at the full horizontal position. This i9 effected by using several spectacles,
each htld in place hy independent l>e?^l rings » ^maphores vary in length from 4 to 5
feet, about 4 ^-^ being rego-rded as stand iird.
who has been operating one for years. Practical experience is abso*
lutely necessary, but in connection with it the information here given
will De very helpful to the motorman.
A great deal must be learned by actual experience, and success in
economical operation on a car line depends partly on the watchfulness
of the motorman. While operating his controller he can readily detect
irr^ularities, first, by the way the motors take the current when the
controller is operated, and secondly when the car is imder way, by the
sound of the motors. - o
ELECTRIC RAILWA YS 2,649
The economy which can thus be accomplished lies in the fact that
loose bolts, a loose connection and the like are easily tightened. ^ These
are small troubles, caused by constant jarring of the car, which are
. easily attended to. However, if the car be not watched, bolts will be
lost, bearings wUl come loose, the armature revolving at a high rate of
speed may be rubbing against the field magnet poles, or a wire working
out of its connection may cause a short circuit and blow the fuse, etc.
It will be readily seen that these small troubles, if not attended to in
time, are the causes of others far more serious, yet a turn of the wrench
or the screwdriver in proper time may easily prevent such troubles on
the road.
Trolley Car Operation. — ^To start the car, see that the
brakes axe ofiE, the canopy switches closed; then move the
controller handle to the fkst notch. After the car is well started,
move to the second notch, and after a short time to the third,
and so on to the last. Don't stop the handle between notches,
and don't move it too slowly. On the other hand, do not move
too rapidly from the fir<?t notch to the second.
Always wait for the car to get up to the speed corresponding to the
notch the controller handle is on before going to the nejct notch, other-
wise more current will be used than is necessary.
In shutting ofiE the current the handle may be moved around
as rapidly as desired to ''off" from whatever position it may
happen to be on. When stopping at any point, the reverse
lever is sometimes used to make the car go backwards. Never
reverse while the car is running, unless to avoid an accident.
But if it be absolutely necessary to stop the car quickly, pull
the brake on with the right hand and shut off the current with
the left at the same time; then with the right hand free, throw
the reverse lever and turn on a very little ciurent.
If too much current be turned on, the wheels will lose their adhesion
to the rails and spin backwards, which will increase the minimum dis-
tance in which the car may be possibly stopped.
Sometimes a very violent stop must be made, when the brakes fail,
possibly; or the trolley comes off, in which case reverse and put the
2,650
HAWKINS ELECTRICITY
controller handle on the highest point of the controller. This causes
an interaction between the motors which brings them to a standstill
It may dama^^ the apparatus, however, and should only be used in
rare emergenaes; this method is only available when there are two
motors on the car.
When approaching curves or ttimouts the power should be
turned off, appl3ang such power upon reaching the curves as
may be necessary to carry the car easily arotind.
The conductor should be on the rear platform with the trolley rope
in his hand, ready to give the signal in case the trolley jumps the wire,
fto. 3,744. — ^Three spectacle automatic double route home and distant semaphore signal
llie post B consists of two lengths of channel iron strengthened by a lattice structural
the base being bolted to, or incorporated with a foundation of concrete, A. The top con-
sists of a plauorm G, railing E, semaphores P. being pivoted to short posts and operated
by motors and accessories housed m watertight base boxes C D. Tliis arrangement
protects two tracks having trains running in tiae same direction.
in which case the motorman should move the controller handle to "oflE"
until he is notified to go ahead. The motorman should never stop on
curves unless absolutely necessary.
In nmning down grades, always have the trolley on the wire,
the controller handle at **off," and the brake arranged so that
it can be appUed instantly. Digitized by Google
ELECTRIC RAILWAYS 2,651
Before going down a steep grade slow up the car, and set
the brakes gradually. If the wheels slide, loosen the brakes to
allow them to get hold of the track; then apply the brakes
again. If the brakes then fail, reverse the motors. If, in the
meantime, the trolley leave the wire, so that there be no
power, reverse arid throw the controller handle to the last notch,
which will make the car come to a standstill.
In running up heavy grades, get the car up to speed, if possible,
before reaching the grade so that it will not require so much
current to climb up.
If the car be started while on a heavy grade, it will require a
very large amotint of current. Whether to climb these grades
in series or parallel positions is a question on which instructions
are given in each individual case. If the wheels slip on the rails,
the sand box can often be used to advantage; but always be
sure, especially in wet weather, that the sand is dry. Do not
use the sand too freely, as you may run short just when it is
needed most.
If the power give out, notice if the other cars experience the
same trouble, as it may be due to an open circuit on the line;
if so, throw the controller handle to ''off,*' close the lamp circuit
and wait until the lamps light up.
If, when the lamps light up, the equipment will not move
the controller handle on the first point, the motorman should
first look to see whether his fuse has blown or burned out; if so,
open the head switch, or tie down the trolley pole and replace
the fuse.
If the fuse be not blown, the rails may be dirty and the car
insulated from the rails.
In this case have the conductor jam the switch bar between the
wheel and rail, while the motorman starts the car.
In rare instances there is a case of dead rail, gitzedbydooglc
2,652 HAWKINS ELECTRICITY
A length of wire should be kept in the car where possible, and one
end pla^d on the rail back of the car toward the power station, and
one on any exposed part of the iron truck. Always place the end on
the rail first, otherwise a shock will be received.
In case, as the car goes along, a peculiar jtmiping action
occur, known as the bucking of motors, the motor affected should
be cut out by means of the motor switches in the controller.
Instructions are given the motorman how the motors are cut out on
each different type of controller. For remedies for more troublesome
accidents see below.
After bringing the car into the car house have the controller
at "off,** take off the controller handles, pull down the trolley
and tie it a few inches below the trolley wire.
Points Relating to Controller Operation. — The question
of the proper handling of the controller is one in which grades,
the weight of equipment, motors and controller, all enter. It
is the usual practice to instruct motomaen to handle their
controller so as to get the equipment up to full speed in a certain
time; but they should be fully instructed to realize the difference
between the time when they are operating near the power sta-
tion, or at the end of the line, where the voltage drop is greater.
In this case the acceleration is slower, and to turn the controller
on too fast will increase the drop on the line and decrease the
acceleration of the motor.
In climbing grades the question arises whether the motors should be
in parallel or in series. This depends largely on the location of the
car with respect to the vohage delivery to the trolley at this point
If the voltage drop be considerable with the motors in parallel, the
series position will be found more economical, and the available energy
for the equipment greater. It has been proven beyond a doubt that
the proper handling of the controller will save as much as 20 per cent
in the coal bill. The curves (Fig. 3,745) show some data obtained
from the Chicago Street Railway, illustrating the diflference in power
consumption between a rapid start and a slow start
ELECTRIC RAILWAYS
2,663
Failure to Start Car. — If the car fail to start when the
controller is "on" and both overhead switches are closed, the
trouble is due to an open circuit, and probably to one of the
following causes :
1. The fuse may have blown or melted. Open an overhead switch
or pull off the trolley and put in a new fuse, removing the burned ends
from under the binding posts before doing so. Never put in a heavier
fuse than that specified by the company, as it might result in damage
»50
\ 1
717 H^ flAXlrtUM
Ti — \ — r
Tl rtt niLLWWf R IS TyRNEO OH
-.EtABTfW,V£Li!sATTUll.FUlLLrtlf£R fj 5 p^tT
9i - - -
sso
6 7
SECONDS
PJ€. 3.745. — Curves showing advantage of using controller correctly.
to the equipment by allowing too large a current to flow. The fuse
may blow because of some trouble on the car, as will be explained a
little further on.
2. On a dry simimer day, when there is much fine dust on the track,
it happens that the car wheels do not make proper contact with the
rail and the car fails to start. In such a case try to estabUsh contact
by roddng the car body. Should this fail to work, the conductor should
take the switch bar or a piece of wire and, holding one end firmly on a
dean place on the rail, hold the other against the wheel or truck. This
wiU make temporary connection until the car has started. The con-
ductor should be sure to make his rail contact first and keep it firm
duiing this operation or he may receive a shock. o
2,654
HAWKINS ELECTRICITY
'S
5
ELECTRIC RAILWAYS 2,655
3. If the track conditions be apparently good, it may be that the
car stands on a piece of dead rail, a piece of rail on which the bonding
has been destroyed. In that case the car conductor would have to
go to the next rail section with a piece of wire to connect the two rails
and then order the motorman to start his car.
4. A brush or two may not have been placed, or, if placed, may fit
too tightly in the brush holder, so that the springs do not establish
contact between the brush and the commutator. If this be the case,
remove the brushes and sandpaper them until they go into the brush
holder easily.
5. The contact fingers on a controller are rough, burnt, and perhaps
bent so that the drmn cannot make contact. It may also be due to
wear on both the contact surfaces of the drum and the finger, which
may have been biirnt and worn away to sufch an extent that contact
is not established when the controller handle is placed in the first notch.
Try to smooth the burnt surface with sandpaper and bend the fingers or
contacts into their proper position. Shomd this fail, then operate the
car with the other controUer. In this case the conductor should be
on the front platform to handle the brake and give orders to the motor-
man when to start and stop, as the occasion requires. Under these
conditions the car should never be allowed to travel at a high speed.
6. A loose or broken cable connection. This can be located and
placed and fastened in its position. It is, in most instances, a cable
connected to one of the motors, rheostat or lightning arrester, and very
seldom in the controller stand.
7. A burnt rheostat. A rheostat may have received too great a
current for some time and the first contact terminal may be broken.
In such a case, if temporary connection cannot conveniently be estab-
lished, the car will not start at the first notch, but at the second it will
start with a jerk.
8. If the car refuse to start on the first contact, but start all right
on the second and acts normal thereafter, then there is an open circuit
in the rheostat, either internally, or the first cable connection is broken.
Abnormal Starting. — Sometimes a car will start with a
jerk, but afterwards run smooth and normal. This indicates
a short circuit in the rheostat. Examine the rheostat terminals,
as the trouble may be due to the crossing of the cables or a loose
cable touching another terminal of the rheostat; ^^^^t touch
it but run car back to bam.
id8c§*
2,656 HAWKINS ELECTRICITY
Ques. What causes a motor to increase speed beyond
normal?
Ans. This may be due to a short circuited or burned out
field magnet coil.
The motor should be cut out.
Ques. What causes a car to start with a jerk and the
gears to make considerable noise?
Ans. This may be due to worn pinion teeth, or worn bearing
permitting loose meshing of teeth, or the key seat on the arma-
tnire shaft may have become wider by the constant wear of a
loose key.
Ques. What should be done if the motors start with a
jerk or do not run smoothly?
Ans. The conductor should lift one of the trap doors at a
time, while the car is running to examine the commutator and
brushes of each motor.
Should there be seen a flash all around the commutator or connecting
two brushes, there is an open circuit in the armature. Cut out the motor.
Faulty operation. — Heavy flashing and smoking in the
controller is due to dirt, moisture, metal dust in the controller,
or the too slow turning off of the controller. Open the over-
head switch and blow out the dust from the ring terminals^
also remove all dust at the lower ends of the controller and see
that it is dry.
Should the lamps not light upon turning the lamp switch examine
lamp circuit fuse.
If fuse be not blown, either a lamp is not screwed up or one is
burned out. In either case none will bum because they are connected
in series. - o
ELECTRIC RAILWAYS
2,657
ftes. 3,761 and 3,752. — Westinghouse interpole motor as used on Piedmont railway. Fif .
8,751 pinion end of motor; fig. 3,752 commutator end. The motor is rated at 110 horse
power at 750 volts. Two motors are connected in series for 1,500 volt operation. Theao
moton are geared to 36 inch wheels with a 20 tooth pinion and 57 tooth gear. The can.
weighing complete without load, approximately 41 tons, are operated at a schedule sj^eem.
o£ 34 miles per hour. The weight of the motor complete is 4,150 potmds. The armature
is e^^dally designed to withstand the higher voltage, being insulated with mica, and
having liberal creepage distances provided at the end of the commutator. The brush
holders have extra heavy porcelain insulators. The length of the dust ring at the end
of the commutator, and the clearances from the line parts of the motor to the ground are
greater than in ordinary designs.
2,658 HAWKINS ELECTRICITY
Motor Troubles. — ^A few motor troubles often met with are
given here: for a full treatment of the subject in general, see
Guide No. 3.
A sharp rattling noise when the car is traveling at high speed is the
consequence of an imeven commutator.
A commutator that is flat in places, or a few bars that have become
loose and project slightly, cause the brushes to be quickly forced away
from the commutator by the high bars, and to be forced back onte
the lower ones by the brush holder spring as soon as a high bar has
gassed. This causes heavy sparking at the brushes and excessive
eating of the commutator segments, besides the rapid wearing down
of the brushes. The rapid succession of these changes causes the
noise, and this can be remedied only in the repair shop. It should be
reported.
A dull thumping noise, also connected with sparking at the brushes,
may be due to the armature striking or rubbing against the pole pieces.
If this be due to loose bearing^ the cap bolts should be tightened, but
if, on account of worn out boxes, the car should be taken to the barn at
a reduced speed.
Abnormal heating of one of the motor armatures may be due to its
striking the field poles when rotating.
Heating of the motor may also be due to a defective brake, caused
by weak release springs or too short a brake chain.
Again, heating may be due to the oil or grease used which does not
melt properly, if at aU.
A full grease or oil cup is no sign of proper lubrication.
If it be found that bearings heat, in spite of full grease cups, take a
clean stick, make a hole through the grease down to the shaft, pour in
soft oil and go ahead.
It may be well occasionally to feel the car axle bearings, which get
pretty warm when insufficiently supplied with oiL
Before Starting a Train. — ^When the train is turned over
to the motorman he should:
1. Pass along the outside and carefully examine the bus
line and cable jumpers between cars, to assure himself that all
connections are properly made and that the main switches
are closed;
2. Pass through the train, closing air compressor and third rail
ELECTRIC RAILWAYS 2,659
switches in each car, and opening master control switches in all
cars except head car or car from which train is to be operated;
3. Pass along outside the train again and satisfy himself that
the air compressors are working properly;
4. Take position in the motorman's compartment at for-
ward end of train and note the brake pipe pressure, and
close master controller switch;
5. Set circuit breakers by moving the circuit breaker switch
over the master controller to the on position, holding it there
about one second to allow time for all circuit breakers to set;
6. Test the air brakes, and if same work satisfactorily, the
train is ready to start.
Starting a Train with Master Control. — ^After receiving
the signal to start, press down the button in the controller
handle, insert the handle key and give it a quarter ttun.
Ques. Why should the button in the controller handle
be held down?
Ans. To prevent the pilot vajve in the controller operating
and applying the brakes. . ^
Ques. What next should be done?
Ans. Move the controller handle to the left as far as it will
go, holding it there against the spring, which tends to return
it to the **ofI" position.
The motor control will then notch up to full speed position by the
automatic progression of the contactors in successive steps, under the
control of the current limit relay. In this position it is not necessary
to hold the button down to prevent application of tiie brakes.
To Start Slowly. — Move controller handle to the left to
first point. In this position both motors on each car are
2,660
HAWKINS ELECTRICITY
connected in series with all resistance in circuit and the motor
control will not notch up to higher speed.
Ques. How is the speed increased slightly?
Ans. By moving the controller handle to th« second point
and quickly returning it to the first point.
Ques. What will happen if the controller handle be
left in second point?
Pig. 3,753. — ^Westinghouse interpole 760 volt railway motor, showing axle caps and axle dust
guard in place. This is another view of the motor tised on the Piedmont locomotives as
&own in figs. 3,751 and 3,752.
Ans. All resistance will be progressively cut out giving full
series or half speed.
Ques. What are the running positions ?
Ans. The second and fotuth notches.
The train should not be operated for more than a few minutes at
a time on the other or intermediate notches. o
ELECTRIC RAILWAYS 2,661
Reversing. — ^When the train has come to a stop it may be
reversed by moving the controller handle to the right to the
first point. This connects the motors in reverse cHrection in
series with all resistance in circuit.
Ques. How fast can the train be run in reverse
direction?
Ans. Up to half speed.
Ques. How can higher speed be obtained in reverse
direction?
Ans. By operating the master controller at the other end of
the train.
This, of course, strictly speaking, is not reverse operation, but for-
ward operation, considering the rear car as the front end of the train.
Train Fails to Start. — If, when all the connections are made
and the controlling handle operated properly, the train do not
start, the fault may be due to various causes, as
1. Failure of power;
2. Fatdt in master control circuit;
3. Fatdt in motor control circuit;
4. Non-release of air brakes. ]
Ques. How may a failure of power be detected?
Ans. By turning on the lights; if lights do not bum, the
current is off.
Ques. Name some faults liable to occur in the master
control circuit.
Ans. Loose cable jumper; grounded train cable; poor con-
tact in master controller; master control fuse blown.
Ques. How is a loose cable jumper detected?
Ans. By noting if the contactors on each car be working
while the train is accelerating. Digitized by Goog
2,662
HAWKINS ELECTRICITY
Digitized tjyVjOOQLc
ELECTRIC RAILWAYS
2,663
The trainmen should make the observations. If there be a loose
cable jumper, aU cars ahead of the jumper will operate.
Ques. How is a grounded cable detected ?
Ans. By operating the master controller; if the master
controller fuse blow, it indicates that one or more wires of the
train cable are grounded.
^^
S..y>,^^
F1
S%P
't-^
■5
^P
;i,
^
«i
fi
o
a
'6
o
2'
o
-i-
a
n
--
o
o
o
^j_
i
\^r
c
o
-
g
1
is
fl
o
*
J
a
a
e
oId
o
D
0^
_9
D
2E
6
6
s
-1
Fig. 3,755. — Schematic diagram of comiections ty];>e HL control for four 75 horse power 500
volt motors.
Ques. How is a ground in the train cable located?
Ans. Disconnect train cable on operating car from rest of
train by removing train cable jumper from its socket on second
car. If the fuse now blow, when the controller handle is operated,
it indicates that the ground is either in the operating car or its
train cable jumper. ^
2,664 HAWKINS ELECTRICITY
To determine which be groxinded, remove jumper, if fuse blow when
the controller handle is operated, the ground is in the cat; if it do not
blow, the ground is in the jumper.
Ques. How is poor contact in the master controller
detected?
Ans. Open master controller switch, remove cover from the
controller and turn the handle slowly, noting if each finger
make good contact with the drive.
Ques. What indicates a blown master controller fuse?
Ans. If, in turning the master controller handle to the first
notch and thus opening the master controller switch, no arcing
occur, the fuse is blown or is imperfect.
Ques. Name some faults liable to occur in the motor
control circuit.
Ans. Main fuse blown; shoe or trolley fuses blown; bus
fuses blown; loose or disconnected bus jtimper; circuit breakers
open.
The blowing of the main fuses should not occur often. It is
caused by short circuit or grounding in the motor circuit. Before
renewing main fuse open the main switch.
The grounding or short circuiting of the wiring on a car or truck may-
cause the trolley fuse to blow. The trolley or trolleys should be
pulled down and trolley switch opened before replacing trolley fuse.
A shoe fuse may blow for short circuit, grounding of the car wiring
on some part of the car or truck, or may be caused by a contact shoe
on the car or train grounding. In replacing fuse, first open the third
rail switch and insert the wooden paddles, provided for that purpose
between all shoes on that car that are in contact with the third rail
A loose or disconnected bus juniper may. be detected when the
train is at a crossover and current cannot be obtained on operating
cars, although other cars of the train have current, thus indicating
blown fuse or fuses, or that a bus line jumper is loose or disconnected
between the operating and adjacent cars.
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ELECTRIC RAILWAYS 2,665
Electric Ship Propulsion. — ^Although the steam turbine is
extensively used for propelling vessels of various kind it is
subject to certain limitations which detract from its value,
especially for heavy marine work such as battleships.
For instance, while the turbine operates at its highest efficiency
when driven at a very high rate of speed, the screw propeller
of- the ship attains its maximum efficiency when ttmiing at a
speed relatively very low — about 160 revolutions per minute.
This means the introduction of gearing or some other mechanism
to reduce the speed of the turbine to that best adapted to the
propeller.
Furthermore since the turbine runs inherently in one direction
only, means must be provided for reversing the propeller, either
by providing a reverse gear, or by installing on the tiurbine
shaft an extra set of vane for backing. The latter method is
the one generally used, although the backing turbine is driven
idle by the ahead tiurbine, thus increasing the cost weight and
space of the unit while decreasing its mechanical efficiency.
Flexibility of control in both backward and forward move-
ments is of the highest importance in the fighting ship and for
this reason the builders have been forced to employ a driving
mechanism embodjring every possible feature of advantage
regardless of the cost of installation and subsequent operation.
Another essential in the propulsion of a battleship is that it
shall be capable of cruising day in and day out at about
three quarter speed and at the same time be able to make a
sudden, though perhaps long continued spurt at its maximimi
speed.
The tiu-bine is essentially a one speed machine and its ideal
operating speed is a high one. In order, therefore, that it be
made capable of attaining the higher speed, it must be operated
for the greater part of the time (while cruising) at compara-
tively low efficiency. ,,^,,3, by Google
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HAWKINS ELECTRICITY
The object of the electric drive is to overcome the inherent
defects or limitations of the turbine, that is to say, its function
is similar to the so called * 'transmission" of an automobile in
that it gives flexibility of control and permits the turbine to
run at its most economical speed.
Various combinations of machinery for electric propulsion
have been worked out, being suggested by plans and principles
of proved appropriateness which have been employed in electric
power plants on land. These various systems have been pro-
posed by Emmet, Mavor, Durtnall, Hobart, Day, and others.
The problem has been to so combine generating units with
Pto. 8,766 — ^Elementary diagram illtistrating the essentials of electric ship propulsion. Two
turbine alternator units are shown on the right which are wired for various connections
with the motors; the latter ox>erate the jnopellers A, B, C, and D.
motors that the maximum efficiency of the turbine could be
obtained under all working conditions of the vessel, as in
maneuvering, cruising at low or moderate speed, and when
being driven at high speed.
An examination of the simple diagram, fig. 3,756, will serve
to make dear the plan of the driving mechanism. The generating
plant is composed of two independent tiu-bine alternators,
each of which is capable of delivering one-half of the total
power necessary to run the ship at maximtim speed. The
driving motors are of the three phase variety and each motor
ELECTRIC RAILWAYS
2,667
IS equipped with two sets of pole piece — one of twenty-four
poles and the other of thirty-six. By operating the motors on
one or the other set of pole, the speed is changed without
impairing the efficiency in any way. The plan of operation
is to drive the motors at the lower speed for cruising with only
one turbine alternator in operation, while for the greater speed
the two alternators would be operated in tandem with the
motors arranged to run at their maximum speed. Thus it will
be seen that when cruising, the one alternator is running at its
full efficiency as are also the motors, while the second alternator
Fig. 3,757.— Hobart's alter-cycle control of induction motors for electric ship propulsion.
There are four motors £. P, G and H, wotmd respectively for 24, 36, 48, and 72 poles.
The maximnm speed of the propeller shaft is 100 r.p.m. with full power of all the motors.
To run the motors at 100 r.p.m. requires frequencies of 20 cycles for the 24 pole motor,
30, for the 86 pole motor, 40, for the 48 pole motor, and 60 for the 72 pole motor. Thus
to obttun equal r.p.m. the frequencies of the four alternators A, B, C, L) are respectively
made 20, 30, 40, and 60. To obtain these frequencies when the alternators are down say to
600 r.p.m. requires respectively 4, 6, 8, and 12 poles for the alternators A, B, C, and D.
To drive the ship at two thirds speed, motors T and H are connected to alternators A
and C, which provide respectively % of the frequencies of B and D, to which P and H
were connected for full speed running. Since for the lower speed only about 9b as much
power is required as for top speed, alternators B and D, and motor E and G are shut
down. Por half speed a single motor is sufficient; this can be provided byoperatiuE
motor H from alternator B. or G from A. One third speed is obtained by operating H
from A.
is idle. Likewise, when full speed is required, the second alter-
nator is started and run also at its peak of efficiency.
The following description of the machinery for electric pro*
pulsion in the new battleship California will illustrate more
in detail the features of electric propulsion: ^^
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HAWKINS ELECTRICITY
The outfit consists essentially of a port and a starboard unit, each
consisting of a turbine driven, two pole, qtmrter phase alternator and
two double squirrel cage induction motors. Direct current field ex-
citation, at 230 vohs, for the alternator, is supplied from a turbine
driven alternator in the engine room, or, if desired, is obtained ixom
the ship's mains.
Conversely, the two exciters may be used in port to supply power
to the ship's mains, and thus form two valuable additions to the vessel's
power plant.
The motors have two possible arrangements of pole, the change
from 36 poles to 24 poles being accomplished by simply throwing a
switch. There is one motor in a separate compartment for eadh of
the four shafts.
For 21 knots both turbine tmits are run and the four motors are used
in their 24 pole rig (low gear). This reduces the full turbine 8x>eed of
2,000 r. p. m. to 165 r. p. m. of motor or propeller.
iiimM"""">"'mi
ViB. 8,758. — ^The Menlees system of propelling ships by gas engines. In the figure A is a
six cylinder gas engine coupled to a dynamo B. The shaft C of the d^rnamo and engine
is adapted to be connected by a clutch D with the shi^t £ of the electric motor P, which
is connected with the propeller shaft. In operation, at all ahead ship speeds direct driv-
ing mav be employed, but, for speeds less than half, the electrical transmission may be
used, the motor P, receiving electrical energv from the djrnamo B. The drive may also
be employed for reversing the astern speed by not greater than half the full ahead
speed, suitable switches and gear being provided.
At cruising speeds one turbine is connected to the four motors in
their 36 pole rig (high gear). Thus either turbine at 2,000 r. p. m.
drives four motors at 110 r. p. m. The other turbine is meanwhile
not in use.
When the motors are not connected, the turbine runs at no load and
the motors stand idle. If connected to one alternator, all the motors
turn (if in the same xK>le setting) at the same speed, although, if it be
desired to back the port and at the same time stop or go ahead on the
starboard motors, this is possible. In other words, when in cruising
rig the ship can be quickly started^ stopped, or turned by various
combinations of the four motors driven by one turbine, and power
for 19 knots is available. ^
ELECTRIC RAILWAYS
2,669
Speed control with eithef one or two alternators running is entirely
by turbine throttle or on the so called "variable-frequency" principle.
It is at once evident that the electricity between turbine shaft and
propeller shaft simply perfonns the same ftmction that a clutch and
gear box do on an automobile. The electric machinery simply makes it
possible to reverse the propeller shafts and keep the turbine running
in the same direction, and also gives two gear ratios between turbine
shaft and propeller shafts.
The electric rig does not nave a "direct drive," as does an auto-
mobile, because this is just what is not wanted in a ship. On the other
hand, the electric rig gives two speed ratios ahead and two backing,
while the automobile gives usually two ahead (besides "direct") and
Pig. 3,759. — Generating unit of U. S. Collier Jupiter, consisting of an alternator directly
connected to a turbme.
one backing. Being in any gear setting with either ship or automobile^
to go faster f speed up the engine; to slow, slow the engine. Without "shift-
ing gear" speed changes can be made in no other way. In the automobile
the clutch can at any time be thrown out and leave the engine rtmning;
with the ship, the motors may be disconnected electrically and leave the
turbine runnii^. ^
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HAWKINS ELECTRICITY
Between the exciter and the alternator there are, besides the usuak
protective circuit breakers, one switch and one rheostat. As has been
said, the ship's circuit can be used for supplying excitation for the
alternators, or in port the exciters, which are of about 300 kw. capacity,
can be used for supplying power to the ship's mains.
The four main leads from the armature of, say, the port alternator
go through a four pole switch to the port bus bars. As this switch
IS opened only when no power is on the system, it is of the usual knife
type. The two port motors are connected in parallel and tiien through
either one of two electrically actuated main oil switdies to the bus bars.
Fig. 3,760. — View of 6,000 horse power Melville- MacAlpine speed reduction gear with case
broken away showing construction. It is a double helical spur gear, designed with in-
volute teeth, and a transmission capacity of 6,000 horse power at a pinion speed of 1,500
r.p.m. The pinions have 35 teeth, the spur wheels 176 teeth. The 176th tooth con-
stitutes a bunting cog and equalizes the wear. The pitch circle diameters are 14 ins.
and 70 ins. respectively. The reduction ratio is thus practically 5 to 1, hence the power
is delivered from the gear at a speed of only 300 r.p.m. The pitch line speed is 6.600
ft. per minute and the design is based on a hmiting pressure of 450 lbs. per inch of tooth
contact. Provision is made for the liberal use of lubricating and machine oil. Rear-
Admiral Melville writing in Proc. Inst. Civil Engineer, Feb., 1910, states as follows: A
full power test of 6,500 horse power was carried out for a period of 40 hours from 2.30 P.M.
on Oct. 16, 1909, till 6.30 A.M. Oct. 18. At the close of this test the gear was fotmd to
be in excellent condition and without any sign of wear. This established without ques-
tion the fact that gearing could be made to transmit such large powers continuous at
high speed.
When closed, one of these oil switches. connects the pair of motor for
"ahead" operation; and when closed, the other switch connects the
motors for *' astern" operation. Only one of these switches can be
ELECTRIC RAILWAYS
2,671
closed at a time, and the closed switch is locked so that it cannot be
opened until after the alternator field switch is open. This last pro-
yiaon makes it impossible to break the main circuit until the current
in it practically ceases to flow.
In each motor circuit there is a four pole, double throw switch. One
closed position of this switch coimects the motor for 36 poles, the other
closed position for 24 poles. As the pole changing switches are never
used with power on the circuit, they are simply knife switches.
When in cruising rig with all four motors driven by one turbine
unit, the port and starboard bus bars are connected together. At all
Fig. 0,000. — ^Arrangement of Westinghouse marine steam turbines with Melville-MacAlpine
reduction gear, proposed for U. S. S. Baltimore. The entire equii>ment is shown
as if installed in one of the two engine rooms occupied hy the reciprocating engines with
which this vessel was actually fitted. Since the gearing is of 98 H per cent or conserva-
tiveljr 98 % efficiency, the output for a group of turbine such as would drive the Mau-
retania at a speed of 25 knots would be 60,500 4- .98 =62,000 horse power, requiring an
estimated weight of 260 tons. The weight of gearing for a ship of the Mauretania's dis-
placement and speed would amount to some 300 tons in place of a weight of some 1,100
tons of machinery which would be saved. The turbines of the Mauretania are rated at
70,000 shaft horse power. Even the comparatively low speed at which these turbines run
is too high for maximum propeller efficiency. It is hardly possible that the propeller
efficiency exceeds 55 per cent, which means that the actual effective propelling power is
only about 38,500 horse power. At a lower speed well within the capabilities of the
reduction gear, a propeller could be made that would have an efficiency of not less than 66
per cent. With this improved efficiency, the shaft horse power required for the same
effective propelling power would be somewhat less than 67,000, a saving of almost 15
per cent. With the turbine and propeller direct connected so that both revolve at the
same speed, not only is it necessary to sacrifice the efficiency of the propeller, but also
the efficiency of the turbines.
other times the port and starboard sides of the ship are not electrically
connected.
As the alternator field switch, the main switcl^, and even the turbine
governors will in all probability be electrically operated, two master
2,672 HAWKINS ELECTRICITY
contoljers, one in front of the instrument board in each engine room,
will sufl&ce for handling the entire main propelling plant.
The author believes the time and money spent in devising
such complication of machinery to secure flexibility of control
and to obtain the necessary speed reduction between high speed
turbines and low speed propellers could have been employed
more profitably in perfecting a two speed and reverse gear, or
more especially in seeking* a commercially successful method of
generating steam at considerably higher pressures and degrees
of superheat than are conmion at present, for use in triple
or quadruple expansion engines.
In view of the economic results obtained in the White system
and in the various "locomobiles,** a quadruple expansion con-
densing engine, not handicapped with the present boiler limita-
tions, and operating under favorable conditions, that is to say,
under desirable initial and terminal pressures, and with a
sufiBcient degree of superheating and reheating to secure passage
of the steam through the cylinders without condensation,
should produce an indicated horse power on five poimds of water
per hour, or about one third the amount now required.
In devising any new method of steam making, a study of Prof.
Carpenter's tests on the White steam generator will show the
marked effect of rapid circulation in reducing the heating
surface necessary for a given output.
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MOTION PICTURES 2,673
CHAPTER LXXIV
MOTION PICTURES
The subject of motion picttires may be included with pro-
priety in a work on electricity because of the electric arc gen-
erally used for illumination and the auxiliary apparatus neces-
sary for the proper working of the arc; in some installations the
generating machinery being included, comprising an isolated
plant.
While arc lighting has been treated at considerable length in
the chapter on electric lighting, the special adaptation of the
arc for moving picture machines is best explained in a separate
chapter. For completeness, the subject of motion pictures is
treated at length with respect both to its electrical and non-
electrical features. With this in view, a comprehensive expla-
nation of motion pictures is naturally given in the order of the
outline below which is followed in part.
1. Cities; 9. Projection;
2. The film; 10. Reproducing the pictures on the screen;
3. Motion picture cameras; 11. Stage efifects;
4. Taking the pictures; 12. Motion picture theatres;
6. Developing; 13. Theatre lighting;
6. The electnc arc; 14. Installation;
7. Auxiliary apparatus; 15. Operation;
8. Motion picture machine; 16. Care and repair.
Optics. — By definition, that part of physics which deals with
the property of light is known (w optica. ^
2,674
HAWKINS ELECTRICITY
Ques. What is light?
Ans. Various hypotheses have been made, the most important
of which are the emission or corpuscular theory, and the undu-
iatory or wave theory.
The emission theory assumes that luminous bodies emit, in all
directions, an imponderable substance which consists of molecules
of an extreme degree of tenuity. These are propagated in right lines
"with an almost infinite velocity. Penetrating into the eye, they act
on the retina and produce a sensation which is called vision.
The undulatory theory assumes that all bodies, as well as the
celestial spaces are filled with an extremely subtle elastic medium.
Fig. 3 J62. — Images i>roduced by small apertures showing the crossing of luminous rays at
the aperture causing inversion of the miage.
called the luminiferous ether, the luminosity of a body being due to
an infinitely rapid vibratory motion of its molecules, whidi, when
communicated to the ether, is propagated in all directions in the form
of spherical waves, and this vibratory motion, being thus transmitted
to the retina, produces the sensation called vision.
Ques. What is an image?
Ans. An image is the appearance of an object at a place
where no object exists.
Ques. What is the difference between a real and a
virtual image?
Ans. A real image is formed when the rays actually meet;
a virtual image is formed when the rays only appear to meet.
MOTION PICTURES
2,675
Ques. What is a mirror?
Ans. A polished surface which reflects objects placed before it.
According to their shape, mirrors are called plane, concave, convex,
spherical, parabolic, conical, etc
Ques. What kind of image is seen in a plane mirror?
Ans. A virtual image.
Figs. 3.763 and 3,764. — Formation of imaaea bjr plane mirrors. The determination of the
portion and size of image resolves itself into investigating the images of a series of point.
CASE I. Single point A placed in front of a plane mirror, as in fig. 3,763. Any ray AB,
incident from this point on the mirror is reflected in the direction BO, making the angle
of reflection DBO equal to the angle of incidence DBA. If a perpendicular AN, be let
f^ from the point A over the mirror, and if the ray OB, be prolonged below the mirror until
it meets this perpendicuUu* in the jwint A', two triangles are formed, ABN and BNA',
which are equal, for they have the side BN common to both, and the ang^les ANB, ABN,
equal to the angles A'NB, A'BN; for the angles ANB and A'NB are right angles, and
the angles ABN and A'BN are each equal to the angle OBM. From the equality of these
triangles, it follows that A'N is equal to AN; that is, that any ray AB, takes such a
direction after being reflected, that its prolongation below the mirror cuts the perpendicular
AA' in the point A , which is at the same distance from the mirror as the point A. This
applies also to the case of any other ray from the point A, as AC. It follows, that all
rays from the point A, reflected from the mirror, follow after reflection, the same direction
as if they had all proceeded from the point A'. The eye is deceived, and sees the point
A at A', as if it were really situated at A'. Hence,*in plane mirrors, the image of any point
is formed behind the mirror at a distance equal to that of the given point, and on the perpen-
dicular let fall from this point on the mirror. CASE ll: Object AB placed in front of the
mirror, as in fig. 3,764. The image of anv object will be obtained by constructing the
linage of each of its points, or at least, of those which are sufficient to determine its form.
Fig. 3,764 shows how the image A'B' of any object AB is formed.
Ques. How are images produced by small apertures?
Ans. When luminous rays, which pass through a small aper-
ture into a dark chamber, are received upon a screen, thev form
2,676
HAWKINS ELECTRICITY
'^'^ '^ B ^
aw ^ 5 ^ a
e*3 r
■B
Sk *< k- (U- 3
^ gill I
1.11 "-
I, S ai! .^.tJ
11*1''
slllll
images of external ob-
jects as shown in fig.
3,762.
Ques. Why are
these images hi-
verted?
Ans. Because the
luminous rays proceed-
ing from external ob»
jects, and penetratijpg
into the chamber, croU
one another in passi<H
the aperture as shotlpi
in fig. 3,762.
Ques. Whatisiijih
flection? '••
Ans. The changeil
direction experienced
by a ray of light, or if
other radiant energgf,
when it strikes a sur-
face and is thrown back
or reflected, as shown
in fig. 3,767.
Laws of Reflec-
tion. — ^When a ray of
light meets a polished
surface, it is reflected
according to the two
following laws:
MOTION PICTURES
2,677
1. The angle of reflection is equal to the angle of incidence,
2. The incident and the reflected rays are both in the same plane,
which is perpendicular to the reflecting surface,
Ques. Describe a spherical mirror.
Ans. If a segment were cut £:oin a hollow sphere and the
surfaces were silvered or polished, each side of the segment
would be a spherical mirror.
anffl
reflecting surface,
equal to the
^ angle ION,
perpendicular to the
The inner side is a concave spherical mirror, and the outer side, a
convex spherical mirror.
Ques. What is the focus of a curved mirror?
Ans. A point where the reflected rays meet or tend to meet
if produced either backward or forward.
There is a real or principal focus, a virtual focus, and conjugate
foci. The principal and the conjugate foci are always on the same
2,678
HAWKINS ELECTRICITY
"t^
(^^-rrrTH.V.Vj
\ A
A
^^ ^ \/
w
\
*\
\
Fig. 3,768. — Mtdti-image formed by two mirrors. When an object is placed between two
plane mirrors, which form an angle with each other, either ri^ht or acute, images of the
object are formed, the number of which increases with the mclination of the mirrors.
If they be at nght angles to each other, three images are seen, arranged as represented
in the figure. Tlie rays OC and OD from the point O, after a single reflection, give the
one, an iniage O*, and the other an image O'*, while the ray OA, which has undergone
two reflections at A and B, gives the third image O'''. When the an^le of the mirror is
60", five images are produceof, and seven if it be 45**. The number of image continues to
increase in proportion as the angle diminishes, and when it is zero (mirrors parallel), the
number of image is infinite. In general, if two mirrors be inclined to each other, the
number of image they produce is equal to the number of tunes the angle 'between them
18 contained in o60.
Fig. 3.769. — ^Position of image in a plain mirror. Let a candle be placed exactly as far in front
of a pane of window glass as a bottle full of water is behina it, both objects being on a
perpendicular drawn through the glass. The candle will appear to be burning inside the
water. This experiment explains a large number of familiar optical illusions, such as "the
figure suspended in mid-air,' "bust ot person without trunk," "stage ghost," etc. In the last
case the iUusion is produced by causing the audience to look at the actors obliquely thix>agfa
a sheet of very clear plate glass, the edges of which are concealed by draperies. Images of
strongly illuminated Bgures at one side appear to the audience to be in the midst of the acton.
MOTION PICTURES
2,679
side of the mirror as the luminous point, while the virtual focus is always
on the other side of the mirror. The distinction between these various
foci is illustrated in the accompanying cuts.
Ques. What is a parabolic mirror?
Ans. A concave mirror whose surface is generated by the revo-
lution of the arc of a parabola AC about its axis AB as in fig. 3,770.
Ques. What is avoided by the use of parabolic mirrors?
Ans. Spherical aberration.
K E L
A
H
^\
G
F
>.
\
B
\c
Pig. 3.770. — The parabola. A parabola DAC is a curve such that every point in the curve is
equally distant from the directrix KL and the focus P. The focus lies in the axis AB, drawn
from the vertex or head of the curve A, so as to divide the figure into two equal parts.
The vertex A, is equidistant from the directrix and the focus or AB = AF. Any line parallel
to the axis is a diameter. A straight line, as HG or DC, drawn across the figure at right angles
to the axis is a double ordinate, and either half of it is an ordinate. 'Hie ordinate to the
axis H P G drawn through the focus, is called the parameter of the axis. A segment of
the axis, reckoned from the vertex, is an abscissa of the axis, and it is an abscissa of the
ordinate drawn from the base of the abscissa. Thus A B is an abscissa of the ordinate
B C. Abscissse of a parabola are as the square of their ordinates.
Ques. What is refraction?
Ans. The change of direction which a ray of light under-
goes upon entering obliquely a medium of different density
from that through which it has been passing, as in fig. 3,773.
If the incident ray be perpendicular to the surface separating the two
media, it is not bent, but continues its course in a right line.
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HAWKINS ELECTRICITY
According as the refracted ray approaches or deviates from the
normal, the second medium is said to be more or less refringent, ot
refracting than the first.
Mathematical analysis shows that the direction of refraction depends
on the relative velocity of light in the two media.
Ques. Define the index of refraction, or refractive index.^
Pigs. 3,771 acd 3^2. — Concave spherical minarr dfifinitinnju In the diagram Vis the vertex;
MM', the aperture; CV, the principal axis: CS, a secondary axis; C, center of curvature;
F, principal focus (midway between V and C) . Any line drawn from C to the mirror will be
perpendicular to the mirror at that point. This line then will always be the normal whidi
will be used in ma)cin^ the angle of incidence equal to the angle of reflection. Now in fig.
3,772, if AB be an incident ray of light, the angle ABC is the angle of incidence. To find
the direction of the reflected ray draw BR so that the angle CBR equals angle ABC* than
will BR be the direction of the reflected ray.
Pig* 3,773.— Diagram illustrating refraction definitions. All the light which falls on a refractias
surface does not completely pass into it; one part is reflected and scattered, while the other
penetrates into the medium. According to the undulatory theory, the more highly
refracting media is that in which the velocity of propagation is least. In unciystallized
media, such as air, liquids, ordinary gla<^, the luminous ray is sinf^ly refracted; but in
certain crystallized bodies, such as Iceland spar, selenite, etc., the incident ray gives rise to
two refracted rays. The latter phenomenon is called double refrar.tinn. ^
MOTION PICTURES
2,681
Ans. It is the ratio between the series of the incident and
refracted angles.
It varies with the media, for instance from air to glass it is f ; from
air to water, }.
Indices of a few common substances are as follows: alcohol 1.36;
crown glass 1.53; turpentine 1.47; diamond 1.67; flint glass 2.47.
n& 8,?74. — ^Emeriment illtistrating multi-image in ordinary mirror. Let the flame of a candle
be observed very obliquely in an ordinary mirror. From four to ten images of the flame
may be seen arranjged in a row. as here shown. The second image of the series will be by
far the most brilliant.
Laws of Refraction. — When a luminous ray is refracted in
passing from one medium into another of .different refractive
power the following laws obtain :
1. Ldght is refracted whenever it passes obliqtcely from one
medium to another of different optical density;
2. The index of refraction for a given substance is a constant
quantity whatever be the angle of incidence; byGoog
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HAWKINS ELECTRICITY
3. The refracted ray lies in the plane oj the incident ray and
the normal;
4. Light rays are bent toward the normal when they enter a
more refractive mediumy and from the normal when they enter a
less refractive medium.
Ques. Define the critical angle.
Ans. In fig. 3,775, let CD be a surface separating two trans-
parent media, the lower one being the denser of the two (as air
CRITICAL ANGLL
Pig. — ^3,775. — Diagram illustrating the critical angle or t}Mt angle between the incideni ray and
the perpendiaUar drawn to the surface in the^ medium of smaller velocity at the point at which
total reflection begins to occur; the diagram is explained in the accompanying text,
and water). If a ray EO strike the surface it will be bent away
from the normal AOB, along the line OF, in accordance with
the law of refraction sinAOF=)Lt sinEOB. If now the angle
EOB be increased, AOF will go on increasing until sin AOF = 1,
and the refracted ray passes along OD; in this case the ray in
the dense medium makes an angle BOG with the normal such
NOTE. — Effett produced by refraction. Bodies immersed in a medium more highly
refracting than air appear nearer the surface of this medium, but they appear to be more
distant if immersed in a less refracting medium. A stick plunged obliquely into water appears
bent, the immersed part appearing raised. Owing to refraction stars are visible even when
they are below the horizon.
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that /i sin BOG = 1, from which, sin B0G==1-^|a. This angle
BOG is the critical angle.
The critical angle varies with the nature of the substance: thus, for
water and air, it is about 48.5**; for crown glass, 42.5°: for flint elass.
38.6**; for diamond, 23.7.
Ques. What is total reflection?
Ans. When the angle of incidence is greater than the critical
FiGb 3,776. — Construction of refracted ray. Let AO be a ray of light passing through air and
entering water at O. The index is |. Draw two circles with centers at O and with radii
whose lengths are as 4 : 3. Draw AI and BR perpendicular to the normal NN'. Since AO :
BO »» 4 : 3, then AI : BR -4:3. Hence if Al be the sine of the angle of incidence, BR
is the sine of the angle of refraction. If then. BB' be drawn parallel to the normal, and a
straight ruler be placed on the points B' and O, the line OB'', the refracted ray may be
diawn.
angle, none of the light will emerge into the adjacent medium,
but all will be reflected; this is called total reflection.
Total reflection can take place only when light traveling in any
medium meets another medium in which the speed is greater.
Ques. How do external objects appear to an eye under
water? o
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Ans. They appear to lie within a cone whose angle is 97^, as
explained in fig. 3,777.
Lenses. — ^A lens may be defined as, a piece of glass or other
transparent substance with one or both sides curved. Both sides
may be curved, or one curved and the other flat.
The object of a lens is to change the direction of rays of lights
and thus magnify objects^ or otherwise modify vision.
CONE. OF VISION
3!rfJfj;SP^fe;Q?«!;$VS3?Sfi^^
Fig. 3,777.— Appearance of extCTnal objects to an eye under water. Since the critical anfi^
for water & 48 J4% an eye located at M will see objects above the water as thougfh located
within a cone ^ose angle is 2X 48>4'* = 97*. The reason for this is because if the eye
look toward the surface at an angle greater than 48H* it can see nothing but the reflection
from the bottom of the water.
There are various kinds of lens and they may be classed as:
1. Convex.
o. double convex;
h, piano convex;
c. ooncavo convex.
Concave.
a. double concave;
6. piano concave;
c, convexo concave.
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These various types of lens are illustrated in fi^. 3,778 to 3,7S3»
which give a better idea of the numerous combinations of curved and
plane surface than is obtained by definition.
FK36. 3.778 to 3.783.— Various lenses. The firat three are thicker at the center than at the
borders, and are called converging; the second three, which are thinner at the center are
called diverging. In lenses whose two surf aces are spherical, the centeis of these surfaces
are called centers of curvature, and the right line which i>asses through these two centers
is the princii>al axis. In a plano-concave or plano-convex lens, the principal axis is tiie
peipendicular let fall from the center of curvature of the spheric^ face on the plane face.
Pigs. 3,784 and 3.785. — ^The principal focus. By definition, it is, that point where all ths rays
parallel to the i)rincipal axis meet after reflection, as, for instance, the rays from a source of
ught at an infinite distance from the mirror. The sun is so far distant that its rays are
practically parallel. When they arc reflected upon a concave mirror they are reflected to
the princip^ focus P; forming a point of intense light and heat.
Foci in Double Convex Lenses. — The focus of a lens is the
point where the refracted rays, or their prolongations meet. Double
cx)nvex lenses have both real and virtual foci, like concave mirrors.
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Principal Foci.— Fig, 3,786 shows the csase in which the luminous
rays whidi fall on the lens are parallel to its principal axis.
In the figure, any incident ray as LB, in approaching the normal of
the point oi incidence B, and in diverging from it at the point of emerg-
ence D, is twice refracted toward the axis which it cuts at F. Since all
rays parallel to the axis are refracted in the same nmnner it can be
Fig. 3,786. — Principal focus in double convex lens. CASE I: Rays jrom luminous source
parallel to the principal axis.
Pig. 3,787. — Conjugate foci. By definition, when two points ar^, so related that object and
image may exchange places^ they are called conjugate foci. If a luminous object be placed at
the point O, it orojects divergent light rays upon the mirror. These rays will focus at a
ix»int I, a little further from the mirror than the principal focus P. If the source of light be
now placed at I. the rays will pass back over the same paths and will come tc a focus at O;
the i>oints I and O thus related to each other are called conjugate foci. Concave mirrors
make divergent rays less divergent, parallel or convergent; parallel rays, convergent;
convergent rays more convergent.
shown by calculation that they all pass very nearly through the point P,
so long as the arc DE does not exceed 10° to 12°. This point is the
principal focus and the distance FA, the principal focal distance.
Fig. 3,788 shows the case in which the luminous source is outside
the principal focus, but so near that all incident rays form a diveigent
pencil. ^ ^
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Virtual Foci, — A double convex lens has a virtual focus when the
luminous object is placed between the lens and the principal focus ^ as ^own
in fig. 3,790.
In this case the incident rays make with the normal greater angles
than those nmde with the rays FI from the principal focus. Accordingly,
Fig. 3,788. — Principal focu» in double ctirve lenses. CASE II: Divergent rays from luminous
. source. In the figure the luminous source being at L, by comi>aring the path of a diverging
ray LB, with that of a ray, SB, parallel to the axis, the former islound to make with the
normal, an angle LBN, s^ter than the angle SBN, hence, after traversing the lens, the
ray cuts the axis at a pomt L', which is more distant than the principal focus P. As all
rays from the point L mtersect approximately in the same point L', this latter is the con-
jugate focus of the point L . This term has ^e same meaning here as in the case of mirrors,
cmd expresses the relation existing between the two points L and L', which is of such a
nature that, if the luminous i>oint be moved to L', the focus passes to L.
and therefore the reflected ray M £ diverges from the axis AK. This is also the case with all
rays from the point L, and hence these rays do not intersect, thus forming no conjugate
focus. If tibuey be regarded as being prolonged on the other side of the mirror, their pro-
longations wiU intersect in a point L', on the axis, giving the same effect to the eye as
though the rays were emitted from the i>oint L', this i>oint being called the virtual focus.
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when the former rays emerge, they move farther from the axis
than the latter, and form a diverging pencil HK, GM. These rays
cannot produce a real focus, but their prolongations intersect in some
point L , on the axis, and this point is the virtual focus of the point L.
Foci in Double Concave Lenses. — In lenses of this form,
there are only virtual foci, whatever be the distance of the object.
Fig. 3,790. — ^Virttial focus in double convex lens. In the fifrure, L is the ];>osition of the luminous
source between the principal focus and the lens; F is the principal focus, and L', the virtual
focus corresponding to the position L of the luminous source.
Fig. 3J01. — ^Pod of convex mirrors. This type of mirror has odv virtual focL Let SI, and TK
be rays i>£uallel to the principal axis of a convex mirror. These rays, after reflection^ take
the diverging directions IM, KH, which, when continued, meet at a i>oint P, which is the
principal virtual focus. In the triangle CKF, it may be shown, in the same manner as
with concave mirrors, that the point P is approximately the center of the radius c^ curva-
ture CA. If the incident luminous rays, instead of being parallel to the axis, proceed from
a point L, situated on the axis at a fimte distance, a virtual focus will be formed at a point
L • between the principal virtual focus and the mirror.
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In fig. 3,792 let SS' be any pencil of ray parallel to the axis. Any
ray SI is refracted at the point of incidence I, and approaches the
normal CI. At the point of emergence it is also refracted, but diverges
from the normal GC, so that it is twice refracted in a direction whidi
moves it from the axis CC. Since the same conditions obtain for
every other ray, S'KMN, it follows that the rays, after traversing the
lens, form a diverging pencil, GHMN. Hence, there is no real focus,
but the prolongations of these rays cut one another in a point F, whidi
is the principal virtual focus.
5 =- 7^
Pi<S. 3,792. — ^Virtual focus in double concave lens. CASE I : Parallel incident rays.
Fig. 3,793. — ^Virtual focus in double concave lens. CASE II: Divergent incident rays. In this
case where the rays radiate from a point L on the axis, it is found by the same construction
that a virtual focus is formed at L', which is between the principal focus and the lens.
Experimental Determination of the Principal Focus of
Lenses. — To determine the principal focus of a convex lens, it
PlC- 8,794. — ^Effect of placing luminous source at the principal focus of a double convex lens.
As the point of light comes near the lens, the convergence of the emergent rays decreases,
and the conjugate focus L' (fig. 3,788) becomes more distant. When the source of light L
coincides with the principal focus F, as shown above, the conjugate focus is at an infinite
distance, that is to say, the emergent rays are parallel- When this condition obtains, the
intoisity of light decreases slowly, thus, a small lamp can illuminate considerable distance.
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may be exposed to the siin's rays so that they are "paraller* to
its axis. The emergent pencil being received on a ground glass
screen, the point to which the rajrs converge or the principal
focus is readily seen.
Fig. 3,795 shows the exp2 imental determination of the principal focus
of a double concave lens.
Fig. 8,795. — ^Experimental determination of the principal focus of a double concave lens. The
face AB is covered with an opaque substance, such as lamp black, two small apertures. A
and B. being left in the same principal section and at an equal distance from the axis.
A pencil of sunlight is then received on the other face, and the screen P, which receives the
emergent rays, is moved toward or away from the lens until A and B, the spots of lisdlt
from the small apertures, are distant from each other by twice A'B'. The distance Dxis
then equal to the focal distance FD, because the triangles FA'B' and FAB are similar.
Optical Center; Secondary Axis. — In or near every lens
there is a point called the optical center, which is located on the
axis, and which has the property that any luminous ray passing
through it experiences no angular deviation, that is to say, the
emergent ray is parallel to the incident ray. The existence of
this point is demonstrated as in fig. 3,796.
By definition, a secondary axis is any right line (as PP', fig. 3,797),
whi<:k passes through the optical center of a lens without passing through
the centers of curvature. From this property of the optical center, every
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2,691
PzG. B,796.^-Optieai center. Let two parallel radii of curvature CA and C'A' be drawn to
the two surfaces of a double convex lens. Since the two plane elements of the lens A and A'
are parallel, as being perpendicular to two parallel right fines, it is evident that the refracted
ray AA' is propagate in a medium with parallel faces. Hence a ray KA, which reaches A
at such an mdination that after refraction it takes the direction AA', will emerge parallel
to its first direction. The point O at which the right line cuts the axis is therefore the
optical center. The position of this point may be determined from the case in which the
curvature of the two faces is the same, which is the usual condition, by observing that the
triangles COA and C'OA' are equal, and therefore that OC — OC, which gives the point
O. If the curvatures be unequsJ, the triangles COA and C'OA' are similar, and either CO
or CO may be found, and therefore also the point O. In double concave or concavo-
convex lenses, the optical center may be determined by the same construction. In lenses
with a plane face, this point is at the mtersection of the axis by the curved face.
Pig. 3,797. — Secondary axis. This is any right line passing through the optical center, but not
through the centers of curvature. Rays emitted from a point F on the secondary axis PP'
nearly converge to a center point P' on the axis PP', and according as the distance from the
point P to the lens is greater or less than the principal focal distance, the focus thus formed
will be conjugate or virttud. The formation of image is in accordance with this principle.
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Pig. 3,789. — Image in convex mirror. Let AB be the object; draw two lines from A, and two
from B, to the convex side of the mirror. Draw lines from C through these points. These
lines are the normals. Construct the angles of reflection and extend the rays imtil they
meet. It is foimd in this case that the image A'B' is virtual, erect, smaller than the object,
and located on the opposite side of the mirror. The effect of a convex mirror is to noake
convergent rays less convergent, parallel, or divergent; parallel rays, divergent, and
divergent rays, more divergent, in general, the concave mirror tends to collect the rajrst
and the convex mirror tends to scatter them.
Fig. 3,799. — Formation of real image by double convex lens. Let AB be placed beyond ihe
principaliocus. If a secondary axis AA' be drawn from the outside pomt A, any ray AC
from this point will be twice refracted at C and D, and both turning m the same directioO|
approaching the secondary axis, which it cuts at A', the other rays from the point A will
intersect in the point A' which is accordingly the conjugate focus of the point A., If the
secondary axis be drawn from the point B, it will be seen that the rays from this point
intersect in the point B', and as the points between A and B have their foci between A'
and B', a real and inverted image of AB will be formed at A'B'. To see this image it may be
received on a white screen, on which it will be depicted, so the eye may be placed in the
path of the rays emerging rrom it. Again, if A'B' were the luminous object, its image would
be formed at AB. - o
MOTION PICTURES 2,693
seoondaxy axis represents a luminous rectilinear ray passing from this
point because, from the slight thickness of the lens, it may bfe assumed
that rays passing through the optical center are on a right line.
Formation of Images by Double Convex Lenses. — In
lenses as well as in mirrors, the image of an object is the col-
action of the foci of its several point. Accordingly images fur-
nished by lenses are real or virtual in the same case as the foci,
and their construction resolves itself into determining the posi-
tion of a series of point.
"-*^A
Pig. 3.800. — ^Formation of virtual image by double convex lens; object AB, placed between the
lens and its principal focus. If a secondary axis OA' be drawn from the point A, every ray
AC, after having been twice refracted, diverges from this axis on emer8[ing, since the pomt A
is at a less distance than the principal focal distance, this ray, continued in an opposite
direction, will cut the axis OA'^in the point A', which is the virtual focus of the pomt A.
Tracing the secondary axis of the point B, it will be found in the same manner, that the
virtual focus of this point is formed at B'. There is, therefore, an image of AB at A'B'.
This is a virtual image; it is erect and larger than the object. The magnifying power is
greater in proportion as the lens is more convex, and the object nearer the principal focus.
Pig. 3,799 shows the formation of a real image, and fig. 3,800, the
formation of a virtual image.
Ques. Describe the image formed with object at twice
the focal distance.
Ans. The image is real, inverted, same size as the object,
and at the same distance from the lens. ^
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o « :§
^ O-^ i^ El U
Ques. Describe
image formed
with object at
more than twice
focal distance.
Ans. The image
is real, inverted,
smaller than the
object, and beyond
the principal focus.
Ques. Describe
image formed
with object at less
than twice the
focal distance and
greater than focal
distance.
Ans. Image is
real, inverted, larger
than the object, and
more than twice the
focal distance from
the lens.
When the object
is at the principal
focus, the ra3rs after
passing through the
lens will be parallel,
and no image will he
formed.^
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Ques. Describe image formed when the object is be-
i*ween the principal focus and the lens.
Ans. The image is virtual, erect and larger than the object.
In this case the rays are made less divergent but not convergent.
Formation of Images by Double Concave Lenses. — These
lenses like convex mirrors give only virttial images^ whatever
be the distance of the object.
Pig. 33O6.— Fonnation of virtua limage in double concave lens: no real image is formed with
this type of lens. Let AB be an object placed in front of the lens. If the secondary axis
AO be drawn from the point A, all rays AC, AI, etc., from this point are twice refracted in
the same direction, diveraing from the axis AO, so that the eye receiving the emergent ravs
DB and GH, supposes them to proceed from the i>oint where their prolongations cut the
secondary axis AO in the point A'. Similarly, drawing a secondary axis from the point B,
the rays from this point form a pencil of divergent rays, the directions of which, prolonged,
intersect in B'. Accordingly the eye sees at A'B', a virtual image of AB, which is always
trect, and smaller than the dbjecL
Ques. How are rays affected by double concave lenses?
Ans. Diverging rays are always made n:iore divergent.
Ques. Desoibe the image formed.
Ans. It is virtual, erect, and smaller then the object. [^
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Formulae Relating to Lenses.— In all these lenses the re-
lations between the distances of the image and object, principal
focus, also radii of curvature, the refractive index, etc., may be
expressed by a formula.
If O be distance of the object from the lens, I the distance of the
image, and F, the principal focal distance, then
Fig. 3,806. — Spherical aberration. The reflected rays of concave spherical mirrors do not meet
at exactly the same point. For instance, the ray AB, will be reflected to F, but DE will be
reflected to H, a point closer to the mirror. This is called spherical aberration. It has been
observed that the reflected rays only pass through a single point when the ai)erture of the
mirror does not exceed 8 or 10 degrees. A larger aperture causes spherical aberration,
I)roducin^ a lack of "sharpness." Every reflected ray cuts the one next to it, and their
points of mtersection form in space a curved surface which is called the caustic by reflection.
By experiment, when the light of a candle is reflected from the inside of a tea cup or a glass
tumbler, a section of the caustic surface can be seen by partly filling the cup or tumbler^ with
milk, spherical aberration may be avoided by the use of a parabolic mirror. The point C
is the center of curvature.
From the equation it is seen that if any two of the distances are
given the other can be found. Thus solving (1).
I
O
F
F
2_
o •
o *
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(2)
(3)
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Spherical Aberration; Caustics. — The assumption that
rays emitted from a single point intersect also after refracting
in a single point is virtually correct with a lens whose aperture,
that is, the angle obtained by joining the edges to the principal
focus, does not exceed 10° or 12°.
Ques. What Is the effect of a larger aperture?
Ans. The rays which traverse the lens near the edge are
refracted to a point F on the principal axis nearer the lens than
the focus of the rays G which pass near the axis.
FOCUS OF INTERMEDIATL RAYS
Pig. 3,807. — Effect of aphericai aberration: it produces a lack of sharpness and definition of
an image. If a ground glass screen be placed exactly in the focus of a lens, the image pf an
object will be sharply defined in the center but indistinct at the edges, and if .shairjj at the
edges, it will be indistinct at the Center. This effect is very objectionable, especially, in
photographic lenses. To avoid this, a disc D with a hole in the center is placed concentric
with the principal axis of the lens, thus only the central part of the lens is Used.
That is to say, the rays farther f rbm the principal axis are refracted
more than those near this axis.
Ques. What ill effect is due to spherical aberration? . ;
Ans. The image is slightly blurred.
Ques. How may this be avoided?
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HAWKINS ELECTRICITY
Ans. By means of a "stop/* that is to say, a disc with a
small hole in it placed in the path of light, as shown in fig. 3,807.
Ques. What name is given to the luminous surfaces
produced by the intersecting of the refracted rays?
Ans. Caustics by refraction.
PicTSpSOSh — Experiment illustrating the dispersiciii or decomposition by rEfractionof^liilt
%ht. If a pencil of the fiiin 3 rays SA be idlowfti to pass through & small aperture in the
window shutter nf a dark chamber, this pencil tends to fonn around and colrjrleaa Im&eeof
the Bua at K, but if a flint glass pnam arrangEd faorisontally, be interposed in its path, the
beam, on emerging from tbe prism. becf3)m^ refracted toward its base ^ and product* on a
distant screen a vtjrtical band rounded at the ends, colored in all the tuntJ of the rainbow,
which u called the &jlat epectnim. Ta thia spectrum there 13 virtually an infinity of
different tint, which niet?te into each other, but it iacuftomary to distinijTjJsh sev^n pnnd-
pat colore, vi^: violet Jndlgo. blue, green. yellQW, orange, red; they are arrajigod m this
order in the spectrurn, the violet bemg the most refrangible, and the red the least. They
do not all occupy an equal extent in the spectrum, violet haTing th« greatest extent, ajod
onuigethi^ least.
Gfaromatic Aberration. — ^When white light is passed through
a spherical lens, both refraction and dispersion occur.
This causes a separation of the white light into its various colors and
causes images to have colored edges. This defect which is most observa-
ble in condensing lenses is due to the unequal refrangibility of the simple
colors, and is ouled chromatic aberration.
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2,699
Ques. What is white light?
Ans. The light from the stin, the electric arc, etc.
Ques. What is dispersion?
Ans. The decomposition of white light into several kinds of
light as shown in fig. 3,?
^C 3,^Q. — Adiromatic lens» con^iisting of a. combination of a double convex lena of crOWtt
gla^t and a double concave lens of flint glass. Whenever it is desired to project especiaUy
good pictures upon a screen, lenses are often combined as shown in the figure. Here M
indicates the line through the principal axis, at which the red rays reflected by the double
convex lens would strike, and S, the line where the violet rays would be projected. The
addition of the double concave lens brings the red and violet together again at G. A com-
bination of two such lenses F H, placed uie proper distance apart and the surfaces properly
prc^ortioned, may be made to combine any two of the colors of the spectrum. Accordingly
even with these connected lenses there is always some coloring on the screen, although,
hardly noticeable.
FUS. 3310 to 3,812.~Various achromatic lenses. Pig. 3,810 and fig. 3,811 are types usuaUr
used in photography, and fig. 3,812, a combination used in motion picture and stereopticos
I>rojection.
Achromatic Lenses. — The color effect caused by the chro-
matic aberration of a simple lens greatly impairs its usefulness.
This may he overcome by combiniiig into one lens, a convex lens of
crown glass and a concave lens of flint glass*
Ques. What is the action of the first lensb^Coogle
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Ans. It pixxiuces both
bending and dispersion.
What is accom-
by the second
com-
Ques.
pushed
lens?
Ans. It almost
pletely overcomes the dis-
persion without entirely
overcoming the bending.
Principles of Optical
Projection. — ^The process
almost the reverse of
IS
ordinary photography.
For instance in photograph-
ing a scene by means of the
photographic objective or lens,
a reduced image is obtained on
ground glass. This glass is
replaced by a sensitiz^ plate,
and by the use of chemicals
the image is fixed thereon.
In projection the process is
reversed, that is, a transi)arent
slide is made from the picture
made with the lens, or the roll
of film taken with a motion
picture camera is developed
and used in the projection
lantern or "motion picture
machine" as it is usually
caUed.
By means of a condensed
light these are strongly illumi-
nated, and with an objective
lens, an enlarged image is pro-
jected upon the screen; tLis
screen image corresponding to
the real objects, photographed.
MOTION PICTURES 2,701
The principles of optical projection for both lantern slide and
motion picture apparatus will readily be understood from the
diagram fig. 3,813.
At E is an electric light or other suitable illuminant the light from
whidi is caught up by the condensing lenses or condenser C; this
condenser is an arrangement of lenses so constructed as firstly, to gather
up as great a volume of light as possible and secondly, to concentrate
t£e light which it gathers at the center or diaphragm plane of the ob-
jective when the (S)jective is located at the proper distance from the
slide or film, which distance is determined by the focal length of the
objective.
The slide or film should be placed at such a point that the entire area
of the opening is fully illuminated, and it should also be placed so that
the greatest number of light ray possible should pass through it. Taking
into consideration the fact that the opening in the mat in the lantern
slide is 2% X3 inches and in the motion picture fikn is % X^^
inches, it will at once be evident that the slide must be placed at the
point D in the diagram in order that its entire area be covered, ^d the
moving picture fikn must be located at the point F, in order that it may
take in the greatest nxmiber of light ray.
^ Proceeding from the slide or film, the light passes through the objec-
tive O, where the rays cross and the object is ther^ore reversed; by
means of the objective, the object is also imaged or delineated upon the
screen S, the d^[ree of sharpness or flatness of the image depends upoa
the optical connection of the lens.
Ques. What must be the relative positions of the ore,
condenser and objective?
Ans. They must be so placed ^hat an image of the light
source will be formed at the diaphragm of the objective.
Under these conditions all light coming from the condenser is utilized
and the image on th6 screen is at its bnghtest.
Ques. What provision should be made where lantern slide
and motion picture films are to be used interchangeably?
Ans. Since the opening in the slide mat is approximately
three times that of the moving picture film, it is therefore necessary
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HAWKINS ELECTRICITY
to have a lens for lantern sl-.des about three times the focal
length of that of the lens used for films.
It should be noted that it is possible to match the size of the image
in one dimension only (either width or height) because the two openings
are not proportionate in size; accordingly, it is necessary in ordering
lenses to specify whether the images are to ^ the same height or width.
How to Select a Lens. — The lens is probably the most im-
portant consideration in projection work, for on its selection
depend the quality and size of the image on the screen. Not
9)Kii 3314. — ^Bausch & Lomb standard projection lens. It coftai»t» of two combinations fitted
into a cell and mounted in a brass tube which slides through a brass tube or sleeve. The
focusing is by rack and prism, as shown. Connection is made for spherical and achromatio
aberration. Equivalent focus 2^ to 32 inches, and back focus In to 30 inches; oorree-
ponding diameter of lenses IH to 2%. ^
the lens mounting, nor even the diameter of the lens itself, but
its equivalent focus, and distance from the screen^ determine
the size of the image.
Ques. At a given distance how does the size of the
image on the screen vary with the focal length?
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2,703
Ans. The greater the focal length the smaller the image.
Accordingly short focus lenses give large images.
Ques. What precaution should be taken in selecting
a lens?
Ans. The lens should not be of such short focus that the
magnification will be so great as to sacrifice definition and
perspective when viewed by an observer near the screen.
Figs. 3^15 and 3.816. — Two forms of condenser. Owinsr to its form, the meniscus condenser
will intercept and utilize a larger percentage of light ray from the arc than the piano,
which means that more light will be transmitted to the film, when a meniscus condenser is
used. The meniscus, however, because of being closer to the heat of the arc, is more liable
to breakage. A combination consisting of one meniscus, and one bi-convex condenser is
recommended.
Ques. What kind of picture is most desirable?
Ans. Brilliant pictures of medium size.
Ques. How should the projection distance be measured?
Ans. From the slide or film to the screen.
The accompanying tables show the size of image obtained with
lenses of different focal length at varying distances. Other sizes, focal
lengths and distances can be computed as follows: ^
2,704 HAWKINS ELECTRICITY
Size of Image. RULE: Multiply the difference between the
distance from the lens to screen mid the focal length of the objective ^
by the size of the slide and divide the product by the focal length.
EXAMPLE. — ^Let L be the projection distance, 40 feet or 480 inches;
S, the slide mat 3 inches; F, the focus of the lens 12 inches. The
formula for size of image, is
^_ S (L-F)
a g
where d^^ze of image substituting the given data
, 3(480—12) ,,». ^...^
"~^ — 12 ^ = 117ins. orOJ^ft.
Focal Length. RULE: Multiply the size of the slide or
film opening by the distance from the lens to screen, and divide the
product by the sum of the size of the image and the size of the slide.
Expressed as a formula
P_SXL
substituting the values previously given
^_ 3X480 1,440^^^.
^^117T3^l20"^^'^'-
Distance from Slide to Screen. RULE: Multiply the
sum of the size of the image and size of slide mat, by the focal lengthy
and divide this product by the size of the slide mxit.
Expressed as a formula
, F ((f +S)
S~
substituting the values previously given
^ ji (m+s) w^stis.9?i»#
MOTION PICTURES
2,706
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2,706 HAWKINS ELECTRICITY
Motion Picture Machines. — ^The term motion picture
machine is the proper name of the apparatus used in projecting
motion picture film upon a screen; the use of such expressions
as projector, graphoscope, etc., should be avoided.
The function of a moving picture machine, as stated, is to project
motion pictures upon a screen, in distinction from a motion picture
camera used for motion picture photography. Some of the coined
expressions" are both ill advisedly and erroneously used.
A motion picture machine may be said to consist of:
1* An optical system, comprising
a. Source of light;
r condenser;
[ objective.
b. Lens { f?«denser;
2. Intermittent film feed system, comprising
a. Upper reel; g. Shutter;
b. Upper steady feed sprocket; h. Lower steady feed sprocket;
c. Steady drum; i. Lower reel;
d. Film gate; j. Lower reel drive;
e. Intermittent sprocket; k. Operating crank and drive;
/. Intermittent movement; /. Ntunerous presser rollers.
Besides these various essential parts, safety devices such as, fira
shutter, fire valves, film shields, etc., are provided.
The elementary moving picture machine shown in fig. 3,819
is so drawn that every part can be seen; it does not represent
any particular machine but is intended to give a clear idea of
how the film is fed across the film gate intermittently and the
synchronous operation of the shutter whereby the light is cut
off from the screen during each movement of the film, with
alternate **on** intervals while the film is at rest.
Ques. Upon what property of vision is moving picture
projection based?
Ans. Upon the '^persistence of mi^w.^^Q'^'^^^^y^O^S'^
MOTION PICTURES
2,707
■^ » K =J dJ5^s g
£61
*-■ a t; ■* rt " o'"
by Google
2,708
HAWKINS ELECTRICITY
UPPER STEADY
UPPER fm^ F
PRlTHt G-EAR WHCE15
Pig. 8,819. — Elementary moving picttire machine without case, showing essential i>artt«
MOTION PICTURES 2,709
Ques. Define persistence of vision.
Ans. It is that property of the eye by which vision remains
or persists for a short interval after the thing viewed has vanished.
Owing to the persistence of vision, when two views are seen with an
interval of not more than one fiftieth of a second between the two, the
eye blends the two and accordingly does not appreciate the interval of
darkness which has occurred between the two, as is demonstrated in
moving picture projection.
Ques. Describe briefly the operation of the elementary
motion picture machine shown in 6g. 3,819.
Ans. By turning the operating crank A, counter clockwise,
the main shaft B,. is driven through the 4 to 1 reduction chain
drive D, a steady turning motion being caused by the fly wheel
C, this in turn operates the upper steady feed sprocket E,
through the 4 to 1 reduction gear F, thus the teeth of E sprocket
which mesh with the perforations in the film, feed the film at
a constant rate, the film being held against E by presstire roller G.
A film loop or length of loose film is thus maintained between E
and the steady drum H. The film is fed past the film gate
intermittently by the intermittent sprocket I, operated by the
Geneva movement K, the latter producing a quick quarter turn
of I, followed by a relatively long rest during which the main,
shaft B, makes one revolution. The barrel shutter L, by a
2 to 1 gear with the main shaft and proper timing, operates to
cut oflE the light rays from the screen dining each movement of
the intermittent sprocket I, and to admit the light during the
intervals that I remains stationary. The synchronous operation
of the intermittent sprocket and the shutter is very clearly
shown in the diagram. A lower steady feed sprocket M, which
operates at the same speed as the upper sprocket E, maintains
a lower feed film loop N, and feeds the fitei to the lower reel O,
Because of the increasing diameter of the roll of film due to
winding the film on reel O, the velocity of rotation of O must be
2,710
HAWKINS ELECTRICITY
Figs. 8,820 to 3,826. — Construction details of Simplex film gate. It is made of machine steel,
the Itags securing the gate to the holder being electrically welded. Pig. 3,820 represents
milled surfaces. The film trap shoes (figs. 3,820, 3,825), are of steS ground on both
sides and beveled (fig. 3,820) to permit slidmg into the dove tail slots (^. 3,823). The
lateral guide rollers (fig. 3,824 and 3.826) are of steel hardened and ground: the
film cannot pass the gpiide rollers unless it be set between the two. If it should not be. it
automatically rights itself. The distance between the rollers is adjustable by a set collar
(fig. 3,826). The gate (fig. 3,825) is opened for threading by a light inward pressure on a
thunble (fig. 3,826), and is closed by releasing the film trap door trip lever (fig. 3,825).
Thus, in ureadixig, there are only two operations: one to open, and one to close the
mte. The interxmttent sprocket tension shoe is made of ten pieces of hardened tool steeL
The two inside shoes are offset and do not touch the film. The cooling plate (fig. 3,826)
is made of two pieces of sheet steel separated K inch, which arrests the heat by radiation
and protects the fire shutter and aperture side of the film trap. The air space between the
film trap is H inch. r-^ r-^^r-
Digitized by VjOOQ .
MOTION PICTURES
2,711
allowed to vary; this is accomplished by means of the belt
drive P, the belt permitting slippage below the maximum speed.
It should be carefully noted that the total revolutions made by
each of the three sprockets E, I, and M, is the same, the only
difEerence being that the motion of E and M is constant while
that of I is intermittent.
Flos. 3,827 to 3,835. — Construction details of an intermittent sprocket and intermittent move-
ment. Pig. 3,827. intermittent sprocket and intermittent movement with case broken to show
interior; figs. 3,828 to 3,835, parts. ^ The intermittent movement is of the Geneva type
arranged to nm in oil. The case is in two pieces, consisting of box and screw cover, as
shown in fig. 3,827. "Framing" of the film is accomplished by advancing or retarding the
intermittent movement by a device for turning the intermittent box forward or backward.
The revolving shutter synchronizes automatically by a cam system.
Ques. What is the object of the upper and lower feed
loops.
Ans. To lessen the inertia of the film by reducing the length
of film subject to the sudden intermittent motion.
Ques. What duties are performed by the film gate?
Ans. It guides the film so as to prevent any lateral motion,
2,712
HAWKINS ELECTRICITY
flattens the film, and by frictional resistance, prevents the
momentum of the film causing any up and down vibration.
The Intermittent Movement. — Various devices have been
introduced for producing the intermittent movement necessary
in projecting motion pictures. The movement consists essen-
tially of an intermittent sprocket and intermittent gear.
The sprocket is a cylinder with teeth at each end, or for very light
construction, it may consist of two hubs provided with teeth and
^NiTIAL
CErfTRAL POSlTtOH
Of STATIONARY..
Pigs. 3,836 to 3,841. — Diagrams showing progressively the operations of the Geneiva tntef^
mittent movement. Pig. 3,836, approach of pin: fig. 3,837, initial position or beginning
of the movement; fig. 3,838, mid-position; fig. 3,839, final position or end of the move-
ment; fig. 3.840, recession of the pm; fig. 3,841, mid-position of stationary period. The
Geneva movement consists of a maltese cross M and a disc S provided with a pin P and
circular guide G. In operation, the pin disc S is in continuous motion and the pin is so
located ^at it enters one slot of the cross M and carries it along with it, thus causmg one-
quarter revolution. The circular guide G is cut away sufficiently to allow the cross to
make a quarter revolution, but when it registers with the cross it holds the latter securely
tmtil the pin rotates around to the next slot.
prcMperly; spaced on a shaft to take the fihn. The teeth mesh wMi
perforations of the film and thus secure a positive movement.
Of the various intermittent movements, the Geneva is extensively used
and ea^y tmderstood. Its operation is shown progressively in figs.
3,836 to 3,841.
Ques.
motion?
What is the nature of the Geneva intermittent
MOTION PICTURES
2,718
Pigs. 3,842 to 3,846. — ^"Threadiiuf'* a typical motian picture TnachiDe. Pig. 3,842 illustfatat
the metiiod of threading the nlm through thti film trap by fonQiaB the upper loop with the
second finger of the left hand and gripping iho film below the intermit tsnt Qprodkue with
the first finger. Pig. 3,843 illtistrates how the film is tbreaded through the film trap by
foraoing the upper loop with the second fintt r of the Mt hand and gtipping ths film below
the intermittent sprocket with the first and third fingers of the riirfit hand and closing the
film trap gate by tripping the film trip lever w ith Bccond finger. Tig. 3, §44 illustrated the
method of forming the lower loop, tiireadiriK the film over the lower feed sprocket and
closing the lower feed sprocket roll arm by a c] ow^n ward pn?^iirc with the first finger of the
right hand. The film is then inserted through the fire valve by means of the slot in the
hue of the mechanism and is then fastened .iri to tlie lawer reel so as to rfwind to th^iight^
Pig, 3,845 shows the machine completely threaded from the topign^i t^'thei ic^ldi^^jjirocket
through the film trap and on to the lower feed ^rocket and the take up reel, ^
2,714
HAWKINS ELECTRICITY
Ans. The motion begins slowly, (fig. 3,837), accelerates to
a maximum at the mid position (fig, 3,838) and gradually slows
down to zero (fig. 3,839).
2sm
Bvss, 3,846 to 3.855.— Simplex take up device. Pig. 3.846 belt drive for small reels; fis. 3,854«
chain drive for large reels ; fi^. 3,847 to 3,853, parts. The take up is the equivalent <» the belt
drive P, fig. 3.819, that is, it performs the same function, viz.: to rotate at variable speed
the lower reel upon which the film is wound. Instead of securing the variable speed by-
belt slippage, a triction disc clutch is provided. Part 260 is the driving side of the disc and
is directlsr connected to the take up shaft 684. The leather friction wauier 262 is 3' diameter
by ^* thick; it operates between friction disc 260 and pulley 260H' The driving pulley
260 j^, driven by belt 263 H, is forced to bear against leather washer 262 by sprmg 264«
which is kept in place by a thimble and set screw 265.
Ques. Describe a variation in construction details.
Ans. Insteadof only onepinonthedisc, there are sometimes two.
Ques. How may the relative periods of rest and motion
be varied ? Digitized by Google
MOTION PICTURES
2,716
Ans. By making the disc large in proportion to the cross.
The interval of movement can be reduced as much as desired in
proportion to the interval of rest, but the characteristic features o£
starting and stopping the film gradually will be lost directly in por-
portion as the ratio between disc and cross sizes is increased.
Ques. How is the Geneva moyement sometimes ar-
ranged in construction?
Ans. Provision is sometimes made for the movement to be
run in oil.
Fto. SJSS6, — ^Power's motion picture machine or Cameragraph; view showingkunp house and
machine with covers removed, exposing mechanism. i r^r\r-i
^^ Digitized by VjOOQ:
2,716
HAWKINS El,ECTRICITY
Illumination for Motion Picture Projection. — Both gas
and electricity are used to produce illumination formotion picture
projection. The electric arc is universally employed wherever
electric current is available, but in many rural districts where
Pig. 3,867. — Powers* intermittent movement. The driving element is a diamond^shaped
revolving surface which projects from the disc, the latter being attached to the main
spindle or shaft. A locking nng for the driven element is also formed on the face of the
msc in such relation to the diamond that the driven element passes from engagement with
the diamond to eng^agement with the ring. The driven element consists of a cross aa
shown with intermittent sprocket spindle formed out of a block of. drop forged tool steeL
The intermittent movement is arranged to run in oil.
electricity cannot be obtained, gas is used and gives satis-
factory results. Several kinds of gas are used for illumination.
Burners for use with these gases are shown in the accompanjong
cuts, also some types of generator or gas naaking outfit;
MOTION PICTURES
2,717
The Electric Arc. — ^The subject of electric arcs has been
presented at length in Gidde No. 9, and it is only necessary to
treat here of its special adaptation to optical projection.
The only modification of the ordinary arc required to adapt
. it for use in the optical lantern is to make it as much one sided
as possible, that is to say, to so arrange it that as much of the
light as possible will be thrown toward the condensers.
Pig. 3,858. — Challenge multi-tip acetylene burner. It has eight tips set in patrs at an angle.
The gas comes from each set at an upward and inward angle, meeting- to form one flame.
Ques. What kmd of current is used for the arc?
Ans. Either direct or alternating
Ques. How is the direct current arc connected?
Ans. The positive pole is connected to the upper carbon of
the lamp and the negative pole to the lower carbon.
Ques. How are the carbons adjusted for direct current
motion picture arc?
Ans. The carbons are placed end to end in a straight line
except that the axis of the lower one is slightly in advance of
that of the upper one as in fig. 3,859. To bring the maximum
light upon the condensers the carbon must be inclined about 26^.
2.718
HAWKINS ELECTRICITY
If inclined too much, the end of the lower carbon will throw a shadow
upon the condenser; if not enough, the maximum light is not projected
upon the condenser.
Ques. How are carbons adjusted for direct current
stereopticon arc?
Ans. The carbons are set at right angles, positive carbon
horizontal, and negative carbon vertical, as in fig. 3,860.
.POSITIVE CARBON
NEGATIVE CARBOI
CONDEMSER
CONDENSER
AXIS
Pig. 3.859. — Motion picture arc for direct current. The adwtnee dUpUaeemmnip lair H ^o^
causes the upper carbon to bum with a diagonal end containing the briUiant enter sod
causes the upper caroon lo oum wim a aiagonai enc
the lifi^t is accordingly thrown toward the condenser.
That is to say, the positive carbon is set in the axis of the oondeoGer
with the negative carc)on at right angles.
Ques. What troubles are encountered with altemathig
current arcs?
Ans. Two o-aters are formed and if the light from both is to
be used, a very careful setting and adjustment is necessary to
avoid poor illumination and a double spot at the center of the
screen. Digitized by CjOOQ
MOTION PICTURES
2,719
Ques. What kind of carbon should be used for alter-
nating current arcs?
Ans. Cored carbons.
Ques. For angular settings, how does the angle of
carbon vary?
Ans. It varies with the amotait of current used, and the size
and quality of the carbon.
C0NDEM5ER
AXIS
POSITIVE.
CARBON
NEGATIVE
CARBON
COIHOE-NSER
Pig. 3,860. — Stereopticon arc for direct current. This •etUng does not give &3 briUiimt an &rc
as fig. 3,869, when a long arc is used, but for a short arc the carbons bei::ome &a a&aj^ that
an arc of more brilliancy than fig. 3,859 is obtained.
Ques. In operation how is the proper angle secured?
Ans. By varying the angle, that is "rocking" the carbons
while watching the screen till the best illumination is secured.
Ques. How is the light centered?
Ans. By moving the arc in a direction opposite to that in
which it is desired to move the bright spot on the screen.
Ques. Describe the lamp adjustments.
Ans. There are four adjustments: 1, vertical, 2, lateral, 3,
focusing, and 4, feed. Digitized by Goog
2,720
HAWKINS ELECTRICITY
Ques. How is the arc started or ''struck?''
Ans. Bring the carbons together by turning the proper
knob, then reverse and draw them apart until the proper arc
IS secured.
Ques. What is a proper arc?
Ans. An arc ol medium length.
Fig. 3.861. — Pulco pastil adapter. By means of this device the Guil pastil may be used with
any calcium burner. The main portion of the adapter is a hollow shell which serves as a
zeceptacle for the pastil when not in use.
r"
Pigs. 3,862 to 3.865. — The Economic calcium light; makes its own gas automaticaUy L
oxone and ether. Pig. 3,863 shows section view of interior of outfit. The parts are:
main tank; L, cover for tank; . G, gas bell or chamber; C, container for holding c*-
oxone; R, wire rod for supporting container in position; O, needle valve oootrol
of oxygen gas direct to burner; H, needle valve controlling flow of gas through satutator
S which causes ether vapor (hydro-carbon gas) to flow to burner; S, saturator; I, Inkt
connecting with nipple of needle valve H; F, filler plug; X, overflow; B. bottom capol
wtwrator; p, pastil; N, ao^sle of bunjer, . . •
MOTION PICTURES
2.721
Ques. What are the characteristics of a long arc?
Ans. The crater is at less than maximum brilliancy and the
current is reduced.
Ques. How is the feeding of the carbon gauged?
Ans. By observation through the peep hole in the lamp
house, or by the sound produced by the arc.
Auxiliary Apparatus. — ^Various devices are necessary for
the proper and safe control of the electric arc used in motion
picture projection.
TILTtD STRAIGHT
"lET
CONDENSER
Pig. 3,866. — ^Arc setting for alternating cturent arc with cored carbons. When cored carbons
are used* the crater will form in the end of the core, keeping in the center of the carbon
pencil, and the vapor of the soft core will hold the arc between alternations. Without
cored carbons; an alternating current arc has a tendency to run to the nearer edges of the
carbons with loss of brilliancy upon the condensers.
Pic 3,867. — ^Tilted straight setting for alternating current arc carbons. The lower carbon is
placed a Uttle ahead of the upper carbon. This tends to draw the crater of the upper
carbon forward, thus improving the light on the condenser, but if the carbons be tilted too
much the lower carbon will obstruct light from the lower part of the lens. The carbons
must be in perfect alignment in a vertical plane, passing through the arc and axis of
condenser.
Each installation will require proper fuses and switches in accordance
with the Underwriters' regulations.
Rheostats are required with direct current to r^ulate the voltage so
as to obtain best results with the arc. Rheostats should never be used on
alternating current circuits for permanent installation as they are very
wasteful in comparison with transformers.
On alternating current circuits when it is considered that the hand
feed arc lamp used req^uires only about 30 to 35 volts, while the alter-
nating current is supplied at from 104 to 250 volts, it is obvious that
there is a large percentage of current wasted unless a transformer
having a proper transformation ratio be used. o
-2,722
HAWKINS ELECTRICITY
htk 8,868.-7-Niiiet3r degree or right angle arc lamp. With the 90** setting, the arc can be Icepd
nearer in line with the center of the lenses for a greater lenfi[th of time, without re-adjusting
ibe carbons, because of the horizontal carbon bemg placed in line with the principal opticu
axis and fed directly toward the center of the condenser.
##,##
Pigs. 3,869 to 3,876. — ^Bausch & Lomb diagrams illustrating the results of defective
centering, that is, the shadows produced. Successful results in projection depend
largely upcm the correct adjustment of the lamp^ which must throw a brilliantly
illuminated circle upon the screen. After the objective is focused, as will be evi-
denced by a sharpy clear image on the screen, remove slide and slide holder, and
examine the illuminated circle. If the light be centered and the lamp correctly
adjusted, the circle will be entirely free from coloration or shadows. In figs.
3,869 and 3,870, the crater needs to be properlv adjusted laterally, it being as
shown too far to the right or left: figs. 3,871 and 3,872, show fhe crater too high
or too low: in fijgs. 3.873 to 3,875, it is too near or too far from the condenser*
fiflT. 3.876 snows tt to be in correct oosition, the field being entirely dear.
MOTION PICTURES
2,72»
Fjc. 3,877. — Simplex arc lamp. The carbon holders are furnished to accommodate carbons of
W' to H* diameter and 12" upper and 6* lower in length, carrying capacity 75 amperes.
There are eight adjustments, six being accessible from the back of the lamp house; and
two, to alter the angle of the carbon, from the inside.^ The lamp can be withdrawn from
the back of the lamp house, so that all parts are readily accessible.
Fig. 3,878, Powers* arc lamp. Carrying capacity 100 amperes. All adjustments are accom-
plished from the outside of the lamp house. Carbon range from %" to H'' in diameter, 6*
leni^ for lower and 12* len^h for upper carbon. The carbon may be placed at any angle
desired, and can be moved mdependently of each other, forward, backward and sideways,
or the whole lamp can be swung forward or backward, laterally, and up and down.
2,724
HAWKINS ELECTRICITY
The Film. — ^This is made of celluloid, being similar to the
film used in ordinary cameras, excepting that it comes in long
strips, one thousand or more feet in length/
The size of each picture on the fihn is % inch high by iJlJ inch
wide. The fihn is IJ^ wide which leaves a margin on each side of
the pictures for the holes which mesh with the sprocket teeli. These
Figs. 3,879 and 3.880. — Powers' rheostats. The tvpe shown in fig. 3,879 is designed for use on
110 volt circxiits and will carry 25 a^^peres without overheatinc[. The coils are so supported
that any of them may be replaced when desired. Adjustment is effected by means of a lever
switch. Pig. 3.880 shows Underwriters' pattern rheostat of 25 amperes capacity. It is
designed for 110 volts and is not adjustable.
holes are about ^ inch apart. At present there is no standard as to
the spacing of the holes, but as in other Unes, the makers will sooner or
later adopt a standard.
Ques. How is film treated by the manufacturer before
shipment?
Ans. It is treated with glycerine.
This keeps the film phable, and delays drying out.
Ques. What precaution should be taken with film?
MOTION PICTURES
2,726
Ans. Because of its inflammable character it must always
be kept in fire proof enclosures.
Ques. How is film repaired?
Ans. Usually by cutting out the defective part and splicing
the ends together.
PlC 3.881. — ^Powers' multi-tap transformer. It is without casing and is mounted on heavy legs
which support it several mches above the floor. The numerous leads are properly marked
as shown, to distinguish them.
Ques. How is a splice made?
Ans. Cut one end on the line between pictures and cut the
other end with a quarter picture on; thus in cutting a film there
will be three quarters of a picture cut out, a picture and three
quarters, etc. Moisten the gelatine on the quarter picture and
scrape it dean, also scrape the celluloid side of the other end
2,726
HAWKINS ELECTRICITY
Pigs. 3382 to 3.884.— Various film perforations. These are called: fig. 3.882, round; fig. 3.883.
square: fig. 3^84. barrel. The square and barrel holes seem to be more durable than the
round nole. The shape of the holes should correspond to the shape of the sprocket teeth.
A standard perforation is four pairs of holes per picture, each hole being approximately
Vic X'/^, spaced along the edges of the film Mi inch, apart, making four holes at each edge lor
a H inch motion picture image.
Pig. 3.885. — ^The are controller of device designed to control the rate of feed of the carbons of an
arc lamp, with the object of maintaining at all times a predetermined size of arc It eoruittt
of the controller proi)er, direct coupled to a fractional horse power motor. There are two
shafts, primary and secondary. The former, which is du^ct coupled to the motor.
carries governor parts, and rotates constantly at the motor speed. The secondary, to
which the telescope rod is geared, remains idle until the speed of the primary shaft exceeds
the point of adjustment. The adjustment for any preferable size of arc is made with a brass
adjusting nut upon a rod projectmg from the cover of the controller. The ixmer end of the
rod is connected throtigh a heavy wire spring to a pawl, the. function of which is to "step
in" and transmit the power to the primary, through differential gearing to the secondary
shaft, at the slightest tendency of the arc to become wider than the predetermined sixe
adjusted for. The installation of the arc controller does not interfere with any of the
lamp adjustments already provided. The operator may trim as he pleases, and feed by
hand if he choose, by loosemng a thumb screw at the feed handle gearing. Having loosened
the thumb screw and trimmed the lamp, the operator strikes the arc by hand and makes
the original and only feeding adjustment, by parting the carbons to the size of arc that ha
wishes to maintain; he then tightens thumb screw, and sets adjusting nut at the controller
so that feeds do not occur below that size; the controller will then feed the carbons to that
certain size of arc without further attention. To increase size of arc. tighten adjusting
nuti to decrease size, loosen nut.
MOTION PICTURES
2,727
dean; Spreatd cement on the-dfeaned quarfer pictfufe space
and fit it on the back of the other end, stickhlg the two ends
together with the picttire lines matching and the sprocket
holes matching. Cut either through a sprocket hole or midway
between sprodcet holes straight across the film.
Fw. 3^86.— S^ce, in frame.
A, B, D, £, etc.. and
medianism, the framii^ ^
diatributicm of pictures and of sprocket holes as though no splice had been made. The
difference is found in the "iump" of the pictures when one or more pictures have been
"will not be disturbed a "
omitted, but the "frame"
1 as the splice passes.
Fig. 8,887. — Splice out of frame. The picture C has but three holes at the side. Hence, when
the picture B is pulled out of the fiun window ana C is pulled in, the intermittent sprocket
polltDgdown four holes will pull into the film window the three-quarter picture C, and also
ike top quarter of the whole picture D. At the next shift, the intermittent sprocket pulls
down another four holes, pulUng into the film window the remaining three-quarters of D.
and the top quarter of E, etc. This continues until the operator notices the screen and
frames with ma lever. This is called a splioe **oat of frame because the splice throws the
picture out of franw in passing. o
2,728
HAWKINS ELECTRICITY
Motion Picture Cameras. — ^Apparattis for taking motion
pictures differs in many ways from ordinary cameras. Pig. 3,888
is a diagram showing the essential parts of a motion picture
camera.
There are three compartments: 1, a front compartment U contaimng
a rotating shutter N, pin mechanism OP, and other parts not shown;
2, a compartment V, containing the fihn mechanism and magazines^
Vic 3,888. — Diagnun of motion pictuie camera sbowins the essential parts. Cameras are bttflt
for various ntunbexs of picture oer turn of the crank; four, dx, and eight are common.
An eight picture camera should be run at a speed of almost one hundred turns per minute.
To operate at this speed, get a watch ticking 300 ticks per minute and learn to count one,
two, three; one, two, three, etc., just as fast as the watch ticks, turning the crank one
revolution for every one, two, thzee counted; that is to say, one revolution per every
three ticks of the watch.
and 3, a comi>artment on the opposite side containing mechanism com-
municating with the spools in the magazines, with the sprocket wheels,
and the points in the first compartment.
The two magazines A, B, consisting of light boxes, fit into the back
portion, and carry reels, W, X, on wmdi the film is wound.
In operation, the roll of unexposed film L, which passes out of a
small aperture H' at the comer oi the toi> magazine A, around guide
rollers C, D, engages by its perforations with the sprocket wheel r, to
which it is kept by the roller E. The film forms a loop at H* and \
downward through the guide grooves made in the gate G. ^^
MOTION PICTURES
2,729
Continuing, it passes out past the bottom of the gate, forming a second
loop H', and then passes between a spring roller I and sprod^et J,
under the guide roller K. and enters at W the lower magazine B when it
is wound up on the bobbin X.
The sprocket wheels rotate continuously drawing the film from the
supply at L and taking it up at M.
Pica. 3,S89 to 3. 89 1. — Schneider motioa
pictuiro camera. Case at cnaho^any.
The film engaging device ta a. recipto-
catinji double pio movement* The film
bed lA covered with antiseptic velvet
ribbon, also the alummum film pressum
door which is adjustiLble to &ay desired
pnesBure, Two film retorts are fui*
nlshed haviiing Sl capacity of 200 feet of
film* There is a fiusb set take up
^indle and h film bobbin to wind ta«
nlm on » By lift! n^jf the self-dlosi njj door
on the side focusing device, only one
picture will be si^iled. There is a filai
counter dial which counts up to 300
feet* and can be set at aero for any
reading.
The motion of the film in the gate G, however, is intermittent. During
the period of rest, a surplus loop of film forms at H*, which is then puUeS
down through the gate by the action of the pin O, engaging wifii the
perforations.
The whole mechanism is so arranged and geared together tiiat,
while the film is being shifted, the light is excluded from the lens,
and admitted during the stcUionary periods.
2,730
HAWKINS ELECTRICITY
A long tube V extends throueh the center of the camera, and is provided
with a detachable cap at S. This tube forms the sight hole for inspecting
the image on the film, prior to exposure.
The gate G is a kind of hinged door with an aperture in it, and its
function is to keep the film flat and vertical during exposure and also to
act as a channel or guide. . .
mULSION SIDE .0F.F,tU4
Toward the leiis.
FILM
PRESSURE
DOOR
IT
iL
i;
SHUTTER
5ET SCREW
Fig. 3,892. — ^How to tise the Schneider camera. Open the dcwrs on both sides of the camera by
openmg locla, fill retort B in dark room with perforated, sensitive negative film A of reliable
tnanmacture. close cover and secure retort B, with nut, screw V into the camera box;
lead film A through film gate K of retort B in a way that theemulsion sideof fihnwfllbeup
jT over guide roller C. Now lead the film under guide roller D so the emulsion a'
of the film will lay against this roller D, then lead the mm over l^e sprocket R under the
two film pressure rollers £ and be sure that the teeth engage the holes in the film and not
between the holes, also make sure that the film lays straight over ^e large sprocket R
make a few turns of the sprocket to obtain more slack of film, lift pressure door G with the
ring finger of right hand and place the film straight into the aperture track, leave enough
slack for loop P and let the door go, but make sure that the door presses on the film. Now
leave enough slack for imder loop H and pass the film between sprocket and pressure
rollers L through retort gate K on to bobbin M of retort N. Make another turn of sprocket R
and see that the film is guided properly between all members and that the loops are there and
that bobbin M takes up the film. Place i;lie cover on retort N and fasten same into the rear
wall by rear nuts V, close all camera doors and aet the film counter to zero. The
camera has either a fixed or an adjustable focus lens (the latter preferred) either lens has a
diaphragm. The camera can be focused for either the inside or outside.
After taking a subject, the operator presses a button, and in so
doing pimches a hole in the film at a point just ^bove the gate, thus
indicating the end of the subject and beginning of the next subject.
MOTION PICTURES
2.731
Digitize!
Pigs. 3.893 to 3806.—
Views of Universal
motion picture cam-
era. Pig. 3,893 front
view showing lens» fly
wheel, shutter, and
aperture adjustment;
fig. 3895, right side
showing film channel
sprocket wheel and
shuttle movement.
The adjustable shut-
ter may be set for
from 25% to 60%
exposure. Under or-
dinary day light con-
ditions and ordinary
speed. 37 H% (about
Hoth second) is found
to be the correct time
of exposure; fig. 3.894«
left side showing ar-
rangement of take up
mechanism and stop
picture shaft.
2,732
HAWKINS ELECTRICITY
Ques. What requirement should be fulfilled by the
shutter?
Ans. It should be adjustable to give a variable ratio between
the open time and closed time.
Figs. 3,806and 3,89 7. — Exteriorand interiorvicws of Angelusmotionpicttire<^toera. Theframe
is made of pressed steel with table bronze bearings, claw movement is of the finger type,
counterbalanced, and feeds film forward or backward dually well. /Take up is. of uie
pulley type with spring belt and adjustable tension; takes up in both directions, forward or
backward. Punch or film marker is placed on one side so as to notch edge of film instead
of punching hole in center.
Ques. Can a motion picture machine be used as a
camera?
Ans. Yes.
Pictures may be taken by constructing a light tight box for the
motion head of the machine. Such an arrangement is, however, rather
bulky in comparison to a regular motion picttu*e camera.
Digitized
by Google
GAS ENGINE IGNITION 2,738
CHAPTER LXXV
GAS ENGINE IGNITION
Most treatises on ignition begin v^th an explanation of
electrical principles and considerable space is thus taken up,
which, if confined to the main subject, would be of greater value
to the reader, assuming that he either has an elementary knowl-
edge of electricity, or that he will acquire this knowledge else-
where.
The author especially recommends that the reader at least
acquaint himself with fundamental electrical principles before
taking up the study of ignition, so that he can, with greater ease,
become familiar with the working principles of the multiplicity
of ignition apparatus now in use. This preliminary knowledge
may be obtained by consulting the preceding Guides, however,
for convenience, a summary or condensed outline of elementary
electricity is here given.
Electricity. — ^The name electricity is applied to aa invisible agent
known only by the effects v^hich it produces, and the various ways in
vrtdch it manifests itself.
Electrical currents are said to flow through conductors. These offer more or less resistance
to the flow, depending on the materiaL Copper wire is generally used as it oifocs little xesistaace
to tiie flow of the current.
The current must have pressure to overcome the resistance of the conductor and flow,
. This pfessure is called vcMage caused by what is known as difference of pressure between the
•ouroeand terminaL
An electric current has often been compared to water flowing through a pipe. Thepressure
wider which the current flows is measured in volts and the quantity that i>a8ses in amperes^
Tbtb fwistaaoe with which the current meew in flowing along the conductor is measured in
o
2,734 HAWKINS ELECTRICITY
The flow- of tbe cnrrent Is pr opo rti onal to the voltage and inversely p ropo rti onal to tfat
resistance. The latter depends upon the material, length and diameter of the condtactor.
Since the current will always flow along the path of least resistance it must be so guarded
that there wfll be no lealoEMge. Hence to' prevent leakage, wires are insulated, that is. covered
by wrapping them with cotton or silk thread or other non-conducting materials. If the tn-
sulation be not ^ective, the current may leak, and so return to the source without doing its
work. This is known as a short circuit.
The conductor which receives the current from the source is called the lead and the ona
by which it flows back, the return.
When wires are used for both lead and return, it is called a metaXUe circuU; when the
metal of the engine is used for the return, it is called a grounded circuit, the term originating
in telegraphy, ^diere the earth is used fpr the return.
In ignition diagrams, then, the expression "to groond" means to the metal qf the engine.
An electric current may do work of various kinds, but the one p roper ty which makes it
available for ignition is the fact that whenever its motion is stopped by interposing a resistanoe.
tbe enerey of its flow is converted into heat. In practice this is accomplished m two ways:
1, by suddenly breaking a circuit; 2, by placing in the circuit a permanent air gap which the
current must jump. In either case, the intense heat caused by the enormous resistance inter-
posed, produces a spark which is utilized to ignite the charge. The first method is known as
uie ffnaM and 6reoA: or icw teiui6i» and the secoiid, the yimu» si^
An electric current is said to be: l,<f»rec<, when it is of imvarjring direction; 2, aUernaiinf,
^vfaea it flows rapidly to and fro in opposite directions; 3, primary, when it comes direct^
from the source; 4, secondaryt vrhea the voltage and amperage of a primary current have
txea changed by an induction coil.
A current b spoken of as fow ^«i»»on, or AI^A ^tfiufcm, according as the voltage is low or h^^
A hl^ tension current is capable of forcing its way against considerable resistance, whereas ^
A low tensicMi current must have its Paw made easy. A continuous metal path is cm easy one*
but an interruption in the metal, as, the permanent air gap of a spark plug, is^difiScult to bridge^
bemuse air is a very poor conductor. Air is such a poor conductor that it is usually* thoc^
«noneoualy, spoken oi as a non-conductor; it is properiy an insulator.
The low tension current is only able to produce a spark when parts are mx>vided in the
I>ath, so arranged that they may be in contact and then suddenlv 8q>arated. The low tenskn
current will, as tiie separation occurs, tear c^ very small metaUic particles and use these ae
a bridge to keep the i>ath complete. Such a bridge is called an are, the heat of whidi is used
lorigmtion.
Magnetlain. — The ancients applied the word "magnet," magnes
lapes, to certain hard black stones which possess the property of
attracting small pieces of iron, and as discovered later, to have the
stiU more remarl^ble property of pointing north and south when hung
up by a strii^; at this time the magnet received the name hdestone.
The automobue word magneto is derived, as may easily be understood,
from the word magnet.
Magnets have two opposite kinds of magnetism or magnetic poles, which attract or tegA
each other in much the same way as would two opposite kinds of dectrmcation.
One of these kinds of magnetism has a tendency to move toward the north and the other,
toward the south.
The two regions, in which the magnetic prcmerbr is strongest, are called the Poles. In
a long shaped magnet it resides in the ends, while afl around the magnet half way between
the ];>oles there is no attraction at alL The poles of a magnet are usually qwken of as north
pole and south pole.
When a current of electricity passes through a wire, a certain daange is produced in the
torxounding space producing what is known as a magnetic field.
If the wire be insulated with a covering and coiled around a soft iron rod, it becomes
an dectromagnet having a north and south pole, so long as the current continues tojiow. The
magnetic strength increases with the number ^ turn of the coil, for each turn adds m X
field to that of the other turns.
GAS ENGINE IGNITION 2,736
Induction. — ^If a second coil of wire be wound around the ooil of
an electromamet, but not touching it, an induced current is produced
in this second coil by what is known as inducUan, each time the Current
in the inside coil b^;ins or ceases flowing. The inside coil is called the
primary winding and the outside coil the secondary winding. Similarly,
the current passing through the inside coil is called the primary current
and that in the outside coil the secondary or induced current,
, It has been found that by varying the ratio of the number of turn in the two coils, the
xatio c^ volta^ of the two currents is changed approximately proportionately. That is, if the
primary windmg be composed of ten turns and the secondary, of one himdred, the volta^ of the
secondarv current is increased approximateljr ten times that of the primarj^. This principle is
employed to produce the extremely high tension current necessary with the jump spark method
oCigmtion.
Methods of Producing Electricity. — Currents are produced by,
1, chemical, and 2, mechanical means. In the first method, two dis-
similar metals such as copper and zinc called electrodes are immegrsed
in an emting fluid or dielectric. When the electrodes are connected at
their terminals by a wire or conductor, a chemical action takes place,
producing a current which flows in the external drcuit irom the copper
to the zinc This device is called a cell, and the combination of two or
more of them connected so as to form a unit, is known as a battery.
Tlie word battery is frequently used incorrectly for a single celL
That terminal of the copper electrode from which the current flows is
called a plus or fositioe hole and the zinc electrode terminal a negative
pole. It should be careiuUy noted, however, that the copper electrode
itself is negative and the zinc electrode, positive.
Cells are said to be primary or secondary accordmg as they generate a current of them-
selves or first require to be charged from an external source, stonng up a current supply ^diicb
k afterwards yidded in the reverse direction to that of the chaxging current.
Tliere are two methods of producing an electric current by mechanical means, 1, by a
diynaimo, and 2. by a magneto. A dynamo has an electromagnet which is known as a fidd
magnet to produce a magnetic field and an armature which when revolved in the magnetic
field develops electric current. A magneto has a permanent magnet to produce the magnetic
field and an armature which is usually arranged to revolve between the poles of the magnet.
The basic principles upon which dynamos and magnetos operate are the same.
Magnetos are divided into two classes, 1, law tension, and 2, high tension according as
thev generate a current of low or high voltage. Lrow tension magnetos are used for make
and break ignition and the high tension type for the jump spark sjrstem. There are numerous
so called high tension magnetos on the market each consisting of a low tension magneto in
oombinatipn with a secondary induction coil used to produce a high tension spark.
Ignition. — ^A thorough knowledge of ignition is of prime
importance to any operator of a gas engine, whether it be
stationary, marine, or automobile type. Many of the troubles
still encountered, notwithstanding ntimerous improvements,
have arisen from failure of the ignition system to p^orm its
proper function. The engine may operate with an inM)erfect
2J36
HAWKINS ELECTRICITY
fuel mixture, if the ignition system be in working order, but any
defect in the latter will in nearly every case cause the engine to
misfire or stop.
Numerous devices have been tried to fire the chai|;e in gas enfi:ines.
In the early days, a flame behind a shutter was used, the latter being
opened at the proper moment. ^ Sometimes the flame was blown out
by a too violent explosion, so this method gave way to a porcelain tube
that was kept at white heat by an interior flame. Tube oeing subject
to breakage, spongy platintun, heated by compression, was next tried
€Uid found to work, if not too moist from watery vapor in the gas mixture,
or if the engine speed were not too high. Electriaty is now universally
used. Hence, in order to gain an understanding of ignition principles.
liltMK£ANOBICM(
Fta. 8308 to 3.002. —Various methods of ignition. Pig. 3308. naked flame; fig. 8300. hot
tube; fig. 3.000. hot ball; fig. 3,001, low tension electric or make and break; fig. 8,002, high
tension electric or jump spark.
it is necessary to have at least an elementaiy knowledge of electricity,
as previously mentioned, and because of which, the preceding electrical
introduction will be f otmd of value.
Methods of Ignition. — ^The charge in fhe cylinder af a gas
'engine may be ignited in several ways, as
1. By means of a naked flame:
2. By means of a highly heated metallic stirfaoe;
3. By an electric spark;
4. By the heat of very high compressiox^g^.e^ by Google
GAS ENGINE IGNITION
2,737
The. naked flame is practically obsolete, and the hot surface or hot
tube is used to a very umited extent, except in the case of some types
of oil engine. Many builders of standard engine, however, are pre-
pared to furnish hot tube ignition.
Point of Ignition. — ^The "timing" or selection of the point
of the stroke at which ignition shall take place is an important
factor in the application of any method.
Obviously the amount of "advance," that is to say, the pre-dead
center angular position of the crank selected for firing the char^je, will
vary in^ff erent types of engine and in the same engine under dmereat
EXPLOSION LIME
POINT OF IGNITION
COMPRE55ION-CURVt
Fig. 8,003. — ^Indicator card for ^ras engine niustratins the **poirU of ignition**. It win be
noted that compression continued to the end of ue stroke, before we compression curve
made an abrupt change into a nearly vertical line, the point of ignition, that is, the
piston position at the instant of the spark, the nearly vertical "explosion" line with
the hifi^ peak coming almost to a i)oint, denotes a strong mixture and a quick explosion.
running conditions; thus, noting that there is an appreciable time
interval between the spark and the maximum pressure of combustion,
it is clear that the spark should be advanced more for an engine running
at high speed than for one running at low speed.
Ques. In general how much should the spark be ad-
vanced?
Ans. As much as possible, consistent with smooth running
and economy. o
2,738
HAWKINS ELECTRICITY
Ques. Why?
Ans. In order that the temp«:^ture at release, that is to say,
when exhaust begms, should not be high enough to injure the
exhaust valves.
If more attention were paid to this, especially by automobilists, there
would not be the need for such frequent grinding of the exhaust valves.
Pig. 8.90i.-— Sectional viev7 through valves of engine showing hot tube method of l^nitioii.
Tnis is a modification of the method described in the accompanjring text and is more
exact and satisfactory. In construction, a valve A, commomy called the timing valve,
is provided, and which is interposed between thie admission valve chamber B (coaf
mtmicating with the clearance space of the cylinder) and the interior of the hot tube C
This valve is normally held closed by the spring D. When the piston readies its inner
dead point at the end of the compression stroke, a cam B, on the secondary shaft, od&ob
the valve and allows a portion of the compressed charge to pass into the hot tube where
it ignites.. The timing valve is held open throughout the power and exhatut strokest
tiuis permitting the i»roauct8 of combustioa to be carried out of the tube with the exhatisL
GAS ENGINE IGNITION
2,739
Hot Tube Ignition. — ^This method consists of a short tube
of metal or porcelain which is maintained at a dull red heat by
contact with a gas flame, and which is attached to the engine
cylinder in such a manner that a portion of the explosive charge
is forced into it, this, being ignited by contact with the hot
walls of the tube, ignites the whole charge.
FkG. 8,906. — Meits and Weiss two cycle oil engine with hot ball igniter, in operation^ air
is drawn into the closed crank chamber A, from the interior of the base B, through the
part C, in the lower part of the cylinder. On the outward stroke of the piston, this air
IS compressed, and the opening of a port D, by the piston, allows the air, together with the
steam generated in the water jacket, to pass into the combustion space of the cylinder.
At the same time, the exhaust port E, havmg been overrun, and thus opened by the piston,
discharges the products of combustion of theprevious charge into the exhaust pipe. The
fuel is injected mto the cylinder by the pump P, and mixes with the air and steam previously
admitted frrom the csank chamber, so that on the compression stroke, the charge is CM]to^
lOaticaUy ignited by contact with the heated walls of the hollow igniter ball G. fSooa
tuL mane of cast iron, is located in the projection attached to the cylinder head, as shown.
A caiax|;e is eompressed aJc every revolution of tiie crank shaft, and compressed by the
pifltomnto the oonQwessionspagce of the cylinder and the interior of the igmter ball ^exe
it is ignited. Before starting, the igniter ball is heated for a few minutes by a small oil
burner M . The oil jet from the injection nozzle N , strikes the projection O , extending from
the igniter ball and is sprayed, vaporized and mixed with the air and steam in the compression
space. The igniter ball is maintained at a dull red heat by the heat of the explosives.
2^740 HAWKINS ELECTRICITY
In the Qrdinary arranfi^ment, the time of ignitiQa depcaids upon the
d^;ree <^ compression. The products of combustion remain in &e tube
and mix with the succeeding fresh charge, so that varying d^^rees of
compression cause ignition at different i)oints of the piston stroke or
cyde of operation. Under these conditions, the moment of ignition
becomes later and later as the amount of compression decreases, until
the compression becomes so weak as to produce failure to ignite.
Electrical Ignition Systems. — ^There is a mtdtiplidty of
method for using electricity for ignition. A classification of
these various system, wotdd divide them
1. With respect to the generation of the current, as
• a. Primary battery;
h. Storage battery;
c. Dvnamo;
d. Magneto.
2. With respect to the spark, as
a. Low tension;
b. High tension.
3. With respect to the nature of the sparking device, as
a. Make and break;
h. Jump spark.
4. With respect to the induction coil, as
a. Primary coil;
h. Secondary COU | ^frSu'(.ync/krono«. firnlfton).
5. With respect to the primary circuit control, as
a. Contact maker;
b. Contact breaker;
c. Mechanical vibrator;
d. Magnetic vibrator { SSS^iS^*"' „,,,,,, GoOgk
GAS ENGINE IGNITION 2,741
6. With respect to the magneto, as
a. Low tension;
b. So called high tension;
c. True high tension.
7. With respect to extra or duplicate apparatus, as
a. Dual;
b. Duplex;
c. Double.
8. With respect to circuit arrangement, as
o. One wire (grounded) ;
b» Two wire &ietalKc). *
9. With respect to special spark plug construction, as
a. Magnetic spark plug;
b. Coil spark plug;
c. Multi-point spark plug.
Current for Ignition. — ^The electric current used for igniting
the charge may be produced either by chemical, or mechanical
means, or it may be generated mechanically and stored chemic-
ally. The apparatus required for these various methods consist
of primary and secondary cells, dynamos and magnetos.
Primary Cells. — Two types of cell are in general use for
ignition, namely, liquid cells and the so called dry cells.
Liquid cells are used extensively for stationary engines and
for some classes of marine work.
In purchasing a set of wet cell, the following points should be noted:
1. They should be substantial and constructea so that the chemicals
•^jffll not creep over the edge of the jar or evaporate; 2, Th^ should
be slop proof and all renewals required should be easily obtainable.
When space allows and first cost is not of great importance, wet cells
give excellent service. The advantage of these cells is that they give
2,742
HAWKINS ELECTRICITY
Pigs. 3,906 to 3,909. — Hydraulic analogy ofeapaeitg. Pigs. 3,906
and 3,907 show two tanks of water of different sizes (capaci-
ties). The head of water is the same in each and consequenUy
the presstire in the stop cock is the same in each, irrespective
of the fact that they are of different capacities. The two dry
cells shown have the same voltage even though they are <n
different size. The difference in size, however, means that
they contain different amounts of electricit/. The voltage of
a dry cell does not depend on its size. It is about 1.5 volts
Pigs. 3,910 to 3,913. — Hydraulic analogy ofpreMure^ Pig. 3,910
shows three tanks connected in aeriea* The total head and
thior^ore, the pressure on the stop cock is three times that
of a single tank. When three cells are connected in series^ as
in fig. 3,911, the terminal voltage is increased three times, m a
like manner. Pig. 3,912 shows three tanks connected in
p^aHel. Here the pressure is the same as if there were only
one tank. When tluree cells are connected in paraUeh as in
fig. 3,913, the voltage remains the same as that of a single cell.
Pigs. 3.914 to 3,917.^ Hydraulic anal-
ogy of reaiatance. Pigs. 3,914 and
3,915 show two tanks, having equal
depths of water, and consequently
equal pressures in the discharge
cocks. The left tank has a small
cock {high resistance) and the other
has a laige cock (low resistance).
It is obvious that the flow from the
first will be less than the flow from
the second. In an analogous man-
ner it may be seen that the two dry
cell circtuts have equal voltages
applied and that the circuit of high resistance, (fig. 3,916),
permits less current to flow than does the circuit of low resist-
ance, fig. 3,917. It is apparent that both these conditions
show uie current to depend on the voltage and resistance,
in accordance with Ohm's law.
Pigs. 3,918 to 3,921.— Hydraulic analogy of current. Pigs. 3,918
* " * 'of the J
and 3,919 show two tanks with discharge cocks
size (equal resistances). Obviously the higher pressure in tank
fig. 3,918 will cause a greater flow through its cock than
will the low pressure in tank, fig. 3,919. The analogous
electrical condition is shown in figs. 3.920 and 3,921.
Assuming the internal resistance of each cell to be sero and
each circuit to have an equal external resistance, the current
in fig. 3,920 will be two times stronger than in fig. 3,921.
It anould be noted that in an actual circuit the internal re-
sistance of the cells must be considered. Thus, an anuneter
connected across the end terminals of the cells in figs. 3,020
and 3,921 will give the same reading because the internal resistance of a battery
of cells in series increases in proportion to the number of cell.
GAS ENGINE IGNITION
2.743
oonstant current,* moreover the liquid or electrolyte may;be renewed
so that it is not necessary to buy a new battery when it. becomes esC-
hausted.
**I>ry" Cells. — ^The so called dry cell consists usually of a
carbon and zinc element inamersed in moistened salts.
H15H POWER /'* *"'
LOW ROWER
LOW PRESSURE
LOW POWER
HIGH PRESSURE
Ags. 8,022 to 3,025. — Hydraulic analogy of nower. Figs. 3,922 and 3,023 show two taxJcs
inui equal news at different pressures. In both, the same number of pound of water is
discharged per second, but in the high pressure tank this amount is lifted higher than in
the low pressure tank, and consequently the first jet has moije power, because it raises
the same amotmt of water higher in the same time. Power, accordingly, increases with
pressure, as well as with flow. The electrical case is analogous. In fis. 3,924, the circuit
has 3 volts applied to two IH ohm lamps, thus, according to Ohm^ law, one ampere
is flowing. Pig. 3,925 shows a circuit having 1 H volts applied to one 1 H ohm lamp so
that here also one ampere is flowing. The candle power, however, of the two lamps
m flg. 3,924 is two times that of the lamp in fig. 3,925.
For full description of dry cell and points relating to same, see Guide
No. 1.
Since the gasoline engine has come into prominence and the demand
for an efl&cient, reliable and inexpensive source of current supply has
been created, the dry cell has been brought to a high state of efficiency.
An ammeter test should be made of each dry cell before purchasing.
The ignition size cell should test at least 25 amperes; to avoid waste of
current, make the ammeter test as quickly as possible.
Points Relating to Primary Gells.^-In order to obtain
satisfactory, results in battery systems of ignition, the following
suggestions shotdd be carefully noted and followed:
2,744
HAWKINS ELECTRICITY
Figs. 3,926 to Z,920»— Hydraulic analogy of 9Qitai dtpaeitioM
at different preeBureB, Theoretically, two batteries com*
posed of the same number of cell differently- arranged*
contain equal amounts of electrical ener^, but at different
voltages; just as two tanks may contam equal amounts of
water at different pressures, as is shown in figs. 8,926 and
8,927. This is awniming that the ceUs could be used till dead.
In acttial conditions, however, the oattery can only be run
down to a definite voltage, at which the apparatus ceases
to ^erate. Applying this to the two tanks in figs. 2,926 and
3.927, supposes they could be used until the levS fell to one
foot from the bottom, then, there would be more useless water
remaining in the left hand tank than in the other. In tiie
same way, if the batteries be discharged to the same end point, more unavailable energy
will remain in the left-hand than in the right-hand battery.
^GS. 3,930 to Z,9S3,~r Hydraulic analogy of tuefui aervice,
&^*vice is ustially expressed as the length of time a cell or
battery will continue to operate a given apparatus, that is
until the voltage falls to a definite value. It is evident that
with a lower cut off voltage more current can be obtained, jxist
as lowering the limit of the water level in a tank allows more
water to be withdrawn. It is also evident that the lighter the
flow from a given tank, the longer will be the service. Tliis is
true to an even greater extent in the case of dry cells on
account of the characteristic that the lower the current drain
the greater becomes the useful life. The length of service is
incr^sed, then, for two reasons; first, because energy is with-
drawn more slowlv, and second, because the capacity is increased. Thus, if the
drain be cut in half, the length of the service will be considerably increased.
current
Figs. 3,934 to 3,937. — Hydraulic analogy of parallel conneeffon.
Figs. 3,934 and 3,936 ^ow conditions of a sixigle tank, and
tm^ee tanks in parallel^ furnishing equal flows. It is apparent
that in the case of the i>arallel tanks, each is furnishing only
one-third the total flow, while the single tank has to nimish
it all. The parallel connection for dry cells has the same
effect of dividmg the current, giving triple the length of service*
Figs. 3,938 to 3,941. — Hydraulic analogy of recuperation. The
power of recui>eration and, some other phenomena may be
illustrated by an analogy in the form of such a tank as is
shown in fig. 3,938, contaming an internal diaphragm pierced
by a small hole. When the tank is in the condition of fig. 3,938,
with no water flowing, the pressure on the stop cock is due to
the head of water all the way to the top level. This corres-
ponds to the open circuit voltage of a cell. When, however, the
stop cock is opened, as in fig. 3.939 and water flows out of the
lower compartment faster than it can flow in from the upper,
the pressure immediately drops just as the voltage of a cell
droi)S imder a heavy current dram. The greater the flow the
•MTl-UNlTBA-nTRY L0N6 SCRVTf I
less of the total water in the tank that can be lised before the
lower (useful) compartment becomes exhausted. With a lighter
flow more opporttmity would be afforded to use water from the
upper tank, thus increasing the effective capacity. If now the
flow be stopped, the tank will "recuperate" to the condition of
fig. 3,940. so that it can once more be used, but the mitial
pressure" will be less than formerly and the recuperation after
a second discharge will not be as rapid as before. FmaUy, when
the upper compartment is emptied the recuperatrve power fails
altogether and the tank becomes "dead." In the case oi very
light flow from the lower chamber, as in fig. 3,941, therecupe-
ration may be able to keep up with the discharge m which case
th ft initial and working pressures remam ap];)n>zimately equal.
GAS ENGINE IGNITION
2,745
1. In connecting up cells the terminals and connecting wires should
be scrupulously clean and bright, using sand paper or a scraper if neo-
essary. All terminal nuts should be screwed down tightly so as to make
a firm connection and reduce the resistance of the joint to a minimnm,
2. Batteries consisting of two or more series connected units should
not be used with series parallel connection except in case of emergency
because the units are never of exactly the same voltage, hence the
storage set tends to discharge through the weaker.
3. Never use more cells than necessary, because an excess of current
will flow, thus reducing the life of the battery.
4. In general four dry cells are sufficient for automobile ignition,
and six for marine ignition.
Figs. 3,942 to 3,945. — Hydraulic anahgy cf
internal reaUtance. Pigs. 3,942 and
3,943 show two tanks <&ells) both having
discharge pipes (external circuits) of prac-
tically no resistance. The internal resist-
ances of the tanks are represented by a
large and small orifice through which the
tanks must discharge. It is evident that
the flow in one case will be high, and in
the other case low, corresponding to initial
currents of celk of low and high internal
resistances. It is certain that on ordinary
work either of these tanks would give
equally good service if the flow requu«d
be less than the initial flow of the high
resistance tank. This is true of dry cells.
The required drain in any kind of work is
less than the lowest initial current; hence,
a low current cell may give just as good
or better service results than a very nigh
current cell.
6MWr ORlFlCt
IU6HinTERnH.R£S)Sm<a
LMIGE ORIFICE.
UQW 1NTERNM.RESIS1>MC£
75 AMPERES
Z5 AMPERES
HIGHIHTERHAI
RES(STAria
ORYoa
5TORM3eC£U.
Fkss. 3,946 and 3,947.—
Columbia R. S. A. sig-
sal cell, type 72. It con-
forms to the R. R. S. A.
specifications for copper
oxide, zinc and soda
primary battery. TTie
cell is self-oiling and does
not require the shipping
or handling of any oil. A
I>totecting layer of oil
automatically forms on
the surface of the solution
within a comparatively
short time after the
element is immersed. A
sand blasted space on jar
is provided lor record.
Although primarily de-
signed for signal work the
cell is also satisfactory
lor gas engine igniton.
Digitized by
2,746
HAWKINS ELECTRK^ITY
5. Weak dry cells can be strengthened by removing the paper jacket
and punching the metal caps full of small hole, then placing in a weak
solution of sal-ammoniac, allowing the cells to absorb all tfiey will take
up. Do this only in emergency; if the holes be closed by soldering, the
cells will last longer.
6. Extra service may be obtained by two run down series connected
units by connecting them in series parallel.
7. Extra service may be obtained oy closer adjustment of the vibra-
tor coil or reducing the distance between the spark plug points.
_j!i05!=*v45Sifflaii_
Pig. 3,048. — Sectional view showing construction of Edison cell. The solution should be
maintained 2^ inches above plates. If solution level be low in any cell, hold battery out
of service until renewal solution can be obtained. Normal charge. After battery
has been practically discharged, the normal charge is for seven hours at normal rate.
Charging resistance should be adjusted from time to time to keep current normal. If
this be mipracticable, set resistance so that current is about 50 per cent, above normal
at the start. It should taper off by rise in battery voltage so that the average current
will be at normal rate. If battery be only half discharged, recharge for half of seven hours
at nonnal rate; if only one quarter discharged, charge for a quarter of seven hours, etc
Low rate charge. To secure best results on five hour or eight hotir dischaxge, charge
at not less than the normal rate. If, however, the cells be discharged at a very low
rate, a charging rate lower than normal can be used with satisfactory results. Ampere
hour meter. An ampere hour meter, if used, should be set to rechaige 25 i)er cent,
in excess of discharge. Discharge rate. The size of cell used shotdd be such that
the continuous discharge does not exceed 25 per cent, above, normal rate. Water, Re-
plenish cells with distilled water as frequently as is necessary to keep solution level above
tops of plate. When adding water do so before charging. Changing solution. After
about every nine or ten months of continuous daily service, test solution with hjrdro-
meter after a full charge. If it read below about 1.160, the solution should be changed.
GAS ENGINE IGNITION 2.747
Secondary Cells. — ^A second chemical means of producing
electricity for ignition is the storage battery which consists of
two or more secondary cells contained in a carrying case or box
usually of wood or hard rubber. A secondary cell is made up of
a positive and a negative set of plate (usually of lead) immersed
in an electrolyte of dilute sulphuric acid. The plates are spaced
apart by insulating separators. The proportion of acid to water
is about one part acid to three and one-half parts water.
In preparing the electrolyte, acid should always be added to
the water — not water to acid.
In passing an electric current through a cell, the plates undergo a
chemical change; when this is complete the cell is said to be charged,
A quantity of electricity has been stored in the cell, hence the name,
storage battery. The cell after being charged will deliver a current in
a reverse direction because dxiring the discharge a reverse chemical action
takes place which causes the plates to resume their original condition.
When fully charged the positive plates are coated with i>eroxide of lead
and are brown in color and the n^ative plates gray.
For a very extended treatment of the subject of storage batteries see
Guide No. 4
Points Relating to Secondary Batteries. — Many storage
batteries are ruined after short service by neglect or ignorance
in caring for them; accordingly, the following items should be
carefully noted.
1. The water in the electrolyte evaporates but the add never does.
2. Keep plates well covered with electrolyte.
3. To replace loss by evaporation add only distilled water, or clean
rain water which has been collected in a non-metallic vessel. The water
must positively be chemically pure or the battery will be ruined within
a short time.
4. The battery capacity is rated in ampere hours. Thus a fifty ampere
hour battery means that with full charge it will give an ampere for
60 hours.
5. Never test a storage battery with an ammeter. The internal resistance
of battery being very low, a very large current flows on short circuit,
hence, an ordinary pocket ammeter would probably be injured — use a
volt meter and take readings while the battery is delivering current, not
when the circuit is open.
6. The capacity of a battery is independent pf its voltage
2J48
HAWKINS ELECTRICITY
7. Don't take it for granted that the wiring on automobile lighting and
starting systems is of large enough size to carry current of a short
circuited storage battery without excessive heating — such short circuit
in the vicinity of a leaking carburetter is not to be recommended
(though only so called "gasoline" be used), especially in the case of
makeshift rigs installed by amateurs.
8. Except for stationary service, keep battery securely fastened in place.
9. Keep battery and interior of battery compartment wiped clean
and dry.
10. Do not permit an open flame near the battery
11. Keep terminals and connections coated with vaseline or grease.
12. Test specific gravity of each cell r^;ularly with a hydrometer.
' 13. When all cells are in good order the gravity will test about the same
(within 25 d^;rees) in all.
Pigs. 3,949 and 3,950. — Circtiit diagrams to illustrate the difference between a dynamo and a
magneto. The former has its field magnets PP magnetized by means of a small current
flowing around a ^unt circuit. In a ma^eto the field magnets are permanently mag^
netized. The strength of the magnetic field of a magneto is constant while that of a
djmamo varies with the output, hence, a magneto mav be run at a widely varying spe^l
and meet ignition requirements, but a dynamo must have its speed maintained approxi-
mately constant to keep the voltage within limits.
14. A dead battery tests 1,150; when fully charged 1,275 to 1,300.
15. A battery which is to stand idle should be fully charged.
16. A battery should not remain idle for more than six montiis without
recharging.
17. Disconnect the leads from an idle battery to avoid any slight leak
in the external circuit.
18. Many batteries are ruined by entrusting their ^re to incompeteni
garage men. Digitized by vjOOg
GAS ENGINE IGNITION
2,749
Mechanical Generators. — ^The two methods of producing a
current by mechanical means are by the use of dynamos or
magnetos.
Ques* How does a dynamo differ from a magneto?
Ans. Chiefly in that the dynamo has field magnets of soft
iron or mild steel, wound with wire through which circulates
the whole, or a portion of the current generated by the machine;
6
Fi& 8,951. — Sectional diagram of the Apple igniting dynamo. The parts shown are: A, cast
iron body containing the moving parts; B, the hinged lid of the body; C. the one pole
piece of one of the field magnets: F, brass bearing of the armature spindle; G and H,
fibre tubes surrotmdin^ the spindle; K, brass spider supporting the spindle; L, conmiu-
tator; M, wick feed oil cup; N, beveled nut supporting the commutator; O, P, Q, sup-
ports of ue commutator; R, the driving disc; S, lever friction pinion. This machine
can generate a direct current at 8 volts at a speed of between 1,000 and 1,200 revolutions
per minute. ^ It is provided with a simple centrifugal governor that automatically inter*
rupts the driving connections when a certain speed has been exceeded.
whereas, a magneto has field magnets constructed of steel and
permanently magnetized, no part of the current adding to the
magnetism.
The circuit diagrams, figs. 3,949 and 3,950, illustrate this difference.
In the dynamo the field magnets FP are magnetized by means of a
small current flowing around a shunt circuit; that is, a certain amount
of current is taken from the system and used to magnetize the field.
The remainder of the current generated is used in the outside circuit*
2,750
HAWKINS ELECTRICITY
Dynamos. — ^The field magnets of a dynamo increase in
strength as the ctirrent which passes around them increases.
Moreover, as the magnetic strength increases, the voltage of
the generated current also becomes stronger. Hence, it is evi-
dent that a d3mamo is not self-regulating, and if run at too high
speed is liable to be overheated or even burned out in its effort
to furnish a current beyond its capabilities, on account of this
faculty of automatically strengthening its own fields.
Pig. 3,952. — Motsinger "Auto Sparker" friction drive dynamo. The small friction pulley
gives sufficient speed to ignite the charge when engine is turned slowly as in cranking.
After the engine is under motion, the governor on the shaft of the dynamo Umitt
its speed so as not to obtain an excessive voltage. This is accomplished by mounting the
dynamo on its base so that it can oscillate on an axis, the small friction wheel making and
breaking contact with the engine fly wheel. In operation, when normal speed ts ex-
ceeded, the governor weights fly out and draw the ^ friction , wheel away from
the fly wheel, one spring serving the double purpose of pushing the friction pulley against
the fly wheel and acting as a tension on the governor. By increasixig or duninishing the
tension on the governor spring by means of a thumb nut provided for the purpose, the
speed of the dynamo may be mcreased or diminished, which in turn increases or dimin-
iwes the volume of current and size of spark. By screwing up on this thumb nut the
position of the dynamo is not changed, but the contact of the pulley and tension of the
governor are incr^ed. Thus, by adjusting the thtunb nut, the size of the spark may
be regulated at wiU.
Ques. Describe the fdction drive for a dynamo.
Ans. In this form of drive, motion is transmitted through a very
small wheel in frictional contact with the fly wheel of the engine.
GAS ENGINE IGNITION
2,751
lO at full speed
This frictional wheel is small enougn to run the dynamo at tull speed
when the engine is turned slowly, as in cranking. As the engine speed
increases, the governor acts, and maintains the speed of the dynamo
Ques. How is a dynamo generally used?
Ans. In connection with a storage battery, the current for
ignition being supplied by the battery, which, in turn, is con-
FlG» 8,053.— Wiring diagram of Remv iflnition, lighting and starting sswtem as installed on
Oaldand automobilM. The 6 volt dynamo is a four i>ole shunt wotmd machine driven
at IH crank meed. A discriminatmg cut out controls its connection with the batteiy
in duuging. The iniition distributer ^Hiich is a part of the dynamo distributes the hifl^
tension current to the cylinders in proper sequence. The interrupter contact points axe
made of silver.
stantly charged by the dynamo to replace the energy drawn
from the battery.
A discriminating cut out or reverse current circuit breaker (erro-
neously called relay) disconnects the dynamo from the battery idien
the voltage of the former becomes equal to, or less than that of thelatter
and this prevents the battery discharging through the dynamo^:^
2,752 HAWKINS ELECTRICITY
Magnetos. — ^There are many types of magneto in use for
ignition. They may be classified,
1. With respect to the armature, as
a. Stationary;
b. Oscillating;
c. Rotating.
2. With respect to the kind of current generated, as
a. Low tension;
6. So called high tension {^JSS^^SS^ coiL
c True high tension. ^ ' ""~ '
FlO. 8,954.— Remy ball bearing shaft skomng inductors and stationary armature of inductor
magneto. This tjrpe of majarneto consists of a winding which i& held stationary between
the pole pieces, on either side of which revolves a laminated steel inductor. Inasmuch
as the wmding is held rigidly stationary, such construction eliminates all revolving or
moving wireS; all sliding or wiping contacts, collector rings, etc. Tliis design permits of
rugged electrical, as well as mechanical, construction. In operation, at each half
turn of the inductor shaft, the direction of flow of the lines of force through the winding
is reversed, producing in the winding two electrical impulses for each complete revolution.
The stationary winding is directly connected through tne magneto circuit breaJcer witii the
primary of the secondary coil used with the magneto. Hie timing of the spark is ac-
complished by shifting the circuit breaker around the inductor shaft, to which is
attached the circuit breaker cam. The timing range is 35 degrees.
Inductor Ma^etos. — In this class of magneto, the arma-
ture is fixed so that it does not revolve and is located with the
sector shaped heads of the core at right angles to the line join-
ing the field poles. This position of the core furnishes the least
magnetically conducting path. An annular space between the
GAS ENGINE IGNITION
2.753
n& 8,0A5 to 8,957. — Double ignition conasting of a two spark high teniion magneto sysfeenL
and a battoy sjmchronous ignition system with engme driven diitribnter. Pig. 8,0U
elementary dianam of connections; fig. 8,956, position of magneto armature Just befoiv
time of ipaxk; fig. 8,957, position of armatuie at time of spark.
2,754
HAWKINS ELECTRICITY
Fig, S,956.— Heinae low tenstoo miigneto. The iieajson round magnets ara used is becanas
it is claimed better contact is thus obtained with the pole pieces or by oairefully grindbis
the ends of the magnets and reaming the holes in pole pieces. Magneiu inatruetionmg
1, Keep interior of breaker box clean; 2, keep phosphor bronze studs on end of armatttro
clean; 3^ keep steel plate in breaker box cleam 4, keep platinum points eiean and
surfaces ffatf 5* use nothing but ento'y paper ot fine file on platinum points; 6, be sure
all leads are solder td in terminals or rigidl-^ coniucled^ 7, platinum pomte shoold be ad-
iusted to .03 of an inch; 8, lubricate: beanng in interrupter le%-er with one drop of very
li^ht oil every two or three tbousaDd miles; 9» Spark plug fiap should be adjusted to a
mmimum of .02 inch and maximum of .025 inch; 10» connect dry cells so as to produce
not more than 3 or 4 vo^ts- 1 1 ^ never leave switch on battery point for any length of time
either when engine is idle or i iuii.u.^% as this causes excessive battery current and will
injure the platinum points; 12, magnetos are considered . running clockwise looking at
the driving end. Sow to efficiently oj^erate a Heinze rnagneto. In the figure the
distributer cover C, and brush arm A, are shown semi- transparent so as to distinguish
parts behind them. Be sure magneto is securely fastened to base and driving shaft is in
perfect alignment. Be sure all connections are soldered or otherwise positively con-
nected. Keep interior of breaker box clean. Keep phosphor bronze studs S dean and
lubricate occasionally with a few drops of very thin oil. Keep inside surface of brush arm
A, dean, as studs S make contact on this. Keep platinum points P. clean and surfaces of
same flat. Use only emery cloth or fine file for uiis purpose. Platinum points should be
adjusted to .02 of an inch separation when open. Gauge furnished on small wrench with .
magneto is proper thickness for this purpose. Adjust by turning platinum point screw'
PI m or out as necessary. Lubricate bearing in make and break lever L. with one drop
of very thin oil every two weeks when magneto is in continuous use. If make and break
lever roll R,^ould becgcne flat from wear, loosen nut N, and turn foil slightly to present
a new suiface to cam, and then tighten again. Be sure leads are rigidly connected in
terminals TT. Leads must be long enough to allow free movement df breaker box.
Remove distributor cover C occasioxudly and wipe out interior of same, sis* clean off any
carbon dust or dirt from distributor brush B. Magneto bearings shoidd be lubricated by
oiling at OOO every week when magneto is in continuous use. Two or three drops are
«noiigh at a time. There is one oiler at rear end which does not show in cut.
GAS ENGINE IGNITION 2,765
armattire and the field poles is provided for the rotation of an
inductor. This consists of two diametrically opposite cylindrical
segments of soft iron supported and carried by a shaft located
at the center of the circle described by the segments.
The magnetic condition of the armature core depends entirely
upon the position of the inductor. The latter is arranged, 1, to
revolve continuously with a gear drive from the engine, or 2, to
rotate to and fro through a small arc by link connection to the
half time shaft.
Low Tension Magnetos. — Generators of this class may be
used to supply a current of low voltage for, 1, make and break
ignition or for, 2, high tension ignition with induction coils or
coil spark plugs. A low tension magneto has an armature wind-
ing consisting of about 150 to 200 turns of fairly thick wire,
covered with a double layer of insulating material.
One end of the winding is grounded to the armature core and the
other, brought to a single insulated tenhinal. When this terminal is
connected to any metal part of the magneto or engine (since the latter
is -n metallic contact with the base of the magneto), the circuit is com-
plete. The wiring therefore is very simple, which is one of the advan-
tages of the system.
The "live end" of the armature winding is brought out by means of
a metallic rod passing lengthways through the shaft of the armature;
a hard rubber bushing is provided as insulation between the shaft and
the rod. The live end of the winding is located at one end of the arma-
ture shaft, from which the current flows to an insulated terminal by
means of a metal contact which is pressed against the revolving rod
by a spring.
High Tension Magnetos. — These are erroneously divided
into three classes, viz : 1, those in which the induction secondary
wiring is wound directly on the armattu-e; 2, those having a
secondary induction coil contained within the magneto, and 3,
those having the coil in a separate box usually placed on the
dash. o
2,756
HAWKINS ELECTRICITY
Pig . 3 ,959 . — Circuit diagram of a magneto with self contained coil . A is the armatiire winding;
P, primary of transformer; S, secondary of transformer; D, distributing brush carrier;
£, contact sefiments; F. safety spark gap; G, terminals to .plugs; U, interrupter; Z,
spark plugs, in operation, altematins current flows from the armature having two
points of maximimi pressure in each armature revolution. As the current leaves the
armature, it is offered two paths: 1, the diorter through the interrupter U to the ground,
and 2, the longer through the primary P of the induction ,coil to the ground. A third path
through the condenser K is only apparently available; it is obstructed bv the refusal of
the condenser to permit the passage of the current, as the condenser will merely ab«oii>
a certain amount of current at the proper moment, that is at the instant of the opening
of the interrupter. The interrupter bemg closed the greater part of the time, allows the
primary current to avail itself of the short path it offers. At the instant at whidi the
greatest current intensity exists in the armature, the interrupter is opened mechanically
80 that the prixnary current has no choice but must take the path through the primary
P of the induction coil. A certain amount of current is at this instant also absorbed bv
the condenser K. This sudden rush of current into the primary P of the induction coiL
induces a high tension current in the secondarv winding S of the coil which has suffideat
pressure to bridge the air gap of the spark plug. The sharper the rush of current into
the primary winding P, the more easily will the necessary intensity of current for a fvanp
spark be induced in the secondary winding S. The distribution of the current in proper
sequence to the various engine cylinders is accomplished as follows: the high tension
current induced in the secondary S of the induction coil is delivered to a distributing brush
carrier D that rotates in the majgneto at half the speed of the crank shaft of the engine.
This brush carrier slides over insulated metal segments £ — ^there being one for each
cylinder. Bach of these segments £ connects with one of the tenninal sockets tiiat are
connected by cable with the spark plugs as shown. At the instant of interrwiption of
the primary current, the distributing brush is in contact with one of the metal segments B
and so completes a circuit to that spark plug connected wilii this segment. Should
the circuit between the terminal G and its spark plug be brok^i, or the resistance oi. the
QMtrk plug be too great to permit a spark to jump, uien the current might rise to an in-
tensity sufficient to destroy the induction coil. To prevent this what is known as a safety
spark gap is introduced. , This will allow the current to rise only to a certain maximunu
tfter which discharges will take place through this gap. In construction the spark di»>
charges over this gap are visible through a snmll glass window conveniently located.
GAS ENGINE IGNITION 2,757
The first mentioned type constitutes the only real high tension
magnetos.
Ques. How does a magneto deliver current to the
cylinders in proper sequence?
Ans. By means of a self-contained distributer.
i
Ques. Describe briefly a so called high tension mag-
neto with self-contained coil.
Fte. 3,960. — Sumter low tension oscillating magneto. In this type the annature does not re-
volve continuously but oscillates back and forth through an angle of about 90*.
Ans. The essential features are a low tension annattire
arranged to revolve in a permanent magnet field and provided
with interrupter, secondary coil, condenser, and distributer.
The construction and operation of this type magneto is clearly
shown in fig. 3,959.
Synchronous Drive for Magnetos. — Ignition magnetos are
generally constructed to deliver an alternating current, that is,
2,758
HAWKINS ELECTRICITY
a current consisting of a succession of regularly alternating
electrical impulses, varying in intensity from a plus maximum
to a negative maximtim, and separated by points of zero pres-
sure depending upon the armature position with respect to the
field.
Hence] it is necessary that the generator, unless geared to run at hip^
speed, should be driven synchronously, that is, at a speed in a definite
rate to that of the eng[ine, in order that the periods when a spark is
desired shall coincide with the periods when sufficient voltage is being
developed, as otherwise the sparking periods might occur with a zero
point of electrical generation, and no spark would be produced.
RIOHT.
BRjS. 3,961 and 3,962. — Sumter low tension magneto installed on stationary engine, and triftrlrtf^
on the ends of shaft and bearing for timing. To time^ turn engine over in running direction
until igniter snaps; be careful not to turn past this point. With gear on ma^eto shaft,
turn the magneto in running direction until timing mark N on the shaft is m line with
mark L, if rotation be left hand, or R, if rotation be right hand. Now mesh the gears,
without moinng the timing; this is accomplished by a proper location of the keyway in
the magneto gear in relation to a marked tooth on same. The teeth on the engine drivins
gear meshing with marked tooth on magneto gear should also be marked, and after thia
marking is once determined all keyways may be cut in proper relation to the marked tooth,
tihus making all magnetos on the same type of engine interchangeable. These "'^^ gn ptoe
are usually driven at engine speed, but may be driven at other speeds.
To meet these conditions, the drive must be positive and may
consist of either toothed wheel gears or chain and sprocket; the former ti
more desirable, since, with a daain and sprocket drive, there is sufficient
GAS ENGIltB IGNITION
2,759
Pigs. 3,963 to 3,965. — ^Timing Sumter low tenskm magnetos. Type "Imp" is timed as in
figs. 3,963 and 3.964, the end of shaft and bearings being marked as m fig. 3,965. All
other Sumter magnetos are timed as shown in figs. 3,963 or 3,964. Some machines have
the notched disc as per fig. 3t9^3: others, the pointed disc, fig. 3,964. In either case, the
timing is exactly the same. With the pointed disc, use the point to time with instead of
the notch. Speed f On single cylinder 2 and 4 cycle engines, magne-;os may be run at
engine speed, or IJ^, IH. l?i. or twice engine speed. In the majority of cases, engine
speed is mo^t desirable, although other speeds result in reversing the current through
igniter pomts, preventing pitting, which is advantageous. On two ana four cylinder,
4 cycle engines, run magneto at engine speed. Three cylindel"s, at 1 H times engine speed.
For fixed ignition, turn the engine in the direction in which it runs until the igniter snaps.
Do not turn past this point. Observe the setting disc on the magneto shaft, and so mesh
the magneto driving gear with gear on engine that either small notch N (see cut) is exactly
in line with the mark R on the end plate if rotation be right hand, or L, if rotation be left
hand, looking at magneto from gear end. Where timing discs have points like fig. 3,964
set either pomt in line with the proper mark. For variable ignition, where the range is
not excessive, place the spark lever in the starting position, and then time the magneto
as described above. Some engine builders prefer to reverse this order, giving the best
spark for the advance or running position, although for starting on magneto it is preferable
in most cases to use the best spark for starting. These are matters which have to be
tested out by the manufacturer, and the engine dealer and user should be particular not
to change the speed or method of timing on the engine as originally furnished. When
magneto is properly timed, it is necessary to secure the magneto gear against slipping.
The gear should be marked and keyway cut to register with keyway in armature Mart.
As the keyway is the same in all armature shafts, the gears may also be keyed and marked
alike, and by simply meshing the marked tooth on magneto gear with marked tooth on
driving gear, the correct timing will be obtained without the necessity of setting each
magneto. The driving gear should be so meshed that there is a very small amoxmt of
play. Otherwise, destructive wear of magneto bearings will take place. The amount of
play is sometimes provided for by the engine manufacturer, by adjusting collars in the
magneto bracket, or is easily accomplished by shimming either the magneto itself or the
bracket. In old engines, when checking timing, it is best to note that the magneto marks
line up when the piston is in the proper firing position, as it is possible that the igniter
may have gotten out of time with the piston through wear. If so, the igniter should be
properly adjusted, so that it will snap in time with the magneto. Sometimes the magneto
IS suspected of being out of time, when as a matter of fact it is the igniter. Igniters should
be so adjusted that the points* remain closed as much as possible, and open only to make a
spark. This not only keeps the points from getting cfirty, but also gives the magneto
time to "build up" and produce its maximum current.
NOTE. — Sumter reversing attachment. Many marine engines are reversed "on the
spark,** and to accomplish this, a special attachment is necessary. This consists of a collar on
magneto shaft carrying the gear and having a pin engaging a cutaway shoulder on the collar.
This arrangement allows sufficient lost motion between the gear and collar so that, when the
engine is reversed, the magneto is brought in time with the snapping of the igniter.
2,760 HAWKINS ELECTRICITY
^ lost motion when the chain is loose enough for smooth running
to prevent the accurate timing of the spark.
The friction gear drive or belt and puUey are alike objectionable,
fifom the fact that no slipping or variation is pennissible. While some
recent forms of high tension magneto are advertised to operate asyn-
chronously, that is, not speed^ in definite ratio to the engine, Hie
common tjrpes are sd made that the spark shall occur in the cylinder
at precisely the moment the magneto armature is at a certain point in
its rotation. If, therefore, this condition be not strictly observed, the
spark will be of defective intensity.
Pig. 3,066. — Sumter electrode for make and break ignition. In eonstruetion, the stem is
iimilated with rolled mica, which does not have any upturned edges in the combustion
chamber. The taper arrangement makes it imi>ossible to loosen or pull out the insulation.
A copper gasket mside the igniter casting makes a gas tight joint. The stem is Umg
enough to take care of igniter castings of various thickness, and the superfluous portion
may be cut off.
Ignition Systems. — ^There are two systems in general use
for igniting the charge by electricity:
1. The low tension or make and break,
2. The high tension or jump spark,
Ques. What are the characteristic features of each
system?
Ans. The low tension system is electrically simple and me-
chanically complex, while the high tension system is electrically
complicated and mechanically simple. Digitized by Goog
GAS ENGINE IGNITION
2,7ftl
Low Tension Ignition. — In this system there is a device
known as an igniter, placed in the combustion space of the
engine cylinder. This consists of two electrodes, one of which
IS stationery and the other movable. The stationary electrode
is instdated, while the other, having an arm within the cylinder
and placed conveniently near, is capable of being moved from
the outside so that the arm comes into contact with the station-
ary electrode and separates from the latter with great rapidity.
Pigs. 3,967 to 3,070. — Bosch magnetic spark plug. This consists of a coil A having one end con-
nected to a terminal B , and the other to the pltig casing C. A spark is produced when a sepa-
ration takes place between the moving contact D and the stationary contact £. Within
the plug is a metal core P and a swinging lever G, which lever pivots on the projection
H which is a part of the core P. K shows a portion of a hair-pin spring, the end E of which
rests in a recess within the lever^ G, the ordinary tension of the spnng tending to hold
the lower end of the lever G carrying the contact u against the stationary contact piece £•
This sudden breaking of the circuit produces an electric arc or
primary spark caused by the inductance — ^that is, by the "iner-
tia" or tendency of the current to continue flowing after the
separation of the contact points.
The current may be derived from either a primary battery,
storage battery, or low tension magneto. . ^
2,762
HAWKINS ELECTRICITY
Ques. Name the elements in a low tension circuit.
Ans. 1, a source of current supply consisting of either a
primary battery, storage battery, or low tension magneto, 2, a
primary induction coil when a battery is used, 3, an igniter.
ri^%
>OVANCC
SATTEf^Y
®
Fig. 3,971. — ^Low tension or make and break system. Two sources of eurrent supply are
provided: a drv battery and a magneto. One terminal of both the battery and magneto
18 grotmded^ the other terminal A, of the magneto M, is connected to ^e ^oint S, of a
two way switch. The cells comprising the battery J. are connected in series and the
terminal not groimded is connected to a primary induction coil K, and thence to the
point T of the two way switch. By moving the arm of this switch to the riffht or left,
current may be had from the battery or magneto respectively. A conductor C, connects
the third point of the switch to the stationaiy or insulated electrode of each igniter, a
single throw switch beinfi[ placed at each igniter which allows either or both cylinders
to be thrown out of the circuit at will. The movable electrodes and metal of the engine
furnishes the ground return to the battery and magneto. On a multi-cylinder engin^ it
is evident that no other contact can be made at the moment of break in one cylinder
since the current would then flow through any other igniter that might be in contact
instead of producing a spark at the break. The operation of the make and break system
is as follows: Starting, say on the battery ^ the arm of the two way switdi is turned upon
point T. The movable electrode D, of the first cylinder being in contact with the insulated
electrode B,by the spring E, the current will flow from the battery J through the coil iC,
thence through the two way^switch and the single throw switch to the insulated electrode
B. The movable electrode!), being in contact with the insulated electrode B, the current
returns to the battery through D and the metal of the engine, thus completing the circuit.
As the cam G revolves in the direction indicated by the arrow, its nose passes ixoita
tinder the lower end of P, the latter drops with great rapidity by the action of spring H
and in so doing a shoulder at the upper end of P, struces the external arm of D a blow
causing; the contact point of D to be quickly snapped apart from B, producing an
arc which ignites the charge. This cycle of operations is repeated by the igmtioQ
mnchanism of each cylinder in rotation.
GAS ENGINE IGNITION
2,763
4, a switch for breaking the circuit, and an additional switch
to alternate between the battery and the magneto when both
means of furnishing the current are provided, and 6, connecting
wires, as shown in fig. 3,971.
Ques. How is the spark produced in the low tension
system?
Ans. The sudden breaking of the circuit by the quick sepa-
ration of the electrodes produces an dectric arc or primary
Fks.
3.972. — ^Wiring diagram of a low teosion system with magnetic spark plugs. A portion
ot the wiring of the magneto armature is short circuited by the platintun points of the
interrupter, and when the circuit is broken the resulting armature reaction has the effect
of raising the armattire voltage sufficiently to operate the plugs.
Spark caused by the inductance — ^that is, by the **inertia*' or
tendency of the current to continue flowing after the separation
of the contact points.
Ques. What is the object of the primary induction
coil?
Ans. To intensify the spark.
When a magneto is used, a coil is not necessary, as the armature
winding serves the same purpose. A magneto furnishing either direct
2,764
HAWKINS ELECTRICITY
or alternating current may be used; the voltage will depend on the
armature speed and the strength of the magnets.
Ques. What is used for the electrode contact pohits?
Ans. Iridium or platinum, as these metals resist the oxi-
dizing effect of electricity and heat better than others.
Ques. What is the action of
the current in low tension
ignition?
Ans. A considerable interval of
time is required for the current to
rise to its full value, and the time
of separation of the electrodes should
not be sooner than the moment when
the maximum current strength has
been attained. When a magneto
FlG» 3,973. — Bosch low tension, type NO, oscillating
magneto used in connection with mechanical make
and break igniters. A cturent wave being produced
by each oscillation of the armature, it is necessary
to drive the magneto in a fixed relation to the
engine crank shaft. The magneto trip lever should
be mechanically connected to the movable igniter
on the engine, as in this way only can proper
synchronism be obtained. It should be borne in mind, however, that the
type *'NO" cannot be tised at speeds greater than 250 ignitions per
mmute,and where a greater speed is desired, the type *'KR 'which has a
rotating armature, should be used. In timing the rnaffneto, the mark on
the armature should register with the proper mark on the dust cover, thug
making the timing for either rotation extremely simple, in that it re<jiiire3
no disassembling of the instrument. Since no method i>f varying the timiog
of the spark is provided, arrangements to this end shnu!;^ he made in the
tripping mechanism, and since the igniter and the arTniuut! itvn driven in
synchronism by the trip lever, the instnunent is always operated at its point
m maximum efficiency regardless of whether the spark be retardedTor advanced. In
order to obtain proper results, the trip lever should be deflected through an angle of 30
degrees before it is released, and, since the spark is produced by spring action rauier than
duectly through the speed of the engine and therefore is index>endent of the latter, no
battery is necessary for starting, and in ordinary cases one turn of the fly wheel wiU be
sufficient, provided, of course, that a proper gas mixture be present.
is used, the current strength increases with the speed, hence
the contact interval can be shorter at high speeds than when
a battery is used. .
GAS ENGINE IGNITION
2,766
Ques. In low tension ignition, wliat is necessary in
order to produce a good spark?
Ans. Thie **5reafc" or separation of the contact points of the
igniter should take place with extreme rapidity, that is, the
spring H (fig. 3,971) should be sufficiently strong to cause the
shoulder or rod F, when it falls, to strike the igniter arm a
decided blow, thus quickly snapping apart the contact points.
FxGS. 3,974 and 3,975. — ^Low tension ignition system with inductor magneto. Pig. 3,974,
position immediately before sparking; fig. 3,975, position immediately after q;>arking.
In coitatruetion, vie cam wnich operates the make and break i^ter has a hnk conr
nection to the inductor crank of the magneto which gives an oscillating motion to the
inductor. The connection is such that at &e instant of break" the inductor cuts throus^
the greatest number of magnetic line. In offeration, the cam C» on the half time shaft,
makes a contact just before sparking, and immediately breaks it again by permitting
the hanmier T to fall on the cam S. A spark is produced at the instant of break of contact
at N. The winding of the armature A has one end grounded through the base of the
magneto^ the current returning through the engine to the point S( the other end of the
winding is led through an insulated post to the nut N by which it is connected with a
stud brought through the cylinder wall, where a wiper, indicated by dotted outline, nor-
mally rests against it by means of a spring.
Ques* State some disadvantages of low tension ignition.
2,766
HAWKINS ELECTRICITY
Ans. Mechanical complication, excessive noise, wear of the
igniter i)oints, and i)ossible leakage through the igniter.
Ques. For what service is low tension ignition espe-
didly suited?
Ans. For marine service especially in open, off shore fishing
boats, such as Cape Cod dories, Sea Bright skiffs, etc.
Pig. 3.-076. — Hammer break igniter. It consUtB of two metallic terminals A and B. The
texminal A is mounted on a movable shaft C, while B is stationary and in9idated from the
cyhndei wall by the lava bushing D. A suitable cam rod, attadbed to the crank E, pro-
vides the means for rocking the terminal A, so as to bring it in contact with the terminal B«
and then quickhf separale the terminals to produce the spark. The helical spring P.
provides a seminexible connection between the shaft C, and the crank B. The contact
points of the two terminals are tipped with two small pieces of platinum G and H, and both
terminals are mounted in the removable plug K, wnich is usually inserted throu^ the
wall of the cylinder head, so that the igniter points extend into the compression space
of the cylinder. In the circuit is a battery L, and primarjr spark coil M. In operation,
when the igniter terminals are brought together, the circuit is closed through the battoy
and the spark ocil, and when the terminals are quickly separated, the self inductioo
of the coil causes an elfectric arc between the igmter terminals which igmtes the diaxge.
GAS ENGINE IGNITION
2,767
Ignition with Inductor Magneto. — In this system of low
tension ignition, the current is furnished by a magneto having a
stationary armature and a rotating inductor as before described.
The inductor is arranged to either revolve continuotisly or to oscillate
through a small ara An example of the latter type for low tension
^tion is shown in figs. 3,974 and 3,975 which illustrates the Simms-
Bosch system.
FttS. 8,977. — Wipe contact igniter. It conaista of two independent electrodes, the stationaxy
^ectrode A, and the movable electrode B. The igniter is located in the inlet chamber
G, directly over the head of the admission valve H, and either one of the electrodes can
be reached for inspection or removal independently by removing the cap K. In operation,
when B is revolved by the motion of the igniter rod C, the revolving blade D, is brought
mto contact with the spring E, at each rotation and produces the spark. A feature of
this tjrpe of igniter is that the wiping contact prevents the accumulation of burnt carbon
on the contact surfaces and this serves to reduce the resistance of the closed circtiit.
It ia aubject however to wear of the contact surface, and breakage of the sprix^.
In adjuatina the, timing can be changed during operation by turning thumb screw P«
on the end of the igniter rod, advancing or retaroing the arc.
Low Tension or Make and Break Igniters.— These devices
may be divided into two general types according to the manner
2,768 HAWKINS ELECTRICITY
of separating the terminals, that is tc say, according to the method
of break, as hammer break, and wipe contact (figs.3,976 and 3,977.)
High Tension Ignition* — ^In this method of producing a
spark, a device called a spark plug is employed. It consists
of two stationary electrodes, one of which is grotmded to the
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ffns. 3,078 and 3,979. — ^Eisemann type G4 magneto showing method of timing and special
wrench. Timing ihe magneto: As the spark occurs when the primary circuit is broken
by the oi>ening of the platinum contacts in the make and break mechanism, it is necessary
that the magneto will be so timed that at full retard position of the timing lever body, the
platinum contacts will open when ^e respective piston of the enme has reached the top
point on the firing stroke. Turn engine by hand until piston of No. 1 cylinder is on the
upper dead center: remove distributer plate from magneto and turn ^e driving axle of
the armature tmtil the setting mark on the distributer disc is in line with the setting
screw as shown. (For clockwise rotation use mark R, for counter clockwise, use mark L).
With the armature in this position, the platintmi contacts are just opening, and the metal
insert of the distributer disc is in connection with carbon for No. 1 cylinder. The driving
medium must now be fixed to the armature axle without disturbing the position of the
latter, and the cables connected to the spark plugs.
NOTE. — Primary Induction Coila. ^ When an electric current flows alon^ a coiled
conductor, an inductive effect is produced which opposes any rapid change in the current strength.
This principle is employed in low tension ignition to intensify the spark when a battery forma
the current source. The device which accomplishes this effect is known as a primary induction
coil and consists of a long iron core wound with a considerable length of low resistance copper
wire, the length of the core and the number of turns of the insulatal winding determining the
efficiency. The current passing through^ the winding magnetizes the soft iron, and a self-
induced current is generated. When the circuit is broken, the magnetic reactance tends to con-
tinue the flow of current, despite the break in the circuit, and occasions a spark of great heat ^^A
brilliancy. The spark occurs at the nument qf breaking the circuit, not at the moment qf making^
GAS ENGINE IGNITION
2,769^
engine cylinder and the other insulated. The points of the
electrodes are permanently separated from each other by about
^ of an inch, the space between the points being known as
an air gap. This space offers so much resistance to the flow of
an electric current that a very high pressure is required to cause
the current to burst through the air gap and produce a spark,
hence the term "high tension ignition," meaning high pressure
ignition.
Since the spark jumps from one electrode to the other, this
method of igniting the charge is also known as the jump spark
CN&»NE. CYLIHDE.RS
Ste. 8,980.— Wiring diagram for K-W type
H and HT magneto, for firing order
1. 2, 4, 3. To time magneto: Place
No. 1 piston on upper dead center of
compression stroke, and have rocker
arm A, horizontal as shown. Shift
magneto around until distributer brush
B, touches segment S, thus connecting with cylinder No. 1.
^ift magneto slowly by hand, in the proper direction of
rotation, until the contacts P are just beginning to separate. rl AfiN ETO
At this point secure magneto shaft to gear or coupling with set screws. When one cylinder
is timed, proceed to connect the others as follows: Ascertain the firing order of the engine,
^en crank ennne slowly and connect plug cable from next cylinder that fires to distributer
segment No. 2 and so on until all the plug cables are connected. The secondary con-
nections on the hard rubber distributer block are numbered in consecutive order, 1, 2, 8^ 4«
etc. These numbers do not refer to the engine cylinders, and it is necessary to determine
the order in which the cylinders fire and connect secondary cables accordingly. Replace
parts on the magneto and start the engine to test the setting. See that all nuts and
connections are tight, also that retainer spring has been replaced. There ^ould be a
tendency for the engine to kick back slightly when starting, and if it do not, advance
magneto until it does kick slightly. To advance, shift coupling against direction of
rotation. To retard, shift coupling with direction of rotation, ^ift slightly each time
until correct position is obtained. Fin magneto shaft to gear or coupling with taper paw
do not depend on a set screw, as it will suiuy work loose in time. ^^
2,770
HAWKINS ELECTRICITY
system. The spark itself is properly described by the prefix
high tension or secondary.
In the production of the spark two distinct circuits are necessary; 1, a
low tension or primary circuit and 2, a high tension or secondary circuit.
The current which flows through the low tension drctiit is called the
primary current and that which it induces in the high tension circuit,
the secondary current.
In order to obtain the high pressure required to produce a spark, a
device known as a secondary induction coil is used which transforms the
primary current of low voltage and high amperage into a secondary
current of high voltage and low amperage, that is, the xjuantity of the
current is decreased and its pressure increased.
The general principles upon which high tension or jump spark ignition
is based are as follows:
An automatic device is placed in the primary circuit which closes
and oi)ens it at the time a spark is required. When the circuit is closed,
the primary current flows through the primary winding of the coil and
Pig. 3,981. — ^Automatic spark advance mechanism and armature of Eisemann ma^eto. The
automatic advance is accomplished by the action of centrifugal force on a pau- of weight
attached at one end to a sleeve through which runs the shaft of the magneto, and hinged
at the other end of the armature. Along the armature shaft, run two hdicoidal ridges
which engage with similarly shaped splines in the sleeve. Jn operation, the rotation of
the armature causes the weights to spread and exert a longitudinal pull on the ^eeve
which in turn changes the position of the armature with reference t9 the pole piTO«i.
Thus, the moment of greatest induction is advanced qr retarded and with it the break in
the primary circuit, for the segments (or cams) which left the circuit breaker and cause
the break in the primary circuit are fixed in the correct position and thus the break occutb
only at the moment when the current in the winding is strongest. On other magnetos
it is the segments or cams that are moved forward or back as the case may be. To apply
the automatic control principle to any engine, there have been produced spindles of
varying pitches; spindles that will give 19. 25. 38. 45 and 60 degrees aivMice. For use
in connection with these spindles, there are sixteen different springs. With tiiese i)arts.
in connection with the governor mechanism, 160 advance curves can be produced. By
varying the length of the stop on the bronze nut, more may be obtamed. Many engines
require a great deal of advance, others will not permit of more than 20 to 25 dtt^rees. it is
necessary to take into consideration the size and shape of the combustion chamber, the
compression, the position of the spark plugs and the speed of , the motor. It is also univers-
ally acknowledged that an engine of high compression will give a quicker burning mixture
and will not require, or in some cases, stand, as early a spark as one of lower compreesLoo.
GAS ENGINE IGNITION
2,771
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Horizontal Coll Type ^^C^
ViGS. 3,982 and 3,983. — ^Boech type C horizontal secondary coil, in eonatruettorig a movable
brass cover 2 carries the switch handle 1, and is attached to the cylindrical coil housing 3
bv means d a bayonet joint. The press button used for starting projects from the center
of the cover. ^ A pin set on the cod end plate engages an opening in the cover, which
causes the coil and cover to move together. The switch contacts being located on the
other end plate of the coil, this permits the operation of the switch by the movement of
the cover. Switch poaitiona: Pour positions are provided, 1, O, off, 2, B, battery.
3, MB, magneto and battery, 4, M, magneto. The base of the coil housing is formed
by the stationary switch plate 6, and the contacts carried on it register with the contacts
of the movable switch plate 7. The partial rotation of the coil by the movement of the
cover plate causes the different switdi contacts to engage. The coil body consists of a
cylindrical iron core 10, upon which are wound the primary and secondary winding;
tne former consists of a few layers of heavy wire, and the latter of many layers of fine wire.
One end of the primary winding is connected to a segment on switch plate 7, while the
other end leads to the vibrator, from whence it passes to ground. The iron core 10, carries
the condenser 12, and to it is screwed the end plate 11 that supports the starting device.
The parts of the starting device are the brass button 4, the contact spring 13, cmd the
vibrator blade 14. When the switch handle is turned to either of the battery positions,
a pressure on button 4, will complete the primary circuit by causing the contact pin to
touch the platinum point carried on spring 13. This contact will be in parallel with the
primary timer, and ttie current will flow from the blade 14, to the end plate 11, to the iron
core 10, and by binding post 9, to grotmd. Lock: The coil is provided with a key lock,
which may be operated only when the coil is in the "Off" position. This prevents the
unauthorized use of the engme, and by making it impossible to lock the switch in any of
the operative positions, renders unlikely that the switch will be left unintentionally on
one of the battery positions to the injury of the battery. Battery voltage: The coils
are wound for a current of six volts, and a six volt, sixty ampere hour storage battery is
recommended. If it be necessary to use dry cells, ten should he provided for a 4 cylinder
syst^n, and twelve for 6 cylinders, connected in series parallel. They should be divided
into two groups of five or six cells each; the cells of each group should be connected in
series, and the groujM connected together in parallel. ^ <^
2,772
HAWKINS ELECTRicrry
causes a secondaiy current to be induced in the secondary winding.
The spark plug bemg included in the secondary circuit opposes the flow
of tiie current Dy tie high resistance of its air gap. Since the pressure
of the secondary current is sufficient to overcome this resistance, it
flows or ''jumps]^' across the gap and in so doing, intense heat is pro-
duced resulting in a spark.
Sometimes the spark is obtained by keeping the primary circuit
closed except during the brief interval necessary for the passage of the
spark at the plug points. A secondary spark, then, may be produced
by either open or closed circuit working, that is, the primary circuit
may be kept either opened or closed during the intervals between sparks.
Fig. 3,984. — Diagram of a secondary, vibrator tyi>e induction coil. TheparU are a& foUowtf
A, contact screw; B, battery; C, core; D, vibrator terminal; G, condenser; P, primary
windinc[; S, secondary winding; W. switch; Y, vibrator, in operation, when the
switch is closed, the following cvcle of action takes place: a, the primary current ficws
and magnetites core; b, magnetized core attracts the vibrator and breaks primary circuit; e, the
magnetism vanishes^ inducing a momentary high tension current in the secondary winding,
producing a spark at the air gap; d, magnetic attraction of the core hating ceased, vibrator
spring re-establishes contact; e, primary circuit is again completed and the cycle begins anew.
The automatic device which controls the primary current to produce
a spark by the first method is called a contact maker, and by the second
method, a contact breaker, A closed primary circuit with a contact
breaker is used to advantage on small engines run at very l^h speed
as it allows time for the m^netism or magnetic flux in the core of the
coil to attain a density suflScient to produce a good spark The word
Hmer is usually applied to any device which controls tie primary current,
when it controls both the primarjr and secondly currents* as in syn^
chronous ignition, it is callea a distributer. Before explaining tiie different
^tems of high tension ignition the several devices used, such as in-
auction coils, spark plugs, etc, will be described in some detaiL
GAS ENGINE IGNITION 2,773
Among the various devices used in high tension ignition the
following are of importance and the function and construction
of each should be clearly understood.
Secondary Induction Coils. — In order to obtain the high voltage
necessary to produce a secondary (jump) spark, a secondary induction
coil is used: it is a species of transformer and transforms the primary
low tension current into a secondary high tension current. It consists
essentially of four main parts: 1, an iron core; 2, primary winding,
3, secondary winding, and 4, condenser.
Pig. 3,985. — Contact maker and mechanical vibrator. The case. A, is usually attached to
the sear box of the engine; B, is the vibrator blade; C, a platinum contact point; D, an
insulated adjusting screw; £, a bushing with insulation; P, the operating cam. As
this cam revolves the weight on the end of blade, B, drops into the rece&3 on the cam
causing the blade to vibrate and make a number of contacts with D, thus producing a
series of sparks when in operation.
Timers. — ^These devices are simply revolving switches operated by
the engine and so adjusted that the primary drctiit is made and broken
in proper sequence with the . iigine cycle, so that the spark may occur
at the proper point with respect to the crank position. A timer is geared
to revolve at one half engine speed for a four cycle engine, and at engine
speed for a two cycle engine. The distinction between timers and dis-
tributers should be carefully noted, to avoid the usual erroneous use of
these terms.
Special Forms of Timer, — In order to meet certain conditions of
operation, special timer construction is sometimes used, giving rise to
types of timer which are known as:
1. Contact makers;
2. Mechanical vibrators, or tremblers;
3. Contact breakers; r"^r^^]r>
4. Interrupters. Digitized by v^OOglC
2,774 HAWKINS ELECTRICITY
A contact maker keeps the circuit closed for only a short interval,
whereas, a contact breaker keeps the circuit open for only a short intervaL
A contact breaker is intended to meet the conditions of extreme high
speed, that is, by keeping the primary circuit closed ezc^t during the
bric^ interval necessary for the passage of the spark, sufficient time is
fiven for the magnetic flux of the core of the magnet to attain a suffident
ensity to induce a secondary current of the required strength.
An mtemipter is virtually a contact maker located on a magneto and
forming a part of the latter machine.
Distributers. — ^When one secondary; coil only is used with a muhi.
cylinder engine as in synchronous ignition, a device called a distributer
is a necessary part of the system. Its use is to direct the discharge of
a single coil to the spark plug of each cylinder in rotation. A distributer
Pro. 8.086.— Contact breaker. Thia device keeps the drcmt cloaed at all times except durinc
the brief interval necessary for the passage of the spark at the ^lug points. It is used to
advantage on engines running at very hic^ apeeds, as it allows time for the magnetic nnz
in the core of the coil to attam a density sufficient to produce a good spark.
consists of a timer for the primary current, and a similar device for the
secondary current working sjnichronously, that is, in step with the timer
and which switches the secondary current to the various spark plugs
in the proper order of firing.
In other words, a distributer is a combination of two timing devices
working in unison with each other; one makes and breaks the primary
NOTB. — The primary element of a distributer contains as many stationary con-
tacts as there are cylinders and a revolving arm or rotor which in its revolution touches each
of the stationary contact so that the primary circuit is made and broken once for each cylinder
during one revolution of the arm. The eecondary element is above and concentric with
the primary part. It has a rotor and the same number of stationary contact as the primary
element; the parts of both elements are arranged symmetrically with each other and are
contained in a compact cylindrical casing. A shaft geared to the engine operates both the
primary and secondary rotors. The primary rotor is in metallic contact with the shaft and
terms with it and the engine a ground return for the primary circuit. The secondary xotor it
carefully insulated. All the primary stationary contacts are connected to one common teiw
minal which receives the primary lead. A binding post is provided for rach of the secoadnry
«tationary contacts and one for the secondary rotor. These binding posts are usually placed
con the top part of the casing. - o
GAS ENGINE IGNITION
2,775
drcuit, while the other makes and breaks the secondary circuit and in so
doing distributes the current to the several cylinders in correct sequence.
SiMurk Plugs* — In all high tension ignition systems a permanent air
gap is placed in the secondary circuit across which the current must
]umi> to produce a spark. The device by which this permanent air
gap is maintained is called a spark plug. There are several varieties
Pic. 3,987. — Sectional view of the Pittsfidd distributer. In this device several revolving
contacts are employed instead of one; these consist of a double spring making sliding
contact at the portions, A. The parts are: 1, contact springs; 2, shaft; 3, bushing;
mfig. S
E, secondary cable. .The principles of distributer operations are plainly shown
of spark plug, of which the following are extensively used: 1, primary,
or ma|^etic make and break plugs, 2, secondary, or jump spark plugs,
indudmg plain and special forms such as coil plugs.
2,776
HAWKINS ELECTRICITY
Various High Tension Ignition Systems. — ^There axe a
number of satisfactory method for producing a secondary or
high tension spark, such as ingition
1. With plain coils;
2. With vibrator coils;
3. With master vibrator;
4. With single coil (synchronous ignition);
Figs. 3.988 to 3.994.— Sections of well knows spark plugs. Tbe first five have pocodaifl
insulation; the last two, mica.
5. With dynamo and storage battery;
6. With magneto:
7. With special igniting devices.
NOTE. — Sparking presBurc. A current of veiy high voltage is required to produce a
secondary or iump spark on account of the great resistance of the air gap and compression
pressure which oppose the current flow. The required voltage will depend on the length of
the air gap and .the intensity of the pressure inside the cylinder. For ordinary spark plugs
in air the sparking pressure will varj^ from about 3,000 to 5.000 volts accordizu^ to the length
of the gap, but to produce a spark in an engine cylinder where the mixture has been com-
pressed to four or five times the atmospheric pressure, will require from 10,000 to 20,000 volts.
When a apark plug will not work* the electrodes and insulating material should be thor-
oughly cleaned with fine sandpaper and the distance between the points adjusted to about
one thirty-second of an inch, or the thickness of a ten cent silver piece. If the battery be weak^
the gap may be made smaller.
GAS ENGINE IGNITION
2,777
Ignition with Plain Coils.— The first high tension system
to attain popidarity was the single spark sjrstem using a plain
coil and contact maker. This being the simplest method of
producing a secondary spark, it will serve to illustrate the
several principles involved in jump spark or high tension igni-
tion, as explained in fig. 3,995.
COMNEGTIOH
Pig. 3,995.— Diagram illtistrating the principles of hifi^ tension or jump spark ignition. The
nose ot the cam in revolving engages the contact maker which completes the primary
circuit and allows current to flow from the battery through the primary winding of the
coil; this magnetises the core. The primary circuit is now broken by the action of the
cam and magnetic changes take place in the coil which induce a momentary high tension
current in the secondary circuit. The ^reat pressure of this current forces it across the
air gap of the spark plug and as it bridges the gap a spark is produced. The arrows
indicate the paths of the currents. At break, the primary current is "slowed down" by
the condenser, thus preventing an arc between contact breaker contacts.
Ignition with Meclianical Vibrators. — ^The view held by
some that a series of spark closely following each other is more
effective for ignition than a single spark, led first to the intro-
duction of the mechanical vibrator. This system employs a
plain coil and is identical with the one just described with the
2,778
HAWKINS ELECTRICITY
exception that in place of the make or break timing device, a
mechanical vibrator is used which gives a succession of spark
for firing each charge.
As the rotor of the timer revolves, it touches each of the stationary
contact and in so doing, the above cyde is repeated for each cylinder in
the order of firing, as wired.
Ignition witli Vibrator Coils.— A more refined method of
producing a series of spark for igniting the charge is by the
FKI. 8,096. — Wiritig diamm. of a dual jump spark syatem for a four cylinder, four cjrcle e_
A dry battery analow tension magneto form the two sources of current supply,
primary, or low tension circuit is ^own by heavy lines, the secondary or hini tension
circuit by fine lines, and the leads to spark plugs by the double lines. The dotted rectaoffle
l epre s ents the outline of a four unit dash coiL in the coil connection* it ahould be noted
that the adjustable contact screw of each vibrator is connected by a common wire ter-
minating at the two way switch; ,also, in each unit one end of the secondary winding is
connected to that end of the primary, leading to the vibrator blade. These common
connections simplify the external wiring, as otherwise there would be four binding posts
tor each unit. The two way switch just referred to permits the ctirrent supply to be
taken from either of two sources, such as a battery and a magneto. Current is supplied
by the battery when the switch is in the position shown in the figure. By turning the switch
to the right, a current from the magneto will be furnished. With the battery in the
circuit and the timer in the position d^own, the Operation im a» foliowa: Current flows
from the positive terminal of the battery, to the switch, thence, to the contact screw of
coil number two. Prom here, it flows through the vibrator blade, primary winding of the
coil timer and the metal of the en^e, and returns to the battery. The primary drcoit '
is alternately opened and closed with great rapidity by the vibrator so long as uie rotor
of the timer is m contact with terminal 2. During this interval, a series en hu^h tension
current is induced in the secondary circuil producing a series of spark. The current
which flows through the secondary wmding is in a direction opposite to that of the primary
current. At each interruption of the primary current, an mduced high tension current
flows through the secondary winding, to the spark plug, across the gap. producing a spark
and returns through the metal of the engine, timer, and back to the coil, o
CAS ENGINE IGNITION 2,779
use of a vibrator coil. The magnetic vibrator is a marked im-
provement on the mechanically operated device as it vibrates
with greater rapidity and is capable of delicate adjtistment.
This system which is extensively used is illustrated in fig. 3,996,
which is a wiring diagram for a four cylinder engine.
Ignition with a Master Vibrator. — In a multi-unit coil
there is a vibrator for each unit, all of which may be operated
by a single or master vibrator. The advantage of such a system
Fig. 3,097. — Circuit diagram of a master vibrator coil. B, is the battery; C, the unit coils;
CI, C2, etc., the condensers; P, the tpxaary windings and S, the secondary windings;
HI, jEI2, etc., the spark pltigs; T, the timer; MP, the master primary; V, the vibrator;
W, tiie common primary connection;, 1, 2, etc., the stationary contacts of the timer.
The primary windings are all united in parallel at the top by a wire W, and with the
lower ends connecting respectively with the segments of the timer T. The i>rimary
winding MP which operates the vibrator V is ia series with this winding, the wire Wt
connecting from the battery and passing directly through the master primary MP. The
four condensers, CI, C2, 03 and C4, are in parallel witn the primarjr windings. Each of
the secondary windings S connects direct to the spark plugs, designated respectively
HI, H2. H3 and BaT^
is that there is but one vibrator to keep in adjustment, since
this vibrator serves for all the cylinders; whereas, with one for
each unit, all have to be kepj in adjustment and the diflSiculty
of keeping the several adjustments is a considerable factor. The
diagram, fig. 3,997, illustrates the circuit and operation of a
master vibrator. r^
2,780
HAWKINS ELECTRICITY
Synchronous Ignition. — ^Thls system employs a distributer
and a single coil for a number of cylinder. It is called "syn-
chronous" for the following reason: when a multi-cylinder en-
gine has a coil unit for each cylinder, it requires the adjustment
of several vibrators. Now, the time required by the vibrator to
act is variable with the adjustment and with slight differences
BftTTERY
Fig. 3,998. — ^Diagram illustratinsr the principles of synchronous ignition. For clearness t]i0
primary and secondary elements of both the coil and the distributer are shown separated.
When the primary rotor of the distributor comi>letes the primary circuit, current from
the battery flows and the vibrator operates, malong and breaking the current with great
frequency. A high tension current, made up of a series of impulses, is induced in the
secondary circuit and distributed by the rotor arm during its revolution to^ the several
cjrlinders in the proper order of firing. Each secondary segment of the distributer being
wired to one of the spark plugs, the rotor during its revolution brings each plug into the
secondary circuit in the order indicated in the diagram. As shown, the secondary rotor
is in contact with segment number two which causes the induced current to flow from
the secondary winding, through the distributer. One end of the secondary winding is usually
connected to one end of the primary winding instead of making a separate connection
to the metal of the engine. This smiplifies the wiring by having one common groand
oonnection. ^ r^
GAS ENGINE IGNITION 2,781
in construction, hence, of the several vibrators, perhaps no two
will act in exactly the same time. Consequently, though in the
ordinary multi-unit coil system, the closing of the primary cir-
cuits may occur at exactly corresponding moments for all
cylinders, the production of the spark will be more or less
"out," owing to the variation in the "lag" of the different
vibrator.
With a distributer and single coil, the lag is the same for all
the cylinders, hence, the application of the word synchronous.
Fig. 3,998 is a wiring diagram showing the connections of a S3mchronous.
system; for clearness, the two windings of the coil are shown separated
from each other and for the same reason also the primary and secondary
elements of the distributer are separated.
Magneto Ignition. — ^There are numerous types of magneto
used for igniting purposes. In the several systems, therefore,
different methods of wiring are required. In the true high ten-
sion and the self-contained types where the coil and condenser
are a part of the magneto, the number of external connection
is less than with those having the coil in a separate box.
In starting an engine equipped solely with a magneto, it is necessary
to turn the crank much f ^ter than when a battery is used, because the
armature must be turned at a certain speed to generate the required
current. Due to the refinement of design this factor has been reduced
and most magnetos will give a spark sufficient for ignition even if the
armature be revolved quite slowly.
To sectu'e satisfactory ignition with a magneto it is v&ry essential
that the various joints of the primary circuit be kept in perfect condition.
NOTB. — ^In connecting up batteries and coils it is recommended that the vibrator screws
be made "positive." so that whatever platinum is carried away by thie arc ta&}r be taken
from the screw and deposited upon the contact point of the vibrator. The theory is that the
screw is cheaper and easier to replace than is the vibrator, and that, with this arrangement,
the vibrator point builds up rather than wears away, requiring only the smoothing off of the
extra metal deposited upon it to keep it in condition.
•NOTE. — The very slight wear produced upon vibrators operated from non-synchronous
alternating current ma^etos from which the current is in each direction for one-half of the
time, in the aggregate, is well known. Hence, when a battery is used, if the operator would
periodically change the direction of the current flow by reversing the two battery wires con-
necting the one which has gone to the positive pole, to the negative and vice versa, he wi]>
find that the wear of the vibrator points is reduced to a minimum. o
2,782 HAWKINS ELECTRICITY
that is to say : all termipals shotild be clean, bright, and finnly connected.
The interrupter contacts should he kept dean and true using a fine file
to square the surface, so that the entire surface of one contact will
touch the other.
The two brushes leadiiM; to armature coil must be kept clean, free
of oil and springs adjusted to secure good contact.
Most operators pay too little attention to the secondary circuit
contacts. These also should be kept clean, true, and springs properly
adjusted.
When an engine will not start on the magneto or requires unusually
rapid spinning to effect ignition, it is a strong indication that the
pnmary and secondary contacts are not in proper condition.
When a magneto ignition system fails, the trouble is almost always
due to faulty condition of the contacts.
Pig. 3,999. — PUixi^ slot for cleaning platinum contacts of Connecticut magneto intermpter.
The cup holdmg the interrupter or primary circuit breaker may be withdrawn from itf
housing. The slot serves as a guide for a sniiall flat file for cleaning and squaring the
contact points. By means of an adjustable gauge furnished with the magneto, the correct
opening of the contact i>oints may be determined. The interrupter is provided with a
smgle roller bearing against the cam pins, thus insuring accurate tmiing at any speed and
unaffected by centrifugal force. The advance lever can be connected at either side of
the magneto as the interrupter housing is reversible. The cams are renewable by a
half turn with a screw driver.
Dual Ignition. — ^As defined, a dual ignition system is one
having two separate current sources with some parts of the igni-
tion apparatus In common. Most magneto systems are exam-
ples of dual ignition, that is the distributer which forms a part
of the magneto is used to distribute the current from either the
magneto or a battery. Thus, if a short circuit occur in the arma-
ture, by turning a switch, current may be furnished by the bat-
tery and distributed by the magneto. Moreover, because of the
difficulty of cranking an engine fast enough to start on themagneto.
GAS ENGINE IGNITION
2,783
the battery is usually used for starting and the magneto for
running. An example of dual ignition is shown in fig. 4,000.
Double Ignition. — ^An extreme provision against failttre in
operation consists in providing two entirely independent igni-
tion systems. For some installations both make and break and
jump spark systems are provided, in others, two high tension
systems. Such practice is not to be recommended, especially
in view of the very efficient and dependable apparatus that can
now be obtained.
f^HUS m»TT6M TOR STARTIMfc
A
A a A :&
SP^PlH pLuBft
FOMfl, CQMaiMt&
Pig. 4,000. — Wiring diagram of Bosch dtial ignition system, using one set of spark plu^.
A special coil is provided with self-contained switch, and a button for bnnging a ma^etic
vibrator into the circuit when desired. Combined cables: 1, thin blue cable is for
contact breaker; 2, thin red cable for short circuiting terminal; 3, thin white cable for
high tension terminal ; 4 , thick brown cable for distributer terminal. Single connectione,
1 and 6 are battery leads. At back of coil is connection to frame.
Ignition with Special Devices. — ^The fact that ignition could
be made reliable and certain, as well as more nearly synchronous,
by the single spark as produced by the magneto, has influenced
2,784
HAWKINS ELECTRICITY
several seekers after battery economy with coil ignition to de-
velop and place on the market devices in which a single break
in the primary circuit is caused mechanically at each instant at
which it is desired to ignite the charge within the engine cylin-
ders.
These "single-break" coil systems embody, in their most highly
developed forms, a single plain coil, a secondary timing device for the
induced high tensioi current and a timer or circuit breaker which causes
a sharp break in the circuit of the primary coil winding each time an
ignition spark is required. After the coil itself, the circuit breaker is
the chief component of single coil systems with distributer, designed to
produce but one spark per ignition. Upon it depends the effectiveness
Pigs. 4,001 to 4,004. — ^Principle of the Atwater-Kent ignition system. The so called "oni-
sparker" consists of a notched shaft, one notch for each cylinder, which rotates at one-
half the engine speed, a lifter or trigger which is pulled forward by the rotation of the
shaft and a spring which pulls the lifter back to its original position. A hardened steel
latch and a pair of contact point complete the device. The figures show the operation
of the contact maker very clearly. It will be noted that in fig. 4,001 the lifter is beinjg
pulled forward by the notched shaft. When pulled forward as far as the shaft will carry it
fig. 4,002, the lifter is suddenly ptilled back by the recoil of the lifter spring. In returning,
it strikes against the latch, throwing this against the contact spring and closing the
contact for a very brief instant — ^too quickly for the eye to follow the movement (fig.
4.003). Fig 4;004 shows the lifter ready to be pulled forward by the next notch. Note
that the circuit is closed only an instant preceding the spark. No current can flow at
. any other time, not even if the switch be leit "On" when the engine is not running. Note
that no matter how slow or how fast the shaft is turning, the lifter spring will always
pull the lifter back at exactly the same speed, so that the operation of the contact, and
therefore the spark, will always be the same, no matter how fast or how slow the engine
be running. Tlie contact points are adjustable only for normal wear. By means of the
distributer, which forms the upper part of the unisparker, the high tension cterrent from
the coil is conveyed by the rotating distributer block, which seats on the end of the
unisparker, to each of Uie four spark plug terminals in the order of firing. ^
GAS ENeiNE IGNITION
2,785
of the spark, and in some measure also the current consumed in the
coil in producing; it.
In consideration of battery economy, it is necessary that the circuit
breaker make only a sufl&ciently long contact to secure the proper
building up of the magnetic field about the coil windings, before the
occurrence of the break. Because of this, it is usual to so set the adjusta-
ble point of the breaker that the contact duration is the minimum with
which a proper igniting spark can be secured. The author objects to
primary battery systems, except on some single cylinder engines, because
the current is of constantly decreasing strength and batteries of short
life, necessitating frequent renewal.
Fig. 4,005. — Auto coil wiring diagram showing coil box and connections. The picture shows
clearly how to bring the battery, timer and plug wires to the coil. The wires can enter through
the middle back or from the bottom of the coil box, through holes provided for the purpose.
It is important to connect the zinc or ( — ) batterjr wires to coil, the carbon or (+) wires
being connected to grotmd or frame of enp^ine. It is also important to shave or pare back
the braid on the secondary or high tension wires as shown in picture. If the braid be
connected to any metallic portion of the wire or terminal clip, there will be a noticeable
leak on damp days, as the oil in the braid sooner or later dies out, and the braid quickly
absorbs moisture, and moist braid will cause the high tension current to escape to the
frame of the engme.
Ignition Troubles. — ^To successfully cope with ignition
troubles there are two requisites: 1, a thorough knowledge of
the system used, and 2, a well ordered course of procedure in
looking for the cause of the trouble.
In many ignition systems the chief difficulty encountered in
the location of defects arises from the fact tha,t faults in^fferent
2,786
HAWKINS ELEOritlCITY
ni
^) "-" ^L^e^
Pigs. 4,006 to 4,011. — ^Knoblock coil wiring diagrams. Pig. 4,006, connections for malee and
break engine, showing battery, magneto and double switch. If ma^eto be not installed,
use a single switch in place of the double switch; Fig. 4,007, connections for single cylinder
jump spark engine using either vibrator or non- vibrator coil; fig. 4,006, connections for
jump spark coilwith three terminals; fig. 4,009, connections for two cylinder jump 8i>aik
coil: fig. 4.010, connections for three cylinder jump spark coil; fig. 4,011, connectioiis
for tour cylinder jump spark coil.
NOTE. — How to adj ust a vibrating coiL Good coils, when properly adjusted, consume
about one-quarter to one-half ampere for each engine cylinder. By screwmg down the ^ints
too close, the current consumption may be greatly increased to the detriment of the nuleage
and without any advantage. Therefore, it is advisable to see that the coil is adjusted so as to
take no more current than is necessary. To do this connect an ammeter in the place usually
left for a connection on a coil, or insert the ammeter in the battery connection, so that the
current flows from the battery throtigh the ammeter to the coil. Place a piece ofpSLper under
all but one of the vibrator pomts wiu the engine running. Adjust this pomt until the current
taken by its cylinder is a minimtun, without, however, any tendency to miss explosions. If
the engme will not run with only one cylinder working, the current taken by each contact
point may be determined by blocking this one point off with a piece of pai)er and noting the
change in the current that this causes. , Adjust the point and try this again, until the lowest
current consumption on which the engine will run properly is obtained. The proper voltase for
a battery in most cases is 6 volts. ^
GA3 ENGINE IGNITION 2,787
Ix>rtions of the drcuit sometimes make themselves manifest
by the same symptoms. If each defect had its individual symp-
tom, locating the trouble would be comparatively easy, but,
as it is, it is sometimes quite difficult to find the defective parts.
In general, the following method, should be adopted to locate
ignition troubles:
1. The source of current supply should be examined; if a
battery, each cell should be tested separately, and any one found
to be weak, removed. If a magneto be used, it should be dis-
connected, and the armature turned by hand; in case the field
magnets have not lost their proper strength, the armattire
should turn perceptibly hard during certain portions of each
revolution.
2. The primary circuit should be examined for breaks; all
connections made bright and secured firmly by the binding
screws, and the timer contacts cleaned.
3. The spark plug points shotild be cleaned and the air gap
made the proper length — about one thirty-second of an inch.
4. The vibrator contacts should be made flat and clean, and
the vibrator properly adjusted.
Testing the Spark Plug. — The spark plug should be unscrewed
and placed on the cylinder without disconnecting the wire to the
insulated electrode: the body of the plug only should touch the metal
of the cylinder. On cranking the engine the spark should be "fat"
if everything be in good condition; if a weak spark be produced it may
be due to either a loose terminal, run down battery, or badly adjusted
vibrator. When no spark can be obtained the entire system must be
examined and tested, befginning at the battery.
Plug Testing in Multi-Cylinder Engines. — ^AU nuts are removed
from the plug, leaving the high tension wires in place. After starting
the engine, all wires are grounded except one, thus running the en^e
on one cylinder. In case there be no misfiring after testing at vanous
engine speeds, it can be taken for granted that the plug is sotmd. The
remaining plugs are tested in the same manner. ^Hien a multi-unit
coil is used, a faulty plug may be located by holding down all the
vibrator blades but one, so that only one spjark plug operates. Running
. each cylinder separately by this means, it can easily be ascertainea
2,788
HAWKINS ELECTRICITY
which plug is defective. Some coils are provided with little knobs for
cutting out cylinders in the manner just described.
Complete Break in the Wiring. — ^The engine is placed upon the
sparking point, the primary switch closed, and the two tenninals of
the suspected wire touched with a test wire. A current indicates a break.
Partial Break in the Wiring. — ^A partial break, or one held together
by the insulation, may sometimes be located by bending the wire sharply
at successive points along its length, the
engine being at the sparking point and
the switch closed as before.
Primary Short Circuits.— The pri-
mary wires should be disconnected from
the coil, leaving the ends out of contact
with an3^hing. There is a short circuit
if on touching the switch points momen-
tarily a spark appear. A short circuit may
sometimesbeovercomeby clearing allwires
of contact with metallic bodies, and pull-
ing each wire away from the others which
were formerly in contact with it.
Pigs. 4,012 and 4 ,014. — Sumter testing device for testing low r ension circuits. To test magojeto,
snap the clips on terminals after disconnecting it from c intuit. The condition df magtiet<j
is evidenced by the brilliancy of lamp. To test a make and bTeak ignitor, snap ems diii
on insulated terminal and the other on the engine fmme. A little practice enablet tha
conditions to be determined by noting the varying brilliancy of the liUnp.
Secondary Short Circuits. — ^The secondary lead from the spark
plug should be disconnected. Under this condition the high tension
current may sometimes be heard or seen discharging from the secondary
GAS ENGINE IGNITION
2,789
wire to some metallic portion of the car. Water in contact with the
secondary wire will sometimes cause a short circuit tmless the insulation
be of the best quality.
The Primary Switch. — ^This portion of the primary circuit some-
times causes trouble by making poor contact. This is generally due
to the deterioration of the spring portion of the metal, which gradually
loses its resiliency. Snap switches sometimes fail through the weakening
of the springs which hold them in the "on" or "off position. The
contacts of a switch should be kept in good condition.
Primary Connections. — ^AU binding posts and their connections
should be clean and bright. The wires should be firmly secured to the
binding jxists, as a loose connection in the primary circuit is often the
cause of irr^;ular misfiring or the stopping of the engine.
Fig. 4,015. — ^Bosch vibrating duplex ignition; arrangement when employing battery of a
grounded lig hting or starting system, or separate battery for ignition.
NOTE. — Bo9ch vibrating duplex ignition. In the operation of this system the arrange-
ment is such that, while the magneto circuit is independent and complete in itself, the battery
circuit includes both the coil and the magneto. With the switch in the battery position, the
battery and coil are in series with the primary winding of the magneto armature, and the
current for the battery supplements that generated by the magneto. Thus there is induced
in the secondary winding of the magneto armature, a very powerful current, which, on
account of vibration action of the coil appears not as a single spark but as a series of
spark, the current is distributed in the usual way by the magneto distributer. The battery
nde is not intended to be used as a separate ignition system, but merely as an auxiliary
to the magneto to insure positive starting when conditions are not of the best. The
battery and coil are used in connection with the magneto only^ when starting, while for
regular running the magneto operates as an independent igmtion system. The coil ^ id
designed to operate over a range of from eight to sixteen volts, so that cars provided with
a storage battery for lighting, starting, or other purposes, if within the voltages mentioned,
can employ the same battery for the Bosch vibrating duplex system. If only a 6 volt
■torage battery be provided, this can be utilized in connection with the system by adding
three dry cells in series with the storage battery. Where no storage batteiy is available,
or where it is desired to keep the ignition battery separate from the starting, or lighting
batterv, dry cells alone majr be used to operate the system; in such case it is advisable
that the battery consist of eight or ten dry cella (preferably ten), connected in series.
2,790
HAWKINS ELECTRICITY
Vibration. — Since the wires are subject to constant vibration, a
number of strand of fine wire is better than a single heavy wire, ^s the
latter is more liable to be broken. In securing the wire to a binding post,
care should be taken that all the strands are botmd.
Timers. — These may giye trouble by: 1, presence of dirt, 2,* loose
contacts, or 3, division of the si)ark; this latter effect is sometimes
caused by metallic particles wearing off the revolving part forming a
path so that the spark passes from ttie revolving part to more than one
contact segment.
C!oil8.~The part of a coil which requires most freqtient attention
is the vibrator. The contact points are subject to deterioration on
account of the small spark always present betwe^i the points when
the coil is in operation. In time, the points become corroded and
TYPe'vO'COJL
ID 5RARK PLUGS
Pig. 4,016. — ^Bosch vibrating duplex ignition; arrangement when employing battery of anim>
groimded lighting or staging system.
burned, and therefore require to be resurfaced by smoothing with a
fine file. A faulty connection to the condenser is at once shown by lai^
sparks at the vibrator points. Any repairs to a coil, aside from tne
vibrator, should be done by an expert, as the construction is very delicate.
Igniters.— In make and break ignition, a failure to get a spark,
esp«aally with a weak battery, is frequently due to the tappet spring.
This spring must be quite stiff so as to cause the break to take place
with considerable rapidity; the more rapid the break, the better
is the quality of the spark. The contact ^points of the igniter
electrodes are subject to corrosion and wear. When they become pitted
the contact surf aces should be filed smooth. c>
GAS ENGINE IGNITION
2,791
SfMurk Plugs. — ^Repeated failtire to start when the coil vibrator
operates, indicates a faulty spark plug. A rich gasoline mixture dftea
leaves a carbon d^)06it,^ and being a partial conductor short circuits the
plug. The porcelain insulation, on account of its brittleness, may
cradc inside the sleeve, allowing a spark to pass there instead of at tlie
gap. Mica insulation sometimes becomes saturated with oil, causing
the layers to separate, permitting a short circuit.
Engine Misfires and Finally Stops. — ^This may be due to exhaus-
tion of the battery, and is indicated by a weak spark and very faint
vibrator action.
FKjS. 4,017 and 4018.— Wiring diagram of Eisemann type G4 magneto. Troub!e9 andremedtet.
It the engine misfire or refuse to start, it shomd be found out first whether the trouble
lie in the magneto or in the spark plugs. The latter should be examined first, as they
are the most frequent cause of trouble. If the missing be in one cylinder only, or in different
cylinders, the corresponding spark plug ^ould be examined to see that the gap be not too
large. Tliis gap between uie electrodes should be approximately \^ of an inch. Also
the spark plu^ ma^f be short circuited through carbon, or the insulation may be
cracked. Cleanmg with gasoline or replacing is the remedy. The wiring should be very
carefully examined and checked in accordance with the firing order of the engine. If
cables be cracked or worn, they should be replaced. Clean same with gasoline until the
contact surface appears quite white, or if pitted use a fine file — a manicure file will serve
the purpose very well — but file very carefully, so that the surfaces will remain sauare to
each other. The correct gap of the contact i)oints is %'* and in no case should it be
more than W'. As these contacts wear away in time, they should be regulated by giving
the adjustable screw **U** a forward turn, care being taken to securely tighten the lock
nut •* V". This can be accomplished without removing the timing lever or make and break
mechanism, as shown in figs. 3,978 and 3,979. The cut also shows the combination wrench
vriach is furnished with ^ich magneto and which includes a gauge for the regulation of
the gap between the platinum contacts (Ui'^). If the platinum contact riveted to the
contact spring *'17m", or that of the adjustable screw **lr' sho\ild be worn down entirely,
tt would necessitate a change of either or both. When the adjustable screw *'U** is replaced
or adjusted, care must be taken that the lock nut is securely tightened in place. If after
following these instructions, the engine still refuse to start, the magneto should then^be
tested by removing the distributer plate and resting a screw driver on the gear casing
holding same about W' fh>m the collector ring. Then, if upon rotating the armature,
a spark jump across the H'' g^^Pt it shows that the trouble does not lie m the magneto,
but in some other part of the engine, possibly the carburetter. If a spark do not jump
across the ^" gap previously mentioned, the magneto should be examined by an expert.
2,792 HAWKINS ELECTRICITY
Engine Suddenly Stops. — ^This is generally caused by a broken
wire or loose switch which does not stay closed. In the case of a single
cylinder, the broken wire may be either in the primary or second^
circuit; if a multi-cylinder engine, the break is in the primary circuit.
Engine Does Not Start. — ^Usually caused by: 1, primary switch
not closed, 2, battery weak or exhausted, 3, entire or partial break in
wire, 4, loose terminal, 6, moisture on spark plug, 6, folded plug, 7, spark
too far retarded or advanced, or 8, too slow cranking with magneto
ignition.
Engine Runs Fitfully. — ^Frequently results from a partial break
in the wiring, especially in the primary circuit,
Pre-ignition. — Caused by: 1, some smaH particle in the cylinder
becoming heated to incandescence, 2, the electrodes of the spark plug
becoming red hot, or 3, intermittent short circuit in the primary.
Engine Runs with Switch Open. — ^Usually caused by: 1, over-
heated engine or plug points, 2, defective switch, 3, an incandescent
particle inside the cylinder.
Engine Misfires. — ^This may be caused by: 1, weak battery, 2,
partial break in conductor, 3, loose or disconnected terminal, 4, inter-
mittent short circuit in the secondary, 5, faulty action of either timer
or vibrator contacts, 6, bent vibrator blade, 7, faulty spark plug, or
8, air gap too large.
Knocking of Engine. — ^Too much advance of the spark sometimes
produces this ^ect.
Knocking in the Cylinder. — The form of unusual noise commonly
described as "knocking" consists of a r^;ular and continuous tapping
in the cylinder, which is so unlike any sotmd usual and normal to
operation, that, once heard, it cannot be mistaken. Too much advance
of the spark sometimes produces this result. As mentioned by numerous
authorities, the placing of the spark plug in the exact center of the oona^
bustion space occasions a peculiarly sharp knock, which may be stopped
by advancing or retarding the spark from the one point of trouble.
This explanation of the trouble is questioned by others, and is probably,
over rated.
Knocking in Cylinder when Ascending Hills. — Carbonized
cylinder.
Loss of Power Without Misfires. — ^This ma^r be due to badly
adjusted coil contacts, poor spark, or incorrect timing.
Explosions in the Muffler. — ^These are usually caused by misfiring*
partially charged storage battery, or by one cylinder not working.
SELF-STARTERS AND LIGHTING SYSTEMS 2,793
CHAPTER LXXVI
SELF-STARTERS AND LIGHTING SYSTEMS
FOR AUTOMOBILES
In stmiming up the merits of the gas engine as a prime mover,
ttiere is one inherent defect that cannot be overlooked — the fact
that, on account of the nature of its cycle of operation, it is not
self-starting. It must be turned by some external force until
the proper mixture has been drawn into the cylinder: com-
pressed and ignited before it will start, unless perchance an
unignited mixture be left in the cylinder and the piston be in
the proper position; then by igniting the unbumed charge the
engine will usually start.
Glasses of Starter. — The engine starting mechanism requires
deep thought and engineering skill to properly apply it to an
automobile, that is, making it an integral part of the car, pref-
erably a part of the engine mechanism.
The various starting systems are classed, according to the
kind of power used, as: 1, mechanical; 2, compressed air; 3,
gas; and 4, electric.
The emplojnnent of electricity for starting has the advantage of
also supplying current for lighting and ignition as well, and this has
led to the development of systems involving various combinations. It
would seem, therefore, that electricity would be universally used for
starters, save for the fact that there are some objections, such as high
cost, maintenance, and the considerable mechanism necessary, that
offset more or less the advantages accruing from its threefold uses.
2,794
HAWKINS ELECTRICITY
Glasses of Electric Starter,— There are nmnerotis electric
starting systems, and they may be classified according to the
methods of obtaining current for starting and ignition, and the
power el^nent of the starter, as:
1. One unit systems;
2. Two unit systems;
3. Three unit systems.
FLY VfHZtL
Pigs. 4,019 to 4.022. — Classes of starter systems. Pig. 4,019, one unit system; i ^
umt system; fig. 4,021 so called two unit system; fig. 4,022, so called three umt system.
These several systems comprise respectively:
1. A motor-dynamo;
2. A motor and a dynamo;
3. A motor, a dynamo, and magneto all separate.
NOTB. — ^There are two classes of two unit systems as explained on page 2,802; a two unit
system and a so called two unit system. There is some confusion in classification, chiefly because
of the close relationship between the starter lighting and ignition systems. One unit properly
indicates a system with a motor generator and two unit^ a system with motor and dynamo
separate. -^ ' r^
SELF-STARTERS AND LIGHTING SYSTEMS 2,795
Electric Starters Require a Storage Battery. — In any elec-
tric system a storage battery is always necessary; for, in order
to crank a gasoline engine there must be some Source of electrical
energy from which the cranking motor may draw its supply of
electricity. Without it there wotdd be no electric cranking
Pig. 4,023 — Gould type B storage battery for starting and lighting systems. Plates 4^ X fi|&:
7 to 15 plates per cell. Battery units for 6, 8» 12, 16, 18 and 24 volts.
devices. The first function, therefore, which the storage battery
serves is to supply electricity for starting purposes.
NOTE. — ^The exide battery plates are of the grid type. , The grid is made of a stiff lead
alloy which supports the active material in the form of a series of vertical strip held between
Oie grid bars and locked in place by horizontal surface ribs which are staggered on the opposite
sides. After the grids are cast, they are * 'pasted' * with oxides of lead made into a paste of speciajl
composition which sets in drying like cement. The plates then go through an electric chemical
process which converts the material of the positives into brown peroxide of lead and that of
the negatives into gray spongy lead. Both the positive and negative plates are provided with
lugs and in assembly the positives and negatives are separted by wood separators ribbed
on the side against the positive. A positive and negative group, together with the separators
constitute an element. A rubber jar of special composition is used as a cell container. The
plates rest on stiff ribs or bridges in the bottom of the jar. ^ . ^
2,796
HAWKINS ELECTRICITY
Figs. 4,024 to 4,026. — State of charge of cell as indicated by the density of the solution. Pig.
4.024, cell f\illy charged; fig. 4,025, cell about half charged; fig. 4,026, cell almost dischaiged.
How to test with hydrometer: Remove vent caps from the cells. To use hydrometer,
squeeze the rubber bulb, then insert the end of the rubber tube in the cell and well below
the surface of the liquid; slowly release bulb, drawing the solution into the glass chamber
until the hydrometer floats freely. Note the point at which the hydrometer stem emerges
from the solution. Then slowly withdraw the tube from the solution and squeeze the
bulb to return the solution in the hydrometer set to the cell. The point at which the
hydrometer stem emerges from the solution denotes the density thereof. When the cells
are in good condition the density of the solution denotes the state of charge thereof.
The readings for various conditions of charge are 1,300, 1,225, and 1,150 for full, half,
and no charge respectively. In taking TeacUng; to prevent the hydrometer sticlang to
the side of the barrel, it sho\ild be held in a vertical position, the reading being taken at
the surface of the electrolyte when there is no compression on the bulb. In reading
the gravity of the different cells, it is customary to begin with the cell at the positive
end. When readings have been taken be careful to replace the electrolyte into the
same cell from which it was taken. Failure to do this often leads to trouble, that is,
electrolyte is often taken out of one cell, the gravity noted and tiie electrolyte put back
into another cell. The result is that the amount of electrolyte taken out of the first
cell is eventually replaced with water, leaving the electrolyte weaker; whereas the dee-
trolyte which was taken out and put into another cell would make the electrolyte of that
cell stronger, resulting? in irregularity in the different cells. ^
SELF-STARTERS AND LIGHTING SYSTEMS
2,797
When the car comes from the manufacturer, the storage bat-
tery will be filled with electricity, and it must be kept charged.
If a dynamo be provided on the car, this may serve to charge
the battery whenever the car is in use. Unless such a generator be
supplied, it will be necessary to periodically recharge the battery.
Batteries designed solely for ignition or lighting are not
capable of taking care of the sudden and large demand for cur-
rent to operate a starter.
PZG. 4,027. — ^Holtzex^Cabot lighting magneto as installed on model T Ford car. It must be
driven from the fan pulley. A special fan with magneto pulley is furnished with the
magneto. The battery is mounted under rear seat on right side; the usual running board
mounting is not recommended. A 60 ampere hour storage battery, if fully charged, will
operate the side and tail lamps (6 candle power total) for approximately 50 hours, or the
head and tail lamps (34 candle power) for approximately 10 hours. Turn off head lights
when car is standing.
Ques. What is the principal difference in storage bat-
teries intended for ignition, lighting, and starting?
Ans. Capacity.
The Ignition battery is inapplicable to either lighting or starting duty.
Just as the lighting battery lacks capacity for starting purposes, so does
the one used for ignition purposes, only that the latter is laclang in a
greater degree than the former. ^ ^^
2,798
HAWKINS ELECTRICITY
The construction of the ignition battery prohibits its use for
starting purposes; however, there is little difference in the con-
struction of lighting and starting batteries, hence a large
lighting battery may be used for starting.
Choice of Voltage. — In designing starters there are several
conditions to be considered in determining what voltage shall
be used, especially as the starter problem is somewhat different
JjKV h£aq lamps ^BP^^
TAIL
LAMP
Pigs. 4,028 and 4,029. — ^Holtzer-Cabot lighting magneto outfit installation, views showing
location of switch, ammeter, cut out and their connections. Pig. 4,028, one wire system
as applied to double bulb or turn down head lamps: fig. 4,229, two wire system, suitable
also as a general guide for motor boat wiring.
from the ignition and lighting requirements as to voltage, and
one battery is generally employed for all.
The pressure used on the different lighting and ignition
systems is six volts, and were it not for the problem of cranking,
there probably would not be any reason to change.
NOTE. — ^The essential requirement for rapid discharging is laige plate area pet ampete
discharged. This is just what is accomplished by the use of thin plates: for when two plates
replace one, the effective area is doubled. In practice this doubling of area is accompanied
by the reduction in thickness of plate, in order to keep the size of the battery about the same
as before. It also has an important bearing on the discharge rate which may be obtained
from a battery, and also the capacity or len^h of time that the battery will give this diachaiss*
The gain is due to the shortening of the distance which the electrolyte has to travel to tcm
the center of the plate. . ^
SELF-STARTERS AND LIGHTING SYSTEMS
2,7g9
Ques. What Is the advantage of low voltage?
Ans. The circuits are easily protected from electrical leakage.
Low pressure lamps are manufactured with less difficulty than
those designed for higher pressure.
Voltage of Units. — ^The weight of six volt batteries is less
than that of the higher voltage type. Were it not for these con-»
siderations, starting motors would be desif^ed for hi^h pressure,
Pig. ^jOSO.— ;Kfethcd of driving a genera tor direct trom engine fly wheel hy frieticfd pulley
with spting or cushion base'; the latter telievE^ th^ atriiss cm the shaft ftom excessive
vibTa.tioii. The governor r^uJatea the speed of the machme B-nd prevents burmug out
of the UmpSp The iltuigtratioD shows a. K-W magtieto installed on an early M^jcwell car.
as they are smaller and consequently lighter. High voltage for
the motor does not necessarily mean high voltage for the djniamo
and lights.
There are three general combinations:
1. All one voltage, either 6, 12, 16, or 18 volts;
2. Generating and starting at 12, 16, or 18 volts, and lighting
at 6, 8, and 16 volts respectively.
3. Generating and lighting at 6 volts, and starting at 24 or
30 volts.
2,800
HAWKINS ELECTRICITY
One Unit Systems.— The term **one unit'* as applied to an
electric starting system means that there is a motor and dynamo
combined in one machine, or motor dynamo, as it is called, the
dynamo furnishing current for the starter, and for charging
the storage battery.
UkMP COMBJNATION SWAP ^
^ SWt4TTRMiNALJUHC>
' SPEEOO^iETER'C
tmr
pHORKJJNDJCATCiRr"
m LltWSft^E LIGHT
HEAD
UGHT
Fig. 4,031. — ^Wiring diagram of Deaco single unit starting and lighting sjrstcm. Heavy lines
indicate No. 4 B. & S. stranded cable. Medium lines from motor generator and starting
switch to combination snap switch and terminal junction indicate No. 10 B. & S. gauge
duplex wire. Fine lines in lamp circuit indicate No. 12 B. & S. gauge duplex wire.
NOTE. — ^An example of the one unit arrangement is the Electro system, which has a
combined motor and dynamo, the latter furnishing current for starting ignition and lighting.
It is necessary to arrange the motor with a short driving shaft integral with the motor case,
driven either through the timing gears or sUent clmin and connecting to the starter with an
Oldham coupling. The motor dynamo is always in operation. When turning below 380
revolutions per minute it is a motor, and when turning above that rate, a dynamo. The com-
IX)und differential winding takes care of the output from the generator. No discriminating
cut out or reverse current circuit breaker is provided to disconnect the battery from the motor
djmamo entirely at very low speeds. Instead of this, the ignition switch breaks the line between
the battery and generatipr when the engine is stopped by cutting off the ignition. The system
operates on 24 volts, but charges the battery at six volts. TTie amperage drawn by the 24
volt motor when turning over the gasoline engine varies with the size of the motor as in all
systems. The gear reduction between the motor dynamo and the engine is twenty-five to one
when starting but changes automatically to a direct drive when the engine starts r un ning.
SELF-STARTERS AND LIGHTING SYSTEMS
2,801
O-MhMiS I ^
Q
Digitized
2,802 HAWKINS ELECTRICITY
In classifying a system as having one or more units, it means
that the apparatus provided for generating the current and the
motor for starting the engine consists of one or more parts.
Thus, as just stated, in the one unit system there is a combi-
nation dynamo and motor forming one machine, or "one unit."
tVo Unit Systems. — ^This classification indicates that the
motor and dynamo are separate units, as distinguished from the
Pig. 4,042. — Bntz single unit starting and lighting system. View showing mounting of motoi
generator on engme and so called silent chain axive.
one unit system in which they are combined. There is another
system, ill advisedly called two unit, consisting of a motor dynamo,
and a magneto. The reason for this confusion is because some
dynamos are arranged to furnish current for ignition when not
charging-the battery, thus ignition has to be considered in the
classification to distinguish the last mentioned system from the
arrangement of three independent units.
The Westinghouse system is an example of the first mentioned class
of two unit systems m which the cranking motor and dynamo are
SELF-STARTERS AND LIGHTING SYSTEMS
2.803
' 5 d u L, 'S J
t^^ S 5> S c." |J ^ M
Sea ^■'^nBa- t3 E ^--^H &
... s '"^'^ qH^ ^js-^ flT
Digitized by Vji,.> . ■ v '. :
2,804
HAWKINS ELECTRICITY
separate machines. The latter not only charges the storage battery
but sdso furnishes direct a supply of current for ignition. The dynamo
is of the slow speed type and turns at crank shaft speed on four cylinder
engines and 13^ crank shaft speed on six cylinder engines.
The battery circuit is cut in above 10 miles an hour and is cut out
below 7 miles per hour. This difference prevents the switch cutting
in and cutting out continuously when the speed of the car is at one
particular point.
Fig. 4,045. — ^Wagner dynamo of two unit starting and lighting sjrstem. The drive is throo^ a
train of gear or equivalent. The windings and internal connections are of such character
that no regulating devices are required except a cut out. In construction, the conuutt-
tator E and brushes P, G, H, and I, are located under the cover which in this cat is
removed. The brushes H and I collect the current from the commutator and furnish this
current for charging the battery through the cut out K. The brushes P and G collect the
current from the commutator and furnish this current for exciting the fields. The cot
out K is shown in detail in fig. 4.046.
A feature of the Westinghouse system is that the output of the
generator varies with the load. When the lamps are switched on, Che
output of the dynamo becomes great enough to take care of the added
SELF-STARTERS AND LIGHTING SYSTEMS 2,805
Pig. 4,016.— -Wagner cut out of two unit starting^ and lighting system. It eonaUtM of two
magnet coils L and M, wound on an iron core N, which attracts and rei)els an iron lever O.
At the end of O are two main contact points P and Q at which the contact between the
dynamo and battery is made and broken. There are also supplied two auxiliary contact
points R and S wmch are for the purpose of minimizing sparking at the main contact
points P and O. The coil M called the shunt coil is connected directly across the two
brushes H ancTl, and therefore the full dvnamo voltage is impressed across the ends of
this coil. The coil L, called the series coiU is connected in series with the battery and
dynamo and therefore this coil carries the charging current when the battery is being
charged. In OM^eration, when the engine is started, the d3mamo is driven by the engine
and it, therefore, increases and decreases in sjieed with the engine. When the engine
is speeded up, the dynamo follows with corresponding increase in speed and the voltage
of the dynamo rises as the speed increases. As soon as the dynamo voltage gets to a
point above the voltage of the battery, which is approximatelv six volts, the coilM pulls
the iron lever O toward the magnet core, thereby closing the contact at the points P
and Q-K and S. As soon as this contact is made, the dynamo is connected to the
battery, and a chaining current will flow from the dvnamo to the battery through the
series coil L, which is in series with the dynamo and battery. The dynamo continues to
charge as lon^ as these contact points P and Q-R and S remain together, but when the
engine speed is decreased, so that the dynamo voltage falls below the batteiv vol^ie,
the battery will discharge through the dynamo and therefore through the coil L. Thii
discharge current, being in the opposite direction from the charging current, wiU neu-
tralize the effect of coil M and allow the spring T to pull lever O away from the magnet
core, thereby opening the contact at the points P and Q-K and S. As soon as these con-
tacts open, the battery is off charge. The engine speed at Which this relay closes cor-
responds to a car speed of 7 to 10 miles per hour. ^ o
SELF-STARTERS AND LIGHTING SYSTEMS 2,807
load. This is accomplished by having the battery current go through
a series field on its way to the lamps, thus assisting instoid of bucking
or neutralizing the shunt field.
The reduction between the motor and the engine varies between
ten to one and twenty-two to one. The amperage on the jump or when
the starting switch is thrown in d«)ends on the resistance opposed
to revolving the engine, but will in the average case of a large fcur or
small six cylinder motor be 200 on the jump and about 80 for a running
amperage. The motor is series wound and is gejierally geared to the
fly wheel; it is operated by a switch which throws the gears into engage-
ment for starting, by first meshing them and then spinning the engine.
The motor is automatically thrown out of engagement when the engine
operates under its own power.
'Sterling Motttr
Sfsftfiif ffsfot
fi^^tful — * =
Figs. 4,048 and 4,049. — Diagrams of Westinghouse electrical and mechanical connections of
doable reduction motor and switch for automatic screw pinion shaft. Fig. 4,048, with
hand or foot operated starting switch; fig. 4,049, with electro magnetically operated
starting switch controlled by push button. In the figures, when the starting switch is
closed, the full battery voltage is impressed on the motor, and it starts immediately.
The pmion, when the motor is at rest, is within the screw shift housing and entirely away
from the flywheel gear. The thrjsaded shaft is connected to the reduction gear shaft by
a spring which thus forms a flexible coupling. As the load is not lar^e enough to com-
press the spring when the motor starts, the threaded shaft is immediately revolved by
the spring m released position. The pinion moves out on its shaft by virtue of the te-
volvixxg threads, tmtil it reaches the flywheel. If the teeth of tiie pinion and flywheel
meet instead of meshing, the spring allows the pinion to revolve tmtil it me^es with the
flywheel. When the pimon is fully meshed into the flywheel teeth, the spring compresses
and the pinion is then revolved by the motor as through a continuous waft, turning the
engine over. When the engine fires and the flywheel peripheral speed continuously
exceeds that of the driving pmion, it forces the latter out of mesh, and it is returned to
its original position in the screw shaft housing. During ^e periods immediately after
tiie engine has passed over any one oi the i>omts of maximum compression, the spring
offers an elastic cushion between the flywheel and tiie reduction gear so that the pinion
will not be thrown out of mesh. - o
2,808 HAWKINS ELECTRICITY
The "Aplco** is a so called two unit system in which the motor aad
the dynamo are contained in one unit ana the magneto forms the second
unit. The make of the magneto is optional and is separate and dis-
tinct from the lighting and cranking systems.
A widely different voltage is used in the cranking motor and the
djmamo. The former operates at 24 volts (except in one instance,
where 30 volts are used), while the latter operates at 6H volts.
The djmamo is of the low speed tjrpe, being driven at crank ^laft
speed by chain or any other suitable means. It furnishes current
for the battery above a car speed of eight miles an hour and charges
the battery until it becomes fully charged, when it is automaticsdly
switched off, and does not charge the battery again until the latter
drops below a point which can be fixed to suit the ideas of the manu-
facturer.
A discriminating circuit breaker or reverse current cut out operates
when the voltage of the dynamo drops below that of the battery. The
24 volt series motor acts through a reduction gear of 40 to 1 between
motor and engine.
, T^ee Unit Systems. — This division comprises those sys-
tems which have a motor, djniamo, and magneto each separate.
Here, each unit has a single function and is only electrically
associated with the rest of the apparatus in the system. Thus,
the dynamo supplies current for charging the battery, which in
turn delivers current to the motor and ignition system at start-
ing, and also to the lighting system, the magneto furnishing
current for the ignition system, when the engine is running.
In the manufacture of three unit systems, some make the
entire outfit, others manufacturing only motor and dynamo,
leaving it optional as to the make of magneto employed.
NOTE. — ^The following description of the Disco will serve as an example of the three
imit system. The motor and dynamo are both of the same size, each operating at 12 volts.
The altmiinimi cases are interchangeable for each unit, the entire difference being in the
windings, which are simple series on the motor and compound on the dynamo. The dimamo
does not come into action tmtil the speed of the engine has reached the i>oint at which tiie car
is traveling seven miles per hour. Below this point a cut out switch prevents anv connection
between the storage battery and the dynamo, and eliminates an^ possibility of a dischaige
to the generator. Below seven miles an hour ^e lighting current is drawn fiom the batt^,
which may be in any size desired over an 80 ampere hour capacity. The upper limit to the
chaxsin? point is about 25 miles an hour. Above this the dynamo is again cut out and has no
connection with the storage batterv. The motor generally is mounted so as to drive throofl^
teeth cut on the periphery on the nywheel. or it may be mounted on the one Mid of the engine
or the gear set. A roUer dutch is used which cuts out the motor as soon as the engine starts.
SELF-STARTERS AND LIGHTING SYSTEMS
2,809
The term three unit sjrstem applies only to "starting, lighting
and ignition systems," as distinguished from "starting and
lighting sjrstems."
-ToMttff.B"
(>
Ihfvfttinf C^nttcti Mt9^ Ht^ulatina Scnw
Coiwi
Amit^^m^^^^
Cutwt
Conttcfs
pjc. 4,050. — Diagram of connections of Westinghouse dynamo with self-contained rtgulator.
The iwilator performs two functions: 1, that of a cut out, and 2, that of a voltage regulatox.
Each function is performed by its individual element but the operation of the second
function depends upon that of the first. When the dynamo is being operated ai a
speed below the predetermined "cut in" speed, the contacts of the cut out are open, and
vtce versa. The cut in speed varies from five to ten miles per hour on high gear, dependkg
vtipom. the gear ratio and wheel diameter of the car. For voltage regulation, the sbuia
^ds of the dynamo are so designed that a voltage in excess of normal would be regulady
generated when dynamo is operated at high ^;>eed and no load. This excess voltage cs
me^^mted and the voltage is bdd constant by the autcKnatic voltage regulator. When the
avaamo is <^>erating below cut in ^>eed, the regulator contacts are dosed, and vemain
olosed till there is a voltage in excess of the pcedetermined value. This voltage is fixed
by the setting of the voltage regulatiiMr screw. When, due to increased speed of dynamo,
the voltage tends to exceed the value for which the regulator is set, the regulating contact
open, opening the direct shunt field circuit and cutting in the regulatingresistance. This
causes a momentary drop in voltage so that the contacts close again. This opening and
closing of the contacts is repeated so rapidly as to be imperceptible to the eye, and nolds
the voltage constant.
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HAWKINS ELECTRICITY
IRON
BALLAST
COIL
LAMPS
— o—
STORAGE BATTERY
SHUNT
FIELD
COIL
K^
IRON
BALLAST
COIL
IRON
BALLAST
COIL
Pigs. 4,051. to 4,053. — ^Thermal method of
obtaining self-regulation in the Roshmore
lighting system. As a current of constant
volume is desired, it follows that aelf-
i^ulation must be produced by change in
the volume of current rather than in the
voltage. The first clue to the solution of
the problem was f otmd in a i)eculiar prop-
erty by iron, of increasing greatly in elec-
trical resistance at a certain critical
temi)erature just below the ted heat.
Below this "critical" point the resistance
is practically constant. At and beyond
the critical temi)erature, the resistance
increases enormously with each degree of
temperature increase. Starting from thia
peculiar property of iron, the next thing
was to employ it correctly. The primitiv«
method would have been to insert a thin
coil of iron wire directly in the circuit and
simply waste the surplus energy at higher
speeds in heat as shown in fig. 4,051. This
however, would have given vcoy impeflect
regulation, besides necessitating a hea^
and clumsy machme, since the shunt fiufl
winding would receive the full voltaae
normal to the speed at any moment, to
keep down the strength of the cuiient in tte
afaunt fidd coil one terminal of the latter may be connected beyond the izaa **ba]laalf*
coil instead of between that and the armature and the "ballast" coil as in fig. 4.052. With
this arrangement better results are obtained, but, as the field excitation remains constant,
an excessive voltage will still be generated at high speeds. To counteract this, a bucking
coil is added, as shown in fig. 4,053, which reduces the field excitation. o
INC
SELF-STARTERS AND LIGHTING SYSTE^MS 2,811
Methods of CbntroL — ^In any electric system where there is
a dynamo and a storage battery, two control elements are neces-
sary for the proper working of the system:
Ftaii 4,054. — Ward Leonard ulil^.^^uj ^.^^.^ i _.. iiuiaiiiiituj^y rcgulatuig the charging of
the battery. When the car speed becomes approximatelv seven miles per hour, the
dynamo armature will give a voltage sufficient to charge the batteries. The circuit be-
tween the dynamo and the batteries is normally open, but when the voltage of the dynamo
becomes proper for charging, the coil A on the magnet core B, magnetizes the core
sufficiently to attract the arm C. This arm moves toward the core B and thus two spark
proof pbints D D' are brought together, establishing the circuit between the battery
and the dynamo, and the dynamo begins to charge the batteries. In a dynamo the dy-
namo voltage increases with the speed tmless a method of controlling it be adopted. The
dynamo shotdd charge at about seven miles per hour, but it is desirable that when the
car runs at a much higher si>eed, as 15 to 60 miles ^ hour, the dynamo voltage shall
not increase. If allowed to increase, such an excessive dynamo voltage would tend to
cause sparking at the brushes, excess current and consequent trouble at the commutator
and excessive wear and heating of the bearings. It would also cause an excessive amount
of current to flow through the battery. To prevent this, the strength of the dynamo
field, and consequently the output of the dynamo, is made dependent on the touching
cl the two points E E'. The coil P on the magnet core G carries the armature current,
and if this current become a certain amount (usually in practice 10 ami)eres) the core
becomes sufficiently maenetized to attract the finger H. This separates the contacts
B B' and a resistance M is inserted in the field circuit, weakening it. This causes the
amperes flowing through the battery to decrease. When the current decreases to a pre-
determined amoimt (say 9 amperes), the coil P does not magnetize the core G enough
to overcome the pull of the spring J. The spring J pulls together the points E E', me
full field strength is restored and the current tends to increase. Under operating condi-
tions, the finger H vibrates so rapidly as to keep the current constant. As a result the
dynamo will never charge above a predetermine amount (10 amperes), no matter how
hmli the speed of the car, but at aU speeds greater than a predetermined speed (about
15 miles i>er hour in practice), the dynamo will charge at a varying rate, which has a
maximum of 10 amperes and a minimum of 9 amperes. In case the engine speed become
80 low that the dynamo cannot charge the battery, the magnetism caused by the coil A
18 weakened so that the spring K pulls the contacts D D' apart. Thus the circuit between
the dynamo and battery is opened when the dynamo speed is too low for the dynamo to
charge. The auxiliary series coil L on core B acts to insure the ];>erfect demagnetization
of the core B on reversal of current. . ^^
2«812
HAWKINS ELECTRICITY
1. Means for preventing reversal of current when the dynamo
18 charging the battery;
2. Means for limiting the djoiamo voltage.
•
Ques. When dynamo is charging the battery and the
engine is slowed down, what happens?
Ans. Reducing the speed reduces the pressure induced in
the dynamo armature, hence, in slowing down beyond a certain
Fk*. 4,050.— Diagram showing circuit connection of Rushmore dynamo with automatic
cut oat. The construction of the cut out is shown on fig. 4,05i5. The ahunt field coil
18 oonnected beyond the ballast coil so that it receives current at all times at the constat^
ventage of the batterer, and another winding is added to the field. This is what electridana
call a *'bucking" coil, that is a coil so connected as to oppose the main shuqt field cofl.
This bucking coil, the effect of which is to reduce the field excitation, is connected as
a shunt across the iron ballast coil. Its resistance is considerably greater than that of
the ballast coil when the latter is cold or only warm, so that at low engine speeds prao
fioallY all of the current generated passes directly to the battery and lamps and the
machine acts as a simple unhampered shunt dynamo. However, the iron wire will allow
only a certain number of ampere to pass, after which it suddenly increases in resistance,
80 that any excess current cannot pass, but must go through the field bucking coil whicfa
thus, only at hi^ speeds, comes mto action and chokes down the dynamo exatation.
It wiU thus be seen that the output of the djmamo may be adjusted to any value desired
by simply employing an iron wire of suitable diameter in the ballast coil. At car speeds
below 16 miles an hour, the dynamo acts as a simple uncontrolled shunt wound machine,
while at the higher speeds, owing to the counter effect of the buckinfi^ coil, the resultant
excitation is less thaii the excitation due to the main shunt field coil alone. ,In order
to keep the current in the main shunt field coil as nearly constant as possible, it is con-
nected at a point beyond the ballast coil instead of directly across the brushes; then it
does not feel the fluctuations of voltage at the brushes. The effect of controllkig the
bucking coil by the current output is to produce an approximately constant current at
the higher s];>eeds. The voltage is determined bjr the storage battery, and is simply the
voltage required to force the specified current against the reverse pressure, plus the small
internJal resistance^ of the battery. Assuming the battery to be in good condition, the
dynamo voltage will be slightly in excess of the open circuit voltage of the battery, from
about 6)i to 6>^ volts, depending ui)on the state of charge. The battery is necessary
to control the voltage of any automobile lighting dynamo, and must never be discon-
nected therefrom while the dynamo is in use.
SELF-STARTERS AND LIGHTING SYSTEMS 2,813
X>omt, the pressure induced in the armature will become less
than the battery pressure against which it must force the cur-
rent in charging, and accordingly, unless some automatic device
be provided to break the circuit when such condition obtains,
the current will reverse and flow out of the battery.
Ques. What is the automatic device called?
Pig. 4,056. — ^Automatic cut out as used for Rushmore electric car lighting system.
Ans. It is properly called a discriminating cut out or reverse
current circuit breaker, and erroneously a relay.
Ques. Describe a discriminating cut out.
Ans. It consists of an electromagnet connected in the dy-
namo circuit, which, when the dynamo generates sufficient
pressure to charge the battery, will attract an armature and
close the circuit between the dynamo and battery, and which
will also open the circuit when the battery pressure becomes
greater than that induced in the dynamo. ^ i
•^ Digitized by LjOOgie
2,814
HAWKINS ELECTRICITY
Ques. What requirement is essential in charging a
battery?
Ans. The voltage of the d5aiamo must not exceed a certain
maximum, so that the charging rates do not become higher than
that proper for the battery.
Ques. How is this condition obtained?
Ans. By automatic regulation of the dynamo voltage.
Pig. 4,067. — Riiahmcire ballast coil with cover removed to show tbe mm wire; iUoitnitiioa
full size.
There are several ways of efifecting this regulation;
1. Mechanically;
2. Electrically;
3. Thermally.
These several methods are illustrated in the accompanying cuts.
An example of mechanical control is the Gray & Davis system,
where a clutdi and centrifugal governor are used.
The Ward-Leonard has electromagnet control, and in the Westing-
house there are two electrical fields, which oppose one another as tii6
speed of the dynamo increases.
The Rushmore system furnishes an example of thermal oontroL
Digitized
by Google
ELECTRIC VEHICLES 2,815
CHAPTER LXXVII
ELECTRIC VEHICLES
The term electric vehicle, is generally applied to a great variety
of either passenger or freight carrying machines which are pro-
pelled by electric energy supplied usually from storage batter-
ies, and in some cases from dynamos direct connected to gas
engines; the latter type, however, doe^ not include gas electric
combinations used on some electric railroads. ' ^'^
The principal types of electric vehicle which afe commercially suc-
cessful at the present time are:
1. Electric automobiles, represented by various types of roadster,
coupe, phseton, cab, etc., suitable for the use of physicians, business
men and others, in city service.
2. Electric trucks and vans for moving merchandise, and for deliver-
ing pui^ses.
3. Gasoline-electric trucks, which represent an "attempt to overcome
the lack of flexibility of internal combustion engine by combining it
with a dynamo and storage battery.
Electricity as a Motive Power.— Vehicles propelled by
electric motors, whose energy is derived from secondary bat-
teries, are preferred by some on accotmt of the combined advan-
tages in point of cleanliness, safety and ease of manipulation.
When well constructed and well cared for, they are also less
liable to get out of order from ordinary causes. Among their
disadvantages, however, may be mentioned the fact that the
storage battery must be periodically recharged from some
primary electrical source, which fact greatly reduces their sphere
of efficient operation.
2,816
HAWKINS ELECTRICITY
Since electric vehicles are not the prevailing type, charging stations
are in some localities few and far between which would make it impos-
sible tmder these conditions to make an extended tour from the base
of supplies. This difficulty cannot be overcome by carrying an extra
battery since the additional weight would curtail the speed and carry-
ing power of the vehicle.
It is impracticable to propel a vehicle by a battery of primary cell,
since such a battery of sufficient power would have little, if any, ad-
vantage in point of endurance over secondary cells, and when once
exhausted must be entirely replaced.
Light Electric Vehicles. — These are of various types, such
as roadsters, victorias, phaetons, runabouts and coupes, and are
Fig. 4,058. — Baker electric roadster. The general specifications are as follows: frame, pressed
steel; wheel base, 88 ins.; tread, 50 ins.; steenng mechanism, two types, one witn wheel
steer, the other with lever steer;^ controller, continuous torque type, six speeds forward
and three reverse; springs, semi-elliptic and full elliptic rear; battery, 34 cells, 13 MV
thin plate Exide, standard; tires, 32X4 special electric pneumatic front and rear or 34X4
cushion front and rear: brakes, two sets of internal expanding on rear wheels, operated
ind^>endently by two foot pedals; body aluminum, with side doors, open top, nickel and
black metal finishings throughout; painting, body black, blue, green, or maroon panels,
striping to match; upholstery, blue, green, or maroon leathers, or imported broadcloths,
standard; fenders, fml skirted metal curved fenders; equipment, two head lami>s, two
side lamps, tail lamp, side and storm curtains; volt ammeter and shaft odometer, full
kit of tools, special adjustable clear vision wind shield, electric horn.
equipped with batteries which have a capacity ranging from 75 to
100 miles per charge, with controller arrangements for providing
speeds varying from 6 to 25 miles per hour. In these cases the
number of cell in each battery may vary from 10 to 30 according
ELECTRIC VEHICLES
2,817
to the make and number of plate in each cell. The number of
plate in each cell naay vary to suit special conditions.
Electric Trucks for City Service. — Under certain trafl&c con-
ditions and surface requirements, the superior mobility of the
gasoline engine truck effects a saving in drivers sufficient to com-
pensate for the higher maintenance charges, but when the number
Pio. 4,059.— View of front portion of electric truck lowing electric winch which provides
mechanical means for loading or unloading, consequently reducing the time necessary
for this performance, especiaUy in the case of bulky and heavy articles, thus in some
instances increasing the total utility of the machine and operator.
of active truck is the same in each case, the electric truck is
sometimes the more economical.
The gasoline engine truck has the advantage in all classes of service
rejquiring a greater mileage than that which is conveniently obtainable
with the electric truck, but the greater portion of city delivery service
is well within the limits of the safe operative mileage radius of the
electric truck built at the present time. - o
2,818
HAWKINS ELECTRICITY
II
^m4
i *i ta \^ "Si B
i.
ELECTRIC VEHICLES
2,819
Gasoline-Electric Vehicles. — ^The principal disadvantage of
the gas engine for seK-propelled vehicles is its lack of flexibility;
while on the other hand, the principal disadvantage of the
electric vehicle operated by means of storage batteries is its
lack of mobility. It is evident that the short coming in each
case can be overcome only by combining the gas engine with a
dynamo connected to a storage battery, for suppljdng the power
reqtiired by the electric motors.
Pig, 4,061. — Interior Waverly front and rear drive electric brougham. The seating arrange-
ment of this type of electric duplicates that of the Waverly front drive four with the
addition of separate steering and controlling levers, and a separate set of brake pedal at
the left of the rear seat. The car in this way gains the advantage of dual driving systems,
a feature sometimes desired.
Such a combination will operate at practically constant speed at all
loads, as the dynamo with the storage battery serves to furnish the
necessary overload, or consumes that portion of the energy which is
not needed. Furthermore, the transmission will be entirely electrical
and will possess the simplicity and flexibility of electric control; while
the use of a motor will allow the attainment of various speeds by series-
parallel combinations.
Vehicles of this type are built in the form of omnibuses, surface cars
and trucks for city service and freight and passenger cars for interurban
railway service. The arrangement appears better adapted to the latter
service, than for propelling pleasure vehicles.
2,820
HAWKINS ELECTRICITY
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ELECTRIC VEHICLES
2,821
Electric Vehicle Essentials. — ^The three essential features
which convert a vehicle into an electric automobile are the
battery, the motor and the system of transmitting power from
the motor to the propelling wheels.
In order to move a body from one point to another, it is
necessary to apply power to overcome the various opposing
forces that always exist. In putting any body, say a carriage,
into motion, the effect of its weight, called inertia, opposes the
force producing the motion. Inertia requires an application of
Figs. 4,063 and 4,064. — Waverly alternative seatmg arrangements.
force directly proportional to the rate at which the vehicle is
accelerated. Besides this, there are several forces which are
active not only on starting and increasing the speed, but when
a uniform motion has been attained. These forces are: 1, wind
pressure; 2, internal friction of tires; 3, losses in the various
moving parts; 4, electrical losses in battery; 5, electrical
losses in wiring and motor; 6, gravity in ascending hills.
AU these forces which axe met when the vehicle is under motion
absorb more or less power, and, as in an electric machine the quantity
of energy that can be stored is limited, it is of the greatest importance
that the designing engineer should bear in mind the vital necessity of
cutting down these opposing forces as much as he possibly can.
2,822 HAWKINS ELECTRICITY
Wind Preesure. — ^The resistance of the air encountered by a
vehicle at normal speed is not a very serious matter, but with
an increase of speed or with a head wind, the loss becomes quite
large and racing cars are built with the idea in view of reducing
the area exposed to the wind and so shaping the exposed parts
that the machine will cut its way through with the smallest
amount of retardation.
Pig. 4,065. — ^Weston volt ammeter of the type used on electric vehicles. In some tjrpes, the
index is side by side instead of end to end.
Tire Friction. — The most important loss, perhaps, and one
that is least tmderstood is the effect of tires.
It is dear that the portion of any tire which is in contact with the
earth must be flattened, but in order to do this, not only must some
other parts of the outer surface of the tire assume a deformed shape
by creeping, but there must be a change in the relative position of tie
internal particles. If the tire be a double tube, j^neumatic, the inner
tube will rub against the casing and the casing mil have more or less
play against its fastening.
In every pneumatic tire, besides the rubber composition there must
be a certain amount of tough cotton fabric which gives the entire struc-
ture its strength. In most tires of standard make this material is in-
serted in the shape of canvas fairly closely woven and quite stifif. In these
tires the elasticity of the rubber is restrained and controlled by this
ELECTRIC VEHICLES
2,823
cloth, and it is readily seen that there is but little of the power of flat-
tening or adapting itself to the road that would oe possible by tiie
same tire were rubber used alone.
Thread and cx)rd fabric tires have been developed with the intention
of retaining the strength of the cotton and at the same time permit of
more freedom of motion than canvas will allow. The idea is to use
independent threads or cords and surround them with rubber. The one
layer of such threads being wound in the direction of the thread on a
right hand screw and the next layer at right angles to these. The
action of all the threads will then resemble very mudi a strip of loosely
woven cloth cut bias.
PiG. 4.066. — ^Interior of Borland electric. The driving seat is tilted forward to show the meant
of ready access to controller through the box-like base beneath the seat.
There are losses in the electric motor, controller and wiring which in
importance rank next to tire losses; besides the design of the motor
should be such that outside of the question of its own efficiency its
propelling power should be so regulated that the maximum distance
may be covered on a single charge.
In the design of electric vehicle the object of the builders should be
to attain the greatest possible mileage consistent with durability^ also
lightness, combined with strength and efficiency in every part. To
tms end manganese bronze, aluminum, seamless tubing and drop-
forged steel are the materials that are largely used. o
2.824
HAWKINS ELECTRICITY
Motors for Electric Vehicles. — ^These are of the enclosed
type of construction, which of necessity they must be, in order
to protect them from dust, etc., in their exposed positions under
the car. They are designed for heavy overloads.
Pig. 4,067. — ^Rauch and Lang electric vehicle motor. InatructionB far atre of motors
The two oil covers lead to the ball bearings in the motor yokes. A good grade of light
cvlinder oil is recommended for these bearings. The commutator, 10.320, should be at
sdl times kept clean, free from any gummy or gritty substance. The carbon brushes 7,076
should make perfect contact with the surface of the commutator and should be replaced
with new ones when worn out. These brushes are originally \% inches long and uiould
be replaced with new ones as soon as the measurement is reduced to IM mches. It is
safer to replace these brushes often, rather than allow them to become too short. Very
serious damage may result from using brushes that are too short or ones that make poor
contact with uie commutator. Brushes that are too short or that are making poor contact
will pit, bum and blacken the surface of the commutator. Replacement of brushes should
be made onlv by an experienced person. The motor leads are lead out of motor through
insulated holes. These noles, lettered J, H, B. A, S, E and P correspond to the letter con-
tacts on the controller into which they are connected. The motor brake may be adjttsted
for wear by means of the winged nut 14,350. Clearance between brake jaws and wheel
may be adjusted by means of the screw 14,271. To remove brake wheel from armature
^ft. take the fi« screw C out of the cap 14,481. A ^ inch, 12 pitch bolt, 3 inches or
longer, or a cap screw may then be screwed through the threads in the cap and up against
the end of the armature shaft. Continue to turn this screw and the pulley wiU Se drawn
off the shaft.
When a vehicle is started or its speed increased, a certain
amount of energy is absorbed to produce this acceleration. The
total amount of energy required is in proportion to the total
weight and to the square of the velocity, so that to double the
ELECTRIC VEHICLES
2,825
weight of a vehicle means doubling the power required for start-
ing, and doubling the velocity means four times the power.
Accordingly, to meet these conditions, especially when starting
under severe conditions, as on a sandy road, or in ascending a
hill, the electric vehicle motor is constructed for a 200% or
more overload.
As stated by one manufacturer, a motor for a two passenger runabout
rated at 2% horse power consumes 6,800 watts in ascending an 11 per
FlO. 4,068. — ^Waverly 80 volt motor, in eongtruction it is series wound medium
The armature rotates on ball bearings; four poles are used.
cent, grade at 7 miles per hour, although no more than 360 watts are
required to propel the vehicle on an even asphalt roadway at 8H niiles
per hour. These figures represent an effective power range of between
yi horse power and over 9 horse power.
There seems to be some tmcertainty as to the precise power rating
of vehicle motors, but, as a matter of fact, they are wound to develop
the highest constant power output at the lughest voltage used, with a
high overload capacity for short spurts, as in hill climbmg, etc.
Ques. What objectionable feature should be avoided
in electric vehicle design?
Ans. Very quick acceleration, becatise a vehicle>c6ififimcted
2,826
HAWKINS ELECTRICITY
with this featiire, not only gives the passenger an tmpleasant
jerk, but puts a heavy overdraft on the battery.
Ques. What are the considerations with respect to
friction in the bearings?
Ans. Since the amount of power lost by friction in the
bearings requires that much more power to be carried by the
vehicle, in order to attain the desired mileage or speed, it is
very essential to reduce frictional losses to a minimum by using
approved forms of ball and roller bearing.
Fig. 4,069. — Diagram of a single motor attached to rear axle through "herringbone" single
reducing gears. A, is the left hand section of the divided rear axle; B, the rig^t hand
section of the rear axle: C, the brake drum: D, the spiral pinion on the motor shaft
driving the worm gear, I, on the differential; £, plug for greasmg gears; F, set screw for
locking ball race; G, slot for wrench to adjust threaded nng, H, against ball bearings.
The Drive or Transmission. — Because of the relatively
high speed of the motor as compared with that of the rear
wheels of the car, a system of gearing is necessary between the
motor and rear axle to obtain the necessary velocity reduction.
Moreover, in some cases, other gears must be provided so that
ELECTRIC VEHICLES
2.827
the power may be appKed to the rear shaft when the motor
shaft and rear shaft are at right angles to each other.
There are several forms of drive, as by
1. Herringbone gear;
2. Chain gear;
3. Worm gear.
Fig. 4,070. — ^Waverly double reduction gear or combination herringbone gear and "silent"*
chain. ^ In construction the motor shaft is parallel to the intermediate or jack ^laft
and drive shaft. Two universal joints are used, so as to give freedom of motion in any direc-
tion. The motor weight is above the springs. The first reduction is by the silent chain
enclosed in a casing at end of motor; the second reduction is through the herringbone gear
in the axle.
Herringbone Drive. — ^This type of drive gear is extensively
used.
The method of attaching a single motor to the rear axle through her-
ringbone single reducing gears is shown in fig, 4,069. A and B, are the
two sections of the divided rear axle. The spiral pinion D on the
motor shaft drives the worm gear I, on the differential. C represents
the brake drum; E, the plug for greasing gears; P, the set screw for
locking baU race; and G, the slot for wrench for adjusting threaded
ring H, against the baU bearings. - ^
2,828
HAWKINS ELECTRICITY
The advantages of this sort of drive are its freedom from noise, its
simplicity and durability owing to the parts being enclosed.
Chain Drive. — This form of drive is desirable for heavy service,
as on very large trucks. It is a noisy and dirty mode of power
transmission, and when not enclosed is subject to rapid wear.
In chain drives there is more or less elongation of the chain due to
the wear of the rivets and bearings or to stretch of the materiaL To
guard against the latter, chain makers use special material of high
Figs. 4.071 and 4,072. — Diagrams showing the behavior of a chain on a sprocket of equal jpitdi,
and on one of properly unequal pitch. The following quotation from an Bnglish authority
explains tiie action: A chain can never be in true pitch with its sprocket. A pair of spttf
gears tend, to a certain extent, to wear into a good running fit with each other, but a
chain, if made to fit its sprocket when new^does not continue do to so a moment after
being made, as wear at once throws it out. This being so, it must be init up with, and in-
volves ^e consequence that a chain can only drive with one tooth at a time, supi^e-
mented by any frictional 'bite' the other links may have on the base of the tooth mter^
spaces. If tiie chain be made to fit these accurately (taking a roller chain for illustration),
it is obvious that the least stretch will cause the rollers AA to begin to ride on the teeth
as at BB. If, however, the teeth be made narrow cbmpared with the spaces between the
roUon, a considerable stretch may occur without this taking place. The roller inter-
spaoBS, then, ^ould be long, to permit the teeth to have some play in them, wfaUe re-
tailing sufficient strength, as shown in fig. 4,072. In order that the driving Q>rocket
may receive each incoming link of the chiun without its having to slide up the tooth face,
it uiould be of a somewhat longer pitch than its chain, the result being that the bottom
tooth takes ^e drive, this being permitted by the tooth play shown in fig. 4,072. This
difference, of course, gradually disappears as the chain stretches. The back wheel sprocket,
on the other hand, ^ould taJce the drive with its topmost tooth, and hence shotud be of
slightljr less pitch than the chain, but as the pitch of the latter constantly increases, it may
be originally of the same pitch. The only remaining point with regard to design, and one
which the owner of a car may easily ensure, is that uie number of teeth in the sprockets
should be prime to that of the links in the chain."
tensile strength, but if, for any reason, a link elongates unduly, it should
be replaced at once, as one long link will eventually ruin a chain. Such
elongation sometimes results from a sudden application of the load.
To prevent undue interference between the chain and sprocket as
the result of elongation, the sprockets are not cut to fit the chain accu-
rately but with a certain amount of pitch line clearance.
Ques. State a very objectionable feature of chain drives ?
Ans. The chain sometimes climbs the sprocket teeth.
ELECTRIC VEHICLES
2,829
Ques. What is the cause of this?
Ans. Considerable wear or too little clearance.
If a sprocket were cut without clearance, an elongated chain would
dimb the teeth and the latter would exert a wedging effect, thus sub*
jecting the chain to excessive strains. In design the amount of clear-
ance &ould be as large as is consistent with the proper strength of the
teeth.
Ques. Under what conditions should a chain operate?
Ans. It should work in oil, in a dust tight case.
/ REAR
JACKET ^HAFT
PlOTOB SHAFT
fK%\X.
REDUCTION
Fig. 4,073. — Double chain drive. .The rear axle is of the "dead" fype and each rear wheel has
a ^rocket with which the chains mesh. The jack shaft is parallel to the rear axle and uixm
the maintenance of parallelism between the two axles depends the satisfactory worlang
of the chain. The cut illustrates single and double reduction chain drive, r'or single
reduction the motor would be located at A, and for double reduction, at B.
Ques. What is the advantage of the chain drive?
Ans. The greater portion of the weight of the drive mechan*
ism is supported by the frame instead of the rear axle housing;
it is thus cushioned from shocks due to uneven road.
Ques. What two kinds of chain are used?
Ans. Block ch^ii^ and roller chain. digitized by CjOOgic
2,830
HAWKINS ELECTRICITY
Pigs. 4,074 to 4,077. — Details of Wood's electric vehicle construction. Fig. 4,074. moioir
Buapenaion showing detail of the hangers between which the motor is suspended; fig.
4,075, raditM rod connection, showing phantom view of radius rod and how attached
to rear axle housing. Also movmting of rear spring or radius rod forward to rear axle;
fig. 4,076, ateering knuckle, showing connections and half of front spring; fig. 4,077,
front apring showing full elliptic design and method of attaching springs to main < *
frame. " o
ELECTRIC VEHICLES 2,831
Ques. Describe a block chain.
Ans. A block chain is made of a series of block, properly
shaped to fit the teeth of the sprocket, each joined to similar
blocks before and after by side links bolted through the body
of the block.
Ques. Describe a rolled chain.
Ans. A roller chain is composed of a series of roller, known
as center blocks, joined by side links. Each roller rotates
on a hollow core which is turned to smaller diameter at either
end, to fit a perforated side piece joining the rollers into pairs.
The side, links are set oyer these side pieces and bolted in place
' through the cores.
Ques. How do the two types compare in operation?
Ans. A block chain with generous slack is liable to meet
the sprocket with a continual clapping, which at high speed,
becomes a continuous rattle. A roller chain is comparatively
free from the trouble.
Ques. What causes the snap and rattle of a chain?
Ans. The fact that even with the best designed sprocket,
as each tooth in turn passes out of engagement with the chain,
the next roller must be drawn forward through an appreciable
distance before engaging a tooth. This action not only pro-
duces the noise, but it is a factor in waste of driving power.
Ques. What attention should chains receive to main-
tain a proper working condition?
Ans. The principal points to be observed in the use and care
of sprocket driving chains are: 1, to maintain the proper ten-
sion in order to avoid ''whipping'* — which, particularly with a
long one, is liable to result in snapping of the chain, — and, at
best, involves a loss of driving efficiency. The chain should not
be drawn too tierht. lest a similar disaster result. Some slack
2,832
HAWKINS ELECTRICITY
must always be allowed, 2, two sprockets should always be kept
in alignment. In the case of a double chain drive, from a
cotmter shaft parallel to the rear axle, care should be exercised
to maintain the parallelism, even preferring a somewhat loose
chain to a tight one that strains ^^ft:-,^^f %s^ -
the countershaft, 3, if a link show j^^^// /L ^V \
signs of elongation, it should be ^^i^f/J //v^\ ^
^ ^^t^ replaced by
r^^^f a new one»
^i'i^^ 4, whenever
^^J" the chain is ne-
^iiP movedfordean-
ing or other pvn-
'f^i carefully replaced.
Y^s^/ so as to run in
ELECTRIC VEHICLES
2,833
as formerly, and with the same side up. The chain
should never be turned around, or its direction between the
sprockets reversed, 6* a new chain should not be put on a much
worn sprocket, 6, a chain should be frequently cleaned and rubbed
with graphite, because the chief difficulty involved in the use of
driving chains is the .liability to clog and grind with sand, dust,
and other abradants, and 7, after steady use for a more or less
extended period, the chain should be removed and cleaned
throughout.
Pig* -1,07 L>. — Rear view of Wood s' ch&SRts with battel^' showing the foHowing features of
construction: 1. radius rods extending from rear axle to sub-chassis frame; 2, rear
springs rest on radius rods, instead of on rear axle; 3, motor, showing ball and socket
spring suspension; 4, worm drive, showing location of worm below rear axle.
Ques. How may a chain be best cleaned?
Ans. After removing it from the sprockets, cleanse first in
boiling water, then in gasoline, in order to remove all grease
and dirt. The common practice is next to boil the chain for
about half an hour in mutton tallow, which is thereby permitted
to penetrate all the chinks between rolling surfaces forming an
2,834
HAWKINS ELECTRICITY
excellent inside lubricant. After boiling, the chain is hting up
until thoroughly cool, at which time the tallow is hardened.
It n^iy then be wiped oflE dean and treated with a preparation
of graphite, or a graphite alcohol solution on its inner surface.
Some authorities recommend that the chain, after it is cleaned in
boiling water and gasoline, should be soaked, first, in melted paraffin
for an hour at least, and then in a mixture of melted mutton tallow and
graphite. After each soaking, it is dried and wiped clean. With either
process, a daily application of graphite is desirable.
Pig. 4,080. — Chain and sprocket double reduction gear for heavy trucks. As here shown, the
motor is hung above the springs, missing the jars of travel.
Ques. Is It necessary that both chains be of equal
ti^tness?
Ans. No; the differential gear on the jack shaft will coun-
teract this and cause each chain to do its share of the driving.
Ques. What adjustment Is important with a chain
drive?
Ans. The jack shaft and rear axle should be noade parallel
ELECTRIC VEHICLES
2,838
by adjusting the radius rods to secure the proper engagement
of the chain with the. sprockets.
Combination Chain and
Gear Drive. — For very
heavy trucks where a con-
siderable reduction in speed
is required between the motor
and wheels, a double reduc-
tion is sometimes used as
shown in fig. 4,080.
The motor is usually hung
above the springs, thus being
protected from the jars of
travel.
There are several forms of
double reduction using light
high speed motors by means
Pig. 4,081.— Baker R and L worm and gear. of VarfoUS Combinations of
Fig. 4,082. — ^Baker R and L motor, propeller shaft, tiniversal joints, worm and gear. TUi
is the straight type top mounted worm drive.
gear and chain, with silent, roller chains or herringbone gears for
the first reduction, and single or double roller chains, bevel
gears or herringbone gears for the second reduction. ^'
2,836 HAWKINS ELECTRICITY
Worm Drive. — This is a very popular drive for trucks and
pleasure cars propelled by electric motors, because of the very
large reduction possible on single gear. It has the advantages
of silence in operation and great durability.
Ques. Describe a typical modem worm drive rear
axle construction.
Pig. 4,083. — Baker R and L worm drive transmission unit.
Ans. The worm wheel and differential gearing are assembled
as a unit with the cover of the axle housing. This housing car-
ries all of the weight, the driving shafts being full floating and
transmitting only the driving power to the wheels. A torque
rod takes all driving and braking tortional strain, while two
side radius rods relieve the rear springs of all tractive effort.
Annular ball bearings are used to take the radial and thrust
loads of the worm and wheel, while the road^heels run on
conical roller bearings. Digitized by G* ^
ELECTRIC VEHICLES
2,837
Storage Batteries for Electric Vehicles. — ^The storage bat-
tery has been modified in various ways to adapt it to automo-
bile use, the problem being to sectu-e the greatest specific energy
with the least bulk and weight. Its efficiency, or the amount
of electrical energy it will discharge in proportion to the amount
it takes to charge it is also an important consideration. Aver-
age figures run between 70 and 90 per cent.
FzG. 4,084.-*Lanchester type of worm drive as used on some electrics. An advantage
cls^ed for this form of worm drive is the fact that mounting the worm below the ring
gear permits it to be placed in a bath of oil, assuring constant and ample lubrication.
The storage batteries which have proved most successful in connec-
tion with electric vehicles are the lead sulphuric acid type, and the iron
nickel battery, commonly known as the Edison battery.
Ques. What construction Is employed to reduce the
wei^t of battery for use in electric vehicles?
Ans. The plate surface is finely divided.
TTie following methods are those most common: scoring, grooving,
laminating, castmg, pressing and by the ttse of a lead wooL o
2,838
HAWKINS ELECTRICITY
The Faure, or pasted type plates are ustially lighter and of higher
capacity than the Plante, but have a tendency to shed the material
for tne grid thus making the battery useless.
Mileage and Battery, — If the proper mileage per charge be
not obtained when all mechanical parts of the car are in good
order, it is undoubtedly due to the battery being undercharged
and not brought up to full voltage as indicated on the meter.
In this case it is best to discharge the battery until voltage indicates
1.8 per cell; open the hoods over the battery, remove plugs from cells
Fig. 4,085. — ^Waverly 42 cell lead battery. All battery cells are accessible from outside of car
by raising the hoods. The battery compartments are lined with acid proof material to
prevent acid reaching the paint, the running gear or other parts.
and cover the plates with distilled water to within one-half inch of
the inside top cover. Charge the battery in the usual way until it
reaches a maximum voltage as given on charging card, then charge
four hours longer at the lowest rate shown on the card. Try battery;
if this do not improve the mileage sufficiently, repeat the operation as
before. If after repeating the operation three times, normal mileage be
not obtained, and trouble be not found elsewhere the maker of the
battery should be consulted at once.
* Points Relating to Storage Batteries. — The following im-
portant directions should be carefully followed to obtain satis-
factory service for a storage battery:
• NOTE.— For a foU treatment of th« subject of storage bat^^nel,' k^ @^2& 4.
ELECTRIC VEHICLES
2,839
1. Keep
the battery
aiid connec-
tions clean.
2. Go over
the same and
see that they
are bolted up
tight.
3. If there
be any low
cells in the
battery, at-
tend to them
at once.
4. Keep
the electro-
lyte, or bat-
tery solution,
at the proper
height above
the tops of
the plates.
5. Keep
the density
of the elec-
trolyte, or
battery solu-
tion, at the-
proper point.
6. Do not
charge at a
rate that will
make the
cells exceed
100 degrees^
F. in temper-
ature.
7. A bat-
tery can be:
ruined in
three hours
after it has
been put in
use by being
left on charge
at a high rate
after it is^
fulP
ifiio
HAWKINS ELECTRICITY
8. The user of the vehicle should keep careful track of the charging
and, if possible, watch it personally.
9. In all cases follow strictly the instructions furnished by the maker.
10. Do not let battery stand completely discharged.
1 1. Do not let battery fully discharge in cold weather.
12. Do not let battery stand in a partly discharged condition long.
13. Do not go away on a visit ana allow battery to stand inactive.
14. A battety must be worked constantly to get satisfactory service
and when going away for two weeks or more, it is best to make arrange-
ments to have the battery looked after by someone familiar with it. ^
15. In charging, always connect the positive wire of the charging
source to the positive terminal of the battery and vice versa.
16. If the battery become dead, or lose mileage, consult the makers.
17. Charge battery in a warm room in winter.
18. In consulting the makers, be sure to give full particulars.
Pig. 4,079. — Gould cell showing parts.
Pig. 4,088. — Sectional view showing height to fill Gould starting and lighting; type of cell.
Battery Capacity. — ^As there is no sure way for the automo-
bilist to estimate the discharge capacity of his battery, he is
obliged to base such calculations as he makes on the figures
furnished by the manufacturers. With the help of his indi-
cating instruments, the voltmeter and ammeter.
Apart from any considerations of efficiency, the driver of an dec-
trie carriage should carefully bear in mind the figures supplied by
the manufacturers of the type of batt^ery he uses, in order to judge :
ELECTRIC VEHICLES
2,841
1. How long the present charge will last;
2. Whether he be exceeding the normal rate of discharge, and thus
contributing to the unnecessary waste of his battery and incurring other
dangers that may involve tmnecessary expense.
As a general rule the 1 hour discharge rate is four times that of the
normal, or 8 hour discharge, and considerations of economy^ and pru-
dence suggest that it should never be exceeded, if, indeed, it be ever
emphoyeaT The 3 hour discharge, which is normally twice that of the
8 hour, is usually the highest that is prudent while the 4 hour discharge
is the one most often employed for average high speed riding; batteries
give only the 3 and 4 hour discharge rates in specifying lie capacity
of l^dr products*
Fig. 4,089. — ^View showing Studebaker electric in home garase connected to rectifier charging
outfit. The subject of rectifiers has been treated at such length in Guide No. 6, that no
further explanation is here necessary.
NOTE. — High Charging Rate; — Occasionally it is desirable to charge a battery as
quickly as i>ossible, in order to save time, as when belated and far from home with an electric
vehicle that has almost reached its limit. As a general rule, such a procedure should not be
adopted unless the battery be thoroughly discharged. In charging a battery at a high rate,
the danger to be avoided is the tendency of the cells to heat. A battery should never be
charged at a high rate tmless it be cominetely exhausted, since it is a fact that the rate of
charge that it wul absorb is dependent upon the amount of energy already absorbed. As shown
in the table of high charging rates, the 96 ampere hour cell requires, for chaiginff in three
hours: For the first half hour, 70 amperes: for the second, 40 amperes; for the third, 30 amperes;
for the fourth, 20 amperes, and during the last hour, 10 amperes. It may also be charged at
the following rate in 45 minutes: 140 amperes for the first 20 minutes; 100 amperes for the
next 5 minutes; 70 amperes for the next 5 minutes; 33 amperes for the next 10 minutes; 10
amperes for the last five minutes. This is the rate to be followed when the battery is com-
pletely discharged. ^ o
2,842-
HAWKINS ELECTRICITY
The following data on sizes stiitable for automobile use will
be found useful.
Dltehargt in Amptrts
Anptro Hour Capacity
Normal
0«iM« DiMMlOM Cf
P«r Hour Durinfl
Whan Dlacharoad
Charijinfl
Jar In iMhM
8Hrt.
6 Hrt.
3 Hrt.
8 Hrt.
6 Hra.
3 Hrt.
Rata
Height
Ltnetk
WMth
6J<
8^
I2>4
50
4SH
37>i
6^
lofi
S'A
*K
7^
io>i
15
60
52>i
45
7H
II
1%
*H
^H
I2J<
i7>i
70
61X
S2}i
8j<:
I2«
7H
4^
lO
J4
20
80
70
60
10
12
6H
7
12 Ji
I7H
25
100
87 Ji
75
12^
12
6ji
7
15
21
30
120
105
90
15
li}i
6H
7
17H
24 Ji
35
140
122;^
105
i7«
ia}i
6H
7 .
20
28
40
160
140
120
30
12J4
9>^
5^
22^
31 Ji
45
180
157;^
135
«>i
I2JS
9
6>i
25
38 Ji
50
200
175
150
S5
I2J4
9
f^
27«
55
220
192>i
165
47^
laji
9
51^
30
42
60
240
210
180
30
12>i
9 .
6H
37ji
52>i
75
300
262^
225
37)i
I2H
9;'i
l^
45
63
90
360
3IS
270
45 ,
I2ji
9 ,
m
S2H
yyA
105
420
367>^
315
52|4
laji
ri>l
8
NOTE. — ^The figures will vary for different rates largely due to the niunber of plate per
jar and to other points of construction.
As given by a well known vehicle manufacturer, the following data on dis-
charging and rapid charging of agivenmakeof battery will befound typical:
Ampere Hour Capacity
T5«
Rata In Amperes for
Rata In Amperes for a
Discharged
1-
IP
6
a 3 Hour Charge
46 Minute Charge
3Hr.4Hr. 6Hr. 6Hr.8Hr.
HHr.HHr.HHr.^Hr.lHr.
20M. 6II.6II. 1011.511.
34 38 40 42 48
36 20 16 10 5
72 52 36 16 5
45 50 53 55 64
66 73 v8 81 96
8
48 28 20 16 7
96 68 48 20 7
12
70 40 30 20 10
140 100 70 30 10
112 124 132 137 160
20
128 68 52 32 17
238 170 119 51 17
140 15 > 165 171 200
25
150 86 62 42 21
300 214 150 64 21
168 186 198 206 240
30
178 102 76 50 26
356 254 178 76 26
196 217 231 240 280
35
208 118 90 60 30
420 300 210 90 30
NOTE. — ^It IS customaiy to state the normal capacity of a cell in ampere hours, based
upon the current which it will discharge at a constant rate for eight hours Thus a cell which
^oll discharge at 10 amperes for 8 hours without the voltage falling below 1.75 per cett is said to
have a capacity of 80 ampere hours. It does not follow that 80 amperes would be eecuied if
the cell were discharged in 1 hour. It is safe to say that not more th^ 40 amperes would be
the result with this rapid discharge. The ampere hour capacity decreases with the increase Is
current output. Generally speaking, the voltage during discmarge is an indicatioii of tbe
quantity of electricity remaining within the cell.
ELECTRIC VEHICLES
2,843
Electric Vehicle Controllers. — ^The form of controller
adapted to electric vehicle use consists of a rotatable insulated
cylinder carrying on its circumference a number of contact,
arranged to make the desired connections with the terminals of
the various apparatus in the circuit through a wide range of
variation.
Pig. 4,090. — Diagram of the controllmg apparatus of a light electric vehicle. A, brake pedal;
B, ratchet retaining pedal in place, operated by left foot; C, dash board; D, body sill; Ej
steering handle; F, controller handle; G, rocker shaft for setting hub brakes; J, brake
band on wheel hub; H, rear axle.
Some controllers are constructed with a cylindrical surface,
upon which bear single leaf springs, the desired electrical con-
nections being made by suitably connected conducting stirfaces
on the cylinder circumference, and cut outs being similarly
HAWKINS ELECTRICITY
lplifp|l|i!-
rliiesisi litis!
Jy.^:6by\ji ^UVlC
ELECTRIC VEHICLES
2,845
accomplished by insulating svirfaces, bearing against the spring
contacts at the desired points. This type of controller is one
of the most usual forms for motor vehicle purposes.
As is obvious, it is possible to so arrange the electrical connections on
the controller surf fees, that by proper contacts with the terminal springs,
reversal of the motor may be accomplished. This is done in a number
of controller, the reverse being accomplished at a definite notch on the
quadrant of the shifting lever.
Figs. 4,094 and 4,095. — Baker R and L selective dual controller, control handles, resistance
and motor brake. General care: keep the plates 9,522-B and 9,525-B on the face of
the controller and the shoes 7,513-A on the movable arm clean and free from burned and
rough edges. The contact plates 9,522-B and 9,525-B and the shoes 7,513-A are the
ones that become damaged first. They are removable and when badly worn may be
replaced with new ones. Instructions for adjustment of motor brake arwd con-
troller to controller handle. Set the controller arm fingers 9.513 in neutral position,
as shown in cut, remove key from controller handle 66,267 and piill handle back to brake
position and then push it forward to the stop, which is its neutral x)osition. Ha^e the
drivers seat locked in forward running position and then the connecting rod 66,706 may
be adjusted to such a length that the handle 66,267 and the controller arm fingers 9,513 will
be in their respective neutral positions at the same time. After the above adjustments
have been correctly made, the forward driver's seat should be turned to the position it
will assume when car is to be operated from the rear seat and the length of the connection
rod 66,750 adjusted to such a length that both controller arm finders 9,513 and the rear
controller handle 66,261 will be m their respective neutral positions at the same time.
When these adjustments are correctly made the front driver s seat will turn freely from
forward driving position to rear driving position at the time that both controller handles
66,267 and 66,261 are in their neutral positions. Adjust motor brake shoes for wear
by means of the winged nut 14,350. Clearance of shoe is obtained by the adjusting
screw 14,271. These adjustments should be such that the brake is perfectly free when
controller arm fingers 9,513 are in their neutral position, as shown in cut. Whan brake
is applied the top finger 9,513 will have traveled upward acrossjthe contact plate, 9,525-B,
and just to the plate 9,529. The wires leading from the controlling resistance 18,870 are
marked to correspond to the connectors on the side of the controller into which they are
connected.
o
2,846
HAWKINS ELECTRICITY
[WlWfTfT
FIELDS
[|t|IH|i|p
ARMATURES
-^>xy ■
6E. 6p 66
o
JC»
c^^^
REVERSine SWITCH
-<^* <i:s..f 9''
Pic. 4,096.-;— Diagram plan of the several parts of an electric vehicle driving circuit. The
field windings and armatures are shown projected, the prober wiring connections being
indicated. The periphery of the controller is laid out withm the broken line rectangle,
the contacts and connections through it for varying the circuits through four speeds
being shown. For first speed the controller is rotated so that the row of terminal points,
A, B, C, D, ^, F, G, are brought into electrical contact with the row of terminal points,
on the controller, A', B', C, D', E', F', G'; this connects the two unit battery in parallel
and the field windings of the two motors in series. A further movement of the controller,
bringing the points. A, B, C, etc., into contact with A>, B', C*, etc., gioem meeond 9peed,
the batteries now being in parallel and the fields in series parallel. For third apeed, the
points B and C are brought into contact with B* and C», and E and P with E* and F*,
which means that the batteries are connected in series, and the fields in series. Similarly,
for fourth speed, the points B and C are brought into contact with B* and C*. and D, fi,
P, G, with D*, E*, F*, G*, which means that the batteries are in series and the fields in
parallel. The connections between the battery, the armature brushes, and the motor
fields, are made as indicated through the rotary reversing switch by the terminals. K, L,
M; N. Thiw switch may effect the reversal of the motors by giving a quarter turn to its
spmdle, which means that the contacts of segment X, will be shifted from L and K to K
and N, and the contacts of segment Y, shifted from M and N to L and M, thus reversing
the direction of the current.
ELECTRIC VEHICLES
2,847
Electric Vehicle Circuits. — ^The methods employed to vary
the speed and power output of an electric vehicle motor consist
briefly in such variation of the electric circuits as will modify
the pressure of the batteries on the one hand, and the operative
efficiency of the motors on the other.
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Fig. 4,097. — Diagram of controller connections of a one unit, one motor circuit, with variable
fields.
The cells comprising the storage battery are so arranged as to form a
number of unit, being so wired that by the use of a form of switch
known as a controller, the connections may be varied from series to
parallel, or the reverse, as desired. The same arrangement for varying
the circuit connections is used for the field windings.
The wiring diagrams, ngs. 4,091 to 4,093, show one arrangement. The
dotted lines on each figtire indicate the circuits that are cut out or open,
and the full lines those that are active or closed. o
2,848
HAWKINS ELECTRICITY
Ques. How may the circuits be arranged with two
batteries and two motors?
Ans. For this combination, as shown in figs. 4,102 to 4,104,
it is possible to eliminate the resistance coil altogether and
depend entirely upon the circtiit shifting for regulating the
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Pig. 4,098. — Diagntm of controller connections of a fotir unit one motor circuit, with constant
series connections for fields and armatures in forward and backward speedJs.
voltage and power. Accordingly, for the first speed the bat-
teries are connected in parallel, and the armatures and wind-
ings of the two motors in series. For the second speed, the
series connections are adopted for both batteries and motors,
while for the third speed the batteries are in series, with the
motors in parallel.
ELECTRIC VEHICLES
2,849
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Figs. 4,099 to 4,101. — Diagrams showing methods of speed changing in a typical one battery
nmt( two motor circuit. The Ant »peed shows the two motors m series, with a resistance
coil mterposed: the eeeond, the motors in series, without the resistance; the third, tke
motors in parallel.
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Figs. 4,102 to 4,104. — Diagram showing methods of speed changing in a two battery unit,
two motor circuit, showing combinations for three speeds. The Aret epeed is obtained
with the battery units in parallel, and the motors in series, the second, with the battery
units in series and the motors in series; the third, with the battery units in series and the
motors in parallel. ^ ^
2,850
HAWKINS ELECTRICITY
, How to Operate an Electric Vehicle. — ^The following in-
structions, which are given by one maker, will be found to
apply for the most part to any car.
1. Be seated.
2. Place steering lever in position to give ready control.
3. Insert key in controller handle and unlock.
4. Pull controller handle back to brake or off position and raise slide.
(This closes the circuit and electric is ready to move.)
5. Be sure that the foot brake is released.
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Pigs. 4,105 to 4,107. — Diagrams showing combinations for three ^eeds in a typical four
battery unit, single motor circuit. The only changes made in these circuits are in the
battery connections. For the first speed the battery units are in parallel for the
second, in series parallel, for the third, in series. The motor connections are not varied.
6. Forward movement of the controller handle gives two starting
speeds and three running speeds.
7. To stop electric, pull controller handle backward past off position.
First the electric brake will come into action and then a mechanical motor
brake.
8. To reverse, bring electric to standstill. Press down the foot lever.
Move controller handle forward same as when running forward. Two
starting and one running speed will be obtained when backing.
9. To stop reversing, puU controller handle to extreme backward
position. Take foot off reverse lever, which will automatically return
ELECTRIC VEHICLES
2,851
to forward positioh and electric is ready to be operated in a forward
direction.
10. Steering: Push steering arm from you to turn to the left and pull
steering arm toward you to ttim to the right.
11. When leaving the electric, be sure to always force down slide of
controller handle and take key out of lock.
12. Release foot brake before applying power.
13. To charge batteries:
a. Be stire that slide of controller handle is down and key out of lock.
. b. Insert charmng plug in socket at rear of electric and if the connections
from the plug to the changmg source be correct the ammeter should show read-
ing below the zero on the scale.
Figs. 4,108 and 4,109. — Chaiging an electric in front of city residence; fig. 4,108 shows mercury
rectifier located in basement under steps. With this arrangement the car may be charged
at the curb during idle hours of the day.
£. Follow the instructions for charging and care of battery that are furnished
by the manufac turers of the battery.
NOTE. — There are two push buttons in the floor of the car that may be
operated by a slight pressure of the left foot. One increases the speed of the car
and the other lights the meter lamp.
NOTE. — Baker R and L motor and control. The motor is designed to receive the
ccMnbined voltage of all the cells in the battery, i. e., the battery is at all times in series and
as the voltage is 2 volts per cell, the running voltage of the models equipped with 41 cells
would be 82 volts and on those models having 42 cells the voltage would be 84 volts. The
object of this is to eliminate the usual troubles caused by all unbalanced conditions of the
battery as when several sections are operated in parallel. The first i%peed includes a high
resistance and is intended for starting auty alone. The second speed has less resistance and
although intended to grade the startmg is convenient for occasional use in congested districts,
but too slow for ordinary running. The next stop cuts out all the resistance and the motor
runs on the series fields alone, the two sections being in series. The next or fourth speed
parallels the two sections of series field. On the fifth speed the series fields are in parallel
with an external shunt resistance across them. This weakens the strength of the series fields
and reduces the resistance of the circuit. The sixth or highest speed of the car is obtained
by means of an accelerator button located in the floor of the car. Its action is that of a switch
closing the circuit of a light shunt field on the motor. The direction of the flow of current in
this field is such that its strength opposes that of a series, thus weakening it and producing an
increase of speed on light running; but due to the differential action between the two, a very
great dropping off in speed occurs when climbing a grade or traveling a heavy road. In this
manner great driving jwwer and low current consumption is obtained on the grades on the
highspe«i. ^ ^
2,852
HAWKINS ELECTRICITY
Electric Vehicle Troubles. — In order to properly cope with
the numerous disorders and mishaps likely to be encountered,
the following points relating to troubles may be found helpful.
1. If vehicle run too slow, look for the following:
a. Deflated tires.
b. Slow tires, due to other makes having been substituted for those furnished
by the manufacturer of the vehicle.
c. Broken bearings in wheels, countershaft or motor.
d. Shoes not making perfect contact on face of controller.
Pigs. 4,110 and 4,111 Broc control lever lock. Pi^. 4,110. locked, safety plunger pushed down;
fig. 4,111, ready to operate safety plunger raised. To unlock, insert and turn the key,
move control lever back to power on position, and pull up safety plunger,
e. Brushes not making perfect contact on commutator due to being too short,
or commutator being dirty. *
/. Broken battery jar, solution having partly leaked out.
g. Brakes rubbing when they are supposed to be thrown off.
h. Battery exhausted.
2. If the current be higher than usual when running on the level, look
for the following:
a. Tight bearings.
b. Brakes rubbing.
c. Silent chains too tight.
d. Front wheels out of alignment.
e. Tires deflated.
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ELECTRIC VEHICLES
2,853
3. If needle on ammeter vibrate more than usual, moving up and
down very rapidly, look for the following:
a. Blackened commutator.
b. Commutator brushes worn too short.
c. Loose connections at battery terminals or at connections on controller.
d. Broken wire leading to meter.
4. If vehicle refuse to run, look for the following:
a. Broken jar in battery.
b. Broken connections between cells.
Fig. 4.112. — ^The Babcock electric roadster. This car is provided with a battery of forty two
cells, which it is claimed, gives one hundred miles at seventeen miles per hour on one
charge. The controller provides for five speeds forward and two reverse. The motor de-
velops fifteen horse power, which will run the car over thirty miles per hour.
c. Broken terminals.
d. Open motor leads.
«. Broken connections on any part of vehicle.
5. In case vehicle do not run on any of the speeds, first examine those
connections that are easiest to get at, viz:
a. Those at the end of the batteries.
fc. The connecting straps, connecting one cell to another.
c. The wires going into the circuit closing switch.
d. The springs on the controller arm and the copper shoes. Be sure that they
make contact with plates on the controller face.
e. See that there are no wires hanging loose, that appear to belong in the
controller.
/. If the trouble be not found in some one of these points, it would be best
to have an expert examine the machine. o
2,854 HAWKINS ELECTRICITY
1
6. If the usual graduation of speed be not obtained when runniQ
on the level, read carefully the instructions of maker relating to oontr 1 -
kr. ^^
7. If ammeter on the vehicle do not r^:ister properly, look u
the following:
a. Broken or partlv brokln connections in the wire leading from meter t
shunt block, under floor of carriage.
b. The ammeter pointer sticking or working irregularly, due to dirt ix^d
of ammeter, in which case it must go to the factory.
8. If the voltmeter do not register at all, look for broken connection
in wires leading to connection points tmder floor. »
9. If voltmeter read too high, there is something wrong inside; ij
should immediately be sent to the factory.
10. If the lights do not bum and the bell refuse to ring, look for i
burnt fuse wire.
11. If one light refuse to bum while the others are working correctb ,
try a new lamp, or examine connecting theater plug that connects b.
wiring to chassis wiring.
12. If both side lights refuse to bum, all other lamps being in workinj
order, the trouble is in the connector.
13. If bell refuse to ring, all lamps being in working order, examine
the theater plug connecting body and chassis wiring and make sure tha
the wires leading to the switch contacts at bottom of controller handl(
have not been taken out or broken off.
NOTE. — The bell can be tested by disconnecting from it the wires that an
there, connecting two temporary wires to these same binding posts and touching
these to the battery terminals. If the bell do not ring then it should be taken or
and replaced with a new one or readjusted.
NOTE. — No meter on an electric vehicle is infallible as the service is very
hard and the adjustments liable to ^et loose; and, as the general instructions as tc
care of battery, especially in charging, are to charge until voltage reads a certain
amount, it is of the highest imi)ortance that the meter should read correctly.
As soon as any irregularities are noticed in its readings, have it examined imme-l
diately by an expert, or send it to the factory. When it is necessary to return it
to the factory f be sure to send the shunt block with it, as this is part of the meter.,
Even if no irregularities be noticed it would be well to have the meter examined
at the factory and recalibrated once every year.
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rjELECTRICITY
IN HANDY POCKET FORM PRICE, $1 EACH
fromnetf They are not only the best, but the cheapest work published on
todirtiil Electricity, Each number being complete in itself. Separate numbers
sent postpaid to any address on receipt of price. Catalog of series
will be mailed free,
guide: No. 1 Treating on electrical signs and symbols — static and current
electricity — primary cells — conductors and insulators — resistance and conduc-
' iflsiae, tivity — effects of the current — magnetism — electro-magnetic induction — induc-
' tion coils— dynamo principles — classes of dynamo— field magnets — Armatures
— armature windings — ^armature theory— commutation and the commutator —
lookfoft brushes and the brush gear — ^armature construction.
GIJII^E: No* 2 Motor principles — ^armature reaction in motors — starting a motor
jL ' — motor calculations — ^brake horse power — selection and installation of dyna-
^ tBk "^^^ ^^^ motors — ^performance curves — location — foundation — belts — ^auxiliary
lectS 0. [bo machines — Galvanometer — standard cell s — current measurement — resistance
measurement-r-Christie bridge — testing sets — loop tests — potentiometer — arma-
ture voltmeter and wattmeter — multipliers — electro-dynamometers — demand in-
1 woriit dicators — ^watt hour meters — operation of dynamos — lubrication — troubles —
; coupling of dynamos — ^armature troubles — care of commutator and brushes —
! heating— operating of motors — starters — speed regulators.
exanjj guide: No. 3 Distribution systems — ^boosters — ^wires and wire calculations —
SUretl]} insidcj outside, and underground wiring — wiring of buildings — sign flashers —
,j.|jaD(U , lightning protection — storage battery — ^rectifiers — storage battery systems.
GUIDES No. 4 Alternating current principles — ^alternating current diagrams — the
power factor — alternator principles — alternator construction — ^alternator wind-
ings.
toucli^ GUIDES No* 6 Alternating current motors — synchronous and induction motor
tiieni- principles — construction of alternating current motors — ^A. C. commutator
t motors — ^power factor of induction motors — transformers — ^transformer losses —
transformer ^ construction — ^transformer connections — ^transformer tests — con-
verters — rectifiers — ^alternating current systems.
GUIDES No. 6 Transformation of phases — switching devices — circuit breakers
— relays — lightning projector apparatus — regulating devices — synchronous con-
densers — indicating devices — ^meters — power factor indicators — Wave form
measurement — switchboards.
GUIDE No. 7 Alternating current wiring — properties of copper wire power
stations — ^power station calculations — turbine practice — management — embrac-
ing: selection, location, erection, testi ng, running, care and repair — telephones.
guide: No. 8 Telegraph — simultaneous telegraphy and telephony— -wirelessr—
electric bells — electric lighting — ph otometry.
guide: No. 9 Electric railways — electric locomotives — car lighting— trolley car
operation — miscellaneous applications — motion pictures — gas engine ignition —
automobile self-st arters — ^and lighting systems — electric vehicles. ^^
guide: No. 10 Elevators — cranes — pumps — ^air compressors — electric heating* —
electric welding — soldering and brazing — ^industrial electrolysis — electro-plating
— electro-therapeutics, X-rays, etc. This number contains a complete ready
reference index of the complete library. ^^
Theo. Audel & Co«« Publishers* new york
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