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c,VTYO^

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^W^ci^

nuci

1Ji& AutomoDile
HAND-B OOK

WORK O" PR.
CAL JNtORMA
FOR THE USE

^^^^ Operators ^^^
Automobile MecKanics

RQAU TROUBLES
MOTOR TROUBLES
CARBURETER TROUBLES
IGNITION TROUBLES
CLUTCH TROUBLES
STARTING TROUBLES

By L. ELLIOTT BROOKES

FREDERICK J. DRAKE ^ CO.
PUBLISHERS CHICAGO

JransportatioQ
Wbrar^

FREDERICK J. DRAKE & COMPANY

CHICAGO, U. S. A.

// , - .' - -

The Automobile Hand-book

Accumulators — See Storage Batteries.

Acetylene. A number of inconveniences are
attached to the use of acetylene. The problem
of properly purifying it has yet to be solved.
Metallic compounds of sulphur, phosphorus and
nitrogen and free carbon are contained in the
carbide, and the gas has in it many impurities
which endanger health when burned in closed
rooms. The free carbon in the carbide gets into
the burners in the form of fine dust and obstructs
them. A great annoyance is smoking of the
lamps, which takes place after two or three
hours burning. This is due to decomposition of
the acetylene by the heated burner, by which
carbon is deposited in the narrow opening. Many
of the so-called spontaneous explosions of this gas
have without doubt been caused by high tempera-
ture in the generator — see also Gas Lamps.

Acid Solutions. The electrolyte, or solution
used in storage battery cells, is made by pouring
sulphuric acid into distilled water until the
specific gravity becomes 1.12. The solution
becomes extremely warm and should not be used
until its temperature is about 60 degrees,

8 THE AUTOMOBILE HAND-BOOK

A good soldering solution is made by neutraliz-
ing hydrochloric acid with zinc until it is no
longer strongly acid.

Admission-pipes, Diameter of. The internal

diameter of the admission or inlet-pipe leading
from the carbureter to the admission-valve cham-
ber should not exceed one-fourth the diameter
of the motor cylinder.

This limitation is necessaiy in order to produce
as great a partial vacuum as is possible in the
admission-pipe. The carbureter should be placed
as close as possible to the admission-valve
chamber of the motor in order to secure the best

results. Short turns or bends in the admission-
pipe greatly increase the air-friction in the pipe
and at high speeds greatly diminish the volume
of the charge drawn into the cylinder by the
' iductive or suction action of the motor-piston.

THE AUTOMOBILE HAND-BOOK

An admission-pipe with a side inlet and short
bends, for a two-eyhnder motor, is shown in
Figure 1. Such forms of construction should be
avoided whenever possible. Figure 2 shows an
admission-pipe of approved design, with long

bends, for a two-cylinder motor. The radius of
curvature of the pipe on its center line should not
be less than twice the outside diameter of the
pipe. If space allows, a radius of three times the
outside diameter of the pipe will give better results
than two diameters.

Admission-port — See Motor, Two-cycle.

Admission-valves, Diameter and Lift of.

For a motor of any desired bore and stroke and
speed in revolutions per minute, the following
formula may be used to determine the diameter
of the valve opening:

10 THE AUTOMOBILE HAND-BOOK

Let B be the bore of the motor cyh'nder in
inches, and S the stroke of the piston also in
inches. As R is the number of revolutions per
minute and D the required diameter of the valve
opening, then

BXSXR

15,000

Example: Required the diameter of the
admission-valve opening for a motor of 4|-inch
bore and stroke at 1,000 revolutions per
minute.

Answer: As 4^ multiplied by 4| and by 1,000
equals 20,250, then 20,250 divided by 15,000
gives 1.35 inches as the diameter of the valve
opening.

In practice, a motor of 4 J inches bore and
stroke has with a mechanically operated
admission-valve an opening of Ij inches diam-
eter and runs up to 1,200 revolutions per
minute.

The upper view in Figure 3 shows clearly the
diameter D referred to in the formula, as some
persons are in the habit of referring to the outside
diameter of the valve itself instead of the open-
ing in the admission-valve seat. The center
view in Figure 3 shows an admission- valve with
a flat seat, which is known as a mushroom valve,
on account of its shape. For this form of valve
to give a full opening the lift should be exactly

THE AUTOMOBILE HAND-BOOK

one-fourth of the diameter of the valve opening :
therefore if L be the required lift of the valve,
and D the diameter
of the valve opening,
then

L=- = 0.25 D
4

The lower view in
Figure 3 shows a valve
with a bevel seat, hav-
ing an angle of 45
degrees, which is most
commonly used. The
lift of this form of
valve requires to be
about three-eighths of

the diameter of the valve opening: that is, if L is
the required lift of the valve and D the diameter
of the valve opening, then

2.83

= 0.35 D

The bevel-seat form of valve is to be preferred
to the flat-seat or mushroom type of valve, for
two reasons: first, that it is more readily kept in
shape by regrinding, and second, it gives a freer
find more direct passage for the gases, as will be
])]ainly seen by reference to the lower view in
Figure 3.

12 THE AUTOMOBILE HAND-BOOK

Table No. 1 gives the correct diameter of valve
openings for motors from 3 by 3 to 6 by 6 inches
bore and stroke, with speeds from 900 to 1,800
revolutions per minute, and piston velocities of
600, 750 and 900 feet per minute, for mechanically
operated ad mission- valves.

Table No. 1.

Plstou Speail In Feet per Minute.

000

750

^ 1

,.i

^.1

s3o»

l§

0,72

1500

0-90

ISOO

1.08

1030

0.84

12S5

1.05

1570

1,26

900

0.96

1125

1.20

1350

1.44

^jf

800

i.oa

1000

1.35

1200

1.62

720

1.20

900

1.50

1080

1.80

S20

1.65

965

1.96

600

1.44

750

1.80

s«m

2.16

Atmospheric or suction operated admission-
valves require to be of .somewhat larger diameter
than mechanically operated ad mission- valves,
for two reasons: fir.st, that the incoming chaise
has to Hft the valve from its seat and keep it
suspended during the suction stroke of the motor
piston, and secondly on account of the resistance
offered by the valve spring, which tends at all

THE AUTOMOBILE HAND-BOOK

times to keep the valve on its seat. For an
atmospherically operated ad miss ion -valve which
will insure practically a full charge in tlie motor
cylinder the formula should be
BXSXR
12,750

The proper diameter for atmospherically
operated ad miss ion- valve openings may be readily
found by increas-
ing the required
diameter given in
the above table
for mechanically
operated admis-
sion-valves, by 15
per cent.

Example i What
should be the cor-
rect diameter for
the atmospheric-
ally operated ad-
mission-valve of a motor of 4j inches bore and
stroke, with a piston velocity of 750 feet per minute ?

Answer: Under the column headed 750 and
opposite 4^ by 4i, the diameter given is 1.35.
Then 15 per cent of 1.35 equals 0.80, which,
added to 1.35, gives 1.55 inches as the correct
diameter for the valve opening under the con-
ditions given — see also Valves.

THE AUTOMOBILE HAND-BOOK

Admission-valves, Forms of. Figures 4 and
5 are two fonns of combined admission-valve
and valve cage or
chamber. Figure
4 has the inlet on
top and Figure 5
on the side. Fig-
ures 6 and 7 show
two forms of de-
tachable or remov-
able admission-
valves. The one
shown in Figure 7
may be removed
from the motor

ADMISSION VALVE

wilhout disconnecting the admission-pipe,

screws into the combustion chamber and has

ings around the

lower portion for

the admission of the

explosive charge to

the valve.

Air. Air consists,
by weight, of oxy-
gen 77 parts and
nitrogen 23 parts;
by volume, of 21
parts oxygen and 79 parts nitrogen. One pound
of air occupies 13.8 cubic feet of space. One
cubic foot of air weiglu* 1 \ ounces.

ADMISSION VALVE

THE AUTOMOBILE HAND-BOOK

Air-cooled Motors— See Gasoline Motor
Construction.

Air, Properties of Compressed. The
accompanying table, which may be of use to
designers or builders of gas or gasoline motors,
gives the Mean pressure. Temperature in degrees
Fahrenheit, Gauge pressure, Absolute pressure
and the Isothermal or heat-pressure of air under
compression of from
1 to 6.10 atmos-
pheres.

As energy in the
form of power must
be used to compress
air to any desired
pressure, so is ener-
gy in the form of
latent or stored heat
given up by the air
during the operation
of compression.
This heat consequently increases the pressure
resulting from the compression, but not directly
in proportion to the degree of compression in
atmospheres.

This increase of pressure above the Adiabatic
or calculated pressure is known as the Isothermal
or heat-pressure. As the values of this pressure
cannot be calculated by the use of ordinary
mathematics, but involve the use of logarithms,

THE AUTOMOBILE HAND-BOOK

Table No. 2 gives these values for each degree of
compression given.

Table No. 2.
Properties of Compressed Air.

Ck)mp. in

■ciVff^An

Temp. In

♦Gauge

* A hiQol 11 1^

♦Isother-

Atmos-
pheres.

Pressure.

Degrees
Fah.

Pres-
sure.

Pressui'e.

mal Pres-
sure.

14.7

1.68

7.62

145

24.7

30.39

2.02

10.33

178

29.7

39.34

2.36

12.62

207

34.7

48.91

2.70

14.59

234

39.7

59.05

3.04

16.34

252

44.7

69.72

3.38

17.92

281

49.7

80.87

3.72

19.32

302

54.7

92.49

4.06

20.57

324

59.7

104 . 53

4.40

21.69

339

64.7

116.99

4.74

22.76

357

69.7

129.84

5.08

23.78

375

74.7

143.05

5.42

24.75

389

79.7

156.64

5.76

25.67

405

84.7

170.58

6.10

26.55

420

89.7

184.83

♦Inpou

nds per squ

are inch.

Many persons who are not familiar with the
properties of gases, estimate the pressure resulting
from the compression to a given number of atmos-
pheres, as the number of atmospheres multiplied
by the atmospheric pressure, which at sea level
is taken as 14.7 pounds per square inch.

This assumption is erroneous and will often
lead to grievous mistakes in motor design,
generally giving too much compression, which
results in premature ignition, commonly known

THE AUTOMOBILE HAND-BOOK 17

as backfiring. Such methods of calculation
would be true if the air, after compression, was
stored in a reservoir and allowed to cool, but
under no other conditions.

As the Isothermal pressures given in the table
are in absolute terms, to reduce them to gauge
pressure terms, 14.7 pounds must be deducted to
give the corresponding gauge pressure.

Air Resistance, Horsepower Required to

Overcome. The power required to move a
plane surface, such as the vertical projection of
an automobUe, against the air, does not become
of much importance until the car attains a speed
of 10 to 12 miles per hour, when it becomes an
important factor.

The horsepower required to propel an auto-
mobile against the resistance of the air may be
approximately calculated by the follov/ing formula.
Let V be the velocity of the car in feet per second,
and A the projected area of the front of the car
in square feet — this maybe assumed as the height
from the frame to the top of the body multiplied
by the width of the seat at the floor line of the
car — let H.P. be the horsepower required to over-
come the air resistance, then

VXA
H.P.=

240,000

To simplify the use of the above formula.
Table No. 3 gives speeds in miles per hour cor-

THE AUTOMOBILE HAND-BOOK

responding to their respective velocities in fed
per second and also cubes of velocities in fed
per second.

Table No. 3.

Cubes of Velocities in Feet per Second.

Miles i)er

Hour

of Car.

Feet per
Secoud.

Cube of

Velocity

In Feet per

Second.

Miles per

Hour of

Car.

Feet

per

Second.

Cube of

Velocity

In Feet per

Second.

10.2
13.6
17.2
20.4
27.2

15
20
25
30
40

3,375

8,000

15,625

27,000

64,000

34.0
40.9
47.7
54.4
61.3

50
60
70
80
90

125,000
216,000
343,000
512,000
729,000

To ascertain approximately the horsepower thai
will be necessary to drive a car against a wind d
known velocity, the speed of the car must be
added to that of the wind, and the required
horsepower may be found either by use of th(
formula given or by reference to Table No. 4
which gives the horsepower per square foot o:
projected surface required to propel a car agains
the resistance of the air, with varying speeds
in miles per hour or velocities in feet pei
minute.

The horsepower given by the formula anc
Table No. 4 simply refers to the additiona

power necessary to overcome air resistance anc

not to the actual power required to propel s
car at a given speed; this is entirely anothei
matter.

THE AUTOMOBILE HAND-BOOK

i Table No. 4.

i Horsepower Required per Square Foot op Sur-
face, TO Move a Car Against Air Resistance.

Horse-

Miles per

Feet per

power per

Miles per

Feet per

I)ower per

Hour

Square

Hour of

Square

of Car.

Second.

Foot of
Surf nee.

Car.

Secoud.

Foot of
Surface.

14.7

0.U13

58.7

0.84

22.0

0.44

73.3

1.64

24.6

0.105

87.9

2.83

36.7

0.205

117.3

6.72

44.0

0354

100

146.6

13.12

Tubes -See Tires.

Alcohol, Properties of. A carbureter designed
to operate with alcohol can always be used with
gasoline, but the reverse conditions are not true,
that is, a gasoline carbureter will not operate
successfully with alcohol, except in some rare
instances. Alcohol evaporates slower than gaso-
line and its time of combustion is much slower,
but it maintains its mean effective explosion
pressure far better than gasoline.

Explosive motors fitted with alcohol carbureters
make far less noise than when using gasoline as
a fuel, due to the slower burning of the explosive
charge, they also make less smoke and smell.

The jet or spray of a float-feed carbureter will
have to pass nearly 40 per cent more liquid fuel
than when using gasoline, consequently the open-
ing in the nozzle must be proportionally larger.

A carbureter using alcohol must be fitted with
some form of device to heat the alcohol to
ensure rapid evaporation — this is usually done

20 THE AUTOMOBILE HAND-BOOK

by surrounding the mixing-chamber with an
exhaust-heated jacket.

The same quantity of alcohol will only take a
car two-thirds of the distance that gasoline will,
hence greater storage capacity woulil be needed
on a car using alcohol as a fuel.

An explosive motor designed to use alcohol
requires a greater degree of compression than a
motor of the same bore and stroke designed to
use gasoline, in order to develop the same power.

Alloys, Composition of. The proper com-
position of alloys of metals for the bearings and
other parts of an automobile is a very important
consideration from a constructive standpoint.
Table No. 5 gives the composition of various
alloys of metals and also solders for different uses.
Table No. 5.
Composition or AlliOys.

i 6

nze, for Motor bearings. .

Bronze, for Axle beariuga . .

Brass, tor light work, other
tljan beariwgB ,

Bronze flanges, U) stand braz-
ing

Genuine Babbitt metal . .

Bronze, for bushings

Met:il to e.Ypaad in cooling, for
patterns

Genuine bronze

Solder, tor tin

Spelter, hard

Spelter, soft

THE AUTOMOBILE HAND-BOOK 21

Alternating Current, Use of. It is not only

useless but absolutely injurious to attempt to
charge a storage battery directly from an alter-
nating current circuit. This can only be done
by means of a rotary converter, which is in reality
a motor-generator, receiving its power from the
alternating current and transforming it into a
direct current which can be used to charge the
batteries.

Aluminoid, Composition and Use of. Alu-

minoid is composed by weight of 60 parts
aluminum, 30 parts tin and 10 parts zinc. It
has a tensile strength of about 18,000 pounds and
is a very suitable material for crank chambers,
gear cases and small brackets, being light,
extremely ductile and readily machined.

Aluminum Solder. The following formula is
for a solder which will work equally well with
aluminum or aluminoid: Tin, 10 parts —
cadmium, 10 parts — zinc, 10 parts — lead, 1 part.
The pieces to be soldered must be thoroughly
cleansed and then put in a bath of a strong
solution of hyposulphate of soda for about two
hours before soldering.

Ammeter, Construction of. Ammeters for

automobile use are constructed on the principle
of the D'Arsonval galvanometer with a permanent
magnetic field. The special feature is a small
oscillating coil mounted on cone-point bearings
surrounding a stationary armature which is

THE AUTOMOBILE HAND-BOOK

centrally located between the pole-pieces of a
permanent magnet,- with a pointer or index-finger
which indicates the electrical variations on a
graduated scale.

The construction of an ammeter is fully shown
in the two views in Figure 8, The permanent
magnets used in its construction are of a special

quality of hardened steel, made only for this
purpose and possessed of great magnetic per-
meability. The pole-pieces, which are of soft
steel and well annealed, are attached to the inside
of the lower part of the magnet legs, the joints
between the pole-pieces and the magnet legs are
usually ground to insure the full efficiency of the
magnetic circuit. The soft iron core of the coil

THE AUTOMOBILE HAND-BOOK 23

is for the purpose of rendering uniform the
magnetic field in which the coil has to oscillate.
A coil of insulated wire is wrapped upon the
i-tationary armature at right angles to its axis,
that is to say, in the same manner that thread is
wound upon a spool, which is short-circuited on
itself, that is to say, the ends of the wire fonning
the coil are fastened together. This coil of wire
is for the purpose of choking the magnetism
induced in the stationary armature by the oscillat-
ing coil, as it generates what are known as eddy
currents within itself, thus making the instru-
ment periodic, or dead-beat, in its indications.
Around the armature core and outside the short-
circuited coil of wire is wound the active or oscil-
lating coil and at right angles to the direction of
the winding of the first coil. The oscillating coil
consists of a number of turns of fine insulated
copper wire, to which the current is conveyed
through the medium of the controlling springs at
each end of the spindle, which is in two parts
and connected together by a suitable sleeve of
insulating material, as shown.

The pointer or index-finger is made with a
boss or hub to go over the end of the spindle of
the active coil and also has an extension with a
small counterweight or balance, so that the
pointer may be accurately adjusted.

The only difference in the construction of a
. voltmeter and an ammeter is that in the former

THE AUTOMOBILE HAND-BOOK

the active or oscillating coil is in series with a
high resistance, while in the latter it is connected
across the terminals of a shunt-block. The
voltmeter is in reality an ammeter, the resistance
serving to keep the amperage in step with the
voltage.

Reference to the three views, marked respect -
ively A, B and C in Figure 9, will show clearly
the principle of the operation of an ammeter or

voltmeter and the reason that they record the
current strength or pressure of an electric
current accurately.

Ammeters are of two kinds, the double-beat
type, as shown in Figure 8, which indicates the
current strength or number of amperes flowing in
the electric circuit, without any regard to the
polarity of the terminals of the circuit, by the
pointer or index-finger moving either to the right
or to the left of the zero position. The single-

THE AUTOMOBILE HAND-BOOK

beat type of ammeter only records in one direc-
tion, by the pointer moving from the left to the
right of the graduated scale of the instrument,
consequently the polarity of the terminals of this
type of ammeter are marked on its outer casing
and the polarity of the terminals of the electric
circuit must consequently be determined before
connecting them with the ammeter.

VOLTS

AMPERES

VOLT- AM METER

Fig. 10

A volt-ammeter, such as is commonly used on
electric automobiles, is shown in Figure 10.
This instrument is simply a voltmeter and a
double-beat ammeter mounted on a single base
and enclosed in a common case, with their
graduated scales adjoining each other.

Ampere — See Electrical Rules and Formulas.

Ampere-hour, Definition of. The term
ampere-hour is used to denote the capacity of a

26 THE AUTOMOBILE HAND-BOOK

storage or a closed -circuit primary battery for cur-
rent. A storage battery that will keep a 2 ampere
lamp burning for 8 hours is said to have a 16
ampere-hour capacity. In a similar manner an 80
ampere-hour battery would operate the same lamp
40 hours. The voltage of a battery does not en-
ter into the calculation of its ampere-hour capac-
ity-
Angle Iron — See Structural Shapes.

Animal Power, Capacity of. A man can

exert a pull of 30 pounds, for 10 hours a day,
with a speed of 1.70 miles per hour.

A man carrying a load a short distance and
returning unloaded, can carry 135 pounds 6 miles
in a day. He can also carry 120 pounds 8 miles
in a day — or push in a wheelbarrow 150 pounds
10 miles as a day's work.

A man can walk on a smooth, level road for
8i hours at the rate of 3.67 miles per hour.

A horse can travel 400 yards : at a walk, in 4^
minutes — at a trot, in 2 minutes — at a gallop, in
1 minute.

A work-horse, on a good road, can pull 1,600
pounds 23 miles in a day, weight of vehicle
included.

A good horse, in the best of condition, can only
exert his full capacity, or one horsepower, for 6
hours per day.

The work of one horse is approximately equal
to th^t of five men.

THE AUTOMOBILE HAND-BOOK 27

Anti-freezing Solutions. To prevent the

water in the jacket of a gasoline motor from
freezing during cold weather, calcium-chloride
or glycerine may be used. The calcium-chloride
should be dissolved in hot water in the proportion
of 4 pounds of calcium-chloride to 1 gallon of
water. Allow the solution to stand until fully
settled, then carefully draw off the liquid without
disturbing the sediment.

Glycerine in the proportion of 2 pints to 3 pints
of water may also be used for the same purpose,
but is much more expensive than the calcium-
chloride.

Neither of these solutions will stand a twenty
degree below zero temperature.

Areas and Circumferences of Circles — See

Table No. 6.

Armatures, Slotted and Shuttle Types of.

An armature is the rotating part of a dynamo or
electric motor which generates electricity or
develops power.

The armature shown in Figure 11 is known as
the Siemen's H or shuttle type and is the simplest
form of wire-wound armature known. The
current given by this form of armature is of the
alternating type and is converted into a direct-
current, when desired, by means of a two-part
commutator on the armature shaft.

The slotted type of armature shown in Figure
12 has a more intricate system of winding than

THE AUTOMOBILE HAND-BOOK

Table No. 6.

Areas and Circumferences of Circles from 0.05 to
10.0, Advancing by ^^o of one inch.

Diam.

Area

Circum.

Diam.

Area

Circum .

.05

.0019

.16

2.05

3.30

6.44

.10

.0078

.31

2.10

3.46

6.59

.15

.017

.47

2.15

3.63

6.75

.20

.031

.63

2.20

3.80

6.91

.25

.049

.78

2.25

3.98

7.07

.30

.070

.94

2.30

4.15

7.22

.35

.096

1.09

2.35

4.34

7.38

.40

.12

1.26

2.40

4.52

7.54

.45

.16

1.41

2.45

4.71

7.69

.50

.19

1.57

2.50

4.91

7.85

.55

.24

1.73

2.55

5.11

8.01

.60

.28

1.88

2.60

5.31

8.17

.65

.33

2.04

2.65

5.56

8.32

.70

.38

2.19

2.70

5.72

8.48

.75

.44

2.36

2.75

5.94

8.64

.80

.50

2.51

2.80

6.16

8.79

.85

.57

2.67

2.85

6.38

8.95

.90

.64

2.83

2.90

6.60

9.11

.95

.71

2.98

2.95

6.83

9.27

1.00

.78

3.14

3.00

7.07

9.42

1.05

.86

3.29

3.05

7.31

9.58

1.10

.95

3.46

3.10

7.55

9.74

1.15

1.03

3.61

3.15

7.79

9.89

1.20

1.13

3.77

3.20

8.04

10.05

1.25

1.23

3.93

3.25

8.29

10.21

1.30

1.33

4.08

3.30

8.55

10.37

1.35

1.43

4.24

3.35

8.81

10.52

1.40

1.54

4.39

3.40

9.08

10.68

1.45

1.65

4.56

3.45

9.35

10.84

1.50

1.77

4.71

3.50

9.62

10.99

1.55

1.89

4.87

3.55

9.89

11.15

1.60

2.01

5.03

3.60

10.18

11.31

1.65

2.14

5.18

3.65

10.46

11.47

1.70

2.27

5.34

3.70

10.75

11.62

1.75

2.40

5.49

3.75

11.04

11.78

1.80

2.54

5.65

3.80

11.34

11.94

1.85

2.69

5.81

3.85

11.64

12.09

1.90

2.84

5.97

3.90

11.94

12.25

1.95

2.99

6.13

3.95

12.25

12.41

2.00

3.14

6.28

4.00

12.57

THE AUTOMOBILE HAND-BOOK

Table No. 6— Con

'nued.

Dlam, Area

ClrcuiD,

Dl.m,

Are.

Clruura.

4.05

12.88

12,72

6.25

30-68

19.63

4,10

13,20

12.88

6-30

31.17

19.79

4.15

13.53

13.04

6.35

31.67

19.95

4.21)

13.85

13 19

6-40

32,17

20,11

4.25

14.19

13 35

6 45

32-67

20-26

4.30

14.52

13 5!

6,50

33.18

20-42

4.35

14.86

13,60

6 65

33.69

20,58

4.40

15,20

13,82

6.60

34,21

20-73

4.45

15.55

13.98

6.65

34.73

20-89

4.50

15.90

14.14

6,70

35.26

21-06

4.55

16,25

14,29

6,76

35.78

21-20

4,60

16 62

14.46

6,80

36,32

21.36

4,85

16, 9S

14,61

6.85

36.85

21.52

4,70

17.35

14,76

6. BO

37.39

21 68

4,75

17.73

14.92

6,95

37,94

21.83

4.80

18,09

15.08

7,00

38.48

21 99

4,85

18,47

15.24

7.05

39.04

23.15

4,90

18.86

15.39

7.10

39,59

22.30

4.95

19,24

15.55

7,15

40.15

22.46

5,00

19,63

15,71

7.20

40.71

22.62

5,06

20.03

15.86

7.25

41,28

22.78

5.10

20.43

16,02

7,30

41.85

22.93

5,15

20,84

16.18

7.35

42.43

23,09

5.20

21.23

16.34

7.40

43.01

23.25

5,25

21,65

16.49

7.45

43.59

23.40

5,30

22,06

16.66

7.50

44.18

23,56

5-35

22 48

16.81

7 55

44.77

23.72

5,40

22,90

16,96

7.60

45 36

23.88

5,45

23,33

17.12

7,65

45.96

24.03

S.30

23.76

17.28

7.70

46.57

24.19

5.55

24,19

17.44

7.75

47.17

24.35

5.60

24,63

17.59

7.80

47,78

24.50

5.65

25.07

17,75

7,85

48.39

24.66

5,70

25 52

17.91

7.90

49.02

24,82

5.75

25.97

IS. 06

7.96

49.64

24.97

5.80

26.42

18.22

8.00

50.26

25.13

5.85

26,88

18.38

S.05

50.89

25,29

5.1)0

27.34

18,54

8,10

51.53

25.43

5.95

27.80

18.69

8.16

52.17

25.60

6,00

28.27

18.85

8.20

52,81

25,76

6.05

28.73

19.01

8-25

53.46

26.92

6,10

29.22

19 16

8.30

54 11

26,07

6 15

29.70

19 32

8.35

54,76

26.23

6.20

30.19

19.48

S-40

65.42

26,39

THE AUTOMOBILE HAND-BOOK

Table No. 6. — Continued.

Diam.

Area

Circum.

Diam.

Area

Circum.

8.45

56.08

26.55

9.25

67.20

29.06

8.50

56.74

26.70

9.30

67.93

29.22

8.55

57.41

26.86

9.35

68.66

29.37

8.60

58.09

27.02

9.40

69.39

29.53

8.65

58.76

27.17

9.45

70.14

29.69

8.70

59.45

27.33

9.50

70.88

29.84

8.75

60.13

27.49

9.55

71.63

30.00

8.80

60.82

27.65

9.60

72.38

30.15

8.85

61.51

27.80

9.65

73.14

30.32

8.90

62.21

27.96

9.70

73.89

30.47

8.95

62.91

28.12

9.75

74.66

30.63

9.00

63.62

28.27

9.80

75.43

30.79

9.05

64.33

28.43

9.85

76.20

30.94

9.10

65.04

28.59

9.90

76.98

31.10

9.15

65.76

28.74

9.95

77.76

31.26

9.20

66.48

28.90

10.00

78.56

31.42

To compute the area or circumference of a diameter greater

than 10 and less than 100:

Take out the area or circumference from table as
though the number had one decimal, and move the
decimal point two places to the right for the area, and
one place for the circumference.

EXAMPLE — Wanted the area and circumference of
56.5. The tabular area for 5.65 is 25.07, and circum-
ference 17.75. Therefore area for 56.5=2507 and cir-
cumference= 177.5.
To compute the area or circumference of a diameter greater

than 100:

Divide by a factor, as 2, 3, 4, 5, etc., if practicable, that
will leave a quotient to be found in table, then multiply
the tabular area of the quotient by the squaxe of the
factor, or the tabular circumference by the factor.

EXAMPLE — Wanted the area and circumference of
47.5. Dividing by 5, the quotient is 9.5, for which the
area is 70.88, and the circumference 29.84. There-
fore area of 70.88X25 = 1772 and circumference=
29.84X5=149.2.

THE AUTOMOBILE HAND-BOOK

the shuttle type just described. It has, however,
a far greater electrical efficiency and gives off a
steadier current than the shuttle type. It is the
form most generally used for automobile and
street railway motors. Like the shuttle type of
armature, the current generated by the slotted
type of armature is alternating and is con-
verted into a direct-cur-
rent by means of a
commutator of very
complicated form — see
Electric Motors.

Asbestos — See Insu-
lating Material.

Automobiles, Typi-
cal American. Gaso-
line. A — Runabout.
B — Touring car. C —
Light car with detach-
able Tonneau. D —
Stanhope. E — Road-
ster.

Electric. F — Runabout. G — Park trap. H —
Phaeton. J — Brougham. K — Depot-bus or
light delivery wagon. See first page for drawing.

Axles, Front and Rear. So far it has not

been found practical to combine the steering and
tractive functions of an automobile in one set of
wheels and axle, it is necessary to use a rigid
front axle with knuckle- jointed spindles and

THE AUTOMOBILE HAND-BOOK

utilize the tractive power of the rear wheels only
to propel the car. Some of the earlier forms of
steering axles had the wheel pivots inclined so as
to bring the projection of the pivot axis in line
with the point of contact of the wheel with the
ground, but as such constructions have not proved

satisfactory they have in most cases been aban-
doned.

Front Axles. Figures 13 and 14 show four
styles of front axles with steering-pivot ends : A
shows a solid axle of square section, with the
steering-pivot jaws and axle proper, of a single
forging — B represents an axle of tubular cross-

THE AUTOMOBILE HAND-BOOK

section with the steering-pivot jaws bored out to
receive the tubular axle which is firmly brazed
therein— C shows another style of tubular axle,
in which the steering-pivot jaw ends are turned
down to fit the inside diameter of the tube and
are also brazed in position, while D illustrates a

one-piece axle with vertical hubs instead of jaws,
which carry L-shaped steering-pivots, instead of
the usual form of knuckles.

Reah Axles. A great many medium and
high-powered cars have a double side-chain drive;
this necessitates free driving wheels and a rigid
rear axle with this form of drive.

THE AUTOMOBILE HAND-BOOK

Figure 15 illustrates three forms of rigid rear
axles for the above described form of drive: E
shows a solid axle of circular section with straight
spindles for hubs with plain-bearings — F, a
solid axle of square section with taper spindles
for plain-bearing hubs and G an axle of tubular
section with spindles fitted for ball-bearing hubs.

REAR AXLES

Fig 15

Automobiles employing a single chain drive
from the motor to the rear axle, generally use
either a live solid rear axle with one driving
wheel earned upon a loose sleeve attached to one
of the gears of the differential, or a rigid tubular
axle with a divided live-shaft, to the outer ends
of which the driving wheels are keyed. Axles of
these types are shown in Figure 16 : H illustrates

THR AUTOMOBILE HAND-BOOK 35

,!&,

p. I — ^ n

36 THE AUTOMOBILE HAND-BOOK

a solid live rear axle with plain-bearings and
sprocket on the differential gear case.

Normally both the axle and the sleeve rotate in
unionism, but on the car departing from a
straight course or turning a comer, the sleeve
will move faster or slower than the axle, accord-
ing to the direction of curvature. A rigid tubular
axle with a divided live driving shaft is shown at
J; the tubular portions of the axle have spiders
on their inner ends, which are connected around
the differential gear and sprocket by means of
shoulder-studs with nuts, as shown in the draw-
ing. The type of axle illustrated at H may have
either plain or roller-bearings, while the type
shown at J is usually constructed with four sets
of ball-bearings, two sets at the outer ends of
the tubular axle and two sets near the center,
one on either side of the differential case, within
the hubs of the spiders.

In Figure 17, K and L show respectively a
live solid rear axle and a rigid tubular axle,
equipped with roller-bearings. The spring lugs
form part of the roller-bearing boxes of the live
axle, while they are usually brazed to the tubular
axle near its outer ends.

A rigid tubular axle with ball-bearing live
driving shaft is illustrated in Figure 18, the ball-
cup or race is adjustable by means of a hexagon
upon its outer extension in the rear of the hub of
the wheel and is held securely in position and

THE AUTOMOBILE HAND-BOOK

prevented from turning by means of the clamping
device shown on the upper portion of the bear-
ing. No separate adjustments for the inner two
sets of ball-bearings are necessary, as the teeth
of the spur gears of the differential which are
keyed to the inner ends of the divided driving
shaft, being free to slide upon themselves, allow
the shafts M to have a slight longitudinal move-
ment within the axle tube, thus taking up the

BALL BEARING AXLE

Fig. 18

wear of each pair of ball-bearings with a single
adjusting mechanism.

Steering Knuckles. In order to obtain
ease of operation and secure the shortest turning
radius with the least movement of the steering
wheel or lever, the knuckle of the steering pivot
should be as close to the center of the wheel as
is possible. It is ako of great importance that

THE AUTOMOBILE HAND-BOOK

Fig. 19

uitJ

STEERING KNUCKLE

40 THE AUTOMOBILE HAND-BOOK

the steering knuckles should be as heavy as is
practically consistent with the size and weight of
the car for which they are intended. If this
important point be neglected, rapid wear and
probable fracture of the knuckles may be looked
for.

The earliest form of steering knuckle for a
pivoted axle was invented by Lankensperger of
Munich in 1819, since that time but little change
has been made in the basic principle of the
pivoted axle.

Steering knuckles at present in use consist of
two principal types: a spindle and pivot of T
shape and an axle with jaw ends — a spindle and
pivot of L shape and an axle with vertical hubs.

A steering knuckle with a spindle and pivot of
T shape is shown in Figure 19. The spindle
and pivot N and the steering arms O are usually
a one-piece forging. The steering arms O are
connected by means of a suitable distance rod
and the steering lever P is attached to one of the
pivots N by turning a shoulder upon it and pin-
ning and brazing the steering lever and pivot hub
together.

Figure 20 shows a steering knuckle with spindle
and pivot of L shape. The steering arm R goes
on the lower end of one pivot Q only, the other
pivot having the combined steering arm and lever
S on its lower end. The steering arms being
detachable, the device may be operated from the

THE AUTOMOBILE HAND-BOOK 41

iQi

Fks. 20

r^ — ^^

3_^

IQJ

7~~=

I I
I I

STEERING KNUCKLE

42 THE AUTOMOBILE HAND-BOOK

right or left hand side by simply exchanging the
levers R and S. The steering lever S has a ball
upon its outer end to fit in the socket on the
connecting rod of the steering mechanism.

Backfiring, Causes of. Tliis is a term

applied to an explosion or impulse which forces
the flywheel of a motor suddenly backwards, that
is, in the opposite direction to its proper rotation.
The term is sometimes used in connection with
explosions which occur in the muffler from the
ignition of an accumulation of unbumed gases.

Causes. An overheated combustion chamber,
due to a poor circulation of the cooling water —
causing self-ignition of the charge before the
proper time.

Advancing the ignition point too far ahead
when the motor is running slowly under a heavy
load — flywheel has not sufficient momentum to
force the piston over the dead center, against the
pressure of the already ignited and expanding
gases.

The presence of a deposit of carbon (sootj or
a small projecting surface in the combustion
chamber which may become incandescent and
cause premature ignition — see also Starting
Troubles.

Ball and Socket Joints. To produce a

flexible joint capable of operation within certain
limitations in any direction, the ball and socket
form of joint is generally used on the ends of

THE AUTOMOBILE HAND-BOOK

the rod whith connefts the arm of the steering

mechanism with the steering lever attached to the

hub of one of the steering pivots of the front axle.

Figure 21 shows a form of ball-joint used on

several makes of cars. The steering lever B has

a ball on its outer end,

which is held in the

socket A by means of

a threaded bushing as

shown in the drawing.

This bushing can be

adjusted to take up all

lost motion or wear of

the working parts and

is held from turning by

means of the clamping

device shown at * the

upper end of the socket

A. The arm of the

steering mechanism is pi-ovided with a stud C

having a ball similar to tlie one on the end of the

steering lever II, which also fits into a socket A.

The two sockets are suitably connected by means

of a rod.

Ball-bearing Axles— See Axles.

Ball-bearing Hubs— See Hubs.

Band-brakes— Sec Brakes

Battery Charging Outfit. A four or six volt
storage battery used fori;^nilion purposes may be
chained very simply in the following manner:

44 THE AUTOMOBILE HAND-BOOK

Use ten cells of gravity battery. They are low
in first cost and inexpensive to recharge. Sul-
phate of copper, commonly known as blue stone
or blue vitrol and water, is all that is needed to
charge the cells, no acids being used. When not
in use, put on a closed circuit with a resistance
coil of about 150 to 200 ohms, as otherwise a
slight local action takes place when the cells are
not in use — see Batteries, Dry and Primary,
also Storage Battery Charging.

Batteries, Dry and Primary. To ascertain

the internal resistance of a dry or primary
battery, proceed as follows: With a suitable
voltmeter, obtain the voltage of the battery at its
terminals when on open circuit. With a known
resistance in the battery circuit — say 100 feet of
No. 10 B. & S. Gauge copper wire — again obtain
the voltage of the battery, also note the amperage
with an ammeter; this, however, must be done
quickly before polarization occurs.

Let V be the voltage of the battery at its
terminals when on open circuit, and v the voltage
of "the battery with a known resistance in the
circuit, let C be the current in amperes flowing
through the known resistance and R the required
internal resistance of the dry or primary battery,
then

T. V — V

To demonstrate the truth of the above formula

THE AUTOMOBILE HAND-BOOK 45

and also to prove the correctness of the instru-
ments used in making the test, when the value
of the internal resistance R has been ascertained,
then C, the current flowing with a known resist-
ance in the battery circuit, should equal in value
the result of the formula given below, which is

^ R

Dry Batteries. In one respect dry batteries
have a decided advantage over storage batteries
for ignition purposes, from the fact that on
account of their high internal resistance they
cannot be so quickly deteriorated by short
circuiting.

On account of this high internal resistance,
diy batteries will not give so large a volume of
current as storage batteries, but a set of dry
batteries may be short circuited for five minutes
without apparent injury and will recuperate in
from twenty to thirty minutes, while a storage
battery would in all probabiUty be ruined under
the same conditions.

If dry batteries only are used for ignition pur-
poses, two sets should be carried, of not less than
6 cells each, connected with a two-point switch.
One set of batteries should be used not to exceed
thirty minutes and then the other set switched
on. In this manner the batteries will have a
much longer life than if used continuously — see
Diagram, Wiring for a Single Cylinder Motor,

46 THE AUTOMOBILE HAND-BOOK

A dry battery of the .usual type consists of a
zinc cell which forms the negative element of the
battery. The electrolyte is generally a jelly-like
compound containing sal-ammoniac, cliloride of.
zinc, etc. The carbon or positive element is
enclosed in a sack or bag containing dioxide of
manganese and crushed coke, which are the
depolarizing agents of the battery.

Dry batteries which have become exhausted
may in most cases be recuperated in the following
manner: First disconnect the cells from each
other and remove their pasteboard covers, then
drill a hole in the sealing compound on top of the
cell, about one-quarter of an inch in diameter
and at least 2 inches in depth so as to insure
getting below the sealing compound. Take 1
ounce of bisulphate of mercury and put in a
porcelain or earthenware vessel (on no account
use a metal vessel) and pour over it one-half pint
of boiling water — when cold, draw, off the clear
solution, being careful not to disturb the yellow
precipitate left at the bottom of the vessel, which
is useless and should be thrown away at once,
as it is a rank poison. Dissolve 4 ounces of
sal-ammoniac in 1 pint of hot water and when
cold mix with the first solution and the recuper-
ative agent is then ready for use. Take a small
glass funnel, or a tin one that is thoroughly
painted or enameled, and introduce about a
tablespoonful of the liquid into each cell through

THE AUTOMOBILE HAND-BOOK 47

the hole already drilled for this purpose. The
liquid must be introduced into the cells very
slowly, as it will take a long time to absorb, and
the cells should be allowed to stand at least 12
hours after filling before being ready for use.

Primary Batteries. When there is no
incandescent light circuit at hand or the electric
current is of the alternating type, primary batteries
of some form or other are very useful to charge
small storage batteries which are used for ignition
purposes.

The voltage of a set of primary batteries to be
used for charging a small storage battery, should
exc eed the voltage of the storage battery by at
least 30 per cent.

Primary batteries of the open -circuit type, such
as sal-ammoniac cells, are useless for charging
purposes, only batteries of the closed-circuit or
constant current type are suitable.

A very simple and inexpensive form of closed-
circuit battery for charging purposes is the single
liquid type, which uses zinc and carbon electrodes
in a 20 per cent solution of sulphuric acid and
water, with nitrate of soda as the depolarizing
agent.

For a 4 volt storage battery four such cells are
required, while for a 6 volt storage battery six
cells will be necessary for a proper charge.

This form of primary battery has a voltage of
li volts per cell.

48 THE AUTOMOBILE HAND-BOOK

The articles necessary for a complete charging
outfit are as follows : One small pocket ammeter
reading up to 5 amperes, one two-point switch,
one resistance coil or rheostat (home made), one
set of closed-circuit type of primary batteries and
about 25 feet of No. 16 B. & S. Gauge, Okonite
or Kerite stranded copper wire for the connections.

The method of connecting the primary batteries,
resistance coil (rheostat), ammeter and switch is
plainly shown in Wiring Diagram No. 1. The
positive pole of the primary battery should always
be connected with the positive pole of the storage
battery, the carbon element is always the positive
electrode in both dry and primary forms of
batteries. If the polarity of the terminals of the
storage battery are not indicated on the case by
the + and — signs, which represent positive and
negative respectively, their polarity may be
readily ascertained by means of a piece of
moistened litmus paper (paper soaked in a
solution of iodide of starch). Place the piece of
moistened litmus paper on a board or other non-
conducting material and bring the wires from the
storage battery terminals into contact with
opposite ends of the paper for a few seconds
only — one end of the paper will turn red, this
will be next to the wire connected with the
negative pole of the storage battery.

The resistance coil or rheostat may be made
very simply as follows: Take a piece of hard-

THE AUTOMOBILE HANU-BOOK

50 THE AUTOMOHILK HA\D-B()()K

wood 3 inches s(|iiare and 1.5 inches long and turn
down about IS J inches of its length to a diameie"
of 2^ inches in the manner shown. Upon this
turned part cut with a round -nose tool a groove
or thread one-sixteenth of an inch deep, with 8
threads to the inch. In this groove wind about
50 feet of No. 18 B. W. Gauge bare soft iron
wire and connect with a bar and sliding contact
as shown in the drawing.

To charge the storage battery, move the sliding-
contact to the right until all the resistance is in
use, then move the switch-finger to the point on
the left and adjust the sliding-contact by moving
it to the left until the ammeter shows 3 amperes.
Moving the switch-finger to the right will put the
battery in the circuit for charging and the sliding-
contact should be again adjusted until the
ammeter shows 3 amperes. The sliding-contact
should be adjusted from time to time to keep the
charging current at 3 amperes.

If the storage battery be of 12 ampere-hour
capacity it will take 4 hours to properly charge it,
if of 18 ampere-hour capacity, 6 hours. The
ampere-hour capacity of the battery divided by
the amperes of the charging current gives the
number of hours required to fully charge the
battery when exhausted.

After the storage battery is fully charged the
electrodes should be lifted out of the solution as
shown in the drawing, by means of the cover to

THE AUTOMOBILE HAND-BOOK 51

which they are shown attached, until the battery
is again required for use.

Battery Syringe, Use of. Battery syringes

are made in two forms. One form of hard rubber
with a sUding piston, the other of soft or flexible
rubber in the shape of a bulb to be operated by
pressure of the hand.

Either form of battery syringe is used to with-
draw a portion of the electrolyte or solution
from a storage battery cell for the purpose of
afterwards testing its density and specific gravity.

Battery Troubles, Causes of. The following

are some of the troubles which may occur to a
battery :

Loose or corroded terminals will cause a poor
electrical contact and failure of the battery to
work properly — Remove all thumb-nuts from the
binding-posts and clean their contact surfaces
thoroughly with emery cloth and screw up firmly
after replacing.

Broken wires, or the insulation being worn off
some part of the wiring of the car, causing a
short-circuit by contact with the metal of the
frame — The wires should be disconnected from
the battery, and the battery tested across its
terminals with an ammeter — If the battery is in
good condition, reconnect one wire only to the
battery and with an extra piece of wire attached
to the other battery terminal, test the coil, com-
mutator and switch connections to locate the

52 THE AUTOMOBILE HAND-BOOK

break and around the metal of the frame for the
short-circuit; if not found, reverse the wires and
proceed as before. In this manner the break or
short-circuit must .eventually be discovered.

Weak or run-down batteries cause a motor to
misfire and run irregularly — A new set of cells
should be used to test the motor with; if it stiD
misfires the trouble must be looked for elsewhere.

Dry batteries will show practically their fuD
voltage when almost exhausted — A small pocket
ammeter should be used to test each cell with.
If any of the cells show less than 5 or 6 amperes
they should be at once discarded.

Dry batteries polarize very quickly if left on a
closed circuit for a few minutes. This is generally
caused by the operator of the car omitting to
open the switch, when the motor has stopped for
some reason or other — If allowed to rest for 20
to 30 minutes, they will generally recuperate suffi-
ciently to enable the operator to start the motor.

Dry batteries will also polarize from too rapid
working or too long use without a rest — Two sets
of batteries should always be carried on a car and
one set at a time used for about 30 minutes, the
other set then being used for another 30 minutes.
This method will not only give more satisfactory
results than by using a single set, but will pro-
long the life of the batteries.

A dead or exhausted cell in a set of dry
batteries will prevent the rest of the cells from

THE AUTOMOBILE HAND-BOOK 53

working properly — With a small pocket an, neter
test the amperage of each cell separately until the
dead cell is found — Remove the dead cell and
substitute a new one in its place if possible, if
not, cut the dead cell out of the battery circuit.

The amperage of a dry battery when new is
about 12 to 15 amperes on a closed circuit.
When an ammeter only shows 5 or 6 amperes,
the cell is practically exhausted and should be
replaced by a new one.

The voltage of a storage battery should never
be allowed to fall below 1.75 volts per cell. This
applies to each individual cell and not a set of
cells in one case.

When fully charged a storage battery should
show 2.2 volts per cell.

A storage battery should never be allowed to
remain in a discharged condition over twelve hours.

Never test or experiment with a storage battery
by short-circuiting it across its terminals by
means of a piece of wire, an old file or a screw-
driver.

Troubles with storage batteries, resulting from
fiulure to comply with the above conditions, can
only be remedied by the makers.

Bearings, Plain, Ball and Roller. Plain

bearings are as a rule in general use for thv
motors and speed-change gears of gasoline cars,
and some makers prefer to use them on the road
wheels as well, on account of their simplicity.

54 THE AUTOMOBILE HAND-BOOK

ease of renewal when worn and practically inex-
pensive construction.

Ball-bearings are also used on the armature
shafts of electric automobile motors and in the
hubs of the front and rear wheels of different
makes of cars. Gars equipped with rigid tubular
rear axles usually have the live driving shaft
fitted with ball-bearings.

Live rear axles are either plain or roller-bear-
ing, as their construction usually renders the use
of ball-bearings impracticable.

Plain - BEARINGS. For plain -bearings, the
shafts of which are continuously running at a
high rate of speed, such as motors and speed -
change gears, the working pressure per square
inch should not exceed 400 pounds. As the arc
of contact or actual bearing surface of a journal-
bearing is assumed as one-third of the circum-
ference of the journal itself, the pressure per
square inch upon a bearing is therefore equal to
the total load upon the bearing, divided by the
product of the diameter of the journal into the
length of the bearing.

I^t D be the diameter of the journal or shaft
at its bearing, and L the length of the bearing.
if W be the total load or pressure upon the bear-
ing and P the pressure in pounds per square incli
of bearing surface, then

DxL

THE AUTOMOBILE HAND-BOOK 55

If the total load or pressure on the bearing be
known and the diameter of the shaft given, then
the proper length of the bearing will be

L= ^^-
DXP

If the length of the bearing be known and
other conditions as before given, then the proper
diameter of the journal will be

PXL

The length of a plain-bearing should not be
less than the following proportions:

One and one-third diameters for crank-shaft
wrist-pin bearings.

Two diameters for crank -shaft bearings.

Two and one-half diameters for speed-change
gears.

Three diameters for live rear axles.

Four diameters for wheel hub bearings.

Ball-bearings. The friction of a well de-
signed ball-bearing varies directly witli the load
and is entirely independent of the speed. The
starting friction of ball-bearings is far less than
the best lubricated plain -bearing.

While ball-bearings give less rolling friction
than plain-bearings, at their best they still involve
a considerable loss of power, due to the fact that
they roll in opposite directions and consequently
rub against each other, with the result that the

THE AUTOMOBILE HAND-BOOK

balls soon wear out, in addition to the power
losses by friction.

For automobile use the ball-races should have
rounded grooves and be also ground perfectly true.

Table No. 7 gives the safe working load for
steel balls of varying diameters. It must be con-
sidered in this connection that the working load
is carried by one ball at a time.

Table No. 7.
Safe Working Load of Steel Balls.

Diameter of ball.

500

780

1125

1530

i
2000

ft
2530

f
3125

Working load per
ball in pounds.

Roller-bearings . The amount of power that
may be saved by the use of roller-bearings is con-
siderable and the only obstacle to their more
general use is the difficulty of obtaining a bearing
of simple form which may be easily adjusted in
case of wear.

Roller-bearings of parallel form being incapable
of adjustment, this objection has been in part
overcome by the use of rollers of conical form,
which in some cases are designed to also take up
the end thrust which occurs in automobile use.

The usual method of mounting rollers for

bearings is to enclose them in a suitable form of

cage, in which the rollers are se^axaV^, ^o that

THE AUTOMOBILE HAND-BOOK 57

58 THE AUTOMOBILE HAND-BOOK

when rotating on their axes the rollers do not
come into contact with each other. In some
forms of roller-bearings it is considered good
practice to include end thrust ball-bearings at the
outer ends of the roller cages, so as to still
further reduce the friction incident to the rotation
of the roller cages.

Binding Posts — See Terminals.

Bodies, Styles of. The automobile bodies
illustrated in Figures 22 and 23 are reproduced
from dimensions taken from bodies of cars in
actual use and are simply given to show what
has been accomplished in the design of automo-
bile bodies at the present state of the industry.

Bodies for cars with vertical motor in front,

under a hood or bonnet.

A — For touring car with four-cylinder motor —

provision for tonneau in rear.

B — Runabout body for car with two-cylinder
motor — space for baggage basket at the rear.

C — Body for light touring car with baggage
box in the rear of the body.

I) — For light runabout car — space for extra
tire and tools in the rear of the body.

Bodies for cars with horizontal motor under-
neath the body proper.

E — Runabout body with tool and battery box
in front — provision for tonneau in rear.

F — Body for electric automobile with extra
front seat — ^provision for toux Irays oi b«Lllei:les^

THE AUTOMOBILE HAXD-BOOi: 59

BODIES

F(G. 23

60 THE AUTOMOBILE HAND-BOOK

one in front under the . extra seat and three
trays under the seat and rear extension of the
body.

G— Runabout body with imitation hood in
front, containing gasoline and water tanks —
provision for tonneau in rear.

H — Touring car body with folding front seat,
with baggage space— large space for baggage in
the rear of the body.

Body-Hangers, Forms of. Since the incep-
tion of the automobile, the frame or running gear
of the car is in nearly all cases attached to the
springs and the body carried upon the frame.
The parts or in some cases actually extensions of
the frame are or should be properly termed frame-
hangers, but they are erroneously and almost
universally known as body-hangers, from the term
applied to the constructions used in horse-drawn
vehicles. Some forms of frame-hangers are of
pressed steel construction, but the usual forms
are made of drop-forgings. Figure 24 shows
some of the forms of drop-forged frame-hangers
for automobile use: The front or what is
generally known as the pump-handle form of
hanger is shown at J, the rear or fish-hook form
is shown at K and the forms of hangers used for
attaching the inner ends of the springs to the
frame are shown at L and M.

Bolts and Nuts, Locking Devices for— See

Locking Devices.

THE AUTOMOBILE HAND-BOOK

Bore and Stroke, Relation of Horsepower

to. The horsepower of a gasoline motor when
the explosive charge and degree of compression
are at their best, depends entirely on the piston

displacement or the volume swept out by the
piston and the number of revolutions made by
the motor. The term cylinder volume should
not be confused with the expression piston dis-
placement, as the former includes the combustion

62 THE AUTOMOBILE HAND-BOOK

space, along with the piston displacement. As a
naatter of fact, the smaller the cylinder volume is
in relation to the piston displacement, the greater
will be the eflSciency of the motor, as the com-
bustion space will be smaller, the degree of com-
pression consequently greater and the residue of
burned gases smaller. The only limitation to the
degree of compression in the combustion chamber
is the danger of premature or spontaneous
ignition of the explosive charge.

Brakes, Elementary Forms of. A brake is

a mechanism which is a necessary part of the
machinery of an automobile and enables the
operator by exerting a slight amount of force on
a lever to reduce the momentum of the moving
car. Brakes used on automobiles may be divided
into three classes: Hub or rear wheel brakes,
transmission and differential gear brakes. Brakes
have also been applied to the tires of the rear
wheels, but have proved unsatisfactory and have
been abandoned. The forms of brakes in use
are single, or double-acting, foot or hand oper-
ated, and of the band, block or expanding ring
types.

Figure 25, at A, B and C, shows three forms
of the simplest type of single-acting band-brake.
This type of brake can only be operated suc-
cessfully with the brake wheel running in one
direction only, which is indicated by the arrows
in the drawing. If the brakes be operated in the

THE AUTOMOBILE HAND-BOOK 0)3

64 THE AUTOMOBILE HAND-BOOK

reverse direction to that indicated by the arrows
the result will be to jerk the lever or pedal out of
the control of the operator of the car.

The three forms of band-brakes shown at A,
B and C are all of the same principle, the differ-
ence being in the location of the fixed end of the
brake-band and the shape of the operating lever.
Type D is a form of double acting block-brake,
which is designed with a view to eliminate any
strain or side thrust upon the shaft of the brake
wheel which may be caused by the braking action
of the device. Types E, G and H are three
types of double acting band -brakes, in which the
brake may be applied with the brake wheel
running in either direction.

Type F is a form of double acting block-brake ,
in which the right hand ends of the brake-shoe
aims are pivoted to stationary supports, and the
left hand ends connected together by means of a
link and bell-crank lever as shown in the drawing.

In Figure 26 a form of double acting block-
brake I is shown, which is extremely powerful on
account of its peculiar construction, in that it has
a double leverage upon the brake wheel, which
may be readily seen by reference to the drawing.
Types J and K are of the form known as internal
brakes and of the expanding ring type, the
brakes operating upon the inner surface or periph-
cry of the brake wheel, instead of the outside.
They are known as hub brakes, being usually

'^i"^

THE AUTOMOBILE HAND-BOOK

attached to the hubs of the rear wheels of the
car. Tj^ L shows a form of block-brake in
which the pivoted brake arms are drawn together
by the eccentric located on the brake lever shaft.
When the lever is released the brake-shoe arms

are forced apart by the action of the coil spring
between the upper ends of the arms.

Brake Test with Prony Brake. There is

only one way by which the actual horsepower of
a gasoline motor may be correctly ascertained and
that is by the use of the Prony brake, so called

66 THE AUTOMOBILE HAND-ROOK

after its inventor. This simple device gives the
actual energy in foot-pounds per minute delivered
by the motor at its driving shaft.

The apparatus for making a brake test is fully
illustrated in Figure 27. Two brake-blocks A
partially surround the pulley P and are jittached
to the clamping pieces B and C, which hold the
brake-blocks upon the pulley by means of the
bolts D, springs E and thumb-nuts F. The
lever G is double-ended for the dual purpose of
balancing itself and also supplying a place of
attachment for the weight W to balance the weight
of the spring scale S.

In using this form of Prony brake, the motor
is started in the direction indicated by the arrow
on the drawing, the brake -blocks A are then
tightened by means of the springs E and. thumb-
nuts F. Then the reading of the spring scale S
and the speed of the pulley P are taken.

The motor should be tested at varying speeds
and the pull on the spring scale S noted for each.

The actual horsepower can then be calculated
for each test and what is known as the critical
speed of the motor determined, that is the speed
at which the motor develops the greatest brake
horsepower.

'^The following formula gives the actual horse-
power obtained from the results of a Prony
brake test: Let L be the length of the scale
lever in inches, and S the pull indicated by the

THE ATTOMomLE HAND-BOOK

68 THK AITOMOBILK HAXD-BOOK

spring scale in pounds. If N be the number of

revolutions per minute of the pulley R and B.H.P.

the actual or brake horsepower of the motor,

then

_LXSXN

^•^•^•~ 63,025

Example : A motor of 5 inches bore and stroke
at 600 revolutions per minute gives a pull at the
spring scale of 32 pounds, the scale lever is 24
inches long. What is the brake horsepower of
the motor?

Answer: Twenty-four inches multiplied by 8
and by 600 equals 460,800— this divided by
63,025 gives 7.30 as the brake horsepower of
the motor.

The weight J is shown for use in case the floor
of the testing room should be of brick or cement ;
if of wood the eye-bolt H can be screwed directly
into the floor.

Breakdowns. As breakdowns are of frequent
occurrence it is of the utmost importance that all
the parts of a car that need adjustment or inspec-
tion should be readily accessible. Serious break-
downs should never occur on a well kept car.

The usual breakdowns are due to forgetfulness

•

on the part of the operator to make some

necessary adjustment on the car, or the lack of
tools or extra parts required to repair a break.
On a well kept car troubles as a rule only occur
one at a time and those generally at long intervals.

THE AUTOMOBILE HAND-BOOK 69

A little logical thiuking and a few minutes spent
in testing usually locates a trouble so that when
it is removed a start may be made without further
hunting.

The owner of a car should once in a while
undertake the task of cleaning the car and making
the necessary adjustments therein.

The mechanic may then, under the instruction
of the owner, locate a trouble and remove it in a
very short time. A bad breakdown may be
described as one which will take over half a day
to repair. Many an apparently serious break-
down occurs simply from the fact that the operator
fails to examine the condition of the batteries or
the state of the spark plugs or commutator before
starting on a trip. These details, being very
simple and requiring only a few minutes' work,
Should-never be neglected. Before starting on a
long trip, to insure getting to the end of the
journey without delays, the car should be
thoroughly overhaule*! and anything that might
give trouble carefully inspected.

Breakdowns, Causes of. Any one of the fol-
lowing troubles may be the cause of a motor
stopping or not working properly:

Soot or grease on the spark plug.

Defective insulation of the spark plug.

Points of the spark plug too far apart.

Contacts of the coil vibrator badly corroded.

Broken wires or loose batterv terminals.

THE AUTOMOBILE HAND-BOOK

Leaky admission or exhaust- valve.

Seized piston or bearing.

Broken valve-stem or valve-spring.

Batteries exhausted.

Defective spark coil.

Poor contact at the commutator.

Defective insulation of the secondary wires.

Broken piston ring.

Stuck piston.

Defective packing. C^^

Gams, Shape of. The cam shown at M in
Figure 28 and of the type in general use for lift-
ing the admission and exhaust
valves of gasoline motors, has
two serious objections to its
extended use. On account of
its shape, excessive pounding
of the valve on its seat is pro-
duced and the time of admis-
sion or discharge of the gases
from the combustion cham-
ber of the motor very lim-
ited, as the valve has only a
full lift or opening for a brief
instant of time.

The cam illustrated at N removes the objections
stated above by being of somewhat larger
diameter than cam M, consequently giving an
easier lift to the valve and a longer time for the
valve to remain fully open. To replace the

THE AUTOMOBILE HAND-BOOK

ordinary form of cam by this improvement it is
in most cases simply necessary to shorten the
valve-lifter rod at its upper end, by half the
amount of the increase of the cam diameter, the
lift of the valve remaining the same as before.

Table No. 8.
Dimensions op Cap Sorbwb.

"i?er"

i
t
i

!il

s
II

18
16
14
\2

13
1!
10
9
8
7
7

is
li

h
u

Gap Screws, Dimensions of— Sec Table No. 8.

Carbon, Deposit of. The formation of a car-
bon deposit in the combustion chamber of a
gasoline motor is usually accompanied by the
smell of unburned or unconsumcd gasoline or
burned lubricating oil.

The deposit is caused either by the excessive
use of lubricating oil or too rich an explosive

72 THE AUTOMOBILE HAXD-BOOK

mixture. Premature ignition is often the result
of a sooty combustion chamber; to prevent it
until such time as the obstruction may be
removed, run with as little gasoline and as much
air as possible to prevent or avoid premature
ignition.

Carbon, Use of. Carbcm is the positive ele-
ment or electrode in nearly all commercial forms
of dry and primary forms of batteries, it is also
used as brushes or current distributers for both
dynamos and electric motors. The brushes
which convey the
current from the
storage batteries
to the armature
of an electric au-
tomobile motor
are usually of
carbon.

Carbureters,
Construction of.
'I' he carbureter
shown in the ac-
companying il-
lustration, Fig-
11:0 29, is of the jet form of float-feed tj-pe.

The chani!>c'r A of the carbureter contains the
float li. Iliriiu;;li the center of which passes the
3tcm of the nw<llc-vulvc C, which keeps the pipi-
D leadint; to the (yusoliiie tank normally clo.-«<l.

Qt_L Fig, 29

n = m

E-

— •li-

itfi

-Aj i

41^

(J^ H

5X-D "

CARBURETER

THE AUTOMOBILE HAND-BOOK

When the level of the gasoline in the chamber
A falb, the fioat B. through the links E, small
levers F and grooved collar G. raises the stem of
the needle-valve C, thus permitting more gasoline
to enter the chamber A, until the normal level is
again restored.

The mixing-chamber H has an iniier tube .1,
which surrounds the jet or nozzle K. During
the admission stroke of the motor-piston, air is
drawn into and thnmgh the mixing- chamber H,
in the direction of the arrows, a small stream of
gasoline is in consequence drawn up b_v suction
from the opening in the jet or nozzle K, mixing
with the air in the chamber II. The upper end
of the stem of the needle-valve C is provided
with a small
knob L, by which '
the carbureter
may be flushed
for the purpose
of starting the
motor. .\ny sur-
plus gasoline is
carried off by
means of the
vent M.

The spray
form of float-feed
carbureter shown in Figure :fl). lias the float B and
needle-valve stem C in one pic<o. When the gas-

CARBURETER

THE AUTOMOBILE HAND-BOOK

oline level in the chamber A is lowered, the needle-
valve stem C falls with the float B and allows more
gasoline to enter the chamber A, through the open-
ing in the connection at D. The screw E with
thumb-piece F and lock-nut G is for the purpose of
regulating the volume of the spray at the nozzle
K, by means of the cone-shaped point H of the
screw E. The nozzle K is surrounded by a tube
J, through which the air is drawn by the induc-
tive action of the motor-piston. The carbureter
may be flushed by depressing the float with the
small plunger M, which is kept normally out of
contact with the float by the spring L.

Mixing Valves. Since the adoption of liquid
fuels for explosive motors, numerous forms of
carbureters have been designed, with a view to
eliminate the complications of the float-feed type.

The most practi-
cal form of such
devices, known
as mixing valves,
are very suitable
for marine or
automobile mo-
tors, where the
speed is not con-
s t a n 1 1 y being
changed, and aie
specially adapted for motors that run at a uniform
speed. Figure 3 1 illustrates one form of mixing

THE AUTOMOBILE HAXD-BOOK

valve. It consists of a globular chamber A, within
which is a valve B, controlled by a spring C car-
ried by the seat D on the valve-stem guide E,
which forms a part or portion of the threaded
cover F. The gasoline from the supply tank is fed
through a suitable pipe screwed into the threaded
connection at G, to the opening in the seat of the
valve B. The rate of feed of the gasoline is regu-
lated by means of the needle-valve H, with knurled
thiimb-nut J and lock-spring K. The suction of
the motor-piston draws the valve B from its seat
and at the same time uncovers the opening in the
valve seat lead-
ing from the gas-
oline supply pipe
at G and allows
of the flow of 1
small quantity of
gasoline.

The gasoline
mixes with the air
drawn through
the valve open-
ing and the fric-
tion of passing
around the nar-
row space be-
tween the valve
and its seat insures ti unifonn mixture of gasoline
and tar.

F^'G. 32 K^, ^^

fi,

i-C

fffl

MIXING VAL\

76 THE AUTOMOBILE HAND-BOOK

Another form of mixing valve is shown in
Figure 32, in which the gasoline supply is con-
trolled by the cone point on the stem A of the
valve B. The cone-point of the valve-stem A
entirely closes the opening leading from the supply
pipe at G, but keeps the valve B slightly ofiF its
seat as shown.

The valve B is held in position by means of
the spring E, located around the guide of the
valve-stem, which forms a part of the cover D of
the valve chamber C.

The amount of gasoline fed to the motor is reg-
ulated by the screw F, with thumb-nut J and
lock-nut H.

The air is drawn through the carbureters or
mixing valves in the direction indicated by the
arrows.

Carbureter Troubles. There are several
things which may prevent a proper explosive
charge from reaching the combustion chamber
of a motor. Some of the principal causes may
be enumerated as follows:

A leak or crack in the pipe between the car-
bureter and the admission - valve chamber —
Partially or entirely close the air inlet to the car-
bureter, then try and obtain an explosion from
the motor. If it should start, the trouble is
probably located and the admission -pipe should
be closely inspected for leaks or cracks.

Not enough gasoline — Proceed as above and

THE AUTOMOBILE HAND-BOOK 77

if the motor starts, the nozzle in the mixing-
chamber of the carbureter should be removed and
the opening cleaned by passing a ^^^re through it,
the needle-valve opening should be ti-eated in a
like manner.

Too much gasoline — Shut off the gasoline
supply at the tank and crank the motor. If the
motor starts, the trouble is located and the gaso-
line supply should be regulated, by throttling at
the supply tank, or if possible by replacing the
nozzle with one having a smaller opening.

Dirt in the gasoline — When filling the gasoline
tank always use a strainer- funnel: one that is
fitted ^vith a wire-orau/e screen of very fine mesh.
In the absence of a strainer-funnd, three or
four layers of fine linen may be fitted inside an
ordinary funnel. A piece of chamois skin also
makes an excellent filtering medium. Never
use the same funnel for both gasoline and
water.

Leak in the float — This may be from the fact
that one of the soldered joints has opened, or
minute perforations occurred, by corrosion
due to the presence of foreign sul)stances in the
gasoline. In either case the float will partially
or wholly fill with gasoline and sink to the bottom
of the float chamber, thus opening the needle-
valve and flo(Kling the carbureter. The only
remedv for this is a new float.

Poor quahty of gasoline — This is generally

78 THE AUTOMOBILE HAND-BOOK

indicated by a smoky exhaust with a disagreeable
odor, the motor will misfire occasionally and not
develop its full power. Gasoline should always
be tested with a densimeter when its quality is
in doubt and if it does not show at least 76
degrees it should be rejected. In the absence
of a testing outfit, a handy and fairly reliable
method of testing the fuel is to pour a little of
the doubtful gasoline on the palm of the hand.
If the gasoline evaporates rapidly and leaves
the hand dry and clean, it may be safely used,
but if it evaporates slowly and leaves a greasy
deposit on the hand, its use should be avoided.

Water in the carbureter — All gasoline contains
a slight percentage of water, which, being heavier
than the more volatile liquid, settles to the bottom
of the gasoline tank and eventually finds its way
to the carbureter. This generally happens after
a car has been standing for some days and not in
use. The gasoline supply should be shut oflF at
the tank and the carbureter emptied by opening
the pet-cock usually provided for this purpose at
the bottom of the float chamber.

Stale gasoline — The gasoline in the float
chamber of the carbureter will lose its strength if
the car has been standing for some time not in
use — Shut off the gasoline supply at the tank and
then empty the float chamber by means of the
pet-cock which is usually provided for this pur-
pose. After the float chamber is emptied, close

THE AUTOMOBILE HAND-BOOK 79

the pet-cock and turn on the gasoline supply at
the tank.

Cold weather — Saturate a piece of waste with
some fresh gasoline and insert it in the air-inlet
of the carbureter —In extremely cold weather it
may be necessary to warm the carbureter and
admission-pipe by pouring boiling water over
them, but on any account do not Start a bonfire
under the carbureter.

Water in the gasoline — Pour a small quantity
of the gasoline on a smooth, unpainted metal
surface, the water will separate from the gasoline
and collect in small globules, unless the water
has been purposely combined with the gasoline
by the use of some chemical, at the hands of an
unscrupulous dealer — If this is suspected, a small
quantity of the gasoline when ignited will bum
slowly with a yellowish flame.

Starting crank not turned fast enough — Always
remember that a few quick turns of the crank
will be more likelv to start the motor than ten
minutes of slow pumping, t^

Carbureters, Tjrpes of. Carbureters for gaso-
line motors are of three types : surface carburetcTs,
in which the air supply is mixed directly with
gasoline vapor to form an explosive mixture* —
spray or jet float-feed carbureters, which, by means
of a float, maintain a constant level in the gasoline
receptacle and mixing valves, in which the gasoline
outlet is opened by means of an air valve.

80 THE AUTOMOBILE HAND-BOOK

The surface carbureter is at the present time
almost obsolete, being used only on one or two
motor-bicycles of European make. The rapid
evaporation of the vapor in the surface carbureter,
due to the suction of the motor-piston, causes the
gasoline after a short time to become thick and
syrupy, and if some external source of heat is not
supplied to assist in the evaporation it will cease
altogether. While the surface carbureter is the
most economical of the three forms, it is very
irregular and erratic in its action and requires
constant manipulation of the air and gasoline
vapor cocks to insure at all times an explosive
mixture of uniform (|uality. The float-feed form
of carbureter consists of two principal parts: a
gasoline receptacle which contains a hollow metal
or a cork float, suitably arranged to control the
supply of gasoline from the tank or reservoir, and
a tul)e or pipe in which is located a jet or nozzle
in comnmnication with the gasoline receptacle —
this tube or pipe is called the mixing chamber.
I'he gasoline level is maintained about one-six-
teenth of an inch below the opening in the jet in
the mixing chamber. The inductive action of
the motor-piston creates a partial vacuum in the
pipe leading from the mixing chamber of the
carbureter to the motor, thereby causing the
gasoline to flow from the jet and mixing with
the air supply, to be drawn into the cylinder
of the motor in the form of an explosive mixture.

THE AUTOMOBILE HAND-BOOK

Cardan Joint— See Universal Joints.

Chain, Roller. After a chain has been run
about 2,500 to 3,000 car miles remove it and
thoroughly clean by immersing first in hot water
and then in gasoline. Afterwards it should be
boiled in mutton tallow for at least one-half
hour. The object of boiling the chain in mutton
tallow is two-fold, first it gets the grease into a
fluid state so that it will enter between the rollers
and contact-surfaces of the pins and links and
when cold it will exclude all dust or grit from
entering therein, besides it forms an excellent
lubricant between the rolling surfaces.

The dimensions and strength of standard
sizes of roller chain are given in Table No. 9.

Table No. 9.
Dimensions and Strength of Roller Chain.

Pitch of

Chain In

Inches.

Diameter of

Roller in

Inches.

Width of 1 Breaking j
Chain in i Stress in
Inches. \ Pounds.

1
U

i & i

f &}

5,000
6,500
9,000

Change-speed Gear — See Power Transmission
Devices.

Channel-iron — See Structural Shapes.

Chassis. The word chassis since its adoption
into the English language is taken to mean the
frame, springs, wheels, transmission and in fact

82 THE AUTOMOBILE HAND-BOOK

all mechanism except the automobile body. In
its original French it does not mean all this, but
is strictly restricted to mean the frame, or the
frame and springs-see Running Geai«.

Chauffeur. This term when literally trans-
lated means the stoker or fireman of a boiler.
The use of the word has been extended to the
operator of a motor car, but does not usually refer
to the paid driver, who is generally known as the
mecanicien or mechanic.

Circuit-breaker. A circuit-breaker is a device
consisting of either a solenoid or an electromagnet
which acts automatically to break the circuit of
a storage battery charging plant, when a condition
of cither too low or too high voltage exists.

Circulating Pump— See Pumps.

Circumferences of Circles — See Table No. 6 —

Areas and circumferences of circles.

Clutches, Friction — See Power Transmission
Devices.

Clutch Troubles. Some of the troubles to
which a clutch may give rise are:

Slipj)age of the contact surfaces of the driving
and driven members of a clutch, caused by oil or
grease getting between the contact surfaces, or
need of adjustment to take up wear or lost motion
in the w^orking parts — A little Fuller's earth or
French chalk w411 generally cure the slippage if
one of the contact surfaces is of leather. If both
are metal, a dose of kerosene will in most cases

THE AUTOMOBILE HAND-BOOK 83

remove the grease, but on no account use gaso-
line for this purpose. If the slippage is caused
by need of adjustment, so adjust the contact
surface of the driving or driven member that the
contact surfaces will be closer together than
formerly, when apart.

Clutches of the disk or side-drive form usually
have the contact surface of the driving member
of vulcanized fiber. When badly worn or burnt
from too sudden application of the clutch engag-
ing mechanism, slippage will occur, the only
remedy for which is new fiber pads.

Clutches of any form, having the contact sur-
face of one of the members leather-covered, which
exhibit a tendency to take hold too suddenly,
may be remedied by treating the leather surface
to a generous application of glycerine or castor oil.

K a cone-friction clutch should stick or seize
and all ordinary methods fail to loosen it, with
the high speed gear in mesh, push the car back-
ward and forward several- times. This will
generally free the clutch.

The replacing of the leather on the male
member of a cone-friction clutch of the flywheel
type is usually a tedious process and one that
should be handled by an expert. Owing to the
necessity of removing the male member of the
clutch from the car, this may in some cases
require the complete removal, or at least partial
disconnection of the transmission gear.

84 THE AUTOMOBILE HAND-BOOK

Always get the new leather from the maker of
the car and if possible keep one on hand, to avoid
delay when the renewal of the leather becomes a
necessity.

Coils — See Electrical Ignition, also Induction
Coil.

Combustion Chamber. Thai part of an explo-
sive motor in which the gases are compressed and
then fired, usually by an electric spark, is known
as the combustion chamber. The interior of the
combustion chamber should be as smooth as
possible and kept free from soot or hard carbon
deposits such as are induced by excessive lubrica-
tion or the use of too rich an explosive mixture.

It will be found to be no small task in design-
ing an explosive motor with the usual form of
valve construction and operation, to keep the
combustion chamber do^^^l to the required dimen-
sions and at the same time have it free from
bends or ccmtracted passages between the com-
bustion space and the valve chamber.

Many attempts have been made to obviate this
difficnltv bv niakinij the combustion chamber
simply a straight extension or continuation of the
cylinder. In this manner both the admission and
exhaust-valves can be placed in the cylinder itself
and an ideal combustion space secured. This
plan has, however, certain disadvantages^ from
the fact that it not only lengthens the motor» but
requires a more complicated form of valve operat-

THE AUTOMOBILE HAND-BOOK sr,

ing mechanism tnan if the valve chamber were at
the side of the cylinder as is usual.

Combustion Chamber, Dimensions of. If it

is desired to ascertain the cubic contents or
dimensions of the combustion chamber of an
existing motor, they may be found by filling the
combustion space with water, then obtaining the
weight of the water in ounces, which multiplied
by 1.72 will give the capacity of the chamber in
cubic inches. If a motor is to be designed with
a given bore and stroke, the first thing to do is
to decide on the amount of clearance or combus-
tion space at the end of the cylinder for the gases
to occupy after compression.

If the combustion space could be made as a
continuation or extension of the cylinder bore, it
would be an easy matter to determine the required
clearance, as it would simply l)e some fraction of
the total piston stroke.

But as the general design of a combustion
chamber deviates widely from a plain section or
length of a cylinder as above described, being in
some cases flat oval, elliptical, semi-spherical and
even rectangular in cross section, some other
method must be used to calculate the re(|uired
clearance.

To do this correctly the contents of the com-
bustion chamber in cubic inches must first be
ascertained, and then apportioned between the
valve chamber or chambers and the clearance

86 THE AUTOMOBILE HAND-BOOK

proper which lies directly behind the piston
head.

To find the cubic contents of a combustion
chamber when the degree of compression in
atmospheres is known: Let S be the stroke of
the piston in inches and A the area of the cylinder
in square inches. If N be the number of atmos-
pheres compression and C the required contents
of the combustion chamber in cubic inches, then

SX.\_

(N-1)

Example: Find the cubic contents of the
combustion chamber for a motor of 4-inch bore
and 5-inch stroke with 4 atmospheres compression.

Answer: Five multiplied by 12.56 equals
62.83, which divided by 3 gives 20.94 as the
number of cubic inches required.

Commutators, Care of. Commutators with a
make and break form of contact-maker, should
have the platinum contacts cleaned at least once
a week, with a small piece of fine sandpaper or
emery cloth.

Commutators having a rotary wiping form of
contact, should have the brass or copper segment
thoroughly cleaned in the manner just described,
and all grease or dirt removed from the fiber
portion of the commutator.

All thumb or lock-nuts and adjusting screws
should be carefully gone over, and the condition
of the wiring from the battery and coils examined

THE AUTOMOBILE HAND-BOOK

Fig 33

very closely. Ten minutes spent in this manner
once a week may save long delays and much
laborious work at some future time.

Commutators, Forms of. The commutator

of the ignition system of a multi-cylinder gasoline
motor has a three-fold use: To switch the
battery current in and out of the electrical circuit
at the proper time — To transfer the battery
current successively from one coil to another —
To vary the point or time of ignition of the explo-
sive charge in the motor cylinder.

The commutator shown in Figure 33 is for a
four-cylinder motor and is designed for use with
induction coils without
vibrators, which are
known as single-jump
spark coils. The studs of
the screws A and springs
B are carried by insulated
bushings located in the
back of the commutator
case. The nose of the cam
C successively engages

with the springs, causing them in turn to make
contact with their respective screws. The bat-
tery and coil circuit is completed through the
screws A, and a ground to the cam C, by means of
the springs B, when in contact with their respec-
tive screws and the cam.

This device is said to cause a good spark at

COMMUTATOR

THE AUTOMOBILE HAND-BOOK

COMMUTATOR

the plug on account of the quick break between
the spring and the screw, the electrical circuit
being broken the instant the spring leaves the

screw and before the cam
has allowed the spring to
resume its normal posi-
tion. This form of com-
mutator cannot be short-
circuited bv oil or dirt
getting between the
spring and the screw, as
I lie spring B only forms
a part of the electrical
circuit when in contact with both the cam C and
the screw A.

Another form of commutator for a four-cylinder
motor is illustrated in Figure 34, which has a
rotary spring contact-maker A, which engages
su(*f.'essively with the heads B of the screws C.
'i'lie screws are spaced equidistant around the
fiber ring D, which also forms the case of the
commutator and are held in position by the lock-
nuts E. The spring contact-maker A is attached
to a hub F on the cam shaft of the motor. The
time or point of ignition may be varied by
moving the commutator case about its axis by
means of a rod attiichcd to the nrm G.

Figure 3.) shows two commutators of very
similar construction. The one at the left in the
drawinii: is for a two-cvlindor motor and has

THE AUTOMOBILE HAND-BOOK

flat spring-steel contact-makers. The commu-
tator sho^Ti at the right of the drawing is for
a four-cylinder motor and instead of having flat
spring contact- makers, it has either carbon or
copper contact-brushes, which are held against
the commutator by short coil springs in the insu-
lated bushings located around the periphery of
the commutator case. The commutator is made
of vulcanized fiber with a short brass or copper

COMMUTATORS

Fig. 35

segment, which is grounded to the cam shaft as
shown.

The forms of commutators illustrated in the
drawings may be constructed for use with a motor
of any number of cylinders, by increasing or
decreasing the number of contact-makers located
around the commutator — see also Electric Motors.

Compensating Joints. On account of the

distortion of the frame or running gear of an
automobile, due to unequal spring deflection and
irregularities of the road surface, means should

BBH

THE AUTOMOBILE HAND-BOOK

be provided to insure flexible joints or connections
between the various rotating parts of the mechan-
i-sm of a car. The device shown in Figure 36 is
not. susceptible to any great amount of angular
distortion, but will transmit power with a
practically uniform velocity, with the axes of the
shafts considerably out of alignment in vertical or
horizontal parallel planes.

Fig. 36

COMPENSATING DEVICE

The form of compensating joint shown in
Figure 37 may be operated with the axes of the
shafts at an angle to each other, or with the shafts
out of alignment with each other in vertical or
horizontal parallel planes and has quite a range
of operation with either condition. Both forms
of the device ref]uire to have bearings on either
side, as shown, to insure their proper working.

THE AUTOMOBILE HAND-BOOK

Compressed Air — See Air, Properties of.

Compression, Advantages of. The compres-
sion pressure of an explosive motor should be as
high as is possible, without danger of reaching
the degree of compression at which premature or
self-ignition of the charge would occur.

A high degree of compression is of great ad van-

rfHB

f . I I

i^ — r

"^^J

rSID

Fig. 37

COMPENSATING JOINT

tage, but it is not generally known that during
compression there is a loss of heat from the gases
to the walls of the motor cylinder. If the time
or period of contact of the gases with the cylinder
walls were less, the heat losses would be smaller.
Hence the mean temperature of the gases during
the compression stroke of the motor increases
with the motor speed and consequently the gases

92 THE AUTOMOBILE HAND-BOOK

ignite far more readily when the motor is running
at a high rate of speed, than when running slowly
or being operated by hand.

The higher the compression, therefore, the
quicker the ignition and consequent expansion of
the gases take place, thereby causing them to
attain a greater initial pressure, on account of
the lesser heat losses through the cylinder walls.
As it takes a certain length of time to dissipate
or radiate a certain amount of heat, it follows as
a natural sequence that the shorter the time
occupied by the burning gases to attain their
highest pressure, the smaller the heat losses by
dissipation or radiation. The principal gain by
the use of high compression is secured from the
fact that the motor may be run at a greater
number of revolutions per minute, thus having
more working strokes or power impulses and
hence greater power, than if using a lower degree
of compression and consequently slower speed.

Compression, How to Calculate. The com-
pression in atmospheres of a motor may be readily
found by dividing the cubic contents of the piston
displacement by the cubic contents of the com-
bustion chamber in cubic inches, and then adding
one to the result.

To ascertain the compression in atmospheres
of a motor, when the cubic contents of the com-
bustion chamber are known : I^et S be the stroke
of the piston in inches and A the area of the

THE AUTOMOBILE HAND-BOOK 03

cylinder in square inches. If C be the contents
of the combustion chamber in cubic inches and
N the required compression in atmospheres, then

Example: Find the compression in atmos-
pheres of a motor of 4-inch bore and 6-inch stroke,
whose combustion chamber has a capacity of
18 cubic inches.

Answer: Six multiplied by 12.56 equals 75.36,
which divided by 18 gives 4.19, and 4.19 plus 1
equals 5.19, or the compression in atmospheres
required.

If it is desired to ascertain the compression in
atmospheres of a motor, the combustion chamber
of which is of such shape that its dimensions
cannot be accurately calculated , its cubic contents
may be found by filling the combustion chamber
with water, and after removing the water, ascer-
taining its weight in ounces, and then multiplying
the result by 1.72. This gives the capacity of
the combustion chamber in cubic inches. The
compression of the motor can then be readily
Calculated from the formula given herewith — see
also Air, Properties of Compressed.

Compression, How to Test for Leaks in.

To discover if there are any leaks in the com-
pression of a gasoline motor, a small pressure
gauge reading up to 75 pounds should be fitti

94 THE AUTOMOBILE HAND-BOOK

into the spark plug opening in the combustion
chamber by means of a reducing bushing. When
turning the starting crank of the motor slowly
the gauge should indicate at least 60 pounds per
square inch if the compression is in good
condition.

To test for leaks, fill a small oil can with
soapy water and squirt round every joint where
there may be a possible chance for leakage. Get
an assistant to turn the crank and watch for
bubbles at the joints.

If the joints are all tight, next examine the
condition of the admission and exhaust-valves
and if either of them needs regrinding, it should
be done, first with fine emery powder and oil,
then finished with tripoli and water.

When the valves have been ground to a perfect
fit, if the compression still leaks, the piston rings
should be examined, as the trouble will be found
to be with them — see Piston Rings.

Condenser, Use of. A condenser is used in
connection with a Rumkorff or jump-spark form
of induction coil to take up or absorb the static
charge of electricity, occasioned by the self-
induction or electrical reaction in the primary
winding of the coil upon the breaking of the bat-
tery circuit by the interrupter or vibrator. This
static charge is given up or discharged into the
primary winding of the coil along with the battery
current upon the closing of the circuit, thus

THE AUTOMOBILE HAND-BOOK 95

intensif}dng the action of the secondary winding
of the coil in a great degree.

By absorbing the static charge of electricity
the condenser helps to decrease the spark or
arc between the platinum contact points of
the . interrupter or vibrator, thereby lengthening
the life of the platinum contacts by reducing the
erosive action of the induced current spark. A
jump-spark coil very often refuses to work prop-
erly on account of the condenser connections
having become loose — see Electrical Ignition.

Gonstraction of a Gasoline Motor — See Gaso-
line Motor Construction.

Contact-breaker. Some forms of high speed
gasoline motors with an induction coil of the
single- jump-spark type, have a device known as
a contact-breaker to open or break the electric
circuit of the battery and coil, at the proper time
for the passage of the arc or spark at the points
of the spark plug. On account of the extremely
high speed of such motors, and to allow time for
the magnetism or magnetic flux in the core of the
coil to attain a density sufficient to produce a
good spark at the plug points, it is found necessary
to keep the battery and coil in a closed circuit,
except during the brief interval necessary for the
passage of the spark at the plug points.

Figure 38 illustrates one form of contact-
breaker. The left-hand end of the double lever
b kept in contact with the lower end of the

THE AUTOMOBILE HAND-BOOK

insulated pin, by means of a short spring
immediately below it. When the nose of the
cam engages with the roller in the fork or jaw at

the right-hand
end of the
double lever, in-
stant separation
of the nose of
the insulated pin
and the left-hand
end of the
double lever
takes place,
breaking the
electric circuit and causing a spark to occur at
the points of the spark plug.

The electric circuit of the battery and coil is
completed by one wire being connected with the
lock-nuts on the upper end of the insulated pin
and the other wire grounded on the case of the
contact-breaker.

Contact-maker. One of the simplest methods
of electric ignition for explosive motor use is that
known as the singlc-junip-spark system, with
which a plain induction coil without a vibrator or
trembler is used. The secondary spark is pro-
duced by means of a mechanical device operated
by the cam shaft of the motor. The device^,
illustrated and which are known as contact-
makers, cause a spark to arc or jump between

THE AUTOMOBlLfc: HAND-BOOK

the points of the spark plug in the combustion
chamber of the motor.

Figure 39 shows one form of contact-maker.
The case A is usually attached to the gear box of
the motor. Attached to
a boss on the inside and
near the upper end of the
case is the trembler B,
consisting of a flat steel
spring with a nose at its
lower end. Near the
center of the spring b a
platinum contact - point
C. On the opposite side
of the case is a bushing
with insulation E, carry-
ing the screw D, which is so adjusted that it docs
not quite contact with the platinum point C of
the trembler. As the cam F revolves in the
direction indicated by the arrow, it comes in
contact with the nose of the trembler B, and
pushes the platinum point C still further away
from the screw D. Shortly before the cam has
arrived at- the position shown in the drawing, it
has released the nose of the trembler, allowinf;
it to fall; this action produces a vibrating effect,
opening and closing the circuit repeatedly and
with great rapidity, between the point C and
screw D.

This is supposed to cause a stream or succession

THE AUTOMOBILE HAND-BOOK

Fig. 40

of sparks to occur between the plug points in the
combustion chamber of the motor. In practice,
however, and at a high rate of speed, only a
single spark occurs.

Another form of contact-maker is shown in
Figure 40. The trembler B has a small roller

upon its lower end which
at the proper time is
engaged by the nose of
the cam F. The screw
D is carried in a metal
block I, which is at-
tached to the back of the
case A by suitable insu-
lating bushings E. The
screw H in the insu-
lated bushing at G,
makes the electrical con-
nection from the coil
iind battery, through the
block I and screw D, to
the platinum contact C on the trembler B. The
operation of this device is precisely the same
as that of the one shown in Figure 39.

Coupling, Flexible— See Universal Joints.
Current, Commutation of Secondary. There

have been numerous devices made for this pur-
pose, but it is almost an impossible proposition
to switch the secondary current properly on
account of its great intensity. It will arc around

CONTACT MAKER

THE ArTOMORlLE IIAXD-HOOK

\)\)

almost any forn) (^f comnnitator \\m\ couid Ur
devised of practical working diinonsions.

Current, Direction of. The direction of a

current of electricity flowing in a wirc^ may he
readily ascertained l)y reference to Figure 41.
Place an onlinary pocket compass al)ove the
wire and in the position shown. If the needle
points to the North pole of the com[)ass, tlu*

Fig 41

+ «^l

POLE FINDER

current will be flowing in the wire in the direct ioii
indicated 1)V the arrow in the upper view, and
the end at the left will he the Positive ]>()le or
terminal of the wire. If on the other hand the
needle points to the South pole of the compass,
the current will be flowing in the opposite direc-
tion as indicated bv the arrow in the lower view
in the drawing, and the end at the* left will in
this ease be the Negative pole or terminal of the
wire — see also Polarity.

100 THE AUTOMOBILE HAND-BOOK

Cylinder-jacket — See Water-jackets.
Cylinder, Method of Boring a. A good way

to bore a cylinder is to make a boring-bar to fit
in the drill socket of a back-geared drill press
and a brass or phosphor bronze bushing to fit in
the center hole of the table of the drill press.
The cylinder can be clamped to the table of the
drill press by its flange and bored out with a cutter
set in the boring bar. Not less than three, and
preferably four cuts, should be taken to make a
good job. A mandril should then be made with
two flanged hubs, one of which should be fastened
to the mandril and the other turned slightly taper
so as to make a snug fit in the cylinder bore
when in place. The ends of the cylinder can
then be finished on the mandril and a perfect job
will be the result. In case a back-geared drill
press is not handy the cylinder can be clamped
to the carriage of the lathe, bored out with a
bar in the lathe centers and the ends finished in
the manner above described, but it is a much
slower job than in a drill press. The cutter for
the bar should be made from a piece of round
tool steel not less than five-eighths of an inch
diameter. It can then be readily adjusted to
any desired angle to obtain the best cutting
effect.

Cylinder, Scratched — See Scratched Cylinder.

Decimal Fractions of an Inch. See Table
No. 10.

THE AUTOMOBILE HAND-BOOK

101

Table No. 10.

Decimals op an Inch for Each ^.

Ads.

Decimal

Fraction

Ads.

Decimal

Fraction

.03125

.53125

.0625

1-16

.5625

9-16

.09375

. 59375

.125

1-8

.625

5-8

. 15625

. 65625

.1875

3-16

.6875

11-16

. 21875

.71875

.25

1-4

.75

3-4

.28125

.78125

.3125

5-16

.8125

13-16

.34375

. 84375

.375

3-8

.875

7-8

. 40625

. 90625

.4375

7-16

.9375

15-16

. 46875

. 96875

1-2

Densimeter, Use of. The scale generally in
use for indicating the densities of liquids is that
of Baume. On this scale the zero point cor-
responds to the density of a solution of salt of
specified proportions, while 10 degrees corresponds
to the density of distilled water at a specified
temperature.

Figure 42 shows the form of densimeter
generally used for testing gasoline.

Gasoline for explosive motor use should test at
least 76 degrees Baume.

Deposit of Carbon in Combustion Chamber —
See Carbon, Deposit of.

102

THE AUTOMOBILE HAND-BOOK

Diagram, Indicator — Sec Indicator Diagrams.
Diagram, Wiring, for a Single Cylinder
Motor. Diagram No. 2 shows a method of
wiring for a single cyhndcr
motor, using two sets of dry
batteries — a storage battery
and a set of dry batteries —
or a set of dry batteries and
a generator. By moving the
switch finger, either the genera-
tor or the battery may be used
as desired, or both cut out.

Differentia! Gear — See
Power Transmission Devices.
Don'ts. In the first place
DENSIMETER I don't forget to ascertain the
fact that the ignition mechan-
ism is retarded before cranking the motor. Many a
sprained wrist and not a few cases of broken
heads or arras have been caused by the neglect of
this simple precaution. It is a good plan to have
the ignition-contro! spring so actuated that in its
normal position it is always retarded.

If the motor should not happen to start the
first time, don't forget to keep out of the way of
the crank when the motor is stopping. It might
take a turn backwards and take the crank with it.
Don't foi^et to close the battery switch before
starting the motor.

Don't allow the motor to stand in such a

THE AUTOMOBILK HAN'D-BOUK

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104 THE AUTOMOBILE HAND-BOOK

position that with the battery connected, the
vibrator of the spark coil will work. It is almost
the same as a short-circuit, and will run down
the battery rapidly.

Don't use a match or a small torch to inspect
the carbureter. It sometimes leads to unex-
pected results.

Don't forget to fill the gasoline tank before
starting.

Don't smoke while filling the gasoline tank.

Don't take out all the spark plugs when there
is nothing the matter, except that there is no
gasoline in the tank.

Don't forget to always have an extra spark
plug on the car.

Don't allow the motor to race or run fast when
out of gear. If the car is to be stopped for a
few minutes, without stopping the motor, retard
the ignition and also throttle the charge, so that
the motor will run as slowly as possible.

Don't fill the gasoline tank too full, leave an
air space at the top or the gasoline will not flow
readily.

Don't have any open hole in the gasoline
tank. When the car is washed water may run
in this hole, mix with the gasoline and cause
trouble.

Don't put grease in the crank case of the
motor, it will clog up the oil holes and prevent
the oil from circulating.

THE AUTOMOBILE HAND-BOOK 105

Don't fill the gasoline tank by lamp or candle
light, something unexpected may happen.

Don't keep on running when an unusual noise
is heard about the car, stop and find out what
it is.

Don't start or stop too suddenly, something
may break.

Don't pour gasoline over the hands and then
rub them together. That rubs the dirt into the
skin. The proper way to do is to saturate a
towel with gasoUne and then wipe the dirt off.

Don't forget to examine the steering gear
frequently.

Don't fail to examine the pipe between the
carbureter and the admission-valve occasionally.
The pipe connections sometimes get loose and
allow air to enter and weaken the mixture.

Don't forget to see that there is plenty of water
and gasoline in the tanks.

Don't fail to clean the motor and all the wear-
ing parts of the car occasionally.

Don't forget to oil every part of the motor
where there is any friction, except the valve

stems.

Don't spill the gasoline on clothing and then
strike a match to light a pipe, some one may be
sorry afterwards.

Don't go out for a run without a complete
equipment of tools, extra parts, gasoline, and tire
repair outfit, or a late return may be expected.

!06 THE AUTOMOBILE HAND-BOOK

Don't let a willing bystander fill up the gasoline
tank with water.

Don't leave the water in the circulating system
on a frosty night, except with 40 per cent of
glycerine in it, and never when below zero.

Don't start away with the brake on and
wonder why the motor is not working well, and
in conclusion.

Don't let the starting handle fly off and hit
somebody on the chin. /^

Driving-wheels, Large versus Small. The

larger the wheels, the less power should be
required to drive a car. Theory shows that the
road resistance decreases in proportion as the
wheel diameter gets larger. The result of ex-
periments to verify this do not show quite such
favorable results, but a gain almost in proportion
to the scjuare root of the wheel diameter has been
obtained. The principal reasons why large
wheels are not more used arc as follows:

The center of gravity of the car is raised and
mak^s the car less stable in turning comers.
They arc more expensive and more liable to
injury than wheels of smaller diameter. They
increase the cost of the tires enormously. They
make access to the seats more difficult on account
of the increased height of the car.

Dry Batteries —See Batteries, Dry and
Primary.

Dynamo — See Generator.

THE AUTOMOBILE HAND-BOOK 107

Dynamometer. A dynamometer is a form of
equalizing gear which is attached between a source
of power and a piece of machinery when it is
desired to ascertain the power necessary to operate
the aforesaid machinery with a given rate of speed.

Efficiency, Electrical — See Electrical Horse-
power.

Efficiency of a Gasoline Motor. In text-
books the efficiency of a motor is usually con-
sidered as the relation between the heat-units
consumed by the motor and the work or energy
in foot-pounds given out by it. If the heat-units
(which are measured by the quantity of fuel
supplied to the motor) be large compared to the
work or energy given out by the motor, its
efficiency is small.

At the present time the quantity of liquid fuel
consumed by an explosive motor for automobile
use is of secondary importance. The fuel econ-
omy of a motor is important, but it does not
usually occupy the first place in automobile
construction. The consideration of primary
importance is to obtain the maximum amount of
power from a motor of minimum weight. As
only about one-fiftli of the heat-units consumed
by an explosive motor are utilized or given up in
the form of work or energy, there is consequently
room for great improvement.

The power for weight efficiency of a motor
increases almost in proportion to the speed with

lOS THE AUTOMOBILE HAND-BOOK

high speed explosive motors, but the fuel efficiency
of a motor decreases with the speed beyond
certain limitations.

Efficiency of Power Transmission — See

Transmission of Power.

Electrical ChaJ^^ing Outfits— See Batteries,

Drj- and Primar\', Battery Charging Outfit and
Storage Battery Chaiging.

Electrical Horsepower. One electrical horse-
power is equal to the current in amperes multi-
plied by the electro-motive force or voltage of
the circuit and divided bv 746.

Ix*t C be the current in amperes and E the
voltage of the circuit. If E. H. P be the required
electrical horsejwwer, then

746

In practice with motors of small power, 1,000
watts arc necessary to deliver one mechanical or
brake horsepower at the driving shaft of the motor.

If the actual or bnike horsepower of an electric
motor be known, the efficiency of the motor
mav be readilv found bv the following formula:

If E be the voltage i>f the circuit and C the
current in ampores consuinctl by the motor, let
B. H. P be the *^ ** horsepower of the motor
and e the e^ he motor, then

^ PX746
XC

THE AUTOMOBILE HAND-BOOK

109

Table No. 11 gives the electrical horsepower
of motors with voltage from 20 to 100 volts, and
current strengths from 10 to 80 amperes.

The mechanical efficiency of a motor may be
found by use of the table as follows:

Example: Required the mechanical efficiency
of a 40- volt, 60-ampere motor, which is rated by
its maker as of 3.25 horsepower — the motor
when under full load using 80 amperes.

Answer: Reference to the column in the table
corresponding to 40 volts and 60 amperes gives
3.22, while the 80 ampere column gives 4.29.
Then 3. 22 divided by 4.29 gives 0.75, or 75 per
cent, as the mechanical efficiency of the motor.

Table Xo. 11.
Electrical HoRSEPowEFt of Mr/rous.

Current in

Arr.pen;H,

Volt-
age.

.30

40
1 07

r/)

.29

.54

.79

I 01

.54

1.07

1.61

2 n

2 6H

.3 22

.79

1.61

2.41

.3 22

\ 02

\ H2

1.07

2.14

.3.22

4 . 29

5 .30

1.3

100

1.34

2.68 4.02

r
1

5 .30

7 'H

H>,

'/
'/

ir,
7 . r/)

Hf)

2 H

4 2'.f

4.3

>, '/<

Electrical Ignition. 'Vhcrc urc, fwo ut*'^)tfA^.

of producing an electric spark Vtr ij/nition pur-
poses: The first, by mcMu-, of an ttifinf^tou * o\\
which has only a .single wiri'!inp^, 'ornj/'/^/J '/f a
few layers of iasulat^^l ^^-opj^^-r v/jr*- '/( l;»r/<' ^i//!.

110 THE AUTOMOBILE HAND-BOOK

wound upon a bundle of soft iron wires, known
as the core. The second, by the use of an induc-
tion coil with a double winding upon its core.
The inner winding being composed of a few
layers of insulated wire of large size, as in the
coil just described, and an outer winding consist-
ing of a great many layers of very small insulated
copper wire, in fact, several thousand feet in
length.

The coil first described is known as a primary
spark coil, from the fact that the spark or arc
is produced by the direct efiPect of the battery or
generator current flowing in the coil. This form
of spark will not arc or jump across a space
between two points, but simply occurs between
the contact points on the breaking of the contact.

The second form of induction coil is commonly
known as a secondary spark coil, because the
arc or spark is produced in the secondary wind-
ing of the coil, and will jump or arc across a
space between two fixed points, without the points
first coming in contact.

Induction Coil. Induction is the process by
which a body having electrical or magnetic prop-
erties calls forth similar properties in a neighbor-
ing body without direct contact. This property
is known as self-induction and is caused by the
reaction of difTcrcnt parts of the same circuit
upon one another, due to variations in distance
pr current strength. The current produced by an

THE AUTOMOBILE HAND-BOOK

111

induction coil has a very high electro-motive force
and hence great power of overcoming resistance.

The average user of an automobile is well
aware that without the battery and the spark coil
the motor would not operate. He has learned
that, when the spark fails, there are certain
forms to be gone through to ascertain the cause
of trouble, but as there are other diflBculties, it is
desirable that more should be known of this im-
portant subject.

If a current of electricity be caused to flow
through a straight conductor forming a part of a
closed electric circuit, lines of force, commonly
called magnetic whirls or waves, are induced in
the air and rotate around the conductor.

If the current of electricity be flowing in the
circuit and through the straight conductor from
right to left, as
shown in the up-
per view in Figure
43, the lines of
force or magnetic
whirls will rotate

Fig. 43

» /

-rt-

* »

/ 4

*--^§'-®-(j^-(^^

A
J

SWITCH - + BATTERY

-ir

'~*^

/ \

around the con-
ductor from left to
right, or in the
direction of the
hands of a clock.
On the other hand, if the conditions be reversed
and the current flows from left to right the lines

SWITCH + -BATTERY
INDUCTION COIL

112 THE AUTOMOBILE HAND-BOOK

of force or magnetic whirls will rotate from right
to left, as shown in the lower view in Figure 43.
The direction of rotation of these lines of force
or magnetic whirls may be positively determined
by the use of a galvanometer, an electric testing
instrument having a needle similar in appearance
to that of an ordinary compass. Upon placing
this instrument in the path of the lines of force
and making and breaking the battery circuit by
means of the switch, the needle of the galvanoui-
eter will be deflected from its zero point in the
direction of the rotation of the lines of force. If
the direction of the flow of the electric current
through the circuit be changed by reversing the
poles of the battery, the needle of the galvanom-
eter will be deflected from its zero point in the
opposite direction. Whether these lines of force
or magnetic whirls rotate continuously around
the wire has not been demonstrated. They
rotate with sufficient force to be tested by the
galvanometer only until the electric current in
the closed circuit has reached its maximum value
after closing the circuit: that is to say, only
during the infinitesimal space of time required
by the current to reach its full value or power.

If, instead of a straight conductor, a loop of
insulated wire, in the form of a circle, be utilized
for the passage of the current, as at A and B in
Figure 44, the lines of force will still rotate around
the wire as shown, their direction being depend-

THE AUTOMOBILE HAND-BOOK

113

ent on the direction of the electric current. If
the electrical circuit be provided with a current
reverser, or device for changing the battery con-
nections in the circuit from positive to negative
and vice versa, the lines of force can be made to
rotate rapidly first in one direction and then in
the other, as indi-
cated in Figure 43.
Suppose this
loop of insulated
wire be composed
of a great number
of turns, it then
becomes a coil or
closed helix, and
as all the lines of
force cannot pass
between the turns
of the electrical
conductor forming
this helix they
must pass com-
pletely thi'ough the helix instead of rotating
around a single loop, as at A and B, Figure 44.
K the current flows through the conductor in the
direction indicated by the arrows, at C in Figure
44, and over and around the coil in the direction
shown, the Unes of force will flow through the
coil towards the observer, and complete their path
or circuit through the air, returning into the coil

INDUCTION COIL

114 THE AUTOMOBILE HAXD-BOOK

at the opposite end. If the current be reversed
and flow around the coil in the direction of the
hands of a clock, the Hnes of force will flow
through the coil in the opposite direction, that is,
away from the observer, as at D, Figure 44.

This form of coil or closed helix may be
designated as the primitive form of an electro-
magnet. When forming part of a closed electiic
circuit it possesses the property of magnetizing a
bar of wrought iron placed within it. If a short
round bar of wrought iron be placed a short dis-
tance within the coil and the battery circuit be
closed, the iron bar will, if the current is
sufficiently strong, be sucked or drawn into the
center of the coil, and a considerable effort will
be required to withdraw it.

The object of the bundle of soft iron wires,
which form the core of any form of spark coil, is
to increase the magnetic efiPect of the lines of force
or magnetic flux, or rather to reduce the resistance
to their passage through the coil.

As the resistance of air to the flow of the lines
of force is about 100,000 times greater than that
of wrought iron, the introduction of ibe iron core
into the coil increases its magnetic c^ect enor-
mously.

As has been previously stated, when a current
of electricity flows through a conductor or wire
forming a coil or closed helix, lines of force are
induced and flow through, and also around the

THE AUTOMOBILE HAXD-BOOK 115

exterior of the coil. In a like manner, when the
electric circuit is broken, the lines of forct^
suddenly reverse their direction, and travel
through the coil with a tremendous velocity until
they reach a state of neutralization. Durin*^ tlii^i
reverse travel of the lines of forcre through the
coil, a current of electricity is induced in the wind-
ing of the coil, but in the opposite direction t*
that in which the battery current was flowin;^.
The effect of this induced current, wliicli i-. ol'
far greater intensity or pressure than the iKitlcrv
current wliich induced it, is to form an an- or
spark at the breaking point in the cinnit.

Primary Spark Coil. Fi<riire W> shows a
vertical longitudinal section tliroii;^li an indiiclion
coil of the form first described, and known a-, a

A B c T -fl

iiu:i;uiu:j:;/i:;!!;::i:;;;.J'i..m!i:!iiiii:f:;;:;i::iii:iiiiip*^

'■llll"'*T»f*»r'»;'"**)M"'"*l'" .ti.i.|«.i|iii.lil.iliH>li|

T-

4-i.«.i .^ *i-,»i-. .. . «* . *-...* + ..*♦♦#•. f t , rrrrrrrTTTTTiTTiTrrtTTTTTTT

.,<T-t"-;;; '; i::;*r;;;'!!t!;':":"'":;:;':;*'"l:': •"; i.ti.i.i.iii

>AaMMAA«M«^

II' ■•fMM ■

WIPE SPARK COIL ^ Fig. 45

wi])e or touch s])ark coil. It consists of two
principal parts, a core, made of a bundle of soft
iron wire, and a coil of wire around this core
composed of from ,S to 5 layers of turns of insu-
lated copper wire, varying in diameter from No.
16 to No. 12, B. & S. Gauge, according to the

116 THE AUTOMOBILE HAND-BOOK

battery conditions under which the coil has to
operate. The iron core may vary from three-
eighths of an inch in diameter and 6 inches long,
to three-fourths of an inch in diameter, and 12
to 15 inches long, depending upon the intensity
and capacity of the spark required. Reference
to the drawdng will show that the core A has upon
its ends wood or fiber washers D. They may
be square or round. Upon the portion of the
core between the washers is a paper tube E, upon
which the wire forming the primary wmding is
wound. The ends of the wire forming the coil
and shown - at P are connected to the binding
posts or terminals indicated by the letter T, and
located on top of the washers D. The wire B,
forming the primary winding, is usually provided
with an outer casing, as shown at C, to protect
it from water and grease.

The form of induction coil above described is
generally used for ignition purposes on gas and
gasoline motors fitted with a mechanical make
and break form of spark, which is located within
the combustion chamber of the motor itself.

Secondary Spark Coil. Figure 46 shows the
secondary or jump-spark form of coil. It is
composed of an iron core and a primary winding
similar to that described in conjunction with
Figure 45, with the addition of an outer winding
of many turns of fine wire. This wire, of very
small size, is known as the secondary winding,

THE AUTOMOBILE HAND-BOOK U7

118 THL: automobile HANI) BOOK

varying in diameter from No. 36 to No. 40. B. &
S. Gauge, and in length from 5,000 to 10,000 feet.
In the drawing the induction coil is shown
equipped with an cleccro-magnet make and break
or vibrator device, which is the form mostly used
for ignition purposes. The other form, known
as the phiin jump-spark coil, has a mechanically
operated make and break device attached to the
motor to operate the coil.

The arc or spark produced at the breaking
point of the electrical circuit in which the primary
winding of the coil is connected is not utilized for
ignition purposes in this type of coil. When the
circuit is broken the sudden reaction or backward
flow of the lines of force or magnetic flux in the
iron core produce an induced current in the
secondary winding, but in the opposite direction
to that of the battery current. This induced
current is of so much greater intensity and velocity
than that induced in the primary winding by this
same reaction, that the arc or spark induced in
the secondary winding of the coil will jump across
a space f oni one end of the wire to the other,
varying]: from 1 inch to as nmch as 8 or 10 inches
in length, dependent upon the length of wire
in the secondarv circuit, the electro-motive force

of the batt(Ty and the fre(|uen(»y of the interrup-
tions or number of times per minute ttie electric
circuit is made and broken.

In the drawing A is the core, B the primary

THE AUTOMOBILE HAND-BOOK 119

winding and C the secondan\ The two coils are
held in place upon the core by the washers D.
The primary wire B is wound over a paper tube
E, and the secondary wire C is insulated from the
primary wire by a mica insulating tube F. The
coil proper is enclosed in a wood case G.

The terminals or binding posts on top of the
case G are connected with the ends of the sec-
ondary wire 1 and 2. The secondary terminals
are plainly indicated by the letter S. In the base
H of the coil case is the condenser J, an essential
feature of this form of coil, which utilizes th(;
induced primary current to produce a greater
reactive energy in the secondary winding.

At the right-liand end of the coil and outside
the casing G is located the electro-magnetic
vibrator or tremblintjj device, which automatically
makes and breaks the [)riinary circuit. The end
3 of the primary wire is connected with tlie con-
tract screw K through the bracket L. The spring
M, carried by the bracket N, with screw (), is
connected with the terminal or binding post P,
immediately beneath it, by the wire (i through the
bracket N. The end 4 of the primary wire is con-
nected with another terminal or binding post P,
at the other end of the base of the coil. The con-
denser J is connected across the contact points of
the screw K and the spring M, by the wires 5 and
6 and screws Q and X. The condenser is com -
posed of a number of sheets of tinfoil V, laid

120 THE AUTOMOBILE HAND-BOOK

between sheets of specially insulated paper I, with
the opposite end of every alternate sheet of tinfoil
projecting from the paper insulation, as shown.
These projecting ends are connected together
and by the wires 5 and 6 to the contact screw K
and spring M, respectively, as previously de-
scribed.

When the coil is connected in or forms part of
a closed electric circuit by means of the terminal
or binding posts P, on the base of the coil, the cur-
rent flows through the primary windmg B. This
instantly produces a high degree of magnetism in
the core A, and the pole-piece T of the core
extension R becomes strongly magnetic and
attracts the iron button W of the spring M.
This draws the spring M away from the end of
the screw K, and in consequence breaks the
electric circuit. This results in the demagnetizing
of the pole-piece T and the consequent return of
the spring M to its normal position in contact
with the end of the screw K. So long as the
electric circuit remains closed this operation is
repeated at a very high rate of speed. The
effect of this continuous operation of the coil is to
produce an intermittent current in the secondary
winding of high intensity and velocity. If wires
are placed in the holes in the small terminals or
binding posts on the top of the coil and brought
within a short distance of each other, a stream
of sparks will pass from one wire to the other in

THE AUTOMOBILE HAND-BOOK 121

a peculiar zigzag manner and emit a loud, crackling
noise, accompanied by a peculiar odor, caused
by the formation of ozone through the electro-
chemical action of the spark.

Under ordinary circumstances the arc or spark
which occurs on the breaking of the contact be-
tween the platinum points of the screw K and
spring M would not be utilized, but by means of
the condenser in the base, which is connected to
these parts, as before described, the static charge
of electricity generated by this action is stored in
the condenser. When the contact is again made
this stored electric energy is given up or dis-
charged by the condenser and flows through the
primary winding of the coil in connection and in
the same direction as the battery current and
increases the magnetic effect of the core A
enormously.

When the coil is used in connection with a gas
or gasoline motor a form of ignition device known
as a spark plug is used. This is connected with
the secondary terminals and screwed into the
combustion chamber of the motor. A form of
circuit breaker upon the motor is used to make
and break the electric circuit at the desired point,
and the resulting arc or spark inside the combus-
tion chamber ignites the charge of vapor.

This style of coil is sometimes used without the
electro-magnetic vibrator, and a mechanical make
and break device, actuated by the motor, is

122 THE AUTOMOBILE HAND-BOOK

used instead, producing as a rule only a single
spark.

To remove any doubt as to the origin of the
secondary or jump-spark form of induction coil,
it may be here briefly stated, that it was invented
by IlumkorfF in the year 1851, long before the
inception of the automobile.

Electrical Rules and Formulas. Force is

any cause of change of motion of matter. It is
usually expressed by volts, pounds or other units.

Resistance is a counter-force or whatever
opposes the action of another force.

Work is force exercised in traversing or cross-
ing a sf)ace against a resistance or counter-force.
Force multiplied by space or distanc»e represents
work in foot-pounds.

Energy is the capacity for doing work, and is
m(»asured by the work done.

The cause of a manifestation of energy is force.
If this be electro-motive energy or electric energy
in current form it is called Electro-mOtive force.
The practical unit of electro-motive force is the

Volt.

When electro- motive force does work in a
closed electric circuit a current is produced. The
practical unit of current is called the Ampere.

A current of electricity, when flowing in a closed
electric circuit, passes through some substances
more easily than through others.

The relative ease of passage of. the electric-

THE AUTOMOBILE HAND-BOOK 123

current is known as conductance. In practical
calculations its reciprocal, which is called resist-
ance, is generally used. This practical unit is
known as the Ohm.

A current of one Ampere is maintained by one
Volt through a resistance of one Ohm.

Ohm's Law may be generally stated under the
following heads:

The current is in direct proportion to the
voltage of the circuit, and inversely proportional
to its resistance.

1. The current is equal to the voltage divided
by the resistance of the circuit.

2. The voltage is equal to the current multiplied
by the resistance of the circuit.

3. The resistance of the circuit should cijual
the voltage divided by the current recjuired.

Ijei C be the current in amperes flowing in the
closed electric circuit, and E the electro-motive
force or voltage, if II be the resistance of the cir-
cuit when closed, then

^-1 ^^)

V=CXR (2)

R=p (3)

Example: What current vnll pass througli a
primary spark coil having a resistance of 1.5
ohms, with a storage battery of 6 volts in the
coil circuit?

124 THE AUTOMOBILE HAND-BOOK

Answer: By Formula 1, 6 volts divided by 1.5
ohms gives 4 amperes as the current which will
pass through the coil.

Example: The lamp of a small electric
headlight is marked 4 amperes, 2 ohms. How
many cells of 2-volt storage batteries will be
necessary to operate this lamp?

Answer: By Formula 2, 4 amperes multiplied
by 2 ohms equals 8 volts. Therefore 8 volts
divided by the voltage of a single battery, which
is 2 volts, gives 4 cells as the number required.

Example: A dry battery has an electro-motive
force or voltage of 1.5 volts, and an internal
resistance of one-eighth of an ohm. What is its
maximum current capacity?

Answer: By Formula 3, 1.5 volts divided by
0A25 ohms equals 12 amperes as the maximum
current capacity of the battery.

Electricity, Forms of. Electricity or electrical
energy may be generated in several ways —
mechanically, chemically and statically or by
friction. By whatever means it is produced,
there are many properties which are common to
all. There are also distinctive properties. The
current supplied by a storage battery will flow
continuously until the battery is practically
exhausted, while the current from a dry battery
can only be used intermittently: that is, it must
have slight periods of rest, no matter how short,
they may be.

THE AUTOMOBILE HAND-BOOK 125

The dynamo or magneto current is primarily
of an alternating nature or one which reverses its
direction of flow rapidly. In us^, this alternating
current is changed into a direct or continuous
current flowing in one direction only, by means
of a commutator. Any of the forms described
are capable of igniting an explosive charge in a
motor cyUnder, but the static or frictional form
of electricity is not used for this purpose on
account of its erratic nature.

Electric Lamps. It is well to remember that
electric lamps consume a great deal of power.
One 16 candlepower lamp requires about one-
twelfth of a horsepower to operate it. The
electrical energy required per candlepower is a
trifle over 4 watts. A 4-volt, 4 candlepower
lamp would require a storage battery of 24
ampere-hour capacity to enable the lamp to bum
6 hours. The same battery would run a 4-volt,
1 candlepower lanip 24 hours.

Electric Motors. A well designed electric
motor for use in connection with a storage battery
for automobile propulsion must be capable of
withstanding an overload of over 100 per cent for
at least thirty minutes at a time, or for even a
longer period, without unduly overheating. The
motors used on electric automobiles are usually
series-wound, as this type of winding has been
found to give the most satisfactory results in
general use.

126 THE AUTOMOBILE HAXD-BOOK

There are three types of electric motors in
general use, these are:

Shunt- wound motors, in which the field-
magnets are wound with a great many turns of
very small wire, the ends of which arc directly
connected to the terminals of the commutator
brushes.

Series-wound motors, which have the field-
magnets wound with a few turns of very large
wire. One end of this wire is connected to one
commutator brush terminal. The other end of
the wire on the field-coils and the other brush
terminal being connected with a battery or other
source of current.

Com pound- wound motors are a combination of
the above motors, having the field-magnets
double- wound, that is with both shunt and series-
windings.

The armature of an electric motor is built up
of a number of disks of sheet iron, which are
separated from each other by a suitable coating of
varnish or by the use of thin sheets of paper
between the disks, this is to prevent what are
known as eddv currents, which are a source of
constant trouble if not eliminated.

The function of the commutator of an electric
motor is to receive the current from the battery
or other source of power, by means of the
brushes, and transmit it to the windings or coils
upon the periT^^ery of the armature.

THK AUTOMOBILE HAx\D-BOOK 127

The essential features of an electric motor are
as follows:

The brushes, which are located upon and
around the periphery of the commutator and
serve to transmit the current to the commutator
from the outside source or supply.

The commutator or current distributer and
laminated wrought iron armature.

The field-magnets and pole-pieces; the latter
are usually an extension of the magnet core.

The magnet frame, usuaUy of cast steel.

Figure 47 shows a form of series-wound
electric motor of the style most commonly used
for automobile work. The motor is of the four-
pole type, having its field-coils arranged at equi-
distant points around the periphery or circum-
ference of the armature. The armature shaft is
carried by ball-bearings, with suitable screw and
clamp adjustment as shown. The armature is
of the slot-wound type and has a commutator
with self-adjusting carbon brushes. The left-
hand extension of the armature shaft is fitted with
a key and washer for the driving gear or sprocket,
while the right-hand end has a pulley or brake
wheel to use for stopping the car under ordinary
conditions of travel. The magnet frame is of
cast steel and the magnet cores and armature
disks of laminated wrought iron. The field-coils
are machine-wound and the armature coils form-
wound, while both are thoroughly taped and

128 THE AUTOMOBILE HAND-BQOK

THE AUTOMOBILE HAND-BOOK 129

waterproofed. The commutator generally has
the same number of sections as the armature has
slots and is usually of large diameter and wide
contact face.

Electric Motor Troubles. Electric motor

troubles may be classed as follows: Open-
circuits, improper connections and short-circuits.

An Open-circuit may be found at any one of
the following places:

Battery terminals. These may be badly cor-
roded or worked loose, so as to form a poor or
improper electrical contact.

Controller. A connection may have worked
loose, or the spring contact-fingers are not making
good contacts.

The removable plug may be out or not making
a proper contact.

Brushes. One of the carbon brushes of the
motor may have fallen out, or the brush springs
may be too weak to insure a good contact.

The reversing switch may be halfway over,
thus leaving the batteries and motor on an open
circuit.

All points of contact, such as terminals or bind-
ing-posts, brush-holders, switches and controller
spring contact-fingers, should be bright and clean
so as to give a perfect metal-to-metal contarrt.

The fact that the car will not start and the
anuneter shows no current indication is generally

a sign of Improper battery connections.

130 THE AUTOMOBILE HAND-BOOK

When the different trays of the battery are not
properly connected together, short-circuits vni\
occur between these sections and run down or
exhaust the batteries in a very short time. All
battery terminals should be plainly marked so
that it is impossible to make wrong connections.
If the trouble above stated occurs the battery
trays must be wrongly connected amongst them-
selves.

If the ammeter indicates a lai^e current and
the motor refuses to turn, the trouble is what is
known as a Short-circuit, or a path for the
current outside of the motor.

I^ift one of the commutator brushes and if the
amperage shown by the ammc^lcr drops, or
perhaps disappears altogether, om of the field-
coils is short-circuited or there is a broken wire
touching some part of the metal of the car or an
exposed portion of another wire.

Electric Motors, Speed-Regulation of. The

speed and conse(|uently tlie power of an electric
motor may be varied in three ways, as follows:

First, by introducing variable resistances in the
motor and hatterv circuit.

Second, by varying the voltage of the batteries
by different combination of th(» battery trays.

Thirdlv, bv connectinf; the field-coils of the
motor, all in scries, in series- parallel and all in
parallel. Various other combinations of the
above named methods mav also be had.

THE AUTOMOBILE HAND-BOOK 131

Electro-magnetic Vibrator, Independent

Form of. Gasoline motors with liigh compression
and speed require a jump- spark of greater
intensity and volume than those with less com-
pression and speed, to properly ignite the charge.
They consequently require a battery of higher
voltage and greater current volume to induce
a greater flow of the magnetic flux or lines of
force in the iron core of the coil. This has the
efifect of reducing the number of vibrations per
minute of the trembler attached to the coil.
Numerous tests have shown that when the motor
to which such a coil is attached attains a certain
rate of speed, the vibrator refuses to work when
the circuit is closed by the commutator on the
motor. That is due to the fact that the period
of time during which the electrical circuit is closed
and opened by the commutator is not of suflScient
duration to allow the vibrator to properly perform
its function. It is to overcome these objections
that the electro-magnetic vibrator, here illustrated
and described, is intended.

Figure 43 is a plan or top view, clearly showing
the wiring and connections to the terminals or
binding-posts. This is also an important point
in the construction and enables the operator to
connect the vibrator to the coil, battery and motor
without any chart or previous instructions, and if
properly connected as marked, no ground or
short-circuit can occur. P and P are the con-

1 ;V2

THK ATTOMOIULK HAND-BOOK

nections to the primary winding of the induction
(!oil: B and B> the battery connections, and C
and C the connections to the connnutator on the
motor. The wiring shown by the dotted lines

between the ter-
minals P and
B, and also be-
tween P and C,
are merelv
blind or dum-
my wires, so as
to prevent any
mistakes in the
wiring of the
car, as all con-

VIBRATOR

FK5.48

nections hetwoen the battery, coil and motor
must bo made through the vibrator. As this
electro-magnetic vibrator is not connected in
series with the battery and coil current, but is
in a simple shunt from the battery, it utilizes only
a fraction of the battery current, while the
remainder of the current goes directly to the
primary winding of the coil, and the current used
by the coil is at all times controlled by the opera-
tic m of the vibrator.

'Vhe trouble experienced by owners of cars
having multi-cylinder motors equipped with the
ordinary vibrator or trembler form of jump-spark
ignition indicates that something more reliable,
more nearly fool proof, and therefore better

THE AUrUxMOBlLE HAND-BOOK 133

adapted to the requirements of the automobile
maker and user, is required. The use of this
device insures the absolute synchronization or
timing of the spark in multi-cylinder mjtors with
any number of cylinders.

Electro-motive Force, Definition of. The

cause of a manifestation of energy is force; if it
be electric c^nergy in current form it is called
Electro-motive force. An electro-motive force
or pressure of One Volt will force One Ampere
through One Ohm of resistance.

English and French Units— See Table No. 15.
Exhaust, Cause of Smoky. Smoke coming

from the exhaust of a gasoline motor is due to
one of two conditions: Over-lubrication — too
much lubricating oil being fed to the cylinder of
the motor — or too rich a mixture, that is, too
much gasoline and an insufficient supply of air.
The first condition may be readily detected by
the smell of burned oil and a yellowish smoke.
The second, by a dense white smoke accompanied
by a pungent odor.

Exhaust-valves, Diameter and Lift of. The

formulas and Table No. 1, given for admission-
valves, apply also to exhau-it-valvcs. For motors
with excessively hi^li speed, the valve diameter
given by the formula or table should be increased
at least 15 per cent, the formula will then read,

BXSXR

~ 13,000

134 THE AUTOMOBILE HAND-BOOK

where D is the required diameter of the valve
opening, B the bore of the cylinder, S the stroke
of the piston and R the number of revolutions
per minute of the motor — see Admission- valves.
Diameter and Lift of, also Valves.

Explosive Motors, Cycles of. Why two-cycle

and four-cycle as applied to a motor? Why not
one-cycle and two-cycle as used in England?
The questions are by no means new, but are
none the less pertinent for that. In the auto-
mobile business, where many people of com-
paratively little learning in mechanical matters
have to deal with terms which, until now, have
been strange to them, it is desirable that the
language used be as nearly descriptive as possible.
The terms quoted are ambiguous, to say the least.
Why they are used is inexplicable. According
to the best encyclopedic authorities a cycle may
be defined as a series of events or happenings
which recur in regular succession at stated periods
of time. In so-called two or four-cycle motors
the operation, during each successive stroke of
the piston, is not completed within itself, but is
dependent on one or more conjunctive strokes to
complete the event or happening or, in other
words, the cycle of events. It is impossible,
therefore, to describe the movement of the
piston, backward or forward, as a cycle. In the
one case it is only half a cycle and in the other a
quarter and hence it is not entitled to the dignity

THE AUTOMOBILE HAND-BOOK 135

commonly but erroneously applied to it. It
would be more nearly correct to indicate the type
of motor by the number of revolutions of the
crank shaft and flywheel as, for example, one-
revolution motor or two- revolution motor. This
might, for convenience, be changed to one and
two-cycle motor as stated.

Explosive Motors, Types and Forms oL

When explosive motors were first introduced the
use of gasoline in connection with them had not
been considered as a possibility. In later years,
however, coal gas has been largely superseded by
gasoline vapor, and gasoline motors are to-day
far more common than gas motors. The prin-
ciple of operation of the two are identical, how-
ever, and it should be understood that while
gasoline motors are referred to, the description
appUes equally to gas motors.

In 1838 the first two-cycle gas motor was
patented in England by William Barnett.

In 1862 Beau de Rochas formulated the cycle
of operation of an explosive motor, as afterward
built by Professor Otto, commonly known as the
Otto four-cycle motor.

In 1876 the first practical working motor
was introduced by Crossley Bros., of Man-
chester, England, under the patents of Professor
Otto.

Explosive motors are of three forms, known as
stationary, marine and automobile. Their general

136 THE AUTOMOBILE HAND-BOOK

characteristics are implied by their various
designations. The stationary motor may l)e

cither vertical or horizontal. Marine motors,
design d for application to boats, are almost
invariably vertical. Automobile motors are of
comparatively recent intHxluction and of great
variety, the aim of the designers being to secure
the maximum of power and minimum of weight.
Tliev also may be vertical or horizontal.

These three forms may be again divided into
two-cycle and four-cycle t\T)es. In the former an
explosion occurs at every rt*volution. In the
latter there is an explosicm at every alternate
revolulion — see Explosive ]\Iotors, Operation of.

Explosive Motors, Operation of. Explosive

motors are depcndeut for successful operation on
I wo things: First, a char;^^* of gas or vapor,
mixed with suilicicnt air to produce an explosive
mixture, which is to the motor what air is to the
lungs of a human Ix^iug, and scMi-ond, a method
of firing the charge lifter it has ]>een taken into
the combustion chamber ol' the motor.

When coal gas i> used the suj)ply is taken from

the main aud mixed directly vrilli the necessarv

proportion ol* air. When gasoline is used, air is
mixed with it in the correct ])roporton by carbu-
reting devices.

After the ciiargc (il' g;i> mid air Jims been t^ikeii
into the cylinilcr it I> coinprcsst\l, as will be

THE AUTOMOBILE HAND-BOOK 137

Khown later, by the action of the motor itself and
then fired, usually by an electric spark actuated
by the motor, but sometimes by the use of a tube
screwed into the cylinder and heated from the
outside, the heat, of course, being communicated
to the gas. The resulting explosion operates the
motor.

The principal parts of a four-cycle explosive
motor are the cylinder, the piston, the piston rings
which fit into grooves in the piston: two sets of
valves, one to admit the charge and the other to
permit it to escape after the explosion: a crank
shaft and connecting rod which connect it with the
piston head and a flywheel, who,se presence insures
steady running of the motor, and whose further
functions will be better understood as the de-
scription proceeds. In the two-cycle form of
motor there is reallv but one valve, the exhaust
and admission-ports being covered and uncovered
by the piston itself.

All of the parts referred to are of the motor
proper. Other parts, which are separate from
the motor but on which its operation depends,
are the carbureter, which supplies the charge of
gasoline vapor and air for a gasoline motor, or a
mixing chamber for mixing air and gas in the
case of a gas motor, and the batteries and other
parts of the electrical ignition device.

A part which has no connertioii with the actual
running of the motor but witii which practically

138 THE AUTOMOBILE HAND-BOOK

all are fitted is the muffler, whose purppse is to
deaden the sound of the explosion.

The cylinders of all except very small motors
are as a rule partly encased in a chamber through
which water is circulated, the object of this being
to keep the cylinder cool.

Two-cycle Motor. The foregoing outline
of the functions of the parts of the motor pre-
pares us for a description of the two-cycle form
of motor. This particular form of motor draws
in a charge of gas or vapor, compresses it, fires
it and discharges the product of combustion or
burned gases while the crank makes but a single
revolution and while the piston makes one com-
plete travel backward and forward.

Diagram No. 3 shows two sectional views —
that is to say, views of the motor cut in two,
longitudiiuiUy — of thj })rincipal parts of a two-
cycle motor. Other parts, such as the crank
shaft, connecting rod and flywheel, are omitted
to avoid confusion. C is the crank case and A
the admission valve, through which the vapor
passes to the crank case. B is the inlet passage,
through which it passes from the crank chamber
to the cylinder. P is the pist(m. The igniter,
which makes the electric spark when the lower
point comes in contact with the upper, is shown
immediately below the cylinder cover. This
causes the explosion of the vapor. E is the
exhaust port, through which the burned charge

THE AUTOMOBILE HAND-BOOK

139

escape^ after the piston has been driven outward
by the explosion and has reached the end of its
stroke.

Let it be supposed that the motor is still and
the crank chamber C is full of gas or vapor. To
start the motor the piston is started by means of
a crank on the flywheel shaft, and as it passes

TWO-CYCLE MOTOR DIAGRAM

No 3

to the position shown in the left-hand drawing it
forces the charge of vapor througli the [)ort B
into the cylinder. The piston then returns to the
position shown in the right-hand view, moving
away from the crank chamber C, and in doing
so closes the port B and the (exhaust ojx'ning K
and compresses the charge of vapor. '^I'lie points
of the igniter come together, a spark of-rnrs and
the resulting explosion forces tlie piston outward
again. When the piston reaches a point near

140 THE AUTOMOBILK HAND-BOOK

the end of the stroke, as shown in the left-hand
drawing, it uncovers the port E and the burned
charge passes out, the new charge coming through
the port B imnieiHately afterwards.

l^he admission of the new charge to the crank
chamber is controlled by the action of the piston.
As the latter travels outward it has a tendency to
create a vacuum in the crank chamber. This
draws the valve inward and admits the charge of
vapor.

It will he observed that there is a projection
on the head of the piston. This is generally
known as a b«ilHe-plate. Its object is to prevent
the incoming charge from passing directly across
the cylinder iind out at the exhaust port E, which,
it will be ol)serv(Hl, is directly opposite it. The
baffle-plate (iirccts the incoming charge toward
the combustion chamber end of the cylinder,
provi(lin<r. as nearly as may be, a pure charge of
vapor and assisting in the expulsion of the
remainder of the burned gases remaining in the
cylinder as a result of the last explosion.

Fouu-cYCLi: Motor. Diagram No. 4 fur-
nishes two views of a four-(ycle type of motor
with some of the jjarts removed, as in Diagram
No. 30. It show^ a cylindvM' C\ ad mission- valve
A, a pist(m P, and exhaust-valve E in place of
the exhaust-port E in Diagram No. 3.

The left-hand view shows the piston P about to
suck in a charge of va})or, by the same method as

THE AUTOMOBILE HAND-BOOK

141

previously described, through the admission- valve
A into the cylinder C. The suction continues
until the piston P reaches the po'sition shown in
the right-hand view. Then the piston returns
until it again arrives at the position shown in the
left-hand view, compressing the charge of mixture

No 4

FOUR-CYCLE MOTOR DIAGRAM

during this operation. Just before tlie piston
arrives at the end of its travel in tliis direction,
the charge of vapor, now luider (•()ni]>ressi()n, is
ignited by the method previously ex])laine(l and
its expansion forces the })iston back to the position
shown in the riglit-liand view. When the piston
has, for the second time, reached the position
shown in the riglit-liand drawing, a mechanical
device opens the exhaust-valve. The exhaust-
valve remains open until tlie piston has again
arrived at the position in. the left-hand view.
Then it closes, the piston again commences to

i:2 THE AUTOMOBILE HAND-BOOK

draw in a charge of vapor and the cycle of
operation of the motor is repeated.

Fiber, Vulcanized. Paper-pulp treated with
sulphuric acid, washed and afterwards compressed
into sheet or rod form, is known as vulcanized fiber.

Field Coil— See Electric Motors.

Flexible-coupling — See Compensating Joints,
also Universal Joints.

Fluxes for Soldering. Some good fluxes for

soldering purposes are:

Iron or steel. . . .Borax or sal-ammoniac.

Tinned iron Resin or chloride of zinc.

Copper to iron . . Resin.

Iron to zinc Chloride of zinc*

Galvanized iron. Mutton tallow or resin.

Copper or brass . Sal-ammoniac or chloride of zinc.

Lead Mutton tallow.

Block tin Resin or sweet oil.

Flywheels. One of the first and most impor-
tant considerations in connection with the con-
struction of a gasoline automobile motor is the
})rc)per diameter and weight of the flywheel. If
the diameter and weight of the flywheel be
known, the speed of the motor or its degree of
compression will become a variable quantity.
On the other hand, if the speed of the motor and
the degree of compression be fixed, the diameter
or weight of the flywheel rim must be varied to
suit the other conditions. If the speed of the

* Chloride of zinc is simply zinc dissolved in hydrochloric
(muriatic) acid, until the acid is cut or killed.

THE AUTOMOBILE HAND-BOOK 143

motor and its degree of compression be known,
the diameter of the flywheel or the weight of the
flywheel rim may be readily ascertained from the
following formulas.

Weight of Rims of Flywheels. The weight
of the rim of the flywheel is the only portion
which enters into the following calculations, the
weight of the web or spokes and hub being
neglected.

Let M.P be the mean pressure of the com-
pression, and A the area of the cylinder in square
inches. If S be the stroke of the piston in inches,
and N the number of revolutions per minute of
the motor, let D be the outside diameter of the
flywheel in inches and W its required weight in
pounds, then

_ M.PXAXSXN
2560 XD

Diameter of Rims of Flywheels. A motor
that is intended to operate at a slow rate of speed
and consequently with a high degree of com-
pression, will require a flywheel of much greater
diameter and weight than a high speed motor of
the same bore and stroke. It may he well to
remember that within certain limitations tlie
diameter and weight of a flywheel should be as
small as is possible, as an increase in either
means a reduction in motor speed and a conse-
quent loss of power.

To ascertain the diameter of a flywheel when

144 THE AUTOMOHILK HAND-BOOK

all other conditions are known, if D be the
required diameter of the flywheel in inches, then

M.PXAXSXN

2560 X W

Weight of Rims of Flywheels with a
(iivEX Fluctuation in Speed. If it be desired
to run a motor at a practically uniform speed and
with only a slight fluctuation or variation in the
velocity of the flywheel, if W be the required
wcitrht of the flvwheel and X be the allowable
fluctuation of the flywheel in revolutions per
minute above and below its normal spetnl, then

M.PXAXSXN

~ 865 XX

IIousepower Stored in Rims of Flywheels.
It is sometimes desirable to know the amount of
energy or horsepower which may be stored in the
rim of a flywheel of known diameter and weight,
with a given speed. If H.P be the horsepower
stored in the rim of the flywheel, then

D^XWXN

79^2,000

Safe Speed for Rims of Flywheels. The
safe velocitv for the rim of a cast iron wheel is
taken at SO feet per second. Ijvi N be safe speed
of the flywheel in revolutions per minute, then

18.J5:]5

THE AUTOMOBILK HAND-BOOK 145

The mean pressures corresponding to varying
degrees of compression may be found by reference
to Table No. 2 — see Air, Properties of Com-
pressed.

M.P = Mean pressure.

A = Area of cylinder in square inches.

S = Stroke of piston in inches.

N = Number of revolutions per minute.

D= Diameter of flywheel in inches.

W = Weight of flywheel in pounds.

Balancing with the Reciprocating Parts
OF THE Motor. The fly^vhee^ should be bal-
anced as accurately as is possible before mounting
on the crank shaft. In the first place set the
crank shaft on two perfectly straight parallel bars,
one bar under each end. Then attach the con-
necting rod and piston to the crank and turn
the shaft until the crank jaws are parallel with
the floor or in other words at right angles to a
perpendicular line drawn through the center of
the shaft. Place a scale under the (rank pin
or use a hanging scale attached to some rigid
support above the pin and connect it to the crank
pin by a wire or cord sufficiently strong to carry
the weight. Then find the weight of the part^
according to the scale and attach the same
amount to the flywheel at the same distanre from
the shaft on the side opposite the crank, and the
result will be a fairlv balanced motor. It is
impossible to obtain a perfect balance, but the

146 THE AUTOMOBILE HAND-BOOK

above method will assist greatly in reducing the
vibration of the motor.

Four-cycle Motor, Operation of. A four-
cycle motor has only one working stroke or
impulse for each two revolutions. During these
two revolutions which complete the cycle of the
motor, six operations are performed:

1. Admission of an explosive charge of gas or
gasoline vapor and air to the motor-cylinder.

i2. Compression of the explosive charge.

,S. Ignition of the compressed charge by a hot
tube or an electric spark.

4. Explosion or extremely sudden rise in the
pressure of the compressed charge, from the
increase in temperature after ignition.

5. Expansion of the burning charge during the
working stroke of the motor-piston.

(). P^xluiust or expulsion of the burned gases
from the niotor-cvlinder.

As {)ressiire increases with a rise in temperature,
which in a motor the moment after ignition has
taken place is about 2,700 degrees Fahrenheit,
the higher tlie temperature of the ignited gases, the
greater would be the pressure. As this pressure
is expended in work on the motor-piston, the
whole of it might, if expansion of the burning
gases were continued long enough, be utilized.
Full utilization of the expansion of the gases is
impossible from a mechanical point of view.
The expansion of the gases should be as rapid as

THE AUTOMOBILE HAND-BOOK 147

possible, as the faster the piston uncovers the
cylinder wall, the less time will be left for the
transmission of heat or energy to the cylinder wall.
Gasoline vapor or gas in themselves are not
combustible, but must be mixed with a certain
amount of air before ignition and consequent
combustion can be effecte<l. The combustion of
the gases is not instantaneous, but continues
during the entire working stroke of the motor-
piston. The extremely high temperature pro-
duced by the combustion necessitates the use of
cooling devices round the exterior of the motor
cylinder, such as air-cooling ribs or a water-
jacket — see also Explosive Motors.

Fractions of an Inch, Decimal — See Table
No. 10.

Frames — See Chassis, also Running Gears.
Frame-hangers— See Body-hangers.

French and English Units — See Kilogram,

Kilometer, Liter — ^Table No. 15.

Friction Clutches — See Power Transmission
Devices.

Friction Drive, Forms of Disk and Roller.

Since the inception of power-driven macliinerv,
one of the principal requirements has been so mo
form of speed -changing derice to suit the? varviu;^
conditions of the work. Devices for this purfKisc
are of such innumerable forms and types that it
would not be within the scope of this work to
discuss them.

148 THE AUTOMOBILE HANEX-BOOK

The oldest form of speed-changing device in
use consists of two sets of pulleys of different
diameters on parallel shafts, driven by an endless
belt. Change of speed is effected by shifting the
belt from one set of pulleys to another. Another
motluxi is by two sets of gears, arranged so that
the required pair of gears can be either slid into
mesh, or be brought together by means of an
eccentric. Taper pulleys in the form erf truncated
cones with their unlike ends adjacent on parallel
shafts and belt driven, form a third means of
variable speed transmission, the change being
effected by sliding the belt along the surface of
the cones wliile they are in motion.

In the disk and roller transmission, a roller
cnf^ages the flat surface of a dLsk, and transmits
power l)y pressure being brought to bear upon
the contact surfaces. The speed is increased or
decreased by sliding the roller along the face of
the disk l)etween the center and the edge. By
moving the roller to the right or left of the center
of the disk, the direction of motion of the roller
or the disk may l)e changed at will. If the disk
be the driver the direction of rotation of the roller
will be changed, and if the roller is driving the
direction of the rotation of the disk will be
clianged, when the roller passes from one side of
the center of the disk to the other.

The first two forms mentioned, the sets of
pulleys or gears, are only capable of changes of

THE AUTOMOBILE HAND-BOOK 149

speed in fixed ratios as 1-2-3 or 1-3-9, etc., while
the third, the twin taper pulley or cone form, will
give a gradual variation of speed, with the normal
driving speed at a halfway point in their length
if they are of similar dimensions throughout.
The disk and roller form of speed-change trans-
mission is not only capable of giving a gradual
increase or decrease of speed, but, as before
stated, by sliding the roller from one side of the
center of the disk to the other, a change in the
direction of rotation of either roller or disk may
be effected.

But the disk and roller f^rm of variable speed
transmission has an objection in the fact that the
portion of the face of the disk which is in contact
with the roller does not travel at a uniform rate
of speed throughout the length of the roller
contact. Suppose the roller were made in three
separate sections, with only line contacts or knife
edges, one inch apart, and that the radius of
travel of the center section of the roller from the
center of the disk was four inches, and for the
inner and outer sections, 3 and 5 inches respec-
tively. The travel of the center section of the
roller on the surface of the disk for one revolution
would be 25.13 inches, for the outer section
31.42 inches, and for the inner section 18.85
inches. This plainly shows that slippage must
take place during the transmission of power by
means of the disk and roller method.

150 THK AUTOMOBILE HAND-BOOK

In spite of this fact and on account of its
simplicity of construction the disk and roller form
of variable speed transmission is in use for a
great many different purposes in the mechanical
arts. Examples are small drill presses, grinding
machines and countershafts. In automobile use
it forms an ideal method of transmission with
variable speed and reverse or change of direc'tion,
without gears or belts.

While there are a great many combinations
and adaptations of the disk and roller form of
variable speed power transmission in use, they
are all l)ase(i on the three elementary forms
of construction shown in the accompanying
drawings.

The upper view in Figure 49 shows one form
of disk and roller transmission, in which the disk
forms an integral part of the motor flywheel, and
the power is transmitted to the driving wheels of
the vehicle bv suitable means from the roller
shaft. As the power to be transmitted by the
device is at all times proportional to the velocity,
in feet per minute, of the path of travel of the
roller t)n the disk, and to the pressure at the
contact between the disk and roller, it follows
that the nearer the center of the disk the roller
travels, I he less its veUxity, and the greater the
pressure renuiriHl between the disk and roller to
transmit the same power. In this tj'pe the disk
veWity is uniform and the roller speed variable.

THE AUTOMOBILE HAND-BOOK ISl

^I-

rl
V '

^I-

■^I-

U JUL U

Fig. 49 ^

152 THE AUTOMOBILE HAND-BOOK

The center view is another form of disk and
roller transmission, in which the roller is slidably
located upon the motor shaft, and the power
transmitted to the driving wheels of the vehicle,
through the medium of a countershaft carrying
the disk. With this arrangement, as the roller
speed is constant, the speed of rotation of the
disk will vary, as the roller is moved from the
center to the periphery of the disk. The same
pressure is required to transmit the same power
when the roller is at the periphery of the disk,
and the disk shaft at its slowest speed, as when
the roller is near the center of the disk, and the
disk shaft at its highest speed.

Another form of disk and roller transmission,
in which two rollers and disks are employed, is
shown in the lower view. One roller and disk
run loose. By this method twice the power can
be transmitted as in the case of the constructions
previously illustrated. Double the pressure must,
of course, be put upon the loose disk to eflFect
this increase of power. When both rollers are
at the periphery of the driving disk on the motor
flywheel, the pressure upon both rollers is alike,
as the idle roller transmits its portion of the
power tlirough the idler disk l)ack to the sliding
roller, tlms giving twice the traction of the single
roller device. When the sliding roller is moved
toward the center of the disks, the pressure from
the idler disk is increased upon the sliding roller

THE AUTOMOBILE HAND-BOOK I53

and consequently decreased upon the idle roller,
thus giving a greater tractive effort than if the
idle roller were not used. While slightly more
complicated, the advantage of this construction
over the other forms is obvious. While the
pressure upon the idler disk is doubled, the
pressure upon the contact surface of the driving
roller is the same as if only one roller were used
and but half the power transmitted.

The following formulas deduced from the
results of tests give the power which can be trans-
mitted by the constructions shown in Figure 49.

Let P be the pressure in pounds between the
contact surfaces of the disk and roller, F the
width of the face of the roller, C the coeflBcient
of adhesion or tractive effort between the contact
surfaces, N the speed in revolutions per minute,
R and L the radii as shown in the drawings, and
H.P the horsepower transmitted by the disk and
roller. Then

„^ PxFxCxNxR,^^ , ^

^^= 21:000 (Nos.land2)

„^ PXFXCXNXRXL,^,
^^= 63.000 X(R+L) (^" ^)

The values of C for different materials are given

as follows:

0.15 Cast Iron and Cast Iron.

0.18 Cast Iron and Copper.

0.25 Cast Iron and Rawhide.

0.27 Copper and Rawhide.

0.30 Rawhide and Rawhide.

154 THE AUTOMOBILE HAND-BOOK

Example: What will be the maximum and
minimum horsepower transmitted by a disk and
roller of the form illustrated in the upper view in
Figure 49, with copper-faced disk and ca^t iron
roller of 1 inch face? The contact circles on the
disk are 3 and 7h inches respectively, and the
motor speed is 900 revolutions per minute, with
100 pounds pressure at the contact surfaces.

Answer : As the coefficient of traction for cast
iron and copper is 0.18, then the minimum wnll
be : 100 X 1 X 0. 18 X 900 X 3, or 48,600, divided by
'^ 1,000, which gives 2.31 horsepower. The max-
imum will be 100X1X0.18X900X7.5, v^hich
equals 121,500, divided by 21,000, givmg 5.78
horsepower.

Example: Under the same conditions with a
roller (> inches in diameter, what horsepower will
the form of transmission illustrated in the center
view in Figure 41) transmit for minimum and
maximum disk speeds?

Answer : As the speed of the roller is constant
and the disk speed varies as the roller is moved
in or out from the center, the power transmitted
will be constant at any portion of the surface of
the disk, and will be the same as the minimum
power for the form illustrated in the above
example, that is, 2.31 horsepower. As the
leverage is increased as the roller moves out, the
speed of the disk is correspondingly decreased, or
vice versa.

THE AUTOMOBILE HAND-BOOK 155

By means of the formulas given the power
transmitted by any of the three forms illustrated
may be readily calculated for a given pressure,
speed and width of roller contact-surface.

Front Axles — See Axles.

Fuel Economy, Effect of Motor-speed on.

In a well designed gasoline motor with admission
and exhaust valves of ample proportions, a
practically full charge should be taken into the
motor cylinder at any rate of speed and the com-
pression will improve considerably at high speeds
owing to the time for leakage between the piston-
rings and cylinder wall being diminished. This
gives a decided gain in fuel economy. Above a
certain rate of speed, however, the compression
pressure will be reduced, due to the increased
friction of the gases in their passage through the
carbureter, admission-pipes and valves of the
motor. With increased motor speed less time is
allowed for the heat developed in the charge dur-
ing compression, to pass through the cylinder wall,
thus increasing the temperature and consequent
explosion pressure of the gases at the time of
their ignition. This also improves the fuel
economy of the motor.

Gases, Expansion of. All gases expand

equally, j\^ part of their volume for each degree
of temperature. Centigrade, or jj^ part of their
volume for each degree of temperature,
Fahrenheit.

156 THE AUTOMOBILE HAND-BOOK

Gas Lamps. The gas used in gas lamps is
generated by water, in minute quantities, drop-
ping on acetylene (carbide of calcium) ; the gas
thus formed passes from the generating chamber
into the body of the lamp and is consumed at
the lava tips, which are placed in front of a
highly polished mirror. The generators in
some cases are separated from the lamp itself
and placed on the dashboard or under the
hood, a rubber hose conveying the gas to the
lamp.

Gasoline Explosions. There are two entirely
different kinds of explosion, which would
undoubtedly l)oth be referred to as gasoline
explosions. The real gasoline explosion is the
kind taking place in the cylinder of a gasoline
motor, in which heat and pressure are suddenly
produced hy the combustion of gasoline vapor in
air. The other kind of explosion referred to may
be explained as follows:

If a tank of gasoline be placed on a woodpile
and the latter set on fire, the heat would raise
a pressure in the tank, which would rapidly
increase and the tank would finally explode from
the pressure. The gasoline would then be
thrown in all directions, and, ownng to its super-
heated condition, the greater part of it at least
would instantly vaporize, mix wnth the air of the
atmosphere and be ignited by the flame which
caused the explosion.

THE AUTOMOBILE HAND-BOOK 157

Gasoline Fires, Extinguishing. A number

of fires have been caused by leaky gasoline pipes
on automobiles and many persons would like
to know of chemicals which can be used to put
out such fires. Water is an exceedingly dangerous
proposition to use and it is not always possible
to get at the fire to smother it with wet rags or
waste.

In case of fire due to gasoline, use fine earth,
flour or sand on top of the burning liquid.
Never use water, it will only serve to float the
gasoline and consequently spread the flames.

A dry powder can be used for this purpose
which will extinguish the fire in a few seconds.
It is made as follows: Common salt, 15 parts^
sal-ammoniac, 15 parts — bicarbonate of soda,
20 parts. The ingredients should be thoroughly
mixed together and passed through a fine mesh
sieve to secure a homogeneous mixture.

If by any chance a tank of gasoline takes fire
at a small outlet or leak, run to the tank and
not away from it, and either blow or pat the
flame out. Never put water on burning gasoline
or oil, the gasoline or oil will float on top of the
water and the flames spread much more rapidly.
Throw fine earth, sand or flour on top of the
burning liquid. Flour is best. The best
extinguisher for a fire of this kind in a room that
may be closed, is ammonia. Several gallons of
ammonia, thrown in the room with such force as

158 THE AUTOMOBILE HAND-BOOK

to break the bottles which contain it, will soon
smother the strongest fire if the room be kept
closed.

Gasoline, How Obtained. Benzine, Gasoline,
Kerosene and the kindred hydro-carbons are
products of crude petroleum.

They are separated from the crude oil by a
process of distillation. The process is very
similar to that of generating steam from water.

Crude petroleum subjected to heat will give oflf
in the form of vapor such products as Benzine,
Gasoline and Kerosene, etc. The degrees of
heat at which these products are separated are
comparatively low. Various degrees of heat will
separate the distinct products. As a means of
illustration, it may be said that the crude oil when
raised to certain temperatures gives oflF vapors
which when cooled liquefy into what are known
as Benzine, Gasoline and Kerosene.

Gasoline Motors — See Explosive Motors.

Gasoline, Not Dangerous. A lighted match
placed at the opening of a new 2-gallon can of
gasoline merely caused a small flame an inch
long, which could be extinguished with the point
of a finger.

Gasoline was poured into an open vessel and a
lighted cigarette dropped into it. Result: It
was at once extinguished.

A lighted cigarette was smoked vigorously from
within two feet above to a quarter of an inch of

THE AUTOMOBILE HAND-BOOK 150

the gasoline — also all around and underneath the
vessel, but no ignition occurred.

A small quantity of gasoline was poured on a
cigarette while smoking — still no ignition occurred.

A can was then made hot, and the gasoline
poured into it, so that it would vaporize more
quickly — a lighted cigarette was then smoked into
it, as in the third case, but failed to cause
ignition.

Gasoline Tanks — See Tanks.

Gasoline Motor Gonstraction. Wlien design-
ing a gasoline automobile motor, the first question
that will arise is as to the pro[)er number of
cylinders. The question as to the proper number
of cylinders for an explosive motor may be briefly
summed up as follows: A single cylinder has
the merit of simplicity, and requires less mechan-
ism to operate it, but tends towards excessive
vibration. Multi-cylinders develop more power
with less weight and reduce the motor vibration
and strain, and have also other advantages over a
single cylinder. The question therefore is : How
many cylinders are best in practice? To give the
best results, a two-cylinder motor should, if the
cranks are opposed, have its cylinders in axial
alignment in order to ensure a uniform impulse.
If the cranks and cylinders are (jpposed it is
possible to obtain correct mechanical balance of
connecting rods and pistons, and vibration Ls thus
diminished. If the cylinders arc of the twin form

16;) THE AUTOMOBILK HAND-BOOK

with the cranks opposed, explosion =? will nec-
essarily follow each other at a half revolution,
and one and a hal? revolutions apart. This gives
irregular impulses which tend to set up vibration.
The next best construction is three cylinders,
with the cylinders parallel, and the cranks set at
an angle of 1'20 degrees. This gives regular
impulses two-thirds of a revolution apart, and
consequently a more uniform strain on the parts,
and reduces vil)rati()n.

A four-cylinder motor has greater advantages
of mechanical balance than the three-cylinder
form, but on the other hand, by reason of the
greater amount of exposed cylinder wall for a
given capacity, it is not as economical in fuel
consumption. The greater advantage of four as
compared with tlie three cyHnders, is a greater
division of the inij)ulses, reducing vibration to a
minimum.

Other points to be considered in the design of
a motor are:

File pro])cr arrangement or location of all
working parts so as to be rc^adily accessible for
repair or adjustment.

Practicallv automatic lui>ricati()n of the motor.

■

The best and simplest method of operating the
admission antl exhaust-vahes.

The propcT diameter and weight of flywheel
and a ])racti('ally correct I)ahince of the recipro-
cating parts of the motor.

THE AUTOMOBILE HANU-BOOK

nt-

r^l ? 1

12^

^^j^riy"

10_

■^C

31 ft=^

4 v^

8-^M

^ XJ

6^-^ 1

Fig. 50

Vertical Cylisdei

, WATEIt-t

uuLKii Gasoline MoTim.

0. Crank case.

a. Cyllntu.r.'* ''

The best and most reliable sy.slcm of ignition,
with a view to eliminating ignitiiin troubles.

The most economical type of carbureter and
one that will require the lea.-it attention.

162 THE AUTOMOBILE HAND-BOOK

And last, but not least, reduction of weight,
simplicity of construction and good mechanical
design.

In the construction of motor cylinders ex-
perience has clearly established one point — that
the cylinder, with its combustion and valve-
chambers, should be integral or in one piece, and
that no joints closed by gaskets should exist back
of the head of the piston. While all manu-
facturers do not adhere to this rule, it is a fact
that many difficulties have been experienced with
leaky joints, and that the plan of avoiding them
altogether should be followed.

Figure 50 shows a vertical cross-section of a
gasoline automobile motor of the most approved
mcxlcrn type. It has automatic lubrication,
detachable inlet or admission-valve and rotary
pump for the water circulating system.

Figure 51 illustrates a modern type of vertical
four-cylinder gasoline automobile motor, having
the admission-valves automatically throttled by
means of a centrifugal governor on the end of
the cam-shaft, as shown in the drawing- The
admission- valves are mechanically op>erated.

Wfiile the cooling of the cylinder of an explo-
sive motor is most successfully accomplished by
means of a water-circulating system, a number of
up-to-date cars successfully use cooling devices
other than water. The success of air cooling for
explosive motors is due in most cases to the use

THE AUTOMOBILE HAND-BOOK

of a number of ribs ca.st integml with tho cylinder
and having a largo radiating surface.

Figure 52 shows a form of vertical air-cooled
motor with radiating ribs cast around the cylinder
and valve-chamber. The motor has a detachable,
atmospherically operated admission -valve, without

Veiitical Fouh-c-ylisdeh Motor
Witli meclianically operaterl atiniissi on -valves with auto-
matic tlirottliiig povenior.

packing. The valve and cage may be removed
by simply removing two nuts — see Explosive
Motors, also Four-cycle Motor.

Gasoline Motor, Fuel Consumption of. The
fuel consumption of a motor is always a serious
question, and one of importance to the purchaser
as well as to the manufacturer.

164 THE AUTOMOBII-E HAND-BOOK

AIR-COOLED MOTOR

THE AUTOMOBILE HAND-BOOK 165

Ordinarily about one and two-tenths pints of
gasoline per horsepower hour under full load
will cover the fuel consumption. That is, when
the mixture is of the proper explosive quality and
the water comes from the jacket at a temperature
of about 160 degrees Fahrenheit.

The temperature of the water in the jacket
around the cylinder has a great deal to do with
the fuel consumption.

If the water is forced around the cylinder so
as to keep it cold, the heat from the combustion
is cooled down so quickly by radiation that the
expansive force of the burning gases is materially
reduced, and consequently less power is given up
by the motor.

The object of the water is not to keep the
cylinder cold, but simply cool enough to prevent
the lubricating oil from burning. The hotter the
cylinder with effective lubrication the more power
the motor will develop.

It should be remembered that a hot motor is
the most economical in fuel.

Gasoline, Thermo-dynamic Properties of

Gasoline and Air. The following table. No. 12,
gives the thermo-dynamic properties of gasoline
and air and may be of interest, in view of the
fact that information on this subject is sparse and
most of that only theoretical or empirical
deductions.

This table gives the explosive force in pounds

166 THE AUTOMOBILE HAND-BOOK

per square inch of mixtures of gasoline vapor and
air, varying from 1 to 13 down to 1 to 4, also the
lapse of time between the point of ignition and
the highest pressure in pounds per square inch
attained by the expanding charge of mixture.
The tests from which the results given were
obtained, were made with a charge of mixture at
atmospheric pressure, so as to more accurately
note the results, as the mixture takes much
longer after ignition to attain its highest pressure,
and is slower also in expanding.

It may be well to remember that there are no
more heal-units, and consequently no more foot-
pounds of work in a mixture of gasoline and air,
under 5 atmospheres compression, than under 1
atmosphere compression.

Flanged or ribbed air-cooled motors will ap-
proach the figures given in the table for the initial
exj)losive force for the varying compressions , very
closely, while thermal-syphon water-cooled motors
will come within about 20 per cent of these results,
and pump and radiating coil cooled motors will
come within about 30 per cent. While it appears
at the first glance that the proper thing to do to
get the greatest efficiency from a motor would be
to let it run as hot as possible, experience has
shown that the repair bill of a hot motor will
more than offset its efficiency over the cooler
water-jacketed motor, with pump and radiating
coils. The last two columns in the table give

THE AUTOMOBILE HAND-BOOK

167

the temperature of the burning gases, the first of
the two columns the actual temperature with the
accompanying mixture of gasoline and air, and
the second the theoretical temperatures, or tem-
perature to which the burning mixture should
attain, if there were no heat losses.

Table No. 12.
Thermo-dynamic Properties of Gasoline and Air.

Gasoline,

Vapor and

Air.

Time in
Seconds
between
Ignition

and
Highest

Pres-
sure.*

Explosive Force in
Pounds per sq. in.

Compression
In Atmospheres.

Temperature

of Combustion

in Degrees

Fahrenheit.*

Actual.

Theo-
retical.

1 to 13
1 to 11
1 to 9
1 to 7
1 to 5
1 to 4

0.28
0.18
0.13
0.07
0.05
0.07

156
183
234
261
270
240

208
244
312
348
360
320

260
305
390
435
450
400

1857
2196
2803
3119
3226
2965

3542
4010
4806
6001
6854
5517

♦ At atmospheric pressure.

Gear, Change-speed — See Power Transmission
Devices.

Gears, Diametral Pitch System of. Table

No. 13 gives the necessary dimensions for laying
out and cutting involute tooth spur gears from
No. 16 to No. 1 diametral pitch. Formulas are
also given so that if the number of teeth and the
diametral pitch are known, the pitch diameter
can be ascertained — also, the diametral pitch,

168 THE AUTOMOBILE HAND-BOOK

outside diameter, number of teeth, working depth,
and clearance at bottom of tooth:

P = Pitch diameter in inches.

D — Diametral pitch.

W= Working depth of tooth in inches.

T = Thickness of tooth in inches.

O = Outside diameter in inches.

C = Circular pitch in inches.

(1) Pitch diameter =^

(2) Outside diameter=P-f

(3) Diametral pitch =p

(4) Circular pitch= '

(5) Working depth of tooth=^=2-^D

((]) Number of teeth=P X D

(7) Thickness of tooth= 1.571 X D

(8) Clearance at bottom of tooth =^7:
^ 20

For example: Required, the pitch diameter of
a gear with 20 teeth and No. 5 diametral pitch.
From Formula No. 1, as the pitch diameter is
equal to the number of teeth divided by the
diametral pitch, then 20 divided by 5 equab 4, as
the required pitch diameter in inches.

What is the outside diameter of the same gear?

THE AUTOMOBILE HAND-BOOK

169

From Formula No. 2, as the pitch diameter is
4 inches, and the diametral pitch No. 5, then 4
plus § equals 4f as the proper outside diameter
for the gear.

What would be the diametral pitch of a
gear with 30 teeth and 5 inches pitch diam-
eter? From Formula No. 3, 30 divided by 5
equals 6, as the diametral pitch to be used
for the gear. In this manner by the use of the
proper formula any desired dimension may be
obtained.

Table No. 13.
Dimensions of Involute Tooth Spur Gears.

Diametral
Pitch.

Circular
Pitch.

3.142
1.571
1.047
0.785
0.628
0.524
0.447
0.393
0.314
0.262
0.224
0.196

Width of

Tooth on

Pitch

Liue.

1.571
0.785
0.524
0.393
0.314
0.262

0.224
0.196
0.157
0.131
0.112
0.098

Working

Depth of

Tooth.

2.000
1.000
0.667
0.500
0.400
0.333
0.286
0.250
0.200
0.167
0.143
0.125

Actual

Depth of

Tooth.

2.157
1.078
0.719
0.539
0.431
0.360
0.308
0.270
0.216
0.180
0.154
0.135

Clear-
ance at
Bottom
of Tooth.

0.157
0.078
0.052
0.039
0.031
0.026
0.022
0.019
0.016
0.013
0.011
0.009

Gear, Differential — See Power Transmission
Devices.

Gears, Horsepower Transmitted by. The

following formulas will give the horsepower that

170 THE AUTOMOBILE HAND-BOOK

may be transmitted by gears with cut teeth of
involute form and of various metals.
H.P = Horsepower.

P=^ Pitch diameter in inches.

C= Circular pitch in inches.*

F= Width of face in inches.

R= Revolutions per minute.

^ PXCXFXll
H.P= — (Annealed tool steel.) (1)

.... P X C X F X R (Mach. steel or Phos-

H.P= (2)

140 phor Bronze.) ^

PXCXFXR
U.V= - - (Cast Brass.) (3)

PX( XFXR ,
H.P= —- (Ca^tlron.) (4)

Exai.i;)le: lle(juired, the horsepower which
a tool steel pinion, "2 inches pitch diameter, 1
inch face and No. 10 diametral pitch, will trans-
mit at 900 revolutions per minute.

Answer: From the table the circular pitch
corresponding to No. 10 diametral pitch is 0.314.
Then bv Formula No. 1, •2X0.314X1X900
c(|uals 5i)5.''Z. This, divided by 90, gives 5.29
horsepower.

*The ciri'ular i)iti*h I'orrosiKnidliijr to any diametral pitch
iminbcr. may bo found by dividinjj: thefoustaut 3.1410 by the diam-
etral pitch.

Kxtiniple : What is i he oircuhir pitch in inches correspoudlnjc
to No. G diametral pitch y

Answer: The result of di^idinK 3.1416hy 6Klves O.MMlllcheif
as the reciuired circular pitch.

THE AUTOMOBILE HAND-BOOK

171

Fig. 53

Gear, Intemal-epicyclic. It is often desired

to ascertain the speed of rotation of the different
members of this form
of gearing. To cal-
culate their speeds,
the following formulas
are given, which, by
reference to the letters
designating the differ-
ent parts in Figure
53, may be readily
solved.

INTERNAL GEAR

Let R be the revolutions per minute of the disk
or spider carrying the pinions D.

Let N be revolutions per minute of the gear E.

Let G be the revolutions per minute of the
internal gear F.

When the internal gear F is locked and gear E
rotating, the speed in revolutions per minute of
the disk or spider carrying the pinions D is

If the internal gear be locked and the spider
carrying the pinions D be rotated , then the speed
in revolutions per minute for the gear E will be

E+F\
E )

If the spider carrying the pinions D be held
rigid and the gear E be rotated, the speed in

R=N|

n=r(J

172 THE AUTOMOBILE HAND-BOOK

revolutions per minute for the internal gear F is

• ^ NXE

If the pitch diameter of the gears is not readily
obtainable, the number of teeth in each gear maybe
used instead, as the result will be exactly the slime.

Generator. This term is usually applied to
any form of chemical or mechanical energy which
can be used to produce a current of electricity.
Mechanical generators of electricity used for
ignition purposes are of two forms, dynamos or
magnetos. The former is self-exciting by means
of coils of wire wound upon the magnet limbs.
The latter has permanent magnets instead of
coils of wire to induce the current in the armature
of the magneto. Magnetos, on account of their
simplicity of construction and low first cost, are
more generally used for ignition purposes than
dynamos. They may be operated by the motor
with a friction-pulley, gear or belt. Figure 54
shows one form of a magneto arranged to be
operated by the friction pulley on the left-hand
end of the armature shaft.

The simplest form of magneto and the one
shown in Figure 54 consists of two or more mag-
nets of horse-shoe shape, the ends of which
embrace the pole-pieces, between which rotates a
shuttle armature wound with small insulated cop-
per wire. Rotation of the armature of the magneto
tends to disturb the path of the lines of force or

THE AUTOMOBILE HAND-BOOK

magnetic flux flowing between the ends of the per-
manent magnets, which in turn set up powerful
induced currents in the armature. The current
produced by the magneto is of an alternating

(f%

MAGNETO

nature, but converted into a direct or continuous
current by means of the commutator on the
armature shaft.

Governor, Use of. All explosive motors when
ranning under a heavy load slow down or reduce
their speed very materially. If the load be
entirely or partially removed from the motor very
suddenly, it will tend to race. This racing,
which ca'ises excessive wear and vibration, is
very injurious to the motor. On light cars with
small-powered motors, racing is usually prevented
by some form of hand control, such as retarding
the ignition or throttling the mixture supply. On
heavy, high-powered automobiles, racing of the
motor is eliminated by the use of some form of cen-
trifugal governor, which controls the motor-speed

THE AUTOMOBILE HAND-BOOK

ly one of the three following methods: Retarding
the ignition — Throttling the supply of mixture —
Preventing the exhaust-valve from opening.

Figure 55 shows a form of governor which
operates by preventing the exhaust-valve from
opening. When
the speed of the
motor passes its
normal limit, the
balls A of the
governor move
out towards the
periphery of the
gear or wheel
which carries
them, causing
the cam B to be
moved to the rigiit by the action of the d(^ on
the governor arms, which engage in a grooved
collar on the sleeve C.

The nose of the cam B is thus kept out of
engagement with the roller D until the motor
resumes its normal speed, thus preventing the
valve-lifter from opening the valve.

Normally the cam is held in position by the
springs attached to tlie governor balls, against
the shoulder of the bearing F, which carries the
cam shaft G.

Grades, Power Required to Climb. Table
No. 14 gives the approximate horsepower required

GOVERNOR

THE AUTOMOBILE HAND-BOOK 178

to move a vehicle with a total load of 1,000
pounds, at varying speeds.

HoHSBPOWER Required to

E A

Vehicle

Weighing 1000 PonNoa.

■S

Speed In Miles per Hour.

S 110

1.3

r^c

2.6

3.0

3.4

3.8

4.3

4.S

5.2

5.G

6.0

6.5

1,4

1.9 2.4

3.3

3.8

4.3

4.8

5.3

5.8

6.3

6.7

7.2

1.8

2.3 2.9

3.5

4.1

4.7

S.3

6.4

7.0

7.6

8.2

8.7

2.1

2.7 3.5

4.2

4.8

5.5

9.2

e.o

7.6

8.4

9.0

9.6

10.4

2.4

3.2 4.0

4.8

5.6

6.4

7.2

8.0

S.8

9.6

10.4

11.2|12,0

2.8

3.6 4.5

5.4

6.3

7.2

S.l

9.0

lO.C

10.8

11.7

12.613.5

3.1

4.15.0

6.1

7.1

8,1

9.1

10.1

12.3

13.1

14.1 15.1

3.4

4.5'5.5

6.7

7.8

9.0

10.1

n.o

i2'l

13.5

14,5

16.616,5

3.7

4.9|e.l7.4

8.6

..s

11. 1

12,2

13.5

14.8

15,9

17.2 18.3

Gravity, Acceleration of. Weight is the force
apparent when gravity act.s upon mass. Mass is
matter wilhout reference to weight. When mass
or matter is prevented from moving under the
stress of gravity, its weight can be appreciated.

V = Velocity in feet per second

( =Time in seconds

h = Height in feet

9 —gravity constant— 32.2

ft="-i

■v= Vi.g.h
2.k

-m)

176 THE AUTOMOBILE HAND-BOOK

Weight does not enter into consideration in the
above formulas. In a perfect vacuum a feather
should fall from a given height in the same time
that a pound weight would.

Grease Cups — See Lubricators.

High-tension Current — See Electrical Ignition
and Induction Coil, also Secondary Current.

Historical Facts. 1803— Principle of the
storage battery discovered by Bitter.

1813 — Hedley demonstrated by ex[>erinient, in
England, that traction on rails was possible.

1820 — Ampere developed the fundamental laws
of electro-dynamics.

1821 — Michael Faraday caused a wire carrjdng
an electric current to rotate around a permanent
magnet. This was the inception of an electric
motor.

1823 — The difiFerential-gear movement first
invented for use in roving frames by Asa Arnold.

1824 — Sturgeon discovered the electro-mag-
net.

1827 — First drop-forging made at Ebrper's
Ferry by J. H. Hall.

1828 — Malleable iron discovered by Seth Boyd.

1830 — Crucible cast steel first made successfully
at Cincinnati Steel Works.

1833 — First electric motor made in this country
by Saxton.

1834 — Prof. Henry made a practical working
electric motor.

THE AUTOMOBILE HAND-BOOK 177

1838 — First two-cycle gas motor patented in
England by William Barnett.

1851 — Rumkorff invented the jump-spark coil.

1853 — First steam motor carriage made in this
country by J. K. Fisher, New York.

1859 — First practical storage battery made in
France by Gaston Plante. Petroleum discovered
in United States.

1862 — Beau de Rochas first formulated the
four-cycle gas motor as afterward built by Pro-
fessor Otto.

1876 — First practical gas motor by Professor
Otto in Germany.

1881 — Faure type of storage battery first made,
now almost exclusively used.

1888 — Gasoline first used in a gas motor by
Van Duzen of Cincinnati.

Hoods — See Bodies.

Horsepower, of Explosive Motors. A horse-
power is the rate of work or energy expended in
raising a weight of 550 pounds one foot in one
second, or raising 33,000 pounds one foot in one
minute. This is far more work than the average
horse can do for any great length of time. A good
horse for a short period of time can do much more.

As the ordinary formula used for the calculation
of horsepower in connection with steam engines is
not directly applicable to explosive motor practice,
formulas are here given that are more suited to
the purpose.

178 THE AUTOMOBILE HAND-BOOK

Let D be the diameter of the cylinder in inches,
and S the stroke of the piston also in inches ; if N
be the number of revolutions per minute of the
motor, and H.P the required horsepower of the
motor, then for a four-cycle motor

D'XSXN
18,000

Example: What horsepower should be
developed by a motor of 4j inches bore and
stroke, at a speed of 1,200 revolutions per minute?

Answer: As the bore and stroke of the motor
are alike, the square of the bore multiplied by
the stroke is equal to the cube of 4 J, which is
91.125, this multiplied by 1,200, and divided by
18,000, gives 6.08 as the horsepower of the
motor.

From a theoretical standpoint a two-cycle
explosive motor should not only have as great
a speed but also be capable of developing almost
twice the power that a four-cycle motor does.
It is a fact nevertheless that its actual performance
is far different.

The horsepower of a two-cycle motor may be
calculated from the following formula,

^^'^ 21,000

Example: Required, the horsepower of a two-
cycle motor of 4V inches bore and stroke, with a
speed of 900 revolutions per minute?

THE AUTOMOBILE HAND-BOOK 179

Answer: The square of the bore multiplied
by the stroke b equal to 91.125, which multiplied
by 900, and divided by 21,000, gives 3.91 as the
required horsepower. The results given by the
above examples agree very closely with those
obtained from actual practice.

Habs, Ball and Plain-bearing. 'The result
of experiment shows that the starting friction of

BALL BEARING HUB

wheel hubs fitted with ball-bearings is far less
than that of the most improved design of plain-
bearing hubs. Some of the objections to the
more extended use of ballbearings on auto-
mobiles are as follows: The concentration of
the load on a very small surface — The friction

180 THE AUTOMOBILE HAND-BOOK

between the rollers themselves — The need of fre-
quent adjustment. Plain-bearing hubs, while
giving somewhat more friction than ball-bearing
hubs, require little or no attention, are less in
first cost and less liable to injiuy from road
shocks or jars.

Figure 56 shows a ball-bearing hub ot neat
design and compact form, which is extensively
used on motor cars of European make. The hi^

Fre, 57

PLAIN BEARING HUB

proper ant] the removable flange are of cast steel.
while the end cap or cover is of bronze with a hex-
agon for removing or replacing the cap. The
grooves or ball races are of rounded form instead
of the usual two-point bearing cup.

A pkin-bcaring hub is shown in Figure 57,

THE AUTOMOBILE HAND-BOOK 181

fitted with removable bronze bushings, which
may be easily replaced when worn. The space
in the center of the hub between the bushings is
filled with oil or grease for the purpose of lubri-
cating the spindle of the axle.

The length of the axle-spindle embraced by the
bearing should not be less than one-fourth of the
wheel diameter.

If the axle-spindle be taper, the large diameter
should not be less than that of the axle proper.

An axle-spindle equal in diameter to an axle
proper of square section, has only 60 per cent of
its strength or carrying capacity. A generous
fillet should always be left on the axle-spindle
next to the flange or collar of the axle.

Ignition, Catalytic. This method of ignition
for explosive motors is based on the property
possessed by spongy platinum of becoming incan-
descent when in contact with coal gas or carbu-
reted air. With this means of ignition, speed
regulation or variation can only be had within
very narrow limits. The principal objections to
its extended use are danger of premature ignition,
lack of speed control and difficulty of starting the
motor.

Ignition Circuit. Diagram No. 5 illustrates
the ignition circuit of a single cylinder motor,
showing plainly the battery, coil and commutator
connections. A reference table accompanies
Diagram No. 5, giving the names of the van-

THE AUTOMOBILE HAND-BOOK

ous parts shown in the drawing of the ignition
circuit.

DIAGRAM

IGNITION CIRCUIT

1— Dntten-.

-Condenser,

3 aiiLl a-Priraary «liv-.

u-Commulaior.

l-Vlliriitor.

l-Ckmtact loaker.

a-CommutftUir case.

«-Crank luse.

7-Cylli«ler.

1 and I!)— Secnnilary vires.

8-In<lu.-rlou .-.111.

fl-Spark pli-B.

IgoitiOQ Devices. The device illustrated in
Figure 58 consists of a magneto, having a sbuUle

THE AUTOMOBILE HAND-BOOK

183

Fig. 58

IGNITION DEVICE,

type of armature, which oscillates instead of
rotating as is usual in other forms of magnetos.
In the space be-
tween the arma-
ture and pole-
pieces a shield
or tube of soft
steel is placed,
as shown in the
drawing. To one
end of this shield
a crank is at-
tached, which is
operated by a
connecting rod
from a crank-pin on the cam-shaft of the motor.
When the shield or tube is oscillated very rapidly,
a current of electricity is induced or created in the
wire which composes the winding of the shuttle
armature.

Tliis induced current is led by means of an
insulated wire to the make and break device in
the combustion chamber of the motor, the other
wire being grounded on the frame of the magneto.
When the proper time arrives for firing the
charge the rod drops into the notch in the cam
and the projection upon its upper end strikes
suddenly upon the outer end of the contact-arm,
causing the electrical circuit to be suddenly broken.
At the same time the shield or tube is in the

184 THE AUTOMOBILE HAND-BOOK

proper position to cause the maximum current to
flow in the winding of the armature coil. No
battery or coil is required with this form of
ignition. Another form of ignition mechanism
has a magneto driven by gearing from the cam-
shaft of the motor. The armature terminals of
the magneto are connected to two collecting-rings
(not a commutator), so that the current given to
the induction coil is of an alternating kind, but
tlie electrical circuit is only broken when the
alternating current is at its maximum value.

Ignition, Effects of Advancing and Retard-
ing. It should be remembered that ignition
timing Ls not the same thing as ignition govern-
ing, therefore to obtain the best results from an
explosive motor the charge should be ignited at
the best possible moment.

With too early ignition the pressure upon the
piston becomes excessive and without any
adequate return of useful woric or energy. It the
ignition be retarded too much, the maximum
explosive pressure occurs too late during the work-
ing or power stroke of the piston and the com-
bustion of the gases is not complete when the
exhaust-valve opens. Greater motor speed re-
quires an early ignition of the charge, but greater
power calls for late or retarded ignition.

The reason for advancing the spark when fast
running is required, is that the explosion or
ignition of the charge is not instantaneous as may

THE AUTOMOBILE HAND-BOOK 185

be supposed, but requires a brief interval of time
for its completion.

When running a motor with the ignition
retarded, the mixture should be throttled as much
as possible, otherwise the motor will overheat.

When to Retard the Ignition. Always
retard the ignition before starting the motor, and
take great care that the ignition is retarded and
not by mistake advanced. Some cars are fitted
with a device which prevents the starting crank
being turned unless the spark is retarded. If it
is not clear as to which way to move the ignition
lever, to retard the ignition, move the commutator
in the same direction as the cam-shaft rotates.

As soon as the motor slows a little when going
uphill, retarding the spark enables more power
to be obtained from the motor at the slow speed,
that is to say, if the spark is not retarded the
motor will go slower than if it is retarded. Do
not retard the lever to the utmost under these
conditions, on the contrary, retard the lever to
such a point that the knocking (due to the wrong
position) ceases.

Retarding the spark causes the maximum pres-
sure of the explosion to occur at the best part of
the stroke, or, rather, the mean pressure of the
explosion stroke will be lower, if the best point of
ignition by retarding is not found. This is a
matter of some skill and practice.

To slow the motor, cut oflF as much mixture as

186 THE AUTOMOBILE HAND-BOOK

the throttle allows, then slow the motor still
further by retarding the spark, but on no account
retard the spark when the throttle is full open
(for the purpose of slowing the mptor), as the
motor will merely discharge a quantity of flame
at a white heat over the stem of the exhaust valve,
burning it, softening it, and making it scale. ^

Ignition, Electric. Any form of electrical
ignition requires some outside source of electric
energy such as a generator or battery to produce
a spark in the combustion chamber of the motor.
A primary or secondary induction coil is necessary
in connection with the source of electric energy
to give a spark of sufficient intensity to properly
ignite the compressed charge in the combustion
chamber of the motor. This method of ignition
provides a means of varying the motor speed
throughout a great range of speeds by advancing
and retarding the point of ignition, or time of
igniting the explosive charge — see Electrical"
Ignition.

Ignition, Hot Tube. The incandescent tube
system of ignition consists of a tube of metal or
porcelain, one end of which is closed and the
other screwed or fastened into the combustion
chamber bv suitable means.

The flame of a Bunsen burner is projected
against the tube, rendering it incandescent,
resulting in the firing of the compressed chaige
slightly before the end of the compressicm stroke.

THE AUTOMOBILE HAND-BOOK 187

This form of ignition has not obtained in auto-
mobile practice for several reasons, some of which
are here briefly stated. It causes misfiring of
the charge on account of either burned or partially
consumed gases filling the tube. Again, the tube
may be clogged with dead or burned gases almost
its entire length, causing premature ignition of the
fresh charge of gas in the tube on account of its
being too close to the combustion chamber. An
almost entire absence of speed regulation of the
motor, as the gases require a certain degree of
compression to insure proper ignition. Throttling
of the charge to obtain a variation in the speed of
the motor is therefore almost prohibitive or can
only be used within very close limitations.

Ignition, Reason for Advancing Point of.

It may be well to explain without entering into
theoretical details, that when a motor is running
at normal speed,, the ignition-device is so set that
ignition takes place before the piston reaches the
end of its stroke. The later the ignition takes
place the slower the speed of the motor and
consequently the less power it will develop. If,
however, in starting the motor the ignition-device
were set to operate before the piston reached the
end of its stroke, backfiring would result, result-
ing in a reversal of the operation of the motor
and possibly in injury to the operator.

Ignition Troubles, Causes of. Trouble may
occur, fcom the cam or. commutator not being

188 THE AUTOMOBILE HAND-BOOK

properly adjusted. The contact-screw of the
induction coil vibrator may be loose.

The vibrator or trembler of the coil may not be
properly adjusted.

To adjust the vibrator, turn the motor crank
until the contact is closed, throw in the switch and
listen for a good clear buzz from the vibrator.
Do not allow it to buzz slowly but fast, until it
makes a singing sound like a bumble bee, then
turn the crank several times and again listen for
the buzz. Sometimes the vibrator will buzz, but
it will not buzz when the motor is running fast
and the motor misfires ; this is probably due to the
fact that the adjusting screw has made the tension
of the spring too strong and when a quick contact
is made it does not have time to vibrate properly.
Experience is the only teacher for properly
adjusting the vibrator of an induction coil.

Many troubles arise from faulty or defective
insulation.

A wire placed too close to an exhaust-pipe
invariably fails after a time, owing to the insu-
lation becoming burnt by the heat of the pipe.

A loose mre hanging against a sharp edge will
invariably chafe through in course of time.

If the insulation of the coil breaks down it can-
not be repaired on the road, it should be returned
to the makers. A slight ticking is usually audible
inside the coil when this occurs.

All wires where joined together should be

THE AUTOMOBILE HAND-BOOK 189

carefully soldered, the joints being afterwards
insulated with rubber or prepared tapes. Never
make a joint in the secondary wires. See that
all terminals are tightly screwed up. When con-
necting insulated wire, the insulation must be
removed, so that only the bare wire is attached.
Wires sometimes become broken, and being loose
make only a partial contact.

Battery terminals frequently become corroded,
they should be covered with vaseline, and require
periodical cleaning. See that all connections at
the battery are clean and bright.

The porcelain of the spark plug may be cracked
and the current jumping across the fracture.
The points may be sooty and require cleaning.
They may be touching and require separating, or
they may be too far apart. The usual distance
between the points is about one thirty-second of
an inch, which is approximately the thickness of
a heavy business card.

Clean all oil and dirt from the commutator.
Most commutators are so placed as to give the
maximum possible opportunity to collect oil and
dirt. They should always be provided with a
cover.

In course of time dry or storage batteries
will become weak or discharged. Always carry
an extra set.

Spanners, oil-cans, tire-pumps, etc., have been
known to get on the top of the batteries, thereby

190 THE AUTOMOBILE HAND-BOOK

connecting the tenninals together and causing a
short-circuit.

The platinum contacts of the coil may become
corroded. They should be cleaned with a small
piece of emery cloth or sandpaper.

The platinum points on the trembler may
become loose. They should be riveted up with
a small hammer.

It frequently happens that oil and dirt accumu-
late on the platinum contacts, which interrupt the
free flow of the current. Care should be taken,
therefore, that they are always perfectly clean. ^-

Indicator Diagrams. The thermal or heat
efficiency of an explosive motor may be deter-
mined from an indicator diagram, which gives a
representation of the internal conditions through-
out the entire cycle of operations. The diagram
tells many tilings essential to be known.

It gives the initial explosive pressure, or
the pressure a moment after ignition has taken
place. It shows whether the volume of the
charge is diminished during the period of admis-
sion. It gives the point of ignition, when the
ignition is complete and when expansion begins.
It indicates the pressure of expansion during the
working stroke. It gives the terminal pressure
when the exhaust is opened. It shows the
rapidity of the exhaust. It indicates the back-
pressure on the piston, due to the exhaust. It
shows the point of opening of the exhaust It

THE AUTOMOBILE HAND-BOOK igi

gives the mean power used in driving the motor.
It also indicates any leakage of valves or piston.

The usual method of ascertaining the area of
an indicator diagram is by means of an instru-
ment known as a planimeter, which is used to
calculate the area of any irregular surface, by
moving a tracing point attached to the instrument
over the entire irregular boundary line of the
figure.

But for the purpose of ascertaining the horse-
power of a motor it will be sufficiently accurate to
illustrate the principles involved, to calculate the
area of the diagram by means of ordinates or
vertical measurements.

The upper drawing in Diagram No. 6 repre-
sents a card taken from a motor of 4 inches bore
and 6 inches stroke, with a speed of 900 revolu-
tions per minute, and under a full load. The
diagram is divided into 12 parts as shown by
vertical lines, the lengths of which are in terms
of the spring, which is 100. Then 1.90+1.36+
1.00, etc., divided by 12, equals 0.665 as the
average height of the diagram. Its length is 6
inches, as shown, therefore the area of the card
is approximately 3.99 square inches. As the
initial explosive force from the diagram is 250
pounds per square inch, and a 100 indicator
spring used, the height of the card is 250 divided
by 100, which equals 2^ inches as the height of
the card. The mean effective pressure on the

192

THE AUTOMOBILE HAND-BOOK

piston in pounds per square inch will therefore he
equal to the area of the diagram 3.99, divided by
the area of the whole card, which is 2jX 6, equals
15, and multiplied by 250, the initial explosive

INDICATOR DIAGRAMS

force, or 3.99 X ^250, and divided by 15, equals 66.5
pounds per square inch as the mean effective
pressure required.

From this the indicated horsepower of the motor
can readily be found as follows:

Let M.P be the mean effective pressure in
pounds per square inch, A the area of the cylinder
in square inches, S the stroke of the piston in

THE AUTOMOBILE HAND-BOOK 193

inches, N the number of explosions per minute,
and H.P the indicated horsepower, then

M.PXAXSXN

H.P=

396,000
66.5X12.56X6X450

5.69

396,000

as the required indicated horsepower of the motor.
The indicated horsepower of any motor will
always be greater than that obtained from a
brake test, as it simply represents the actual
thermo-dynamic (heat-pressure) conditions within
the cylinder, and takes no account of friction and
other external losses.

The lower drawing in Diagram No. 6 is a card
taken from the same motor running under half
load.

Indicator, Use of the. An indicator consists
of a cylinder within which works a piston under
the tension of a helical spring of predetermined
strength. The rod attached to the piston carries
a pivoted arm which works on a horizontal lever.
This lever carries a pencil bearing against a
drum. This drum is so arranged with a spring
that it may be partially rotated by the pull on an
attached string. A sheet of paper is wound on
the drum and held in place by spring clips. The
pressure in the cylinder acting on the spring
causes the pencil to mark the paper, the indicator
card or diagram being traced by the forward and
backward movement of the drum.

194 THE AUTOMOBILE HAND-BOOK

The most suitable indicator for explosive
motors is the McInneS-Dobie. It is fitted with a
device which takes a continuous record by means
of a rotating drum. Another device is the mirror-
indicator of Hospitalier.

Induction Coil. The form of coil generally
used on gasoline cars is known as the jump-spark
coil. It is of two types, one known as a plain or
single jump-spark, the other as a vibrator or
trembler coil.

A jump-spark coil consists essentially of a
bundle of soft iron wire, known as the core, over
which are wound several layers of coarse or
large size insulated copper wire, called the primary
winding. Over this are again wound a great many
thousand turns of very fine or small wire, known
as the secondary winding — see also Electrical
Ignition.

Inlet-pipe — See Admission-pipes.

Inlet-valve — See Admission-valves.

Inner Tubes— See Tires.

Insulating Material. Asbestos, lava, and
mica arc severally used for the insulation of spark
plugs and sparking devices.

Vulcanized fiber or hard rubber or even hard
wood are used for the bases of switches, con-
nection boards, etc.

India rubber or gutta-percha form the basis of
the insulated covering of wires used for electrical
purposes. The coils of small magnets or the

THE Al^OMOBILE HAND-BOOK 195

cores of induction coils are usually wound with
cotton covered wire or in some instances the fine
w're is silk covered, as in the case of secondary
or jump-spark coils.

Intensifier— See Spark Gap, Extra.

Interrupter — See Vibrator Coil.

Joint, Knuckle— See Swivel Joints.

Joint, Universal — See Universal Joints.

Jump-spark Coil — See Electrical Ignition,
also Induction Coil.

Kerosene, Use of, in Motor Cylinders.

Kerosene injected into a motor cylinder and
allowed to remain over night will remove all deposit
from the piston head. It should then be blown
out through the relief -cock or the exhaust- valve.

Kerosene is also used to remove the gummy
residue left on the piston and the cylinder wall
by the lubricating oil. When injected into the
cylinder in the manner above described, it
facilitates the starting of the motor, if it has been
standing idle for any length of time.

Figure 59 shows a form of kerosene cup whicfi
may be permanently attached to the motor. After
removing the cap, the cup is filled and the kero-
sene admitted to the motor cylinder by depressing
the valve-stem.

Kilogram— See Table No. 15.

Kilometet— See Table No. 15.

Knocking, Causes of. Knocking or pounding
is an inevitable warning that something is wrong

196

THE AUTUMOBILli HA.NU-BOOK

with a motor. It may be due to any of the
following causes:

Premature ignition: The sound produced by
premature ignition may be described as a deep,
heavy pound.

Using a poor grade of lubricating oil will
cause premature ignition. The carbon from
the oil will deposit on the head
of the piston in cakes and lumps,
and will not only increase the
compression but will get hot
after running & short time and
will ignite the chai^ too early,
and thereby produce the same
effect as advancing the spark
too much. If this is the cause
the pounding will cease as soon
as the carbon deposit is removed
from the combustion chamber.
Badly worn or broken piston-rings.
Improper valve seating.
A badly worn piston.

Piston striking some projecting point in the
combustion chamber.

A loose wrist-pin in the piston.
A loose journal-box cap or lock-nut.
A broken spoke or web in the flywheel.
Flywheel loose on its shaft.
If the spark plug be placed so as to be ^cactly
m the center of the combustion space, an objectitai-

THE AUTOMOBILE HAND-BOOK

197

Table No. 15.
English and French Units.

Length.

Centimeter.

Meter.

Kilomettr.

Meter

Kilometer. . . .
Inch

100
100,000

2.539
30.479
160,931

1000

.025
.305

1,609.3

.001

1
.000025
.000304

1.609

Foot

Mile

Volume.

CiiWc
Centimeter.

Liter.

Cubic Meter.

Cubic Inch. . . .
Fluid Ounce. .

Gallon

Cubic Foot . . .
Cubic Yard. . .

16.386
29.572
3785 . 21
28315.3
764,505

.0163
.0295
3.785
28.315
764 . 505

.0037
.0283
.7641

Weight.

Gram.

Kilogram.

Metric Ton.

Grain

Troy Ounce . .
Pound Avs. . .
Ton

.064

31.103

453 . 593

.091

1,000,000

.0311
.4535
907.0
1000

.00045
1.01605
1

Metric Ton. . .

198 THE AUTOMOBILE HAND-BOOK

able knock occurs, which has never been fully
explained. In some motors it renders a particular
position of the spark control lever unusable; tliis'
form of knock disappears either on making a
slight advance or retardation of the ignition.

Explosions occurring during the exhaust or
admission stroke. This is almost always due to
a previous misfire, and it is prevented by stopping
the misfires.

If the ignition is so timed that the gases reach
their full explosion pressure during the com-
pression stroke, that is, if the spark be unduly
advanced when the motor is not running at a
high speed, an ugly knock occurs, and great
pressure is developed on the crank-pin bearing,
wrist-pin, and connecting rod. The result may
be the bending or distorting of the connect-
ing rod.

The crank -pin may not be at right angles to
the connecting rod. Tliis cause of knock is often
hard to find.

The chain may perhaps be loose. This pro-
duces a blow if the chain should jump one of the
sprocket teeth. The noise is not usually called a
knock because it does not recur at uniform
intervals. It is dangerous to run with a loose
chain, as breakage might precipitate a car down
a hill backwards.

The bearings at either end of the connecting rod
may be loose. A knock during the explosion

THE AUTOMOBILE HAND-BOOK 199

stroke, and also at each reversal of the direction
of the piston.

If the crank shaft is not perfectly at right angles
to the connecting rod, the crank shaft and fly-
wheel will travel sideways so as to strike the
crank shaft bearings on one side or the other.

Knuckle-joint — See Swivel -joints.

Lamps — See Gas Lamps.

Leaky Jackets — See Water Jackets.

Leaky Joints. Leaky joints in gasoline or
water pipes may be made tight by means of
coarse linen or canvas, covered with a paste of
litharge and glycerine. This should be again
covered with a bandage of adhesive or sticky
tape, such as is used for electrical purposes.

Leakage of Water or Gasoline. This is

usually due to carelessness, and indicates a
slovenly operator. The loss of water, if small,
may be left till the run is completed. A leakage
of gasoline is far too dangerous to leave alone
under any circumstances. A common cause is a
minute hole in the float of the carbureter,
causing it to flood. The hole can be found by
putting the float into boiling water and watching
for bubbles.

Learning to Operate a Car. Learn to dis-
tinguish normal sound of the motor and its valves,
from the following:

Knocking which may be due to a worn or loose
bearing.

200 THE AUTOMOBILE HAND-BOOK

The absence of explosion in one of the cylinders.

A hissing noise due to leakage of the com-
pression.

A sharp spitting due to leakage during the
explosion stroke.

Any pounding of the admission-valve on its seat.

Any racing of the motor.

The sound of an unoiled or dry bearing.

The rattle of a part becoming loose.

tf=^

■^ 4^

LOCKING DEVICES

Fia60

Owing to the value of the indications from the
above, it is important that no oil-cans, spanners,
or other tools, should be left loose in the car.

A little practice will enable the operator to
distinguish the beat of the motor and the vibration
due to the springs, from the jumping, due to road
surface, so as to note at once:

A broken gear tooth.

A loose chain.

A deflated or punctured tire.

THE AUTOMOBILE HAND-BOOK

201

A broken spring.

IneflFectual explosions due to poor compression.
Backlash in steering gear.
Liter — ^See English and French Units, Table
No. 15.

Locking Devices, for Bolts and Nuts. All

bolts and nuts upon a motor car which are not
provided with locking devices should be inspected
at frequent intervals and tightened if necessary.
The vibration and jars to which a motor car is

subject have an astonishing way of loosening
bolts and nuts. Figures 60 and 61 illustrate six
different methods of preventing bolts and nuts
from becoming loose, by means of

A — A lock-nut, which should be a size smaller
than the nut proper, as shown in the drawing.

B — A headless set screw, tapped into the part
which receives the bolt.

C — A spring washer under the nut.

D — A split pin through both bolt and nut.

202 THE AUTOMOBILE HAND-BOOK

E — ^A split pin through the bolt only, but
fitting in half-round grooves in the nut.

F — A nut-lock with holding down screw.

Loose Connections. These occur in the most
peculiar places. Sometimes a platinum tip gets
free from its carrying screw, sometimes a lead lug
breaks inside a storage battery cell. Sometimes
a disconnection occurs by breakage of a copper
wire inside its unbroken cover — see also Battery
Troubles and Ignition Troubles.

Loss of Power — See Misfiring and Over-
heating.

Low-tension Current — See Electrical Ignition,
also Ignition Devices.

Lubricants, Use of. To ensure easy running
and reduce the element of friction to a minimum
it is absolutely necessary that all such parts should
be supplied with oil or lubricating grease, but it
is also a fact, not so well understood, that
different kinds of lubricant are necessary to
the different parts or mechanisms of a motor
car.

As the cylinder of an explosive motor operates
under a far higher temperature than is possible
in a steam engine, consequently the oil intended
for use in the motor cylinders must be of such
quality that the point at which it will bum or
carbonize from heat is as high as possible.

While a number of animal and vegetable oils
have a flashing point, and yield a fire test

THE AUTOMOBILE HAND-BOOK 203

suflSciently high to come within he above require-
ments, they all contain acids or other substances
which have a harmful effect on the metal surfaces
it is intended to lubricate.

The general qualities essential in a lubricating
oil for use in motor cylinders include a flashing
point of not less than 360 degrees Fahrenheit, and
fire test of at least 420 degrees, together with a
specific gravity of 25.8.

At 350 to 400 degrees Fahrenheit, lubricating
oils are as fluid as kerosene, therefore the adjust-
ment of the feed should be made when the lubri-
cator and its contents are at their normal heat,
which depends on its location in the car. Steam
engine oils are unsuitable for the dry heat of
motor cylinders in which they are decomposed
whilst the tar is deposited.

All oils will carbonize at 500 to 600 degrees
Fahrenheit, but graphite is not affected by over
2,000 degrees Fahrenheit, which is the approxi-
mate temperature of the burning gases in an
explosive motor. The cylinder of these motors
may attain an average temperature of 300 to 400
degrees Fahrenheit. So that graphite would be
very useful if it could be introduced into the
motor cylinder without danger of clogging the
valves and could be fed uniformly. These diffi-
culties have not yet been overcome. Graphite is
chiefly useful for plain-bearings and chains.

The film of oil between a shaft and its bearing

204 THE AUTOMOBILE HAND-BOOK

is under a pressure corresponding to the load on
the bearing, and is drawn in against that pressure
by the shaft. It might not be thought possible
that the velocity of the shaft and the adhesion
of the oil to the shaft could produce a sufficient
pressure to support a heavy load, but the fact
may be verified by drilling a hole in the bearing
and attaching a pressure gauge.

Roller and ball-bearings provide spaces, in
which, if the oil used contains any element of an
oxidizing or gumming nature, a deposit or an
adhesive film forms upon the sides of the chamber,
the rollers or balls, and the axle. This deposit
will add to the friction, hence it is the more
important to use a good oil or a petroleum jelly
in such bearings.

Air-cooled motors, being hotter than water-
cooled, must liave a different lubricant, or one
capable of withstanding higher temperatures.

The effect upon animal or vegetable oils of
such heat would be to partially decompose the
oils into stearic acids and oleic acid Itnd the con-
version of these, into pitch. Such oils are there-
fore inadmissible for air-cooled motor use.

Mineral oils are not so readily decomposed by
heat, but at their boiling points they are con-
verted into gas, and any oil, the boiling point of
which is in the neighborhood of the working tem-
perature of the motor cylinder, is useless, as its
body is too greatly reduced to leave an effective

THE AUTOMOBILE HAND-BOOK 205

working film of oil between the cylinder and the
motor piston.

The essentials for the proper lubrication of air-
cooled motors are:

That the oil should not decompose.

That it should not volatilize, as this will result
in carbon deposits.

That its viscosity should be equal to that of a
good steam engine oil at similar temperatures.

That it should be fluid enough to permit of its
easy introduction into the cylinder.

That it will have no corrosive effect on the
cylinders and no tendency to gum.

That it will not oxidize with exposure to air
and light.

Lubrication, Splash and Pressure Feed.

Some makes of vertical cylinder motors use the
splash system, whereby oil fed by gravity from a
tank above the level of the crank-case flows into
the crank-case, whence it is splashed over the
piston and the wrist and crank-shaft bearings.
The large end of the connecting rod, which works
in the crank-case, is made to dip or splash into a
bath of oil. This lubricates the crank-pin. The
splashing is invariably utilized to lubricate the
cylinder by wetting the bottom of the piston and
splashing into the cylinder. A little ring is some-
times made in the crank-case, into which the
oil collects and into which also the end of the
piston dips. The oil usually requires changing

206

THE AUTOMOBILE HAND-BOOK

every 100 miles on small motors or every 75 miles
on large.

Figure 62 shows a vertical cylinder motor using
splash lubrication.

With the use of high-speed gasoline motors, it
has been found necessary to use a forced circula-

tion of the oil in order to
completely lubricate the inte-
rior of the cylinder. The usual
method with high-powered mo-
tors is to employ a belt-driven
pump to force the oil through
adjustable conduits to the
various moving parts. Such
pumps, operating in ratio to
the speed of the motor, supply
lubricant more rapidly as the motor speed
increases, and less as it decreases. Thus, a per-
fect supply is maintained, on the one hand, and
flooding of the motor is prevented on the other.
Where horizontal cylinders are used, it is
customary to use grease cups, and to control the
feed by mechanical or spring pressure. Such
devices are less suitable for vertical cylinder
motors, which require oil in large quantities and
exact adjustment in its flow. One very useful
feature of oil pump lubrication is that the flow of
oil may be kept in proportion to the speed of the
motor. This is a very necessary feature, as
without it flooding is liable to result.

THE AUTOMOBILE HAND-BOOK

207

Lubricators. It should be ascertained from
the maker of the car, how many drops of oil per
minute are necessary for the diflferent mechanisms
of the car, including the motor. The lubricators
should then be set accordingly.

It should be remembered that in cold weather
when the oil is thick a diflferent adjustment of the
lubricators will be necessary from that found
suitable in warm weather. It is important that

the lubrication should be regular, and good oil
used, but not too much. Too much oil will foul
the spark plugs, clog the valves, and interfere
with the quality of the explosive mixture. For
this reason the lubricators should always be care-
fully closed when the car is stopped. If a
mechanical lubricator is used, examine the
mechanism sometimes, and do not trust entirely
to the feed. If a pressure lubricator is used, see

THE AUTOMOBILE HAND-BOOK

that the pbton or cap is tight, for if not the [n«s-
Eure will stop the lubricaUoa.

It sometimes happens that an oU pipe or oil
hole is stopped up and neetis cleaning, or perhaps
the plug at the bottom of the crank chamber has
come unscrewed and dropped out, losing all the
oil. The proper amount of oil in the crank-case
is about half a pint. An extra lubricator leading
to the cylinders and crank-case should be fitted.
so that extra oil can be ted by a hand pump, if
there is any doubt about the motor getting
enough.

Figure 03 shows four forms of lubricators for
automobile use.

A — Plain, glass body oil cup, feeds only when
shaft is running.

B — Sight feed, glass body oil cup, has an
index-arm on t(^
which indicates
whether the (ul
feed is (^ or on.
C — Pressure
feed, piston form
of lubricator, for
heavy bodied oil ;
the oil is forced
into the bearings by means of a spring-actuated
piston in the lubricator.

E> — Plain grease cup, oil or grease forced into
the bearing by screwing down the cap.

LUBRICATOR'

THE AUTOMOBILE HANI>-BOOK

A form of pressure lubricator is illustrated in
Figure 64, in wliich a slight pressure from the
crank-case of the motor causes the oil to be
forced through the pipes leading to the diifercnt
parts of the motor. This form of pressure
lubricator is only applicable to opposed-cylinder
motors with enclosed crank-case, as shown in the
drawing, or to vertical two-cylinder motors with
both pistons connected with one common crank-
pin.

Machine Screws, Dimensions of — See Table
No. 16.

Table No. 16.

Dimensions of Machine Screws.

Dlim

t*rotnoad.

1°

III

■si

Sfi

.084

.053

ifi

1.1

.13

:h«

.110

.062

a?.

-22

.20

.17

.136

-082

■:'S

.27

.22

Sii

,163

-109

:i5

III

:cj

.26

^■■^

.189

,135

;«i

,37

,35

.30

.219

.144

,43

.34

.242

■Mi

.268

.182

,53

,49

.43

.294

,198

,58

.52

.47

Manometer. A device for indicating either
the velocity or the pressure of the water in the
cooling system of a gasoline motor.

210

THE AUTOMOBILE HAND-BOOK

Magneto — See Generator.

Materials, Strength and Weight of-

Table No. 17.

Table No. 17.
Strength and Weight of Materials.

-See

Material.

Tensile

StreDgth in

pounds per

square inch.

Resistance to
Ck^mpression.

Weight per
cubic inch.

Weight per
cubic foot.

Aluminum

12,000
18,000
23,000
60,000
63,000
18,000
30,000
50,000
36,000
16,000
18,000
50,000
33,000
100,000
63,000
60,000
63,000
4,600

10,000
12,500
12,000
12,000
30,000
40,000

15,666

100,000

80,000

36,000

40,666

36,000
36,000
40,000

.094
.290
.295
.290
.300
.313
.317
.317
.290
.260
.267
.280
.410
.284
.284
.284
.284
.265
.247

162

504

510

500!

530

542

548

504

450

460

480

711

490

459

438

Brass — Cast

Sheet

Bronze — Aluminum . .

Phosphor . . .
Copper — Cast

Sheet

Wire

Gun Metal

Iron — Cast

Malleable

Wrought

Lead

Steel— Tool

Cr. Cast

Mild

C. Rolled

Tin

Zinc

8,000

Mensuration of Surface and Volume. Area

of rectangle =; length X breadth.

Area of triangle=baseX one-half the perpen-
dicular height.

Diameter of circle = radius X^.
Circumference of circle=diameterX3.1416.*
Area of circle — square of diameter X .7854.*
* See Table No. 0, Areus aud Circumferences of Circles.

THE AUTOMOBILE HAND-BOOK 211

Area of sector of circle = area of circle X number
of degrees in arc -^360.

Area of surface of cylinder .= circumference X
length, plus the area of both ends.

To find diameter of circle, having given area:
Divide the area by .7854, and extract the square
root.

To find the volume of a cylinder: Multiply

' the area of the section in square inches by the

length in inches = the volume in cubic inches.

Cubic inches divided by 1728= volume in cubic

feet of any body.

The surface of a sphere = square of diameter X
3.1416.

Volume of a spheres cube of diameter X .5236.
The side of an inscribed cube = radius of the
sphere X 1.1547.

The area of the base of a pyramid or cone,
whether round, square or triangular, multiplied
by one-third of its heights the volume.
[ A gallon of water (United States Standard)
f weighs Sjj pounds and contains 231 cubic inches.
I A cubic foot of water weighs 62 J pounds, and
f contains 1,728 cubic inches, or 7} gallons.
! Each nominal horsepower of a boiler requires
\ one cubic foot of water per hour.
\ To find the internal area of a pipe, the volume
and velocity of the fluid or gas being given:
multiply the number of cubic feet by 144, and
divide the product by the velocity in feet per

[

212

THE AUTOMOBILE HAND-BOOK

minute. The area being found, it is easy to find
the diameter of pipe necessary.

To find the pressure in pounds per square inch
of a column of water of given height: Multiply
the height of the column in feet by .434. Approxi-
mately, every foot elevation is equal to one-half
pound pressure per square inch.

To find the velocity in feet per minute necessary
to discharge a given volume of fluid or gas in a
given time: Multiply the number of cubic feet
by 144, and divide the product by the internal
area of the pipe in inches.

Metals, Melting Point of— See Table No. 18.

Table No. 18.
Melting Point op Metals.

Metal.

Temperature
In Degrees
Fahrenheit.

MetaL

Temperature
in Degrees
Fahrenheit

Aluminum

Bronze

Copper

Gold

Iron — Cast

Wrought. .

1160°
1690°
1930°
1900°
2000°
3000°

Lead

620^

3230<»

1730**

2400*»

445**

780<»

Platinum

Silver

Steel

Tin

Zinc

Mica, Use of — See Insulating Material.

Misfiring, Causes of. Misfiring means failing
to fire every charge that the motor takes.

One of the most common causes of misfiring is
an improper mixture of gasoline and air. Too

THE AUTOMOBILE HAND-BOOK 213

much air or too much gasoline will cause
misfiring.

Batteries which are almost exhausted will give
rise to explosions in the motor cylinder which
seem all the more violent on account of their
irregularity. This should be the time to switch
on an extra set of batteries, if one is carried. It
is perfectly useless to connect a set of exhausted
cells with a new set, either in series or parallel,
as it will reduce the new cells nearly to the voltage
of the exhausted ones.

Closing the points of the spark plug will help
the batteries somewhat and may enable the
operator to get the car home.

Examine the battery and all its connections at
the terminals, and determine whether the battery
is exhausted or not, whether there are broken
connections, whether the terminals or other points
need cleaning or attention otherwise. Also
ascertain whether the fuel is bein<j fed to the
motor in proper quantities. It may not be getting
enough at each charge or perhaps too much.

Short-circuits and current leakage by contact of
a bare place on a wire with some metal portion
of the car, or by a spark plug with defective
insulation will also cause the motor to misfire.
The spark may arc or jump elsewhere than
between the platinum points of the plug, render-
ing a new plug or fresh insulation necessary.

A loose connection in the primary or secondary

214 THE AUTOMOBILE HAND-BOOK

circuit Ls another source of misfiring. A loose
wire may be in contact and allow one or two
explosions to take place. The vibration of the
car afterwards may shake the wire loose from its
contact and then the motor will misfire. All
connections should be carefully cleaned and
scR»wcd tight.

If the spark plug is covered with soot or grease
misfiring will often result. A spark gap device
placed in the secondary circuit will generally over-
come this difficulty, but prevention is better than
cure and over-lubrication should be avoided and
the best grade of cylinder oil used. ^

Mixing Valves— See Carbureters.

Motor, Electric — See Electric Motors.

Motor, Pour-cycle — See Explosive Motors,
also iMuir-cvcle Motor.

Motor, Gasoline —See Explosive Motors, also
Gasoline Motor Constniction.

Motors, Speed Regulation of Gasoline. To

secure the greatest efficiency and power of the
motor it is neccssarv' to be able to control its
s])ce(l, and there are various ways to accomplish
tills object. The ran<]je of speed of different
motors varies considerably. With small single-
cylinder motors it is necessary that the speed
should be vcrv threat in order to secure sufficient
power, while with two and four-cylinder motors
this is not necessary, and consequently they are
more durable. As a rule the speed varies from

THE AUTOMOBILE HAND-BOOK 215

about 750 revolutions per minute for the latter
to 1,500 for small motors.

There are various methods of governing, which
are enumerated and described herewith.

Advancing or retarding the ignition.

Exhaust-valve lifter.

Exhaust-valve regulator.

Regulating the lift of the admission-valve.

Mechanically governing the exhaust-valve.

Advancing or retarding the ignition. This is
the method adopted for single and double-cylinder
motors, and consists in changing the time at
which the spark occurs in the combustion chamber
by means of a small lever. If the full force of
the explosion occurs in the combustion chamber
at the moment when the piston is at the end of
its stroke, its effect will be greatest. The
duration of pressure on the piston can be reduced
by altering the timing of the spark, so that it
occurs after the piston has passed the end of the
stroke. This is the simplest method, but its
proper use depends largely on the skill and
experience of the operator. When this method is
adopted, a throttle is also used, which enables
the operator to regulate the quantity of mixture,
and alter the power of the explosion. When the
maximum power is required, the throttle is wide
open, and the spark advanced to the utmost.

Exhaust-valve lifter. This operates by pre-
venting the exhaust-valve from closing after the

216 THE AUTOMOBILE HAND-BOOK

exhaust gases have escaped. When the exhaust-
valve is held up, no explosive charge is taken into
the cylinder.

Exhaust- valve regulator. This method consists
in regulating the lift of the exhaust-valve, but
docs not prevent the valve from closing in the
usual manner. It is also used in connection with
the spark advance. When the maximum power
is required, the exhaust-valve is not interfered
with, and opens to its fullest. When less power
is required, the exhaust- valve is prevented from
opening as much. Consequently the exhaust
gases are not fully expelled, and as they partially
fill the space in the combustion chamber, a full
charge of mixture cannot be admitted through
the admission-valve, and the force of the explosion
is weakened.

By regulating the lift of the admission-valve.
By increasing the strength of the valve spring,
the ad mission- valve is prevented from opening to
its fullest extent, and a full charge is not admitted
to the combustion chamber.

By mechanically governing the exhaust-valve.
This is effected by preventing the cam from lift-
ing the exhaust-valve after an explosion has taken
place. This system is adopted on two and four-
cylinder motors, and is the one most generally
used on cars of European make.

Motor, Two-cycle. Figure G5 shows a
vertical cross-section of a two-cycle type of motor :

THE AUTOMOBILE HAND-BOOK

217

that is to say, it shows the motor as it would
appear if cut in two directly through the center.
This type of
motor is partic-
ularly adapted
to marine pur-

Fio. 65 1

%A..<

W .

J 1

-L

B !

D /

5 r 1

^^^^jrj

TWO-CYCLE MOTOR

poses on ac-
count of its
simplicity, ab-
sence of gearing
and the slight
knowledge re-
quired on the
part of the oper-
ator to handle
it successfully.
This form of
motor, how-
ever, has not
been found the
most satisfactory for automobile use. Its cycle of
operation is fully described under Explosive Motors.
C is the crank chamber. It has two feet, or
lugs, D as shown in the drawing, for the purpose
of attaching it to its position in a boat or else-
where. There is an opening at A for the recep-
tion of the mixing-valve. The flywheel F, crank
shaft G, connecting rod H, piston P, inlet-port B,
baffle-plate J and exhaust-opening E, are plainly
shown in the drawing.

218 THE AUTOMOBILE HAND-BOOK

To the top of the piston P is attached a cone-
pointed projection K. This is on the right-hand
side and is placed there to break the electrical
circuit between the contact-points of the igniter.
This is effected by the cone-point K striking the
right-hand end of the lover L, which causes the
lever to rise at that end and fall at the other,
thus breaking the contact between it and the
insulated igniter terminal M. This breakage of
the circuit causes a spark to occur between the
left-hand end of the lever L and the point with
which it was, a moment before, in contact. This
action takes place once in each revolution of the
motor and just before the piston reaches the end
of its upward stroke.

The ignition may be retarded or advanced by
raising or lowering the fulcrum of the lever L, by
means of the eccentric shown.

The upper part of the cylinder is incased by a
water jacket W, as is the cylinder head or
cover N.

While it may seem possible that the two-cycle
motor should be capable of a higher degree of
power, as well as a greater speed than a four-
cycle motor, the reverse is true in its practical
performance. It is a very satisfactory type of
motor for low or medium speeds, and under such
conditions it is claimed that it will develop at
least 30 per cent more power than a four-cyde
motor. At high speeds, such as are needed in

THE AUTOMOBILE HAND-BOOK 219

explosive motors for automobile use, the objection
to the two-cycle motor is that, all the functions of
admission, compression, explosion and exhaust
being in a single revolution of the motor,
sufficient time is not allowed for the expulsion
of the burned gases, with the result that the
cylinder chokes itself up, and the quality of
the mixture consequently falls below the explod-
able point.

While a four-cycle motor of a given power will
run as high as 1,000 to 1,200 revolutions per
minute, a two-cycle motor of the same dimensions
will not nm over 750 to 900 revolutions. It is
on this account that the two-cycle motor has so
far not proved as successful as might have been
expected for automobile use.

Motor Troubles — See Battery, Carbureter and
Ignition Troubles, also Misfiring and Overheating.

Mud-guards. On many cars the mud-guards
are a constant source of trouble, due to improper
methods of attaching them to the frame or body
of the car. The attaching bolts should be of
large size and the irons to which the mud-guards
are fastened should be much larger than the
mere weight of the guards warrant. The guards
should be strong enough to withstand any or all
of the following conditions :

A heavy wind pressure., especially a head or
partial side wind.

Motor vibrations and road jars.

220 THE AUTOMOBILE HAND-BOOK

The weight of some idiot who insists on leaning
on them when the car is standing.

Mufl3er. The exhaust-pipe from the motor
which conducts oflF the gases after they have done
their work in the cylinder is connected to a
chamber, called a muffler, attached to the frame
of the car. The object of the muflSer is to
deaden the noise of the escaping gases by:

Breaking up the gases into a number of fine
streams.

Allowing the gases to expand and cool.

Checking the velocity without putting t<x> much
back pressure on the motor.

Reducing the pressure of the gases till they are
as nearly as possible at atmospheric pressure.

To do this, the chamber is divided up into
two or more compartments, and the gases in
their passage from one to the other have to
pass through baffle-plates or tubes, drilled
with a number of fine holes, the combined
area of which must be considerably in excess
of the area of the exhaust-pipe, to allow of
a free passage for the expanding gases. The
flow is thus broken up and subdivided into a
number of fine streams of cool gas at or near
atmospheric pressure, which cause little or no
noise on their escape into the air. It is the
sudden expansion of the gases at a high pressure
which causes the noise at the exhaust-opening
of the motor.

THE AUTOMOBILE HAND-BOOK

221

Figure 66 illustrates a form of muffler with a
central inlet-pipe, provided with slotted openings
as shown. The
chamber is di-
vided into two
parts by a plate,
in and around
which are lo-
cated a number
of small tubes
for the passage
of the gases. A similar set of tubes are located
in the discharge end of the muffler.

Muffler Gut-out. A cut-out is a very desir-
able addition to a good muffler, not only for the
extra power gained by its use, but when adjusting
the motor it is sometimes necessary to listen to the
sound of the exhaust to ascertain if the motor is
working properly.

Needle-valve — See Valves.

Negative Pole— See Current, Direction of,
also Polarity.

Nuts, Locking Devices for — See Locking

Devices.

Oil — See Lubricants.

Oil Pump— See Oilers, Ratchet-feed and
Rotary.

Oilers — See Lubricators.

Oilers, Ratchet-feed and Rotary. Mechanical
or power-operated lubricators are of two kinds;

222 THE AUTOMOBILE HAND-BOOK

The first has the piston or plunger cams operated
by means of a pawl and ratchet-wheel, tlirough
a connecting rod attached to some reciprocating
part of the motor, or to a crank on the end of
the cam shaft. The second form has its pump
shaft driven by a belt, chain or gear from the
motor. The ratchet-feed oilers are not suitable
for motor speeds over 600 revolutions per minute,
while the rotary oiler may be used with miotors of
any speed by the use of a simple form of reducing
gear.

Overcharging — See Storage Batteries.

Overheating, Causes of. The immediate

effect of overheating is to bum up the oil in the
cylinders or crank case. This causes a smell of
burning and an odor of hot metal. There is
sometimes a slight smoke and the motor will
make a knocking sound. The cooling water
begins to steam, and the car will gradually slow
down and finally stop.

The most serious cause of a stoppage on the
road is overheating, which causes the lubricating
oil to burn up and the piston to expand and grip
or seize in the cylinder.

Insufficient lubrication increases the friction
between the piston and cylinder, and so generates
extra heat. Bad or unsuitable oil may have the
same effect.

Too much mixture or too rich a mixture also
causes increased heat.

THE AUTOMOBILE HAND-BOOK 223

Any failure in the water circulation, unless
detected at once, will cause overheating, the
results of which may prove very serious. For
this reason a careful watch should be kept on the
manometer. If this useful device is not fitted, the
motor and pipes should be felt by the hand.

As soon as any of the above symptoms are
noticed :

The motor should be stopped at once.

Kerosene should be copiously injected into the
cylinders and the motor turned by hand to free
the piston-rings.

The parts should then be allowed to cool.

Do not pour cold water on the cylinder jackets,
for fear of cracking them, but pour the water
into the tank so as to warm the water before it
reaches the cylinder jackets.

A simple test in the case of an overheated
motor is to let a few drops of water fall on the
head of the cylinder. If it sizzles for a few
moments the overheating is not bad, but if the
water at once turns into steam, the case is
serious.

Detach the spark plug or plugs, and turn
the starting-crank slowly. This draws in cold air
and cools the inside of the cylinder and the piston.

Packing. Packing or material for making gas
or water-tight joints is of various kinds. Asbes-
tos packing comes in sheets, called asbestos paper
or board, in the form of woven cloth, and also as

224 THE AUTOMOBILE HAND-^OOK

string or rope. Rubber packing is made in

slieets, either plain or with alternate layers of

canvas and rubber. Some forms of packing are

known as Rubberbestos and Vulcabestos and are

made of asbestos, impregnated with rubber and

afterwards vulcanized.

Parts, Extra. The necessity for carrying extra

parts upon a car becomes more apparent when a

breakdown occurs miles away from home, and no

material at hand to repair the break with. The

accompanying list gives some of the parts generally

needed in time of trouble:

Bolts and nuts. Inner tube. Split pins.

Chain links. Insulated wire. Sticky tape.

Dry batteries. Packing. Valve springs.

Extra valves. Spark plugs. Washers.

Picric Acid. Gasoline will absorb or take up
about 5 per cent of its weight of picric acid.
The addition of a small quantity of kerosene will
enable the gasoline to absorb about 10 per cent
of picric acid.

Picric acid is only dangerous when fused, or
when in a highly compressed state.

An increase in motor efficiency of about 20 per
cent is claimed for the picric-gasoline mixture.

About three-tenths of a pound of picric acid is
required for each gallon of gasoline. The mixture
should be allowed to stand for two days, agitating
occasionally during this time, then strain through
two or three thicknesses of very fine muslin before
using.

THE AUTOMOBILE HAND-BOOK

225

The explosive force of picric acid is very much
overrated. If thrown upon a red hot plate of
iron, it simply bums with a smoky flame, and
striking a small quantity of it upon an iron anvil
will not explode it.

Pipe Nipples. Nipples are always ordered by
the nominal diameter of the pipe and the over-all
length of the nipple. Table No. 19 gives the
standard lengths of nipples of varying diameters,
also the number of threads per inch and the out-
side diameter of the pipe.

Table No. 19.

Length of Standard Pipe Nipples.

Nominal
Diameter.

Outside
Diameter
of Pipe.

Threads
per Inch.

Over-all Length of Nipples.

Close.

}

Short.

Long.

.40

.54

.68

.84

1.05

1.32

1.66

1.90

2.38

226 THE AUTOMOBILE HAND-BOOK

Pipe, Wrought Iron— See Tabic No. 19.

Pistons. The piston used in a gjusoline motor
cylinder is of the single-acting or trunk type. It
is made of an iron casting wliich is a good work-
ing fit in the cylinder. Around the upper end of
the piston three or four grooves are cut, and in
these grooves the piston-rings fit. The rings are
made of cast iron, and the bore of the ring bein^
eccentric to its outer diameter, there Ls a certain
amount of spring in them, and so pressure is
caused against the cylinder wall, preventing any
of the expanding gases passing the piston.

'^riie lubrication of the piston-rings is verj'
important, for on that depends the proper work-
in«( of the piston in the cylinder. In single-
cylinder motors, the piston-rings require frequent
attention, and kerosene should be injected into
the spark plug opening at frequent intervals.
Oeeasionallv the cylinder should be token off,
and the rings cleaned with a brush and kerosene.
In nmlti-cvlinder motors, this constant attention
is not riHjuired, for in addition to the splash
system of lubricaticm, usually, there are pipes
leading to the cylinders, through which oil is fed
and so keeps them well lubricated. The speed
of the motor being so much less, there is no
danger of the oil being usal up rapidly.

Piston Displacement. The piston displace-
ment of a motor is the volume swept out by the
piston, and is ec|ual to the area of the cylinder

THE AUTOMOBILE HAND-BOOK 227

multiplied by the stroke of the piston. The
expression, cylinder volume, is sometimes con-
founded with the term piston displacement. This
is erroneous, as the cylinder volume is equal to
the piston displacement, plus the combustion
space in the cylinder head.

Pistons, Length of. For vertical cylinder
motors the length of the piston should not on any
account be less than its diameter, while a length
equal to one and one-quarter or even one and
one-third diameters is better. For motors with
horizontal cylinders the length of the piston, in
any case, should not be less than one and one-
third diameters, and if possible one and one-half
diameters or over.

Piston-rings. To ensure proper cf):npressir>n,
it is absolutely essential that the [)istc)ri-rings
should be kept lubricated; consecjuently when the
motor has been idle for some time, the com-
pression at the start is often poor. Any failun;
in the lubrication while running will, of four^e,
have the same eflfect, such, for example, as in the
case of overheating, or when the su[)ply is inter-
mittent. Sometimes the piston-rings get stuf-k in
their grooves with burnt oil, through overheating,
and the compression escapes past tlnTn.
Thorough cleaning with kerosene and fresh lubri-
cating oil will settle the matter. In motors wh<»re
the rings are not pinned in positicm, the slots may
work round so as to coincide, in this caM; they

228 THE AUTOMOBILE HAND-BOOK

will have to be moved around. Sometimes burnt
oil may, apparently, have the opposite effect on
piston-rings, for by causing the piston to grip in
the cylinder, it will produce considerable resist-
ance, and the operator might erroneously think in
consequence that his compression is good. In
every case, after a long run, a little kerosene
should be injected into the cylinders to clean the
rings.

Piston-rings, Method of Tnniiiifr. a

pattern should be made from which to cast a
blank cylinder or sleeve with two projecting
slotted lugs on one end to bolt same to face plate
of lathe. This blank should first be turned off
outside to the required diameter, making it, of
course, sufficiently larger to allow for the cut in
the rings, after cutting from the blank. The
blank should then be set over eccentric sufficiently
to allow the thick side of the rings to be twice the
thickness of the thin side after turning. The
inside of the blank can then be bored out, and
the rings cut off to the exact thickness required
with a good sharp cutting off tool. A mandril or
arbor should be made with two cast iron washers
or collars to fit on it, one fastened to the mandril
and the other loose, with lock nut on mandril
with whicli to tighten up the loose collar. After
the rings have been sawed open and a piece cut out
the recjuired length, they can be placed in a coUar
or ring about 1-32 to 8-G4 of an inch laiger than

THE AUTOMOBILE HAND-BOOK 229

the cylinder bore, and slipped on to the mandril
one at a time of course, with the loose collar and
nut oflf the same. The loose collar and nut can
then be put on the mandril, the ring clamped
tightly between the two collars, the mandril put
in the lathe and the ring turned oflf, without leav-
ing any fins or having to cut the ring oflF after-
ward as is done in many cases. This is the
only way in which a perfectly true ring can be
made.

Piston Velocity, Limitation of. The speed

of rotation of an explosive motor is limited by the
fact that the velocity of the piston must be con-
siderably less than the rate of combustion of the
explosive mixture, in order that the motor may
develop energy or do work. The practical limit
of piston velocity is said to be between 14 and 16
feet per second.

Plain-bearing Axles — See Axles.
Plain-bearing Hubs— See Hubs.

Platinum. The contact points of the vibrator
of an induction coil should always be of platinum.
German silver or any other metal spoils the
quickness of the break on account of the greater
tendency of the contact-points to carbonize, when
of any other metal than platinum. Spark plug
points should also be of platinum or iridio-plat-
inum, which is better yet, as it is more capable
of withstanding the intense heat in the combus-
tion chamber than the platinum itself. Any

230 THE AUTOMOHILE HAND-BOOK

other metal than platinum (except gold) will turn
green or black if tested with nitric acid.

Points to Learn. If a motor does not ignite
its first charge there is a cause for it, and no
amount of turning of the crank will locate it. A
little common sense will not only locate but
remove the cause, and the motor will do its own
turning after the first two or four revolutions.

See that every charge the motor takes in is
exploded, for which a proper mixture and a good
spark are necessary.

Never throttle the mixture so closely that the
motor cannot get a full charge every time it needs
it.

Always use the very best cylinder oil in the
cylinder, and a good quality of lubricating oil in
the crank case.

Learn how to properly adjust the vibrator of
the coil.

Learn how to set the valve gear correctly.

I^eam how to locate and remedy loss of com-
pression in the motor.

Learn how to fix a bearing or piston which has
seized.

Always throw the clutch, throttle or spark-
advance levers in gradually.

Buy a densimeter, and learn how to test the
quality of the gasoline.

Learn how to grind in the valves, also how to
fit new piston-rings.

THE AUTOMOBILE HAND-BOOK 231

Never leave the car with the motor running.
A slight touch of the clutch-lever may cause the
car to run away.

See that the water-cooling system has a drain-
cock so that the water can be drained in the
winter.

Once a month wash out the pipes, water jacket
and water tank with a strong solution of
common soda or lye. Let the motor run a few
minutes before emptying the solution, then
empty the tank and pipes and repeat the opera-
tion with clean water. This process will tend to
insure uniformly effective circulation of the water.

Never pour gasoline near a naked flame. It is
safer to extinguish all except electric lights, when
filling the gasoline tank of a car.

Always remember that gasoline is a highly
volatile and inflammable liquid and its vapor is
far more inflammable when mixed with air.

If the motor works well, leave it alone, although
it may never seem speedy enough.

Points to Remember. That if a motor

nearly stops and then goes on again, it is due to
lack of gasoline at the carbureter. There is
probably dust, dirt, or other deposit at the inlet
of the carbureter, which, however, sometimes
frees itself. To avoid these troubles gasoline
should never be poured into the tank except
through a funnel fitted with a fine gauze strainer
or a piece of muslin.

232 THE AUTOMOBILE HAND-BOOK

That an unusual noise or squeak is evidence of
lack of lubrication, and generally foretells a
breakdown unless looked after at once.

That air must always find an inlet to the gaso-
line lank in order that the gasoline may flow out
freely, and considerable trouble has been caused
by the vent-hole in the cap of the gasoline tank
becoming blocked.

That the motor will not run unless the gasoline
is flowing from the tank to the carbureter.

That the motor will not start if the switch-plug
is in your pocket.

That the motor will not start until the switch
is turned on.

That there must always be good electrical con-
nections between the battery, spark coil and spark
plug.

That too much lubricating oil must not be
used. It causes: the valves to stick, a deposit
on the spark plugs, and a poor combustion in the
cylinder. Excess of lubricating oil reveals itself
in the form of smoke at the exhaust.

When the motor is in proper working order »
and turned with the crank, a considerable resist-
ance should be felt at every alternate back stroke
of the piston. This back pressure should require
a considerable effort to overcome when the crank
is turned slowly. If the compression of any
cylinder is poor, that cylinder will not give it9
full power,

THE AUTOMOBILE HAND-BOOK 233

Finally, remember that if your motor is misfir-
ing or not running properly, the trouble may of
its own accord disappear after a little running.

Polarity. To ascertain the polarity of the
terminals of a storage battery or light circuit,
place the ends of the wires on the opposite ends
of a small piece of moistened litmus paper. The
wire on the side of the paper which has turned
red is the negative pole of the battery — see also
Current, Direction of.

Porcelain. Porcelain tubes used for the insu-
lation of the center rod of a spark plug, have
higher insulative properties than lava or mica,
but on account of the liability of the porcelain to
break from too sudden change of temperature, it
is not as reliable as other forms of insulating
material.

Positive Pole — See Current, Direction of, also
Polarity.

Power, Loss of — See Misfiring and Over-
heating.

Power Transmission Devices. The power

transmitting devices or mechanisms used on
gasoline motor-cars may be divided into three
classes : The Differential gear which transmits
the power from the speed-change-gear to the
rear-axle or wheels of the car. The Priction-
clutch which forms the connecting and discon-
necting medium between the motor and the speed-
change-gear. The Speed-change-gear which

234 THE AUTOMOBILE HAND-BOOK

transmits the power of the motor to the tlifferentiid
gear at varying speeds, entinly independent of
the motor speed.

DiFFERENTiAi, GfiJAHS. The differential gear of
a motor-car acts in a similar manner to the
whipple-tree of a two-horse wagon, the difference
being tliat the differential gear acts continuously
in a rotary manner, while tlie whipple-tree acts
only through a short horizontal range of move-
ment. It may also be compared with the equal-
izing bars of the locomotive driving whecU.

Two forms of bevel gear differentials are shown
in Figure 67. The one at the left of the drawing

Fig. 67

DIFFERENTIAL GEAR

has a jspur fp'ar drive, and is nmch used on
electric cars with motors <lireetly attached to Hie
rcar-iixlc. The dilTcrcntial at the right of the
dnnviiig has a spj-oeket wheel instead of a gear,
through which tlic gear is driven.

THE AUTOMOBILE HAND-BOOK

Figure 68 illustrates two spur gear differentials.
The left-hand one having an internal tooth spur
gear and fixed sprocket wheel, while the right-

Fig. 68

DIFFERENTIAL GEARS

hand differential lias all external tooth spur gears,
and may be fitted with either a sprocket wheel
or a spur gear form of drive.

Friction- CLUTCHES. Friction-clutches are of
various forms, amongst these may be mentioned
those which are generally used on gasoline motor-
cars; they are: The external band-clutch, the
internal expanding-ring clutch, the disk or end-
plate clutch and the cone-friction form of clutch.

THE AUTOMOBILE HAND-BOOK

Fig. 69

CLUTCH

The female member of the cone-friction clutch
is usually an integral part, or attached to the rim
of the motor flywheel, A form of cone-friction
clutch is shown in Figure 69, in which the female
member is attached
to the rim of the fly-
wheel by bolts. The
driving engagement is
effected by the pres-
sure of a spring lo-
cated around the
extension of the fly-
wheel shaft, and be-
tween the hub of the
flywheel and that of
the male member of
the clutch. Disengagement of the clutdi members
is made by foot pres.sure on a pedal attached to
the bell-crank lever shown to the right in the
drawing.

Speed-ciiaxge-geaus. The gears which
effect the change of speed of motor-cars, inde-
{x'ndently of that of the motor, are of many
varieties, among which may be mentioned the
following: Planelary-gears, Internal -gears, In-
ternal-clutch gears, Sliding^ears and Positive-
clutch gears.

A planetary or epicj-clic form of speed-change-
gear is illustrated in Figure 70, which has two
speeds forward and a reverse. The fast speed is

THE AUTOMOBILE HAND-BOOK 237

obtained by means of the disk or plate-friction
clutch shown at the left in the drawing, which
locks the parts of the gear together so that it

Fig. 70

PLANETARY GEAR

revolves with the motor shaft as a single unit.
When on the slow speed the reverse gears are in
action, but at a slower rate of speed than the
forward motion of the device.

Figure 71 shows a form of internal planetary
speed-change-gear, also having two speeds for-
ward and a reverse. The fast speed is obtained
in the same manner as the gear described in
Figure 70, When the gear is running on the slow
forward speed, the internal gear of the reverse is
running backwards at nearly the same rate of

238 THE AUTOMOBILE HAND-BOOK

speed as the slow forward gear, a Teature which
lias many objections.

A speed-change-gear having internal or indi-
vidual clutches in each change-gear, Ls shown in

Fro. 71

L_ i

INTERNAL GEAR

Figim' 73. These clutches are operated one at a
thne by means of the cones on the ends of the
grooved collars, engaging with the d<^ attached

THE AUTOMOBILE HAND-BOOK 23ft

tothe male members of theclutches. Thereverse
is obtained by means of an idler pinion shown

Fig. 72

'— ' CLUTCH GEAR

between the two gears at the right in the draw-
ing. Figures 73 and 74 show two forms of
speed -change-gears with spur teeth which slide in
and out of mesh with each other, hence the term,
sliding-gear. The gear shown in Figure 73 lias
a device by which the cone- friction -clutch is
thrown out of gear, before the various pairs or
sets of gears are engaged or disengaged with each
other. Both speed- change-gears have three
speeds forward and a reverse.
Prony Brake— See Brake Tests.

240 THK AUTOMOBILE HAND-BOOK

Pumps, Water CirctUating. If steam is seen
coming from the relief or outlet of the water
circulating system, look for a blockage of the
circulation or failure of the pump.

If some of the radiator tubes are cool and
others are hot, look to the pump.

Fig. 73

SLIDING GEAR

To test the pump before starting, run the
motor for a few minutes. Then ascertain how
long it takes before the top radiator tubes are
thoroughly hot. If the heat of the pipes is
uniform the circulation is all right.

The circulating pump is used in the belief that
it affords a means for regulating the temperature

THE AUTOMOBILE HAND-BOOK 241

of the jacket water supply, which would not
always be the case with a thermal -syphon system.
Such is not the case, as the pump, being driven
direct from the motor, operates at a speed which
varies with the motor speed. On starting the

""'^-^^ li\^ ^

"■^^^flplt-ftjfi—

It^

\^^S¥ft

SLIDING GEAR

-ir

motor, it pumps cold water into the jacket. It
pumps slowly at slow speeds, although the motor
may be taking a full charge and heating rapidly.
It pumps fast at high speeds, although the wind
pressure and its consequent cooling effect may be
very great. If a circulating pump could be used
in connection with a device to control the regu-
lation of the motor temperature, the results would
be more satisfactory.

Rotary pumps used in the water circulating
system of gasoline automobile motors are of two
forms, centrifugal and positive or forced-feed.

242

THE AUTOMOBILE HAND-BOOK

Fig. 75

PUMP

A positive or forced-feed rotary pump is shown in
Figure 75. An annular ring around the pump
shaft carries two blades, one of which is hinged
to, and the other attached directly to the pump

shaft. The
outer ends of
the blades are
supported in
the peripheiy
of the annular
ring and rotate
eccentrically
with it. The
pump shaft is
concentric with
the pump
chamber, but the annular ring is located eccen-
trically around the shaft, which drives it by
means of the fixed blade on the shaft.

Figure 76 illustrates another form of positive-
feed rotary pump, in which the pump shaft is
eccentrically located in the pump chamber. A
short cylinder which forms a part or portion of
the pump shaft, carries two blades in a slotted
opening parallel to and coincident with the axis
of the pump shaft. These blades are kept in
contact with the interior periphery of the pump
chamber by means of coil springs, located
between the blades as shown. Rotation of the
cylinder in the pump chamber causes a sliding or

THE AUTOMOBILE HAND-BOOK

243

reciprocating action of the blades, due to the pres-
sure of the coil springs between their inner ends.

Radiator, Combination Water Tank and — See

Radiators, Water-cooling.

Radiators, Water-cooling. The design of a

radiator should be such that the maximum of
surface is ex-
posed to the
air and the
greatest free-
dom afiForded
for the circu-
lation of the
water. As a
^circle presents
the minimum
surface , it
would appear

that a circular pipe is not the best shape for
a radiator tube. There are, however, many
reasons in favor of the circular section, one of
which is the small resistance offered to the flow
of the water. With a circular shape the minimum
weight of tube is obtained for a given cubic
content of liquid, and the greatest strength also
for a given weight. A flattened tube section is
often used, and is made up to represent in appear-
ance the cellular radiators which have recently
come into use. If the cellular radiators are well
made, they have the advantage of being more

1^44

THE AUTOMOBILE HAND-BOOK

easily cleaned of mud than any other design.
The number of joints forming a honey-comb radia-
tor are likely to be a cause of leakage, and such a
radiator is far more difficult to repair on the road
than the tubular type with radiating fins or disks.

Radiator, Cooling Surface per Horse-
power. Motors using the thermal-syphon or nat-
ural water circulation require about 5 square feet
of radiating or cooling surface per horsepower.

Radiator, Combination Water Tank and.

Four styles of combination water tank and radiator
are shown in Figure 77, having vertical cooling
tubes with radiating disks, honey-comb or cellular

THE AUTOMOBILE HAND-BOOK 245

form of radiation and horizontal tubes, respec-
tively.

Ratchet-feed Otter — See Oilers.
Rear Axles— See Axles.

Regulation, Speed — See Governor, also
Motors, Speed Regulation of Gasoline.

Relation of Spark to Mixture. The relation

of the time of the spark to the mixture is best
learned by experience, but most .always the
highest speed will be obtained when the throttle
is fully open and the spark well advanced. It,
however, happens on bad roads and hills that the
best results are sometimes obtained by retarding
the spark a little, leaving the throttle full open.
With the thi'ottle almost closed and the
spark fully retarded, the motor will just run
itself. Do not open the throttle suddenly, as the
mixture will be more uniform if the throttle is
opened gradually.

Do not advance the ignition until the motor is
up to speed on the throttle. Advancing the
spark suddenly, or before speed is attained with
the throttle will cause pounding. Always advance
the spark after the throttle is full open.

Rheostat. A rheostat is a device for regulat-
ing the flow of current in a closed electrical
circuit, by introducing a series of graduated
resistances into the circuit — see Electric Motors,
Speed Regulation of, also Storage Battery
Charging.

246 THE AUTOMOBILE HAND-BOOK

Road Troubles. Aside from tire troubles and
accidents which may happen to a horse-drawn
vehicle as well as a motor-car, any one of the
following troubles may occur:

Motor misfires badly.

Motor overheats.

Motor almost stops and then starts.

One or more cylinders not firing.

Regular but unusual hissing.

Regular but unusual knocking or pounding.

Regular but unusual puflSng noise.

Motor Misfires Badly. With a single-
cylinder motor this may be due to the fact that
the points of the spark plug are too far apart, or
that oil or soot has got on them. Misfiring in a
multi-cylinder motor is caused from weak or
exhausted batteries, a loose or broken wire in
the ignition circuit, or a poor contact at the
commutator. This applies also to a single-
cylinder motor.

Motor Overheats. A failure in the water
circulaticm from lack of water in the tank or an
obstruction in the pipes is one cause of overheat-
ing. An insufficient supply or shortage of lubri-
cating oil is another. Too rich a mixture or too
iiuicli gasoline for the (juantity of air also causes
overheating, especially by running slow under a
heavy load.

Motor Almost Stops and Tiient Starts.
The gasoline tank intiy be almost empty or the

THE AUTOMOBILE HAND-BOOK 247

cock in the supply pipe partially closed. The
gasoline may be of low grade or stale. There
may be dirt in the gasoline which has partially
clogged the pipe leading to the carbureter. The
union or flanged connection between the car-
bureter and the admLssion-pipe may be loose,
allowing air to enter, thus preventing proper
carburation of the mixture.

One or More Cylinders Not Firing. The
points of the spark plugs may be too far apart;
if not, they may be short-circuited by oil or soot.
If the motor has individual lubrication for each
cylinder, too much oil may be feeding, defiling
the mixture and preventing ignition of the charge.
Stop the working of the vibrators of the coils,
one at a time. In this manner the cylinder
which is not firing may be quickly located.

Regular but Unusual Hissing. This is
due to a leak in the compression. Fill an oil can
with soapy water and apply round the spark plug
opening and the inlet or exhaust- valve chambers.
Air bubbles will indicate the location of the leak.
If the starting-crank be turned quickly the hiss-
ing noise will sometimes locate the leak.

Regular but Unusual Knocking. This
sometimes is an indication that a piston or a
bearing on the motor is about to seize through
overheating. Advancing the ignition too far will
produce the above result. A broken valve-stem,
valve-spring, or a loose or worn wrist or crank-

248 THE AUTOMOBILE HAND-BOOK

pin bearing will also cause a knocking or
pounding.

Regular but Unusual Puffing. K a
puflSng noise is heard which keeps time with the
exhaust of the motor, but does not in any way
affect the running of the motor, the connection
between the motor and the main exhaust-pipe has
worked loose, or there is a crack in the pipe. K
the main exhaust-pipe is all right, one of the
branch exhaust connections to the motor may be
loose. U"

Roller-bearing Axles — See Axles.

Roller-chain — See Chain.

Rotary Oiler — See Oilers.

Rubber, India. All articles made of com-
mercial rubber should be kept from contact with
oil, kerosene, gasoline or grease if they are to be
kept in good condition. Vulcanized rubber
should not be exposed to a temperature of more
than 130 degrees, Fahrenheit. Commercial or
vulcanized rubber contains not to exceed 30 to
35 per cent of pure india rubber, as its stretching
quality, stickiness and rapid deterioration under
the action of light and air make its sole use
undesirable.

Runabout. This term is applied to light
gasoline or electric cars, weighing not to exceed
1,000 pounds, and with a seating capacity for two
persons. Typical American gasoline and electric
runabouts arc illustrated in the Frontispiece.

THE AUTOMOBILE HAND-BOOK 249

Running Gear. A complete running gear
includes the frame, springs, wheels, motor, speed-
change-gear, axles and the machinery of the car
except the body. The French word, chassis, is
sometimes used to designate a running gear, but
its use is not correct, as strictly speaking the
term, chassis, applies to the frame only, or at the
most to the frame and springs.

Figure 78 illustrates a vertical section of a
running gear equipped with a vertical four-
cylinder motor, and longitudinal propeller-shaft
drive, by bevel gearing to the live rear axle.

A plan view of a running gear with double side-
chain drive and rigid rear axle is shown in Figure
79. The motor is also of the vertical four-
cylinder form. The water cooling system in both
cases is by rotary pump, combination tank and
radiator, and fan as shown.

Scratched Cylinder. The cylinder may be
temporarily fixed by taking it to a first-class tin-
smith and having the scratches filled with silver
solder. The soldered places must be then care-
fully scraped flush with the bore of the cylinder.
The best way is to have the cylinder re-bored and
the piston-rings re-turned.

If the scratches are not too deep the cylinder
can be re-bored, and a new set of piston-rings
made to fit the new bore. The limit to such an
increase in bore is about one-sixteenth of an inch.

Screws, Cap — See Cap Screws — Table No. 8.

THE ArTOMOlSII.L: HANlVItfKiK

THE AUTOMOBILE HAND-BOOK 251

Screw-driver, Uses of a. A screw-driver is

one of the handiest and most useful tools on a
car. It can be used to grind in a valve, to press
a valve spring out the way, or to hold a valve
spring up while the spring cap is being put on.
It may also be used as a chisel to tighten a loose
nut, which otherwise cannot be got at.

Secondary Current. The current which takes
its rise in the fine wire of the induction coil, and
which flows through the wire to the spark plug,
is induced in the fine wire by the sudden reversal
of the magnetism of the iron core.

This change of magnetism is caused by the
sudden interruption of the primary current— see
also Electrical Ignition and Induction Coil.

Self-firing, Causes of. If the motor should

continue to run after the switch has been opened,
it is due to an insuflScient supply of lubricating
oil, causing the motor to overheat, or to the pres-
ence of soot or some projection in the combustion
chamber becoming incandescent. It may also be
due to lack of water or to the water circulation
working poorly, causing the motor to overheat.
Self-induction — See Electrical Ignition, also
Induction Coil.

Side-slip of Motor-cars. A wheel with a

weight on it when rotating bites into fresh ground
as it advances. If the wheel rotate more in
proportion than it advances, from any cause, it
thereby loosens the particles of dirt beneath it

252 THE AUTOMOBILE HAND-BOOK

THE AUTOMOBILE HAND-BOOK 253

and loses adhesion with the ground immediately
under the dirt.

The wheel can now slip sideways as easily as
it can slip forwards, particularly when it has the
rounded section slightly flattened, which is the
case with pneumatic tires. When traveling
straight ahead, and with the motor out of gear,
skidding does not usually occur. A slight turn
given to the steering. wheel checks the speed and
introduces a side pressure on both front and rear
wheels, due to the machine tending to continue
its path in a straight line. Generally this side
pressure will not cause skidding. If, however,
the motor be suddenly thrown in gear, or the
brakes suddenly applied, or, what amounts to the
same, a large turn is given the steering wheel, the
wheels find themselves either rotating more than
in proportion to their advance or advancing more
than in proportion to their rotation. Tliis
immediately causes a loss of adhesion, which, once
established, causes the car to skid or side-slip.

Silencer — See Muffler.

Skidding — See Side-slip of Motor-cars.

Solder. Silver solders are generally used for
very fine work. They are very fusible, and non-
corrosive. Hard spelter is used for steel and iron
work, and soft spelter for brass work.

When copper is soldered to iron or zinc, resin
should be used, or if chloride of zinc is used for
a flux, the joint should be washed afterwards to

254 THE AUTOMOBILE HAND-BOOK

remove the acid. Unannealed wires should be
soldered at as low a temperature as possible.
Solder is always an alloy of other metals. It
must not only be more fusible than the metal or
metals to be joined, but it must have some
chemical affinity for them. Different kinds of
solder are therefore employed for different pur-
poses. It is called either hard or soft, aceoiding
to its fusing point.

Solders and Spelters for use with different met-
als, and their proportional parts by weight are

Solder for:

Electrician's use ...1 — Tin, 1 — Lead.

Gold 24— Gold, 2— Silver, 1— Copper.

Platinum 1 — Copper, 3— Silver.

Plumber's— Hard . . 1— Lead, 2— Tin.
Soft ...3— Lead, 1— Tin.

Silver — Hard 1 — Copper, 4 — Silver.

Soft 1— Brass, 2— Silver.

Tin— Hard 2— Tin, 1— Lead.

Soft 1— Tin, 1— Lead.

Spelter for:

Fine brass work. . . .8 — Copper, 8 — Zinc, 1 — Silver.

Common brass 1 — Copper, 1 — Zinc.

Cast iron 4 — Copper, 3 — Zinc.

Steel 3— Copper, 1— Zinc.

Wrought iron 2 — Copper, 1 — Zinc.

Spark Coil — Sec Electrical Ignition, also Induc-
tion Coil.

Spark Gap, Extra. An extra spark gap in
the sccondarv circuit will cause a spark to jump
across the points of a fouled plug because the
intensity of the voltage of the current is reduced
to such an extent that the current will jump
across the points in preference to the path of

THE AUTOMOBILE HAND-BOOK 255

higher resistance formed by the carbon deposit
upon the insulation of the spark plug. As the
spark plug and the spark gap are in series with
each other, it follows that with a single gap — the
spark plug alone — ^the tension of the secondary
circuit is about 30,000 volts, while with two gaps
the tension at each gap will be only about 15,000
volts. That this statement is true may be shown
by an arc light circuit of 500 volts, with five 100-
volt lamps in series with each other in the circuit,
and which have a potential of 100 volts each, and
not 500 volts, as might be supposed. This
explanation, therefore, destroys the claim that the
use of the extra gap intensifies the arc or spark
at the points of the plug. The real advantage of
the extra gap is that the reduction of the voltage,
instead of its increase, reduces the tendency of
the current to arc across the carbon deposit.

The extra spark gap will only be found effec-
tive so long as the carbon deposit upon the
insulation of the spark plug is small, or mixed
with oil, which increases the resistance of this
path. The arcing will continue at the point of
the plug until the carbon deposit is rich enough
to form a path for the entire volume of the
current, when the plug will cease sparking — but
the extra spark gap will continue to arc. One
advantage of the extra spark gap is that it provides
a means of seeing whether the secondary circuit
is in working order without removing the plug

266 THE AUTOMOBILE HAND-BOOK

from the cylinder, and the device should be <
nected in the circuit by a two-point switcl
enable it to be thrown in and out of the secom
circuit. The use of the extra spark gap
never absolutely remove the necessity for kee]
the insulation of the spark plug in good condi
and free from soot or oil. As long as
batteries are strong enough to maintain the
voltage of the primary circuit, just so long
the extra spark gap work successfully in
secondary circuit, and when the electromo
force of the batteries falls below the nor
point, it will be found necessary to cut out
extra spark gap, to maintain an eflScient spar]
the combustion chamber of the motor.

Spark Intensifier — ^See Spark Gap, Extra
Spark Plugs. The trouble with motors i
firing, is generally due to dirty spark plugs. T
is caused by using too much cylinder oil, whi
when subjected to the intense heat in
cylinder, turns to carbon. Tliis carbon depo
on the insulated porcelain and the body of
plug, and instead of the current jumping fi
the point in the body to the point in the porcel
and making a spark, it follows the easiest pj
which is the carbon, and does not make a sp
at the plug points at cill. When this occurs
motor will misfire. The first thing to do w
a motor misfires is to test the spark plug. T
the motor until the battery circuit is clos

THE AUTOMOBILE HAND-BOOK

257

Unscrew the spark plug from the motor, tlien
re-connect the wire to it just the same as it was
before. Lay the metal part of the plug body on

E other unpainted part of the

the flywheel or s
motor, being
careful that the
metal part of
the plug body
only touches
the motor and
that the porce-
lain part is
clear. If . the
spark jumps in
short jerks be-
tween the inner
end of the por-
celain and the
interior of the
plug body it
is sooted and
needs cleaning.
If it jumps at
the points as it
should do, the
trouble is elsewhere; probably at the battery,
loose connecting wires, or the vibrator of the
coil is not properly adjusted.

To clean a spark plug properly use a 50 per
cent solution of hydrochloric (muriatic) acid.

SPARK PLUGS

A — Platinum point.
B— Thread.
C— Plug body.
D — Bushing.
B— Insulated terminal.
F — Porcelain bushing.
G — Expansion spring.
H — Asbestos washer.

K — Assembly nut.

258 THE AUTOMOBILE HAND-BOOK

washing the points of the plug with a tooth
brush, occasionally dipping the plug into the
a<:id. After cleaning the spark plug in thia
manner rinse it in water.

Spark Plugs, Constraction of. Two spark
plugs are shown
in Figure 80.
which, while
differing radi-
cally in their
construction,
effect the same
purpose, tliat
of producing a spark or arc in the combustion
chamber of the motor. The accompanying table
and n'ferencc to Figure 80, will fully explain the
construction of the spark plugs.

Cross-sections of four different forms of spark
plugs are shown in Figure 81. All are con-
structed with
a view to make
the outside or
extraneous path
caused by soot-
ing, as l»ng as SPARK PLUG

FiG. 82

to prevent if possible .short-circuiting of the plug
from tliis cause.

Figure 8% shows a fonn of sparit plug
in which two extra air-spaces are provided,

THE AUTOMOBILE HAND-BOOK

SPARK PLUG

Fic. 63

one between the center rod or terminal and
the porcelain bushing, and the other between the
porcelain bushing and the shell or body of the plug.

The spark plug shown in Figure 83 has a closed
chamber around and over
the center insulated rod or
terminal, this chamber is a
part of the body of the
plug and forms the other
terminal of the plug. It
acts as a small combustion
chamber and streams of
fire are supposed to be
thrown from the small open-
ings in the chamber, when
the arc or spark occurs
therein.

.\n exterior view of a
form of spark plug in gen-
eral use is shown in Fig-
ure 84.

SPARK PLUG

260 THE AUTOMOBILE HAND-BOOK

Spark plugs of American manufacture are
made with three different sizes of threads : One-
half inch pipe-size, the actual outside diameter of
which is 84-100 of an inch, with 14 threads per
inch. Three-quarters of an inch diameter, with
18 threads per inch, and 7-10 of an inch diameter,
with 17 threads per inch. The last named one
is the French or Metric standard thread.

Specific Gravity. In the absence of a proper
instrument, the specific gravity of gasoline or
any other liquid may be obtained as follows :

Weigh a certain quantity of distilled water at
4 degrees Centigrade, or 39^ degrees Fahrenheit.

Weigh the same quantity of gasoline or other
liquid under test.

Divide the weight of the liquid by the weight
of the water, and this will give the required
specific gravity of the liquid.

The specific gravities of various liquids are as

follows :

Alcohol at 15° C 0.794

Acid, nitric 1 . 217

Acid, sulphuric 1 .841

Ether at 15° C 0.720

Naphtha 0.848

Oil, linseed 0.94

Petroleum 0.878

Gasoline at 15° C 0.680 to 0.720

Water, sea, at 4° 1 .026

Water, pure, at 4° 1.0

Speed-change Gear — See Power Transmission

Devices.

Speed, Cyclic Variation of. The cyclic

irregularity of any reciprocating-piston motor is

THE AUTOMOBILE HAND-BOOK 261

defined as the ratio of the diflFerence between the
maximum and minimum velocity in any one
revolution to the mean velocity. The great
diflSculty in measuring this ratio is the continual
variation in the mean velocity. One system of
measurement uses a tuning-fork, which traces a
wavy line on a smoked cylinder attached to the
motor shaft. Another apparatus consists of a
disk attached to the motor shaft, and a fljrwheel
turning freely on the same axis. The disk and
flywheel are geared together by a planetary
gearing, whose axis, perpendicular to that of the
fljrwheel, carries a pencil point tracing on a rotating
drum. The flywheel is turned through the
planetary gearing, and takes up the mean speed
of the motor. As it is too heavy to follow the
cyclic variations in speed of the disk, these cause
the axis of the planetary gearing to move back-
ward and forward round the axis of the disk, and
the pencil point therefore traces a periodic curve
on the drum. This curve, however, does not
give the difference in velocity, but the relative
change in position of the disk and flywheel, and
the maximum difference in velocity must be
calculated from the two steepest tangents to the
curve. This apparatus is troublesome in the
calculation of results and is not sufficiently
sensitive for small irregularities. An apparatus
constructed on the principle of the von Altencck
transmission dynamometer is also used for this

262 THE AUTOMOBILE HAND-BOOK

purpose, a pulley attached to the motor shaft
being connected by a belt to a fljrwheel, which
takes up the mean velocity of the motor; the
variations in velocity produce variations in the
tension on the two sides of the belt, and an index
is arranged to measure these. The elasticity of
the belt renders this apparatus unsuitable for any
absolute measurements. Another device consists
of a heavy cylinder, mounted on an axis fixed to
the motor shaft by ball-bearings; the friction in
these causes it to take up the mean velocity. A
frame fixed to the shaft embraces the cylinder,
and carries a pencil point which is free to move
along the cylinder. A string attached to the
pencil passes over a pulley to a sleeve running
free on the axis; if this be held still, the string
winds up on it, and pulls the pencil along the
cylinder. As the motion of the cylinder is uni-
form, while the pencil follows the irregularities
of the motor, the latter traces a curve, from
which the cyclic irregularity can be reckoned.
This apparatus was found to work well, but was
not sufficiently sensitive for small irregularities.

The only method which has been found capable
of measuring a very small irregularity is to
employ a small independently excited dynamo
driven by the motor, and take its curve of volts
by means of a Joubert contact-maker and poten-
tiometer. As the volts arc proportional to the
speed, this gives also the curve of speed of the

THE AUTOMOBILE HAND-BOOK

263

motor. If there be no irregularities in the dynamo
voltage due to its construction, this method is
capable of giving very accurate results, but it is
troublesome and unsuited for practical work.

Speed in Miles per Hour. The following

table gives the speed in miles per hour, from 27.69
to 120 miles per hour, for a mile covered in any
given interval of time in minutes and seconds,

between 2:10 and 0:30.

Speed in Miles per Hour.

•2

-a

5||

^ GO 09

2s.

■3l

l|i

2:10

Si>eed
Miles
Hour.

a fi o

1:38

Speed

Miles

Hour.

1:15

Speed

Miles

Hour.

Speed

Miles

Hour.

27.69

36.73

48.00

69.23