Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1919-08-10
.SIMPL|F|ED LESSONS IN
CARE OF AUTOMOBILE
Purpose and Principle of Transmits
sion Described by Engineer
81 Expert Gucrrlich.
POWER REQUIRED IN CLIMBING
Engines Must BE Built to Care For
Ascending Hills and Making Turns.
More Effort to Start Car Than to
Keep Going.

When the designer Of an automobile
has TO decide upon the size of the en-
gine. he must consider what the engine c
must do. Let US briefly look into this.
When the car is driven along a level
road. the engine must overcome the
friction OF the bearings in the car. and
the resistance OF the wind. For this
purpose an engine OF a certain bore
and turning power and which Will give
certain minimum speed Will suit
When the car is ascending a hill.
the engine will have TO overcome the
friction and wind resistance as before.
but. also. ii Will have 10 lift the car
from the lower to the higher level.
So engine OF much larger turning
power. and. therefore. bore. will be
Have you ever watched men push
Ing an auto, or wagon. about? 1t
may require the full strength OF three
men to start il moving, hut as soon
as II is in motion, one man Will let
go. and when the car has some speed
third will he able TO keep the in
motion with comparatively little et-
for, 10 Thus more powsrful engine
than for keeping it going.
When More Power Required.
So we find that much greater turn
Ing power is required from the engine.
When i, h is beine s,anied into mo-,
The car must be able 10 ascend hills
and start into motion, but 40 per cent
This means that If the engine is built
large enough to climb the hills. for 90
per cent of the time an excess weight
Of engine will have to be carried, with
the extra cost of fuel. etc, which would
result thcrefrom
good designer will try to find some
adding some device which will enable
the engine to also take care OF the
hill climbing and starting into motion.
engine and the rear wheels will accom-
plish this. AS system. or train OF
gears. Is system OF levers. the prob
gears between the engine and rear
wheels. or. in other words having the
power Of the engine transmitted to the
rear wheels by them. Thus We have
the transmits Sion.
Let US see how the gears act as
levers
Principle Involved.
Have you ever watched safe-movers
bar! What they. do is shown in Fig.
L Here the point a is the ground.
II ne distance + is ten times as great
a pressure Of 700 pounds a, D. can
exert pressure OF 1000 pounds at T.
Let us now assume. that a is the
the propeller shaft OF the automobile.
and that is on the circumference OF
a gear B fastened to this shaft as
shown in Fig. >, II il takes a pres
sure Of 1000 pounds on the circum-
ference Of the shaft at f TO drive the
driving the gear B by the gear + ana
making the engine OF such a size tina,
a. pressure Of 100 pounds is e1erted b,
the gear F on the gear p. the car will
be driven up this steepest grade
The room for the transmission OF
the automobile is necessarily limited.
and II the single gear. As shown, were
n Nm
than can be allowed for it. So the
way of using gears which will take
up less room. and yet give the re-
CURED leverage. The natural solution
is TO have sets OF gears, one set. say,
to give a leverage OF 5, the other OF
l-3, giving total leverage OF 3
times of 10.
Let US. therefore, make the gear
B smaller in diameter. say only Ia
times that OF the shaft r, and then
US move the shaft connected TO the
propeller shaft TO the position shown
by II, Fig. .. BY now placing gear.
j. having diameter times that Of
the shaft II, md driving this gear BY
the gear +, we will have two sets OF
small gears. one giving a leverage OF
3 to ] and the other OF l-3 to /, or
total OF 10.
Thus II 1000 pounds is required at
pounds, will be. required a, X. the
circumference OF the gear j. and as
the gear is l.3 the diameter OF
the gear +, =. wi,lthlve a leverage Of
l-3 TO = ..rft!' only 100 pounds will
DC required AT the point -, which is