Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1919-07-27
SlMPL|FIED LESSONS IN
CARE OF AUTOMOBILE.
Expert Describes Necessity for and
Method of Application of the
Clutch.
QUESTIONS AND ANSWERS
Automobile Owners Arc Given
Clarifying Replies to Their
Queries as TO Causes Of Their
Motor Troubles.

BYFREDERICK c. GUTcRRLICTS, NJ. f.
one iault which the gas engine
might be said to have. as compared
to the steam engine. is that it cannot
be started by simply turning n valve
as can the steam engine. but must
6rst be cranked. Because OF this fact
simply stopping the engine. and some
device must, therefore. he furnished by
which the engine can he d!sconnccted
to the rear wheels at the Will of the
operator.
The device used for this purpose is
called the clutch. There are hardly
two makes of clutch which are alike.
but those most used miEht be divided
tho disc and the three plate. Certain
cars have special designs. such as the
external contracting and inctrnal eX-
banding.
Let us see wha, the clutch mus. ac-
complish. 1t must instantly diSconnec:
the engine from the rear of the car
at the Will of the operator, and after
disconnectinG. II must not spin to any
exteE;, because II II does. it will he
difficult TO change gearss without the
edges Of them grinding or 'clashins";
1t must connect the engine and drive
wheels, but this must he done grad
uaily. as the car must he brought from
a zero speed through infinite small
speeds TO the required speeds.
Were 1t not for the last requirement.
the designing OF a clutch would he a
simple matter, as then some simple
positive device. such as n set of do ss"
or gears" could he used. but this re-
Quirement means ;hat n device which
Will permit certain amount OF slip
ping, which slipping can be controlled
~ the operator. must he used; or, in
other words. some holding force. the
holding power OF which can he varied
must be used The force OF friction"
is such force
Force OF Friction
You all know what friction is, but
few know that the force of frct ion
between two surfaces depends on two
things: The material of which the sur
faces are made. and the pressure which
holds the surfaces against one an
other AS there are many ways In
which pressure can be varied. the prob
lem OF clutch design resolves into hav-
Ing two surfaces pressed together
with means for VARYING the pressure
and 10 having the material such that
the holding power between the two
surfaces will be great for small
pressure.
Having decided to use a friction
clutch. let's proceed to design one.
What materials shall We use for the
friction surface?
Leather against steel Inns a high
friction, so lets use that. What shape
shall the surface have? We find that
when one cone is pressed into another.
there is a sort Of inclined plane" ac-
ton, so that slight pressure when in
sorting one cone into the other. will
against their sides. so let us use sec
tions OF cone for the engaging sur
faces.
What shall We use to exert the pres
be able to vary this pressure and we
find that a spring is ideal for this pur-
pose
As shown ny Diagrams.
Let us make drawing of our de-
Vice as decided upon so far as Fig l.
Here the inside Of the nywhce, is
turned or cut out 50 as 10 have the
shape of the inside OF "A cone, while
can be pressed into II, by the spring
c. AS the nywheel is attached TO
the engine. the clutch Il must he con-
nected to the rear OF the car. Let us
do this by r!vctinG the casing or D.
Fig. 10 the clutch and have the other
end fastened 10 a gear in the trans
mission, or 20 tho propeller shaft as
desired AS the clutch must he pulled
out, an arrangement TO allow for this
must be used in tho connection so let
us have a SQUARE hole in the. end and
hole. as shown by +.
How shall We pull tho clutch out OF
us put n collar on the casing and then
arrange lever. operated bv foot
pedal SO as TO press against this. and
thus pull the clutch hack against tho
pressure OF the spring. g is tho col
lar, and u the lever, while Il" is the
foot pedal.
Practice has shown that one other
shown, will nave 4. t,en,l$ncy '1 10 ma ks
harsh engaSrfnerit To overcome
this, designers inserted small pieces
or cork under The leather. and latter
small springs. mus causing iittIa
raised. but Welding. knobs on the
leather. Th"s" inserts" will give the
Siutch Nclv"tr or cai's-paw grip
They are shown In Fig 2 l. is n
spring insert, while NJ is one Of cork
AS a rule. these inserts have m adj
1ustment but. in some cases an ar
arrangement x made 10 adjust the ten
sion OF the insert spring
AS the clutch is connected 10 one OF