1. To engage and disengage the transmission from
engine to the remaining parts of transmission. (To
allow the engine to be separated from rest of the
(a) Starting and running the engine at a sufficiently
high speed lo generate sufficient power necessary for
moving the vehicle from rest.
(b) Shifting the gears so that damage to gear teeth can
(c) Stopping the vehicle after applying brakes.
2. The second function of the clutch is to allow the
engine to take up the driving load of the vehicle
gradually and without shock.
Requirements of clutch
1. Transmit maximum torque of the engine.
2. Engage gradually to avoid sudden jerks.
3. Able to dissipate large amount of heat generated during clutch
4. Dynamically balanced, particularly in the case of high speed
5. To damp vibrations and to eliminate noise produced during
6. As small as possible so that it will occupy minimum space.
7. Easy to operate requiring as little exertion on the part of the
8. Light in weight.
9. Trouble free and have longer life.
10. Easy to inspect, adjust and repair.
POSITIVE ENGAGEMENT ONE WAY GRADUAL ENGAGEMENT
CLUTCH CLUTCHES CLUTCH
CONE DISC CENTRIFUGAL SEMI ELECTRO-
INT EXT SINGLE MULTI DIAPHRAGM
SINGLE PLATE CLUTCH
(i) Mill board type: This material is in the form of sheets made of asbestos and
treated with certain impregnates. From the standard sheet we can cut facing discs
according to different size requirements.
(ii) Moulded type: When asbestos fibers are mixed with a suitable binder and
heated to a definite temperature and then moulded in dies under pressure, this type
of friction material is called “moulded type”. To improve the wearing qualities of
the material (sometimes metallic wires are also inserted). This type of lining is
stronger, dense and capable to transmit heavy loads through it. The disadvantage is
only this that moulding for each size lining is very costly.
(iii) Woven type: This type of material is made by spinning threads from asbestos
fibres, weaving this thread into a cloth and then impregnating it with a bonding
material. This type of material is further divided into classes; (a) the solid woven
variety is woven to the required thickness in one operation and has a greater
mechanical strength; (b) the laminated variety consists of layers of cloth placed on
top of each other and held together by the bonding material. Both types may
incorporate brass wire.
CLUTCH LINING MATERIALS
Common materials used for clutch lining are:
(i) Asbestos: It can be used at high temperature also
and linings of this material have coefficient of friction
of about 0 2.
(ii) Reybestos and Ferodo: These materials are most
suitable and generally used for clutch friction linings
and have a co efficient of friction of about 0.35.
(iii) Leather: The co-efficient of friction between dry
leather and iron is 0.27.
(iv) Cork: The co-efficient of friction between cork and
steel or iron is 0.32.
(v) Fabric: This material has co-efficient of friction about
0.4, but it cannot be used a high temperature.