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					            CLUTCHES




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FUNCTIONS
 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
     transmission system)
           (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
            be avoided.
           (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.
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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
     operation.
  4. Dynamically balanced, particularly in the case of high speed
     engine clutches.
  5. To damp vibrations and to eliminate noise produced during
     power transmission.
  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
     driver.
  8. Light in weight.
  9. Trouble free and have longer life.
  10. Easy to inspect, adjust and repair.
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                                     CLUTCH


             POSITIVE ENGAGEMENT      ONE WAY        GRADUAL ENGAGEMENT
             CLUTCH                   CLUTCHES       CLUTCH




                                FRICTION                              FLUID
                                CLUTCH                                CLUTCH




            CONE     DISC     CENTRIFUGAL        SEMI            ELECTRO-
                                                 CENTRIFUGAL     MAGNETIC



            INT    EXT      SINGLE          MULTI        DIAPHRAGM




                            DRY                                WET


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SINGLE PLATE CLUTCH




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CLUTCH PLATE




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DIAPHRAGM CLUTCHES




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CENTRIFUGAL CLUTCH




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MULTIPLATE CLUTCHES




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MULTIPLATE CLUTCH




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CONE CLUTCH




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SEMICENTRIFUGAL CLUTCH




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CENTRIFUGAL CLUTCH




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CENTRIFUGAL CLUTCH




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ELECTROMAGNETIC CLUTCH




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FRICTION MATERIALS
  (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.
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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.

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            Any Questions?




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