CLUTCH
Definition :-
A clutch is a machine member used to connect a driving shaft to a driven shaft so that the driven shaft may be started at will , without stopping the driving shaft .
The use of a clutch is mostly in automobiles .
TYPES OF CLUTCH
1. Positive clutch
2. Friction clutch
1. POSITIVE CLUTCH
- The positive clutch is used when a positive drive is required .
- The simplest type of a positive clutch is a jaw or claw clutch .
JAW CLUTCH
The jaw clutch permits one shaft to drive another through a direct contact of interlocking jaw . It consists of two halves , one of which is permanently fastened to the driving shaft . The other half of the clutch is movable . and it is free to slide axially on the driven shaft .
2. FRICTION CLUTCHES
A friction clutch is a principal application in the transmission of power of shaft and machines which must be started and stopped frequently .
Its application is found in cases in which power is to be deleivered to machine partially of fully loaded .
MATERIAL FOR FRICTION SURFACES
- It should have a high and uniform coefficient of friction .
- It should not be effected by moisture and oil .
- It should should have high heat conductivity .
- It should have high resistance to wear and scoring .
TYPES OF FRICTION CLUTCH
1 . Disc or Plate Clutch
2 . Cone clutch
3 . Centrifugal clutch
1 . SINGLE OR PLATE CLUTCH
A plate clutch is consists of a clutch plate whose both sides are faced with a frictional material . It is mounted on the the hub which is free to move axially along the splines of driving shaft . The pressure plate is mounted inside the clutch body which is bolted to the flywheel . Both the pressure plate and flywheel rotate with the engine crankshaft .
2 . CONE CLUTCH
A cone clutch is used in automobiles . but now a days , it has been replaced completely by disc clutch . It consists of one pair of friction surface only . In a cone clutch the driver is keyed to the driving shaft by a sunk key and has an inside a conical surface which has fit exactly fit into the outside of conical surface of the driven .
Due to the fritional resistance set up at the contact surface , the torque is transmitted from one shaft to another . In some cases , the spring is placed around the driven shaft in contact with the hub of the driven .
3 . CENTRIFUGAL CLUTCH
The centrifugal clutches are usually incorporated into the motor pulley . It consists of a number of shoes on the inside of a rim of the pulley . The uter surface of the shoes are covered with a friction material .
The springs exerts a radialy inwards force which is assumed to be constant . The weight of the shoe when revolving cause it to exert a radially outward force .
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