29-09-2012, 01:17 PM
Different types of clutches
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CLUTCH
A clutch is a mechanical device which provides for the transmission of power (and therefore usually motion) from one component (the driving member) to another (the driven member).
TYPES OF CLUTCHS
(a) Friction Clutch : It may be
(i) single plate clutch,
(ii) multi-plate clutch, or
(iii) cone clutch.
(b) Centrifugal clutch.
© Semi-centrifugal clutch
Principle of friction clutch
It operates on the principle of friction. When two surfaces are brought in contact and are held against each other due to friction between them, they can be used to transmit power. If one is rotated, then other also rotates. One surface is connected to engine and other to the transmission system of automobile. Thus, clutch is nothing but a combination of two friction surfaces.
SINGLE PLATE CLUTCH
A single plate is commonly used in cars and light vehicles. It has only one clutch plate which is mounted on the splines of the clutch shaft. A flywheel is mounted on the crankshaft of the engine. A pressure plate is connected to the flywheel through the bolts and clutch springs. It is free to slide on the clutch shaft with the movement of clutch pedal. When clutch is in engaged position, the clutch plate remains gripped between flywheel and pressure plate. Friction linings are provided on both the sides of clutch plate. On one side clutch plate is in touch with flywheel and on other side with pressure plate. Due to friction on both sides, the clutch plate revolves with engine flywheel. Therefore, clutch transmits engine power to clutch shaft. Clutch shaft is connected to transmission (or gear box) of automobile. Thus, clutch transmits power from engine to transmission system which inturn rotates wheels of engine.
When the clutch plate is to be disengaged, the clutch pedal is pressed. Because of this pressure plate moves back and clutch plate is disengaged from flywheel. Thus, clutch shaft stops rotating even if engine flywheel is rotating. In this position, power does not reach the wheels and vehicle also stops running.
Multiplate clutch
Multi-plate clutch consists of more than one clutch plates contrary to single plate clutch which consists of only one plate. Friction surfaces are made in case of multi-plate clutch. Due to increased number of friction surfaces, a multi-plate clutch can transmit large torque. Therefore, it is used in racing cars and heavy motor vehicles witch have high engine power. The clutch plates are alternatively fitted with engine shaft and the shaft of gear box. He plates are firmly held by the force of coil springs and they assembled in a drum. One plate slides in the grooves on the flywheel and the next plate slides on spines provided on pressure plate. Thus, each alternate plate slides in grooves on the flywheel and the other on splines of pressure plate. If we take two consecutive plates, then one has inner and other has outer splines.
When the clutch pedal is pressed, the pressure plate moves back against the force of coil spring, hen the clutch plates are disengaged and engine flywheel and gear box are decoupled. However, when clutch pedal is not pressed the clutch remain in engaged position and the power can be transmitted from engine flywheel to the gear box.
Cone clutch
Cone clutch is the type which consists of inner and outer conical surface. Its outer cone is keyed with driving shaft and the inner cone is free to slide on the driven shaft axially because of splines. Axial force which is required to connect clutch is provided with the help of helical compression spring. In this connecting position, power is transmitted from driving shaft to outer cone with the help of key. After that power is transmitted from outer cone to inner cone with the help of friction.
In the end power then transmit from inner cone to driven shaft by using splines. For disconnecting the clutch, fork is placed in shifting collar to shift it axially towards right side. This process releases pressure between both cones and no transmission of torque occurs.
For friction lining in inner cone, we use leather, asbestos or cork. Conical force results into notable frictional force because of the action of wedge. The angle which is recommended for semi cone is 12.50. In construction cone clutches are very simple and easy to disconnect. But the major drawback for using this cone is the strict requirement for coaxiality of two shafts.