BITS edu campus Theory Of Machines

Presented By: Mechanical Department Division : 2 Batch : C Patel Krunal Bipinbhai [130050119080] Patel Dhruval Mukeshbhai [130050119533] Mechanical Department Division : 2 Batch : C GUIDED BY – NIRMAL KUMAR KUSHWAHA

Clutch

Intro A Clutch is a machine member used to connect the driving shaft to a driven shaft, so that the driven shaft may be started or stopped at will, without stopping the driving shaft. A clutch thus provides an interruptible connection between two rotating shafts. Clutches allow a high inertia load to be stated with a small power. A popularly known application of clutch is in automotive vehicles where it is used to connect the engine and the gear box. Here the clutch enables to crank and start the engine disengaging the transmission Disengage the transmission and change the gear to alter the torque on the wheels. Clutches are also used extensively in production machinery of all types

Function Of Clutch Clutch is used to transmit power from driven shaft to driving shaft. In automobiles, where vehicle can be stopped for a while or to change the gear, the requirement is that the driven shaft should stop but the engine should run naturally under the no load condition. This is achieved by using clutch mounted between engine shaft and gearbox shaft and which is operated by a lever.

Types Of Clutch

Friction Clutch Friction clutches transmit torque by virtue of frictional force devloped.Fig shows friction cluch which consist of two plates.One of them is keyed to the driving shaft and other is free to slide axizlly on the driven spindle shaft. Frictional lining is provided on the driven shaft.Axial force applied by the compression spring will hold two plates together. the torque or power is transmitted between driving and shaft because of frictional force in between surface in contact. These clutches are not positive clutch since slip may occur. Friction clutch can be engaged while the driving member is rotating and the driven member is sationary.It is used where partial or full power to be transmitted and ferequent engagement is required.

Fig:Friction Clutch

Advantages and Disadvantages of friction clutch: Frequent engagement and disengagement is possible. It can transmit partial or full power. It can engaged when driving shaft is rotating and driven shaft is stationary. It is very easy to operate. Disadvantages: Friction clutches will not give positive engagement. Due to slip between contacting surface,heat is generated during engagement.

Single Plate clutch Design of clutch plate

Single Plate clutch Single Plate clutch W=total axial load R1=External radius of clutch plate R2=internal radius of the clutch plate P=intensity of pressure between contacting surfaces. µ=coefficient of friction between contacting surfaces Single Plate clutch

Single Plate clutch Consider a elemental ring of radius ‘r’ and thickness δr on the contacting surface. therefore, Area of the ring on contacting surface is, Axial load on the ring is, δW=pressure×Area of the ring

Single Plate Clutch Frictional resistance offered by ring is, Frictional torque acting on the ring is, ……(1)

Single Plate Clutch Torque transmitted by single plate clutch is obtained by considering following two assumptions (a)uniform pressure theory (b)uniform wear theory

Single Plate Clutch (a)uniform pressure theory: Assuming that the intensity of pressure over the entire contacting surface area is constant, Then, p=constant Total torque transmitted by single plate clutch can be obtain by integrating Equation ….(2)

Single Plate Clutch (1)within limit R2 to R1 we [∵p=Constant]

Equation (A) gives the torque transmitted by single plate clutch due to friction considering uniform pressure theory. Single Plate Clutch …….(A)

Single Plate Clutch (b) Uniform Wear Theory In this theory, we are considering that wear which take place is uniform over the entire contacting surface i.e. P.r=constant P.r=C P=C/r …...(3)

Single Plate Clutch Axial load acting on the ring is δW=p 2π r δr δW=2 π C δr …(4) Integrating above Equation(4) within limit we get,

Single Plate Clutch ……….(5) We know that frictional torque acting on ring is, …….(6)

Single Plate Clutch Torque transmitted by single plate clutch can be obtain by integrating the Equation (4 ) within the limit R2 to R1 we get,

Single Plate Clutch This is the torque transmitted by single plate due to friction considering uniform wear theory.

Single Plate Clutch Power transmitted by single plate clutch is given by,

Multiplate clutch is used when large torque is to be transmitted e. g Multiplate clutch is used when large torque is to be transmitted e.g. motor cars and machine tools. Multiplate Clutch

A multi plate clutch is shown in fig A multi plate clutch is shown in fig.It cosist of two sets os plate the driving plates and driven plates arranged alternately,driving shaft,spring,soindle driven shaft etc.it cosist of more than one driving as well as drive plate.So the number of pair of contacting surface is more than two. As shown in fig friction plates are splined on their outer circumference and engage with corresponding splines on the casing.Friction plates having ring of friction on both sides expect the first plates which is adjacent to casting.This plate is having friction lining in one side. The pressure plates as shown in fig.are splined on their inner circumference and engage with corresponding splines on the driven shaft.Both friction plates and pressure plates are free to slides axially. Multiplate Clutch

Multiplate Clutch

Multiplate Clutch Application of multi plate clutch: Multi plate is used when large torque is to be transmitted. E.g- Motor cars and Machine tools. 2. Multi plate is used where compact construction is required. E.g- scooter and Motorcycles. For uniform pressure theory, For uniform wear theory,

Multiplate Clutch Notes: In case of new clutch ,the intensity of pressure is uniform along the surface of clutch but in case of old clutch uniform theory is more correct. For single plate clutch normally both sides of the plate are effective .there for single plate clutch has two pairs of contacting surface i.e. n=2. In actual practice, usually the theory of uniform wear is used in analysis of clutch. Multiplate Clutch

Intensity of pressure is maximum at the inner radius R2 of the friction or contact surface, Intensity of pressure is minimum at the inner radius R1 of the friction or contact surface, Multiplate Clutch

Multiplate Clutch In mutilate disc clutch no of disc on driving shaft no of disc on driven shaft So no. of pairs in contact, Multiplate Clutch

Multiplate Clutch

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