Clutch

•Transmit rotary motion of one shaft to another when desired

•Couple the engine from transmission while

1)shifting gears

2)starting vehicle from rest

Types Of Clutch

Types of Clutches

Positive Clutch

Friction Clutch

Plate Or Disc Clutch

Single plate clutch

Multiplate Clutch

Cone ClutchCentrifugal

Clutch

Single plate clutch

Design of clutch plate

Diagram

oR

iRiR

oR

r

Uniform Pressure

Theory

Uniform Wear

Theory

)(

FP

22io RR

)R-r(R2

FP

io

)R(R

)R(R

3

2FT

2i

2o

3i

3o

)RR(

2

1FT io

Where,

P=normal pressure

F=axial force

=coefficient of friction

between the surfaces

T=friction torque

radiusinner R

radiusouter R

i

o

Where

Pr=constant

Multiplate Clutch

• Multiplate clutch is used when large torque is to be

transmitted e.g. motor cars and machine tools

Exploded view of multi-plate clutch

Uniform pressure theory Uniform Wear theory

2i

2

o

3i

3o

RR

RR

3

2Fμ nΤ io RR

2

1μFnΤ

1-nnn 21

n1=number of plates on driving shaft

n2=number of plates on driven shaft

n =number of pair of active surfaces

Cone Clutch

• Contact surfaces are in form of cones

• Normal force on contact surface is increased

• More torque is transmitted

=semi-cone angle, w=width of cone

)RR(

)R(R

3

2F

sin

1T

2i

2o

3i

30

)RR(

2

1F

sin

1T i0

Uniform pressure

theory

Uniform

wear theory

iR

oRw

R-Rsin

io

Centrifugal clutch

•Clutch is engaged only after a particular speed of motor

m=mass of each shoe R=inner radius of pulley rim

r=distance of centre of mass of p=max pressure intensity

each shoe from shaft axis n=number of shoes

=normal shaft speed ’=speed at which shoe

=angle shoe subtends at centre moves forward

=coefficient of friction between shoe and rim

l=contact length=.R , b=contact width

Total frictional torque=

Also,

R.n).'mr( 22

p.l.b)'mr( 22

Note:

1) New clutch - Uniform Pressure theory

2) Old clutch - Uniform Wear theory(used more often)

3) Single plate clutch - normally both sides of the plate are

effective - two pairs of contacting surface :- n=2.

DiagramCentifugal clutch