Frictional clutch

GANDHINAGAR INSTITUTE OF TECHNOLOGY

THEORY OF MACHINES (2151902)Active Learning Assignment

On

MECHANICAL DEPARTMENT

FRICTIONAL CLUCHES PREPAIRED BY: MANAV SONANI (140120119223)

CHANDRESH SUTHAR (140120119229)

GOVIND TADE (140120119230)

GUIDED BY:

PROF. VIPAL PANCHAL

CONTENT

• Introduction to clutch • Types of clutch• Disc clutch Single plate clutch Multi plate clutch• Cone clutch• Centrifugal clutch

WHAT IS CLUTCHES ?•A Clutch is a mechanical device that engages and disengages the power transmission , especially from driving shaft to driven shaft.

•In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). In these devices, one shaft is typically attached to an engine or other power unit (the driving member) while the other shaft (the driven member) provides output power for work.

TYPES OF CLUTCHES1)Mechanical clutches2)Pneumatic clutches3)Hydraulic clutches4)Electromagnetic clutches

Mechanical clutches1)Positive contact clutchesi. jaw clutchesii.toothed clutches2)Friction clutchesDisc clutches • Single plate clutches • Multi plate clutches Cone clutchesCentrifugal clutches

SINGLE PLATE CLUTCH

USED IN CARS AND LIGHT VEHICLES.

IT HAS ONLY ONE CLUTCH PLATE WHICH IS MOUNTED ON

THE SPLINES OF THE CLUTCH SHAFT.

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.

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

1R1R

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

δrr 2πpδW

Single Plate Clutch

•Frictional resistance offered by ring is,

•Frictional torque acting on the ring is,

δWμ Fr

δrr pμ 2πδr)r 2π μ(pFr

r 2

r

rr

δr pμ 2πδr.rr pμ 2πT

r FT

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,

•Total torque transmitted by single plate clutch can be obtain by integrating Equation

Then, p=constant

22

21 RRπW

area surface contactingloadp

Single Plate Clutch

•(1)within limit R2 to R1 we

[ p=Constant]∵

1

2

R

R

2T

0r δr r pμ 2πΤ

1

2

R

R

2T

0r δr rpμ 2πΤ

32

31

R

R

3

RR pμ π32

3rpμ 2πΤ

2

1

…….(A)

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

32

312

22

1

RRRRπ

Wμ π32Τ

2

22

1 RRπWp∵

22

21

32

31

RRRRμ W

32Τ

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,

δr C 2π rCδW

w

0

R

R

1

2

δr C 2πδW

Single Plate Clutch

•We know that frictional torque acting on ring is,

……….(5)

…….(6)

21

21RR

RR 2πWC

RR C 2r C 2πW 1

2

δr r Cμ 2πΤδrrrCμ π2Τ

δr r pμ 2πΤ

r 2

r

2r

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,

2

RRCμ 2π2rCμ 2πΤ

δrr Cμ 2πΤ

δrr Cμ 2πΤ

22

21

R

R

2

R

R

T

0r

R

R

T

0r

1

2

2

2

2

2

Single Plate Clutch

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

μW π21Τ

RRRRμW π

21Τ

RRRR2π

Wμ πΤ

21

22

21

22

21

21

Single Plate Clutch

•Power transmitted by single plate clutch is given by,

rpmin shaft of SpeedN where,

Watt60NΤ 2πP

Τ ωP

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.

For multiplate clutch•For uniform pressure theory,

•For uniform wear theory,

22

21

32

31

RRRRμ W

32nΤ

21 RRμW 21nΤ

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.

•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,

2max2max R

CP OR CRP

1max1max R

CP OR CRP

In mutilate disc clutch no of disc on driving shaft no of disc on driven shaft

So no. of pairs in contact,

1nnn 21

1n2n

CONE CLUTCH

CONE CLUTCH

• A cone clutch serves the same purpose as a disk or plate clutch. However, instead of mating two spinning disks, the cone clutch uses two conical surfaces to transmit friction and torque. The cone clutch transfers a higher torque than plate or disk clutches of the same size due to the wedging action and increased surface area.

CONE CLUTCH

• Cone clutches are generally now only used in low peripheral speed applications although they were once common in automobiles and other combustion engine transmissions. They are usually now confined to very specialist transmissions in racing, rallying, or in extreme off-road vehicles, although they are common in power boats.

CONE CLUTCH

Notation of cone clutch

CONE CLUTCH

An element of cone clutch

CONE CLUTCH

CONE CLUTCH

CONE CLUTCH• According to uniform pressure theory,

(where p is constant)

• According to uniform wear theory,(where p*r is constant)

Centrifugal Clutch

Centrifugal clutch

Driving shaft

Driven shaft

Friction lining

Total friction torque , T = nµR(F-P)

F=mrω2

ω

ω

CENTRIFUGAL CLUTCH

CENTRIFUGAL CLUTCH

• A centrifugal clutch works on the principle of centrifugal force.

• The clutch's purpose is to disengage when the engine is idling so that the chain does not move .

• These clutches are particularly useful in internal combustion engines, which can not be started under load.

•The clutch consists of three parts:

•An outer drum that turns freely - This drum includes a sprocket that engages the chain. When the drum turns, the chain turns. •A centre shaft attached directly to the engine's crankshaft - If the engine is turning, so is the shaft. •A pair of cylindrical clutch weights attached to the centre shaft, along with a spring that keeps them retracted against the shaft

CENTRIFUGAL CLUTCH

• There are several advantages to a centrifugal clutch

• It is automatic. (In a car with a manual transmission, you need a clutch pedal. A centrifugal clutch doesn't.)

• It slips automatically to avoid stalling the engine. (In a car, the driver must slip the clutch.)

• Once the engine is spinning fast enough, there is no slip in the clutch.

• It lasts forever.

CENTRIFUGAL CLUTCH

CENTRIFUGAL CLUTCH

CENTRIFUGAL CLUTCH• The centrifugal force acting on each shoe,

• Just before engagement with shoe,

CENTRIFUGAL CLUTCH• During running condition, the net force