Clutch

Ch-2 Clutch
By, Deep Shah
Lecturer at IETI, Kheda (683)
Sub: ATM (3330202)
auto-ieti.blogspot.com

Introduction of Powertrains
 A Transmission system uses a clutch, gear box, propeller shaft
and a differential gear to transmit power from engine to the road
wheels
 The power may be transmitted to rear or front or all four wheels
depending on the drive used
 The clutch and gear box varies the ratio of torque output to
torque input
 The propeller shaft transmits final torque to the rear axle from
gear box
 A differential gear equally distributes the final torque between
the road wheels.

Functions of Transmission System
 It disconnects engine from driving wheels when
required
 The engine is connected to driving wheels when
required
 It changes ratio of torque output to torque input, as
desired
 It turns the drive through a right angle

What is CLUTCH....???

CLUTCH
 Mechanism which enables rotary motion of shaft to be
transmitted to the second shaft axis ,which is
coincident with the first
 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 when ever needed, without
stopping the driving shaft.

Function of Clutch
 Starting and warming up the engine
 To engage the first gear, to start moving the vehicle from rest
 To facilitate gear shifting easily without noise and damage
 To stop the vehicle by applying the brakes
 To allow the engine taking load without shock and jerk as well
as gradually
 To run the engine in ideal condition

Requirement of Clutch
 Torque transmission: The clutch must be able to transmit
maximum torque of the engine
 Gradual engagement: The clutch should engage gradually to
avoid sudden jerks
 Heat dissipation: The clutch should be able to dissipate large
quantity of heat which is generated during the clutch operation
due to friction
 Dynamic balancing: The clutch should be dynamically balanced.
This is particularly required incase of high speed engine
clutches.
 Size: The clutch should be as small as possible so that it
occupies minimum spaceauto-ieti.blogspot.com

 Vibration damping: The clutch should have suitable mechanism
to damp vibrations and to eliminate noise produced during
power transmitted.
 Inertia: The clutch rotating parts should have minimum
inertia.( Otherwise when clutch plate is released for gear
changing, clutch plate will keep on spinning)
 Clutch free pedal play: To reduce effective clamping load on
carbon thrust bearing
 Ease of operation: As clutch transmits higher torque , its
disengagement should not tiresome the driver

Location of Clutch

Classification of Clutches
Clutch
Gradual Engagement
Clutch
Fluid Clutch/Fluid
flywheel
Automatic Clutch
Friction Clutch
Diaphragm Clutch
Cone Clutch
Disc Clutch
Single Plate Clutch
Multi Plate Clutch
Centrifugal Clutch
Semi-Centrifugal Clutch
Positive Clutch

Positive Clutch
 In this type of clutch, the engaging clutch surfaces
interlock to produce rigid joint they are suitable for
situations requiring simple & rapid disconnection,
although they must be connected while shaft are
stationary & unloaded.
 The jaw may be square jaw type or spiral jaw type.
 They are designed empirically by considering
compressive strength of the material used.

Positive Clutch

Positive Clutch
Advantages
 Simple
 No heat generated
 No slip
 Compact
 Low cost
Disadvantages
 Must be connected when
shaft is unloaded

Friction Clutch
 Friction Clutches work on the basis of the frictional
forces developed between the two or more surfaces in
contact.
 Friction clutches are usually over the jaw clutches due
to their better performance.
 The major types of friction clutches are
Dry Clutch
Wet Clutch

Dry Clutch & Wet Clutch
Dry Clutch
 When the oil is not applied on the
clutch surfaces or the clutch is not
sinked or drown in oil during its
working, then it’s called dry
clutch.
 This type of clutch has various
types of arrangements.
 Single Plate Clutch
 Multi Plate Clutch
 Centrifugal Clutch
 Cone Clutch
Wet Clutch
 This type of clutch is works when it
is sinked in oil, hence it is called
wet clutch.
 The different forms of wet clutch
are multi-ply clutch and fluid
flywheel.

Single Plate Clutch

Single Plate Clutch
 Working- The diagram shows the pressure plate
pulled back by the release levers against the
compression springs; so that the friction linings on
the clutch plate are free of flywheel and pressure
plate. The flywheel rotates without driving the
clutch plate and hence the shaft.
 When the pressure of the thrust race is released
the compression springs are free to move the
pressure plate to the left bringing it in contact
with the clutch plate.
 The pressure plate moves to the left, sliding the
clutch plate on its splined hub, along the driven
shaft until the friction lining touches the flywheel.
 The compression springs now cause the linings to
be gripped between the pressure plate and the
flywheel and the friction between the linings and
flywheel and pressure plate causes the clutch
plate to revolve, turning the driven shaft.

Single Plate Clutch
Advantages
 Simple Construction
 Heat dissipation is fast
 Maintenance is easy
 Overhauling is easy
Disadvantages
 Torque transmission
capacity is less
 Lesser lining life
 Less load capacity
 Gear changing speed is
less

Multi Plate Clutch
 Multi plate clutch is used when
 Large torque is to be transmitted e.g. Heavy vehicles and machine tools
 Compact construction is required e.g. Scooters and motor cycles
 When a great amount of torque is to be transmitted, instead of
single plate a number of friction plates are employed. This
increases the number of mating friction surfaces, hence it is
called multi plate clutch.
 These clutches are used in heavy commercial vehicles, racing
cars and motor cycles for transmitting high torque.
 In this friction rings are splined on their outer circumferences
to mate with corresponding splines on the bore of the housing
and are free to slide on the splines.
 The friction material therefore rotates with the housing and
engine shafts.

Multi Plate Clutch

Multi Plate Clutch
Advantages
 Torque transmission
capacity is more
 Its size can be kept
constant
 Lining life is more
 For same torque capacity,
its size can be taken
small
 Gear can be shifted
quickly
Disadvantages
 Constriction is complex
 Heat dissipation is slow
 Maintenance is difficult
 Overhauling is difficult

Single Plate Clutch
 Torque transmission capacity
is less
 Heat dissipation is fast
 Lining life is less
 For same torque capacity, its
size can be taken more
 Maintenance is easy
 Overhauling is easy
 Used in small car & vehicles
having less load capacity
Multi Plate Clutch
 Torque transmission capacity
is more
 Heat dissipation is slow
 Lining life is more
 For same torque capacity, its
size can be taken small
 Maintenance is difficult
 Overhauling is difficult
 Used in the vehicles
transporting too heavy load

Diaphragm Clutch

Diaphragm Clutch
 Release lever is not required because in this clutch
instead of coil spring, the diaphragm spring is used.
 The diaphragm spring is self provides the series of lever.
 The diaphragm spring clutch is more suitable in most of
the front wheel drive motor cars.
 Diaphragm spring is compact, hence it can be
accommodated in a small bell housing.
 It does not produce sharp and rattling sound as rotating
parts in it are less.
 The design provides the balance of clutch assembly in all
operating condition.

Centrifugal Clutch
 A centrifugal clutch is a clutch that uses centrifugal force to connect two
concentric shafts, with the driving shaft nested inside the driven shaft.
 It consists of number of shoe on the inside of a rim of pulley. The outer
surface of pulley is covered with friction material.
 These shoes are moves radially in guides.

Centrifugal Clutch
 As the speed of the shaft increase, the centrifugal force on the shoes
increase.
 When the centrifugal force is less than the spring force, the shoes
remain in the same position as when the driving shaft was stationary,
but when the centrifugal force is equal to the spring force, the shoes
are just floating.
 When the centrifugal force exceeds the spring force, the shoes move
outward and come into contact with the driven member presses
against it.
 The force with which the shoe presses against the driven member is
the difference of the centrifugal force and the spring force.
 The increase of speed cause the shoe to press harder and enable
more torque to be transmitted.auto-ieti.blogspot.com

Centrifugal Clutch
Advantages
 This type of mechanical clutch
is automatic, so no kind of
control mechanism is necessary.
 Centrifugal clutch is fairly cheap
compare to normal type on
clutch.
 It prevents engine from stalling
in other words minimizes engine
braking force.
 It is very helpful in various
speed ranges compare to direct
drive system.
Disadvantages
 This clutch is not appropriate
for transferring significant
torque or power because they
can slip if loaded heavily.
 Sometimes the centrifugal
clutch do not engage or
disengage reliably and therefore
can cause a safety hazard.
 Some loss in hose power to rear
wheel due to friction pads or
shoes movement.

 One big problem occur in centrifugal clutch is that they work
sufficient enough at higher speeds but at lower speed they
don’t do their work sufficiently.
 So the need of another type of clutch occurs, which can work
at higher speed as well as at lower speed. This type of clutch is
known as semi-centrifugal clutch.
 This type of clutch uses centrifugal force as well as spring
force for keeping it in engaged position.
 The springs are designed to transmit the torque at normal
speed, while the centrifugal force assists in torque
transmission at higher speeds.

Free Wheel Clutch
 A freewheel or overrunning clutch is a device in a
transmission that disengages the driveshaft from the
driven shaft when the driven shaft rotates faster than
the driveshaft.
 An overdrive is sometimes mistakenly called a
freewheel.
 The condition of a driven shaft spinning faster than its
driveshaft exists in most bicycles when the rider holds
his or her feet still, no longer pushing the pedals. In a
fixed-gear bicycle, without a freewheel, the rear
wheel would drive the pedals around.auto-ieti.blogspot.com

Free Wheel Clutch

Free Wheel Clutch (Advantages)
 Engine power is not required while vehicle is moving down the
slop and accelerator pedal is not pressed.
 Due o free wheel other transmission units are disconnected
from the engine & gear box and starts rotating freely.
 When the wheels start rotating faster, then free wheel clutch
prevent the power of engine supplied to them, hence fuel is
saved.
 The friction of engine and gear box doesn't resist the operation
during free wheeling.
 By using this device we can easily shift the gear.
 This device rotates the wheel freely and also not resisting the
vehicle moving in forward direction.auto-ieti.blogspot.com

Free Wheel Clutch (Disadvantages)
 The construction of vehicle is become complex by using this
device.
 The additional time and cost for repair & maintenance is
required.
 Automatic or hand operated device is needed to prevent the
working of free wheel clutch.
 This clutch is to be locked for driving car in reverse gear and
climbing the sloppy road.
 The braking is to be done, when the engine & gear box are not
in connection with other transmission units due to free wheel
clutch.

Clutch Actuating Mechanism
 The clutch operating mechanism transfers the force exerted by
the driver at the clutch pedal to the clutch and either engages
or disengages the clutch.
 Clutch actuation mechanism can be classified as :
1. Mechanical Clutch - Where the driver’s foot effort is
transmitted to the clutch through a set of levers and links
2. Cable Clutch - Where the driver’s foot effort is transmitted to
the clutch through a cable.
3. Hydraulic Clutch - Where the driver’s foot effort is
transferred to a hydraulic oil medium, which in turn operates
the clutch through master cylinder & slave cylinder. Pedal
efforts are lower & doesn't require clutch pedal free play
adjustments.

Mechanical Mechanism(Rod Operated)

 The clutch operating mechanism connecting to the engine is enclosed in the
clutch bell-housing and uses a cross-shaft.
 A fork-arm, which supports a thrust bearing and saddle, is clamped to the
cross-shaft.
 One end of the cross-shaft extends outside the bell-housing and a
withdrawal lever is attached to it.
 This lever is connected to the foot-pedal either directly by means of the
withdrawal rod for the chassis-mounted foot-pedal or by a relay lever to
transfer the horizontal withdrawal movement into a vertical one for the
bulkhead pedal layout.
 As the clutch driven-plate wears the adjustment in both the layouts is
carried out either by a screw-nut or by a turnbuckle.
 A pedal adjustment stop is provided with both linkages, for positioning the
pedal suiting to the driver’s foot and, in the case of the chassis-mounted
pedal, clears the floorboards.

 As the clutch pedal is pressed, it pivots about the mounting
bracket and the withdrawal rod pulls back or forwards according
to the arrangement.
 Consequently the withdrawal lever rotates the fork-arm about the
cross-shaft and pushes the thrust-bearing saddle against the
clutch release-plate.
 This causes the movement of the release levers towards the
flywheel, so that they pivot about the eyebolt pins, withdrawing
the pressure-plate from the driven-plate thereby interrupting the
drive.

Cable Operated Mechanism

Cable Operated Mechanism
 The cable assembly uses an inner multi-strand steel-wire core
and an outer cable sheath of a spiral wound flexible sleeve
normally with nylon end-pieces.
 This plastic sleeve provides very good rubbing wear properties
without requiring in general any lubrication.
 The cable is run between the clutch bell-housing and the car
bulkhead, where the pedal is normally located.
 A screw adjustment is incorporated at either the pedal or the
bell-housing end to alter the length of the outer cable sleeve,
for increasing or decreasing the free-play of the inner cable.

Hydraulic Operated Mechanism

 A master-cylinder, mounted on the bulkhead and a push-
rod joining the clutch-pedal to the sliding piston, provides
the control of the clutch action.
 A slave cylinder unit containing the piston, is installed on
an extension formed on the bell-housing flange.
 The slave piston relays the slightest movement to the
fork-lever through the slave pushrod.
 The thrust bearing assembly is fixed to one end of the fork
lever, and a spherical pivot is installed slightly in from this
end.

 The master-cylinder piston pushes a continuous column of fluid
through the pipeline when the clutch pedal is pressed down.
 This causes the displacement of an equal volume of fluid into the
slave-cylinder due to which the piston moves out and tilts the fork
lever.
 This causes the thrust bearing to defect the release-fingers so that
the driven-plate is slipped.
 When the pedal is released, engagement of the clutch occurs due
to which the fluid returns to the master-cylinder and its reservoir.
 The return-spring in the slave-cylinder then maintains a slight
pressure on the fork-lever for a continuous contact of the thrust
bearing with the release-fingers.auto-ieti.blogspot.com

Fluid Coupling
 A fluid coupling or hydraulic coupling is a hydrodynamic
device used to transmit rotating mechanical power.
 It has been used in automobile transmissions as an alternative
to a mechanical clutch.
 It has widespread application in marine and industrial machine
drives, where variable speed operation and controlled start-up
without shock loading of the power transmission system is
essential.

Fluid Coupling

Advantages of Fluid Coupling
 It provides acceleration pedal control to effect automatic
disengagement of drive to gearbox at a predetermined
speed.
 Vibrations from engine side are not transmitted to wheels
and similarly shock loads from transmission side will not be
transmitted to engine.
 The engine will not stall if it is overloaded.
 No wear on moving parts and no adjustments to be made.
 No jerk on transmission when gear engages.

Advantages of Fluid Coupling
 Vehicle can be stopped in gear and move off by pressing
acceleration only.
 There is no direct firm connection between engines and
wheels. So when engine is overloaded, it will not stop. But it
results in slip within coupling.
 Unlike friction clutch, slip within coupling does not cause
damage within working components.
 In case of FC, engine is not forced to operate at very low
speeds when it is overloaded.
 No wear is experienced on impeller or turbine blades.

Clutch

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à Clutch

Similaire à Clutch (20)

Dernier

Dernier (20)

Clutch