CLUTCH

@Autogurukul

1
 CLUTCH
A clutch is a mechanism which enables the rotary motion of one shaft
to be transmitted at will to second shaft ,whose axis is coincident with
that of first.
Clutch is located between engine and gear box.
When the clutch is engaged, the power flows from the engine to the
rear wheels through the transmission system and the vehicle moves .
When the clutch is disengaged ,the power is not transmitted to the
rear wheels and the vehicle stops, while the engine is still running

Clutch is to be disengaged during

a) Starting the engine,
b) Shifting the gears,
c) Idling the engine
Clutch is engaged only when the vehicle is to move and is kept
engaged when the vehicle is moving

@Autogurukul
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 Functions
To permit engagement or disengagement of a gear
when the vehicle is stationary and the engine is
running.

To transmit the engine power to the road wheels

smoothly without jerks to the
transmission system while setting the vehicle in
motion.

To permit the engaging of the gears when the

vehicle is in motion without damaging the gear
wheels
3
.
@Autogurukul
 Characteristics of a good clutch
It must be simple to operate the clutch.

Power must be transmitted smoothly.

Once clutch is engaged, it must transmit power without slipping.

It must disengage accurately and quickly.

It must have good heat radiation properties.

It must be well balanced during rotation.

It must have long trouble-free life.

It must be easy to inspect, adjust and repair.

@Autogurukul
 Requirements of clutch
Torque transmission
Gradual engagement
Heat dissipation
Dynamic balancing
Vibration damping
Size
Inertia
Clutch free pedal play
Ease of operation

5 @Autogurukul
Friction clutch is used onClutch Components
most automobiles / tractors with
manual transmission
It consists of three main parts namely:
Driving Members
Driven Members
Operating Members
Driving member
It is comprised of flywheel ,
pressure plate, pressure springs
and releasing levers
Flywheel is the foundation on
which the clutch assembly is
mounted
Clutch side is machined smoothly
to provide friction surface
Pressure plate is made of cast iron
and is of the same size as of the
clutch disc @Autogurukul
 Friction clutch is usedClutch
on mostComponents
automobiles / tractors with manual
transmission
Driven Member
It has a clutch disc/plate which is
gripped between the flywheel and
pressure plate by the action of
springs
It is constructed into two parts
Outer disc of high quality steel
which is covered with friction
material
Inner disc is reinforced and
splined hub which engages
with the clutch shaft
Clutch plates are perforated
for quick and effective
dissipation of heat generated
due to friction surfaces @Autogurukul
Friction clutch is usedClutch
on mostComponents
automobiles / tractors with manual
transmission

Operating Member
It consists of
• Foot pedal and linkage
• Release or throw out bearing
• Release levers and springs

@Autogurukul
 Clutch - Types
Friction clutches
The friction clutches work on the fact that friction is
caused when two rotating discs come into contact
with each other
Cone clutches
Single plate clutch (coil spring & diaphragm type)
Multi-plate clutch
Semi centrifugal clutch
Centrifugal clutch
Fluid Coupling
Fluid flywheel Works on the transfer of energy from
one rotor to the other by means of fluid pressure.

@Autogurukul
 Friction clutches - Principle
Let, W = axial load applied
μ =coefficient of friction
R = effective mean radius
of friction surface.
Then, T= μWR
T = torque transmitted
Torque transmitted by a friction clutch depends upon three factors
i.e., μ, Wand R.
That is by increasing any or all of the above factors would increase
the amount of torque which a clutch can transmit
Coefficient of friction, μ - depends upon the materials comprising
friction surfaces

@Autogurukul
 Friction clutches - Principle

Axial Pressure, W - The maximum value of W is limited to that which

a driver can exert without undue strain.
Effective Mean Radius of contact surfaces, R -
The value of R cannot be increased beyond a certain maximum
which depends upon the space available in the particular type of
vehicle.
@Autogurukul
 Cone Clutch

Advantage
The only advantage of the cone clutch is that the normal force
acting on the contact surfaces in this case is larger than the axial
force, as compared to the simple single plate clutch in which the
normal force acting on the contact surfaces is equal to the axial
force. @Autogurukul
 Cone Clutch

Disadvantages
This type of clutch is practically obsolete because of certain inherent
disadvantages:
If the angle of cone is made smaller than about 20° the male cone
tends to bind or join in the female cone and it becomes difficult to
disengage the clutch.
A small amount of wear on the cone surface results in a considerable
amount of the axial movement of the male cone which cannot be
tolerated. @Autogurukul
Single Plate Clutch - Coil Spring Type

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Single Plate Clutch - Coil Spring Type

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 Single Plate Clutch – Diaphragm Spring type

ADVANTAGES
It is more compact than other designs.
It is easier to balance rotationally and is less subjected to unwanted effects due
to centrifugal force at high rotational speeds.
It gives uniformly distributed pressure on pressure plate.
It needs no release levers.
@Autogurukul
 Single Plate Clutch – Diaphragm Spring type

Minimum effort is sufficient to disengage the clutch.

It provides minimum number of moving components and hence
minimum internal friction is experienced.
This is very commonly used in cars, light Lorries and mini trucks but is
not much used in heavy vehicles
@Autogurukul
 Multi Plate Clutch

Multi-plate clutches are preferred in vehicles:

If the torque to be transmitted is high.
Space available is limited

@Autogurukul
Semi Centrifugal Clutch

@Autogurukul
 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. @Autogurukul
 Centrifugal Clutch

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. @Autogurukul
 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.

@Autogurukul
 ADVANTAGES
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. @Autogurukul
ADVANTAGES
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. @Autogurukul
THANK YOU

@Autogurukul