Types Of Clutches

CLUTCHES
ROLL NO:- FD20ME007
NAME:- BHANDARGE_VISHNU_SHNAKAR
GOVERNMENT POLYTECHNIC MUMBAI.
MECHANICAL ENGINEERING BRANCH - 2020-21

CLUTCH
 In clutch one shaft is usually connected to an engine or another power unit
(driving member), while the other shaft (driven member) provides output
power for the work.
 The clutches used in a motor vehicle are almost very similar in construction and
operation. There are some differences in the details of the linkage as well as in
the pressure plate assemblies.
 In addition, some clutches for heavy-duty applications has a two friction plate
and an intermediate pressure plate. Some clutches are operated by hydraulic
means. The dry single-plate type of friction clutch is almost used in American
passenger cars.

WORKING PRINCIPLE OF CLUTCH
 The clutch works on the principles of friction, when two friction surfaces are
bought in contact with each other and pressed they are united due to the friction
between them. If one is revolved, the other will also revolve.

THERE ARE 9 TYPES OF CLUTCHES, FOLLOWING ARE THE
DIFFERENT TYPES OF CLUTCHES:
1)Friction clutch
i. Single plate clutch
ii. Multiplate clutch
iii. Cone clutch
2) Centrifugal Clutch
3) Semi-centrifugal clutch

4) Diaphragm clutch OR Conical spring clutch
5) Positive clutch
I. Dog Clutch
II. Spline Clutch
6) Hydraulic clutch

7) Electromagnetic clutch
8) Vacuum clutch
9) Overrunning clutch or freewheel unit

1) FRICTIONSL CLUTCH
i) Single plate clutch

1. FRICTION CLUTCH
i) Single plate clutch :
 Single plate clutches are one of the most
commonly used types of clutches used in most modern light vehicles.
The clutch helps to transmit torque from the engine to
the transmission input shaft. As the name states it has only one clutch
plate.
 It consists of a clutch plate, friction plate, pressure
plate, flywheel, bearings, clutch spring and nut-bolts arrangement.
 The single-plate clutch has only one plate which is attached on splines
of the clutch plate. Single plate clutch is one of the main components
of the clutch. The clutch plate is simply thin metallic disc which has
both side friction surfaces.

1. FRICTION CLUTCH
 The flywheel is attached on the engine crankshaft and rotates with
it. A pressure plate is bolted to flywheel through clutch spring,
which provides the axial force to keep the clutch engaged position,
and is free to slide on the clutch shaft when the clutch pedal is
operated.
 A friction plate which is fixed between the flywheel and pressure
plate. The friction lining is provided on both sides of the clutch
plate.

1. FRICTION CLUTCH
Working:
 In a vehicle, we operate the clutch by pressing the clutch to peddle
for disengagement of gears. Then springs get compressed and the pressure plate
moves backwards. Now the clutch plate becomes free between the pressure plate
and flywheel. Due to this now the clutch is getting disengaged and able to shift
the gear.

1. FRICTION CLUTCH
Working:
 This makes flywheel to rotate as long as the engine is running and the clutch shaft
speed reduces slowly and then it stops rotating. As long as the clutch peddle is
pressed, the clutch is said to be disengaged, otherwise, it remains engaged due to
the spring forces. After releasing the clutch pedal the pressure plate comes back
to its original position and clutch is again engaged.

1. FRICTION CLUTCH
ii) Multi plate clutch :

1. FRICTION CLUTCH
 They are pressed by coil springs and assembled in a drum. Each of the
alternate plates slides in grooves on the flywheel and the other slides
on splines on the pressure plate. Hence, each different plate has an
inner and outer spline.
 The working principle of multiple clutches is the same as the working
of the single-plate clutch. The clutch is operated by pressing the clutch
pedal. The multiple clutches are used in heavy commercial vehicles,
racing cars, and motorcycles for transmitting high torque.

1. CONE CLUTCH
 The multiple clutches have two characters dry and wet. If the clutch is
operated in an oil bath, it is known as a wet clutch. If the clutch is operated
dry without oil, it is known as a dry clutch. The wet clutches are commonly
used in connection with, or as a part of the automatic transmission.

1. FRICTION CLUTCH
iii) Cone clutch :

1. FRICTION CLUTCH
 The figure shows the diagram of a cone clutch. It consists of friction
surfaces in the form of cones. This clutch uses two conical surfaces to
transmit torque by friction. The engine shaft consists of a female cone
and a male cone. The male cone is mounted on the splined clutch
shaft to slide on it. It has a friction surface on the conical portion.
Due to the force of spring when the clutch is engaged the friction
surfaces of the male cone are in contact with the female cone.
When the clutch pedal is pressed, the male cone slides towards
the spring force and the clutch is disengaged.
iii) Cone clutch :

1. FRICTION CLUTCH
iii) Cone clutch :
The main advantage of using a cone clutch is that the
normal force acting on the friction surface is greater than
the axial force, as compared to the single-plate clutch.
That’s why the normal force acting on the friction surface
is equal to the axial force.

1. FRICTION CLUTCH
iii) Cone clutch :
The cone clutches are basically becoming old because of some
disadvantages.
1) Let’s consider the angle of the cone is made smaller than 20°,
the male cone tends to bind in the female cone and it becomes
difficult to disengage the clutch.
2) A small amount of wear on the cone surfaces has a
considerable amount of axial movement of male cones, for which
it will be difficult to allow it.

2) CENTRIFUGAL CLUTCH
 The below figure shows a centrifugal clutch. To keep the clutches in the
engaged position centrifugal clutch uses centrifugal force, instead of spring
force. In these types of clutches, the clutch is operated automatically
depending upon the engine speed. That’s why no clutch pedal is required
to operate the clutch.
 This made so easy for the driver to stop the vehicle in any gear without
stalling the engine. Similarly, you can start the vehicle in any gear by
pressing the accelerator pedal.

Working of Centrifugal clutch
 It consists of weights A pivoted at B.
 When the engine speed increases the weights fly off due to the centrifugal
force, operating the bell crank levels, which press the plate C.
 The movement of plate C presses the spring E, Which ultimately presses
the clutch plate D on the flywheel against the spring G.

Working of Centrifugal clutch
 This makes the clutch engaged.
 The spring G keeps the clutch disengaged at low speeds at about 500rpm.
 The stop H limits the movement of the weights due to the centrifugal.

3) SEMI – CENTRIFUGAL CLUTCH

 The semi-centrifugal clutch uses centrifugal force as well as
spring force for keeping it in the engaged position. The figure
shows a semi-centrifugal clutch. It consists of levers, clutch
springs, pressure plate, Friction lining, flywheel and clutch
plate.

Construction of semi-centrifugal clutch:
 A semi-centrifugal clutch has levers and clutch springs which are arranged equally
on the pressure plate. The springs of the clutch are designed to transmit the
torque at normal engine speed. While the centrifugal force helps in torque
transmission at higher engine speed.
 At normal engine speeds, when the power transmission is low, the springs
keep the clutch engaged, the weighted levers do not have any pressure on the
pressure plate.

At high engine speed when the power transmission is high, the weights
fly off and the levers also exert pressure on the plate, keeping the
clutch firmly engaged.
 This types of clutches consist of less stiff springs, so that the driver may not get
any strain while operating the clutch. When vehicle speed decreases the weights
fall and the lever does not apply any pressure on the pressure plate.

 Only the spring pressure is applied to the pressure plate which
is enough to keep the clutch engaged. An adjusting screw is
fitted at the end of the lever, by means of which the centrifugal
force on the pressure plate can be adjuste

4) DIAPHRAGM CLUTCH
 The diaphragm clutch consists of a diaphragm on conical spring which produces
pressure on the pressure plate for engaging the clutch. The spring may be finger
or crown type attached on the pressure plate.
 Tapered finger type spring is shown in the figure. In these types of clutches, the
engine power is transmitted from crankshaft to flywheel. The flywheel has
friction lining and it is connected to the clutch as shown in the figure. The
pressure plate is provided behind the clutch plate because the pressure plate
applies the pressure on the clutch plate.

4) DIAPHRAGM CLUTCH
 In diaphragm clutch, the diaphragm is a conical shape of the spring. When we
press the clutch pedal the outside bearing moves towards the flywheel pressing
the diaphragm spring which pushes the pressure plate backwards.
 By doing this the pressure on plate removes and the clutch will get disengaged.
When we release pressure on clutch peddle the pressure plate and diaphragm
spring will come back to its normal position and clutch will get engaged.

4) DIAPHRAGM CLUTCH
Advantages:
 This types of clutches have no release levers because the spring acts as a series of
levers.
 The driver does not need to apply such heavy pedal pressure to hold the clutch
disengaged as with the coil spring type in which the spring pressure increases
more when the pedal is depressed to disengage the clutch.

5) POSITIVE CLUTCH
 The positive clutches are used when positive (no slip) drives are required. These
clutches transmit power from the drive shaft to the driven shaft by the
interlocking of jaws or teeth. They are rarely used as compared to friction clutch.
Fig. 1 shows a jaw clutch; that is the simplest form of a positive clutch. Jaw
clutch consists of two halves; one of them permanently fastened to the
driver shaft. The other half is movable and is attached to the driven shaft. It
can freely slide axially on the shaft, but cannot turn due to feather key. They
can transmit power in both directions; they are used when it is not
necessary to engage or disengage under load.

5) POSITIVE CLUTCH
 Spiral jaw clutches (Fig. 2) are used when it needs to transmit power only in one
direction; it may be left handed or right handed. They are used when engaging
and disengaging while in motion is necessary.

5) POSITIVE CLUTCH
Dog and spline clutch
A dog is a type of clutch it is used to lock
two shafts together or to connect a gear
and a shaft. The two parts of the clutch
are one is dog clutch which has external
teeth and another one is a sliding sleeve
which has internal teeth.

5) POSITIVE CLUTCH
Dog and spline clutch
Both shafts are designed in such a way that one will rotate another one at the
same speed and will never slip. When the two shafts are connected then you can
say the clutch is engaged. To disengage the clutch, the sliding sleeve moves back on
the splined shaft to have no contact with the driving shaft.
The dog and splined clutch are mostly used in manual transmission vehicles to lock
different gears.

6) HYDRULIC CLUTCH
 The hydraulic clutch working operation is the same as the vacuum clutch. The
major difference between these two is that the hydraulic clutch is operated by oil
pressure whereas the vacuum clutch is operated by vacuum.
 The figure shows the mechanism of a hydraulic clutch. It has fewer parts than
other clutches. It consists of an accumulator, control valve, cylinder with piston,
pump and a reservoir.

6) HYDRULIC CLUTCH
Working of hydraulic clutch:
 The oil reservoir pumps the oil into the accumulator through a pump. The pump
is operated by the engine itself. The accumulator is connected to the cylinder
through the control valve. The controlled valve is controlled by a switch that is
attached to the gear lever. The piston is connected to the clutch by a linkage
mechanism.
 When the driver holds the gear lever to change the gears, the switch opens the
control valve allows the oil under pressure to the cylinder. Due to the oil
pressure, the piston moves forward and backwards this causes the clutch to get
disengaged.

6) HYDRULIC CLUTCH
 When the driver leaves the gear lever the switch is open which
closes the control valve and the clutch will be engaged.

7) ELECTROMAGNETIC CLUTCH
 This types of clutches are operated by electrically but the torque is transmitted
mechanically. This is why this type of clutch is known as electro-mechanical
clutches. Over the year, now its became an electromagnetic clutch.
 These clutches have no mechanical linkage to control their engagement that’s
why it provides fast and smooth operation. The electromagnetic clutches are
most suitable for a remote operation that means you can operate the clutch at
distance.

7) ELECTROMAGNETIC CLUTCH
 The clutch has flywheel consists of winding. The electricity is supplied by the
battery. When the electricity passes through winding it produces the
electromagnetic field which causes it to attract the pressure plate to get engaged.
When the electricity supply is cut off the clutch is disengaged.
 In this clutch system, the gear lever has a clutch release switch that means when
the driver operates the gear lever to change gears the switch is
operated cutting off the current supply to the winding which causes the clutch to
disengage.

8) VACUUM CLUTCH
 The figure shows the vacuum clutch mechanism. This type of clutches uses the
existing vacuum in the engine manifold to operate the clutch. The vacuum clutch
consists of a reservoir, non-return valve, vacuum cylinder with
piston, and solenoid valve.

8) VACUUM CLUTCH
Construction and working:
 As the figure shows the reservoir is connected to the inlet manifold through a
non-return valve. A vacuum cylinder is connected to a reservoir through a
solenoid-operated valve. The solenoid is operated from the battery and the
circuit has a switch which is attached on the gear lever. The switch is operated
when the driver changes the gear by holding the gear lever.

8) VACUUM CLUTCH
 Let’s see how it works. When the throttle is opened the pressure increases in the
inlet manifold due to this the valve of the non-return valve closes. It separates
the reservoir and manifold thus the vacuum exists all the time in the reservoir.
 In the normal operation, the solenoid valve rod is in the bottom position of the
valve as shown in the figure and the switch in the gear lever remains open. At this
stage, the atmospheric pressure acts on both the side of the piston of the
vacuum cylinder, because the vacuum cylinder is open to the atmosphere
through the vent.

8) VACUUM CLUTCH
When the driver changes the gear by holding gear lever the switch gets
closed. The solenoid energizes and pulls the valve up this connects one
side of the vacuum cylinder to the reservoir. This action opens the
passage between the vacuum cylinder and the reservoir. Due to the
difference in the pressure, the vacuum cylinder piston moves forward and
backwards.
This piston movement is transferred by a linkage to the clutch, causing it
to disengage. When the driver is not operating the gear lever, the switch
is open the clutch remains engaged due to the force of springs.

9) OVERRUNNING CLUTCH OR FREEWHEEL UNIT

 The freewheeling unit clutches also known as spring clutch, overrunning clutch, or one-
way clutch. It is the most important part of every overdrive. The transmission of power
is in one direction similar to bicycles. The freewheeling unit is often mounted behind
the gearbox.
 The power is transmitted from the main shaft to the output shaft from driving the
output shaft when the planetary gears are in overdrive. A flywheel unit has a hub and
an outer race. The hub has internal splines to connect it to the transmission main shaft.
 The outer surface of the hub contains 12 cams so designed to hold 12 rollers in a
cage between them and the outer race. The outer race is splined to the overdrive
outer shaft.

Working:
 When the hub is driven in the clockwise direction, as shown in the figure. The
roller rides up the cams, and by their wedging action, they force the outer race
to follow the hub. Thus the outer race moves in the same direction and at the
same speed as the hub.
 When the hub speed slows down, and the outer race is still moving faster than
the hub, the rollers move down the cams, releasing the outer race from the
hub. Thus the outer race moves independent of the hub and the unit acts as a
roller bearing.

 The transmission main shaft is connected to the hub and the output shaft is
connected to the outer race. Thus freewheel unit can transmit power only from
the main shaft to the output shaft.

Types Of Clutches

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