Clutch: Definition, Working Principle, Function, Types, Advantages, Disadvantages & Applications [Notes with PDF]

Human beings depend upon automobiles significantly regarding their daily transportation. Therefore, in automobiles, there are lots of development that happens to utilize the maximum performance of the automobile. Often times an Engine is termed as ‘The Heart’ of a vehicle.

In an automobile, the clutch is the part that makes or breaks the relationship between an engine and a gearbox, mainly the clutch is a member of a machine component that transmits the power from the engine to wheels of the vehicle through the gearbox.

The clutch consists of several parts like friction surface, diaphragm spring, coil spring, hub, etc.

Among several types of clutches, friction clutches are the mostly used clutches in the vehicle industry.

In the vehicle, the clutch paddle or clutch lever is pressed to change the gear with respect to varying the vehicle speed.

These types are elaborately described in the section of Types of Clutches, of this assessment.

Along with that, the working principle, advantages, and disadvantages are also briefly described in this assessment. However, materials with which a clutch is made are also included in this assessment.

So let’s start with the definition first,

Definition of a Clutch:

In terms of mechanical engineering, a clutch is that kind of device which used by engineers to engage as well as to disengage transmission of power from a driving shaft to a driven shaft.

In the mechanism of a clutch, the driving shaft is directly connected to an engine whereas the other one or the driven shaft provides the power output that is utilized by the user for working.

Often times clutches are used to limit the motion or amount of power transmission between two components.

A common example of a clutch is that it is used in automobiles for engaging as well as disengaging gearbox and the engine of the automobile.

Here is an animated video by Learn Engineering, shows how a clutch works in a unique way!

Working Principle of Clutch:

When two revolving friction surfaces are brought into contact and pressed, then they are united and start to revolve at the same speed due to the friction force between them.

This is the basic principle of a clutch. The friction between these two surfaces depends on the area of a surface, the pressure applied to them and the friction material between them.

The driving member of a clutch is the flywheel mounted on the engine crankshaft and the driven member is a pressure plate mounted on the transmission shaft.

Some friction plates, sometimes known as clutch plates are kept between these two members. This whole assembly is known as the clutch.

Function of the Clutch:

The Following Function of an Automobile Clutch:

  • It can be disengaged. This allows engine cranking and permits the engine to run without delivering power to the transmission.
  • While disengaging, it permits the driver to shift the transmission into various gear according to operating conditions.
  • While engaging, the clutch slips momentarily. this provides smooth engagement and lessens the shock on gears, shaft and other parts of an automobile.
  • While engaging, the clutch transmits the power to the wheel without slipping, in ideal condition.

Types of Clutches:

In mechanical engineering different types of clutches are present. Numerous types of clutches are used in multiple purposes by engineers, although every type has its own advantages and disadvantages that should be addressed by engineers in order to increase the mechanical efficiency of a component.

The working principle of different types of clutches is also different in nature that is why in this section of this assessment, different types of clutches are discussed briefly to provide a detailed view.

The different types of clutch are:

  • Friction Clutch
  • Single Plate Clutch
  • Multi Plate Clutch
  • Cone Clutch
  • Centrifugal Clutch
  • Semi-centrifugal Clutch
  • Diaphragm Clutch
  • Dog and Spline Clutch
  • Electromagnetic Clutch
  • Vacuum Clutches
  • Hydraulic clutch
  • Freewheel Clutch

Friction clutch: 

Nowadays, most of the cars are using a basic friction clutch that mainly has some normal components, which people may be heard before. A friction clutch can be used by engineers in engaging and disengaging transmission and flywheel.

It is operated through a mechanical cable or hydraulic cable that consists of a clutch plate, a pressure plate, and a release bearing.

Friction Clutch

It is categorized into two parts. These are as follows:

  • Single Plate Clutch and
  • Multi Plate Clutch

Single Plate Clutch:

Single plate clutch is mainly used in lightweight vehicles for transmitting torque from an engine to the input shaft. As per the name of this Clutch it just has a single Clutch plate. 

components of single plate clutch

Multiplate Clutch:

This type of clutch has multiple clutch plates that are used to transmit power from the shaft of an engine to the transmission shaft of the same vehicle.

It is divided into two subdivisions also, they are wet clutch and dry clutch. Here is a Cool Video on Wet and Dry clutch [External Link]!

A clutch when operates within an oil bath then it is called a wet clutch. On the other hand, a dry clutch operates without oil. 

Multiplate Clutch sectinal view

Working Principle of Friction Clutch:

In a car, disengagement occurs between engine and gearbox by applying force over the clutch thus the springs are compressed by the peddle and the pressure plate slide to backward.

After this situation, the clutch plate has become free between the flywheel and the pressure plate. Now the clutch can shift gears.

The principle of clutch helps to rotate the flywheel until the engine shaft does not stop rotation. A clutch disengages the gearbox and engine since it has been pressed by the driver.

Moreover, when the clutch plate is released by the driver then the pressure plate again comes into its origin and Clutch becomes engaged.

Single plate and multiple plates are working in the same principle although the difference is that a single plate clutch is used in lightweight cars whereas multiple plate clutch is used in heavy-duty cars. 

Cone Clutch:

The frictional surface is located in this type of clutches as a cone that is why it is named as a cone clutch.

Two surfaces transmit torque through utilizing the concept of friction. The engine shaft consists of a male and a female cone. It is categorized under two sections they are Internal and External cone clutch.

1. Cones: female cone (green), male cone (blue) 2. Shaft: the male cone is sliding on splines 3. Friction material: usually on the female cone, here on male cone 4. Spring: brings the male cone back after using clutch control 5. Clutch control: separating both cones by pressing 6. Rotating direction: both directions of the axis are possible

Advantages of Cone Clutch:

Here are a few advantages of Cone Clutch:

  • As compared to each other, the cone clutch is more efficient than a single plate clutch.
  • In the case of cone clutch the friction surface experience the potential of the normal force.

Disadvantages of Cone Clutch:

Although there are some disadvantages of cone clutch, and here are those:

  • Cone clutch oftentimes inefficient to disengage the clutch. 
  • This situation takes place when the angle is more than 20°. 
  • Small wear can produce due to huge axial movement. 

Centrifugal Clutch: 

For engaging clutches, Centrifugal clutch uses the concept of centrifugal force. It is operated automatically according to the speed of an engine. Thus, in a vehicle, any clutch paddle is not required for the movement of the clutch.

A driver can stop as well as can start an engine without downing or upping the gear. 

parts of centrifugal clutch

Working Principle of Centrifugal Clutch:

This clutch includes a weight that is pivoted in a specific location.  According to engine speed centrifugal force moving up the weight and it applies force on the bell crank. Due to this, the plate is pressed. 

After that, the plate presses spring, which is the spring that mainly used to press the clutch plate.

Now the clutch has become engaged. 

The clutch remains to disengage up to a lower RPM that is near about 500rpm.  Lastly, the weights’ movement is controlled by Stop (H). 

Advantages of Centrifugal Clutch:

These are the advantages of Centrifugal Clutch:

  • It is automatic. 
  • Low cost and also low maintenance cost. 
  • Less wear and tear. 
  • Greater control over speed. 

Disadvantages of Centrifugal Clutch:

Here are some disadvantages of Centrifugal Clutch:

  • Sometimes, engines suffer from slippage in lower RPM. 
  • It cannot be used in a high-speed engine. 
  • Peak speed depends on clutch size. 

Semi-Centrifugal Clutch:

For keeping in the engaged position, the semi-centrifugal clutch uses spring force along with the centrifugal force. Semi-Centrifugal Clutch is made of a Clutch plate, Friction lining, Levers, Pressure plate, Flywheel, and Clutch springs.

semi centrifugal clutch diagram

Working Principle of Semi-Centrifugal Clutch:

Clutch spring and levers fix upon the pressure plate equally. At a normal speed of an engine, the clutch is designed to send torque spring.

At a normal speed and low power transmission, there is no pressure on the pressure plate. Hence, a clutch remains engaged.

At a high speed and high-power transmission, there is exert pressure on the pressure plate and the clutch has become engaged. 

Less stiff springs of the clutches help to get rid of any strain for clutch operations. 

When the speed of the vehicle decreases or speed fell rapidly, there is no pressure on the pressure plate by levers.

Advantages of Semi-Centrifugal Clutch:

Advantages of Semi-Centrifugal Clutch are:

  • Less stiff springs of the clutches at low speed.
  • There is no stain for clutch operations.

Disadvantages of Semi-Centrifugal Clutch:

And Disadvantages of Semi-Centrifugal Clutch are:

  • At a normal speed of an engine, the clutch is designed to send torque spring.
  • Assists the torque transmission at the high-speed engine by Centrifugal force. 

Diaphragm Clutch:

For engaging clutches, this type of clutch generates pressure on the pressure plate. This clutch is made of a diaphragm on the conical spring. The crown or finger type spring is attached to the pressure plate.

diaphragm clutch diagram

Working Principle of Diaphragm Clutch:

For the Diaphragm Clutch, engine power is sent to flywheel from the crankshaft.

Flywheel consists of friction lining, and the clutch is connected with flywheel.

As the pressure is applied to the pressure plate of the clutch, due to which, the clutch plate is located behind the pressure plate.

The diaphragm clutch is conical in shape. The outside bearing goes to the flywheel after pressing the clutch pedal of the clutch.

The outside bearing presses the Diaphragm spring. So that pressure plate is pushed backward by the Diaphragm spring.

That pressure disengaged the clutch by removing the pressure on the plate.

The Diaphragm spring and pressure plate came back on the normal state after releasing the pressure from clutch peddles.

Advantages of Diaphragm Clutch:

Here are some advantages of Diaphragm Clutch:

  • In Diaphragm clutch, no need to release levers as the springs function as the levers.
  • The coil spring increases the pressure more than the heavy paddles. So that there was no need for heavy paddles.

Disadvantages of Diaphragm Clutch:

  • As the clutch is a cone, the springs become stiffer, which needs more force to disengage.
  • At the higher speed, the coil spring faces the distortion tendency in a transverse direction.

Dog and Spline Clutch:

Dog and Spline Clutch has two parts. One is Dog clutch and another is a Spline clutch.

The Spline is also termed as a Sliding sleeve. This clutch is used to connect a shaft with the gear or to lock together, the two shafts.

dog and spline clutch

Working Principle of Dog and Spline Clutch:

The Dog clutch consists of external teeth and the Spline clutch consists of the internal teeth.

The two clutches are designed to rotate with each other together at the same speed but they never slip from each other.

For engaging two shafts, they have to be connected. The sliding sleeve goes backwards from the splined shaft and makes no contact with each other and then the clutch will be disengaged.

Advantages of Dog and Spline Clutch:

  • Clutches do not slip from each other.
  • Dog and Spline clutch made a huge amount of torque.
  • No friction takes place as they locked together when rotates.

Disadvantages of Dog and Spline Clutch:

  • At a higher speed, it is difficult to engage or disengage the clutches.
  • For disengagement and engagement, some relative motion is required. 

Electromagnetic Clutch:

The electromagnetic clutch is made of things that are applied in electrical engineering.

Those are as follows:

Rotor: Rotor is the part that connects directly to the engine shaft and helps to rotate the engine shaft and the driving shaft continuously.

Winding: Winding is attached behind the Rotor. It does not rotate. It is connected with the high voltage DC supply which is converted into the electromagnet by winding.

Armature: Armature is attached at the front of the rotor. It is attached to the hub by bolts or rivets.

Hub: Hub is attached behind the Armature. It is attached with the driven shaft by the bolts and rotates with the shaft.

Friction Plate: Base on the transmission of the power friction plate insertion between rotor and armature is done.

Supply Unit: Supply unit consists of a battery, clutch switch, wire, etc.

electromagnetic clutch diagram

Working Principle of Electromagnetic Clutch:

High Voltage DC supply is supplied to the Winding from dynamo or battery.

Winding produces an electromagnetic field that allures the pressure plate and engages the clutch.

For disengaging, the supply should be disconnected.

For reliving the switch of the clutch gear lever is made, therefore the clutch is disengaged by changing the gear by driver holds.

The Clutch is not engaged when the output is low of the dynamo at the low speed.

There are three springs on the pressure plate to engage the clutch at the low speed also. 

Advantages of Electromagnetic Clutch:

  • The operating process is easy.
  • The remote direction is used to operate a clutch as it has no requirement of linkage.

Disadvantages of Electromagnetic Clutch:

  • High cost.
  • As the high temperature is not sustained by any electrical components, there must be a limitation on operating temperature.

Vacuum Clutches:

The vacuum clutch works through a vacuum. So, its name is Vacuum clutch.

It consists of such parts. Those are:

  • Switch
  • Non-return valve
  • Solenoid
  • Piston
  • Vacuum Reservoir
  • Vacuum Cylinder
  • Battery
  • Inlet and Outlet
vacuum clutch diagram

Working Principle of vacuum clutch:

There is an existing vacuum in engine manifold (Inlet) which operates the Vacuum clutch.

The engine manifold is attached through a valve which is non-returnable with the Vacuum reservoir.

The reservoir is attached through a valve which is solenoid-operated with the Vacuum cylinder.

There is a switch in gear lever.

The battery operates the solenoid.

The lever changes the gear when it is held by the driver and the operation of the switch is done.

The pressure increases in the inlet manifold when open the throttle. So that non-return valve is closed, manifold isolates the reservoir. There is a vacuum present all the time in a reservoir.

Advantages of vacuum clutch:

  • It is far cheaper than other clutches.
  • It allows minimum travel of the actuator.

Disadvantages of vacuum clutch:

  • It consists of multiple components.
  • Sometimes sluggishness is found by engineers in a machine.

Hydraulic clutch: 

The working principle of vacuum and the hydraulic clutch is almost the same.

Although the significant difference between those is that, the hydraulic clutch operates through the pressure of oil, on the other hand, a vacuum clutch operates through a vacuum.

mechanism of hydraulic clutch

Working principle of Hydraulic clutch: 

Oil is pumped to the accumulator from the reservoir through a pump by an engineer. The connection between the accumulator and cylinder takes place by a control valve.

The engine of the vehicle operates the pump. A switch controls the valve. Apart from that, a linkage mechanism is used by engineers to establish the connection between piston and clutch.

The driver of a vehicle presses the gear lever of the vehicle and opens the switch to the valve to enable the oil flow. Due to the pressure of oil, the piston of the vehicle starts moving forward and backward that leads the clutch is engaging and disengaging.

Advantages of Hydraulic clutch: 

  • It is far easier to push. 
  • Providence of an equivalent amount of fluid.

Disadvantages of Hydraulic clutch: 

  • Sometimes, due to the use of silicon type of fluids, leakage can take place.
  • It can impact on the seals. 

Freewheel Clutch: 

It is often called in different names such as overrunning, one way and spring clutch. The transmission power produced by these types of clutch mainly takes place in one direction.

Freewheel Clutch is mounted by engineers behind a gearbox of an engine. 

freewheel clutch diagram

Working principle of Freewheel clutch:

The hub of the aforementioned clutch rotates clockwise and then the roller rise up the cams.

This movement takes place due to wedging action. After this situation, the hub followed by the outer racer.

The racer rotates in the same direction and at the same speed as compared to the hub. Hub is connected with the main shaft and the outer race is connected with output shaft by an engineer. 

Advantages of freewheel clutch:

Freewheel can deliver a better fuel economy.
Less wear and tear than the manual clutch. 

Disadvantages of freewheel clutch: 

If engineers try to produce engine breaking then freewheel clutch subjected to more wear. 

Clutch Material: 

There are so many materials have been used for making the clutch plates.

In past asbestos was the materials which were used to make the clutch plates. These days the manufacturers use compound organic resin with the wire of copper facing and they use ceramic material as well.

In the application of heavy-duty hauling or racing, typically there were used ceramic materials.

Now in the modern world asbestos has been classified as unreliable and generally these clutches not common with the modern advanced clutches.

Semi-Metallic Materials:

This type of material contains 30% to 65% of steel, iron, and copper.

These clutches have high heat resistance and hard to break and those are durable enough. The plates are reliable but not that good for high-speed operation.

Organic Materials:

These are the most common type of material that we used the most.

These materials clutches are capable of all kinds of usage in a variety of vehicles such as size.

This material contains high copper content because of that it can transfer the heat effectively.

Ceramic Materials:

These types of clutches contain organic and inorganic materials at the same time which include glass, rubber, Kevlar and carbon materials.

In this clutch, the coefficient of the friction is relatively high which lies between 0.33 to 0.4. In most of the intense application, this type of clutch is used, like in trucks and racing cars.


A clutch is a significant component of an engine as it capable to not only transmit motion from one machine part to another but it also can disengage and engage the driven as well as driving member.

Therefore, the importance of using a Clutch worldwide is that a driver can control the speed of an engine. The speed of rotation must be controlled by a person to maintain a safe and secure environment.

In addition to this, according to the above assessment, it can be said that a clutch is a must-use thing to separate the engine and wheels of a car.

The engine of an automobile rotates all the time whereas the wheels do not rotate.

Hence, the development of a clutch is truly needed to allow transmission between wheel and engine.

Moreover, a brief description of the clutch and it is the working principle along with the disadvantages and advantages are very significant to understand the working principle of a clutch and its usefulness in daily life.

So this is all about Clutch, I hope you liked this article if you did then don’t forget to share this article with your friend circle.


Centrifugal Clutch
Single Plate Clutch
Hydraulic Clutch
Multi-Plate Clutch

References [External Links]:

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Anup Kumar Dey

A Mechanical Engineer with 19 years of working experience in various renowned MNCs.

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