What Is Clutch? – Function, Types, Working, Parts, Diagram

Learn everything you need to know about What Is Clutch? – from the types of clutches to how they work and how to choose the right one for your vehicle. Get expert advice and tips on maintaining and repairing clutches.

What Is Clutch?

What Is Clutch
What Is Clutch?

It is the most important part of the engine in an automobile. A clutch uses to transfer rotating motion or torque from one shaft to another shaft when requires. The torque developed by the engine at the initial speed is very low. Therefore it is impossible to start the engine under load.

Hence a device that use to engage and disengage the engine from the transmission system is called a clutch. It permits the gradual taking of load when adequately operated, thereby it prevents jerky motion of the vehicle, and this avoids undue strain on the parts of the vehicle as well as passengers.

Necessity Of Clutch

It is a device that is necessary to transmit power from the engine to the wheels of the vehicle by engaging the engine to the transmission system gradually without giving the jerks to the body of the vehicle.

Function Of Clutch In Car

Working Of Clutch
Working Of Clutch

As soon as the contact is made, they are united due to friction between them and the flange D starts rotating with flange C. The rotational speed of flange D depends on the friction between surfaces C and D which in turn is proportional to the external force applied.

If the force gradually increases, the speed force transmitted will also increase gradually. The torque transmitted by the friction clutch depends on the pressure applied on the flange, coefficient of friction of the surface materials, and the radius of the flange. By increasing any of them, the force transmitted can increases.

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Working Of Clutch

It is is defined as a system that is used to connect or disconnect the engine from the rest of the transmission elements. It is located between the engine and gearbox. During normal running and stationary position, it is always in the engaged condition.

It is disengages when the driver processes the clutch pedal. It disengages for starting, changing gears, stopping, and idling. When the clutch engages, the engine will connect to the transmission, and power flows from the engine to rear wheels through a transmission system When the clutch disengages by pressing the clutch-pedal, the engine will disengage from the transmission. Thus, the power does not flow to rear wheels while the engine is still running.

It works on the principle of friction. In Figure, the driving shaft A with flange C is rotating at ‘N’ rpm, and shaft B with the flange D is keyed to the driven shaft which is in a stationary position when the clutch is not engaged. Now, an external force is applied to the flange D so that it comes in contact with flange C.

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Principle Of Clutch

  1. To allow the engagement or disengagement of gear when the vehicle is stationary and the engine is running.
  2. To transmit the engine power to rear wheels smoothly without shocks to the transmission system when the vehicle is in motion.
  3. To permit the engaging of the gears when the vehicle is in motion without damaging gear wheels.

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Application Of Clutch

  1. Automobile Use – Heavy vehicles, four-wheelers such as cars, trucks, buses, Two-wheelers, mopeds, scooters, and bikes.
  2. Industrial Use – Metal stamping, Pressworking, Packing machines, Indexing tables, Assembling machines, Printing machines, Conveyor belts, Pumps, Gear drives.

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Requirements Of Clutch

  1. It should be able to engage gradually and positively without the occurrence of sudden jerks.
  2. It should be capable of transmitting maximum torque to the engine.
  3. The design of the clutch is such that it should ensure the dissipation of heat sufficiently which is generated during operation.
  4. It should dynamically balance to the vibration in the transmission system. It is a very important requirement in modern cars which operate at high speed.
  5. The size of the clutch should be as small as possible so that it will occupy minimum space.
  6. A suitable mechanism should incorporate within the clutch for damping of vibration and elimination of noise produces during the transmission.
  7. To reduce effective clamping load on the car thrust bearing as well as wear on it, a provision should be made for clutch-free pedal play.
  8. It must have the non-tiresome operation of disengagement for the driver for higher power transmission.

Parts Of Clutch

Parts Of Clutch
Parts Of Clutch

1. Flywheel

The flywheel is an integral part of the engine, which also use as a part of the clutch. It is a driving member and connects to the pressure plate of the clutch shaft is houses with bearings in a flywheel. The flywheel rotates as the engine crankshaft rotates.

2. Pilot Bearing

The pilot bearing or bushing press into the end of the crankshaft to support the end of the transmission input shaft. The pilot bearing prevents the transmission shaft and clutch disc from wobbling up and down when the clutch released. It also assists the input shaft center of the disc on the flywheel.

3. Disc Plate

It is the driven member of the single-plate clutch and line with friction material on both surfaces. It has a central hub with internal splines to limit the axial travel along the splined gearbox driving shaft. This helps to provide damping actions against torsional vibrations or variations of the driving torque between engine and transmission.

A disc Plate is a plate between flywheel and friction or pressure plate. It has a series of facings inverters on each side to enlarge the friction. These clutch facings are made of asbestos material. They are highly worn and heat resistant.

4. Pressure plate

The pressure plate is made of special cast iron. It is the heaviest part of the clutch assembly. The main function of the pressure plate is to establish even contact with the driven plate facing through which the pressure springs can exert a sufficient force to transmit the full torque of the engine.

The pressure plate presses the clutch plate on to the flywheel from its machined surface. Between the pressure plate and clutch cover assembly, pressure springs are fits. The pressure will be withdrawn from the flywheel whenever release levers depress by the toggle or release levers pivots accordingly.

5. Clutch cover

The clutch cover assembly bolts to the flywheel. It consists of a pressure plate, release lever mechanism, clutch cover, and pressure springs. Generally, the clutch plate revolves with the flywheel. However, when the clutch has disengaged, the flywheel, as well as the pressure plates, are free to rotate independently from the driven plate and driving shaft.

6. Release levers

These pivots on pins to the clutch cover, their outer ends locate and positions on pressure plate legs, and the inner ends are projecting towards the clutch shaft. A careful and accurate adjustment of the release mechanism is one of the most important factors governing the performance of a clutch assembly.

7. Clutch shaft

It is a component of the gearbox. Since it is a splined shaft to the hub of the clutch plate, which is sliding on it. One end of the clutch shaft attaches to the crankshaft or flywheel and the other end connects to the gearbox or forms a part of the gearbox.

Types Of Clutch

1. Single Plate Clutch

What Is Single Plate Clutch
Single Plate Clutch

single plate clutch has one clutch plate. This clutch works on the principle of friction. It is the most common type of clutch used in motor vehicles. The clutch primarily consists of two members, one mounted on the driving shaft and the other on the driven shaft. These two shafts are parallel and concentric with each other; one shaft is fixed to its housing while the other is splined so that it can move axially. The driving torque can increase by increasing the effective radius of contact.

Application Of Single Plate Clutch

  • Single-plate clutches are commonly used in a wide range of applications, including automobiles, motorcycles, and industrial machinery.
  • They are simple and inexpensive to manufacture and capable of transmitting high levels of torque.
  • However, they tend to generate and wear more heat than other types of clutches and may require more frequent maintenance.

2. Multi Plate Clutch

What Is Multi Plate Clutch
Multi Plate Clutch

The multi plate clutch uses multiple clutch plates to make contact with the engine flywheel to transfer power between the engine shaft and the transmission shaft. A multi-plate clutch used in automobiles and machinery where high torque output is required. Multi plate clutches are used in heavy vehicles with racing cars and motorcycles for transmitting high torque. As compared to single plate clutches, these are smooth and easy to operate due to their assembly of friction surface’s contact. It may be used where the space is very limited.

Application Of Multi Plate Clutch

  1. Multi-plate clutches use where compact construction is required, e.g., scooters, motorcycles, and racing cars.
  2. The multi-plate clutch use in some heavy commercial vehicles to transmit high torque.

3. Cone Clutch

What Is Cone Clutch
Cone Clutch

The cone clutch is a type of friction clutch that has cone-shaped frictional areas. These types of clutches are commonly used in synchromesh and epicyclic gearboxes. It were the first to be used in automobiles and they continued to be popular, because of this simplicity, throughout the 1920s, when they gave way to single plate clutches, due to the poor working characteristics of the former.

Application Of Cone Clutch

  • It used in various manual transmissions as synchronisers.
  • They are used in various heavy machines as they can transmit high torque.
  • This Clutches are generally used in low peripheral speed applications.
  • It is commonly used in power racing boats.
  • This clutch are used in racing and rallying vehicles.
  • It is used in some automobiles and other combustion engine transmissions.

4. Centrifugal Clutch

What Is Centrifugal Clutch
Centrifugal Clutch

A centrifugal clutch is a type of clutch that uses centrifugal force to attach and remove the clutch. It consists of a set of weights that are attached to a rotating hub and a pressure plate. When the clutch is separated, the weight is held by a spring, allowing the hub and pressure plate to rotate freely. When the engine reaches a certain speed, the loads are thrown outward by centrifugal force, whereby they press against the pressure plate and attach the clutch.

Application Of Centrifugal Clutch

  1. This clutch is used in an automatic transmission system.
  2. It is used in scooters, mopeds, and go-karts.
  3. It is used in chainsaws, lawnmowers, textile industries, etc.

5. Semi Centrifugal Clutch

Semi Centrifugal Clutch Diagram
Semi Centrifugal Clutch

The Semi Centrifugal Clutch used in high-powered engines and racing car engines where clutch disengagements require appreciable and tiresome drivers’ effort. The power is transmitted partly by clutch springs and remaining by the centrifugal action of an extra weight provided in the system. The clutch springs transmit power at low engine speed and the centrifugal force transmit power at higher engine speed.

Applications Of Semi Centrifugal Clutch

  • Semi-centrifugal clutches are commonly used in applications where a smooth, gradual attachment is desired, such as in small engines, chain saws, and lawnmowers.
  • They are also used in some automotive applications, such as go-carts and mini-bikes.
  • The semi-centrifugal clutch is preferred in these applications because they provide a spontaneous, gradual attachment and do not require a separate disengagement mechanism.
  • They are also relatively simple and affordable to manufacture and maintain.

6. Hydraulic Clutch

What Is A Hydraulic Clutch?
Hydraulic Clutch

A hydraulic clutch is a type of clutch that uses hydraulic fluid to transfer force from the clutch pedal to the clutch mechanism. It consists of a master cylinder, activated by the clutch pedal, and a slave cylinder, which is attached to the clutch mechanism. When the clutch pedal is pressed, it pushes the hydraulic fluid from the master cylinder into the slave cylinder through a hose. The pressure of the fluid activates the slave cylinder, which in turn attaches or closes the clutch.

Applications of a Hydraulic clutch

  • The hydraulic clutch is preferred by reputable car manufacturers because they ensure quality and require less effort.
  • They are also used in heavy vehicles nowadays.
  • Hydraulic plates can be used in both single-plate and multi-plate clutches.
  • Self-adjustment and self-lubricating features are widely used for various applications in industries.

7. Diaphragm Clutch

What Is Diaphragm Clutch?
Diaphragm Clutch

A diaphragm clutch is a type of clutch that uses a flexible diaphragm spring to transmit torque between the engine and the transmission of a vehicle. It is a type of friction clutch, which means that it relies on the friction between two surfaces to transmit torque.

In a diaphragm clutch, the diaphragm spring is mounted between the pressure plate and the flywheel. When the clutch is engaged, the diaphragm spring is compressed, causing the pressure plate to clamp down on the flywheel. This creates friction between the flywheel and the pressure plate, transmitting torque from the engine to the transmission.

Application Of Diaphragm Clutch

Diaphragm clutches are commonly used in vehicles that require a smooth and gradual attachment, such as passenger cars and light trucks. They are also used in heavy vehicles such as buses and commercial trucks.

8. Positive Clutch

A positive clutch is used when a positive (no slip) drive is required. These clutches transmit power from the drive shaft to the powered shaft by interlocking the jaw or teeth. They are used much less than friction clutches.

The Jaw Clutch consists of two parts; One of them is permanently attached to the driver shaft. The other half is movable and connected to the operated shaft. It can slide axially onto the shaft independently, but cannot bend due to the key to the wing. They can transmit power in both directions; They are used when it is not necessary to attach or separate under load.

The spiral jaw clutch (Figure 2) is used when it only needs to transmit power in one direction; It can be left-handed or right-handed. They are used when it is necessary to engage and isolate while in motion.

Application of positive clutch

  1. Industrial Machinery – Positive clutches are used in a wide range of industrial machinery, such as conveyor belts, cranes and hoists, to transmit power and enable the circulation of heavy loads.
  2. Power Tools – Positive clutches are used in many power devices, such as drills, saws, and sanders, to transmit power and enable rotation of the tool’s bit or blade.
  3. Aerospace – Positive clutches are used in aircraft control systems to transmit power and enable the speed of flight control.
  4. Marine – Positive clutches are used in the propulsion system of ships and boats to transmit power from engines to propellers.
  5. Agricultural Machinery – Positive clutches are used in a variety of agricultural machinery, such as tractors and combine harvesters, to transmit power and enable the movement of equipment.

9. Vacuum Clutch

The vacuum clutch is the operating system that uses a vacuum for operation engagement and disruption of the clutch. The vacuum engine used for this operation is derived from the intake manifold. When a vacuum is created inside the intake manifold, it flows through the non-return valve and accumulates inside the vacuum reservoir.

When the driver shifts the gear, this system works automatically i.e. when the driver shifts the gear while driving the vehicle, the system turns on and separates the clutch. The advantage of using a vacuum clutch is that the clutch requires less effort to operate.

10. Electromagnetic Clutch

Electromagnetic clutch works electrically but transmits torque mechanically. That’s why they were called electro-mechanical clutches. Over the years, EM became known as electromagnetic versus electro-mechanical, referring more to their actuation method versus physical operation. Since clutch began to become popular 60 years ago, the variety of applications and clutch designs has increased dramatically, but the basic operation remains the same today.


What Is Clutch?

It is the most important part of the engine in an automobile. It uses to transfer rotating motion or torque from one shaft to another shaft when requires. The torque developed by the engine at the initial speed is very low. Therefore it is impossible to start the engine under load.

How many types of clutches?

1. Single Plate Clutch
2. Multi-Plate Clutch
3. Cone Clutch
4. Centrifugal clutch
5. Semi-centrifugal clutch
6. Hydraulic clutch
7. Conical spring clutch or Diaphragm clutch
8. Positive clutch or Dog and Spline Clutch
9. Vacuum clutch
10. Electromagnetic clutch

Where is the clutch located?

It is located between the engine and gear box.

Dual clutch transmission advantages?

1. The dual clutch transmission (DCT) Provides smooth acceleration by preventing changes in torque or gear shifts.
2. It increases the efficiency and Fuel economy compared to another automatic shifting.
3. It can handle the high torque demands of high-performance cars.
4. Switches gears much faster than others.
5. In DCT, Drivers can tell computers when to take action with the help of paddles or gearshift even with automatic engagement and disengagement of the clutch.

What is a clutch plate?

The plate consists of a steel plate with a splined central hub. Annular friction facings are attached to the steel plate by rivets. It is the driving member of the clutch and is held between the flywheel and the pressure plate. It is mounted on the clutch-shaft by splines.

What are the parts of the clutch?

1. Flywheel
2. Pilot Bearing
3. Disc Plate/clutch plate
4. Pressure plate
5. Clutch cover
6. Release levers
7. Clutch shaft
8. Springs

What is the material for clutch facing?

1. Leather
2. Cork
3. Cotton fabric
4. Asbestos base materials
5. SW3-AF (non-asbestos)
6. HWK 200 (non-asbestos)
7. Raybestos and Ferodo
8. Nonasbestos clutch facing – These are made of man-made fibre yarns such as glass fibre, mixed with special rubber compound to improve frictional performance.


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