Diaphragm clutch: Definition, Diagram, Working, Application, Disadvantages

Hello friends, Today we are going to learn about the Diaphragm Clutch, An kind of Automobile clutch. But before the start, let’s briefly understand an Automobile Clutch.

An automobile clutch is a device that ensures smooth engagement and disengagement between the power transmitting shafts i.e. driving shaft and the driven shaft.

The vehicle driver can easily shift gears or slow down the vehicle by pressing the clutch pedal. The pressing movement of the clutch pedal breaks the contact between the driving shaft and the driven shaft which results in the termination of power transmission from the engine to the gearbox.

What is a Diaphragm clutch?

A diaphragm clutch is one of the types of automobile clutch which uses the diaphragm spring for the engagement & disengagement of the clutch.

As compared to plate type clutch, In diaphragm clutch, the Diaphragm spring is used at place of the coil spring to keep axial force (Clamping force) on a pressure plate.

Working principle:

The diaphragm clutch works on the Friction principle.

Friction is responsible for the power (Torque) transmission from Flywheel to the Gearbox.

A Plate which having Friction lining on its surface is known as Friction Plate. The friction Plate is pressed onto the Flywheel under the axial force applied by a pressure plate.

In the Engaged Condition of the Clutch, Flywheel, Friction Plate & Pressure plate are united due to Axial Force exerted by a Pressure plate.


It consists of a friction plate/clutch plate, pressure plate, flywheel, diaphragm, release bearing, clutch pedal, and release fork.

1) Pressure Plate: This plate is used in the clutch to force the friction plate onto the flywheel. The diaphragm spring is located on one side of the pressure plate.

2) Flywheel: Flywheel is connected to the vehicle engine crankshaft and rotates with it. In the running condition of the vehicle, the pressure plate forces the friction plate onto the flywheel, Due to friction between the friction plate and flywheel, the power transmits from the flywheel to the output clutch shaft.

3) Diaphragm: Diaphragm is one of the types of springs which has a circular shape. It helps to keep the pressure on a friction plate. When the release bearing presses the inside part of the spring, the outside part of the spring moves outwards and presses the friction plate on the flywheel.

4) Friction Plate: This plate is generally located between the flywheel and pressure plate that has a friction material onto the surface of both sides. The friction material is responsible for power transmission when these plates are united during an engagement.

Diaphragm clutch

5) Release Fork: The release fork performs work to press the release bearing to press the Diaphragm spring. Release Fork is Connected to Clutch Pedal through Linkage.

6) Release Bearing: It is a bearing that is operated by the release fork to press the diaphragm spring.

7) Clutch Pedal: The clutch pedal is the pedal that is connected to the clutch and operated by the driver.

Diaphragm clutch working:

Let’s understand the working of the diaphragm clutch in two different positions with the help of diagrams.


Diaphragm clutch

1] When the driver presses the clutch pedal through a linkages release fork presses the release bearing.

2] Due to the release Fork presses the release bearing, Release Bearing presses the middle portion of the diaphragm to move inwards.

3] Due to the inwards movement of the middle portion of the diaphragm, the outside part of the diaphragm moves backward as well as pressure plate also moves backward.

4] Therefore due to the pressure plate’s backward movement, pressure on the friction plate gets removed. So there is no friction between the plates & flywheel. Hence no power transmission takes place.  Hence clutch gets Disengaged.


Diaphragm clutch

1] When the driver releases the clutch pedal, results in diaphragm again comes to its original position. 

2] Hence outside part of the diaphragm moves inside & presses the pressure plate on the friction plate & flywheel. Therefore friction occurs between them. Hence power/torque again starts to transmit from the flywheel to the clutch shaft.  Hence Clutch gets Engaged.

Working video:

Diaphragm clutch advantages and disadvantages:


  1. It is lighter in weight.
  2. It has a compact size.
  3. Diaphragm spring applies more force hence it has a higher torque transmission capacity.
  4. It has fewer rotating parts hence no problem of noisy working.
  5. It has dynamic balancing even at high speed.


  1. For heavy vehicles, the size of the clutch becomes higher for increasing friction surfaces.


The diaphragm clutch has the applications in following vehicles:-

  1. Maruri suzuki swift
  2. Tata safari Storme
  3. Ford Ecosport
  4. Nissan navara


  1. How does a Diaphragm clutch work?

    When driver press the clutch pedal, diaphragm moves backward, Therefore pressure on the flywheel and friction plate gets removed, Hence no power transmits, in such a way clutch disengages.

    When the driver releases the clutch pedal, the diaphragm is again pressed on the friction plate and flywheel, and eventually power transmission starts. So in such a way clutch engages.

  2. What are the advantages of a Diaphragm clutch?

    It has the advantage of light in weight as well as dynamic balancing even at high speed.

Read about other types of clutch:

Single plate clutchMultiplate Clutch
Cone clutchCentrifugal Clutch
Hydraulic ClutchVacuum Operated Clutch
Electromagnetic ClutchAutomobile Braking System & its Types 

Media credits:

Pratik is a Graduated Mechanical engineer. He enjoys sharing the engineering knowledge learned by him with people.

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