What is Diaphragm Clutch? Construction, Operation of diaphragm Clutch.


The figure shows a diaphragm clutch. It consists of a diaphragm on conical spring which produces pressure on the pressure plate for engaging the clutch.


The spring is either of tapered finger type or crown type and it is mounted on the pressure plate. Tapered finger type spring is shown in the figure When the clutch is engaged, the spring pivots on the rear pivot rings as it is held in the clutch cover so that its outer rings are contacts the pressure plate. In this conical position of the spring, the clutch plate remains gripped between the flywheel and the pressure plate.

Diaphragm Clutch
Diaphragm Clutches


When the clutch pedal is pressed, the throwout beating moves towards the flywheel, pressing the centre portion of the spring, which causes the rim to move backwards. This causes to remove the pressure on the pressure plate and then the clutch is disengaged. The pressure of the Diaphragm spring increases until a flat position is reached and then decreases as this position is passed.

Diaphragm clutch Pressure Plate.
Diaphragm clutch’s Pressure Plate.

The figure shows a cross-sectional view of the diaphragm clutch of a Maruti-800 car manufactured in India by M/s. Maruti Udyog Limited. It is a dry single disc type. The diaphragm spring is of tapering-finger type, which is a solid ring in the outer diameter, with a no of tapering fingers pointing inward. The disc, carrying six torsional coil springs, is slidably mounted on the transmission input shaft with a serration fit.

The clutch cover is mounted to the flywheel and carries the diaphragm spring in such a way that the peripheral edge part of the spring then pushes on the pressure plate against the flywheel. When the clutch release bearing is held back, this is the engaged position of the clutch.
By depressing the clutch pedal causing the release bearing to advance and then pushing on the tips of the tapered fingers of the diaphragm spring. When this happens, the diaphragm spring acts like the release levers of a conventional clutch, pulling the pressure plate away from the flywheel, thereby interrupting the flow of drive from flywheel through the clutch disc to the transmission input shaft.


  1. Diaphragm Clutches has some advantages over coil spring type clutches. The diaphragm Clutches needs no release levers, the spring acts as a series of levers.
  2. The driver doesn’t have to apply such heavy pedal pressure to maintain the clutch disengaged as with the coil spring type, diaphragm spring pressure increases further when the pedal is released to disengage the clutch.
  3. Torque transmitting ability is not highly affected by the engine load.


The Diaphragm Clutch is used in Maruti-800 car built by M/s. Maruti Udyog Limited.

To understand how Diaphragm Clutches work, watch the video below:

diaphragm clutch Spring
diaphragm clutch Spring

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Creative Blogger And Automobile Engineer.

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