Abstract

A friction clutch is of the type comprising a clutch cover for attachment to a flywheel, a pressure plate, a main spring assembly arranged to act between the cover and the pressure plate to provide a clamp load to urge the pressure plate towards the flywheel and thereby grip a driven plate between the friction surfaces of the pressure plate and flywheel, and a release mechanism for relieving the clamp load. The pressure plate is formed in two relatively adjustable components which can compensate for variations due to wear in the thickness of the driven plate and thereby maintain a constant clamping condition of the main spring. An adjuster mechanism incorporates relatively adjustable inter-engaging members of the two pressure plate components which maintain a constant inter-engaged state during release and re-engagement of the clutch while the clutch remains in the desired state of adjustement. A control member responsive to movement between the released and engaged conditions of the clutch is operative to effect an incremental adjustment of the inter-engaging members when said movement exceeds a predetermined distance.