The clutch mechanism diaphragm spring (16) comprises an elastic annular part (30) for pressing the pressure plate into contact with a clutch disc. Several levers (31) extend radially inwards from the elastic part. Each lever comprises end faces (37,38) inclined relative to the elastic part to form a slot (32). This slot directs an air current into the clutch consequent to its rotation and that of the diaphragm spring.
