Clutch mechanism, notably for a motor vehicle

A Diaphragm clutch mechanism having a cover (1), a diaphragm (2) having broadened orifices (23) of rectangular shape with lateral edges and being mounted on the cover by pivoting means (4) pivotally fixing the diaphragm to the cover, a pressure plate (3) fixed to the cover (1) with respect to it by coupling means (8), in which the cover (1) has a base (11) carrying studs (41) belonging to the pivoting means (4), said studs having a foot (50, 150) for fixing the stud (41) to the base (11), an annular guide portion (90, 190) designed to cooperate with the lateral edges (25) of broadened orifices (23) of rectangular shape, which the diaphragm (2) has for passage of the studs (41), and a head (42, 142) profiled so as to offer a support to the peripheral part, in the form of a belleville washer (21), which the diaphragm (2) has, wherein said guide portion (90, 190) is cut to form two lateral edges (91, 191) overall in the form of flats designed to cooperate with the lateral edges (25) of the broadened orifices (23) of the diaphragm (2), said head (42, 142) has in its top part a rounded part (63) in the form of a pad for offering a support to the diaphragm (2), the top face (62, 162) of the head (42, 142) of the stud (41) is cut into at its area of connection with the rear face (61) of the said head.