The invention concerns a clutch mechanism comprising a wear take-up device including a ring (100) with ramps (12) bearing an outer toothing (31) and set between the pressure plate (1) and support means (3) to constitute a pressure plate (1, 100) with varying thickness between its friction surface (11) and the support means (3) and comprising, a box including a worm screw co-operating with the toothing (31). The invention is characterised in that it comprises at least a brake strap (51) borne by the pressure plate (1) and co-operating with the ramp (32) ring (100) such that, in the event of axial vibrations or overtravel of the clutch means during declutching, the ramps (32) do not rotate and there is no wear take-up.