Declutching device having an hydraulic actuator for snap-fitting on a clutch of the pull-off type

A declutching device for a clutch of the pull-off type, for snap-fitted coupling with such a clutch, the declutching device comprising an hydraulic actuator which itself comprises:

• a movable member;
• a fixed member mounting the said movable member for sliding movement of latter with respect to the said fixed member in piston and cylinder relationship with said fixed member, between an extended position and a retracted position of said movable member with respect to said fixed member;
• a preloading coil spring operatively interposed between said fixed and movable members for biassing said movable member permanently towards its said retracted position;
• and retaining means operatively interposed between said fixed and movable members for retaining said movable member in its said extended position, wherein said fixed and movable members include means engaging respective ends of said spring so as to index each said end angularly to the corresponding said member of the actuator, said retaining means comprising at least one lug fixed with respect to one of said fixed and movable members, and an angle element fixed with respect to the other said member of the actuator and cooperating with a respective said lug whereby to provide axial and circumferential abutment between said actuating members in a predetermined relative angular position of the latter, so as to put said spring under torsional prestress.