Device for transmitting torque between two rotatable shafts

A device for transmitting torque between two rotatable generally axially aligned shafts comprising a stationary housing (1), two rotatable shaft members (2, 3) supported by said housing, a number of alternate clutch discs (10, 11) connected respectively to the two shaft members and engageable to counteract differential rotational speed between the shaft members, at least one hydraulic clutch piston (12) to engage the clutch discs, and a hydraulic pump arrangement (15-24;

• 40-42;
• 50-53;
• 60, 63) driven by the speed differential between the two shaft members, a high-pressure side of the pump arrangement being connected to the at least one hydraulic clutch piston, the combination comprising at least one control piston (15;
• 40;
• 50;
• 60) for a first one of said shaft members (3) is contained in the hydraulic pump arrangement (15-24;
• 40-42;
• 50-53;
• 60, 63) for movement in the housing (1), and in contact with a corresponding at least one control member (17;
• 61), said at least one control member being rotatable together with one of the shaft members and pumping control means including a cam curve (20) rotatable with the other shaft member (2) arranged to contact said at least one control member in such a way that the at least one control member and thus the at least one control piston are imparted an oscillating movement with a frequency directly proportional to the rotational speed differential between the two shaft members.