Abstract: An electrohydraulic clutch includes a bidirectional electric motor, a hydraulic circuit and a multiple plate friction clutch pack. The bidirectional electric motor drives a ball screw through a gear reduction assembly. An electric brake on the motor output may be energized to inhibit its rotation. Alternatively, an anti-back drive wrap-spring assembly may be utilized on the motor output. The ball screw output bi-directionally translates a master piston of the hydraulic circuit which in turn advances and retracts an annular slave piston disposed adjacent the friction clutch pack. Hence, actuation of the electric motor displaces hydraulic fluid and compresses or relaxes the friction clutch pack, thereby transferring or inhibiting torque.

Abstract: An electrohydraulic clutch includes a bi-directional electric motor, a hydraulic circuit and a multiple plate friction clutch pack. The bi-directional electric motor drives a ball screw through a gear reduction assembly. The ball screw output translates a master piston of the hydraulic circuit which in turn advances and retracts an annular sleeve piston disposed adjacent the friction clutch pack. Hence, actuation of the electric motor displaces hydraulic fluid and compresses or relaxes the friction clutch pack, thereby transferring or inhibiting torque.

Abstract: An electromagnetic clutch assembly having a solenoid activated ball ramp operator provides reduced power consumption and improved control. The electromagnetic clutch assembly includes a primary or pilot friction clutch pack and a secondary or main friction clutch pack. An annular solenoid coil cooperates with an annular operator or plunger. When the coil is energized, the annular plunger translates and compresses the primary or pilot friction clutch pack. Activation of the pilot clutch pack retards motion of one of the members of the ball ramp operator which, in turn, compresses a secondary or main friction clutch pack disposed across the input and output members.