Abstract: A pump includes a cam member and an armature plate received on an input shaft rotatably supported with a differential housing of a clutch. The pump also includes a cylinder rod slidingly received in a chamber of a master cylinder to pressurize a hydraulic fluid. The cam member includes a ring and a back plate. The ring has an outer, preferably symmetrical, surface with a variable radius defining a ramped portion for outwardly driving the cylinder rod when the cam member is rotated either forward or backward with respect to the differential housing. A coil generates an electromagnetic field when activated drawing the cam member towards the armature plate such that contact forces causes the cam member to rotate with the armature plate. A roller disc is rotatably supported at one end of the cylinder rod for rolling contact between the cylinder rod and the cam surface of the cam member ring.