Hydraulic and electric powered parking brake system

Control means (12) for a redundant hydraulic and electric parking brake system (10) of a vehicle, said control means (12) including an actuator assembly (24) for activating a fluid delivery system (14) to effect an application of a remotely located parking assembly (90) by a spring (94,96), said fluid delivery system (14) including pump means (50), reservoir means (52), valve means (60), hydraulic displacement means (70) and solenoid means (80), said actuator assembly (24) being connected with said fluid delivery system (14) to effect a fluid communication therebetween, said control means (12) including electrical means (100) which is connected with said actuator assembly (24), said fluid delivery system (14), said solenoid means (80), and at least one vehicle brake (18) of said vehicle, said pump means (50) and said reservoir means (52) supplying said parking assembly (90) with fluid pressure to hold said spring (94,96) in a released position, said control means (12) responding to an operator input applied to said actuator assembly (24) to activated said hydraulic displacement means (70) and said solenoid means (80) for operating said valve means (60) whereby fluid pressure present in the parking assembly (90) is released and said spring (94,96) is thereafter allowed to provide a force for applying said vehicle brake (18), said actuator assembly comprising:

• a housing having a bore therein for retaining a plunger (32), said bore being connected by a line (42) to said hydraulic displacement means (70) of said fluid delivery system (14);
• a cam member (28) connected to an input rod (26) and said plunger (32);
• a switch member (30) connected to said cam member (28) for supplying said electrical means (100) with an input corresponding to the position of said cam member (28) within said bore for activating said solenoid means (80);
• a piston (36) located in said bore and separated from said plunger (32) by a caged spring (34);
• a return spring (38) located in said bore and acting on said piston (36) for urging said plunger (32) into engagement with said cam member (28), said cam member (28) being displaced by said input rod (26) to provide said plunger (32) with a corresponding input force which overcomes said return spring (38) and moves said piston (36) within said bore to supply hydraulic fluid to move said hydraulic displacement means (70) and operate said valve means (60) and allow said spring (94,96) to provide said force to apply said vehicle brake (18), said caged spring (34) allowing said cam member (28) to independently move said plunger (32) if said piston (36) remains in a substantially fixed position within said bore such that an input from said electric means (100) activates said solenoid means (80) to independently operate said valve means (60) and allow said spring (94,96) to provide said force to apply said vehicle brake (18).