Vacuum brake force booster for a slip-controlled brake system

A vacuum brake force booster in combination with an automotive hydraulic brake system including a plurality of wheel cylinders for operating individual wheel brakes, a manually operable brake pedal able to be position in a rest position or an advanced position, means for applying hydraulic pressure to said wheel cylinders by advance of said brake pedal from said rest position including an axially movable push rod, said vacuum booster including a housing, a movable booster wall subdividing said housing into vacuum and booster chambers, said vacuum chamber connected to a vacuum source, means drivingly connecting said push rod and movable wall to enable a boosting force to be applied thereto;

• valve means having alternate conditions, in a first condition placing said vacuum and booster chambers in communication with each other to deactivate said booster, or in a second condition discontinuing said communication and venting said booster chamber to atmosphere to activate said booster, said valve means including a valve body having actuating and deactivating positions corresponding to said valve means alternate first and second conditions respectively;
• mounting means mounting said valve body to be drivingly connected to said brake pedal to be moved therewith between said deactivating position and said actuating position as said brake pedal is moved between said rest position and said advanced position, said mounting means including a pedal piston connected to move with said brake pedal and normally move with said valve body and said mounting means also including means allowing relative movement between said pedal piston and said valve body upon application of a predetermined force to said valve body to shift said valve body relative said pedal piston and said brake pedal, and operator means for controllably applying said predetermined force to said valve body to shift said valve body and change said valve condition from that caused by said brake pedal movement and enable control of said valve means independently from said brake pedal movement.