Vehicular hydraulic brake system with anti-locking arrangement

A vehicular hydraulic brake system with an anti-locking arrangement, said system comprising a master cylinder for connection to and operation by a brake pedal, brake actuating members connected to said master cylinder for receiving pressure fluid from said master cylinder, first valve means between said master cylinder and said brake actuating members, said first valve means including normally open directional control valve means for connecting or disconnecting said brake actuating members to said master cylinder and further having a normally closed directional control valve means for selectively connecting said brake actuating members to an unpressurized reservoir when said normally open directional control valve means is closed, replenishing means for assuring availability of pressure fluid at the brake actuating members, said replenishing means including shut-off valve means between said master cylinder and said normally open directional control valve means, said shut-off valve means being operative with said normally open directional control valve so that said shut-off valve means is open or closed in correspondence with said normally open directional control valve means, and an auxiliary pressure source and second valve means connected to discharge fluid pressure between said shut-off valve means and said normally open directional control valve means for providing fluid pressure for assuring the availability of a fluid pressure reserve proportional to the pressure from the master cylinder, the auxiliary pressure source comprises an electromotively drivable pressure fluid pump and a pressure control valve connected downsteam thereof, said pressure control valve includes a valve member for controlling the pressure of the pump flow and which is acted upon by the master cylinder pressure.