Vehicular hydraulic brake system with anti-locking

Claim 1

An anti-locking hydraulic brake system for automotive vehicles having vehicle wheels and wheel brakes, said system comprising, in combination: a master cylinder having a piston slidably mounted therein; a plurality of pressure fluid lines respectively connecting each of said wheel brakes with said master cylinder; a plurality of normally open control valves respectively provided in each of said pressure fluid lines between said master cylinder and said wheel brakes; a pedal-actuated booster integrally formed with said master cylinder and having a pressure piston slidably mounted therein between a pressure chamber adjacent to the outer end of said booster and a housing chamber at the inner end of said booster adjacent to said master cylinder, said pressure piston being directly slidable on the interior walls of a booster chamber surrounding said pressure piston, said pressure piston of said booster being connected to said piston of said master cylinder and forming a one-piece member therewith and said pressure piston being stepped wherein the effective area of its end which faces said housing chamber is greater than the effective area of its other end; an auxiliary pressure source; an unpressurized supply reservoir; a first pressure control valve (7) connected between said pressure source and said supply reservoir and having a pressure control input connected to said pressure chamber; and, a second pressure control valve (40) connected between said pressure source and said housing chamber for selectively connecting said pressure source to said housing chamber in response to an imminent locking condition.