Brake system for automotive vehicles

In a brake system for automotive vehicles, comprising a vacuum brake force booster operatively disposed between a brake pedal and a master brake cylinder, said booster including at least two working chambers separated from one another by a first membrane plate, one of said working chambers being located at the front of said booster and, through a master magnetic valve, being in communication with a vacuum source, the other of said working chambers being ventable through a control valve actuable by the brake pedal to generate a brake force proportional to a force on the brake pedal, brake circuits for applying pressure to wheel brake cylinders, said circuits being in communication with the master brake cylinder, sensors operatively associated with each wheel of the vehicle to be decelerated by said system for detecting the rotational behavior of the wheels to identify a brake locking condition, said sensors generate output signals, said output signals applied as input signals to a central electronic regulator, said electronic regulator generating, in response to the input signals, at least one switch-over signal, said switch-over signal applied to the master magnetic valve, said valve adapted to switch-over so that the working chamber connected to the vacuum source is connected with atmosphere and disconnected from the vacuum source;

• the improvement comprising an auxiliary membrane plate fixed to a guide sleeve, a guide nozzle at the rear of said housing slidably receiving said guide sleeve, a rearwardly facing stop ring mounted on said auxiliary membrane plate engageable with a sealing ring on said rear housing portion, said auxiliary membrane plate being disposed between said other working chamber and an additional working chamber which is in permanent communication with the vacuum source, a piston rod for receiving the brake pedal force, said piston rod supported on the guide sleeve by a spring package, said first membrane plate being movable in said booster in a manner freely displaceable away from the guide sleeve.