Hydraulic brake system

A hydraulic brake system for automotive vehicles having front and rear axles, with at least one load sensor sensing the load condition of the vehicle and with at least one sensor associated with each vehicle axle for the detection of a brake force parameter relating to braking operation, with the measured values sensed being supplied to an electric evaluation circuit (18) which during the braking operation permanently computes braking pressure values for the wheel brakes of the rear axle and delivers corresponding control signals to a braking pressure modulator, wherein said brake force sensor (14, 15, 21, 22) is associated with at least one wheel (12, 13, 19, 20) of each vehicle axle;

• wherein a master cylinder (5, 44) is used for the hydraulic pressure supply to the wheel brakes (1, 2) of the front axle and wherein a braking pressure modulator (31, 53, 54) is used for the hydraulic pressure supply to the wheel brakes (3, 4) of the rear axle, the brake circuits of the front and rear axles being hydraulically separated from each other;
• and
• wherein an auxiliary pressure source is connected at the braking pressure modulator (31, 53, 54), said auxiliary pressure source consisting of a pressure medium accumulator (27), and a pressure medium pump (25), which applies a hydraulic braking pressure to the wheel brakes of the rear axles in correspondence with the sensed brake force parameter, hydraulic braking pressure at the rear axles being independent of the hydraulic pressure applied to the wheel brakes of the front axle;
• wherein the pressure of the pressure medium accumulator (27) pressurizes a working chamber (37) of an auxiliary cylinder (34), with the working chamber (37) hydraulically communicating with the wheel brakes (3, 4) of the rear axle of the automotive vehicle;
• wherein the auxiliary cylinder (34) has a booster chamber (60) connectible with the pressure medium accumulator (27), and wherein an electromagnetic valve means (32, 33) is arranged between the pressure accumulator (27) and the booster chamber (60) and which is connected with the evaluation circuit (18).