The system has control valves between the master cylinder and the wheel brakes and a motor driven hydraulic pump to lower the wheel brake pressures to a control programme. The ABS control monitors the dynamics of the brake modulation ie. the relative periods for pressure reduction and subsequent pressure rise, and compares the master cylinder pressure with the applied pressure, to achieve optimum braking effect. The relative periods for pressure reduction and pressure rise are set to one value when the brake pressure differs from the master cylinder pressure by more than a set value, and are set to another value when the difference is less than a set value. The control ensures that the pressure reduction rate becomes less steep as braking proceeds.
