Abstract: A hydraulic vehicle brake system in which normal service brake operation can be carried out by using external hydraulic energy, and in the event of a lack of external hydraulic energy, auxiliary brake operation by muscle power is possible, with a hydraulic transmission that comes from a master cylinder that can be actuated by means of the brake pedal. The external hydraulic energy is stored, for example, in an accumulator with a gas buffer, which can lead to a gas content in the hydraulic fluid for the service brake operation. The system includes a dual-circuit master cylinder associated with those wheel brakes of a vehicle axle that make a higher contribution to the vehicle deceleration and at the same time, cylinder/piston devices are installed between these wheel brakes and their associated service brake valves for the purpose of preventing hydraulic fluid from getting into these wheel brakes from the external energy source.

Abstract: A method and a device for controlling a braking system of a motor vehicle in open loop, in which a driver's braking input is converted into setpoint wheel-brake pressures for the individual wheel brakes, and the wheel-brake pressure is adjusted to the setpoint wheel-brake pressure in view of the measured wheel-brake pressure. Various secondary braking operations are initiated as a function of the type of fault. In response to a serious fault such as failure of the electrical energy supply, of the pressure supply, or an electrical fault in the control unit of the braking system, the valve arrangements controlling the wheel-brake pressures are switched over into a currentless state, and in response to a fault in detecting the driver's braking input, only the valve arrangements allocated to the front axle are switched into a currentless state.

Abstract: A method and a device for determining a pressure variable, in particular in a braking system having a delivery pump. The differential pressure between a first line and a second line is determined using as a baseline a variable which represents a measure for the speed of the delivery pump.