Abstract: A method and an apparatus for controlling a braking system, the control unit of which controls the wheel brakes receiving reference variables for control purposes. If these reference variables are not available, the control unit produces, on the basis of a predefined braking force distribution between the front and rear axles and in the context of an emergency mode, reference variables which it sets at the wheel brakes.

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.