initial condition before each actual measurement application_number US 52424805 A description first of all reference is made to fig1 fig1 shows a typical electrohydraulic braking system of the following design a tandem type master brake cylinder comprises two brake circuits one of which is illustrated and the illustrated primary brake circuit 2 is connected to a pedal travel simulator 3 further a pressure fluid reservoir 4 is connected to the master brake cylinder 1 pumps 5 driven by a motor and a high pressure accumulator e g a metal pleated bellows accumulator 6 form a pressure fluid supply system being supplied with pressure fluid brake fluid out of the pressure fluid reservoir 4 the wheel brakes 7 of the rear axle are connected to this pressure fluid supply system by way of each one inlet valve 8 and as a result provide a controlled brake circuit 2 u2032 in addition a connection to the pressure fluid reservoir 4 can be established by way of one outlet valve 9 each the inlet and the outlet valves 8 9 are normally closed pressure increase in the wheel brakes 7 occurs by opening the respective inlet valve 8 while pressure decrease occurs by opening the respective outlet valve 9 a controlled brake circuit 2 u2032 is provided this way and the pressure delivered to the wheel brakes 7 is determined by the master brake cylinder pressure while the master brake cylinder 1.