wheels has a tendency to block this condition is shown in fig5 in which the solid line curve p 3 shows the course of the rear wheel brake pressure in accordance with a feature of the invention a timing element 23 for example a monostable flip flop ff and an or gate can be provided connected to the drain portion o of rear wheel brake valve unit 9 the constant pressure maintenance phase of the brake pressure can thus be changed by first providing for a short drop in braking pressure corresponding to the time constant of the timing circuit 23 this is shown in fig5 in the broken line p 3 39 it should be noted that priority is provided from the instant of time at which control of the rear wheel brake starts at time t 1 a pressure decrease commanded by this priority has priority level before the constant brake pressure maintenance phase rather than terminating control of pressure at the rear wheels when the transverse acceleration signal disappears or upon start of control of braking pressure at the two front wheels additionally a further timing circuit formed for example by a monostable ff 19 can be provided which is set upon occurrence of an output signal from the and gate 17 and then by a timing interval determines the constant braking pressure phase for the inlet valve i of the rear wheel brake valve unit 9 the fragmentary detailed circuit.