Antilocking control system for vehicles

In an antilocking control system for wheel brakes of a wheeled vehicle, comprising sensors for monitoring the rotational behavior of the wheels, an evaluation circuit which receives the signals from the sensors and whick generates control signals based on the signals from the sensors, and a pressure reduction unit which receives the control signals from the evaluation circuit and which in addition to a setting for pressure buildup has a setting for pressure reduction and a setting for keeping the pressure at least approximately constant, the evaluation circuit including switching means for, within a single control cycle, (a) emitting a control signal for causing pressure reduction upon the occurrence of a tendency to lock, (b) emitting a control signal for keeping the pressure constant upon a subsequent wheel acceleration of a certain value and (c) normally also emitting a control signal for keeping the pressure constant in the transition phase between the end of the generated control signal for reducing pressure and the beginning of the signal indicating wheel acceleration (U.sub.+b);

• the improvement wherein said evaluation circuit further includes;
• a monitoring circuit means for determining whether within a given period of time T1 after the end of the pressure reduction signal a wheel acceleration signal (U.sub.+b) occurs and, upon the absence of such a signal within said period of time T1, for effecting a change in the normal regulation operation by causing the pressure reduction in subsequent control cycles to be prolonged until the occurrence of an acceleration signal (U.sub.+b) (Special operation);
• and further switching means for resetting the system to normal operation if an acceleration signal (U.sub.+b) appears within a period of time T2 <
• T1 after the end of a subsequent pressure reduction signal.