Despite significant progress, such as the adoption of disc brakes by Jaguar and Citroën in the mid-1950s, braking remained a problem. Wheels locked, a car turns into a sledge out of control. The AntiBlockierSystem or ABS, delivered by Bosch from 1978, electronically regulates braking wheel by wheel. Rotation sensors inform the ABS control unit when a wheel is locked. The pressure is released for a fraction of a second on this single wheel and then immediately reapplied. Braking is thus exploited at the limit of blocking and the steering remains operational.