Anti-skid control system utilizing a pump circuit for producing a voltage dependent on frequency

Claim 1

An anti-skid control system for a vehicle having a wheel to be controlled, including a generator driven by the wheel so as to produce an a.c. output the frequenCy of which is proportional to the speed of the wheel, a pump circuit to which the output from the generator is applied, said pump circuit producing an output voltage dependent on frequency and comprising in combination a pair of d.c. supply lines, an input terminal for connection to the generator output voltage, a first capacitor across which the output voltage of the pump circuit is developed, a second capacitor connected to the input terminal, and first and second transistors coupling the capacitors and supply terminals whereby the first capacitor receives a charging pulse for each positive and each negative pulse at the input terminal, said control system further including a differentiating circuit to which the output from the pump circuit is applied, the output from the differentiating circuit having a magnitude which is dependent on the deceleration of the wheel, and means operable by the output from the differentiating circuit for releasing the brakes if the output from the differentiating circuit exceeds a predetermined value.