an hydraulic anti - skid braking system for automobiles , comprising a master cylinder , a brake , a flow control valve , a solenoid valve , a piston pump , and an expander cylinder . during a skid condition , the solenoid valve is opened , and a the pump draws fluid from the brake through the solenoid valve and delivers fluid to the flow control valve to shut off a hydraulic connection between the master cylinder and the brake , while reducing fluid pressure to the brake . when pressure is equalized between the brake and the hydraulic line that is connected to the master cylinder , the control valve returns to its initial operation position .