Safety hydraulic brake system for automotive vehicles

A safety hydraulic brake system for automotive vehicles having at least one set of front wheels and one set of rear wheels and brake cylinders at each wheel, a control cylinder having a first outlet communicated with brake cylinders at said front wheels and a second outlet communicated with brake cylinders at said rear wheels, said control cylinder having an inlet communicated with hydraulic pressure developing means, said control cylinder including bore means communicated with said first and second outlets, first and second piston means in said bore means, first and second valve means in said bore means and operable to permit pressurization of said front and rear wheel brake cylinders upon actuation of said hydraulic pressure developing means, said first and second piston means being operable to effect closing of said first or second valve means upon actuation of said hydraulic pressure developing means and upon loss of pressure at said front or rear wheel cylinders, respectively, whereby to prevent loss of pressure at the other of said front and rear wheel cylinders, said first and second piston means each including a bypass valve means operable to permit hydraulic fluid to pass said piston means, said bypass valve means closing upon initial pressurization of said front and rear wheel brake cylinders, and upon fluid pressure release, said bypass valve means shifts initially to an open position and then to another closed position while said first and second valve means shift to a closed position.