Brake control valve system for rail vehicle air brake, comprising an emergency brake piston (7) having a first piston chamber (9) loaded by the quick action chamber with a much greater volume than its second piston chamber (8) loaded by the brake line. The effective pressure surfaces of the service brake piston and emergency brake piston are substantially identical. The emergency brake piston controls a first quick action exhaust valve (15) for venting smaller amounts of quick action air per unit of time, as well as a valve device (14) containing a second quick action exhaust for venting larger amounts of quick action air. Valve device (14) is pneumatically connected to the control piston (19) of a high pressure/emergency exhaust valve system (16) which operates only upon emergency braking. Piston (19) contains a nozzle (22) through which pressure remaining in the quick action chamber (10) during emergency braking is evacuated in a predetermined time. Piston (19) controls a high pressure seated valve (17) for connecting an emergency air container (3) to the brake cylinder during emergency braking, and a brake line emergency exhaust seated valve (18) providing large cross-sectioned connection of the brake line to atmosphere during emergency braking.
