Antiskid device for pressure-medium operated brakes

Claim 1

In an antiskid device for pressure-medium operating brakes in a vehicle, the combination of an antiskid valve connected between a brake control line and a brake cylinder line and having a braking position and a skidding Position, said antiskid valve having a first chamber and connected to a pressure relief line, means in said antiskid valve for establishing a passage therein between said brake control and brake cylinder lines in the braking position and for establishing a passage between said brake cylinder line and the atmosphere in the skidding position, said antiskid valve has a differential pressure piston the larger surface of which is directed toward said first chamber and the smaller surface area being continuously connected to a source of pressure-medium, a check valve defining a throttle passage in said piston connecting the smaller surface to said larger surface thereof, valve means responsive to skidding for connecting said first chamber to said pressure relief line when skidding occurs and having means for connecting said first chamber to a source of pressure-medium in the braking position, a normally open monitor valve connected in said pressure relief line, means for closing said monitor valve in response to a delay in the return of the antiskid valve to the braking position exceeding that of a skidding action, and means including a throttle restriction bypassing said skid responsive valve means for supplying pressure-medium to said first chamber so that the antiskid valve is returned to the braking position when the skid responsive valve means continues to connect the antiskid valve first control chamber to the pressure relief line for a time in excess of a skidding action, said monitor valve has a second chamber connected to said first chamber through said throttle restriction, said monitor valve comprises a cylinder having a moveable piston therein defining a second chamber on its larger surface and a spring chamber on its smaller surface, a spring within said spring chamber acting upon said piston to close the monitor valve, a valve member in said pressure relief line connected to said piston to open and close said line, means connecting said spring chamber to said pressure relief line upstream of said valve member, and a throttle passage bypassing said valve member.