Abstract: A control valve for a vehicle fluid pressure braking system includes a housing having an inlet port, an outlet port and a delivery port. A plunger is movable in the housing to control communication between the ports. The plunger is provided with a shoulder which carries a sealing member which engages with a seating area on the housing to provide a seal controlling communication between the aforementioned ports. The seal includes a circumferentially extending cavity on the housing in which the body portion of the seal is received. A pair of beads project from the body portion of the seal in opposite axial directions, so that when the seal is moved into engagement with the seating surface, one of the beads sealingly engages the sealing surface, and the axial direction forces generated thereby force the bead on the opposite side of the seal into sealing engagement with a sealing surface on the plunger.

Abstract: A dual circuit brake valve includes a relay piston (50) having primary (82) and secondary (84) areas which are normally communicated to the pressure level at the primary outlet or delivery port (18). The relay piston (50) responds to a pressure differential across the relay piston to control communication to the secondary outlet or delivery port (22). A control mechanism (92) is responsive to a control signal to vent the secondary area (84) to thereby establish a differential area across the relay piston (50), so that the relay piston (50) will establish a pressure level at the secondary outlet or delivery port (22) which is a predetermined fraction of the pressure level at the primary outlet or delivery port (18).

Abstract: A braking system for a tractor-trailer combination vehicle having air brakes includes a two plunger control valve in which one of the plungers controls the brakes on the tractor and the other plunger controls the brakes on the trailer. However, the valve is designed such that actuation of the plunger controlling the brakes on the tractor to a condition effecting an application of the spring brakes on the tractor automatically actuates the other plunger to effect an automatic actuation of the spring brakes on the trailer. Operation of the plunger controlling the trailer brakes is independent of the plunger controlling the tractor brakes, so that application of the trailer spring brakes may be effected without applying the tractor spring brakes. The tractor spring brakes may be released with the trailer brakes applied to permit bobtail tractor operation or permit the trailer to be parked with the tractor spring brakes released.

Abstract: A modular control valve manifold assembly is designed for installation in the dashboard of a vehicle equipped with air brakes. The manifold houses the valving required to control the air brake system, and includes a base which provides a plurality of bosses which extend from the base. Each of the bosses house a control valve assembly which controls communication to the vehicle air brake system. The valve assemblies are retained in their bosses by a removable retaining ring, so that the valve assemblies may be easily removed from the manifold through the front of the dashboard for servicing. Furthermore, although the manifold may house an indefinite number of valves, only a single inlet and a single exhaust are required. Each of the valve assemblies controls communication between the inlet, the exhaust, and one of several corresponding outlet ports.

Abstract: The service and emergency braking system for use on articulated vehicles having service brakes actuated by air pressure and having emergency brakes held in a released condition by air pressure. The system includes valving which is responsive to a pressure differential between the fluid pressure level in the service line connecting the portions of the articulated vehicle and a reference pressure, so that the emergency brake control is vented during a service brake actuation to permit the emergency brakes to effect a brake application when the pressure of the service line drops below the reference pressure by a predetermined amount, thereby providing braking on all portions of the vehicle in an emergency braking situation when the service brake line interconnecting the portions of the vehicle has been broken or has been left disconnected.