US 4,154,326 AGranted

Combined power valve and flow divider

AssigneeLambert Brake Corporation

InventorPeter Wolf

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Abstract

A closed-center brake system and brake valve are disclosed. A closed-center variable displacement pressure compensated pump delivers fluid pressure to a valve inlet which carries a normally closed check valve. When a valve operating rod is partially withdrawn from the valve, the check valve opens to admit fluid to a valve chamber; fluid pressure and flow are directed from the chamber to ports leading to a vehicle left-hand brake and a vehicle right-hand brake. Should fluid pressure be lost in upstream portions of the system, further pulling action on the valve rod will collapse the chamber and manually deliver pressurized fluid to the brakes. Another brake valve outlet port, located just downstream of the inlet check valve, provides for delivery of pressure compensated fluid back to the pump to cause the pump to operate with desired characteristics. Yet another brake valve outlet port delivers fluid to another system element, such as a hydraulically operated vehicle differential, so as to lock left-hand and right-hand vehicle drive trains together to prevent relative rotation when either the left-hand brake, the right-hand brake, or both brakes are operated.

Claims15

Dependent claims

A brake valve for use with a closed-center brake system, the valve comprising a housing defining an elongated bore closed at one end by a fixed end wall, a bi-ended rod extending through the housing end wall and having a first end outside the housing and a second end inside the housing, an apertured piston slidably disposed within the bore, the piston aperture defining a flow space permitting fluid to flow through the apertured piston, the housing defining an exhaust port permitting fluid which has moved past the apertured piston to flow out of the valve, a reaction piston carried on the second end of said rod and radially extending to cover the annular piston flow space, and being adapted to move toward the annular piston so as to halt the flow of fluid through the annular piston and create a movable end wall, the movable end wall, fixed end wall and bore thus defining at least in part a collapsible chamber in the power valve, an inlet port also defined in the housing to provide a fluid path between a closed-center brake system pump and the valve chamber, normally closed first check valve means in the valve inlet port for prohibiting fluid flow into the chamber and through the valve, and check valve actuator means for actuating the check valve and permitting fluid flow into the valve when the valve rod is at least partially withdrawn from the valve and the reaction piston is drawn toward the annular piston.

A closed center brake system comprising in combination, a closed-center variable displacement pressure compensated pump having an inlet for receiving relatively unpressurized fluid, an outlet for discharging fluid pressurized to a given degree, an inlet for receiving pressure compensated fluid, and control means operated by the pressure compensated fluid for controlling the discharge of fluid pressure to a given degree, a brake valve having a housing defining an exhaust port, an inlet port for admitting fluid to the valve, a valve rod extending through the housing, normally closed first check valve means in the valve for selectively admitting fluid to the valve, and a check valve actuator means interconnecting the check valve and the valve rod for permitting fluid flow into the brake valve when the brake valve rod is partially withdrawn from the valve, and a pump pilot port fluid path leading from the valve to the pump for leading pressure compensated fluid out of the valve and to the pump inlet for receiving the pressure compensated fluid.

Dependencies are inferred from the claim text.