Improvements in control valve assemblies for hydraulic braking and steering systems

摘要

In a vehicle hydraulic braking system separate first and second brake-applying valves (6,7) can be operated independently or simultaneously to supply pressurised fluid to brakes on opposite sides of a vehicle. Each valve (6,7) consists of a main piston (10) and a floating secondary piston (11) working in a bore (9), a throttle (27) between the adjacent ends of the pistons, and a valve stem (16) which carries, at opposite ends, valve heads (18 and 1921) of inlet valves and exhaust valves respectively. The valve stem (16) of the first brake-applying valve (6) is guided through an apertured guide member (17) which provides communication at all times between a pressure space (14) and a first inlet port (34), whereas the valve stem (16) of the second valve (7) is guided through a seal (28) in a guide member (29) which provides a sealed wall between the pressure space (14) and a chamber (31). A pump (1) supplies fluid through the inlet port (34) of the first valve (6), the exhaust port (23) of the first valve (6) is connected to the inlet port (34) of the second valve (7), and the exhaust port (23) of the second valve (7) is connected to a reservoir (2) to provide an open-centre system.