Abstract: In a control valve assembly for a vehicle hydraulic braking system a differential piston works in a stepped bore in the housing of the valve and is exposed at its end of greater area to an inlet port and at its end of smaller area to a chamber in the valve, the inlet port communicating at all times with the chamber through a restricted passage in the piston, and the chamber communicating with a further chamber in which a valve is located at least when the valve is in a first position in which the inlet port is in communication through the chambers with an outlet port for connection to the wheel brake.

Abstract: In a master cylinder assembly a booster valve assembly is adapted to control two separate supplies of booster fluid, and each supply is capable of advancing a modulator piston independently to operate a master cylinder.

Abstract: In a pneumatically-operable actuator assembly for a vehicle hydraulic braking system a control valve assembly comprises a first valve responsive to a signal of deceleration for controlling communication between an inlet passage for connection to a supply of air under pressure and a modulator chamber through a supply chamber, and a second valve downstream of the first valve for controlling communication between the modulator chamber and an exhaust passage and responsive to pressure in the supply chamber, the first valve being substantially smaller than the second valve whereby the pressure in the modulator chamber can be reduced rapidly in response to a relatively small reduction in the pressure in the supply chamber.

Abstract: In a vehicle hydraulic braking system the supply of fluid from an hydraulic master cylinder to the slave cylinder of a wheel brake is controlled by an actuator assembly which includes a modulator assembly for controlling the supply to the slave cylinder in accordance with the deceleration of a wheel operated by the slave cylinder, and both the master cylinder and the actuator assembly are actuated in response to separate supplies of the same fluid pressure medium.

Abstract: A booster operated master cylinder piston for use in an anti-skid braking system includes a modulator piston located between the master cylinder piston and the booster valve assembly. In the event of a skid the pressure of booster fluid acting on the modulator piston is equalized across the modulator piston.

Abstract: A master cylinder assembly for a vehicle hydraulic braking system comprises a pedal-operated valve assembly for controlling a supply of fluid under pressure to a power chamber in a housing on the opposite side of a piston to a pressure space which has an outlet for connection to a wheel brake, and a second piston is adapted to be applied by the pedal to generate fluid pressure in said pressure space.

Abstract: A booster operated master cylinder piston for use in an anti-skid braking system includes a modulator piston located between the master cylinder piston and the booster valve assembly. In the event of a skid the pressure of booster fluid acting on the modulator piston is relieved.

Abstract: An actuator assembly for a vehicle brake includes three axially aligned pistons, a first actuating piston for applying the brake hydraulically during normal service braking; a modulator piston movable for anti-skid purposes between a first position in which an inlet valve controlling the supply of fluid to the first actuating piston is open, and a second position in which the inlet valve is closed; and a second actuating piston resiliently urged through the modulator piston to engage the first actuating piston to apply the brake for parking purposes but normally held out of engagement by fluid pressure in a chamber formed between the modulator piston and the second actuating piston, the pressure in the chamber also holding the modulator piston in the first position.

Abstract: An anti-skid braking system for vehicles includes a connection between a master cylinder and each wheel brake by-passing a modulator for modulating the braking pressure in the event of a skid. Each by-pass connection is controlled by a valve and all the by-pass valves are normally maintained closed by a single piston responsive to the same fluid pressure which operates the modulator. The system may also include valves for isolating the modulator from the wheel brakes when the by-pass valves open.

Abstract: In an actuator assembly for an hydraulic braking system the effective volume of a chamber through which hydraulic fluid under pressure is supplied to a wheel brake is adapted to be varied between a minimum and a maximum value by movement of a piston assembly working in a bore in communication with the chamber. An actuator piston having first and second different faces of different areas normally holds the piston assembly in a position in which the effective volume of the chamber is at a minimum until equal hydraulic pressures are applied to the areas of the actuator piston to cause the actuator piston to retract and permit the piston assembly to be withdrawn whereby the effective volume of the chamber is increased.