Lucas Industries Public Limited Company

Denis J McCann

Edwin R Carswell

Andrew John Ward

William S Broome

Colin F Ross

Allan Williams

Stuart B Dawson

In an anti-lock braking system incorporating a solenoid-operated fluid flow control valve, the rate at which fluid can normally be dumped to release a brake is increased by the provision of a pilot valve. The pilot valve is adapted to open by a pressure drop across a diaphragm. The pressure drop is established when an exhaust valve opens upon energization of the solenoid in response to an anti-lock signal.

Hydraulic anti-lock braking systems for vehicles

Brakes (3, 4) on the wheels (7, 8) on a common axle are each controlled by a separate skid control unit (16, 17) each including a memory chamber (33, 34), and a single latch valve (21) common to both units closes at the first skid point to be sensed by a sensor (11, 12) on each wheel. The rate of re-application of the two brakes is controlled in response to signals from the individual sensors, but at rates of pressure increase determined by each respective memory chamber, and by flows of pressure controlled by restrictors (47).

Fluid-pressure operated anti-skid braking systems for vehicles

A trailer air braking system has combined spring brake and service brake actuators, and the service brake chambers of the actuators are controlled by a combined emergency relay and modulator valve assembly of known construction. In order to ensure that the spring brake function does not become operative due to a moderate loss in the pressure of the trailer reservoir, such as would occur in the event of an anti-skid test in which the reservoir is isolated from the emergency line and the modulator valve is cycled, a spring brake one-way control valve is inserted into the spring brake circuit leading from the reservoir. The control valve acts in one condition as a one-way valve to prevent air returning from the spring brake actuator chamber to the reservoir, but on a large loss in reservoir pressure, a piston which carries the one-way valve seat and is subjected to reservoir pressure moves under spring biassing such that the one-way poppet valve member is unseated by a control pin to permit a reduction in spring brake pressure.

Vehicle anti-skid air braking systems

In a fluid-pressure operated anti-skid braking system operation of a brake-applying relay valve is controlled by control pressure in an application chamber. A memory chamber is charged on initial brake application with pressure from supply passage connected to a brake actuator through one-way valve and an orifice permits pressure in the memory chamber to decay when the pressure in the supply passage reduces. This reduces the effective volume of air required for initial operation of the relay valve thereby increasing its response time. Re-application of the brake following a skid is controlled by closure of a latch valve which permits only a restricted flow of control pressure into the application chamber. This is sufficient to re-apply the brakes rapidly in a first stage until the pressure in the application chamber becomes equal to that of the decayed pressure in the memory chamber, whereafter brake re-application continues at a slower rate since the restricted flow of control pressure has also to increase the pressure in the memory chamber.

A dual brake valve assembly including two co-axial primary and secondary valves for primary and secondary braking circuits is modified to include an auxiliary exhaust valve operable in conjunction with the pressure plate and a secondary piston for controlling operation of the secondary valve in response to operation of the primary valve. When the valve assembly is operated to apply the brakes, the auxiliary exhaust valve remains closed to prevent the premature release of fluid from the primary circuit irrespective of uncontrolled relative movement between parts of the valve assembly.

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Powys, United Kingdom

Denis J McCann