Lucas Industries Limited

Alfred Yardley

Glyn P Farr

Ivan Mortimer

John F Pickering

In a master cylinder of the quick-fill type, communication between the quick-fill chamber (8) and the reservoir (13) is controlled by a valve assembly comprising a pressure responsive valve which opens when the pressure in the quick-fill chamber (8) reaches a predetermined level, and a one-way valve (20, 22) which allows free flow of fluid from the reservoir to the quick-fill chamber. The valve member (20) and seat (15) of the pressure responsive valve have confronting surfaces which define between them, when the valve is closed, a restrictive passage for pressure equalization purposes, and any dirt becoming trapped between the surfaces is washed away by the fluid flow on opening of the valve.

Brake master cylinder

An hydraulic brake actuator comprises opposed pistons which work in bore portions in a housing and fluid pressure in a pressure chamber urges the pistons in opposite directions to separate adjacent ends of a pair of brake shoes. A pressure proportioning valve controls communication between pressure spaces constituted by the pressure chamber. The valve is normally open to equalize the pressure in the pressure spaces but closes at a predetermined pressure so that any further increase in pressure is operative in only one pressure space, the pressure in which space acting to keep the valve closed. In use in a brake of the one-leading one-trailing shoe-drum type the increased pressure acts on the piston which applies the trailing shoe to the drum, in order to equalize the torque.

Hydraulic actuator for a vehicle internal shoe-drum brake

A servo booster is provided with a tube coaxial with the booster output rod for relieving the booster housing of braking reaction forces. The housing of a tandem master cylinder has an externally threaded rear end which is threadedly engaged with internal threads formed on a reduced diameter front part of the tube. The retracted position of the primary piston of the master cylinder is determined by abutment with the booster output rod, and this can be adjusted by turning the master cylinder housing relative to the tube.

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Kidderminster, United Kingdom

Alfred Yardley