Abstract: A vehicle braking system has a master cylinder, a first brake associated with a front wheel of the vehicle and a second brake (11) associated with a rear wheel of the vehicle, the master cylinder being connected to the first and second brakes in a common circuit. The second brake includes brake actuator (10) with a valve (30, 35) which will vary the rate at which fluid pressure is applied to the brake actuator (10) at a predetermined brake pressure, a spring loaded lever (50) acts on the valve (30, 35) to set the predetermined pressure at which the rate of application of pressure is varied and a linkage mechanism (70) varies to loading of the lever (50) to vary the predetermined pressure in proportion to the load applied to the rear wheel with which the brake (11) is associated.

Abstract: A duo-servo brake comprising a pair of arcuate brake shoes within a brake drum, automatic operating means being located between opposed shoe ends for adjusting the clearance between shoes and drum characterized by the provision of a pair of pivotable adjuster plates having pawls each pawl being engageable with a ratchet toothed adjuster wheel whereby when the shoes are moved by drag from the drum upon brake actuation the automatically operated means enables pivotable movement of one or other adjuster plate to cause its pawl to ride over a ratchet wheel tooth, springs subsequently causing the wheel to rotate a screw-threaded means to automatically adjust the clearance between one or other of the shoes and the drum.

Abstract: A dual pressure modulating valve unit for a motor vehicle braking system has two identical valves arranged side-by-side in a common housing, each valve being for inclusion in separate sub-systems of a split braking system. The valves are of the pressure limiting or pressure reducing type wherein the pressure at which the valves start to reduce or limit the outlet pressure is determined by a biassing load on the valve plungers. The biassing loads are provided by a beam which normally divides the load of a single biassing spring equally between each plunger. In the event of a failure in one sub-system the plunger of the valve in the other sub-system receives the full load of the spring so that the pressure at which that valve starts to limit or reduce is substantially increased.

Abstract: The invention relates to vehicle braking system pressure modulating valves of the kind in which, above a first threshold of master cylinder pressure, the brake pressure increases with increasing master cylinder pressure but at a reduced rate, this rate being increased when a second threshold of master cylinder pressure is reached.In the valve according to the invention a primary plunger and a secondary plunger are carried in separate bores in the valve housing, there being a lost motion connection between them. Primary spring determines the first threshold pressure and secondary spring determines the second threshold pressure.

Abstract: A hydraulic pressure control valve for a vehicle hydraulic braking system and of the type that is normally interposed between the brake master cylinder and the rear brakes so as to ensure that after a predetermined pressure is reached in the system a further pressure increase in the master cylinder produces a lesser increase in the rear brakes than in the front brakes. The predetermined pressure at which the valve begins to operate is controlled according to the load on the vehicle suspension, by a lever and control springs which are operated by changes in height of the vehicle chassis relative to the unsprung portion of the vehicle. The pressure control valve is made compact by having a control spring co-extensive with a part of the lever.

Abstract: A valve device for use in split liquid pressure vehicle braking systems to control rear brake pressure comprises a plunger assembly in a cavity in a housing, the cavity being closed at one end. The plunger assembly has a central land between two smaller end lands. The central land slides within a central portion of the cavity which is between two smaller portions of that cavity. The central portion and the closed end portion of the cavity are formed in a main valve body and the other cavity portion is formed in another body which is carried by the main valve body. The plunger assembly carries a bar which co-operates with the shoulder between the central portion and the closed end portion of the cavity and with a valve unseating pin to unseat a ball in a passage through the central land. A biasing spring urges the plunger assembly towards the closed end of the cavity against the action upon the plunger assembly of front brake pressure which acts between the plunger assembly and the closed end of the cavity.