Abstract: The concern is with reducing the deceleration rate of an over-running flywheel following actuation of an associated camming means, by reducing the torque of an axially biassed clutch, to provide a more reliable wheel speed analogue. In one construction the clutch may consist of two clutch discs engaging with the thrust member of a camming means. The clutch torque is reduced following expansion of the camming means by reducing the frictional engagement force between one disc and the thrust member, this being effected by a change in the mechanical advantage of a lever acting on the flywheel as the lever accommodates expansion of the camming means. In another construction the fluid pressure force on a clutch biassing piston is varied to vary the clutch torque, and in yet other arrangements, a magnetic clutch biassing force is varied.

Abstract: In an hydraulic anti-skid braking system for a vehicle a supply of fluid from a master cylinder is modulated by a modulator assembly in accordance with skid signals from a skid sensing means device, and an hydraulic pump incorporating at least one plunger has a working chamber in communication with the modulator assembly to control brake re-application following skid correction. The modulator assembly incorporates a piston which is normally urged into an advanced inoperative position against a stop by a spring, in which position the piston holds a spring-loaded valve in an open position to place the master cylinder in communication with the brake. Support and expander chambers on opposite sides of the piston are interconnected at all times by a restricted passage with the support chamber defined in a bore in which the piston is guided to slide, between the piston and normally closed dump valve.

Abstract: An anti-skid hydraulic braking system for a vehicle includes a modulator which in response to a skid signal at a skid point is operative to relieve the brake-applying pressure at a braked wheel by displacing fluid from the brake. The modulator includes a brake-application restrictor which is operative to control the rate at which the brake-applying pressure from a source can be re-applied to the brake at the cessation of the skid signal, and a valve assembly is incorporated to by-pass the re-application restrictor. The valve assembly comprising first and second valve members which are relatively movable between a spaced inoperative position in which unrestricted communication is provided between the source and the brake and an operative position in which the valve members are urged into engagement to render the restrictor effective.

Abstract: A vehicle brake control device especially suitable for load carrying vehicles comprises a device for sensing front and rear brake pressure and vehicle deceleration, and a control device for maintaining the relationshipAP.sub.1 -BP.sub.2 +C=Dfwhere P.sub.1 is the front brake pressure, P.sub.2 is the rear brake pressure, f is the sensed deceleration, and A,B,C and D are constants with A greater than B.