Lucas Industries Public Limited Company

Lucas Industries Limited

Arvinmeritor Light Vehicle Systems (uk) Limited

David Parry

Anthony G Price

Roy Campbell

Andrew P Green

Mark Batchelor

Michael Williamson

Graham J Gornall

Michael A Taylor

Andrew R Broadwell

A hydraulic brake valve comprising a body, a passageway defined in the body, an inlet to the passageway, an outlet from the passageway and a movable valve member in the passageway, the valve member is movable between a first position blocking the passageway to prevent communication between the inlet and the outlet, and a second position opening the passageway to allow communication between the inlet and the outlet in response to a pressure differential exceeding a predetermined value. The valve member remains in its second position once it has been moved to its second position.

Hydraulic brake valve

A liquid-immersed disc brake has a housing containing rotatable and stationary members operated by a wedge device for brake actuation from actuating means. The brake is supplied with cooling liquid, of which the flow is controlled by a valve, a portion of which is incorporated into the housing. The valve is closed by action thereon of the actuator means and opened so as to admit cooling liquid to the brake as a result of the actuator means performing an actuating movement.

Liquid-immersed disc brake

In a self-energizing disc brake of the spreading type the actuator mechanism incorporates a restrictor in the form of a circumferentially extending discontinuous oil-seal which co-operates with radial faces on the two pressure plates. A secondary, or elevated, reservoir for liquid is therefore defined between said pressure plates by said oil-seal. Liquid can escape from this reservoir in order to enhance the cooling of the braking surfaces, defined by engagement of rotatable friction discs with end faces of a housing, pressure plates and a planar non-rotatable disc. In the brake shown in FIG. 6 two annular members act as seals on the ends of the outermost friction discs.

Self-energizing disc brakes

In a self-energizing disc brake of the spreading type the recesses in the pressure plates in which the balls are housed, are machined directly into the material of the plates on pitch circles in the two plates of corresponding diameters. Each recess comprises an inclined ramp surface terminating at opposite ends in first and second end portions of which the end portion at the deeper end is engaged by the ball in an 'off' position of brake, and the second portion is engaged by the ball to preclude further relative angular movement between the plates in brake-applying direction, thereby indicating a 'wear stop'. In addition ramp surfaces of different slopes may be located between the end portions so that an increased brake-applying effort towards a fully worn lining condition provides a wear warning device.

The piston of an hydraulic master cylinder is guided to slide in portions of a bore in a body on opposite sides of a port in the wall of the body by a guide portion of the piston which is disposed on the outermost side of the port and by a cylindrical, axially extending, guide part at the outer end of a radial flange on a retainer. The retainer is mounted on an extension at the inner end of the piston and forms an abutment for a return spring for the piston.

Master cylinder assembly for a vehicle braking system

In a disc brake the application of the brake is initiated by angular movement of at least one pressure plate with respect to a reaction member to cause the pressure plate to move axially into engagement with a friction disc which, in turn, is urged into engagement with a surface in a stationary housing. The angular movement is effected hydraulically by an actuator comprising a piston working in a bore of a cylinder, the axis of which is substantially at right angles to that of the brake. The piston acts through a part-spherical rocking thrust coupling associated with a pull-rod passing through the actuator with a substantial clearance, the inner end of the pull-rod being pivotally coupled to a lug on the pressure plate, and the outer end being adapted for connection to a hand lever by which the pull-rod can be moved in a brake-applying direction. A thrust member is disposed between the piston and the spherical rocking coupling and is engagable with a thrust transmitting face on the piston for sliding movement in a transverse direction with respect to the axis of the cylinder to accommodate angular movement of the pull-rod when the brake is applied. The thrust member and the coupling are biassed towards each other by a compression spring so that the thrust member is restrained from moving radially with respect to the coupling when the brake application is effected by the hand lever. In another construction the spring is omitted and the biassing is achieved by the inherent resilience of a boot for sealing the outer end of the cylinder.

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Cwmbran, United Kingdom

David Parry