Lucas Industries Public Limited Company

Lucas Industries Limited

Brian Ingram

Hugh G Margetts

Michael J England

John R Rees

David A Harries

An automatic adjuster for a vehicle brake actuator has a non-rotatable brake shoe-engaging tappet, an adjuster member having a threaded shank threadedly engaged with a nut, the adjuster member co-acting with the tappet so that said rotation of the adjuster member causes axial movement of the tappet. The adjuster member is drivingly coupled by a coupling member to a shaft having an external reversible thread and a spring acting between the tappet and shaft urges the tappet against the shoe. A clutch ring has an internal reversible thread whereby it engages the corresponding thread on the shaft and is resiliently urged towards a fixed clutch face. The clutch ring controls rotation of the adjuster member during brake actuation and release to adjust the retracted position of the tappet to compensate for wear of the brake shoe. The force provided by the spring is relieved upon brake actuation, during which adjustment occurs, so that torque applied through the clutch ring is reduced with a consequent reduction in wear of the ring.

Automatic adjuster for a vehicle brake actuator

An automatic adjuster includes a two part strut interconnected by a non-reversible thread so that extension of the strut under the influence of an adjuster device is effected by relative rotation between the two parts. The adjuster device includes a spigot, rotation of which is controlled by a clutch member as a result of a cooperation between helical teeth respectively on the strut part and spigot and also uni-directionally couples the spigot to a fixed member so that in the event of temporary clutch disengagement due to vibration, rotation of the spigot in the de-adjusting direction is prevented by rotation thereof is the adjusting direction is permitted when required.

Automatic adjuster

A hydraulic actuator for a vehicle brake incorporates an automatic adjuster which includes a strut of variable length formed by members which are threadedly interengaged by way of non-reversible screw thread connection. The member is an adjuster shaft which forms a reversible screw thread connection with a drive ring arranged to control rotation of the adjuster shaft during brake application and release. The non-reversible thread is subject, during brake application, to an axial force which is the resultant of forces derived from the braking pressure applied to different areas defined respectively by a seal on the piston and a further seal on the adjuster shaft. This ensures that random rotation of the adjuster shaft during brake application is resisted without the necessity for the application of axial spring load.

Brake actuator

An actuator for a shoe drum brake has a body containing a tappet engaging one of a pair of brake shoes, and a split tappet of which the outermost piston engages the other brake shoe. A mechanical wedge actuator acts between the tappets for emergency and parking operation. The piston cooperates with an automatic adjuster of which a component normally engages an abutment member which bears against a shoulder within the body to isolate the adjuster from the piston of the split tappet and thereby from the other tappet.

Actuator for an internal shoe drum brake

An automatic slack adjuster comprises a pair of thrust assemblies. Each thrust assembly acts between a cam and a respective shoe-end and is guided to slide axially in a bore in a housing. Each thrust assembly comprises a nut which engages with, and is held against rotation with respect to, a respective shoe-end, and a screw-threaded tappet having a piston part which slides in the bore, and an integral threaded stem of reduced diameter which is screwed through the nut. The piston parts are both provided with gear teeth to enable them to be rotated together by the engagement of a crown wheel, or a pair of pinions carried by opposite ends of a transverse shaft which is rotatable in a bore normal to a bore in which the cam shaft carrying the cam is rotatable.

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Gloucestershire, United Kingdom

Brian Ingram