Slack adjusters for vehicle brakes
AssigneeClayton Dewandre Company Limited
InventorRalph Coupland
Life of this patent
Estimating the term…
Abstract
A slack adjuster to be used in association with the actuating cam of an internal expanding shoe type brake comprises a body member embodying a brake-actuating arm movable around the axis of the cam shaft, a worm rotatably mounted in the body member and meshing with a worm wheel keyed to the cam shaft, a member oscillatably mounted on the body member and co-operating with a non-rotatable member to impart motion to the worm through a sprag clutch when a pre-determined angular movement of the brake-actuating arm is exceeded, and a friction clutch also in the drive from the oscillatable member to the worm and operable to dis-engage the drive if attempt is made to rotate the worm while it is still under braking load.
Claims7
An automatic slack adjuster for a vehicle brake mechanism comprising a rockably mounted actuating arm, a rotatable worm wheel on said arm meshed with said worm and adapted to be secured upon a brake camshaft, the axis of said worm being perpendicular to that of the camshaft, means connecting said arm to actuating means for rocking said arm about the axis of said camshaft during brake operation, a member pivotally mounted on said arm for oscillation about a fixed axis, means whereby said member is displaced about its pivot axis when said arm is rocked through more than a predetermined angle in the brake applying direction, motion transmitting means extending between said member and said worm comprising a unidirectional sprag clutch so constructed and arranged that whenever said arm rocks through more than said predetermined angle to rotate said camshaft in the brake applying direction the resultant pivotal displacement of said member is ineffective to rotate said worm but upon rocking of said arm in the return direction said member is effective to rotate said worm and thereby rotate said worm wheel to impart a corrective adjustment to said camshaft, a friction clutch in said motion transmitting means having frictionally engaged elements and means resiliently biasing said elements together, said biasing means providing for drive interruption in said friction clutch when the load at the brake camshaft exceeds a predetermined amount during said return movement of said member.
An automatic slack adjuster for a vehicle brake mechanism comprising a rockably mounted actuating arm rotatably mounting a worm meshed with a worm wheel adapted to be secured upon a brake camshaft, the axis of said worm being perpendicular to that of the camshaft, means connecting said arm to actuating means for rocking said arm about the axis of said camshaft during brake operation, a member mounted on said arm for oscillation about an axis parallel to said worm axis, said member having means providing a lost motion connection to a relatively stationary part on the vehicle whereby said member is pivotally displaced on its axis when said arm is rocked through more than a predetermined angle during brake operation, unidirectional sprag clutch means interposed between said member and said worm whereby whenever said arm rocks through more than said predetermined angle to rotate said camshaft in the brake applying direction the resultant rocking displacement of said member is ineffective to rotate said worm but upon return movement rocking displacement of said member is effective to rotate said worm and thereby rotate said worm wheel to impart a corrective adjustment to said camshaft, and a friction clutch having frictionally engageable elements connected respectively to said unidirectional sprag clutch means and said oscillatable member and means resiliently biasing said elements together, said biasing means providing for drive interruption in said friction clutch when the load at the brake camshaft exceeds a predetermined amount during said return movement of said member.
Dependencies are inferred from the claim text.