Automatic slack adjuster

In a slack adjuster for connecting a brake operator to rotate a cam shaft of a vehicle brake system of the type including a housing;

• a worm gear mounted by said housing for rotation with said cam shaft about a first axis;
• a worm shaft mounted by said housing to rotate about a second axis perpendicular to said first axis and for displacement axially of said second axis in first and second axial directions, said worm shaft having opposite ends and a worm intermediate said ends engaged with said worm gear;
• a rotor and a coupling each mounted coaxially to rotate relative to one of said ends of said worm shaft;
• connecting means connecting said housing to said brake operator for rotating said housing about said first axis as vehicle brakes are applied and released;
• a link connected to said connection means and said rotor for rotating said rotor in a first direction as said vehicle brakes are applied and in a second direction as said vehicle brakes are released;
• one way clutch means tending to couple said coupling for rotation with said rotor when said rotor is rotated in said second direction and tending to uncouple said coupling from rotation with said rotor when said rotor is rotated in said first direction;
• slip means for releasably connecting said coupling to said worm shaft for rotation therewith;
• spring means tending to bias said worm shaft against movement in said second axial direction from rotational coupling engagement with said coupling via said slip means, said spring means permitting movement of said worm shaft in said second axial direction to uncouple said coupling from rotation with said worm shaft via said slip means upon a given axial loading of said worm shaft incident to operation of said vehicle brakes, the improvement comprising in combination:
• means for defining a first reference position of said rotor and a return spring for biasing said rotor for rotation in said second direction into said first reference position.