Actuating and adjusting mechanism for disc brakes

In a disc brake, a rotor having a pair of friction faces, a pair of friction elements disposed adjacent each of said friction faces, a torque member mounted adjacent said rotor, a caliper slidably mounted on said torque member and straddling said rotor for urging said friction elements into frictional engagement with said friction faces when a brake application is effected, said caliper including a housing, actuating means carried by said housing, said actuating means including an extensible force-transmitting member slidably mounted in said housing and movable therein in a direction generally parallel to the axis of rotation of the rotor, one end of said extensible member being adapted to operably engage one of said friction elements for transmitting brake actuation forces to the latter when a brake application is effected and to limit retraction of the one friction element when the brake is released, means engaging the other end of said member for urging the latter toward the rotor when a brake application is effected, automatic adjustment means responsive to movement of said extensible member in excess of a predetermined amount to extend said extensible member and thereby limit retraction of said friction element to said predetermined amount, and manual adjustment means for extending said extensible member to thereby effect a manual adjustment and for retracting said extensible member to allow the friction elements to move away from said rotor a distance greater than said predetermined amount when the brake is serviced, said extensible member including a pair of coaxial, relatively rotatable components arranged so that one of said components extends from, or retracts into, the other component upon relative rotation between said components, and a piston adapted to be engaged by one end of said one component to provide a force transmitting back to one of said friction elements when a brake application is effected, said automatic adjustment means including a ratchet mechanism carried by said one component and by said piston for effecting rotation of the one component in a direction extending it from the other component when an automatic adjustment of said brake is effected, said manual adjustment means including gearing means for rotating said other component upon rotation of the gearing means, and means frictionally engaging the wall of said housing and engaging said one component, said frictionally engaging means yielding when the force applied to the manual adjusting means attains a level sufficient to overcome the frictionally engaging force between the housing and the frictionally engaging means to prevent damage to the manual adjusting means.