Mechanical actuator for a disc brake

A dual toggle mechanical actuator for a disc brake within a caliper assembly cooperates with at least one friction pad to engage the latter with a rotor, the caliper assembly including a housing with a bore receiving a piston assembly which is movable in the bore to engage the friction pad with a rotor, and a mechanical actuator disposed in the bore for moving the piston assembly, characterized in that the mechanical actuator comprises an easily reversible, dual toggle mechanical actuator having a cam shaft extending into the bore, a reaction toggle cooperating with the cam shaft and the housing and an output toggle disposed between the piston assembly and the cam shaft for imparting movement to the piston assembly in response to rotation of the cam shaft, each of the toggles having a pair of pivot points about which the toggles move, the reaction toggle and output toggle cooperating with grooves of said cam shaft to define asymmetric interfaces therebetween so that angular travel of said toggles is different when said cam shaft is rotated and said cam shaft moves in the direction of said piston assembly, and an end wall enclosing said bore, the reaction toggle pivoting relative to said cam shaft and relative to said end wall during a first stage of braking when said cam shaft is rotated, and said reaction toggle moving with said cam shaft to pivot relative to said end wall during a second stage of braking, the output toggle approaching a lock position and the reaction toggle attaining a lock position relative to the respective grooves when said cam shaft has completed rotation wherein longitudinal center lines of the toggles remain a distance apart along a radius of said cam shaft so that the cam shaft may be counter-rotated easily to a rest position.