Actuating mechanism for a disc brake

An actuating mechanism for a disc brake, incorporating:

• a piston coupled to a brake pad,
• a wedge having a pair of slightly convergent inclined surfaces moveable longitudinally, under the effect of a control component, along a transverse direction relative to a direction of movement of the piston and between facing surfaces forming part of the piston and of a reaction component, respectively, each of the facing surfaces being essentially parallel to a respective inclined surface of the wedge, and
• at least one pair of rollers with each roller situated on a side of the wedge and able to roll between the inclined surfaces of the wedge and the facing surfaces of the piston and reaction component, characterized in that space situated between the facing surfaces of the piston and reaction component in which the wedge and rollers are able to move, is defined as a closed chamber filled with hydraulic fluid, and that the control component is a control rod which, entering into the closed chamber by a variable amount according to longitudinal movements of the rod from a rest position, determines in the chamber variations in volume which produce a hydraulic thrust on the piston with resulting movement of the piston being slightly greater than movement which the wedge would communicate mechanically to the piston by means of the rollers for a similar movement of the control rod and in the absence of hydraulic fluid enclosed in the closed chamber.