Self-energizing disc brakes

摘要

A spreading disc brake is actuated for parking or braking in an emergency by a brake-applying mechanism which comprises a pivotally mounted lever in the form of a bell-crank, and a pull-rod coupled to the lever. The inner end of the pull-rod is provided with an eye of which the inner side of the outermost end has a rocking and sliding engagement with a complementary arcuate face defining a notch in the innermost edge of the longer arm of the lever. The coupling between the pull-rod and the lever enables the pull-rod to adopt a substantially radial alignment with the brake center of rotation, even when brake lining wear progressively increases the brake forward to reverse articulation. The lever is pivotally mounted on one of the pressure plates by a pivot pin, and has a cranked nose which is received within the groove in the other pressure plate. In order to prevent the lever from twisting when the brake is applied, the lever reacts against reaction faces of which the face comprises a wall defining the outer side of the groove, and the face comprises a region on the pressure plate on the radially outermost side of the pin.