PARKING BRAKE DEVICE

摘要

A parking brake device, wherein the parking brake state of a wheel brake (2A) is provided by the advancing operation of a parking piston (44) slidably fitted to a casing (23) with its rear face side facing a control fluid pressure chamber (47) for parking, and the advancing state of the parking piston (44) is mechanically locked by the pushup of spherical bodies (58) by the advancement of the lock piston (56) of a lock mechanism (31). Multiple lines of guide grooves (126) for rollingly fitting a part of the spherical bodies (58) therein are formed in the inner surface of a large diameter hole (38), a restricting step part (42), and the inner surface of a small diameter hole (39) to have an inwardly recessed curved shape in cross section and to be extended in the axial direction of an insert shaft (59). Thus, the parking brake state can be provided by a simple structure which does not consume electric power.