AUTOMATIC PARKING BRAKE DEVICE

摘要

An automatic parking brake device where a parking piston (23) is slidably installed in a casing (22) and a lock mechanism (25) is provided in the casing (22), behind the parking piston (23). The parking piston (23) can provide a parking brake ON state when the piston is advanced according to the action of a parking brake control liquid pressure applied to the back face of the piston. In order to mechanically lock the parking piston (23) at an advanced position, the lock mechanism (25) automatically activates locking according to the advancement of the parking piston (23). The lock mechanism (25) releases the locking according to the action of a parking brake release control liquid pressure. The parking brake control liquid pressure and the parking brake release control liquid pressure are obtained by controlling the pressure of a liquid from a liquid pressure source by liquid pressure controlling means. The structure above enables an automatic parking brake ON state to be obtained by a simple structure without involving electric power consumption.