BRAKE ASSEMBLY

PROBLEM TO BE SOLVED: To provide a simple manual release mechanism by providing a means of energizing to energize a locking piston toward its actuating position side, moving the locking piston toward its retreating position side when pressurized fluid exists in a pressure compartment, and actuating a means of releasing including a manual operating handle by interlocking with this locking piston. SOLUTION: A gerotor motor adequately provided in a parking brake assembly is equipped with a roller gerotor gear set 15 including a rear end cap 21 seal-coupled to a valve housing part 11. The set 15 is composed of a ring member 29 having internal gears comprising plural rollers 33 and a star member 31 with external gears, and the both 29, 31 are mated with each other in order to form plural expansion/compression volume compartments 37. A locking piston 65 is disposed in a rear internal compartment 61 formed in the rear end cap 21, this is energized in a brake engagement direction by a belleville spring and can move toward the releasing side by a handle member 107 provided outside.