Abstract: A parking brake for use primarily on railway vehicles of the mass transit type in conjunction with the service brake apparatus but operable independently thereof. A parking brake hydraulic cylinder is mechanically connected to the brake shoe hanger of the brake unit. After the vehicle has been brought to a stop, a parking brake application may be made by supplying pressure, by a handpump, to the hydraulic cylinder which also includes a lock-nut actuable by the pressure, in excess of a certain pressure for locking the parking brake hydraulic cylinder in its applied position. A relief valve is provided for relieving the hydraulic cylinder of hydraulic pressure when the application is to be released.