A ventilation device provided which includes a valve arranged in a combined spring accumulator and operating brake cylinder. On depressurization of a pressure medium chamber in the spring accumulator brake cylinder, ventilation of a spring accumulator chamber of the spring accumulator brake cylinder, from the pressure medium chamber of the operating brake cylinder, is effected. A chambers is provided on the side of a valve piston in the valve, facing away from a control chamber, which, with an open valve, connects a first working connections to this chamber and, hence, to a second working connection, arranged axially on the front side of the valve, by means of a passage provided in the valve piston.