The ventilation device comprises a valve (39,44,49,50,40,34,14,15,37,48), arranged in a combined spring accumulator and operating brake cylinder (1,2) and, on depressurisation of the pressure medium chamber (4) in the spring accumulator brake cylinder (1), a ventilation of the spring accumulator chamber (9) of the spring accumulator brake cylinder, from the pressure medium chamber (22) of the operating brake cylinder (2), is carried out. According to the invention, the flow properties of the valve (39,44,49,50,40,34,14,15,37) may be improved, whereby a chamber (48) is provided on the side of the valve piston (39,44) in the valve (39,44,49,50,40,34,14,15,37), facing away from the control chamber (37), which, with an open valve (39,44,49,50,40,34,14,15,37), connects the first working connection (14) to the chamber (48) and hence to the second working connection (34), arranged axially on the front side of the valve, by means of a passage (43,42), provided in the valve piston (39,44).
