Patent ID: 7845474

Claim:
A combined service brake and spring type brake cylinder, comprising: a) a diaphragm, which is situated in a housing of the service brake cylinder and may be impinged with pressure, and which delimits a service brake chamber, which may be impinged with a service brake pressure, on one side and a chamber receiving a return spring on the other side; b) a spring type brake piston, which is situated in a housing of the spring type brake cylinder and is actuatable by a storage spring, which delimits a spring type brake chamber on one side and a spring chamber receiving a storage spring on the other side, and has a piston rod, which carries a ventilation valve, which produces or blocks a flow connection between the spring chamber and the service brake chamber; c) wherein the ventilation valve contains a piston, working together with a valve seat, which is loaded by the pressure in the spring chamber in the open position and which releases a flow cross-section in its position lifted off of the valve seat; d) wherein the ventilation valve contains at least one further piston, which works together with a further valve seat, and is loaded by the pressure in the spring chamber in the open position and by the pressure in the service brake chamber in the closed position, and which, in its position lifted off of the further valve seat, releases at least one further flow cross-section; and e) wherein, with an applied parking brake and a simultaneously actuated service brake, having service brake pressures which are at least one of less than a pressure threshold and less than a pressure gradient threshold, the one piston is lifted off of the valve seat and the further piston forms a seal against the further valve seat.