PNEUMATIC BRAKE ACTUATOR WITH FLOW INSENSITIVE TWO WAY CONTROL VALVE

A pneumatic brake actuator has a spring brake actuator with spring and spring brake pressure chambers, and a service brake actuator with service brake pressure and pushrod chambers. An actuator tube comprises a side wall that defines an interior space which is in fluid communication with the spring chamber. The actuator tube has a first end and a second end, the latter being positioned in the service brake pressure chamber and presents an opening. A valve body is at least partially positioned within the interior space of the actuator tube through said opening and defines a channel. A seal is positioned within the channel, wherein the seal and the valve body enclose a valve chamber that is not in fluid communication with said spring chamber or said service brake pressure chamber. The seal is moveable between an open position in which fluid can flow through the channel between the spring chamber and the service brake pressure chamber and a closed position in which fluid is blocked from flowing through the channel. The seal is biased to said open position and comprises a first surface in fluid communication with the service brake pressure chamber as well as a second surface that is in fluid communication with said valve chamber.