ON CERTAIN TUB GRINDER TRAILERS EQUIPPED WITH BENDIX SR-5 TRAILER SPRING BRAKE VALVE ASSEMBLIES, THE MOLDED RUBBER FACE OF THE INLET/EXHAUST VALVE (I/E VALVE) COMPONENT OF THE AFFECTED VALVES CAN SEPARATE FROM THE VALVE'S METAL INSERT. AIR CAN BE TRAPPED BY A SEPARATED I/E VALVE CAUSING IT TO BALLOON AND BLOCK THE EXHAUST PASSAGE OF THE TRAILER SPRING BRAKE CIRCUIT.