Dowell & Dowell
Air brake emergency control valves
 Control valve assemblies for regulating the parking/emergency spring brakes of a tractor trailer air brake system which include valve components for insuring that the spring brakes are not released until pressurization of the system's service reservoir is achieved and which components are operable to exhaust the spring brakes to atmosphere upon the failure of the supply pressures within the system to thereby automatically apply the spring brakes. In one embodiment, the valve components permit pressure to be supplied to release the spring brakes under circumstances when it is not possible to pressurize the service reservoir. 
Tramec Corporation
Y B
Y10T B60T
additional inventional
Sergio Edward D.
Campanini Sell