tests.get-dpt-app

In a vehicle with dual parking control valves, once air pressure is lost and the spring brakes come on:

In a vehicle with dual parking control valves, there is a separate air tank that can be used to temporarily release the spring brakes if they have been activated due to low air pressure. Pushing in the proper control will release the spring brakes for a short period of time, allowing the driver to move the vehicle in an emergency.