Before a drive, ensure that air flows to all trailers by:

Question

Before a trip, ensure that air in the air brake system reaches all trailers. Do this by waiting for air pressure to build, then sending air to both the emergency and service lines and opening the shut-off valves on the rear of the last trailer. If air escapes from the shut-off valves in the rear of the combination, the air is being supplied to the entire vehicle.

Accepted Answer

Opening the rear shut-off valves and listening for escaping air.

Answer

Closing the rear shut-off valves and listening for escaping air.

Answer

Disconnecting air supply lines and listening for escaping air.

Answer

Rolling each trailer down a hill and testing the brakes.