How can you confirm that air flows to all trailers?

To confirm that air flows to all trailers, opening the shut-off valves at each trailer and listening for air escaping is the most effective method. This approach allows the driver to verify that the air supply is reaching each trailer's braking system. When the shut-off valves are opened, there should be a noticeable sound of air escaping if the system is functioning properly, indicating that air is indeed flowing through the lines.

This method directly tests the functionality of the trailer's air brakes by ensuring they are receiving the necessary air supply to operate effectively. It also helps identify any potential leaks or issues in the system that might prevent proper brake function.

Other methods, while they may provide some insights, do not directly confirm the air flow to each trailer. For instance, closing all valves and listening for hissing could indicate a leak but won't confirm if air is reaching each component. Checking the air pressure gauge after driving gives you an overview of the system pressure but does not ensure that each trailer gets the air needed. Inspecting air lines can be beneficial for identifying visible damage or leaks but does not confirm if air is presently flowing through each trailer’s system.