How does a driver test that the trailer emergency brakes are working on a doubles/triples combination?

Question

Accepted Answer

Charge the system, confirm the trailer rolls freely, then pull the air supply control to "emergency" and gently pull against the trailer with the tractor to confirm the brakes hold

Answer

Disconnect the emergency line entirely and drive forward to see if the trailer stops on its own

Answer

Apply the foot brake pedal once and listen for the low-air buzzer

Answer

Lower the landing gear and attempt to pull away from the trailer