Answer :
Answer: Relay valves
Explanation:
The service line is connected to the relay valves on the trailer to apply more or less pressure to the trailer brakes. They connect the trailer air tanks to the trailer air brakes.
Answer: Relay valves
Explanation:
The service line is connected to the relay valves on the trailer to apply more or less pressure to the trailer brakes. They connect the trailer air tanks to the trailer air brakes.