What does the service line in a trailer do?

The service line in a trailer is responsible for carrying air to the trailer brakes. This air supply is crucial for the operation of the braking system on the trailer, allowing the driver to exert control when slowing down or stopping. When the driver applies the brakes in the tow vehicle, air pressure is transmitted through the service line to activate the trailer's braking system, ensuring that the trailer responds appropriately in proportion to the vehicle's braking action.

This function is vital for safe operation, as it provides the necessary braking force to the trailer, helping to prevent accidents and control the vehicle effectively during transit. The braking system’s dependency on the service line highlights its role in ensuring safety on the road by facilitating a reliable braking experience for both the driver and the trailer.