What happens if a driver crosses the air lines when hiking up to an old trailer without spring brakes?

When a driver crosses the air lines while hiking up to an old trailer that does not have spring brakes, the result is that the trailer will not have active brakes. The braking system relies on the air from the tractor to maintain proper functionality of the trailer brakes. If the air lines are crossed, it disrupts the supply of air in the proper sequence needed for the brakes to engage.

In this scenario, the driver may still be able to drive the vehicle, but the trailer’s brakes will not function as intended. This creates a significant safety hazard, as the driver will be operating the vehicle without the ability to effectively stop or control the trailer. It is crucial for drivers to ensure that air lines are correctly connected to prevent such situations and maintain proper braking control over both the tractor and the trailer.