Tractor-Trailer Practice Test

The function of trailer brakes is primarily to stop the trailer separately from the tractor. This capability is essential for maintaining control during braking situations, particularly when a truck and trailer are maneuvering on varied terrain or when coming to a stop. The independent braking system ensures that the trailer can slow down or stop, which helps to prevent jackknifing and enhances overall safety.

When the trailer is equipped with its own braking system, it allows the driver to apply the brakes of the trailer independently, which is particularly useful in situations where the load may shift or when descending steep grades. This independent operation is crucial in providing better stopping power and stability, as the combined braking effort from both the tractor and trailer can reduce stopping distances and improve control.

Other options such as enhancing fuel efficiency, improving trailer aerodynamics, and assisting with steering do not directly relate to the primary purpose of the trailer brakes, which is focused solely on the safe and effective stopping of the trailer.