CDL Vehicle Combination Practice Test

What could indicate a successful coupling of the trailer?

1. No air leaks during the inspection

2. Brake sounds heard when applying the brakes

3. The trailer remains stationary on a slope

4. Hook adequately without lowering the landing gear

The correct answer is: Brake sounds heard when applying the brakes

The indication of a successful coupling of the trailer is commonly associated with various factors that confirm the connection is secure and functional. The correct choice reflects an essential aspect of ensuring that the trailer is properly coupled. When brakes produce sounds as they are applied, especially when the trailer remains correctly coupled, it suggests that the braking system is functioning as intended, which is a key factor in vehicle safety. However, this sound itself isn’t a definitive indication of the coupling; rather, it can indicate operational elements that may not be uniquely tied to successful coupling. No air leaks during inspection serves as an important evaluation for the air brake system but doesn’t specifically address the coupling. It indicates that the air system is functioning in good order, contributing to overall vehicle safety but not directly confirming a secured coupling. The trailer remaining stationary on a slope would indeed indicate a secure connection but isn’t always the best standalone indicator, as multiple factors affect this scenario, including the grade of the slope and load distribution. The statement about hooking adequately without lowering the landing gear is a strong indicator of a successful coupling, as it demonstrates that the trailer was connected properly and the landing gear was freed appropriately, reinforcing the secure attachment. This aspect is critical in confirming that the coupling is not only successful but