Arizona Air Brakes CDL Practice Test

What is the proper method for descending long grades with an air brake system?

1. Use a low gear and push hard on the brakes

2. Let up on the brakes from time to time to cool them

3. Use a low gear and apply constant, light pressure on the brakes

4. Apply brakes just hard enough to reduce speed to five mph below safe speed then release until back to safe speed and repeat process

The correct answer is: Apply brakes just hard enough to reduce speed to five mph below safe speed then release until back to safe speed and repeat process

The method of descending long grades with an air brake system is crucial for maintaining control of the vehicle and ensuring safety. The correct approach emphasizes applying the brakes just hard enough to slow down to a safe speed without overheating or losing effectiveness, which is outlined in the chosen answer. When descending a steep hill, it is important for the driver to manage the speed effectively. By applying the brakes to reduce speed to a manageable level, the driver can then release the brakes to allow them to cool and regain effectiveness. This technique helps prevent brake fade, which can occur when brakes become too hot from continuous pressure. By repeating this process, the driver effectively keeps the vehicle within safe speed limits while also allowing the air brakes to remain in good working condition. In contrast, using a low gear and pushing hard on the brakes continuously risks overheating and can lead to brake failure due to heat buildup. Letting up on the brakes from time to time might not provide the necessary control if the driver is not reducing speed adequately. Applying constant, light pressure on the brakes might not be sufficient to manage the descent effectively, especially if the grade is steep. Hence, the chosen strategy emphasizes control, safety, and the effective management of vehicle speed when navigating long descents.