Arizona Air Brakes CDL Practice Test

What should you do to cool down hot brakes on a long descent?

1. Use air pressure to cool them down

2. Apply them frequently to maintain control

3. Let them cool by avoiding constant pressure

4. Stop completely to allow for cooling

The correct answer is: Let them cool by avoiding constant pressure

To effectively cool down hot brakes during a long descent, it is important to allow the brakes to cool naturally without maintaining constant pressure. This can be accomplished by intermittently applying the brakes and then allowing them to rest. When brakes are used continuously, they build up heat, which can lead to brake fade, where the braking effectiveness diminishes. By briefly letting the brakes cool, you prevent overheating and maintain safer control of the vehicle. This method prevents the brakes from becoming excessively hot, thus preserving their performance for when they are needed again. Avoiding the application of constant pressure allows for air circulation around the brakes, which aids in cooling them more efficiently.