North Carolina CDL Air Brakes Practice Test

Using only the brakes on long downgrades is discouraged primarily because it can lead to overheating and failure of the brake system. When a vehicle descends a steep incline, the brakes are applied continuously to control speed and prevent the vehicle from gaining too much momentum. This prolonged use generates significant heat due to friction between the brake components. If the brakes become too hot, their effectiveness diminishes—a phenomenon known as brake fade. Once the brakes fade, the driver may find it increasingly difficult to slow down or stop, posing a serious safety risk. Therefore, to maintain control and safety, it is advised to use a combination of engine braking and the brakes instead of relying solely on the braking system. This method helps manage speed without risking overheating, ensuring that the brakes remain functional throughout the descent.