Commercial Driver License (CDL) Class B Practice Test

Is the use of brakes on a long, steep downgrade only a supplement to the braking effect of the engine?

1. True

2. False

3. Only in wet conditions

4. Only for heavy vehicles

The correct answer is: True

The statement that the use of brakes on a long, steep downgrade is only a supplement to the braking effect of the engine is accurate. When descending a long or steep incline, relying solely on brakes can lead to overheating and reduced effectiveness due to brake fade. Instead, the engine's braking system, often through downshifting, plays a crucial role in controlling the vehicle's speed. This method allows the engine to assist in deceleration, thereby reducing the reliance on the brake system alone. Using the engine brake helps manage the vehicle's speed efficiently and safely during steep descents. However, it's important to remember that the traditional brake system is still necessary to maintain control and to provide additional stopping power when needed. Thus, while the engine braking effect provides a significant advantage in managing speed on downgrades, the use of brakes remains essential for full stopping capability, making them a supplementary measure rather than the primary means of control.