CDL General Knowledge TestDriving SafelyMedium
A commercial driver is preparing to descend a long, steep grade. To prevent brake fade and maintain control, what is the most appropriate action before starting the descent?
- AShift to a higher gear to conserve fuel.
- BPump the brakes continuously to keep them warm.
- CSelect a low gear that allows the engine to hold back the vehicle.
- DMaintain current speed and rely solely on the service brakes.
Show answer & explanationAnswer & explanation
Correct answer: C. Select a low gear that allows the engine to hold back the vehicle.
Before descending a long, steep grade, the driver should select a low gear that allows the engine to provide significant braking power (engine braking). This reduces reliance on the service brakes, preventing them from overheating and fading.
Why the other options are wrong
- A. Shifting to a higher gear would increase speed and reduce engine braking, making the situation more dangerous.
- B. Continuously pumping the brakes can lead to air loss in air brake systems and still cause overheating.
- D. Relying solely on service brakes on long, steep grades will quickly lead to overheating and brake fade, resulting in loss of braking power.
Safe Mountain Descent
The technique of using engine braking in a low gear to control vehicle speed on long, steep downgrades, preserving the service brakes.
- Use engine braking
- Select low gear before descent
- Avoid brake fade
Memory trick: Gear Down, Slow Down, Stay Safe.