CDL General Knowledge TestCombination Vehicles (if applicable)Medium
When driving a loaded combination vehicle down a long, steep grade, which of the following is the MOST effective method to control your speed and prevent brake fade?
- AShifting into neutral and allowing the vehicle to coast, using the foot brake only when necessary.
- BShifting into a lower gear and using the engine brake, supplementing with light, continuous foot brake pressure.
- CRiding the foot brake lightly and continuously to maintain a constant, slow speed.
- DIntermittently applying the foot brake firmly until the vehicle slows, then releasing it completely.
Show answer & explanationAnswer & explanation
Correct answer: B. Shifting into a lower gear and using the engine brake, supplementing with light, continuous foot brake pressure.
Using a lower gear and the engine brake, combined with intermittent, firm braking, allows the engine to help slow the vehicle, reducing the strain on the service brakes and preventing them from overheating and fading.
Why the other options are wrong
- A. Shifting into neutral is extremely dangerous as it removes engine braking entirely, leading to uncontrolled acceleration and brake failure.
- C. Light, continuous braking causes constant friction and heat buildup, leading to rapid brake fade.
- D. This is known as 'stab braking' and is effective for emergency stops but not for long descents, as it can still lead to brake fade.
Controlled Braking on Grades
A technique for descending long, steep grades in combination vehicles that involves using a low gear and engine braking, supplemented by intermittent, firm applications of the service brakes.
- Prevents brake fade by reducing heat.
- Maintains vehicle control.
- Requires selecting the correct gear before descent.
Memory trick: Gear low, brakes cool, control the roll.