CDL General Knowledge TestDriving SafelyMedium
To prevent a runaway vehicle when parked on a grade, in addition to setting the parking brake, what crucial step should a commercial driver take?
- AEngage the engine retarder to hold the vehicle.
- BLeave the transmission in neutral to allow for easy restart.
- CPlace chocks under the wheels.
- DTurn the steering wheel sharply towards the center of the road.
Show answer & explanationAnswer & explanation
Correct answer: C. Place chocks under the wheels.
When parked on a grade, wheel chocks provide an additional, mechanical layer of security against the vehicle rolling, even if the parking brake fails. They are a critical safety measure for preventing runaway vehicles.
Why the other options are wrong
- A. Engine retarders are for slowing a moving vehicle, not for holding a parked vehicle.
- B. Leaving in neutral removes a layer of mechanical resistance and is unsafe on a grade.
- D. Turning wheels can help if the parking brake fails and the vehicle rolls, but chocks are a primary preventative measure.
Securing Vehicle on a Grade
Procedures to ensure a commercial vehicle remains stationary when parked on an incline or decline, preventing accidental rolling.
- Parking brake is primary.
- Wheel chocks are secondary, crucial backup.
- Gear selection adds resistance.
- Steering wheel position can guide vehicle if it rolls.
Memory trick: Park on a hill? Chock it, chill!