CDL Combination Vehicles TestDriving Combination Vehicles SafelyMedium
A commercial driver is operating a combination vehicle and notices their trailer beginning to sway excessively, indicating potential trailer oscillation. What is the best immediate action to take?
- ASteer quickly in the opposite direction of the sway.
- BApply the trailer hand brake gently and steadily.
- CAccelerate sharply to pull the trailer straight.
- DApply the foot brake firmly and hold it down.
Show answer & explanationAnswer & explanation
Correct answer: B. Apply the trailer hand brake gently and steadily.
Gently applying the trailer hand brake (trailer brake control) helps to pull the trailer straight by creating drag on the trailer wheels, without affecting the tractor's stability. This can often correct minor sway before it becomes uncontrollable.
Why the other options are wrong
- A. Steering quickly in the opposite direction of the sway can overcorrect, leading to a more severe sway or loss of control.
- C. Accelerating sharply can worsen trailer sway by increasing centrifugal force or speed, making it more difficult to control.
- D. Applying the foot brake (service brake) can lock up the drive wheels of the tractor or cause a jackknife, especially if the trailer is already swaying.
Trailer Sway Correction
To correct minor trailer sway, gently apply the trailer hand brake to create drag on the trailer, pulling it back into alignment.
- Do not accelerate.
- Do not use service brakes.
- Gentle trailer brake application.
Memory trick: Sway? Hand brake, don't play.