CDL Combination Vehicles TestDriving Combination Vehicles SafelyHard
A commercial driver is operating a combination vehicle on a winding rural road. The driver notices that the trailer is beginning to sway from side to side. What is the most effective immediate action to correct trailer sway?
- AApply the trailer hand brake gently and smoothly.
- BIncrease speed slightly to 'pull' the trailer straight.
- CApply the service brakes firmly and continuously.
- DSteer sharply in the opposite direction of the sway.
Show answer & explanationAnswer & explanation
Correct answer: A. Apply the trailer hand brake gently and smoothly.
Gently and smoothly applying the trailer hand brake (if available and safe to do so) will help to straighten out the trailer by applying braking force directly to the trailer wheels, pulling it back in line with the tractor. This action slows the trailer more than the tractor, which can reduce sway.
Why the other options are wrong
- B. Increasing speed can worsen sway and make it more difficult to control.
- C. Applying service brakes firmly and continuously can cause the tractor to slow down too quickly relative to the trailer, increasing the risk of jackknifing.
- D. Steering sharply can exacerbate the sway or lead to loss of control, potentially causing a rollover or jackknife.
Trailer Sway Correction
To correct trailer sway, gently and smoothly apply the trailer hand brake to pull the trailer back into alignment with the tractor.
- Sway can be caused by wind, uneven load, or speed.
- Trailer hand brake applies braking force only to trailer.
- Avoid sudden steering or heavy service braking.
Memory trick: Trailer's wagging? Gently snagging with the brake, no lagging!