CDL General Knowledge TestCombination Vehicles (if applicable)Hard
A driver is backing a combination vehicle and needs to turn the trailer to the left. To initiate this maneuver, how should the driver initially steer the tractor?
- AKeep the tractor's steering wheel straight.
- BApply the trailer hand valve to pivot the trailer.
- CSteer the tractor gently to the left.
- DSteer the tractor sharply to the right.
Show answer & explanationAnswer & explanation
Correct answer: D. Steer the tractor sharply to the right.
When backing a combination vehicle, you steer the tractor in the opposite direction you want the trailer to go. To make the trailer go left, you must initially turn the tractor's steering wheel sharply to the right. This pushes the rear of the tractor to the right, which in turn angles the trailer to the left. Once the trailer starts to turn, you must quickly counter-steer the tractor to follow the trailer.
Why the other options are wrong
- A. Keeping the wheel straight would make the vehicle back in a straight line, not turn the trailer.
- B. Applying the trailer hand valve would brake the trailer, not steer it, and could cause a jackknife.
- C. Steering left would cause the trailer to move right, or push the tractor under the trailer.
Backing Combination Vehicles
When backing a combination vehicle, to turn the trailer in a desired direction, the tractor's steering wheel must initially be turned in the opposite direction.
- Counter-intuitive steering.
- Small, quick steering corrections.
- Constant mirror use is essential.
Memory trick: Turn the wheel the opposite way, then follow the trailer's sway.