CDL General Knowledge TestCombination Vehicles (if applicable)Medium
What is the primary danger of coupling a tractor to a trailer on an uneven surface?
- AThe electrical cable may not reach the trailer's electrical receptacle.
- BIt will cause excessive wear on the tractor's suspension system.
- CThe air lines may become tangled during the coupling process.
- DThe kingpin may not properly seat in the fifth wheel locking jaws.
Show answer & explanationAnswer & explanation
Correct answer: D. The kingpin may not properly seat in the fifth wheel locking jaws.
Coupling on an uneven surface can cause the tractor and trailer to be at different angles, preventing the kingpin from properly aligning and seating fully into the fifth wheel locking jaws. This can result in a false or incomplete coupling, leading to the trailer detaching during operation.
Why the other options are wrong
- A. The electrical cable length is generally sufficient, and this is a minor concern compared to an unsafe coupling.
- B. While some stress may occur, it's not the primary danger; the risk of an uncoupled trailer is far greater.
- C. While possible, tangled lines are a minor issue compared to an uncoupled trailer.
Uneven Surface Coupling
Coupling on an uneven surface increases the risk of improper kingpin engagement, leading to an unsafe and potentially detached trailer.
- Causes misalignment.
- Kingpin may not lock.
- Trailer detachment risk.
Memory trick: Uneven ground, unsafe sound; keep it flat, or risk a breakdown.