CDL General Knowledge TestCombination Vehicles (if applicable)Medium
During a pre-trip inspection, a driver notices that the fifth wheel locking jaws are not fully closed around the kingpin. What is the immediate required action?
- AAttempt to fully engage the jaws by pulling the release handle again.
- BApply grease to the fifth wheel plate to facilitate full engagement.
- CProceed with caution, as the kingpin is still partially engaged.
- DDo not drive the vehicle; re-couple the tractor to the trailer.
Show answer & explanationAnswer & explanation
Correct answer: D. Do not drive the vehicle; re-couple the tractor to the trailer.
If the locking jaws are not fully closed, the trailer is not securely coupled. Driving in this condition is extremely dangerous and could lead to the trailer separating from the tractor. The vehicle must be re-coupled correctly.
Why the other options are wrong
- A. Pulling the handle again might not fix a misaligned coupling; a full re-couple is safer.
- B. Grease is for lubrication, not for correcting a mechanical locking issue.
- C. Driving with partially engaged jaws is a critical safety violation and extremely dangerous.
Fifth Wheel Locking Check
Always verify that the fifth wheel locking jaws are fully closed and secure around the kingpin before driving a combination vehicle.
- Crucial for secure coupling.
- Partial engagement is unsafe.
- Requires full re-coupling if not secure.
- Part of pre-trip inspection.
Memory trick: Locking jaws, no flaws, or hit the pause.