CDL General Knowledge TestCombination Vehicles (if applicable)Easy
A driver is performing a pre-trip inspection of the fifth wheel assembly. Which of the following indicates a safe and properly coupled connection?
- AThe kingpin is fully seated in the locking jaws and the safety latch is engaged.
- BThe release arm is in the 'open' or 'uncoupled' position.
- CThere is a visible gap between the upper and lower fifth wheel plates.
- DThe apron plate is bent or damaged, allowing for slight movement.
Show answer & explanationAnswer & explanation
Correct answer: A. The kingpin is fully seated in the locking jaws and the safety latch is engaged.
A safe fifth wheel connection requires the kingpin to be fully secured by the locking jaws, with the safety latch engaged to prevent accidental release. Any other condition indicates an unsafe coupling.
Why the other options are wrong
- B. The release arm must be in the 'closed' or 'locked' position to secure the trailer.
- C. A gap indicates an improper or incomplete coupling, which is unsafe.
- D. A bent or damaged apron plate is a defect that compromises the stability and safety of the coupling.
Fifth Wheel Coupling Safety
A properly coupled fifth wheel ensures the kingpin is fully engaged in the locking jaws with the safety latch secured, preventing trailer separation.
- Kingpin fully seated.
- Locking jaws closed.
- Safety latch engaged.
Memory trick: Kingpin locked, safety latched, trailer attached.