CDL Combination Vehicles TestCoupling and UncouplingMedium
When backing the tractor under a trailer for coupling, it is crucial to ensure that the fifth wheel is positioned correctly. What is the correct initial position for the fifth wheel to receive the kingpin?
- AFlat and level with the jaws open.
- BTilted slightly down towards the rear with the jaws open.
- CTilted forward with the jaws closed.
- DTilted slightly up towards the rear with the jaws closed.
Show answer & explanationAnswer & explanation
Correct answer: B. Tilted slightly down towards the rear with the jaws open.
For proper coupling, the fifth wheel should be tilted slightly down towards the rear to allow the kingpin to slide in smoothly and ensure the jaws are open to receive it.
Why the other options are wrong
- A. A flat position can make coupling more difficult; a slight tilt aids entry.
- C. Jaws must be open to receive the kingpin.
- D. Jaws must be open, and tilting up would prevent the kingpin from entering.
Fifth Wheel Tilt Position (Coupling)
Before backing under a trailer, the fifth wheel should be tilted slightly down towards the rear and the jaws must be open to facilitate safe and proper coupling.
- Aids kingpin entry.
- Prevents damage to components.
- Ensures reliable coupling.
Memory trick: Down and open, ready for the kingpin token.