CDL Combination Vehicles TestCoupling and UncouplingEasy
Before coupling, the tractor's fifth wheel should be positioned so that the jaws are open and the fifth wheel plate is tilted:
- AUpward towards the front of the tractor.
- BDownward towards the rear of the tractor.
- CUpward towards the rear of the tractor.
- DCompletely flat and level.
Show answer & explanationAnswer & explanation
Correct answer: B. Downward towards the rear of the tractor.
For safe and proper coupling, the fifth wheel plate should be tilted downward towards the rear of the tractor. This allows the kingpin to slide smoothly into the fifth wheel throat and engage the locking jaws.
Why the other options are wrong
- A. Tilting upward would make it difficult for the kingpin to enter.
- C. Tilting upward at the rear would prevent proper kingpin entry and locking.
- D. A completely flat plate can make kingpin entry difficult and increase the risk of high coupling.
Fifth Wheel Coupling Position
The correct orientation of the fifth wheel plate (tilted down towards the rear) and the state of its jaws (open) prior to backing under a trailer for coupling.
- Jaws open and ready.
- Plate tilted down at rear.
- Helps kingpin slide in.
- Prevents high coupling.
Memory trick: Open jaws, tilt down, and couple with a frown!