CDL General Knowledge TestCombination Vehicles (if applicable)Medium
A driver is preparing to couple a tractor to a semi-trailer. After backing the tractor under the trailer and before raising the landing gear, what is the next critical step to ensure a secure coupling?
- ARaise the trailer landing gear fully.
- BConnect the electrical cable and air lines.
- CVisually inspect the fifth wheel locking jaws.
- DPerform a 'tug test' to check the connection.
Show answer & explanationAnswer & explanation
Correct answer: C. Visually inspect the fifth wheel locking jaws.
After backing under the trailer, the immediate next step before a tug test or raising landing gear is to visually confirm that the fifth wheel locking jaws have closed securely around the kingpin shank. This visual check is crucial for safety.
Why the other options are wrong
- A. Raising the landing gear before visually confirming the lock can lead to serious accidents if the coupling is not secure.
- B. These connections are done after confirming the mechanical coupling.
- D. The tug test is performed *after* the visual inspection of the locking jaws.
Fifth Wheel Locking Jaw Inspection
The visual check to ensure the fifth wheel's locking jaws are properly closed around the trailer's kingpin shank, confirming a secure mechanical connection.
- Performed immediately after backing under the trailer.
- Precedes the tug test and raising landing gear.
- Critical for preventing accidental uncoupling.
Memory trick: Back, Look, Tug, Connect, Lift, Inspect.