CDL Combination Vehicles TestCoupling and UncouplingHard
After successfully coupling the tractor to the trailer, and before raising the landing gear, what is the crucial final check to confirm the security of the connection and prevent separation?
- ACheck the trailer tires for proper inflation and wear.
- BEnsure the fifth wheel release arm is in the 'locked' position and secured.
- CVisually inspect the air and electrical connections for proper seating.
- DAdjust the trailer's air pressure regulator to the correct setting.
Show answer & explanationAnswer & explanation
Correct answer: B. Ensure the fifth wheel release arm is in the 'locked' position and secured.
Even after a successful pull test, ensuring the fifth wheel release arm is fully in the 'locked' position and secured (e.g., with a safety clip) is a final critical step to prevent accidental uncoupling during transit.
Why the other options are wrong
- A. Trailer tire inspection is part of the pre-trip, not a specific step for confirming coupling security.
- C. Inspecting air/electrical is important, but the release arm ensures the mechanical connection.
- D. The trailer's air pressure regulator is not an adjustment made during standard coupling procedures.
Fifth Wheel Release Arm Security
After coupling, the fifth wheel release arm must be fully pushed in and often secured with a safety latch or clip to prevent accidental activation and trailer separation.
- Prevents accidental uncoupling.
- Often involves a safety latch or pin.
- Critical final check before driving.
Memory trick: Lock the Latch, Lest you Crash.