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, what is the NEXT critical step before raising the landing gear?
- ARaise the trailer landing gear fully.
- BConnect the glad hands and electrical cable.
- CCheck the fifth wheel locking jaws for a secure connection.
- DRelease the tractor parking brakes.
Show answer & explanationAnswer & explanation
Correct answer: C. Check the fifth wheel locking jaws for a secure connection.
After backing under the trailer, it is essential to ensure the fifth wheel locking jaws have securely closed around the kingpin. This prevents the trailer from separating from the tractor, which is a major safety hazard.
Why the other options are wrong
- A. Raising the landing gear before confirming the lock could cause the trailer to fall if not properly coupled.
- B. Connecting air and electrical lines comes after confirming the mechanical connection, but before raising landing gear.
- D. Releasing tractor brakes would be done to move the vehicle, not as an immediate step after backing under the trailer during coupling.
Fifth Wheel Locking Check
Verifying that the fifth wheel locking jaws have fully closed around the trailer's kingpin after backing the tractor under the trailer.
- Prevents trailer separation.
- Done visually and by tugging the tractor.
- Crucial safety step in coupling.
Memory trick: Back, Check, Connect, Raise, Secure, Test.