Coupling and Uncoupling
Coupling sequence
- Inspect the fifth wheel and kingpin; ensure the fifth wheel is open and greased.
- Back under the trailer slowly, aligning the tractor squarely.
- Stop before the tractor contacts the trailer and check alignment.
- Back until the fifth wheel locks; you should hear a click.
- Pull forward gently to test the lock - the trailer should not move independently.
- Connect the air lines (red to emergency/glad hand, blue to service) and the electrical cord.
- Raise the landing gear, secure the crank, and check the trailer brakes.
Uncoupling sequence
Park on level ground, apply the parking brake, lower the landing gear to firm contact, disconnect the air lines and electrical cord, release the fifth-wheel lock, and pull forward slowly.
Traps
- The most common trap is skipping the pull test. Always tug gently after coupling to confirm the lock.
- Questions ask which glad hand is which: red = emergency (supply), blue = service.
- Another trap: raising the landing gear before the air lines are connected. Connect air lines first so the trailer brakes can be tested.
- Never couple with the trailer brakes released on a slope.
Rule of thumb
Low and slow, then tug - back slowly, stop before contact, and always perform the pull test.