Vehicle & Equipment · Driver Training VideoCoupling & Uncoupling

Set the trailer up before you back under. Level, solid ground. Trailer brakes set or wheels chocked. Nose just slightly lower than your fifth wheel, so the plate lifts the trailer as you come back. Too high and you slide under the nose and hook nothing.

Back straight and slow

Line up with the kingpin, come back until the fifth wheel just touches the trailer, stop, then back firmly under it in low gear until the jaws snap shut. You will feel it. Never back under fast and hope the jaws catch.

Then the tug test

Trailer brakes still set, low gear, gentle pull forward against them. If the trailer follows you, you are not coupled. Every coupling, every time, including the drop and hook at three in the morning.

Now get out and look

Flashlight, under the trailer, three things. Locking jaws closed around the shank of the kingpin, not the head and not in front of it. Release handle seated in the locked position with the safety latch over it. And no gap between the upper and lower plates.

Air and electrical

Red is the emergency supply line, blue is the service line. Seat both glad hands, and check that the lines are not rubbing or hanging low. Plug in the seven way, check your lights, then crank the landing gear all the way up and secure the handle.

Uncoupling is the same discipline backwards. Level, solid ground, and pads under the gear if it is soft. Set the trailer brakes. Lower the gear until it makes firm contact, then a couple more turns to take the weight, but do not lift the trailer off the fifth wheel.

Almost every dropped trailer traces back to two shortcuts: no tug test, or no look underneath. Together they cost two minutes.

Your company standard: brakes set or wheels chocked before you back under. A tug test on every coupling, no exceptions. Eyes and a flashlight on the jaws, the handle, and the plate gap before you roll. Landing gear fully up, handle secured.