How to Hook-Up a Semi-Truck and Trailer

Coupling and uncoupling a semi-truck and trailer is an essential skill for a truck driver. Nothing spells "bad day" like having a trailer slide off a fifth wheel at an intersection. However, as long as you follow the proper procedures, you can hook up a semi- truck to a trailer safely.

Instructions

1. Inspect the truck and trailer, following FMCSA guidelines. Ensure the trailer is road ready and can be safely hooked and towed down the highway. Verify the fifth wheel is in position and greased, with jaws released. If necessary, pull the release lever.

2. Look for a kingpin lock. Most models have a tag that hangs down to flag their presence. Remove it, if necessary, or find someone who can. Most locks release with keys. Failure to remove a kingpin lock before backing under the trailer will prevent the trailer from hooking the kingpin and can damage your fifth wheel.

3. Estimate the trailer's height. You're learning how to hook up a fifth wheel to a trailer, and it can take more than one try. Ideally, the trailer should touch the fifth wheel 6 inches from the bottom as you back underneath. Adjust the landing gear for proper height. If the semi is still too high, lower the suspension by dumping some air.

4. Position the tractor in a straight line in front of the trailer, fifth wheel to trailer kingpin. You can hook a trailer from a skewed position, but it's not recommended. Back up slightly under the nose of the trailer and set your tractor air brakes. Get out and reassess your position.

5. Release your brakes and reposition the semi, if necessary. Back under the trailer until the kingpin slides into position. Keep your window rolled down and you'll hear it snap into place.

6. Test the integrity of the coupling by putting the semi in first gear and moving forward no more than 6 inches. If everything is hooked properly, you can feel the tractor strain as it pulls against the trailer. Set the tractor brakes and walk back to the fifth wheel. Verify that the kingpin has locked and the fifth wheel jaws have closed. The release arm must also be in the closed position. If anything is out of place, pull the release lever and repeat Steps 4 through 6.

7. Couple the gladhands and electrical line. Raise the landing gear, and you're ready to travel.

Tips & Warnings

• Both visual and physical confirmations are necessary to ensure the that you locked the kingpin appropriately into the fifth wheel. Theses dual safety measures take only seconds and can prevent a major accident.