Safety Tips

Safety Tip Sunday | Coupling and Uncoupling a Tractor and Trailer

Brian Pickett
5 Minutes

This week’s safety tip is one you may or may not need a refresher on: Coupling and Uncoupling a tractor trailer. We’ll just cover the basics for performing this procedure and maybe give you a fresh reminder on a few things. LGT’s Safety Director, Brian Pickett has made an in-depth safety video demonstrating just this on LGT’s YouTube channel. Here’s the link to the Coupling and Uncoupling Procedure video if you’d like a visual.

A quick thing to mention before going into the details: Always remember to never leave a partially disconnected unit and ensure all unattached tractors have chocked wheels. Also, chock all tractors parked on sloped or uneven pavement because this creates a potential for unintended movement. Accidents can happen because of this, so let’s try to avoid that as much as possible. Now, let’s get into the procedure.


Being a truck driver means having to transport a wide variety of product, unloading and loading that product, and remembering to do it all safely. Knowing how to safely attach and detach a tractor trailer is an essential part of the job, so let’s walk through it.

  • The first thing to do before anything else is to check that the fifth wheel is greased and not dry. Also, check that the fifth wheel lock is in the open position and ready to accept the trailer kingpin. As you walk back to the trailer, double check that the wheels are chocked.
  • Next, start the uncoupled trailer and look to see if the tractor parking (emergency protection) valve, and trailer parking valve are in the ‘out’ position. Build trailer brake air pressure to at least 90psi. For improved visibility and hearing, open the driver side window.
  • Release the parking brake and back up so the kingpin is directly inline with the fifth wheel. Stop within 1 to 2 inches of the trailer kingpin plate. Set the tractor brakes, exit the cab, and check the height of the trailer to ensure that the fifth wheel is high enough to slightly lift the trailer. If not, adjust the height. Also, check that the kingpin is aligned with the tractor fifth wheel plate opening.
  • Now, set the cab controlled fifth wheel to the locked position. Back under the trailer until the fifth wheel locks securely. Once this is done, perform a tug test by gently pulling forward to ensure the kingpin is securely locked by the fifth wheel. Set the tractor brakes and exit the cab to hook up the airlines and visually inspect the kingpin (with a flashlight) to ensure the jaws are latched around the kingpin.
  • The final steps, remove the gladhand lock or unlock the airlock system. Raise the landing gear to full position and properly stow the handle. Remove wheel chocks and complete the walk around inspection.

Each of these steps is vital to ensure a safe trip. One of the most important steps is to check that the fifth wheel jaws successfully latched onto the kingpin, and the kingpin is not sitting on top of the jaws. This is the most common error, yet the most important part of this safety procedure. Now, let’s move on to uncoupling.


Once you’ve successfully completed a trip, now it’s time to unload and separate the tractor from the trailer. Let’s talk about how to do that safely.

  • First make sure the trailer is placed on level ground and if unstable (or not concrete), put additional boards or plates under the landing gear. Also, keep the unit inline for uncoupling and coupling.
  • Secondly, pull out the trailer parking brake button. Then, back the tractor gently against the trailer before pulling out the tractor parking brake. Exit the cab and put chocks between the duals.
  • Now lower the landing gear until the legs touch the ground. Verify that both gears are extended and in contact with the ground. Install the gladhand lock or lock the airlock system. Disconnect the air and the electric lines and complete the walk around inspection of the unit.
  • Lastly, release the fifth wheel locks and pull forward slowly, completing the uncoupling procedure.

Coupling and Uncoupling a tractor trailer is a common and essential procedure, so it never hurts for a little reminder of how to perform it correctly and most importantly, safely. Each week, a new safety tip will be posted, so stay tuned for more to come. Take a look at last week’s Safety Tip Sunday on completing a 360 Degree Walk Around Inspection here.

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