How To Hook a Trailer Onto Your Rig

Trailer Hookup

Successfully hooking up a trailer on the first try is an essential skill for all semi-truck drivers. Being able to efficiently complete this task will make your work day flow more smoothly and assist in meeting deadlines. Our team at White’s International Trucks strives to be a great resource for all drivers, so we’ve put together a list of steps you should follow to properly hook up a trailer.

Anatomy of Trailer Hookups

Before we can break down how to safely hook up the trailer, it’s important to know the different parts you’ll be working with and common terminology.

  • Landing gear – retractable legs that support the front of the trailer when it is not coupled to a semi-truck.
  • Kingpin – vertical steel pin that protrudes from the bottom front of the semi-trailer.
  • Fifth-wheel – horseshoe shaped coupling device found on the rear of the semi-truck.
  • Air line – flexible hose tubing that conveys pressurized air to operate the air brake system.
  • Air supply valve – located on the dashboard; octagon shaped red button that controls release and application of trailer spring brakes.
  • Hand valve – also known as trolley valve or Johnson bar; works the trailer brakes and should only be used for testing.
  • Tug test – test performed after coupling the fifth-wheel and kingpin; engages the trailer brakes while pulling forward slightly to determine if the trailer is properly hooked to the truck.

How to Couple the Trailer and Semi

  1. To hook up the trailer you will first need to back the truck up, stopping just as the fifth-wheel touches the trailer. Apply the parking brakes and exit the truck to evaluate the height of the trailer. You should always double check that the trailer height matches your rig, otherwise you will experience issues later on, such as the kingpin dropping over the front of the fifth-wheel. 
  2. Confirm that the handle is out and the locking cogs are in the locked position. Continue to back the truck underneath the trailer. Check that the handle is now in position, there is no space between the fifth-wheel and trailer, and the jaws are locked behind the kingpin. 
  3. Wind up the landing gear a few inches to conduct a tug test. This will ensure the fifth-wheel and kingpin are locked into place. If it hasn’t been attached correctly, the trailer will fall onto its landing gear and you can start back at step one. 
  4. Once you confirm the trailer is secured, wind the landing gear up all the way. Attach the air lines and electrical cord. 
  5. Get back into the cab and roll down your windows to listen for leaks and proper brake function. Release the truck’s parking brakes. Then, conduct another tug test, with the trailer parking brakes still engaged, to make sure the trailer does not move. Push in the trailer supply valve. 
  6. Actuate the hand valve a few times and listen for air being released from the trailer.This check will indicate if the trailer service brakes are working correctly. Move ahead a few feet while activating the hand valve again to see if the trailer service brakes will in fact bring the unit to a stop independently from the truck.

In some circumstances, it may be necessary to perform a pre-trip inspection of the trailer itself. This is especially true for new trailers. 

We hope this guide has been helpful to you! With seven locations throughout North Carolina, our team works hard to be accessible and helpful for any driving needs. We offer lease, rentals, service, and more!