A well-maintained fifth wheel is a driver’s link to safety.

If your fifth wheel is not working the way it is supposed to, you’ve got trouble. Proper coupling, as well as regular maintenance of the fifth wheel, can save you time, money and hassle.

Perhaps the most critical aspect of the fifth wheel begins when the driver approaches the trailer to hook up. Greg Laarman, vice president of engineering for Jost International, says this is an important operation because many drivers may not realize that it’s possible for a fifth wheel to couple in a non-positive manner (known as a “high hitch”), which is a very dangerous situation.

Coupling right
The first step in coupling to a trailer is to get the trailer at the right height. The fifth wheel’s top plate and pivot are designed to guarantee proper coupling, but they can only do their job if the trailer is at the right height. This is why trailer landing gear has the low range for raising and lowering the trailer nose even when loaded.

1. Back the tractor up to the trailer so the fifth wheel just touches the nose of the trailer. Make sure the tractor is properly lined up – the tractor and trailer are centered with one another.

2. Get out of the cab and observe the position of the nose of the trailer upper coupler where it contacts the top plate of the fifth wheel. The trailer must touch the top plate 4-6 inches behind the pivot point of the top plate. The top plate must remain angled down at the rear, too. And the trailer must be positioned so it will have to lift up to hitch. If the trailer is too high, pull the tractor forward and use the landing gear to lower the trailer, then back the tractor back underneath. The nose of the upper coupler needs to be high enough to ride on the ramps on the top plate. If too low, raise the trailer with the landing gear, back the tractor under the trailer and recheck the height. Be sure also that the kingpin is lined up with the gap between the two top plate ramps.
3. Once the height is correct, back the tractor under the trailer. You must be able to feel the resistance as the trailer lifts. You’ll also hear the top plate flatten out and come to rest flat against the upper coupler. Stop the tractor at this point. Then gently feather the clutch and back just until the kingpin seats and comes to rest against the forward end of the gap between the top plate ramps.
4. While raising the landing gear, crouch down and observe the top plate where the upper coupler rests on it. There must be no visible gap between the top plate and upper coupler.
5. After raising the landing gear and stowing the crank, get under the trailer and look at the position of the kingpin. It must be securely trapped in the locks in the fifth wheel. Also, on a Jost fifth wheel, check the release handle to make sure it is fully retracted and in the lower notch. On Holland fifth wheels, check that the nut and washer on the front of the fifth wheel rest tightly against the top plate. Other fifth wheels have a similar procedure for checking that the mechanism is properly locked. Check your owner’s manual for details.
6. Most drivers know the importance of leaving trailer brakes on and pulling forward with the tractor to test the fifth wheel and make sure it’s properly hitched. Make sure to do this to double check that you have coupled correctly.

Cleaning and lubrication
As with almost every working part of the rig, proper lube of the fifth wheel will help keep it operating as it was designed and help prevent premature parts failure. It will even help the handling of the rig.