Fifth Wheel Maintenance Tips

Tips on the Care and Maintenance of your Fifth Wheel
Let's cut to the chase...what's a tractor without a fifth wheel? A chassis that can't do its work! Luckily, fifth wheels are almost maintenance-free, but there are a few critical points to keeping them in good shape. The Kenworth Customer Service Center offers a wealth of advice. Along with this, we're sharing great information from the staff at Fontaine, Holland Hitch, and Jost.

First and foremost, think safety when you are inspecting your fifth wheel. There are several things that a driver can do:

1. Keep the fifth wheel lubricated.
2. Make sure that it is still connecting properly to the trailer.
3. Verify that a sliding fifth wheel is locking properly.

All of these can--and should--be done without touching the fifth wheel yourself.

The folks at Holland Hitch add the following recommendation before you start your inspection: have the entire fifth wheel system thoroughly steam-cleaned. Clean the top plate, brackets, slide plate, mounting angles, and fasteners. Next, so that you can take a good look at the fifth wheel, use a trouble light or flashlight for your visual inspection. Plan to take ten or fifteen minutes for this project.

Guide to Fifth Wheel Care & Maintenance

Test Those Jaws

This is the safest way to examine your fifth wheel's jaws and make sure they aren't worn out...it's a two-person test, so ask someone to help you out for a moment.

• Latch the fifth wheel onto the trailer as usual.
• Set the trailer brakes.
• Have your assistant stand where he or she can see the fifth wheel.
• Move the chassis back and forth slightly.
• Have your assistant watch to see if the plate moves relative to the trailer.

If the plate does move, the jaws are probably worn. Head into the nearest Truck Enterprises dealership to have it checked by our professionals. If the jaws are indeed worn, your fifth wheel may be one that can be rebuilt rather than replaced, so you'll want to ask about that option.

Do You Need to Adjust Your Fifth Wheel?

It is possible to have fifth wheels adjusted, but it's not typically necessary. In talking with a representative of Jost, we learned that this is not something that usually needs to be done with their products, and in fact, frequent adjustments can cause premature wearing of the locking mechanism. Jost states that they have many fifth wheels in service with over 400,000 miles on them that have not needed adjustment. Fontaine told us that if it's needed, their fifth wheels are easy to adjust--they can even be adjusted while the trailer is coupled to the fifth wheel if the situation calls for it. Holland Hitch provides manuals, as do the others, for those occasions when a fifth wheel needs adjusting. If you suspect this is the case, it should be checked out by trained staff.

Dented Top Plates--What to Do?

Sometimes fifth wheels take a hit when a driver is coupling the trailer and the chassis. Unfortunately, this can affect the jaws themselves or your ability to lock them. When there's damage like this, it's wise to have it checked out. We recommend caution in this situation if someone offers to rebuild the fifth wheel--it may not be the right thing to do. The fifth wheel is a part that is on the DOT's checklist with good reason.

Watch for Loose Pins

Some fifth wheel designs feature two pins on top of the plate. These are the pivot pins that jaws hinge on. If they are loose in the plate, it's time to replace the fifth wheel. You can perform a visual inspection for this by looking for cracks in the grease that you have applied to the part. If the pins are tight, you don't typically see those cracks. If you do see them, take your chassis in to the shop.

Look for Cracks

While cracks in the grease can be a sign of loose pins, it is also possible to have actual cracks in the fifth wheel components, welds, and mounting angles that are hidden by that same grease. This is why steam cleaning is a help. Articulate the top plate forward and rearward, and look underneath the top plate. Check out the fixed front lock in the top plate, too. While you're looking for cracks, make sure that there aren't any missing parts. Also, if you suspect a part has been modified, take it in to your Kenworth dealership for a professional inspection. Fifth wheels are a critical safety component and shouldn't have any modifications.

Caught That Handle on Something?

The Kenworth Customer Center takes calls on this situation fairly frequently, so if you've done it, you're not alone! In this case, you need to have a trained service person look it over--this is another case where you don't want to start investigating without thinking and place your hand in harm's way.

Air Slides and Air Release Locks Should be Checked

If your fifth wheel is equipped with either of these, check the condition of the air lines, energize the system, and check for leaks.

New Fifth Wheel Tough to Slide?

It gets easier to slide as the fifth wheel is used. If you are having trouble with it, however, you may want to ask your dealer to buff and polish it to eliminate any metal surfaces that may be a bit rough. Greasing the fifth wheel may help also. Over time, simple use will smooth the rough spots as well.

Don't Wear Out Your Top Plate

Lay a 48-inch straight edge across the top surface of the fifth wheel. The top plate should be flat within .06 inch. Also, check for wear in the "dish," or recessed area, in the middle of the top plate. The dish isn't designed to carry a load or make contact with the trailer upper coupler. If you see that it is getting worn, the trailer needs repair and will cause fifth wheel problems if it hasn't already.

To Grease or Not to Grease

Keeping the fifth wheel well-lubed in the jaws is key to making it easy to release. This is true in most cases, but not all. There are some designs and materials that shouldn't be lubed. Let's go over those...

• Have a plate with a Teflon disk? Don't lube it--essentially, the material is the lubricant.
• Does your fifth wheel have slider jaws? Don't grease these, it just causes them to hold dirt. The only wear point on these is the air cylinder, and you don't want to cause any problems there.
• Finally, use a grease gun! There's no need to put a hand into a fifth wheel.

How Often Should You Lube Your Fifth Wheel?

Thoughts on this vary, but generally speaking, if you hook and unhook trailers frequently, you'll want to keep it lubed. It seems like you have more of a chance of getting dirt into that fifth wheel in this situation than you do if you are mainly doing long haul work.

Who Should Maintain or Replace Your Fifth Wheel?

The representatives of the fifth wheel companies felt that it is basic enough that fleet shops could do it themselves, and so the question probably comes down to a matter of time. At Kenworth PremierCare, we'd like to remind you that we can do this work for you if it frees up time for you to handle the other service work you have stacking up! We also welcome independent owner/operators--we've got the experience and skills to keep your operation running smoothly. Your Kenworth PremierCare Parts & Service dealer carries fifth wheels and fifth wheel parts in the Fontaine, Holland Hitch, and Jost lines and regularly does professional inspections, adjustments, repairs and replacement of fifth wheels.
Remember, if you run into problems with your fifth wheel while you're on the road, call the Truck Enterprises location neareast you and we can help you arrange for service or repairs.