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How Clean, Inspect And Lubricate The Fifth Wheel

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There is probably no better time to clean, inspect and lubricate the fifth wheel coupling on your truck than right after winter ends. The fifth wheel is subject to lots of abuse from not only hooking and unhooking trailers, but it can be beat up by the winter, too. Cold temperatures, ice and various road contaminants can find their way into the fifth wheel's mechanisms and cause mischief with moving parts. Corrosion and abrasion from sand and rusting caused by salt are just two problems that can occur. That is why you should spend time taking a closer look at your fifth wheel and performing a cleaning and lubricating session. Below is what you will need and how to take care of the maintenance:

What you will need

  • Penetrating oil in gallon can size

  • Pump-up sprayer

  • Large putty knife

  • Long-handled plastic-bristled brush

  • Rags or disposable shop towels

  • Synthetic all-purpose grease (NLGI #2) tube and gun

  • Five-gallon bucket

  • Flashlight

Step-by-step procedure

1. Remove old grease and contaminants - The first step in getting the fifth wheel ready for another year of service is to remove any grease and contaminants that have accumulated. You won't be able to adequately assess the functioning of the moving parts, such as the release handle, jaws and locks, if they are full of gunk.

To clean these components, begin by scraping away as much gunk as possible with a large putty knife. Wipe the blade of the knife clean on the rim of a five-gallon bucket. Don't forget to work underneath the top plate where offending materials can accumulate.

After you have removed as much as possible with the putty knife, apply a thin coating of a penetrating lubricant on all dirty surfaces using a pump-up, handheld sprayer. If there are hard-to-reach areas with accumulations, then adjust the spray nozzle to a stream-setting and "blast" the material out of the nooks and crannies. Permit the penetrating lubricant to soak for a few minutes in order to dissolve grease and loosen up other contaminants, then wipe it away using old rags or heavy-duty paper shop towels.

If necessary to gain access, you can also use a long-handled brush with stiff bristles to work areas around springs and in narrow spaces between moving parts. Spray down these areas with more penetrating lubricant to give them a final cleaning, then wipe away the excess.

2. Inspect the fifth wheel for functioning and corrosion – Once you have cleaned up the fifth wheel, you can take a closer look to make sure all components are working well and that there are no signs of corrosion. You may need to use a flashlight to obtain the best view if lighting conditions are poor.

When inspecting, check the functioning of the release handle by pulling it several times. Observe the handle's spring to be sure it isn't corroded or weak. In addition, inspect the jaws and locks to be sure they can open and close properly; if they bind or stick, then check further for obstructions inside the mechanism. If you cannot locate any obvious problems, but the functioning of the fifth wheel seems limited, then you will need to have a qualified mechanic take a closer look.

3. Apply new lubricant to the fifth wheel – After you have cleaned and inspected the fifth wheel, the last step is to apply new lubricant. You will use a general-purpose, synthetic grease with an NLGI #2 rating for the top plate, inner surfaces of the jaws and locks, release spring, and fittings.

Begin by applying a line of grease to the top plate, then smear it in a thin coating over the entire top of the metal surface. Add an extra coating over the bottom two-thirds of the plate; this grease will be pushed up toward the top of the plate when hooking up your first trailer. Avoid using too much grease, as it will only make a mess and entrap future abrasive or corrosive materials.

Next, apply a thin layer of grease to the inside of the jaws and locks of the fifth wheel, and also add grease to the spring on the release handle. Push the grease down in between the coils of the spring to ensure it lubricates them during compression. Again, be sure to remove any excess amount of grease with a rag or towel. If the fifth wheel contains any grease fittings, add grease to them as appropriate using a gun.

For help repairing or cleaning a particularly stubborn fifth wheel, contact a company like Godfrey Brake Service & Supply.