How To: Grease a fifth wheel

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Unless you have a low- or no-lube model, fifth-wheel upkeep is all about grease.

Unless you have a low- or no-lube model, fifth-wheel upkeep is all about grease.

Insufficient lubrication can damage the top plate, locking mechanism and trailer kingpin and irregularly wear steer tires.

For this non-sliding, relatively simple Fontaine 6000-series model (pictured), Boyd Bros. Transportation’s shop uses a synthetic grease from Shell. Though maintenance procedures are similar for most models, manufacturers offer advice for different products:

Fontaine International

Jost International


Clean the fifth wheel.
Pressure wash to remove hardened grease above and below the top plate. Detail-clean with a putty knife or brush if desired, being careful not to damage moving parts. For extreme build-up, you may need to remove the top plate and clean the surface and channels with a solvent. Fontaine recommends fully degreasing every three months or 30,000 miles.

Apply grease.

  1. Using a lithium extreme-pressure grease, provide just enough lube for the trailer plate to spread it evenly across the surface.
    Leave the area around the center jaw free of grease.
  2. Boyd Bros.’ Hootie Cooper recommends stopping with a third of the top plate on the cab side ungreased. Too much grease results in a slippery catwalk or a polluting rig.
    w Hit all grease points to lube the interior moving parts, propping the plate up so it sits level.
  3. Fontaine recommends manipulating (from the locked position) the bumper at the center of the fifth wheel, pushing it off its seat with a pry bar, to trip the mechanism. Then separate the jaw and wedge with a large screwdriver and press grease between the two. If you haul often in extreme cold, a less viscous lube (diesel, motor oil, kerosene), sprayed on often, guards against premature hardening.
  4. Spread the lube by working the jaw open and closed with the locking key.