Fifth wheels are seldom coupled with thoughts about regular maintenance plans. Still, these devices, built by such companies as Holland Hitch, ASF (American Steel Foundries) and Fontaine, do require regular care.

Key to any fifth wheel maintenance plan is the lubrication that will ensure releases work easily and that wear is limited. Here, the recommendations of manufacturers should always be followed – particularly with respect to the type of grease used for the jaws, lock pins and the yoke assembly or the sliding jaw.

This time of year, as the remnants of snow and ice begin to melt away, it’s important to clean the equipment before you begin. You can use a hi-pressure washer or steam cleaner to remove caked-on and dirty grease, particularly on the top surface of the fifth wheel plate and around the jaw.

When it comes time to actually apply the grease, it’s important to remember that fifth wheels typically have grease fittings at several locations, and not just on the plate itself. Some models have components that require no lube at all.

Some are equipped with polyurethane bracket shoes that require no lubrication at the interface of the bracket trunnion. In addition, some wheels employ either a non-abrasive urethane or Teflon-type thick plate attached to or molded to a steel backing plate on the top of the plate, negating any need for a regular application of grease on the top plate. Other options include newly introduced fifth-wheel inset plastic rubbing pads. If you own one of these varieties, you only require lubrication in the lock/kingpin area.

With fifth wheels that are not equipped with such a top plate, ensure that there’s a heavy coating of grease on the top surface, applied directly or through the grease fittings on the underside of the plate. Conventional grease with a lithium base is commonly recommended.

Keep in mind, however, that excess grease on fifth wheel components simply attracts dust and dirt and can form an undesirable lapping compound between moving parts (not to mention the extra cost associated with using too much grease). And when warmer weather comes, the melting and dripping grease will ooze everywhere.

When it comes to other maintenance, avoid pounding on any air release pins with a hammer while compressed air is being applied, otherwise a rusted pin that breaks free can drive the head of the hammer back towards you.

If a slider is sticking, avoid the practice of using soap to free the device. The soap will wash away the slider’s lube and eventually lead to problems such as corrosion.

Why is all this important? If you don’t clean and lubricate the fifth wheel plate and bearings within the mounting surfaces, you’ll face a rough ride or steering problems.

When it comes to visual inspections, watch the condition of jaws and locks, looking for signs of wear. If the locks loosen by no more than approximately 1/8 inch (3 mm), the play will become excessive and lead to “trailer chucking” – the back and forward movement caused when a load is applied and released.

If you do find a problem, take heart that typical fifth wheel rebuild kits are relatively inexpensive, costing anywhere from $80 to $250.

Also, be sure to check and discard the top plate if you find any cracks. And test the locking mechanism by locking and unlocking the fifth wheel several times, to ensure that it works as easily as it should.

If you’re responsible for an array of fifth wheels, you might want to order the testing tools designed to check locking mechanisms. The locks are typically adjusted by closing them around a special two-inch (51-mm) diameter plug that’s also available in a test kit from the OEM. Close inspection of the trailer kingpin can also be accomplished by using a special OEM-supplied template to check that it sits square, and that its dimensions are correct.

Next month: Troubleshooting fifth wheel problems. n

– Bob Brady is the president of HiTech Consulting in Burnaby, B.C.