With its horseshoe shape and prominent placement, the fifth wheel may be one of the most easily discernable parts on a truck. Its maintenance also may seem simple: Keep it clean and keep it greased.
The fifth wheel may not have an abundance of parts, but the parts that do comprise it suffer severe strain as they work together to perform their main function of uniting trailer and tractor. But this connection is far from static. Often the trailer needs to move independently of the tractor and this is where proper fifth wheel lubrication comes into play.
“The fifth wheel is the key component that allows the trailer to pivot easily back and forth when the truck is in motion and aids in making turns. Obviously, when the driver makes a turn, the trailer needs to follow, and a properly lubricated fifth wheel helps make this possible,” said John Geyer, industrial marketing specialist, Chevron Products Company.
The connection between the fifth wheel and the tractor is a metal-to-metal mating. If there was no lubrication between these two surfaces, incredible levels of friction would develop.
“Without lubricant, you would create higher degrees of friction, which, in turn, would lead to increased metal-to-metal wear between the trailer plate and fifth wheel,” said Geyer.
But it’s not just the flat fifth wheel plate that needs to be lubricated. Close attention also must be paid to the device’s other moving parts.
According to Dan Arcy, technical marketing manager, Shell Lubricants, “there actually are several areas that need to be lubricated on the fifth wheel. You mainly look at the top of the fifth wheel, but there are other components of the fifth wheel where it actually slides. The locking and unlocking mechanism also requires lubrication.”
If close attention is not paid to fifth wheel lubrication, costly damage will occur. “An improperly lubricated fifth wheel can lead to a binding condition or high wear of the connecting points between the trailer pinion and fifth wheel jaws,” cautioned Mark Betner, heavy-duty lubricant manager, CITGO Lubricants.
