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Best Bolster Plate Thickness

The Best Bolster Plate Thickness and Equipment for Your Fleet

Fleets often come to us with this complaint: “My trailers’ upper couplers are falling apart. Is there a different manufacturer or type of trailer that you would recommend we switch to?”

All equipment has its positives and negatives. With that in mind, there are some key aspects that we would suggest for you to see a longer service life out of your equipment.

What is the right bolster plate thickness for my trailers?

Trailer bolster plates come in a variety of thicknesses. 3/16”, 1/4”, 5/16”, and 3/8” are the most popular. The thicker the bolster plate, the more resilient the upper coupler is to daily use. If you have a married setup where you keep your tractor and trailer is attached the majority of the time and only disconnect and reconnect it on a monthly basis to keep it properly lubricated, then the bolster plate thickness would not be a concern from a wear perspective.

However, depending on the environment you work in, a thicker bolster plate may provide you a longer service life as the thinner plate could fail from corrosive conditions and warp as it ages. Manufacturers try to keep the overall weight down on the trailer so the load capacity can be maintained in the final assembly. By utilizing a thinner bolster plate, the trailer’s overall weight is reduced. 

Bolster Plate Thickness

We suggest a 5/16” or 3/8” thick bolster plate for drop and hook, doubles, liftgate, and high-use trailers. 

Will bolster plate coatings help extend the life of my trailers?

Many of our customers ask us what can be done to reduce the corrosion of the upper coupler assemblies. There are many different types of coatings that can be applied to help minimize the impact of corrosive agents like calcium chloride and road salt from deteriorating the coupling assembly.

From our experience in the field, the impacts of corrosion vary between the steel that was used in construction and the type of coatings that the assembly has been treated with. If the coating is more topical and does bond with the metal, moisture can get trapped under the coating, accelerating the corrosion process. 

We recommend an anticorrosive coating for all equipment. For the upper half of the United States and coastal regions galvanized upper coupler assemblies and landing gear may provide extended corrosion resistance.

Are Teflon plates and coatings worth it?

Technical advances and the search for a smoother process have given way to the Teflon no-grease fifth wheels and aftermarket Teflon plates as an alternative to grease. Although the Teflon aftermarket assemblies and newer Teflon fifth wheels do show some promising applications, there are several secondary impacts that we have noticed that cause us to question the overall benefit of their application.

As the friction on the glide path of the fifth wheel and the bolster plate can be reduced with the utilization of a Teflon plate, the tension and friction may be passed onto the connection components creating increased wear on the jaws and kingpin.

Also, aftermarket Teflon plates that are installed directly onto the bolster plate offset the contact zone of the kingpin to the jaws. The installed plate can additionally create a corrosion zone where moisture is trapped above the Teflon plate beneath the bolster plate.

Should I use grease on bolster plates?

Grease has been a proven lubricant that keeps the connection components working and provides a good moisture barrier. With all applications, you must maintain the proper amount to get the optimal results.  

If you do not keep the right amount of grease on the connection components, excessive friction and damage can occur. When operating in a rural area where heavy amounts of dirt come into contact with the equipment, routine replacement of the grease is advised so you do not create an abrasive environment.

We recommend that you inspect the grease on connection components monthly. If you are looking to add a Teflon application to your fleet, we suggest that you run a case study with that equipment and track your kingpin and bolster plate wear over a two-to-five-year period to ensure that the application does not indirectly create other issues. 

Time to Call the Kingpin Specialists

Without understanding the scope of the connection management issues affecting a fleet, it is impossible to quantify the real long-term costs. It is also difficult to make any meaningful progress in fixing the ongoing connection management issues.

Most in-house technicians do not have an engineered solution at their disposal, lack the experience and training required to repair kingpins effectively, and even misunderstand the relationship between the fifth wheel and kingpin. There is more to a kingpin than most people realize.

If you are responsible for fleet maintenance on commercial vehicles, why not take the first step and have Kingpin Specialists perform an inspection and report on the condition of your fleet?

Schedule a free fleet evaluation today.

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