When we help a fleet experiencing connection management issues bring their trailers back into compliance, one of the first questions we get asked from the fleet managers and executives is, “how long will the kingpin last?” The answer depends on several important factors.  

As with most things, you must start at the beginning. Commercial trailers are manufactured by Original Equipment Manufacturers (OEMs) but that isn’t actually very accurate. They should really be called Original Equipment Assemblers. 

Many of the components, like kingpins, are manufactured by a Parts Manufacturer who supplies the OEM with the individual parts needed to assemble the trailer.

How Long Are Kingpins Designed to Last?

The SAE specification limits wear to a maximum of 1/8 inch with a 10-year expected lifespan. At that standard, the kingpin would average .0125” of wear a year.

From our experience, a fleet with brand new trailers will average .005-.010” of wear the first year. This means that kingpins should last anywhere from 12.5 to 25-years. Yet they often wear and need to be repaired in as little as 5-years.

What is causing the acceleration of wear?

Kingpins Wear Faster as Trailers Get Older

As connection stress increases from variables like the daily hours in service, types of loads, environmental conditions, road conditions, and the age\current wear of the connection components, we have seen fleets with wear rates more than .030” a year. As we stated earlier, at .030” of wear a year, the kingpin will exceed its threshold in less than 5-years.

There are three scenarios that cause kingpins to become out-of-service. All three scenarios can be successfully managed with a regular evaluation and maintenance program, but if these problems are ignored, it only accelerates the connection management issues.

Out-of-Service Kingpins Accelerate Wear

Once the kingpin has exceeded the manufacturer’s tolerance of .125” of wear, the kingpin should no longer be in service. Large variances in connection components, heavy loads, liquid transportation, daily connections and disconnections, environmental conditions, and road conditions, can all add stress to the connection components and increase the wear rate, thus reducing the expected service life.

Damaged Kingpins, Damage Kingpins

If a connection component is damaged, the connection will not function properly. This can cause an increase in the wear rate and/or damage the component it’s connected to depending on the type of damage.

Improper Installation Causes Major Problems

To ensure proper function a kingpin needs to be installed correctly. It is just as important to have proper alignment of the pin as it is to ensure that the structural mounting welds meet the OEM standards.

If a kingpin is not properly aligned, it can cause excessive wear and/or not couple correctly resulting in even more damage. If the kingpin is not secured to the OEM specifications, the pin can break loose from its welds and pull through the bolster plate, resulting in a catastrophic event where the trailer becomes detached during operation.

Repairing vs. Replacing the Kingpin

A repaired or replaced kingpin should wear at the same rate. When determining the best option, you must evaluate the overall condition of the equipment and decide if the repair cost will be sufficiently lower than the replacement cost to justify the repair.

In other words, if the trailer has lots of life left in it and you plan on using it for many years, the most cost-effective option is getting the kingpin repaired. Replacement of the kingpin is usually only advisable if the trailer needs structural repairs, and you are going to replace everything with new components.

When choosing the repair option, ensure that the company you choose to do the repair uses an engineered and proven method. Our refurbished kingpins are consistently measured against new equipment in the same conditions. Our wear rates are not only consistent with the new equipment, but through our connection management and pro-active repair service, we have helped fleets reduce their current wear rates. This extends the service life of the equipment and reduces the overall fleet connection stress and repair needs.

How to Make Kingpins Last Longer

It is very important that you don’t wait until you have trailers with kingpins that have wear that exceeds 1/8” or have become damaged. Address wear at a level that keeps the variance across the fleet manageable.

Perform annual inspections of the connection components and make sure kingpins are within the operational thresholds and fifth wheel jaws are adjusted and/or within tolerances. Finally, keep connection components properly lubricated and clear of dirt and debris.

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.

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?

Call us at 1-888-221-7774 or email us at repairs@kingpinspecialists.com.