Why So Many Bad Kingpins

Why Do I Have So Many Bad Kingpins?

“I have 100 commercial trailers and 35 of them have bad kingpins, why do I have so many bad kingpins?”

Fleet evaluations show that 25% to 35% of commercial trailers have a kingpin that is worn or damaged and needs to be immediately repaired. In this article, you will learn about the most common reasons why fleets have so many bad kingpins and what to do about it.

Why Do Kingpins Wear and Get Damaged?

Connection management is what we work on with fleets to keep the wear rate down so they can not only get the most service life out of the trailers but also keep the fleet operating within the MFG operational threshold. That being said, dry vans on dedicated long routes with limited daily uncoupling and recoupling actions can operate for 20-years or more without wearing out a kingpin. The more you stress the connection components and the higher the wear variances are across the fleet, can drive the wear rate higher. Drop and hook, multiple stops, uneven roads, unlubricated components, and damaged equipment are all variables that increase the stress to the connection components.

On a new refrigerated fleet with new fifth wheels, we typically would see a very low wear rate, around .006″-.010″ a year, depending on the application. As the fleet ages and the connection components wear, the wear rate will slowly increase. This can be reduced by regular fifth wheel maintenance but that only addresses half of the connection components wear issue. Over time, even with regular scheduled fifth wheel maintenance, the wear rate can increase to a rate that is just not manageable by fifth wheel maintenance alone. The kingpin and upper couplers will begin to wear beyond the operational limits faster, and even if they are repaired or replaced at the operational limit, the fleet’s current high wear rate and large variance in the connection components will continue to impact the new and repaired equipment.  This perpetual cycle leads to a situation in which repair needs exceed the projected budget and the fleet requires a major overhaul to get back to a stable wear rate that can be managed by routine maintenance.

Common Myths About Connection Management

“I have never changed a kingpin.”

This is a statement we hear many fleet maintenance managers and technicians make. They have convinced themselves that what they aren’t doing, doesn’t need to be done.

Time after time we run into fleets that are under the impression that the kingpin doesn’t need maintenance. Although low connection stress applications will have a lower wear rate, all connection components will have wear. If you are not tracking your wear equipment, issues can impact the entire fleet before they are identified.

“I repaired all my bad kingpins, I should be good.”

False connection components will continue to wear. Repairing the bad kingpin addresses the result of the equipment wear. To solve the cause of high wear, yearly maintenance and tracking is needed to keep the wear rate low and equipment operating safely. 

How to Fix a Fleets Kingpin Problem

Our first priority is to get the fleet back into compliance (repair all red level trailers) so we limit any out of service issues and safety aspects with the trailers. Once we have the fleet in compliance, we work with the fleet managers to establish a maintenance plan so that we can address the trailers proactively. By addressing the trailers proactively, we reduce variance between the components and drive the wear rate back down to a lower, more manageable rate.  Listed below is a breakdown of refurbishments needed to keep the fleet compliant when addressing the trailers at the manufacturer threshold. As discussed earlier, by completing repairs at the end of their service life we are only addressing the results of the wear issue, not the cause.

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

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