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Encapsulated upper coupler could extend trailer life, reduce rollovers

GREENSBURG, Ind. -- A rollover involving one of his tanker trucks has prompted an Indiana-based entrepreneur to design an upper coupler that promises to improve safety and extend trailer life.

GREENSBURG, Ind. — A rollover involving one of his tanker trucks has prompted an Indiana-based entrepreneur to design an upper coupler that promises to improve safety and extend trailer life.

Elvin Knollman runs a small tanker fleet out of Greensburg, Ind., hauling fuel throughout the Midwest. In 2008, one of his tractor-trailers was involved in a low-speed rollover, which was initially blamed on his driver. Witnesses said the truck was travelling slowly when it flipped over, prompting Knollman to question the initial conclusion that driver error was to blame.

The trailer had recently been inspected and was thought to be in good repair. However, Knollman’s investigation revealed the rollover was caused by a faulty upper coupler, which was badly corroded on the inside. Eventually, the shop that conducted the inspection was forced to pay the majority of the clean-up costs, but having seen the damage that can result from a corroded upper coupler, Knollman set to work developing a solution.

The result is his encapsulated upper coupler, marketed by his new company LGM Coupler.

“Because the upper coupler is sitting under the trailer, people don’t know how to inspect it,” Knollman said in a recent interview with “Here in the northern states, we have such a corrosion issue with magnesium chloride and calcium chloride; the life-expectancy of an upper coupler isn’t very long. I’m in the tanker industry, so naturally I wanted to figure out how to fix this issue.”

Generally, upper couplers are stitch-welded and have drainage holes that allow corrosive de-icing agents to enter. Grease can then seal the holes, trapping the corrosive chemicals inside the coupler. This causes the upper coupler to rust from the inside out, and the damage can’t be seen through a visual inspection.

Knollman’s design features air passages between the channels, which can be inspected using air pressure. He shoots 15 psi of air through a valve up into the framework and then inspects it for leaks. When no air leaks are detected, he then encapsulates the upper coupler to prevent chemicals from getting inside. But first, he injects glycerin or anti-freeze to ensure condensation doesn’t form. Some of Knollman’s designs include a cover plate that fits over top the entire upper coupler. This area is also filled with lubricant so that the exterior of the upper coupler itself is protected from corrosion.

Knollman began working on the design of his encapsulated upper coupler about four years ago.

“Then the economy tanked, and that really threw things back,” he said. “But in a way, it made things better, because I’ve been able to make a better design that’s lighter weight.”

Knollman has since developed a universal upper coupler that can fit any slot hole design, for compatibility with a wide range of trailer manufacturers. He has reduced his product line from 19 models down to six, making it more feasible for trailer shops to carry the product.

One model features an integrated replaceable king pin, “so you have a lot less cost when king pins wear out.”

When ordered on a new tanker trailer, the encapsulated upper coupler with replaceable king pin could last up to 30 years, whereas today’s designs often need to be replaced after seven to 10 years of use, Knollman pointed out.

“This is going to change the industry,” he said. “And it should eventually, I hope, change the way that manufacturers build trailers – not only tankers, but flatbeds and vans.”

While Knollman has just begun marketing his encapsulated upper coupler, there are already about 200 units in the field today. Interest from trailer manufacturers and dealers has been high, but Knollman also sees enormous potential in the aftermarket, particularly with tanker trailers, which have a longer life-cycle than vans and flatdecks. One major courier company is looking at the system as a way to potentially extend the life of its van trailers beyond their current 13-year replacement cycle, with many of those trailers scrapped due to upper coupler failure.

“It’s an expensive thing to replace, so a lot of times they just scrap the trailer,” Knollman said.

Knollman’s biggest breakthrough came late last year, when tank manufacturer The Mueller Company announced it was making the LGM encapsulated upper coupler standard equipment on its new line of trailers. Mueller has traditionally been a manufacturer of stainless steel tanks, and recently expanded to include tank trailer manufacturing. Mueller said it feels the LGM upper coupler gives it “a leg up on our competition, by incorporating a component that adds a new dimension in inspection and corrosion control to the upper coupler.”

For all the potential the encapsulated upper coupler has for reducing accidents and extending trailer life, it’s not an expensive system. The cost is about US$150 for a standard OEM model or $400 for the fully encapsulated design with replaceable king pin. Knollman acknowledges it adds some weight to the trailer, due to the cover plate and lubricant. The weight increase in van trailers is limited to the weight of the lubricant, since the trailer floor eliminates the need for the cover plate.

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3 Comments » for Encapsulated upper coupler could extend trailer life, reduce rollovers
  1. Steve Brown says:

    way to go that sounds like something all companies should get interested in, rollovers especially for tankers are very costly and usually preventable, anything that can help to minimize rollovers should be investigated.

  2. Donald J Kaleta says:

    In reference to the above article to “REDUCE ROLLOVERS” I’ve submitted the following information. Please search http://WWW.DEFORMABLEKINGPIN.COM for my complete research submission to the Transportation Research Board, it’s suppressed rejection for publication,and my responce. There is a common sence resolve to save Destruction, Harm & Deaths when Trailers, of commercial vehicles are IMMINENT to ROLLOVER. Ask yourself a question. If a Tractor cannot mitigate (stop) an IMMINENT rollover of it’s attached Trailer, WHY continue to force the Tractor to participate in the rollover that will, Harm and at times Kill, it’s occupants–Men Women & Children?
    Donald J Kaleta 2/21/2013

  3. JP says:

    Interresting article

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