When Mark Roush thinks about finding ways to make trailers cost less, yet last longer, he doesn't limit his focus to composite materials and new manufacturing processes. In fact, some of the things he's keeping an eye on seem quite mundane. In the context of trailer building, however, they're almost radical: glue, for example.
“The future to me is using glue — referred to more technically as adhesives — to manufacture trailers,” says Roush, director of engineering for Vanguard National Trailer Corp., Monon, IN.
“Glue doesn't rust and it holds just as well on brackets as rivets do — even better in some cases,” he says. “What people don't realize is that the glue we're talking about has a sheer strength of 2,000 psi, whereas your average rivet has a maximum sheer strength of 1,200 psi. So you're using something that theoretically has a much stronger bonding force between the sidewalls of a trailer and its structure, not less.”
Also, by using glue, trailers can be manufactured faster and cheaper, without compromising strength and durability. “One of the most costly parts of manufacturing a trailer is the man-hours it takes to rivet the sidewall to the frame, and every rivet represents a metal-on-metal contact point where rust and corrosion can develop over time,” Roush says. “So if you go to glue, you're looking at using one single sheet of aluminum sidewall without rivets. You're taking a tremendous amount of hours out of the production process, yet giving the trailer more durability in terms of corrosion prevention.”
When it come s to designing trailers, Roush is someone who's used to thinking outside the box — and on his toes. He's spent his engineering career designing or tweaking a wide variety of trailer models, from flatbeds at now-defunct Dorsey Trailer to refrigerated and insulated units for Kidron.
Finding ways to make trailers less expensive yet more durable has been a challenge wherever he's worked. And Vanguard is no exception, where the focus is now on finding ways to better protect cargo and minimize corrosion while reducing weight and maintaining durability.
“Look at trailer scuff linings,” says Roush. “Most [trailer makers] use plywood to reduce weight, yet plywood can lead to a variety of maintenance issues, especially if it gets wet,” he explains. “Many manufacturers are using recycled ‘milk jug’ plastic to offer better protection without the worry of wood rot, but that plastic is heavier than plywood and can shrink more rapidly than the sidewall in cold weather, creating a lot of noise and turning a trailer into what's called a ‘rattle van.’”
At Vanguard, Roush is now working with a thermoplastic blend called “DiamondPly” that uses a mix of plastic and fiberglass to form a cross-web pattern that is rigid, durable and resistance to weather-related shrinkage, yet far lighter than recycled plastic, saving over 250 lb. per trailer.
Roush cautions, however, that there is a limit to how far you go in reducing weight. “When you are trying to save weight, you usually have to give up something — either take something out of the structure, which can compromise the integrity of the unit, or change the design,” he explains.
In terms of corrosion, Roush says that reducing the number of weld points on the trailer is one way to boost trailer life. “Welds create a weak point where corrosion can gain a foothold,” he says. Consequently, Vanguard pre-assembles as many components as possible. You can maximize corrosion protection by taking the pieces of the trailer with the most weld points and galvanize the entire section. “But if you can go to adhesives, you totally eliminate that problem.”
Trailer flooring is another conundrum of sorts for trailer engineers because the need for durability often conflicts with maintenance, cost and weight issues. Roush says that this is one area where thinking outside the box still can't beat the benefits of tried and true methods.
“When you look at plastic flooring, it gets very slick when wet, which isn't good for forklifts or humans when you are loading cargo. But [giving] plastic flooring some texture to improve traction make it too expensive,” he says. “All- aluminum flooring gets you where you want to be in terms of long life, strength and light weight, but it's just too expensive. So right now, oak wood flooring remains the most cost-effective option since it's the one wood species that fights the fungus and microbes that cause rot. [Flooring] is just one of those challenges we have to keep working on.”