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East flatbeds have hollow-core side rails, which provide fully enclosed conduits for wiring.

Although not obvious to the casual observer, today’s trailers are better designed, are built from modern materials, and offer new technologies designed to increase productivity and reduce maintenance.

Better by design
Although modern trailers look similar to those of yesteryear, state-of-the-art engineering has made them stronger and lighter. “What has changed to improve structural integrity is a more accurate method in determining where stress loads are the highest,” says Mark Roush, director of engineering for Vanguard National Trailer Corp. “This has been accomplished primarily with better design tools that can analyze the properties of the various materials used in the construction process. By replacing heavier components with equally strong, lighter-weight materials and adding extra strength in areas that need beefing up, trailer designers have been able to build significantly better trailers to carry specific loads without fatiguing elements of the design.”

“We’ve continued to reduce trailer weight by utilizing lighter-weight, higher-strength materials in practically every area of the trailer,” says Rod Ehrlich, chief technology officer for Wabash National. “The use for composite floors is another way to reduce trailer weight and increase floor load capacity.”

But how much weight can be taken out before durability is affected? “We’ve seen some trailer-suspension component cracking,” says Darry Stuart, president of Quickway Transportation, based in Wrentham, Mass. “Too much weight has been taken out of some areas and, in those cases, we have lightweight and durability boxing with each other.”

Another trend in van trailers is composite panels used as side, front and rear door materials. These have gained popularity in freight vans, providing maximum interior width and length, and a smooth, snag-free interior, says Vanguard’s Roush. “For long-haul, truckload operations, composite-plate trailers, such as the Vanguard VXP, have become the standard.”

According to Charles Cole, manager of technical sales and product training for Utility Trailer Manufacturing, the 4000 D-X thin-wall dry vans have a 101-inch-wide interior, and logistic posts at least every 24 inches for more cargo-shoring versatility.

“Thin-wall trailer designs continue to gain popularity because they provide fleets with added interior width and cube capacity,” says Wabash’s Ehrlich. “As you would expect, more interior width allows for more freight per trailer and better margins for fleets. Our DuraPlate trailer allows fleets to ‘pinwheel’ pallets and increase cargo capacity.” In addition, “The DuraPlate HD utilizes a unique, heavy-duty base plate that eliminates the need for an interior scuff liner (a high maintenance item). It also provides 22 inches of lower sidewall protection, where it’s estimated that 90 percent of trailer damage occurs.”

“Durability and maintenance have become major issues for fleets,” agrees Great Dane’s vice president of dealer sales, Chris Hammond, “so trailer companies have either moved away from, or engineered, alternatives to traditional plywood liners.” One such alternative is Great Dane’s PunctureGuard, a thermoplastic liner and scuff material that increases strength and puncture resistance without adding weight.

According to John Sullivan, vice president of maintenance and purchasing for Performance Transportation Services, based in Wayne, Mich., newer materials like composite panels are better all around. “They enlarge the ‘freight envelope,’ they’re tougher, and they cost less to repair,” he says. He’s also a fan of spec’ing anti-snag roof bows, because they “prevent damage to cargo as it’s being loaded.”

When it comes to flatbeds, taking out weight must be done carefully, with attention to areas that shouldn’t be compromised. “Trailers don’t usually break from being overloaded,” says Hank Prochazka, vice president of sales for Fontaine Fleet. “They break from being racked, side-to-side. With our Phantom design, we’ve developed a thicker, 12-inch-wide bottom flange – which is extruded in one piece with the main beam, eliminating the flange-to-beam weld – that provides five times the side-to-side strength of previous designs.”

“Many of the trailer manufacturers have been set with the duty of reducing trailer weight due to increased tractor weights caused by increased truck options and EPA requirements,” says Lenny Miller, director of dealer development for Benson International. “This has caused most trailer manufacturers to look at better designs to meet today’s load requirements.”

For example, “Steel dumps have greatly improved over the years with the use of AR400 and AR450 materials,” Miller continues, “reducing the thickness of steel and saving considerable weight without compromising the integrity of the trailer.”

According to Charlie Wells, director of dump trailer products and dealer development for East Manufacturing, aluminum trailer manufacturers have the advantage in that today’s aluminum alloys offer the durability of high tensile-strength steel at less than half the weight. Much of the design innovation has centered on the main load bearing part of a flatbed – the main beam.

Moreover, he adds, the most significant improvement in aluminum dump trailers has been the introduction of the smooth-sided trailer body, which is rapidly replacing the traditional sheet-and-post trailer body style.

Smooth sidewalls are built of double-wall aluminum extrusions with internal ribs connecting the inner and outer skins. These ribs generally mean about eight times the support provided by external posts, typically positioned every 25 inches. This, says Wells, minimizes deformation between the ribs, a major cause of wear and subsequent failure.

Corralling corrosion
Savvy trailer purchasers are willing to spend more for the protection of certain areas of the trailer that are damaged prematurely by harsh road chemicals or repeated exposure to the elements, says Vanguard’s Roush. Protection options include: hot-dipped, galvanized rear frames, impact guards and other rear components that come in contact with docks that scrape away paint, causing rust; hot-dipped, galvanized understructures, landing gear bracing and front components that are impacted during coupling and uncoupling; and coating crossmembers with materials such as wax that is self-healing following impact with road debris.

One of the hottest topics for fleets that operate in the northern states is corrosion, agrees East’s Wells. “Chemicals like liquid magnesium chloride used to fight snow and ice on the roadways are so corrosive that they can even put a stain on stainless steel.”

While aluminum is not affected as badly as steel, aluminum trailer manufacturers are improving their products’ resistance to corrosive elements. Hollow-core side rails, for example, provide fully enclosed conduits for wiring, and manufacturers are using sealed lamps and wiring harnesses to keep out the elements. And some manufacturers, like East, are developing ways to replace traditional steel components, such as suspension hangers, with rust-free aluminum designs. In addition, new anti-corrosive coatings are being used on steel bolts, and shim-like isolator devices are being used to shroud steel parts with stainless steel.

Meanwhile, Utility has added a stainless steel door frame and buckplate on its thin-wall dry vans, integrated the rear threshold to eliminate rotting wood beneath, and has provided corrosion protection with the use of paraffin-based, soft coatings and paints.

No doubt, trailer manufacturers are taking more precautions against corrosion, but the war is far from over. “Corrosion is still getting worse,” says Quickway’s Stuart. “We’re seeing better coatings and, just driving on the highway, you can see a lot more stainless and galvanized steel. But the use of newer, corrosive ice-melting chemicals is spreading faster than the industry can keep up.”

Corrosion continues to be a major topic at meetings of the Technology and Maintenance Council and, hopefully, “we’ll find the answer,” says Stuart.

The right stuff
In addition to trailer structures being stronger, lighter and more resistant to corrosion, trailer manufacturers agree that running gear and ancillary items also have improved in recent years. “From a manufacturer’s viewpoint, we like the way trailer suspensions are being supplied,” says Fontaine’s Prochazka. That’s because they’re easier to install as a module, with no fuss. “They come all buttoned-up,” he says.

Performance Transportation’s Sullivan also likes the buttoned-up approach. “If you get the whole package – axles, suspensions, brakes, wheel ends, etc. – from one supplier, you’ll get a better price and a better warranty.”

As relatively recent improvements, Utility’s Cole cites better wheel seals and bearings, lighter wheel-end components, better wiring harnesses and LED lighting, which lasts indefinitely and are becoming more and more affordable. Also, adds Prochazka, “We think onboard tire inflation systems are a great safety feature.”

“Keeping tires properly inflated is the single most critical factor for getting the most out of tires,” says Great Dane’s Hammond. “By maintaining the proper inflation pressure, tires last longer and are safer.”

No argument from Sullivan, who specs onboard tire inflation systems, and notes that, “They’re good for fuel economy and tire wear – we’ve seen a payback in less than six months.”

In sum, it would be fair to say that today’s trailers, if properly spec’d, are more productive, require less maintenance, are safer and can last longer. But, “Know what you’re buying,” advises Quickway’s Stuart. “Visit the factory, do a ‘paper’ pilot inspection, and make sure you’re getting what will do the job. And, make sure you have a good, solid trailer and tire maintenance program. Without that, all the gadgets in the world won’t do you any good.”