In the past, a heavy-duty dump trailer simply needed to be tough enough to survive grueling construction sites and everyone was generally pretty pleased. But today, market demands, economic concerns, and changing fleet preferences dictate new designs and materials used in their construction.

New materials for light weight and durability

Aluminum was once a rarity in dump trailer designs, says Corey May, engineering manager for Manac, a heavy-duty trailer manufacturer with operations in both Canada and the U.S. But as manufacturers work to design lighter trailers that are still durable enough for heavy construction applications, aluminum in body panels is becoming more commonplace ­— as are other lighter-weight materials, he says.

“We are designing with a lot more exotic materials today,” May explains. “A new, high-strength structural steel called ‘Strenx’ is a common one, because it offers a thinner structural thickness to trailer walls and tailgates, which allows us to lighten the design overall. And an emphasis on lightweighting is where the majority of the trailer market is going today.”

May says Strenx allows Manac engineers to shave as much as 1,500 to 2,000 pounds off of a conventional dump trailer design while still maintaining strength characteristics similar to older, all-steel models. “We’re looking at a new Hardox AR500 product as well,” May notes. “Early reports are it is wear-resistant to the point that it enhances trailer durability by as much as 30%.”

When it comes to choosing the right material for trailers for your fleet, there are many factors beyond weight, including the application at hand, the materials being hauled, and your company’s operations.

Ralph LoPriore, director of fleet assets for Gary Merlino Construction/Stoneway Concrete, in Seattle, says, “Today, with Hardox 8-inch-thick trailer bodies, we have a material that is both super strong and lightweight enough to handle tough payloads,” he says. “I know they use a lot of aluminum dump bodies back east. But today, I can spec a steel trailer as light, or lighter, than some aluminum options. And I can still carry boulders or broken concrete thanks to the steel liners we put in the box.”

LoPriore also says steel bodies are easier for his technicians to maintain. “It’s hard to find technicians today, and even harder to find guys who can fabricate aluminum,” he says. “Steel welding equipment is commonplace on pretty much any construction site or fleet shop, and used all the time. But even if you can find a fabricator, aluminum is very hard to get clean enough to weld — particularly if you’re hauling asphalt. It does look great behind a truck. But I prefer steel bodies and make up the difference in weight by spec’ing lighter engines, transmissions and other components.”

That said, aluminum dump trailers remain popular in many vocational hauling applications. East Manufacturing has been using aluminum to build trailers since 1968, and touts the durability of it by noting that first trailer is still operational today.

“In today’s competitive environment, there is a strong emphasis in trimming weight wherever possible,” says Chris Cooler, dump product manager for East. “Finding the right weight vs. cost ratio for optimum payload remains a primary objective among owners. And aluminum dump trailers are a popular option for achieving those goals.”

Automation and sensors

Anytime you can confidently let technology remove a driver interface, you make it easier on the driver and help ensure optimal operation of the equipment. Cooler says that trend is affecting dump trailers, too. East is now offering automatically deployed lift axles and rear suspension dumps with auto-reinflate to help make drivers more efficient.

“With automatically deployed lift axles, the axle air-ride bag pressure is monitored, and the system raises the lift axle when the pressure falls below a preset level indicating the trailer is empty,” he says. “This saves on tire and brake wear, reducing operating costs. When the trailer is loaded, the pressure in the bags will rise above the preset level, and the system will automatically lower the axle.”

The rear suspension dump also has an auto-reinflate system, Cooler says. This feature allows the driver to flip a switch in the cab to exhaust the air in the rear axle suspension to improve cornering in tight areas such as parking lots, and is especially useful on longer trailers. The auto-reinflate feature automatically fills the rear suspension once the trailer speed rises above 10 mph. This system helps reduce tire wear and prevents the driver from accidentally leaving the air exhausted when he gets back on the road.

And more technology-driven features are likely on the way. Manac’s Corey believes that sensors that either alert the driver or automatically lower the dump body when a certain speed is exceeded will be common safety features in the near future.

“We’re also watching some interesting developments in Europe,” he adds. “Germany recently introduced new regulations requiring insulated trailers with sensors for asphalt haulers. The system is designed to ensure asphalt is put down at specific temperatures to ensure smoother road surfaces. If the load temperature drops below a designated point, the driver and fleet are alerted and the truck is routed back to the asphalt plant to get a fresh load of material. We believe it’s likely similar regulations and systems could come to North America in the future.”

Taking tarps to the next level

Tarping a loaded dump trailer is not a driver’s favorite job. But with a majority of states requiring tarps covering loose-material payloads, it has to be done.

Jeff Boyd, vice president of sales and marketing for tarping system manufacturer Aero Industries, says that’s why tarp suppliers are increasingly turning to electric- and semi-automated tarp deployment and retraction systems.

“A lot of fleets are tempted to put a cheap, manual system on their trailers just so they can check the ‘Compliant’ box,” Boyd says. “But we’re also seeing an increasing number of fleets that realize that they need to make it easier — and safer — for their drivers to cover loads and retract a tarp when they reach their destination. To put it simply, the easier it is for the driver, the more thorough the tarping job will be and the more secure the load will be.”

The main driver for this trend, Boyd says, is safety — both on the jobsite and on the road. The benefits of a tarping system are obvious at highway speeds, as is the importance of keeping material inside a dump body and off of John Q. Public’s minivan. “But we’re also talking to fleets who look at busy, crowded jobsites with rain and snow and mud — and they want their drivers inside the cabs of their trucks, where it’s safe, as much as possible,” Boyd says.

And in an age where a driver shortage is an ongoing fact of life for fleets, Boyd says many fleets want to avoid rotator cuff and other joint injuries that can occur from manually cranking tarps — as well as reduce the chance of slips, falls and other injuries.

The end result is an increasingly sophisticated array of electric- and automatic tarping systems, many of which can be operated right from the driver’s seat of a truck.

A box with wheels to haul materials is one of transportation’s earliest technologies. But it is obvious that the evolution of dump trailers is far from over.