Machine Matters – August 2009

Articulated dump trucks with 30- to 40-metric-ton hauling ratings prove massive muscle can be efficient and effective.

In a market where many machines now sit idle, articulated dump trucks in the 30- to 40-metric-ton payload range can often find new lives as not just rock and dirt haulers, but also as fuel, water or lube trucks, or pipe and timber haulers.

Several manufacturers offer the option to buy a bare ADT chassis and outfit it with the body of your choice. “First consider the intended application and type of load the truck will carry, then optimize the body for the truck chassis,” says Steve Moore, product manager, motor graders and trucks, Komatsu North America.

Body choices include those mentioned above as well as waste and ejector bodies, and hook lifts or roll off units. “In the last four to five years, we’ve seen more contractors putting large water tanks on our artics for dust control,” says Mitch Blake, brand marketing manager, Case. Because ADT tires offer high flotation even in soft ground, some contractors have also chosen lube service chassis for remote maintenance.

Massive movers
New uses aside, ADTs continue to be best suited for hauling substantial loads of dirt or debris from messy, hard-to-access highway, mining and large residential construction sites. “In many cases, these applications require an all terrain vehicle to reach work areas and having a larger payload makes for a more efficient operation,” says Blaine Pressley, product specialist for articulated haulers, Volvo Construction Equipment.

Most important, an ADT should haul loads effectively and safely in the shortest amount of time possible.

To do this, consider several things: the machines needed to load the truck; the type and amount of material to be moved; jobsite conditions; total cycle distance and production requirements.

“Failure to match your hauler to the type of material being moved is one of the largest causes for lower productivity,” says Jay Alexander, commercial/product manager, Caterpillar. Take into account the material’s size, content, moisture and thickness. And as Alexander points out, an ADT won’t always be your one-size-fits-all hauling solution when working with numerous types of materials. Instead, you may need to enlist several haulers, such as tractors equipped with scrapers.

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To improve cycle times, consider an ADT with automated controls such as John Deere’s Driveline Assist function, which restricts dump body height to limit time wasted raising the bed once materials have already exited. “Driveline Assist automatically puts the truck in neutral, sets the parking brake and increases engine speed once the dump lever is engaged to raise the body and dump materials,” says John Chesterman, product marketing manager, ADTs, John Deere.

As for jobsite conditions, ADTs in the 30- to 40-metric-ton class feature six-wheel drive to effortlessly run over soft and/or wet soils and rocks. While tires play a large role in easing the ride for operators, so do the truck’s suspension, transmission and traction controls.

For a smoother haul over rough terrain, Volvo’s A35E and A40E incorporate a maintenance-free suspension with the operator centered in the cab over the axle. “With the A35E and A40E’s full hydraulic suspension, we’ve seen as much as a 32 percent increase in productivity tests in rough terrain, as compared to our standard suspension,” Pressley says.

On its ADTs, Komatsu offers a standard hydropneumatic suspension, which uses nitrogen oil in both the front and rear suspension systems, hydropneumatic struts acting as shock absorbers and a trailing arm pivot point to enable the truck to glide over bumps.

Cat coupled its three-point front suspension with a walking beam arrangement on the trailer unit working in conjunction with the axles and center hitch to provide additional stability and ride quality, even while operating at high speeds. “The front suspension offers +/- 6 degrees of axle oscillation along with Cat’s off-highway technology – which is built into the hydraulic/nitrogen suspension ride strut – to give operators a smooth ride when encountering rough underfoot conditions,” says Bob Todd, senior product specialist for articulated trucks, Caterpillar.

On Case’s B Series ADTs, the independent front suspension has both vertical and oscillating movement, while the rear suspension includes dual, cast-steel beams secured directly under the rear frame for long-term operation.

Energy boost
ADTs may be known for their massive load hauling capabilities at relatively quick speeds, but don’t let the power trip fool you. Today’s engine technology has transformed these trucks from excessive fuel consumers to fuel conscious workhorses.

For instance, Komatsu’s ADTs include an engine power mode selection system so drivers can select the most appropriate work mode depending on conditions. Power mode suits jobsites where the truck sees high resistance, and economy mode serves well for light work on flat ground. According to the company, this system can improve fuel economy by up to 10 percent when used correctly.

“We also recently optimized our transmission control, where Komatsu’s K-Atomics – or electronics supplied to the transmission – work in tune with the engine so the transmission shifts more smoothly,” Moore adds.

Volvo attributes its engines’ reduced fuel consumption to providing high torque at low rpms. “On our ADTs, the Volvo 6-by-4-mode drives only the front and mid axles, so the rear axle is free rolling, reducing drive line wear, fuel consumption and tire wear,” Pressley explains. “Of course, if needed, you can put the machine into six-wheel drive with the push of a button.”

With Caterpillar’s 730 ADT, the Cat C11 ACERT engine optimizes the air-to-air aftercooling system to regulate temperature while operating with tight tolerance combustion chamber components to maximize fuel efficiency and minimize emissions. “Cat’s C15 ACERT – on the 735 – has a 7-percent power increase as well as the air-to-air cooling benefits, and now has up to seven forward gears and two reverse gears, made available through Cat’s TH38 transmission for better fuel economy and smoother shifting,” Todd says. This update replaces the previous eight forward/one reverse gearing option.

Haul monitors
Although additional hauling options and fuel-efficient engines represent profitable possibilities, it means nothing to your bottom line unless you can monitor daily progress. Manufacturers have begun to make this easier by equipping ADTs with the latest machine management software so you and your operators can assess hauling tasks from start to finish.

Komatsu’s HM350-2 and HM400-2 ADTs come standard with Komtrax, a fleet monitoring program that sends machine operating information to a secure website using wireless technology. Komtrax relays location, hour meter, cautions and maintenance alerts to the website, where users can access the information. In turn, the program helps increase machine availability, reduce theft and allow for remote diagnosis of any issues the machine may have.

“Komtrax also allows operators to monitor fuel usage,” Moore says. “For example, if you have an ADT running through the mud all day long and notice terrible fuel usage, you can return to the jobsite the next day and opt for a different route to get better fuel economy.”
Similar programs are available, including Caterpillar’s Product Link/Equipment Manager software, Case’s GlobalTracs Fleet Management and more. Ask your dealer about these programs, as some do not come standard.