Artics take on the steepest grades, deepest muck, and meanest moguls of America.
It's only sundown on the landfill, but you wouldn't know it from the buckets of rain falling in the near-dark. It feels like it's been raining like this for the last three years.
Underneath you are 30 tons of rumbling steel and rubber, and beneath that is landfill—everything from baby toys to errant construction-and-demolition materials in a leg-deep, swampy soup.
Just a couple of more runs across the yard, though, a couple of more tons of the stuff before the day's out. There'll be moguls, ankle-deep pockets of gunk, and 25% grades, but, hey, this is what articulated dump trucks (ADTs) are made for. From their first days in Europe to creating today's giants, their designers seem to have one concept in mind: Transport anything, anywhere.
Roots of a Giant
Volvo claims to have invented the ADT—also known as an artic—and be the first to mass-produce it. Known for its ability to turn or "articulate" the front cabin and tires, an artic is synonymous with dexterity. Couple it with six-wheel independent suspension and this off-road dump truck can roll over car-sized moguls that would bend a rigid-frame truck. With almost 40 years into the design, these dump trucks boast cargoes of more than 40 tons and turning radiuses as small as 13 feet.
Artics can crawl up 30% grades and reach top speeds of 61 miles per hour, all the while dealing with wet, soggy, off-road surfaces and low visibility.
There are artics in waterlogged landfills; steep, tight dam projects; miles of bumpy road construction; and even military operations. If you have something heavy to haul somewhere and the artic can't hack it, you might want to consider a helicopter.
One of Volvo's biggest artics, the A40D, is a 37-feet-long by 10-feet-wide behemoth that will carry nearly 82,000 pounds, or 20.9 cubic yards, of material and hit top speeds of 55 miles per hour. The drive train features differential locks, one longitudinal and three transverse, with a 100% lockup function that's operator-selectable on the move. That means more wheels stay on the ground and less spinout.
"Volvo articulated haulers can be found being loaded with overburden—clay, shot rock, gravel, sand, granite blocks, or just plain mud," Volvo's Mike Stec states. "Articulated haulers can run over solid obstacles with a height or depth of 16 inches, without causing damage to the machine. However, it is recommended that the height of solid obstacles should not exceed 1 foot. Ultimately, the operator really determines how fast he is willing to compromise his machine, body, and safety to haul-road conditions."
How often you want to repair your ADT will determine how far you can take it, Stec says.
"The key to being successful is uptime or availability. In applications where there are terrible job conditions such as mud, poor weather, or steep grade, Volvo articulated haulers outperform all competitors. No one offers a 10% dog-clutch differential lockup and therefore does not have the capability to travel as dominantly in submerged or deep-mud applications. Not to say that Volvo haulers cannot get stuck, but more operators all around the world would agree that the Volvo has the best traction control, which helps in winter with ice and snow to rainy and muddy job sites."
Stec also says Volvo's hitch area stands out.
"It's quite different than anyone else in the world. The fully automatic Volvo transmission provides a higher clearance distance under the hitch versus the competition, which provides a lower clearance distance under their hitch. Volvo's will not plow through mud due to the high hitch area, thus better negotiating in deep ruts while maintaining better fuel consumption. Also, the high hitch area will allow the Volvo to climb steep grades and continue forward at the top without encountering a 'high center' condition—whereas the competition can drag the hitch at the top or possibly stop due to the low clearance if the steep grade becomes quickly flat at the top."
John Deere promises a 40-ton payload on a body weighing just 63,603 pounds. Deere's 34-foot-long, 11-foot-wide 400D hits a max speed of 32 miles per hour using a Mercedes Benz 413-horsepower diesel engine. Absolutely essential to carrying a load off-road, 400D standards include an oscillation frame joint, plus hydraulic articulating steering, traction-control devices, high-flotation tires and an automatic transmission.
"The new Model D Series trucks are essentially a clean-sheet design over the previous generation. As with the previous model trucks, the basic design philosophy remains the same—focus on increased productivity, low operating costs, and increased uptime," says John Deere Product Marketing Manager Tim Averkamp.
"Depending on the application, it isn't uncommon for us to see anywhere from 10% to 30% lower fuel consumption and overall haul cycle times in the range of 5% to 10% better than the competition. Given today's fuel prices, customers are really taking note."
Caterpillar's heavy-hitting 740 and 740 Ejector models—both powered by a 3406E ATAAC engine delivering 415 horsepower—have a rated payload of 42 tons. The 740 will hold 30 cubic yards (30.2 cubic yards for the Ejector) of heaped material or 22.8 cubic yards (23.3 cubic yards) struck, and reach a top speed of 34.6 miles per hour.
Komatsu's competing in the 40-ton range with the HM400-1, a from-scratch design weighing 66,800 pounds. The HM400-1 also climbs near the 30-cubic-yard range for heaped material and includes a turning radius of about 28 feet.
Moxy offers the MT41, capable of payloads of up to 41 tons, and a total weight, loaded, of 73.5 tons. The MT41 holds up to 29.7 cubic yards of material and articulates up to 45 degrees in a turning radius of 13.5 feet.
"Moxy's free-swinging rear tandem bogie and the special articulation system offer excellent performance and the best possible ground contact in soft and difficult terrain," the company's Web site says. "The sloping rear frame, in combination with the track width, ensures a low center of gravity and best possible stability. One of the main highlights of the Moxy concept is the location of the turning ring in relation to the swing point. The turning ring is located in front of the swing point, which always ensures equal weight distribution to the front wheels in all situations, also during maximum turning."
But enough of the showroom. Out in a soggy Ohio landfill, Maintenance Manager Todd Perrine says four or five years of record rain have contributed to bad ground in the Midwest.
"We mostly use artics on steep grades. A lot of sites are wetter than normal, a lot of mud, but material still has to be spread."
Perrine says his employer, Kokosing Construction Company, currently runs about 25 units, mostly 35-ton Volvos, for everything from soggy landfills to huge dam and factory excavations to road repairs.
"We're out in southern Ohio on farm land in low-lying ground where it's wet and soggy," he says. "Almost too soggy for anything else."
Perrine says Ford is installing 200 steel-making ovens in the area, and the work requires digging down through foot after foot of peat to sand, where the ovens will be situated.
A $200 million West Virginia lock and dam project is also making for some tight squeezes for the ADTs, Perrine says. The project requires double shifts six days a week.
"We're running really hard on them, up the center of these steep grades and moguls."
And when a multimillion-dollar road construction project has a slip, Perrine says the artics are back out there.
"Talk about bad ground. We had a major slip on a project and we had to come back in and fill more material. It's too soft, just bad soil, wet, spongy, and swampy, just full of moisture," Perrine says. "You have to dig it all out and dig down to the good material, then you have to go find and haul material to build your fill back up."
Bill Minor, a heavy-equipment manager for Waste Management in Lombard, IL, says the company is running somewhere between 125 and 150 artics in a fleet of 7,000 pieces of heavy equipment spread out across the United States.
"In bad weather it's the only applicable vehicle to go out across a landfill with a [heavy] load. You try to do it with normal highway tractor-trailers and they fail pretty miserably. They get mired down, stuck," Minor says.
"Primarily we're in the landfill-waste-handling business and we use them to excavate dirt and haul daily cover for landfills. We do have one operation where we use special truck frames and haul containerized garbage from rail siding to the landfill working face, 20-foot containers that fit right on the back of an artic and haul it and dump it at the working face."
Greg Kittle, equipment manager for Ryan Incorporated Central, says the Janesville, WI,based company uses 60 artics with an emphasis on 40-ton Volvos and Terex ADTs, all from 1998 or later.
"They've been in some sloppy materials and wet materials that anything else would sink in," he says. "We use them as a specialty tool."
"I've seen them go ankle-deep in mud and they will certainly go deeper, though there's no guarantee that they won't get mired," Kittle notes. "It's a significant part of the hauling fleet. There's nothing quite like what they can do in muck, silt, clay, and other difficult positions."
Tom Kellerman, chief engineer with Clarkson Construction in Missouri, says artics have excelled in heavy highway construction and waterworks infrastructure like channels.
Artics have hauled 40-ton loads out of excavation projects running deeper than 100 feet, with maximum haul lengths of 1.5 miles, too far for a scraper team.
Kellerman says Clarkson's latest heavy road construction projects with artics started late July with $145 million in Kansas Department of Transportation contracts, some of the largest the state has ever had.
"We've had some situations where they've been going up 10% grades, probably 15% grades. I wouldn't dump them on that grade unless you want to turn them over." During channel work, he says, "We run them in pretty tight places where we have to back in, get loaded, and turn tight corners. We used them in limestone rock excavations in lieu of rigid frames starting probably five or six years ago. We felt the artics were better used in other situations handling both dirt and rock.
"The rough rock and gravel roads can beat up an artic just as much as a scraper," Kellerman says. "Any haul road that's not maintained well is going to be rough."
The need for versatility in ADTs' uses has pushed specialty items and system add-ons to fantastic levels. With equipment like ejector bodies that can spread fill like a backhoe and complex container-lifting modules, an artic can do nearly any job, says LeRoy Hagenbuch of Philippi-Hagenbuch Inc. of Peoria, IL.
Ejector bodies, which push debris out the back, mean fewer opportunities for the number-one hazard in artics: tipping. Raise the center of gravity with a bed full of debris and any slope magnifies the tip potential of the relatively light artic. Volvo cautions against even driving on certain grades, let alone dumping.
"Only in exceptional cases should a Volvo A35D be operated up or down grades steeper than 20% to 30%," says Volvo's Stec. "The absolute limit uphill is approximately 45%, and downhill the Volvo A35D can negotiate 50%, but other factors such as the available traction make it hazardous to work under such conditions. Only in exceptional cases should the machine be operated on lateral slopes of more than 15%. The maximum limit for the machine in travel on lateral slopes is 30%, but other factors such as roughness of the ground can cause the machine to tip over before this limit is reached."
Ejector bodies solve the problem of dumping on a dangerous grade.
"In unstable conditions you can dump. If you're in an underground area…you can dump despite the low clearance. With large fleets of ADTs on a construction job running 20 trucks a week, at least one will tip. The back end is over unstable ground and there are no rigid connections to the frame, nothing stabilizing it to the other parts, plus a little, lightweight frame," says Hagenbuch.
"The rear eject is really a safety issue. The last thing you want to try and do is spread with a rear body up. It's just a stability issue."
Author's Bio: David Downs is a writer based in San Francisco.