Just since last year, contractors and rental yards have been snapping up articulated dump trucks like pancakes at a fundraiser.
In 2004, North American sales jumped 30% to 40% over 2003, says Frank Manfredi of Manfredi & Associates, industry analysts. The surge was fueled by general economic growth and increased sales to rental yards, which purchase a large percentage of these big trucks.In terms of unit sales, manufacturers shipped 2,300 to 2,400 “artics” to North American buyers last year, says Caterpillar. The previous high sales figure was about 2,000 units, reached in 1998. Indeed, says Manfredi, all manufacturers have struggled to keep pace with demand since last year.
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PHOTO: Caterpillar |
To bring you the news of artics, we at Grading & Excavation Contractor visited ConExpo-Con/Agg, held in March in Las Vegas. “You’re seeing more and more contractors go to articulated trucks because they can work all year-round in the northern parts of the country,” says Caterpillar’s Michael J. Kennamann, market consultant for artics. “They’re being used for everything from shopping centers to overburden removal in quarries to road construction.”
At Volvo Construction Equipment North America, officials look for the boom in artics to continue through this year, says Buddy Goodman, product marketing manager for artics. He has observed new uses for artics firsthand. “I know of one contractor in California who used an artic to haul wet concrete to the paver,” Goodman says. “He had a fleet of A40 trucks.” Other unusual uses for Volvo artics include
- removing the body, mounting a fifth wheel, and using the artic to pull bottom-dump trailers;
- hauling lead ore in underground mines in Missouri;
- replacing the body with a large tree spade;
- replacing the body with a large solid waste container; and
- mounting a drill rig behind the tractor.
New Introductions
At ConExpo this year, Case introduced two new models of artics, the 335 and 340, with rated operating loads of 35 and 40 tons, respectively. Since the first two models were introduced at ConExpo three years ago, Case says it has sold “close to 100 units” in Florida.
Marketing Manager Dave Wolf points out that Case’s artics have no externally mounted dumping cylinders. Instead, the trucks have a wider rear frame, and the lift cylinders are mounted in-board, directly under the body.
That provides several advantages, says Wolf. The wider bed lowers the center of gravity for more stability, and the hydraulic cylinders don’t get damaged if and when the body rolls over. Moreover, the bed’s lift cylinders don’t get mud thrown onto them.
And Case designed the artic with the rear walking beam mounted to the bottom of the frame, not cantilevered off the side. The result is a stronger structure, Wolf says. The Case artic has limited slip axles throughout the machine; power automatically transfers from the wheels that are slipping to the wheels that are gripping.
Case’s artic models 325 and 330, the 25- and 30-ton units, have Cummins engines. The larger two models are powered by Iveco engines. All models have ZF automatic transmissions. You can shift the trucks manually, though; a button on the shift lever toggles you between automatic and manual. All trucks have six forward and three reverse gears.
Designed to be service-friendly, all Case artics have a Lincoln automatic greasing system that serves all lube points. All machines have a flip-forward hood and fenders that swing out 90 degrees and give you access to valves and transmission. On the larger two models, the cab tilts from right to left for access to the powertrain.
“On the 335 and 340 we have an LCD display backed up by a system that automatically checks all your fluid levels,” says Wolf. “Plus, you can retrieve maintenance and diagnostic information at that display in the cab. And it gives you a whole range of operating parameters, such as how many hours you spent in first gear, second gear, and so forth.”
The Case 335 and 340 models feature a dump brake. If you’re dumping the truck on an incline, you activate the dump brake and it will hold the truck in place. By shifting into forward, the dump brake is released. On the 330, the engine brake is standard, and a transmission retarder is optional. But the engine brake and transmission retarder are standard on the 335 and 340, Wolf says.
New Ejector Model
At ConExpo in March, Caterpillar introduced its 730 Ejector model. Instead of raising the bed to dump, the truck features a sliding ejector that pushes material out of the bed. Material can be spread and dumped on the go. Yes, the ejector adds about 6,000 pounds of weight to the truck and costs more, but Caterpillar’s Kennamann says that reduced cycle times enable an owner to pay back the cost premium in just two months’ use.
Ejecting a load without raising the body improves stability, so the truck can work on inclines and sideslopes and in soft underfoot conditions, Caterpillar says. The truck also does well in tunneling and underground locations and on sites where overhead obstacles, such as conveyors or power lines, would interfere with raised-bed dumping. The reinforced ejector body is made from high-yield, heat-treated steel. Its top rails incorporate the same steel used on the Cat 769D off-highway truck.
Caterpillar offers a full line of six artics, ranging from the Model 725 with 26 tons of capacity to the 740 Ejector with 42 tons of capacity. Kennamann says Caterpillar’s artics are heavier than the competition, which he claims is an advantage in tough conditions. “We have on-the-go differential locks, and we don’t get bogged down,” he asserts. “Our wet clutch differentials can be engaged and disengaged on the go.”
Caterpillar’s 730 Ejector truck features the Cat C11 engine with ACERT technology to meet the EPA’s Tier 3 emission standards. The engine produces 317 net horsepower and boasts mechanically actuated electronic unit injection. That system, together with air-to-air aftercooling and single wastegate turbocharging, provides low emissions and responsive performance.
The engine is matched to a six-speed electronically controlled transmission featuring an anti-hunt strategy and electronic clutch pressure control and controlled throttle shifting for smooth shifts and extended component life. The integral retarder offers high power density.
Low Operating Cost
Volvo says its trucks don’t have the lowest initial cost, but do provide a low ownership and operating cost. The current D series—which includes four units in the 25- to 40-ton class—was introduced starting in 2000. Volvo’s Goodman says the company consulted with customers when updating the line, and in addition to productivity and low operating cost, customers wanted improved serviceability.
“We pride ourselves that it’s easy to remove an engine or transmission to rebuild it, and easy to do daily maintenance,” says Goodman. “We electronically monitor fluid levels. You don’t have to pull dipsticks. When an operator starts up, the machine will tell you if a fluid level is low, or even if one is over-full.”
Access to daily maintenance points is a snap, Goodman points out. You don’t have to raise the hood to change oil or fuel filters—you just lower the front grille. Volvo provides a small removable hose that connects to the oil drain under the engine.
“We have a system called MATRIS—for Machine Analysis Tracking Information System,” says Goodman. “It’s available on all of our large equipment. We monitor all of the operating characteristics of the machine. You can download the operating history—time spent in each gear, the engine speed log over time, overspeed conditions, idle time versus time in gear, retarder use versus brake use, and much more.
“We still use the three-point suspension, but we improved the rubber spring in that system,” continues Goodman. “It’s larger in diameter and taller, and the shock absorbers were designed for the truck itself. They’re not just regular truck shocks.”
Manufacturers often build in retarders to save service brakes on articulated trucks. Volvo is no exception, and builds an inclinometer into its artics. Posted on the inside windshield is a decal that tells the operator what gear and speed to use to negotiate the hill he is descending using only the retarder and not the brakes.
Cooling fans automatically activate based on cooling demand, which is determined and controlled by the ECU, or electronic control unit. The cooling fans are not engine-driven, so they don’t rob the engine of power.
Power-to-Weight
Deere offers four artic models in the 25- to 40-ton range. All are made by Bell Equipment in South Africa. With horsepower ratings ranging from 265 net horsepower in the 250D to 413 net horsepower in the 400D, Deere’s four trucks boast power-to-weight ratios that are among the best in the industry, says Neville Paynter, product consultant.
“We try not to incorporate a lot of heavy metal just for heavy metal’s sake,” says Paynter. “You’ll see a lot of steel fabrication on our trucks as opposed to cast iron. The articulation joint, for example, is made of fabricated steel, not cast iron. The box is built of ribbed steel for better stress rigidity than a straight steel plate.”
Deere’s power-to-weight ratios keep the trucks going through the toughest conditions, Paynter says. And the approach angle on the truck’s front—30 degrees up from horizontal to the truck’s nose—is one of the sharpest in the industry, which prevents the operator from ground contact in uneven or hilly conditions.
Computerized controls make the Deere artics easy to operate—and nearly abuse-proof, says Paynter. When you switch on the differential lock, for example, it only activates for 30 seconds, then switches off. That way if the operator climbs onto a hard surface with the diff lock on, it doesn’t tear up the differential.
The Deere artics have five computer systems that all talk to each other. One controls the engine, one controls the transmission, one is a hydraulic controller, one controls the chassis, and one is an information center that collects data to give technicians access to operating and fault code information. “They all talk the CAN-BUS J1939 language,” says Paynter.
The fault code information is logged over time so a technician can tell how many times a particular problem has been happening. If the problem is with the operator, the technician can point that out.
Deere’s artics have what Paynter calls the best retardation system in the industry. Mounted on the output shaft of the transmission, the hydraulic retarder is fully automatic, which ensures strong, safe slowdowns. “You can operate this truck with very minimal use of the brakes,” says Paynter.
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PHOTO: KOMATSU |
Different Suspension
Komatsu offers three articulated trucks ranging from a 30-ton unit with 324 net horsepower to a 40-ton unit with 430 net horsepower. “No other truck has the trailing arm suspension,” says Steven J. Moore, product manager, trucks. “We’re the only people that pull the front axle, and that gives us a better ride. With the trailing arm suspension you get less shock transmitted to the operator’s seat.”
Ride and traction are improved by the hydro-pneumatic struts on both the front and back of Komatsu’s trucks, Moore says. “Again, you’ve got better control and better ride without a load,” he adds. “A Komatsu will stick to the ground better without a load, and it also gains better traction with a load.”
Moore emphasizes that Komatsu trucks are built exclusively with integrated Komatsu components backed by a heavy investment in research and development. “These are all 100% Komatsu trucks,” says Moore. “These are not kit trucks that are put together with an engine from one company and a transmission from another,” says Moore. “Komatsu has a huge commitment to R&D, understands the powertrain of these trucks, and it shows.”
Other notable features of Komatsu’s artics:
- A maintenance-free center-oscillating hitch
- Higher horsepower ratings than competitors
- A smooth belly under the truck for easy flow-through of mud
- A low center of gravity
Komatsu trucks also boast high top-end speeds, Moore says. Running on hard ground empty, the 35-ton truck can hit 35.4 mph; the 40-ton unit reaches 36.4 mph; and the 30-tonner clocks in at 36.7 mph.
Terex’s Five Models
Terex offers five models of articulated trucks, including units with rated payloads of 25 tons, 27.5 tons, 30.9 tons, 35 tons, and 40 tons. The company says the three smaller models all feature
- high-power, high-torque, emission-certified engines;
- automatic transmissions with manual overrides;
- automatic limited slip differentials in each axle; and
- a refined, quiet cab for greater operator comfort.
The 35- and 40-ton models have electronically managed, emission-certified engines, Terex says. And the trucks boast 6 by 6 all-wheel drive with efficient ground-following suspensions. Like the smaller models, the larger ones have automatic slip differentials.
So the choices are many. If you want a new artic this year, you’re well advised to order quickly. Manfredi says most of the larger manufacturers had sold their production for the year by mid-March.