Articulated haulers and rigid haulers are very different machines.
Contractors need to make sure they match the truck to the job, taking into consideration what kind of material they’re hauling, how much of it there is, and how far they’re hauling it.
“There’s not a market trucks don’t fit into,” claims Jimmy Slavens, general manager, Chicago division, for Roland Machinery. “Scrap, aggregate, waste, construction, demolition—they’re everywhere.”
Seemingly so. Thanks to a strong construction market and increased mining in the early part of this decade, demand was high for rigid dump trucks (RDTs) and articulated dump trucks (ADTs). Sales and production levels were up; so, too, were imports and exports. Now, due to the economy and tire shortages, Yengst Associates, a market research and consulting company, reports that the demand has peaked and sales of both have tapered off.
Tell that to Slavens. Roland, a family-owned Komatsu distributor, does $200 million annually, its core business the sale and rental of construction equipment. The company fleet of 30 dump trucks used to be rented primarily for big dirt jobs, but the trend is changing, he says. Now they’re used for site prep, sewer and water jobs, and dirt jobs—and they’re often onsite two to three years, so more companies are buying.
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Photo: International
Typical settings for rigid dump trucks include hard rock quarries. |
Rent or buy, most companies are turning to ADTs to fulfill their needs. What’s more, he says, they’re turning to Komatsu. One customer, Bluff City Materials, started with six trucks from another manufacturer, but has replaced them all with Komatsu and bought two more last May. The decision was based on productivity, Slavens says: how they load, capacity, haul speed, and how they travel on grade.
“Many jobs don’t require rigid,” Slavens says. He cites high prices, high capacity, and the need for good roads as reasons why. “An artic can adapt.” The particular needs depend on the industry. Sideboards may be added for extra capacity when hauling metal pellets, for example. “You can add different size tires, tailgates … They have heated bodies if you’re working in the winter.”
In addition to productivity, he says it’s important to consider reliability and dealer support. “Seventy-five percent of our business is Komatsu,” Slavens estimates. “It has the best product line we’ve ever had.”
Articulated Versus Rigid
Komatsu offers both a full line of RDTs and an extensive line of ADTs. “Construction companies can’t usually afford to have both, so most opt for the flexibility of the artic,” explains Steve Moore, product marketing manager, motor graders and trucks, Komatsu America Corp., Rolling Meadows, IL. “You need to determine your needs and look at the application in order to choose which works best for you.”
A prime consideration is environment. Will you be on-road or off-road? Generally speaking, the rigid truck does not perform well in grades above 10%, while the ADT is capable of managing grades of 30% or more, even in muddy or rough conditions. RDTs are intended for use on very well-maintained haul roads with minimal grades.
According to Blaine Pressley, with Volvo Construction Equipment Hauler Loader Business Line in Asheville, NC, “articulated haulers are designed for use in basically all terrains. They can operate very efficiently on smoother roads; however, they are best suited for rough-terrain applications where roads are very rough or don’t exist at all. The rotating hitch, along with six-wheel-drive and independent rear axles, gives the trucks the ability to traverse some of the roughest terrain imaginable.”
Because of their rotating hitch between cab and body, they can tackle rough terrain without frame twist and with less tire wear than the conventional steering design used on the RDT.
Other key considerations are the size of the job and production requirements. Payload size is very different for the two types of haulers. “Rigid haulers usually have higher load capacities than articulated haulers,” Pressley says. Capacity ranges from 40 tons to 380 tons, while maximum capacity for the ADT, according to Moore, is 43 tons.
The two types of trucks are simply “designed for two different needs,” states Melissa Gauger, with International Truck & Engine in Warrenville, IL. These two needs, she says, are “dedicated off-highway and on-off-highway.”
ADTs are very adaptable and can easily work in hostile conditions where other equipment can’t go, because they can get to a job site and back without being disassembled. All-wheel-drive and suspension designed to keep all wheels on the ground in rough terrain means they operate in off-road conditions and are therefore better suited to short-term projects such as new construction.
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Photo: John Deere
Articulated haulers are designed for use in practically all terrains. |
“Articulated trucks are ideal for hauling materials on undeveloped construction sites, such as residential and commercial building starts, road and bridge construction, mines, quarries, and landfills,” says Ken Emmett, product manager for Terex Construction Americas in Moline, IA. They’re easier to move around, are smaller, and don’t require a permit to move. The initial purchase price is usually less.
The choice should also be based on how long the job will last and how much is being hauled. Rigid trucks are bigger and can haul more per trip, thereby reducing operating costs and making them appropriate for longer-term projects at mines and quarries where better haul roads are usually built—roads sometimes pioneered by an ADT. In addition, they have a longer life because they’re less complicated. According to Caterpillar, RDTs are more in demand in large mining and quarrying applications, where high-volume production is the focus. Conversely, ADTs are better suited to smaller operations, especially where sites have steep grades.
Vive la Difference
The two types of dump trucks are “designed drastically differently,” emphasizes Bill Nadelhoffer, product marketing manager of trucks for Komatsu, “to capitalize on different applications better.”
Standard configuration of an RDT, he explains, is rear-wheel drive on four wheels, so it is capable of achieving higher speeds, although it requires prepared roads. Conversely, the ADT goes anywhere, albeit more slowly, with its six-wheel-drive permitting it to travel in rough terrain through worse conditions where roads don’t even exist.
Typical markets for the RDT include quarries—specifically, limestone, hard rock, and marble. Nadelhoffer refers to a Komatsu customer in Georgia who mines kaolin, used in toothpaste and paint. “He needs high production out of the quarry to feed the hopper,” indicating that speed is imperative. “The rigid is a specialized animal, good for high-production quarries.”
The ADT, on the other hand, is versatile because of its design: six-wheel drive, oscillation of axles, and articulation. ADTs are often used at landfills and for road-building projects since they can “run up to the axle in mud.” The artic is available in 30-, 35- and 40-ton, while the rigid offers capacity up to 260 tons.
Because of the different work environments, the two types have a lifetime difference of 2:1. “The rigid lasts longer,” Moore clarifies. When it comes to choosing a type and brand of dump truck, “know your application.”
Beneficial features offered by the Komatsu ADT, Moore says, include a tailgate, used to retain material such as rock and slurry; welded-in steel liners for hard rock; an optional plastic/polymer liner that nothing sticks to; and body heat—the exhaust gases run through the body to keep material from freezing.
Other assets include improved visibility; a smooth ride, thanks to the nitrogen-over-oil suspension; more horsepower; and electronics that protect and monitor the equipment remotely. “Komatsu is the only company with wet disc brakes, oil suspension, the operator on the left side, low-maintenance and a lube-free center hinge on the artic truck,” Moore states. That translates into better performance and reliability.
Extreme (Artic) Conditions
In addition to job requirements, site requirements also influence the choice of truck. ADTs are well suited to all-weather applications and can work year-round, according to Caterpillar. They perform in harsh environments with soft underfoot and where haul roads are poorly installed or badly maintained, such as equatorial jungles in Third World countries, or in areas with rugged, steep, mountainous terrain. Or the hard rock tar sands in Edmonton, AB.
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Photo: Terex
Contemporary truck designs focus on the dual qualities of productivity and power. |
“We operate in the worst, most extreme conditions,” claims Brian Weeks, director of equipment for Ledcor CMI Ltd. “We need the best equipment.” The construction company, specializing in mining and industrial applications, purchased several 100-ton ADTs from various manufacturers. Because of a shortage, “we had to get them from everywhere,” but it’s the 31-ton Caterpillar 730S and the 43.5-ton 740S he relies on at construction sites and for the development of pits.
That’s typical, according to Cat. ADTs are very versatile units, often the first machines on the job site and major players in preparing the infrastructure for the introduction of larger machines. All-wheel-drive and articulation make them capable of working in the hostile conditions where wet, frozen, and underdeveloped job sites are common. In some areas, contractors are replacing rigid trucks and scrapers with articulated trucks, which are being used in more applications because of their adaptability and capability for handling harder digging conditions in Canada’s frozen, rugged terrain. One key is their ability to maneuver where other machines can’t go, thanks to a center hitch.
The center hitch is the fundamental differentiator between and ADT and an RDT. ADTs are fully articulated with 45 degrees of articulation, which provides maneuverability in tight confines. “Its turning radius is 10 feet sharper than the rigid dump,” Weeks exclaims. When his crews are performing underground utility work, they have very limited room, so the machine’s width and turning radius are important.
“Width is an Issue,” Weeks confirms. “They have to get around in close quarters with a tight turning radius.” He says the articulated truck is 12 feet, 6 inches wide; the 40-ton rigid truck is 3 feet, 2 inches wider. “If you haul on the road with public traffic, you’re better off with the artic; it doesn’t bother traffic as much. Even with road width restrictions, you don’t need pullover roads. We can haul an artic on the highway without a pilot truck. That saves money. It’s also easier to move from one site to another.” While being moved, it rides better because of the central pivot point, Weeks believes. The three-point front suspension system and center hitch provide a comfortable ride for the operator when negotiating rough areas.
In addition, the standard Cat differential distributes torque to each wheel evenly for increased maneuverability over bumpy terrain and tight turns. When closed, the x-axle diffs enable 100% drive-train lockup for maximum traction. That’s also important to Weeks, who doesn’t want his trucks to sink in when digging trenches to pump water. “You can sink a 100-ton in the muskeg,” he notes. With the Cat ADTs, Ledcor can put the fishbone-like pattern trenches closer, with holes to drain the bog land. Weeks says they’re also good for spreading material, explaining that the decomposing vegetation must be replaced on the muskeg.
ADTs are less durable than RDTs, but offer an excellent alternative in bad weather and poor working conditions. Weeks knows they work well in all conditions, through four seasons. “They give us the opportunity to go in winter to prepare for spring without destroying the muskeg.” With heated boxes, crews can “drain ponds before the ducks get in,” dig drainage ditches in the winter and pump in the spring. “We don’t need graders on haul roads. After preparing the roads, we can bring in 100-ton and 150-ton Cat trucks.”
Weeks is so pleased with the Caterpillar ADTs, he plans on building a lube service with them. “Since we’re 24 hours from the States and service locations, we’re going to build a lube-service body for the 740 and 750ts.”
Efficiency
Dave Strayer, assistant operations manager for Lycoming County Resource Management Services in Montgomery, PA, doesn’t perform official studies because, as a government entity, “we’re stuck with low bid,” but he believes his Volvo ADTs provide better fuel efficiency, which can come into the bigger picture with bidding, he hedges.
The county-owned landfill and recycling center services six counties, processing 1,200 tons per day in addition to special projects, such as excavating for buildings. The facility’s 500 acres sit on federal land separated by Route 15, which trucks must cross … with proper permits. That’s one of the reasons Strayer opted for ADTs.
Others include the full suspension that provides a better ride. “The guys work 10-hour days, sometimes 12- to 14-hour days,” explains Strayer, who formerly worked as an operator. Ride becomes important.” Handling is also important for long hours spent in the cab. “They do a lot of backing over slopes 2:1 or steeper so they can dump right on the slope. Everyone preferred Volvo’s ride and handling.”
Lycoming owns five Volvo 40-ton articulated haul trucks and recently added a 25-ton truck. “We used the A25 to do slope work and repairs on gas lines because it’s versatile and maneuvers well.” Strayer’s plan is to rotate trucks every three years, so one of the five is currently for sale, thanks to the recent purchase of a new FS series that the company tested on site for a week.
The Full Suspension Articulated Hauler is a Volvo innovation: the industry’s first actively controlled ride-suspension system. Pressley explains: “These machines incorporate fully hydraulic suspension that provides an extremely smooth ride along with cross-flow hydraulic functionality that provides an antiroll functionality. The cylinders are filled with oil as needed to keep the body and frame in line with the axles.” He says the new system contributes to increased productivity of up to 32%.
Another Volvo exclusive is the “hydro-mechanical self-compensating” steering system. During operation of the machine, the system provides constant feedback about the activity of the dump body, automatically adjusting for positional changes to assist steering, especially during high-speed hauling. The operator does not have to constantly adjust the steering wheel to keep the rear frame in line with the cab.
Other factors contributing to high productivity and fuel efficiency include Volvo’s exclusive 6x4 drive mode. It reduces tire and drive-train wear by allowing the rear axle and tires to turn freely in standard operating mode. For better traction, longitudinal and transversal lock can be activated while the truck is in motion, thanks to an exclusive locking dog-clutch system.
Volvo’s recently introduced E model haulers include improvements such as higher hitch clearance for better stability when loaded; higher horsepower and torque and increased load capacity without sacrifice in fuel efficiency; intelligent shifting technology that can skip gears when needed; five-stage exhaust-pressure brake from the engine along with the company’s standard all-wheel brakes.
Despite having a lot of equipment, Strayer reports few issues: “some front axles, wiring harness issues, but not a lot of repeat issues. We can’t complain about our haul trucks.” In fact, he says, “We want Volvo to do a compactor!”
Size Matters
ADTs are not new, but in the last 20 years, they’ve gained a lot of popularity, claims John Chesterman, product-marketing manager for ADTs with John Deere in Moline, IL. “They’re flexible. They can haul everything from shot rock to processed aggregate, and they can move dirt in conditions where scrapers would get stuck: wet, muddy, soup. They’re used at quarries to strip overburden off; the rigid can’t get out in soft and sloppy conditions. They’re now the preferred method of mass-excavation earthmoving. People used to use self-propelled scrapers, but they’re expensive and you need dozers to help load.”
Sizes range from the 25 short-ton to the 40-ton, although Chesterman has noticed a shift toward the larger truck. However, he says the 25-ton is good in “really soft ground conditions” and the 30-ton with low-profile tires has the “lowest ground pressure in the industry for soft ground like in Florida.
“The heavier it weighs, the more it will sink in mud,” he continues. Sinking isn’t the only hurdle to scale. “You want the power to carry loads, but a heavy truck hurts in fuel economy and travel.” One of the benefits of a John Deere, he adds, is that they have the lightest empty weight. Instead of large cast iron, they feature a steel-fabricated axle housing. Rib-style bins provide strength but reduce weight.
Chesterman lists other notable John Deere characteristics: fuel-efficient engine and lockup torque converter for better fuel consumption; heated seats for driver comfort; an automatic exhaust-valve brake and transmission retarder to keep from running away on hills without riding the brake; and several easy-maintenance access points such as ground-level fuel, grouped grease banks, and transmission fluid that can be checked from the cab or dip stick. A new proprietary sealed touch pad was added in 2006 featuring 20 electrical functions. The pad replaces “rocker switches all over,” which “don’t last beyond 2,000 cycles and aren’t waterproof.”
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Photo: Terex
Contemporary truck designs focus on the dual qualities of productivity and power. |
The customer wants more productivity, Chesterman insists. That was a key factor in Deere’s design, factoring in durability, weight, power, life, and reliability. But another issue addressed is that because trucks are often rented, it’s important that they be user friendly because “guys are in and out of different machines all the time.”
Closing the Gap
What separates an ADT from an RDT is the job they do. Both are fairly specialized, notes Emmett, “but the gap is closing.”
Although there is increasingly more crossover in application, vast differences between the two remain. One defining difference in RDTs is the application of transmission retarders to reduce brake wear. Terex artic trucks, made in Scotland, also come with standard retarding systems. The TA25 has an exhaust brake, while the TA27 and TA30 have an engine brake. The TA35 and TA40 have dual retarding systems (engine and transmission) that can be employed simultaneously.
Because the ADT is more likely to work in more rugged conditions, Terex recently adopted a full independent front suspension on the TA30, giving it an improved ride. Hydro-pneumatic struts on all corners contribute to operator comfort. “The front suspension is similar to that on a modern high-performance automobile,” Emmett elaborates. “With coil-over damper units and half shafts, the truck rides measurably better than non-IFS trucks. The reduction of vibration in the truck may also increase the life of components on the truck.” Other features designed for operator comfort include ergonomically designed controls and instrument clusters, a 45-degree steering radius, air-ride seat, large windows, and power steering.
Productivity is one focus for Terex; power is another. “The trend,” Emmett says, “is to want higher production per man hour—or, more simply put, the ability for one operator to move more dirt in a workday.” Terex has increased payload and, in most cases, already has the highest horsepower in its class, permitting quick acceleration under load.
Other ways to improve productivity include options such as tailgates for added capacity and decreased spillage, liner packages, heated bodies, automatic lube, and ejector bodies for more efficient dumping.
Most contractors look for productivity, operator comfort, fuel economy, and reliability, Emmett reports. Other points to consider include power-to-weight ratio for increased productivity; mechanical systems with the latest technology; recommended maintenance intervals; and fuel consumption.
Fuel economy is another important aspect. Contractors want to move more material faster but without excessive fuel consumption. Terex buys its engines and transmissions: Smaller models are equipped with Cummins and ZF; larger models with Detroit Diesel and Allison. The company believes the flexibility in design allows its trucks to go faster and haul more.
Changing Gears
Perhaps no other single component influences a vehicle’s performance as much as its transmission. Transmissions ensure the efficient and effective transfer of engine horsepower to wheel horsepower for traction, pulling power, and acceleration. Over the life of the vehicle, an Allison Automatic provides improved cost-per-yard by delivering better performance and increased productivity.
Allison fully automatic heavy-duty transmissions are specifically designed for ADTs, RDTs, and other rugged, off-road applications. They offer higher horsepower and torque ratings in a compact, dependable transmission to provide larger payload capacity, better performance and increased productivity. Horsepower ratings range from 300 horsepower to 600 horsepower. Input torque ratings range from 811 foot-pounds up to 1850 foot-pounds.
Allison’s patented torque converter provides smooth shifting and the appropriate traction control for load and ground conditions without digging in or bogging down. Seamless shifting eliminates driveline component shock for smooth gear changes. Routine maintenance is made easier with easily accessible integral and spin-on oil filters, and because the automatic doesn’t have a mechanically applied clutch there’s no downtime for clutch replacement.
A Trucker’s Truck
While some manufacturers consider the articulated truck more versatile, Gauger says just the opposite: “The rigid is more versatile. The artic truck just hauls material; you need a truck to haul it to the job site.” Because the rigid truck travels the roads, weight is a major consideration. “Weight saving is more important for on-road,” Gauger affirms. “It can mean fewer trips because you can haul more.”
International’s PayStar is a heavy-duty, classically styled truck chassis with a weight rating up to 150,000 pounds. “it’s our premium model for on/off highway,” Gauger offers, “with more power than the more advanced WorkStar.”
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Photo: Volvo
The artic’s flexibility suits it to rugged, potentially muddy environments. |
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Photo: Volvo
The rigid truck’s ability to haul material on the roads adds to its versatility. |
She compares the PayStar’s 625 horsepower and 2,050 foot-pounds of torque with the WorkStar’s 475 horsepower and 1,700 foot-pounds of torque. “It’s the next generation for tractor-trailer-type operations to haul back and forth to the dump site.” She cites such advances as its multiplex electric system: one wire to a set of switches that reduces wiring in the truck and on the dash by 50%.
International’s strategy of captive engineering offers maintenance advantages, allowing the manufacturer to synchronize service intervals. That translates into fewer trips to the service bay and less downtime. It also means more integration potential for warranty issues, parts compatibility, and simplicity of maintenance.
Maintenance wasn’t the only issue taken into consideration. Operator comfort is also important. “We spent a lot of time developing ergonomics,” Gauger confirms. For one thing, all switches and controls are easier to reach and work well with gloves and big or small hands because a lot of women are in the refuse market. But the cab remains suited for large men, with enough “belly room” to accommodate the largest of them.
“There are a lot of creature comforts,” Gauger reiterates, listing woodgrain and leather seating among them. “It’s not just a plain truck. There’s considerable automotive influence in the fit and finish.” And yet, recognizing that in the construction market “they like a ‘trucker’s truck,’” she says the International still looks and feels like a truck.
Job Satisfaction
Keeping the operator comfortable and happy leads to better performance. No one knows that better than Mark McClymonds, president of the Portersville, PA–based McClymonds Supply & Transit Co., a bulk-materials hauling firm established by his father in 1983.
Feedback from his operators convinced McClymonds, a onetime owner-operator, that quality trucks like the Peterbilt 357 and 379 contributed to their job satisfaction. Because they told him the springs provide better stability, he now specifies taper-leaf front springs rated for 23,000 pounds on the 357s. He also switched to Peterbilt Air Trac rear suspensions to improve ride and reduce driver fatigue. And he’s reduced his trade-in cycle to five years, keeping drivers in newer equipment and maximizing the resale value of his trucks as well.
“The drivers are an important part of the business,” acknowledges Ray Paradis, national vocational manager for Peterbilt Motors Co. in Denton, TX. “That’s their office. Comfort equals productivity.” Focusing on interior ergonomics, Peterbilt positioned levers and controls to be reachable and is “constantly updating” its electronics, adding GPS and two-way satellite communication with the shop.
Other features include frame strength, with triple rails for rigidity and all-aluminum construction to eliminate corrosion and decrease weight. “It’s the lightest Class 8 truck,” Paradis says. Its light weight means more payload and “more payload equals money.”
Drivers aren’t the only beneficiaries; Peterbilt’s trucks were designed with the mechanic in mind. “We considered maintenance when it came to engine placement; it’s not recessed into the cab. The hood opens 90% so it’s easy to access when filling fluids. We listen to the customer and react to demands to make it easier to do the job. There have been changes, and there will be more.”
McClymonds isn’t the only contractor with happy employees. Thomas Cavanaugh Construction Ltd. in Ashton, ON, is a family-owned company involved in heavy equipment rental, road building, sewer and water main construction, commercial and residential site preparation, and land development, with 29 licensed pits and quarries producing 2 million tons of crushed aggregates annually. Their fleet includes 80 Kenworth RDTs, 150 pieces of off-road equipment, and several mobile lube trucks.
Mike Cavanagh, fleet manager, says the company likes its 30 Kenworths for the low cost of ownership, quality, and durability. His drivers like them for their operator comfort, ergonomics, ride, and because they “steer nice” and are easy to get into tight spots.
It’s not just talk. Cavanaugh’s turnover is less than 10%. Cavanaugh doesn’t want to give all the credit to the Kenworth extended day cab’s additional 6 inches of length, 5 inches of cab height, and 2 inches of belly room, but admits his drivers appreciate the legroom, 21 degrees of driver seat recline, and extra storage.
The extended day cab provides more room from the firewall to the back, adds Samantha Parlier, Kenworth vocational product manager, to promote better posture and reduce driver fatigue. Other operator-friendly features include the assisted clutch pedal that requires 50% less effort and a sloped hood for better visibility. “They can see the corners!”
Advantages extend beyond the cab. Other important factors in the T800 consist of the 22k front suspension with three-stage, tape-release springs. “When a truck is empty, it rides poorly,” Parlier explains. “This engages the springs as the truck is loaded for a better ride.” Contributing to a better ride, the rear suspension comes in a choice of air to rubber solid mounts.
The T800s haul less, Cavanaugh admits, but are “more universal,” with “faster cycle times from the quarry to the develop site.” He says this workhorse “goes pretty much anywhere, any distance,” and “does any type of work.” Parlier quotes the rigid payload at 40,000 pounds (as opposed to the articulated payload of 71,650 pounds), but says the numbers vary from truck to truck. In reality, the frame rail’s three lift axles increase payload, dependent on local laws.
“We engineer the best chassis for the application,” Parlier states, adding that Kenworth focuses on performance, durability, reliability, customer needs, service, and support. “Most of our customers keep their trucks 10 years. Companies pay for trucks to run; they need to be running.”
Cavanaugh is one of those companies keeping its trucks 10 to 15 years or longer. “We even have a 1989 T800 with more than a million miles, and it’s still productive,” he indicates. Cavanaugh says they don’t drive a lot of miles, but they drive tough miles. The T800 is specced for heavy loads and rugged duty.
It’s not an everyday truck, but the ADT is massive equipment geared for off-highway use. “Which do you need?” Parlier asks. “They’re not usually interchangeable.”