Carrying the Load

March 1, 2017

From compact wheel dumpers to heavy-duty dump trucks, grading and excavation contractors have choices to move earth in vehicles that feature more efficiencies and innovations than ever before. Bell Trucks America’s B60E is powered by the OM473 577 horsepower Mercedes engine, with a rated payload of 121,254 pounds and a load capacity of 45.8 cubic yards. It is designed with innovations that were previously commanded by rigid trucks, says Kevin O’Donnell, senior vice president of sales for Bell Trucks America.

“The B60E is well suited to hard ground applications, particularly mines and quarries with tight turns and rough roads,” he says. “In these applications, you don’t need the flotation of an ADT, so the single rear axle can take the full load and deliver the benefits of having one less axle, such as no scuffing of tires and improved maneuverability.”

The truck’s niche is where wet weather conditions can adversely affect traction, and rigid trucks would normally have to stop production when rainfalls, states O’Donnell. Among the improvements found throughout the Bell line of articulated dump trucks (ADT) is the engine, transmission, axles, dump body, and hydraulics, with all of them designed to lead to increased fuel efficiency. The engine’s increased power density means fewer liters pushing out more power.

Master everything from OSHA regulations, to high-tech safety equipment in this FREE Special Report: Construction Safety Topics That Can Save Lives. Download it now!

“Fewer liters equal less fuel burned and more savings,” he notes. “The engine burns hotter not only to regulate emissions, but also makes the engine more efficient.”

Another gear has been added to the transmission for seven speeds to provide more torque in the lower range. Combined with the Bell Transmission Software, the improved transmission allows the truck to pull away in second gear, which O’Donnell cites as another fuel saver.

Add Grading & Excavation Contractor Weekly to  your newsletter preferences and keep up with the latest articles on grading and excavation: construction equipment, insurance, materials, safety, software, and trucks and trailers.    

Also a fuel savings at high speed are the Bell wet brakes, which rotate at the same speed as the wheel and not the same as the side shaft, he adds. The dump body tip angle can be adjusted to the material type.

“The bin does not have to go up to 100% to eject the load,” says O’Donnell. “This also adds up to a fuel savings due to the high RPMs achieved during the dump cycles.”

The hydraulic system also is improved with the brake accumulator charged when going downhill or coasting, adding to the retardation power and using no fuel to run the hydraulics, he adds.

There are other improvements as well. The new E series range of Bell ADTs now includes a wider, quieter, and more spacious cabin that is fully climate-controlled, says O’Donnell.

Operator safety and comfort features include a 10-inch full-color display screen, which integrates a standard backup camera, automotive mouse interface, and sealed switch module with air suspension seat for optimal visibility. A glass door offers improved visibility of access steps and the articulation area where pedestrians are at high risk.

“For safety and ease of operation, you will not find retarder pedals or levers,” points out O’Donnell. “The retarder aggressiveness is simply set on the switchpad, or the operator can allow the truck Descent Control to do it automatically.”

Other standard safety features include Keyless Start, Bin Tip Prevention, Autopark Application, On Board Weighing, and Automatic Traction Control. Hill Assist is designed to prevent truck roll back on any slope. Doosan’s largest truck for moving material onsite is the DA40-5. It’s a 40-ton class truck, but actual capacity is 44 short tons, notes Brian Bereika, Doosan product specialist for articulated dump trucks.

Credit: Doosan
A Doosan DA40 dumps its load.

The truck is used off road in less than ideal conditions, so it is designed to be like all-terrain vehicles that will go places other types of construction equipment won’t go for various reasons, “whether it’s the softness of the ground, steepness of the grade, weather conditions or whatever that would limit the ability of other equipment to do the job,” says Bereika, adding the truck is commonly seen on large industrial, commercial, or residential sites under development.

The truck also is used for road construction. Articulated dump trucks contractors have found over the years that there are various pieces of equipment that will move dirt, whether it’s a triaxle or 10-wheeler that can come off the highway, says Bereika, adding that it can be a motor grader or a pan, or a rigid frame dump truck that requires well-maintained, smooth roads.

“But what they found over the years is regardless of the job conditions, site conditions, weather, or type of material you want to put in the body, the articulated dump truck will always do it whereas the others are limited,” he says. “Sometimes they are capable of doing it and sometimes they’re not. If you want to own just one piece of dirt-hauling equipment, the articulated truck will always do the job.”

The main challenge in the industry in recent years is keeping up with government requirements for emissions, Bereika points out. “We went from Tier 3 engines to Tier 4. Along the way, as we went from Tier 3 to Tier 4, we’ve been able to increase horsepower by about 10%. Fuel efficiency has gone up. Consumption of diesel exhaust fluid to meet emissions has gone down from interim Tier 4, to Tier 4.”

Fuel expenses are a primary concern for truck owners, Bereika points out, adding that Doosan soon plans to offer auto shutdown. “The way articulated trucks are used on a job site includes a high amount of idle time,” he says. “The wheels aren’t turning, but the engine is running. That is roughly 40% of the engine hours for articulated trucks, so auto shutdown has become important.”

With respect to transmissions, Doosan provides ZF transmissions especially for an ADT application, going from six forward gears, to eight forward gears to offer better performance on the job site. “As the site conditions change rapidly as you’re driving through them, the transmission is more efficient, and longer life is less strain on the transmission,” points out Bereika.

With increasing payload capacities, it’s more of a strain on the transmission, so they have to be larger and stronger, he says. “To help in that regard for efficiency, we’re going along with other manufacturers to automatic traction control so that if the wheels start slipping on the ground and start losing momentum, the truck will automatically engage the differential locks as necessary to maintain momentum, job performance, and efficiency,” adds Bereika.

Because the trucks are so heavy—with the largest 40-ton truck with payload of 44 short tons—”not only do we operate them on level ground, but they have to be capable of going down very steep gradient,” he says. “You’ve got as much as 160,000 pounds of gross weight going downhill at a certain speed, so you have to have good braking for safety reasons.”

Doosan offers three braking systems for its truck. The first is an engine brake that serves as the first line of braking.

“If you take your foot off of the accelerator, the first braking system that comes on is the engine brake,” says Bereika. “The second is the hydraulic retarder in the transmission, and the third line of braking is we have wet disk brakes on all six wheels.

“The idea is to being in proper gear and speed for the payload you’re carrying on a specific downhill gradient and allow the engine brake and retarder to do all of the braking without having to use the service pedal on the floor,” he adds.

Wet disk brakes run on oil and oil overheats easily, and if the operator just rides the service brakes, the system can’t hold the heat, says Bereika. “Wet disk brakes last a long time, but when you have to rebuild them if you ever do, it can be an expensive repair job. If you use the truck properly, the engine brake and hydraulic retarder will be sufficient and allow you to operate safely.”

Most manufacturers now include a gradient meter in trucks. “In the past, the operator did not know how steep the grade was either going uphill or downhill,” says Bereika. “You basically had to try it once, twice, or three times until you found out how steep the hill was, what gear you had to use, and how much braking. Now the gradient meter is on the LCD display in the cab so it will tell you how steep the grade is uphill and downhill, and you correlate that with a chart that’s on the right side window on the cab; so, if the gradient meter tells you it’s a 15% grade that you want to go down fully loaded, you look at the chart, and the chart will tell you for a 15% grade, fourth gear is the maximum gear you should use.”

It also will indicate the maximum speed for safely going down the slope and allow the engine brake and retarder to do the work and not use the service brakes, Bereika adds.

Another safety component is a front camera. “The trend a few years ago was to give the operator a rear-view camera, so when you put the shifter into reverse to start backing up, the camera would come on in the cab to show you a view directly behind the truck” says Bereika. “Now the trend is to offer a front camera and some manufacturers are offering a 360-degree view, which in the next two to four years will become mostly standard equipment.”

There is a safety system in dumping, Bereika points out. “We raise a body and start dumping the payload. That’s one of the most critical situations. The weight gets higher and higher in the air and you become less and less safe if the material is getting stuck in the body. That’s the least safe time is when you’re raising the body and dumping the load,” he says.

There is a sensor in the hydraulic system that monitors if the weight is not coming out of the body when dumping and the hoist cylinder rods are being pulled out by the load. The body will automatically start slowing down its upward movement and give the material a chance to break loose before it gets any higher, he says.

Another safety feature comes into play when the operator shuts down the engine. “If the operator forgets to set the parking brake before turning off the engine, the parking brake will automatically be set,” says Bereika.

The trucks also offer the capability to limit the top speed, which is useful in mining applications, for example, where haul road speeds must be reduced for safety reasons due to volume of traffic or site conditions. “Sometimes on a mine, they will want no equipment to travel faster than 20 miles an hour,” says Bereika. “But the truck is fully capable of going 34 miles an hour. A lot of times the operators will speed and can cause accidents or disrupt things on the haul road, so we can go into the display with a diagnostic cable and set the top speed down to wherever the site management wishes and the operator no longer can exceed that limit.”

The trucks also feature a load-weighing system. “In the past, some contractors felt if it could fit into the body, they should be able to carry it. As a result, you’d get a 40-ton truck carrying 50 tons, which can be unsafe and shorten component life. With all of that extra weight, you don’t know how heavy it is. There’s more of a chance of overturning the truck,” says Bereika.

There is now a load-weighing system that is standard equipment on Doosan trucks and becoming more common in the industry so that the operator and the site management is fully aware of how heavy the loads are and can react accordingly, Bereika says.

That may entail controlling travel speeds, limiting the load, telling the loading operator the loads are too heavy and he or she must take a bucket off to get a better idea of how much material is being moved. “It’s not only for safety reasons, but to know exactly how much material you’re moving at a certain period of time,” says Bereika.

Credit: John Deere
A John Deere 460E unloads.

Contractors who own or rent trucks are concerned about reliability, performance, and comfort, Bereika says. “They want a quiet cab, less noise coming into the cab,” he says, adding that Doosan has designed its cab for optimal sound comfort.

Doosan’s large cab offers more operator comfort, Bereika says, adding “it’s easy in, easy out, and operators like space around them in the cab. They want quiet; they want space.”

Operators also favor a quality ride, he adds. “The road can get fairly rough when you are traveling at as highest speed as possible, so they want a quality ride with a good suspension system. They’re in the trucks for a good eight to 10 hours a day, and comfort and quality of the ride is very important to them.”

Ease of operation is another desired feature. “More and more, the trucks are making the decisions automatically, so that’s a benefit for operators who don’t have that much experience,” says Bereika. “The LCD displays in the cab now offer more information, both for the operator and technical information for the mechanics who have to work on them.”

Such information includes the current status of the truck, such as what gear it is in and how much fuel is being burned. The comfort also extends to the ability to listen to music through standard Bluetooth connections.

John Deere offers five models of ADTs, including the new 260E and 310E, which is replacing the 250D and 300D. Rounding out the offerings are the 370E, the 410E, and 460E, the largest truck. John Deere has endeavored to simplify and streamline the operation of its ADTs, improving the operators’ efficiency and productivity. Deere’s ADTs include such features as a transmission retarder that maintains the speed of the truck on downhill slopes.

“It saves on service brake wear and operator fatigue as the machine maintains travel speed when the operator’s foot comes off both the accelerator and the brake,” notes Maryanne Graves, product marketing manager for John Deere.

An auto-dump feature enables the operator with a touch of a button to put the truck in neutral, engage park brake, go to high idle and dump the bed of the truck.

A traction boosting differential lock engages and disengages as necessary and also allows operators to engage on the fly, while slipping, allowing them to power through soft underfoot conditions and improve their productivity, notes Graves.

John Deere’s ADT engines all meet final Tier 4 regulations, she points out. The John Deere ADTs also feature rollover protection. Upon enabling the feature, an operator can set limits for the rear chassis level so when they are unloading or dumping the dump body of the truck, if that limit as far as the angle of the truck is exceeded, the dump body won’t raise and a message will appear on the monitor instructing the operator to reposition the truck.

“It’s protecting the operator in that environment,” says Graves. “It’s going to wait for them to get on what they specify is a safe angle to dump on and that will allow them to dump the material out of the bed of the truck and help prevent rollovers, which can be common in the ADT industry.”

Ground-level service is “very important for us to keep our operators’ feet on the ground when they’re doing their daily checks,” points out Graves. “Every morning before they start, they need to hit all of those daily maintenance items. We’re making sure they’re not climbing up on their machine to do that. It allows them to do that quickly and safely each day.”

The company’s cabs have a significantly low noise level to ensure that operators who are in them for long hours have an optimal measure of comfort, says Graves. An Adaptive Suspension Control System augments the comfort, she adds.

The John Deere ADTs also include trainer seats. “ADTs tend to be a machine where someone needs to ride along for that initial training period. The tractors have a spacious training seat next to the operator so they can do on-the-job training, allowing the operators to get up to speed more quickly,” says Graves.

A remote park brake release enables the operator to safely disengage without climbing under the machine. Auto horn alerts are integrated into the ADT and when activated, the horn automatically sounds that the truck has started, moves forward, and moves in reverse. That’s critical in such environments as quarry and mining, regulated by the Mine Safety and Health Administration, Graves points out.

The Volvo A60H articulated hauler, introduced to North America in September 2016, offers a 60-ton capacity and is a fit for contractors who typically run multiple articulated haulers on long-term earthmoving projects, notes Eric Fatyol, product manager, GPE products, Volvo Construction Equipment.

In many cases, contractors could expect reduced operating costs by replacing two smaller trucks with one A60H, Fatyol says. Shortly after introducing the A60H, Volvo announced another addition to the articulated hauler lineup—the 45-ton-capacity A45G—as well as improvements across the entire G-Series lineup, including one-ton capacity increases to the A25G, A30G, and A35G, among other updates.

The A60H and the latest generation of G-Series articulated haulers have a number of features designed to add to their efficiency. One such feature: the automatic traction control and 100% differential locks. The no-slip, no-wear differential locks work in 4 x 6 and 6 x 6 drive combinations, which employ the front two axles in full time, and the back axle kicks in as necessary, says Fatyol, adding that the design minimizes fuel consumption while ensuring off-road performance when needed.

The latest G-Series models—ranging from A25G to A45G—now feature the new Volvo Dynamic Drive and Dynamic Volvo Engine Brake (VEB) systems. Dynamic Drive is designed to provide an improved gear shifting strategy that considers the payload and the gradient of the slope. The machine will automatically detect when to choose a higher starting gear or when to shift up earlier. When conditions require, the machine will prolong the gear, ensuring maximum rim-pull. With Dynamic Drive, contractors can expect a three to 10% fuel efficiency improvement depending on the model, says Fatyol.

The A60H and G-Series lines are all outfitted with the latest Volvo Tier 4 Final engines, and the G-Series lines are all covered under Volvo’s Fuel Efficiency Guarantee. Several new safety features come standard on the updated G-Series models, as well as the A60H, such as Hill Assist and a Dump Support System. Hill Assist holds the hauler in place on steep slopes without the need to engage the parking brake. The feature automatically activates when arriving at a complete stop on a hill and is disengaged when the operator accelerates.

The Dump Support System allows the operator to see the percentage side inclination of the truck and set allowable parameters for safe dumping operation. This new feature augments the dumping process aided by Volvo’s load and dump brake technology with automatic hold and float tipping lever, designed to provide precise control for faster cycle times, says Fatyol. Other safety improvements to the G-Series and A60H include new orange accent colors for greater contrast on rails and cab entry points, as well as larger rear view mirrors for greater visibility.

The A60H also comes with a number of new serviceability improvements, including a redesigned belly plate that can be electrically lowered and raised with the same hydraulic lever that is used for the engine hood, which opens to a full 90 degrees for easy, unrestricted access. Another improvement to the A60H is the no-grease tipping cylinders, which are maintenance-free, allowing for greater uptime and productivity.

James Pierce, an operator for the Landmark Construction Company in South Carolina, notes he likes the A40s “for the amount of dirt they can haul in this soft terrain. They get down to the axles, and they’ll keep moving. We put a lot in the trucks, and they keep carrying on and getting through it. They are lighter, and they can move over this boggy material with a full load as opposed to other machines, and the gearing in them is just phenomenal the way they gear down and keep pulling.”

East Manufacturing Dump Bodies on single-unit straight trucks along with East Frame Dump Trailers are designed to specialize in on/off-highway dirt and gravel applications meeting legal highway maximum gross vehicle axle load limits.

In some municipalities’ business zone areas, this may mean the typical 80,000-pound highway limit can be increased to nearly 100,000 pounds for short-haul operations, says Charles Wells, vice president of sales and marketing. “Our East Dump Bodies and East Frame Dump Trailers are popular for in and out of quarry operation to prep plants for both concrete and asphalt,” adds Wells.

Additionally, East Dump Bodies on straight trucks are used in the final phases of road building, such as laying the base or the asphalt. They also are used in the transport of asphalt grinding material.

East Manufacturing’s dump trailer’s smooth-sided Genesis design leads to easier maintenance, more payload capacity and better load removal, says Wells. Contractors indicate it adds up to a half-mile per gallon compared to ribbed trailers. The Genesis’ aerodynamic design features two 2-inch-thick double-wall extruded aluminum panels, robotically welded vertically inside and out to protect the outer wall from dents. The dump trailer’s vertical panels are designed to be light and resist bowing better than horizontal panel systems and reduce maintenance costs because individual panels can be replaced without removing the top rail. Welding inside and out is designed to reduce corrosion.

The welded union of cross-members, floor plates and sidewalls are intended to result in trailer strength. For a significantly strong floor-to-wall attachment joint, cross-members and floor plates interlock into the bottom rub rail, forming a pocket to accept the sidewall panels.

A 3-inch spacing of interior panel ribs is designed to provide eight times more wall surface support than external posts. The outboard Genesis design provides more capacity than external post-style trailers. The integrated trailer body resists weight shifting and twisting, which may lead to tipping.

Thicker aluminum in high wear areas is an available option for the last 4 feet inside the trailer. “Ground control of gates and tarping operations are increasing for easier and safer egress and exit from trailers,” says Wells. “For years, East has provided man doors on its Dump Trailers, but in the last year, East has had several orders of side man doors being incorporated into straight trucks.”

Warren Anderson, product manager for excavators and dumpers at Wacker Neuson, points out the wheel dumpers are like “small dump trucks” used primarily in tight areas.

Wacker Neuson offers four models of wheel dumpers: 3-ton, 5-ton, 6-ton, and 9-ton, with horsepower ranging from 36 to 74. “If you’re excavating or hauling material, you would put it into the front of the dumper,” says Anderson. “You would operate facing your payload and then when you get to where you need to dump it, you do a swivel skip. The skip tips forward or you can rotate it 90 degrees either way and dump to the side while you’re operating.”

Common in Europe, wheel dumpers are beginning to penetrate niche markets in the United States and Canada in such applications as landscaping, golf courses, and cemeteries, Anderson notes. “Contractors can put turf tires or floatation tires on them so as to not disturb the finished ground, but a contractor can haul sand for the sand trap or mulch or dirt or anything needed to be hauled on a golf course,” he says. “The contractor can bring it to and from and dump without disturbing the neat and tidy fairways and other areas.”

Concrete work is another application for the wheel dumper. Wacker Neuson recently designed a concrete edition on its three-ton wheel dumper. It features a concrete chute on the front from which concrete is poured. They are often used to repair golf course cart paths and offer the benefit of not having to drive a concrete truck to the middle of a fairway and disrupt the finished grounds, Anderson points out.

Cemeteries such as the Arlington National Cemetery are another common application for the wheel dumper, given the confined spaces onsite. “Naturally, there is some excavation that goes on in cemeteries,” says Anderson. “Normally you’re in a tight space, and you don’t want to disrupt the area around where you’re operating. Arlington National Cemetery uses more than 10 Wacker Neuson wheel dumpers.”

In addition to offering the benefit of navigating confined spaces, the wheel dumpers offer four-wheel hydrostatic drive, enabling them to be aggressive on rough terrain, says Anderson.

Visibility is another benefit. “You’re actually operating with the payload in front of you and when you go to dump, you’re looking at where you’re dumping,” says Anderson. “In a standard dump truck, you normally have to back into an area which for an experienced operator isn’t that difficult. But for most people, backing a giant dump truck into an area to dump is a little bit challenging.

“You raise the bed, and you can’t really see what’s dumping. The advantage on the wheel dumper is the operator sits up a little higher and is looking over the front of the payload.”

Wacker Neuson’s 6- and 9-ton models feature a standard front view camera to help see what’s in front of the skip.

A feature Wacker Neuson is developing for the North American market is a dual view dumper. While operators are currently in a fixed seating position, in a dual view dumper, the operator can flip a lever and spin the entire seat and steering column around.

“Let’s say you’re working on a golf course, and you fill the front up and want to pull out of there and drive away. You can turn the seat around and operate it more like a standard dump truck, which will increase your visibility even more when you’re roading the unit,” says Anderson. “When you get to the point where you need to dump again, you can turn the seat back around and have the visibility back on your payload and for the dump.”

Ergonomics of the wheel dumper aligns with that of other light compact equipment, notes Anderson. “It’s got a spacious cab similar to cabs on other compact construction equipment. The control lever is much like a skid steer or wheel loader,” he says. “Travel speeds range from 13 to 17 mph, so although they’re small, you can really haul across a golf course or construction site with them.”

Because they are smaller than a standard dump truck, the wheel dumper offers more fuel efficiency, “more along the lines of a compact wheel loader versus a giant diesel, eight- to 12-cylinder-high horsepower dump truck,” says Anderson.