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Machine Matters

Posted By Brooke Wisdom On January 1, 2011 @ 6:00 am In In the Magazine | No Comments

Earth Moving Matchup

Large excavators and artics create true productivity duo

By Mike Anderson

If more proof was needed that large excavators are increasingly being teamed with articulated dump trucks, just take a look the players who are in this game today.

[1]

At 47.6 metric tons, the new Link-Belt 460 X2 is sized for the loading of large articulated dump truck – an equipment team that has grown in popularity as earthmoving contractors adapt their fleets to best leverage operating efficiencies.

Of the OEMs submitting information on their 40- to 50-metric-ton excavators, all but two also either directly offer or are aligned to articulated dump trucks with payload capacities in excess of 35 metric tons. (See the articulated truck roundup on pages 28-29).

Case, Caterpillar, John Deere/Hitachi, Komatsu, Volvo and Doosan (Moxy) each offer both of these machine types and in the aforementioned sizes. On the other side of the equation, of the seven large articulated dump truck OEMs, only one, Terex, does not offer the North American market a matching-sized excavator.

As evidenced with their product offerings, OEMs are clearly buying in that earthmoving customers are preferring the team approach.

Move dirt, all of a sudden,” says Henrik Larssen, Volvo product specialist, articulated haulers. “It just kind of exploded.” For a stretch from 2005 until the recession hit, the U.S. market for articulated dump trucks actually grew by 50 percent annually, says Larssen. “Pretty much, it followed the whole boom with the construction equipment market.” As contractors added excavators and other loading pieces, he says, “they needed a machine to move the dirt away with, and they went to the truck,” as compared to motor scrapers. “The scraper is more limited is application than the truck,” says Larssen. “The truck can move anywhere. You need a flat ground and long distance to use a scraper.”

The cost per ton of earth moved is another differentiator expressed by OEM product managers surveyed.

New model

The use of the 40- to 50-metric-ton excavator in a mass earthmoving application is at the core of a new model that will launch Caterpillar’s E Series excavators, says Kent Pellegrini, worldwide product application specialist. The 349E L will replace the current 345D L and “when matched up with the Cat 740 haul truck, operators will find the 349E is much faster on the swing, improving truck turn times. Typically, truck turn times are under two minutes with a 349E, depending on material density and bucket fill factors,” says Pellegrini. “Along with cycle time improvement, we have a 2-percent reduction in fuel burn due to the electric boom regeneration valve, which is a standard option on the 349E.”

Designated the 349 by Caterpillar to reflect actual machine operating weight in metric tons, the excavator will boast a net horsepower increase from 380 to 404, and have improved cab sealing and pressurization, says Pellegrini, but will remain in the established 345D L role “as the most versatile machine we have in our large excavator lineup. We can change up the undercarriage, fronts and counterweights to meet multiple application needs.” Configuring the machine to match the job process is critical, he says. A machine mismatched to the application can cause a contractor to adjust the jobsite on the fly, “for example, by continually benching down when loading a truck, due to improper boom/stick length, counterweight, bucket size and material density. Stability issues can arise if the machine was incorrectly configured or the machine is not the correct size for the job.”

[2]

Sporting new nomenclature to reflect the machine’s operating weight in metric tons, the Tier 4 Interim emissions-ready 349E L will replace the 345D L in the Caterpillar large excavator family with more horsepower and an electric boom and stick regeneration system for higher loading productivity.

As with Caterpillar’s Tier 4 Interim emissions solution, Volvo’s excavator in this size range is available with both a fixed and variable undercarriage, says Joel Escalante, Volvo product competency manager, excavators. “Customers always will go to the extreme before they jump to a bigger sized machine. As long as they work within the lifting table limitations, they know that they are fine,” says Escalante, noting that contractors loading trucks with loose, pre-dozed material will equip a Volvo EC460C L excavator with a larger bucket, moving up to 5.25 or even 5.5 cubic yards in capacity. “An experienced operator can pull up more dirt, mainly because he will curl the bucket to a specific angle so he can take advantage of the heap when top-loading. It also depends on the consistency of the dirt. If it’s got humidity for example, your heap is going to be huge compared to a very dry material.”

Escalante recommends use of a pin-on bucket for mass earthmoving, noting a coupler can, depending on manufacturer, add about 2,000 pounds to the weight at the end of the stick. “If you use a coupler, you cannot use as big of a bucket,” he explains. Also, where possible, an excavator equipped with the shorter ME boom will further facilitate use of a larger bucket.

“When working from a bench,” says Caterpillar’s Pellegrini, “the height should be about equal to the stick length and the truck body rail should be below the boom-stick pin. This will increase the cycle time and minimize cleanup of material. Sticks that are over- or undersized will have negative effects on loading techniques and cycle times.

“Trucks should be positioned as close to the machine centerline as possible,” he adds. “For maximum production, the work zone should be limited to the width of the undercarriage for stability and cycle time.”

Know your site

In tandem with product managers trained to evaluate and offer advice on the best use of equipment for a particular site, the leading OEMs offer site simulation programs that, based on the numbers actually provided by the contractor, will determine what will provide “the most benefit for his dollar,” says Nick Tullo, Volvo product marketing specialist.

“The most important thing to remember when loading an articulated truck,” advises Terex, “is to understand the truck’s capacity and capabilities. Articulated trucks work within the laws of physics – as the load of the truck is increased, the truck’s speed will decrease proportionally. It’s a simple formula of load-over-distance-over-time. It is important for both the loader operator and the truck driver to be aware of the appropriate load for the truck, and for both to adjust their production and cycle times accordingly.”

It is a team thing after all. EW

[3]KOMATSU

PC450LC-8 (new)

• 345 net horsepower

• 45.75 metric tons operating weight

• 25’8” maximum dig depth

• 53,790 pounds bucket digging force

Rolled out over the past year, the PC450LC-8 leverages Komatsu’s “all-in” approach to machine development: all major components including the engine, pumps, valves, motors and cylinders are designed and manufactured by the company. A heavy-duty boom is standard, and large, one-piece, seamless castings are used in the boom foot, boom tip and arm tip. The hydraulic system, matched to the engine, uses in-line filters on the pump’s high-pressure side for an extra level of protection to the system, says Komatsu. The excavator, as with all new Komatsu heavy equipment, features the Komtrax satellite communication system, which provides location and service meter reports, and will send automatic alerts to e-mail accounts or phones. The PC450LC-8 is available in a variable-gauge version.

DOOSAN

[4]

DX480LC

DX420LC

• 293 net horsepower

• 40.9 metric tons operating weight

• 25’4” maximum dig depth

• 59,524 pounds bucket digging force

DX480LC

• 328 net horsepower

• 47.5 metric tons operating weight

• 25’7” maximum dig depth

• 67,900 pounds bucket digging force

Progressing from the former Solar Series, Doosan’s DX Series crawler excavators in the 40- to 50-metric-ton range have two power modes – a standard mode that uses 85 percent of engine and hydraulic power for general work, and a power mode that uses 100 percent of engine and hydraulic power for heavy work. Also, there are two working modes – a digging mode for general excavation and lifting, and a trenching mode with swing priority for trench work and canal digging. An electronic power optimizing system connects the excavator’s hydraulic system and engine controls via a data transfer link, regulating the hydraulic flow rate required at various areas of the machine. The boom shape has been optimized using finite element analysis, resulting in better load distribution throughout the structure, says Doosan.

[5]JCB

JS460

• 305 net horsepower

• 46.82 metric tons operating weight

• 25’4” maximum dig depth

• 60,630 pounds bucket digging force

The JS460 is built on a heavy-duty undercarriage designed with a single-piece, steel X-frame and greased-for-life Berco track components. A range of boom designs allows the machine to be suited to the particular application. For operator comfort and efficiency, the spacious cab is equipped with fully-adjustable seats and strategically-placed servo controls, and the Auto-Shift transmission automatically shifts to and from high, mid and low gears for precise machine movement. The Advanced Management System maximizes machine performance and minimizes fuel consumption by matching the engine to the hydraulic output. Offered as a new option on the company’s excavators, proportional auxiliary controls ensure a more precise control of various hydraulic attachments, says JCB.

[6]CASE

CX470B

• 362 net horsepower

• 47.08 metric tons operating weight

• 27’4” maximum dig depth

• 55,528 pounds bucket digging force

With its full-size CX B Series excavators including the 47-metric-ton CX470B model, Case was able to boost horsepower without increasing noise, the company says. The sound level inside the isolation-mounted cab is a low 68.5 decibels, says Case, citing reinforced tubular structures for dampening vibrations. The 362-horsepower CX470B has regenerative hydraulics on the boom and arm, “as well as the bucket curl, which speeds the time required to get a bucket of dirt,” says marketing manager Tim O’Brien. Featuring multiple work modes and auto power boost, CX B Series excavators can store up to 10 auxiliary hydraulic patterns for multiple attachment use. The placement of impregnated bushings in all working-end pin locations extends greasing intervals – to 250 hours on the bucket and 1,000 hours on the boom and arm.

[7]CATERPILLAR

345D L

• 380 net horsepower

• 45.38 metric tons operating weight

• 26’9” maximum dig depth

• 58,000 pounds bucket digging force

349E L (new)

• 404 net horsepower

• 48.5 metric tons operating weight

• 29’3” maximum dig depth

• 60,250 pounds bucket digging force

Caterpillar is launching its E Series of excavators with a newly-designated replacement for the current 345D L. The 349E L, with new nomenclature to better reflect operating weight in metric tons, will offer a net horsepower increase from 380 to 404, yet is expected to retain the fuel consumption of its lighter predecessor, says Kent Pellegrini, worldwide product application specialist. A new electric regeneration system uses the boom and stick cylinder to supply energy created by gravity. As the stick and boom are operated, oil flows from the rod end to the head end, instead of back to the tank. Maintaining the 345D L stance “as the most versatile machine Caterpillar has in the large excavator lineup,” the E Series machine will be able to be configured with different counterweights, undercarriages and fronts.

[8]LINK-BELT

460 X2 (new)

• 362 net horsepower

• 47.6 metric tons operating weight

• 27’4” maximum dig depth

• 60,700 pounds bucket digging force

As part of the Link-Belt X2 Series of excavators, LBX has introduced a beefed-up 460 X2 model that combines 47.6 metric tons of operating weight with increased hydraulic horsepower for faster cycle times in digging, lifting and swing applications, the company says. With the Isuzu engine, the use of common rail fuel injection and exhaust gas recirculation technology results in a fuel-efficient, clean-burning machine, says LBX. The cab has a reinforced tubular frame, claimed to be three times stronger and supported by improved frame mounts, providing a sturdy, protective shell for the operator. To ease maintenance, LBX designed the 460 X2 with ground-level access to remote filters. An engine “green plug” has a spring-loaded release and drain hose for an easier, more environmentally-friendly oil change.

[9]VOLVO

EC460C L

• 315 net horsepower

• 47.8 metric tons operating weight

• 25’3” maximum dig depth

• 54,900 pounds bucket digging force

Suited for quarrying, pipe laying, demolition and bulk earthmoving, the 47.8-metric-ton EC460C L excavator benefits from Volvo Advanced Combustion Technology (V-ACT) providing high torque at low rpm for efficient fuel consumption. The onboard computer balances maximum available power to hydraulic output, preventing the engine from becoming overloaded regardless of engine speed or pump demand, says Volvo, claiming the machine is “impossible to stall.” A fully electronically-controlled hydraulic pump and higher-torque swing motor provides faster cycle times and increased performance, says the company. The undercarriage has been strengthened, and the structure and boom/arm reinforced. A shorter-boom ME version is available, offering increased bucket digging and stick forces.

[10]HITACHI

Zaxis 450LC-3

• 348 net horsepower

• 48.16 metric tons operating weight

• 27’2” maximum dig depth

• 57,111 pounds bucket digging force

In the ZX450LC-3 excavator, Hitachi’s HIOS III hydraulic system “matches perfectly” to the torque curve of the 348-horsepower Isuzu engine, leveraging regenerative hydraulics for faster arm, boom and bucket actions, and more powerful digging forces, says Hitachi. The HP power mode boosts arm roll-in during deep excavation; a boom-mode switch cuts vibration and impact shock-loads due to less pulling of the body. Along with cooled exhaust gas recirculation, a common rail fuel injection system that eliminates differences in suction pressure among cylinders is credited with the engine’s reduced fuel consumption. Equipped with the CRES II cab, claimed the largest in the class, the ZX450LC-3 comes standard with the ZXLink Ultimate wireless communication system. The model is available in a Mass Excavating version.

[11]JOHN DEERE

450D LC

• 348 net horsepower

• 48.16 metric tons operating weight

• 27’2” maximum dig depth

• 57,111 pounds bucket digging force

A rigid, reinforced D-channel mainframe and three welded bulkhead plates in the boom and arm provide the 450D LC excavator with the strength and durability for bulk earthmoving jobs, says John Deere. Balanced with the 348-horsepower Isuzu engine via the Powerwise III management system, generous hydraulic flow and tight metering ensure powerful digging force, precise low-effort control and multifunction operation, says the company. The machine’s hydraulically-driven fan runs only when needed, cutting debris flowing through the coolers and fuel use. For the operator, a wide expanse of glass, narrow cab posts and numerous mirrors combine for all-around visibility. The 450D LC, as with the sister Hitachi ZX450LC-3, is available in a shorter-boom Mass Excavating version providing more stick force.


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