E XCAVAT O R S By Curt Bennink
Explore HIGH- AND LONG- R Excavator Options
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Understand the benefits and trade-offs associated with long arm and boom configurations.
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ost excavator manufacturers offer a choice of boom and arm configurations to tailor excavators for specific applications. Most often these include a short, standard and long arm. Each of these has its respective benefits and drawbacks. Consider the shorter or mass excavation arms. “That shorter boom and arm allows additional lift capacity because you are working closer to the machine and allowing quicker loading of the truck,” says Aaron Kleingartner, marketing manager, Doosan Infracore North America, LLC. The longer arm is for contractors who need a little extra reach vs. the standard arm for dig depth or truck loading. In addition to standard configurations, many manufacturers offer dedicated super long-reach packages that can reach 60-plus ft. and dedicated high-reach excavators that can extend up to 160 ft. Super long-reach excavators are intended to reach horizontally while high-reach excavators extend vertically.
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Volvo’s dedicated high-reach machines are based on existing models with some added features to make them suitable for highreach demolition, including heavier and wider undercarriages and factory-fitted guarding.
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Whenever you put longer booms or arms on a machine, there are trade-offs to consider. “The biggest is machine balance,” says Kleingartner. The center of gravity is moved further from the center of the machine. “By physics, that means you have a lower lift capacity the further that you go out from the machine.” The same principal applies to attachments. “The longer the front, typically the smaller the attachment allowed,” says Andrew Earing, product manager, Komatsu. “Over the side stability becomes a trade-off that customers have to analyze and understand. Then there is the overall weight as it pertains to the transportability.” When it comes to the carrier, a long boom and arm doesn’t necessarily translate to greater forces on the machine itself. Despite the extended reach, longreach and high-reach booms and arms typically exert similar forces on the excavator body as standard booms and arms. “As you extend reach, your bucket sizes go down,” says Kurt Moncini, senior product manager, Komatsu. “You are trading reach for capacity. The actual load on the machine stays about the same.”
REACH FOR THE SKY The high-reach excavator allows precise, “surgical” demolition of tall structures. On some of the newer high-reach excavators,
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9/4/19 10:27 AM