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Digging Darwinism
Genetic adaptations and inherent trait selection don’t happen overnight. It takes some machines longer than others to find the right blend of mechanical mutation to produce a new species of machine. While the small loader was well into its development in the 1970s, the mini excavator was just starting to make its debut into the equipment world.
The mini digger, typically characterized by its dig depth between 5 and 20 ft and tracked undercarriage, was first found in Japanese and European lands. But it wasn’t until nearly a decade later that the mini excavator migrated to U.S. markets. Since then, the market has been growing steadily. But with the drop off in residential construction, the mini excavator industry is starting to level out.
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| To get closer to objects and perform more specialized tasks, the mini excavator
evolved into short swing radius
and zero tail swing machines.
In this confi guration, the
excavator house stays within
the tracks of the undercarriage
when swinging the boom. |
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“The mini ex market is down, down, down,” says Rafferty. “Last year for June the industry did 3,000 [units]. This year, we’re down to 2,100. It’s a little bit of a shock. The mini ex market was one of the fastest growing markets and it reached its pinnacle. Now it’s dropping off. But utility work is keeping it up. That’s why we’re only down 28 percent as an industry and not 40 or even 50 percent. There’s always a need for new power lines and other utility work.”
“About 20,000 units are sold in the mini ex market,” adds Darren Wilson, MHE Industry Manager, North America — Caterpillar Inc. (NACD). “For utility markets it varies based on reporting because there’s no specific utility category. It’s lumped into residential, commercial and so on, but I’d estimate that a quarter of the mini excavators sold do some utility work.”
Electrical and plumbing are the most common utility applications. Many of these applications don’t require contractors to dig deeper than 4 to 7 ft, perfectly in range for a mini excavator. But it’s their compact size that gives them the edge over other digging machines.
To squeeze itself onto tighter jobsites, the mini excavator evolved into short swing radius and zero tail swing machines. In this configuration, the excavator cab stays within the tracks of the undercarriage when swinging the cab. That means that these machines can work right up against houses or buildings and on sidewalks and roads without the fear of the operator banging the rear of the machine into an object. For even closer-quarters snaking, retractable undercarriages are also an option on some machines — allowing the excavator to constrict the undercarriage to get through backyard fences and tight squeezes.
“Utility contractors like these machines for the relatively low ground pressure they provide, and the fact that they can trench quickly in a small space,” says Mark Wall, Product Marketing Manager, Excavators for John Deere Construction and Forestry. “In addition, tracked compact excavators with low ground pressure can be moved easily from house to house. Because of their reduced weight, they can be transported without the operator needing a commercial driver’s license, by putting it up on a trailer. So the compact machines provide great maneuverability and flexibility.”
In addition to trenching, these short, long-armed machines are often used to place small diameter pipe. There are typically two methods for pipe placement — through slings rigged to the excavator or utilizing a hydraulic thumb. If you don’t have a thumb attached to your machine, the sling method would be the most likely option.
“Most guys use a dual strap with two eyes,” explains Wilson. “They run the strap from the mini ex to under the pipe and then connect them at the eye holes of the machine. They generally try to find the center of gravity on the load before lifting. When lifting, it’s important to keep the load as close to the front blade as possible for maximum lifting capacity.
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| When placing pipe with a mini
excavator, try to fi nd the center
of gravity on the load before
lifting. When lifting, it’s important
to keep the load as close
to the front blade as possible
for maximum lifting capacity. |
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“There are two ways to move the material once it’s lifted: 1) stick and boom or 2) lifting the load and tracking the machine,” he continues. “You want the machine positioned as close to the hole as possible because when you lift the load, you’ll lose stability. So, the stick and boom movement technique is optimal to keep the machine in one place. Another thing to keep in mind is as you reach out with the load, the max. capacity decreases.”
If you do have a thumb attachment, that would be the best way to move pipe. But be careful — pipes don’t grip as well as, say, tree trunks. Too loose a grip will let the pipe slip out, where as too tight and you’ll end up with crushed pipe.
“A good way to grab the pipe is to raise the blade and trap the pipe between the blade and the ground,” recommends Edgar Chavez, Director of Marketing for New Holland and Kobelco Construction. “So when you grab it you can get a grip on it before moving it. It’s also a good idea to wrap a chain around the pipes once the thumb has grabbed it.”
In addition to a thumb attachment, a mini excavator also offers auxiliary hydraulics and quick couplers for easy attachment changing. “[Mini excavators] can switch from a bucket to a hammer to remove hidden obstacles, be fitted with a thumb to move brush and debris, use a compaction wheel to compact the trench or use the dozer blade to backfill or level off a pad,” says Dave Wolf, Marketing Manager of Excavators for Case Construction Equipment.
One of the more unique evolutionary adaptations of the mini excavator is the backfill blade on the front of the machine. In addition to adding stability when excavating, the blade makes quick work of backfilling and grading once the excavating has been done, the pipe’s been placed and it’s time to move onto a new task.
“A lot of utility contractors will use the mini ex as a dual piece of machinery, especially with the dozer float option on Cat machines. Grading applications are handled because even a moderate operator can produce an exceptional grade,” says Wilson. “The dozer float allows the dozer blade to deactivate the hydraulic circuit to allow the blade to free float with gravity. So the operator can backfill and then drive over the trench and reverse back and the blade will match the contour of the ground. When the hydraulic circuit is activated, the operator would have to manually be controlling the blade height which often leaves a washboard grade, rather than a smooth one.”
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| Some species, like the skid steer and mini excavator,
evolved on similar tragectories and inhabit the
same work space, creating a community of equipment
survival. The skid steer and mini ex tag team is
among the most popular and productive examples
of this equipment behavior on the jobsite. |
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Another popular blade option is a four-way blade that can be hydraulically controlled to angle left and right, as well as up and down. Angle the blade left or right and one pass down the spoils you can backfill a small trench.
Naturally Selecting Equipment
Stepping into the compact industry doesn’t take as much capital as the larger equipment — you can get your hands on a skid steer for between $16,000 and $40,000 and a mini excavator for between $30,000 and $60,000. Of course, the price of renting these machines is far less. But if you find yourself attached to the mini machines and are using them more than 65 percent of the time, it’s time to buy.
“At certain times, of course, contractors want to conserve their outlay of cash, so renting rather than buying is a short-term option. But the decision also depends upon the job at hand,” says Gregg Zupancic, Product Marketing Manager of Skid Steers for John Deere Construction and Forestry. “Rental contract periods provide complete flexibility for the contractor, but as you extend the rental period into months or more than a year, your economic incentive for renting instead of buying a machine diminishes. Renting also provides an inexpensive way to try out new pieces of equipment, almost as a paid test drive or demonstration. Without committing to a long-term purchase, you can get to know how a skid steer or compact excavator fits your needs.”
But evolution never stops, even in the equipment industry. Compact utility loaders (also called mini skid steers) evolved from the mighty skid steer loader and even new variations continue to crawl out of manufacturer think tanks. One of the most successful has been the compact track loader, which offers a tracked undercarriage as opposed to wheels for better floatation and less ground pressure for delicate worksites. Excavators, on the other hand, have similarly taken on wheeled undercarriages for quicker mobility around a jobsite. It’s only a matter of time and demand before a new variation of tiny machines fills a niche.
Jason Morgan is Associate Editor of Utility Contractor.
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