Manufacturers Fine-Tune Mid-Range Crawler Excavators

By Walt Moore, Editor | March 4, 2011
Doosan DX180LC

The mid-range of crawler-mounted hydraulic excavators has always been, so to speak, the jewel in the crown of the North American excavator market.

“Everyone likes this size tractor,” says Mark Wall, product marketing manager, excavators, for John Deere. “Many models in this size class ship well—often requiring only an over-width permit—yet they efficiently perform the functions most users need, whether digging basements, installing water and sewer lines or site development.  Seems to be the right size for many different applications.”

These machines also are a good match for residential and nonresidential construction (in better times, at least), as well as for building roads and bridges, says Doug Morris, product manager, excavators, Komatsu America. And to give evidence for the universal market appeal of this size machine, Morris notes that its use in waste-handling applications is growing significantly.

“Transfer-station and landfill operators are discovering,” says Morris, “that a properly equipped mid-range excavator can work productively in these brutal conditions with minimal downtime.”

JCB’s Ryan Connelly, heavy-line product specialist, concurs that waste-handling is a growing market, saying that in addition to added guarding and features to resist debris infiltration, waste-handling packages also might include elevated cabs and optional fronts, such as straight booms, with straight or gooseneck dippers, to allow attachment flexibility.

Despite some bright spots in the market, the general slowdown in the North American economy has caused sales of mid-range excavators to tumble in the past several years—with some estimates of that decline as high as 50 to 70 percent. Everyone’s learned, of course, not to make predictions about the “worst being behind us,” but excavator manufacturers are at least not negative about near-term market prospects.

“Last year was better than 2009,” says Komatsu’s Morris, “but still far from the levels we saw in early 2008 and especially in 2007. But there’s an increase in activity in the rental business for these machines, both for distributors and third-party rental companies, and I think this shows a growing confidence in the industry.”

Despite the depressed market for mid-range crawler excavators, manufacturers generally have kept designs fresh, yielding machines that, for the most part, are more fuel-efficient, more productive, better tailored to handle specific tasks, and potentially easier to manage than their immediate predecessors.

Tier 4-I (Interim)

Among the most significant design changes for these machines has been (or soon will be) the necessity to comply with EPA Tier 4-I/EU Stage III-B emissions standards. Machines with 175 to 750 horsepower were officially required to meet these stringent standards January 2011, and those with 75 to 175 horsepower must be compliant by January 2012. Some manufacturers will for a time use credits accrued under the EPA’s Flex Program to delay Tier 4-I/EU Stage III-B compliance, but that’s a temporary measure.

With its new three-model C-Series lineup, launched in late January, Case Construction Equipment is among the first to introduce Tier 4-I certified machines. Case uses both cooled exhaust gas recirculation (CEGR) and selective catalytic reduction (SCR) to control nitrogen-oxide emissions in its product range, but chose the former technique (along with a diesel particulate filter) for the C-Series. Deere will use a similar strategy with its new excavators, to be announced soon, and the new LBX 250 X3 likely will follow suit.

Each time a machine must comply with yet another more-stringent Tier level, users are concerned about how the latest emissions-reduction technology will affect fuel economy, and, of course, purchase prices.

“While typical CEGR systems lose fuel efficiency,” says Tim O’Brien, marketing manager at Case, “we’ve actually increased fuel efficiency in our C-Series excavators by up to 10 percent over our previous B-Series models.”

According to O’Brien, the increase in fuel efficiency results largely from design enhancements in the implement-hydraulic system, swing system and engine-idle-management system.

Although Deere’s Mark Wall wasn’t yet at liberty to detail overall enhancements in the company’s new excavator line, he did say that “in addition to making the new tractors Tier 4-I compliant and better for the environment, the company has taken the opportunity to give the customer added productivity and lower operating costs.”

Based on the history that manufacturers have for preserving fuel efficiency despite having to meet increasingly demanding emissions standards, users likely can be assured that Tier 4-I models will continue this trend.

Less certain, though, is what Tier 4-I technology might add to the purchase price of an excavator in the 40,000- to 60,000-pound weight range. Most are tight-lipped about the subject, but estimates are that sticker prices will be up 4 to 8 percent.

Tier 4-I and related improvements aside, manufacturers have in the past couple of years consistently enhanced the design of their machines. According to Komatsu’s Morris, for instance, the company’s “variable speed matching” concept is a relatively new feature that helps lower operating costs. The idea, says Morris, is to match engine speed to pump delivery, whether pump delivery is high or low.

“Conventionally, when the pumps are at high flow, the engine picks up speed,” says Morris. “When the pumps de-stroke and the swash-plate angle closes, what typically happens is that the engine speed stays high. With variable speed matching, engine speed is adjusted to match pump delivery, which results in significant fuel savings.”

Truth be told, significant fuel savings often are in the hands of the operator, because most machines provide work or power modes that allow adjusting machine performance to the task, sometimes using an “automatic” mode that makes these adjustments without operator input. Usually included is an “economy” mode that reduces engine speed and hydraulic output for light-duty applications. A Komatsu system, says Morris, actually allows the operator to choose among four settings within the economy mode to fine tune operating parameters.

In some instances, design improvements are seemingly small, but nonetheless, enhance operating efficiency.

For example, says JCB’s Connelly, if an attachment requires two auxiliary hydraulic circuits—perhaps a free-hanging grapple using an open/close circuit and a low-flow rotate circuit—by turning the low-flow circuit over to a dedicated, fixed-displacement gear pump (instead of using a flow divider), the auxiliary function is not substantially affected when another function is engaged. Also, he says, using proportional controls for two-way attachments allows more precise operation.

Chad Ellis, product and governmental sales manager, Doosan Infracore Construction Equipment America, notes another “small” change that has caught on big: “Not too many years ago, limited-tail-swing excavators were considered by some to be a passing fad. But these machines have become quite popular, and because they typically have more weight and horsepower, their digging and lifting performance rivals that of their conventionally designed counterparts.”

To Ellis’s point, these heavily counterweighted, amply powered, short-tail-swing machines (some call them “crossovers”) have the flexibility to lift and dig capably when space is not a consideration, but also to work comfortably in one lane of traffic, not two, and in congested urban areas.

Yet another significant refinement Ellis sees in hydraulic excavators of this size class is the expanded use of telematic systems, an important development, he says, because of the tremendous potential these systems have for lowering owning and operating costs, increasing machine utilization and improving the overall efficiency of fleet management. The industry still has a job to do, however, says Ellis, in educating machine owners about telematic benefits.

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