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Additional Article Content

• GPS Speeds Airport Grading

Larry Roberts says he couldn’t have done a major soil stabilization and grading project at Dulles International Airport (Washington, DC) without a Global Positioning System.

“The entire job was stakeless,” says Roberts, who is manager of the soil stabilization division at Slurry Pavers Inc. in Glen Allen, VA. The Dulles project involved using Portland cement to stabilize 630,000 square yards of soil for a new runway, associated taxiways, and aprons.

Roberts ran two Wirtgen stabilizers for most of the project. The contractor would spread Portland cement at 45 pounds per square yard, then dry mix it 12-inches deep with a reclaimer. One of the stabilizers then pushed a water tank and mixed water into the soil. Compaction was the next step, followed by fine grading.

For the finish grading, the contractor used two motor graders—a Caterpillar 12H and a Volvo 720B—both equipped with Topcon Millimeter GPSs. The Millimeter GPS uses a laser to achieve grading accuracy within one quarter-inch, Roberts says.

“Everything ran off our 3D model of the site,” says Roberts. The 3D model, loaded on a flash card, is entered into the control box on the graders. “The advantage of the 3D GPS is that you get more accuracy on the grade. You save everybody money because you don’t overuse stone and concrete. Plus, you can grade much faster with a whole lot better accuracy.

Roberts says the Topcon GPS cost him $120,000 for an entire system. And it paid for itself on the Dulles Airport project alone, he says, by eliminating waste of base stone and concrete pavement.

“Plus, you’d normally need three or four people checking grades and pulling stringline, but with this GPS system you cut all those people out,” Roberts says.

The Millimeter GPS relies on a laser transmitter, set up along the grade, to shoot a vertical fan-shaped beam to the receivers on the motor graders. The laser beam essentially controls the height of the grader’s blade—to within 0.25 inch, Roberts says.

Wheeled Excavators
Wheeled excavators perform well on paved and unpaved surfaces and offer the ability to travel significant distances quickly—several miles, in rural environments. Such mobility makes the wheeled excavator a valuable and versatile tool. Plus, wheeled excavators can mount virtually all of the same attachments used on tracked excavators.

A wheeled excavator is like a utility infielder—it can dig trenches, break concrete, lift and lay pipe, clean ditches, and even trim trees.

Caterpillar says its D-Series of wheeled excavators—the M313D, M315D, M316D, M318D, and M322D—deliver increased lift capacities and faster cycle times compared with the C-Series machines they replace. And Cat says the D-Series’ fuel efficiency is 7%–8% greater than that of previous models.

Each of the new D-Series wheeled excavators has added a dedicated hydraulic pump for the excavator swing function and now features a heavy-lifting mode, boosting lift capability by 7% at the touch of a button. The new systems accelerate essentially all excavator functions and produce power that the operator can feel and put to work, says Caterpillar.

The D-Series wheeled excavators range in size from 127 net horsepower with an operating weight of about 31,000 pounds to 166 net horsepower with an operating weight of about 48,000 pounds.

At Conexpo, Volvo Construction Equipment introduced a fourth model to its C-Series wheeled excavator range—the EW210C. It’s the largest wheeled excavator produced by Volvo. The new model has a new engine and new cab as well as improved hydraulics, boom/arm, controls, and environmental impact.

The EW210C is powered by a Tier 3–compliant Volvo engine featuring the latest V-ACT (Volvo Advanced Combustion Technology) and generating 161 horsepower.

The engine produced high torque at low engine speeds, allowing fast hydraulic response and what Volvo calls “ultra-efficient” fuel consumption. The engine management’s anti-stall system balances maximum available power to hydraulic output, which prevents the engine from becoming overloaded regardless of engine speed or pump demand.

At a glance, the EW210C offers a variety of features:

• Smooth, load-sensing hydraulics—A higher-torque swing motor means faster cycle times when working on slopes or placing loads.
• An improved cab—Better controls, more space, more glass, and less noise and vibration. A larger cab offers more floor space and better visibility, not to mention class-leading climate control.
• Easier service—Ground-level access makes inspection and servicing convenient and safer.
• Maneuverability—An optional two-piece boom offers increased agility, allowing the operator to work in tight spaces or perform parallel digging.

John Deere offers two models of wheeled excavators: the 121-net-horsepower Model 180CW and the 148-net-horsepower 210CW. Deere says the 210CW has a short wheelbase that allows it to slip into close quarters easily. For up-close work, Deere recommends the two-piece boom.

The one-piece boom delivers the reach and lift capacity you need for longer-distance work.

With either model, you can shift from low to high or high to low on the go. The two-speed powershift transmission in both models ensures a smooth shift every time. All controls are easy to reach, and their arrangement makes ergonomic sense.