Grading and Excavation Contractor | Compact Excavators Take Off

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Photo: Gehl

Some recent advances include hydraulic efficiency, operator comforts, and zero tail-swing.

By Daniel C. Brown

Compact excavators have finally caught hold in the US. Through 1998, fewer than 10,000 compact excavators were sold each year in North America, according to Volvo Construction Equipment. But last year nearly 30,000 of these little diggers went to work on job sites across North America. “Their popularity has been skyrocketing,” says Dan Rafferty, Volvo’s product specialist for compact excavators.

A couple of factors explain why. One is that construction sites in cities and many suburbs are increasingly tighter, requiring equipment that can work around obstructions. So, with the advent of the zero- or reduced-tail-swing feature, compact excavators are exactly the right tool for the job. Virtually all excavator manufacturers now offer one or more small machines with a house that swings entirely within its tracks.

Second, says Rafferty, operator comfort and visibility have improved greatly on most of today’s compact excavators. “The new compacts have better seats, better ergonomics, and better visibility to the bucket,” Rafferty says. “They offer an overall better operating experience. Compact excavators used to have minimal seats, and you had to fight the machine.”

“We’re seeing a trend toward more contractor ownership, rather than rent-to-rent,” says Mark Wall, product marketing manager for excavators at John Deere Construction and Forestry Co. “Contractors are finding out they can do a lot with a compact excavator, so they’re purchasing them to have in their fleet, rather than renting them.”

Caterpillar, for example, offers its C-Series of compact excavators—three zero tail-swing models featuring dig depths ranging from 10 feet, 5 inches to nearly 13 feet. Bucket-digging forces have been increased as much as 22% when compared with previous models, and stick-digging forces rose as much as 5%.

Caterpillar’s compacts, like others, have a swinging boom that enables the operator to position the machine to work next to a wall or obstruction. The operator positions the tracks parallel to the wall and can swing the boom to work at an angle nearly parallel to the wall. Case offers a similar feature—the boom and arm swing 70 degrees to the left and 60 degrees to the right.

Efficient Hydraulics
In general, hydraulic systems on compact excavators have become more efficient, says David Wolf, brand-marketing manager for Case Construction Equipment. Today’s hydraulic systems make better use of hydraulic flow than former systems did. The result is better fuel economy, longer component life, and fewer components to wear out.

Gehl Co. markets Austrian-made compact excavators in the US. Made by Neuson Baumaschinen GmbH, these compacts have seen a major improvement in their hydraulic efficiency in recent years, says Brian Rabe, product specialist for Gehl compact excavators. “In the past 10 years, the hydraulics have come a long way in terms of the balance between precision and performance,” Rabe says.

Back in 1999, Gehl’s excavators had a two- or three-pump system, he says; not much priority was given to one pump over another. Today, the hydraulic drive motors have an automatic two-speed system that senses a load and downshifts to a lower gear in the gearbox on the hydraulic motor, says Rabe. “It downshifts to apply more power with the same hydraulic flow and pressure,” he says.

Caterpillar and others offer load-sensing hydraulics that optimize oil flow based upon demands on its compact excavators. The result is smooth, multifunctioning operation and greater fuel efficiency. And Cat’s compacts have an auto-idle system that decelerates the engine to idling speed six seconds after the operating levers return to the neutral position. When a lever is moved, the engine automatically resumes operating speed. The system reduces fuel consumption and noise.

“We’re on our third generation of compact excavators,” Wall says. “We have improved the operating efficiency and increased the digging forces of our machines. We’ve made them more productive, improved uptime, and lowered their operating costs.”

Deere offers four models of compact excavators, with digging depths ranging to more than 12 feet with an optional long arm on the largest. The smallest is the 17D, which features a 14.8-horsepower engine and a 7-foot, 9-inch dig depth with the longer arm option. All four models have zero tail-swing except the 17D, which is a reduced-tail-swing machine.

Deere’s compact excavators have begun to emulate their larger, full-size brothers, Wall says. One example is the automatic shift between lower-speed propel and higher-speed propel. Another example is the automatic idle feature, which Deere also offers on its compact units. Here’s another example: Bushings in the boom and bucket on Deere’s compacts are made of powder metal, which has oil-impregnated pores. As the grease weeps out, oil releases from the pores to lubricate the bushing.
At the boom-to-bucket joint, Deere applies a tungsten-carbide coating to reduce wear. “It helps protect that joint and gives you a longer-lasting joint,” Wall says.

If you order a cab on a John Deere, you get heating and air conditioning. “The contractors want the same comfort on a small excavator that they get on the larger models,” he says. What’s more, the boom, arm, bucket, and blade are all operated by pilot-operated hydraulic-over-hydraulic controls. Pilot controls are low-travel, low-effort for easier operation and less operator fatigue. Deere’s machines also have a cup holder and a 12-V outlet for a cell phone.

Case offers five models of compact excavators, ranging from the 15-horsepower CX17B to the 41-horsepower CX50B. All of them have zero tail-swing. And on the CX17B, you can narrow down the tracks to squeeze through a 39-inch opening. Case also offers steel and rubber tracks, pilot controls, a line of thumbs, long arms and short arms, and single-acting and double-acting hydraulics for attachments. A standard control pattern change kit allows operators to have the pattern they’re accustomed to using.

“Case puts an emphasis on serviceability,” Wolf says. A side panel folds aside to reveal hydraulic valving, the hydraulic tank, the radiator, cooling system, and major hydraulic lines. In the back, an access panel covers the engine area, with oil fill, fuel fill, engine oil filter, coolant overflow bottle, and so forth.

Operator Comfort
In recent years, most manufacturers have improved operator comfort on their compact excavators. Case’s new B Series models have a 20% larger operator’s platform than on previous models. And the design of the three-post rollover protective structure (ROPS) on the B Series makes it easy to get into and out of the excavators. Plus, the three-post ROPS design improves operator visibility over the four-post models.

On Caterpillar’s compact excavators, a suspension seat, console-mounted implement controls, and adjustable wrist supports help reduce operator fatigue. Pilot hydraulic controls need little effort. Switches incorporated into the joysticks provide easy control of boom swing and auxiliary hydraulic functions. The machine monitoring system is mounted near the operator’s line of sight to ensure that gauges and warning lights can be readily seen.

Like Case, Volvo offers a three-post ROPS. The rear left corner of the house does not have a post, a feature that improves visibility to the rear, says Rafferty. Cab heat and air options are available on Volvo compacts. And the high-backed suspension seat is super-adjustable. Not only does the seat and control console move fore and aft as a unit—the seat moves relative to the controls. “Our machine will accommodate operators of all sizes,” he says. “We don’t force operators to go on diets.”

Moreover, Volvo’s cab is isolation mounted with rubber disks to prevent noise and vibration from reaching the operator. Volvo’s compacts feature load-sensing hydraulics to provide more fluid power where it’s demanded. And the machines have a direct connection of the slew motor to the slew bearing. (Slew is house rotation.) That direct connection differs from some manufacturers’ machines, which place a reduction gear between the slew motor and slew bearing. The benefit of the direct connection, says Rafferty, is improved responsiveness to the operator’s command; there’s no delay in slewing.


	Three New Excavators

Gehl offers 12 models of compact excavators, ranging from the 18-horsepower Model 153 to the 99-horsepower 1202. On two Gehl compact excavators, the 223 and the 373, the operator can elevate one side of the house-and-boom upward 15 degrees. That means you can dig a vertical trench with the tracks resting on a 15-degree slope. “You used to have to bench the surface to make it level,” Rabe says. “With both of these machines you don’t have to bench, so you realize about a 30% to 40% time savings. You don’t have to remove material and then replace it after you’ve backfilled the trench.

“Gehl has one of the largest cabs by weight class in the industry,” Rabe says. Gehl compacts with zero tail-swing, he says, have a side-mounted engine and rear-mounted hydraulic valves and tanks. That means the cab could be larger than the competition.

In some cases, he says zero tail-swing is better for lifting and placing loads than is a conventional model. That’s because the weight is more evenly distributed from side to side on a zero-tail-swing model. “We offer pilot controls on all functions except the dozer blade on two models,” Rabe explains.


	Top 10 Features of a Compact Excavator

he following functions are pilot controlled on Gehl excavators: joysticks, the travel pedals, the auxiliary hydraulics, and the boom swing. “To my knowledge nobody else does what we are doing with pilot controls,” he asserts.

A number of other companies offer compact excavators, including Komatsu, JCB, Takeuchi, Kobelco, Vermeer, Mustang, Terex, and Hitachi.

JCB offers 10 models of compacts, ranging from the Micro model, with a 6-foot, 2-inch dig depth, to the Model 8080, with a 13-foot, 10-inch dig depth. JCB markets the following features on its Model 804 Super.

A new powerful Nachi slew motor improves slew speed and torque.
A new roof window allows excellent visibility at the increased load over height. Large, flat glass areas and a low right-hand side window increase visibility.
Repositioning of the heater and the fuel and hydraulic tanks has enabled JCB to improve visibility.
An extensive bucket selection is available, ranging from 9 inches to 4 feet in width.

The Perkins 100 series engine on resilient mountings delivers 25.7 horsepower and is easily serviced by the lightweight bonnet, says JCB. The cooling package has improved resistance to site damage and better performance, even when used in the most arduous conditions.

Mustang offers 11 models, ranging from 3,500 pounds to 25,000 pounds in operating weight. Standard auxiliary hydraulics permits the use of hydraulic hammers, earth augers, grapple buckets, and other attachments to add more value on the job site.

All Mustang models feature an advanced high-output hydraulic system that allows simultaneous multiple hydraulic functions without loss of speed or power, the company says. Mustang accomplishes that feat through the use of a double variable-displacement pump and self-balancing power regulation to provide more speed and more power. Units feature offset digging as standard on all units.
Almost every company that markets a full-size excavator also supplies a compact excavator. And as Wall says, the full-size features are making their way into the compact lines. So jump in the pickup, go to your best dealers, and check out these compacts. You’ll be glad you did.

Writer Daniel C. Brown is the owner of TechniComm, a communications business.

GEC - Buyers Guide 2009

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