Compact excavators also have experienced bracket creep; the category was once capped at machines weighing 6 tons, then went up to 8 tons, and currently includes units weighing 10 tons and lower. The range is now broad enough that some in the industry are defining subsets as micro, mini, midi, and compact with no adjective for bigger units.
Why the steady increase? It was partly customer demand, partly OEM one-upmanship, and partly because the market wanted to classify machines more accurately. A lot of 8-ton machines, for instance, really were significantly bigger than 8 tons.
Others have abandoned the weight ratings altogether and say “compact” refers to anything with a blade and a swing boom; some add rubber tracks to add a third defining characteristic. That’s the approach taken by Wacker Neuson. “We refer to our new 14-ton model as ‘compact’ because it meets these three criteria even though it’s above what has been considered the weight cut-off for compact machines,” says Marcus Auerbach, director of compact equipment with the company. Interestingly, no one includes zero or reduced tailswing in their must-have definition of a compact excavator; while these are common features on these units, they’re not universal.
To meet Tier 4 Final requirements, many models that had 35- to-40-horsepower engines now have engines of less than 25 horsepower. At the same time, hydraulic systems have become much more efficient. “We’re getting more hydraulic horsepower per unit of engine horsepower,” says Tom Connor, excavator product specialist, Bobcat. If there is a drop in engine horsepower it is minimal and in most cases newer models offer better performance than the models they replace.
Customers need to be mindful of the relationship between engine power and hydraulic power, says Mark Wall, product marketing manager, John Deere. “The important thing is to have enough engine power and torque to drive the hydraulics,” he says. “Any more than that is wasted.” Demo the machine in your application with your operators and with any attachments you plan to use.
Also check that the machine performs multiple simultaneous functions smoothly at the same time. This requires hydraulics that are not only powerful but sophisticated. Terex uses axial piston, variable displacement hydraulic pumps and motors to provide both load-sensing and load independent flow division (LUDV). “With a load-sensing system, the pump senses the operator’s commands and directs oil flow to that function without stopping the other functions,” says Gregg Warfel, compact division sales manager, Terex Construction Americas.
Arm length affects performance. A longer arm gives greater dig depth, the ability to move the spoil pile back, and the ability to pull from farther when backfilling, reducing the need to reposition the machine. But a longer arm reduces breakout force and will probably require counterweights.
Manufacturers typically list breakout and lift figures using the standard configuration for a machine and usually cite a reference bucket used in obtaining these specs. Connor says customers need to be aware of how these requirements influence specs. A machine that comes standard with a quick-attach may show lower lift capacity because of the added weight. And lift capacities will vary depending on whether a bucket was used in calculating those values. “It’s also important to remember that breakout forces are theoretical values derived from mathematics that assume 100 percent efficiency. They’re helpful for comparison but don’t reflect the absolute performance of a machine on a jobsite,” Connor says.
While compact excavators are used for digging, many are prime movers for a wide array of attachments. Thumbs and grapples are popular, as are compaction tools, augers and hammers/breakers.
If you know you’ll be using your compact excavator with attachments, make sure it’s spec’d right. “The most important aspect is to ensure you have the correct auxiliary lines,” says Jordan Dey, compact excavator specialist, JCB. “Is there a need for high or low flow? Single or bi-directional flow?”
Some attachments have multiple circuits with dissimilar flow requirements. David Steger, national sales manager for Takeuchi, says these typically fall into two categories: positioning and work. He cites shears as an example. A shear would need low flow for rotation (a positioning function) and high flow for the shearing action (a work function).
Swapping attachments and buckets is much easier with a quick-attach, but because a quick attach increases the distance from the pin to the cutting edge of the bucket it reduces breakout force. “A quick-attach makes the machine more versatile,” says Dey, “but if your machine will perform one function with one specific attachment most of the time, the standard coupler will yield a more productive cycle time.”
In theory a quick-attach allows the operator to change attachments from the comfort of the cab. In practice, says Steger, this isn’t necessarily so. “A secondary lock or the need to make hydraulic connections will still require that the operator get on the ground.”
Because there are so many tools and attachments for compact excavators, the key markets are well covered. “Rental is maybe 40 or 50 percent of the market,” says John Comrie, product manager for compact excavators, Volvo. “That’s followed by utilities, landscaping, and general contracting. Attachments for these markets are readily available, but the versatility of compact excavators and their popularity in new and niche markets have created a need for attachments that aren’t yet available.”
Comrie says many of the attachments he’s seen in these specialty applications are one-offs, made by the owners. “Oil and gas contractors are making their own pipe clamps, specialty buckets, boring tools, and winches for pulling oilfield hardware. They have tasks for which no commercially-made products exist.”
Comrie says among the more unusual things he’s seen are an attachment that lifts logs and cuts them to length and an excavator with 36-inch tracks for mosquito control work and other tasks in swamps and similar soft underfoot conditions. “That required a fabricator to split and widen the frame to accommodate the design. The stick and boom were also modified.” The result is an 8-ton excavator that exerts ground pressure of less than 2 pounds per square inch.
Among the mass-produced attachments are a variety of buckets, including some that tilt and rotate. But even with a stock bucket a compact excavator offers excellent digging performance. Compared to a backhoe, Comrie says an 8-ton compact excavator has comparable dig depth of around 14 feet, is easier to maneuver, and has 360 degrees of use. “It will simply out-dig the backhoe.” He says contractors often pair a compact excavator with a skid steer loader.
Unlike most other types of equipment, compact excavators generally don’t offer optional air-ride seats. Desmond Jarvis, product manager for smaller Komatsu excavators, says their standard seat is a mid-rise, three-way adjustable with some contouring to both the back and the seat. “On machines like wheel loaders that spend a lot of time traveling and on production machines where operators spend eight and 10 hours in the cab, air ride is an excellent choice. But neither condition applies to compact excavators and our standard seat is a great design for the type of use these machines see.”
Electronics are used to manage engines and pumps, but are not used in controls. Pilot hydraulic controls are used instead. They’re favored for their simplicity, low cost, and good feedback.
Kurt Moncini, senior product manager for excavators and crawler dozers, Komatsu, says ease of entry and exit are important comfort features since operators are in and out of the cab several times during the day. Key features are flip-up foot pedals, a tilt-up left arm rest, and a sliding door that, unlike a hinged door, opens fully even in confined spaces. “In addition the sliding door resists rattling and is less likely to be blown closed by high winds,” says Moncini.
Because “compact” now covers such a wide range of machine sizes, not all comfort features are available on all sizes of machines. Corey Rogers, marketing manager, Hyundai Construction Equipment Americas, says their smallest model, the 1.7- ton R17Z-9A, comes only with a canopy. The 2.6- ton R25Z-9AK has an optional cab, but no air conditioning option due to space constraints. Larger models come with cab and air conditioning optional or standard, depending on the size. Only the largest models, the R60CR-9A (5.9 ton) and R80CR-9/R80CR-9A (8.25 ton) have digital instrumentation, two work modes, and two travels speeds.
Whereas most areas of development in compact excavators have seen big changes, serviceability improves incrementally. “In many ways it’s the same as it’s always been,” says Paul Manger, product marketing director of construction equipment, Kubota Tractor. “Oil and grease are critical. Ensuring efficient cooling is critical. Daily checks are essential.” Manger says OEMs make sure daily check points are well-marked, easy to find and easy to access. One of the incremental improvements is the grouping of like items, such as zerk fittings.
The development of long-life coolants, synthetic lubricants, and advances in additive packages for engine oils as well as cleaner-burning engines greatly extended PM intervals in the recent past. But that extension has leveled off and isn’t likely to dramatically increase anytime soon.
Maintenance needs are easier to assess on newer machines, says Tim Boulds, construction equipment product operations manager, Kubota. “Clean fuel is critical with Tier 4 engines so it must be easy to check for the presence of water in the fuel and drain water as needed. The bowl of the fuel/water separator is clear for easy viewing and water can be drained simply by opening a valve. There’s no need to open the filter assembly.”
Since the development of features has occurred across the full range of compact excavators, the choice comes back to size. But be careful of basing the choice on size category alone, says Katie Pullen, brand marketing manager of mini excavators, Case. “Size classes are primarily an OEM language and OEM language doesn’t always translate to end users’ needs. The terms that we as manufacturers use for categorizing and reporting purposes aren’t always going to be the same terms that owners and operators are using—they are more concerned with overall performance and their total cost of ownership.”
Pullen says for customers it all comes down to profitability which at its simplest is production revenue minus cost of ownership. “The right choice is the machine that meets all your needs and provides the best overall performance, regardless of how it is categorized.”