Compact excavators have carved out a niche for themselves. Initially used in tight urban work conditions, compact excavators have proven so effective in light trenching and digging applications they started to encroach on jobs once handled by backhoe loaders. Burgeoning attachment use, effective tag-team pairing with skid-steer loaders and cheap, easy transportation requirements have helped to further solidify compact excavators’ value.
Bobcat borrows skid-steer technology to improve compact excavator serviceability
Bobcat’s 325D and 328D models appeared in 2000 and included significant upgrades over the company’s C-Series compact excavators. Chief among these improvements, according to Tom Conner, excavator product representative, was the increased breakout forces on both models.
“Other improvements targeted machine styling and operator comfort,” he says. “We expanded the roominess of the cab and operator’s station and reworked pedal layout and control placement – all with an eye toward creating a more comfortable, productive work environment.”
Conner notes Bobcat also improved maintenance on D-Series excavators. “We wanted to improve everything from checking the engine oil to accessing the main control valve,” he says. So Bobcat mounted the main control valve on the side of the excavator, where it can be easily worked on. “A flip-forward panel allows full access,” he notes.
Bobcat engineers also borrowed some ideas from the company’s skid steer line, including the full-size, rear hinged tailgate. “You get complete access to the entire engine compartment – the same configuration.
· X-Change attachment mounting system
· Full line of attachments, compatible with both Bobcat skid steers and compact excavators
· Independent boom swing for offset digging
Cat’s optimized hydraulic system delivers both power and finesse
Cat’s 302.5 moves into 2003 with minor modifications. Most notable is the addition of a hydraulic thumb option that has proven to be popular with landscaping contractors, says Matt Newman, sales support consultant.
“Our hydraulics are designed to give outstanding lift and breakout forces to maximize productivity,” Newman says. “And we have low-effort joystick controls that require minimum wrist and arm movements to reduce fatigue.”
Newman says Cat engineers wanted to give the 302.5 as many big-machine features as possible. “The 302.5’s dozer blade has a standard float function that allows effective site leveling and more efficient cleanup, especially on finished surfaces,” he says. “You just push the joystick all the way forward to the detent position and the blade will follow the contour of the ground. In addition, our work tools are designed and matched specifically to particular units to guarantee top performance.
Further adding to the 302.5’s productivity is Cat’s optional quick coupler, which allows fast and easy attachment changes. “This coupler is compatible with our entire line of work tools,” Newman adds. “And you only have to get out of the cab once to secure a tool, allowing for quick changes without the help of another person.
· Ergonomic operator station
· Low-effort joystick controls
· Optional hydraulic thumb
Low noise signature, close-in boom design for urban applications
Daewoo’s 030 compact excavator may see major design enhancements in the 2003 model year. “It has several noise-reducing features on board,” notes Chad Ellis, service manager. “Including lots of sound absorption material, an inlet silencer, a resonant muffler and engine bottom cover.”
Ellis says the unit’s low-noise characteristics combined with its boom swing design make the 030 an ideal machine for urban construction applications. “It’s not a zero tailswing model,” he says, “but it does have a close-in boom swing design that allows it to work in extremely tight surroundings.”
The 030 comes with standard pilot-operated controls and variable displacement hydraulic pumps. “We also use a direct-coupled HST for an extremely efficient hydraulic system, so there’s no need for excessive horsepower to get work done.”
Daewoo offers two cabin choices, the standard open canopy or optional enclosed cab.
· Standard pilot-operated joystick controls
· Variable displacement hydraulic pumps
· Rear hatch offers full engine compartment access
Deere’s new 27C-ZTS compact excavator debuts this month
The 27C-ZTS, a zero-tailswing model weighing in at 2.8 metric tons appears this month. “We improved many existing systems and worked hard to enhance operator comfort,” says Ryland Eichhorst, engineering/program manager, excavators. “As a result, the 27C’s operator station has been enlarged with more room between the pilot levers, and the machine’s seat has been moved farther back to give more leg room. We also reduced the pilot lever effort forces so it is now easier to fine-control the machine in finesse operations and also is less physically demanding to run.”
Continuing with the comfort and productivity theme, Eichhorst notes Deere also opted to replaced the boom swing, auxiliary controls and dozer blade with pilot-operated hydraulic controls. “We didn’t increase flow on the machine,” Eichhorst says, “but we did increase its engine horsepower (from 22 to 32 horsepower). This engine is now better matched to the hydraulic system, and with the new pilot controls makes you more productive because machine horsepower is put to more efficient use.”
· Larger, more comfortable cab
· 500-hour oil change intervals
· Easily accessible control pattern change valve
Gehl introduces Yanmar engines into its 2.5- to 3-metric-ton excavators
Gehl’s 253 and 303 compact excavator models are only a year old. But both machines will receive some improvements this year, according to Patrick Bright, product manager. “As of September, both models will be manufactured with Yanmar instead of Kubota diesel engines,” Bright says. “This move will fully integrate Yanmar power throughout Gehl’s compact excavator line.”
Bright says Gehl designers have also modified the sliding rear counterweights on both machines. “The most noticeable improvement will be easier movement of these weights and greater access provided for service and maintenance work,” he says. “On the left side of the machine, the weight slides back for access to the hydraulic pump. On the right side, access is to the radiator, oil cooler and battery box.”
Bright says both models feature an adjustable valve for the auxiliary hydraulic circuit. “This allows you to easily match the machine’s hydraulic flow for special attachment requirements,” he says. “And it saves time in that you do not have to install a flow divider. All auxiliary circuit lines are attached to the arm and are equipped with quick connectors as standard equipment.”
· Standard ISO/SAE control pattern change-over valve
· Pilot-operated hydraulic controls
· Angled track frame with upper roller
Big-machine boom design adds durability
Hitachi’s EX27U is a zero-tailswing compact excavator featuring standard boom swing for close-in work. A standard 12-inch rubber track provides a solid footing while minimizing damage to the site. A steel track is available as an option, providing additional maneuverability and traction in harsher ground conditions.
Hitachi designed the EX27U with low-effort pilot controls designed to help rookie operators get up to speed quickly. The excavator’s open-center, variable-displacement pump hydraulic system provides smooth, combined-function performance digging applications. A fully plumbed, auxiliary hydraulics package is standard.
To help reduce shocks transmitted to the operator’s station, Hitachi designed the EX27U’s boom and arm cylinders with cushioned stroke ends. The boom and stick design is identical to those on large Hitachi excavators. An anti-drift valve reduces unwanted front attachment movement, while the bucket cylinder hose is housed inside the arm for protection from impact damage.
· Isuzu 3LD1 diesel engine
· Rugged hydraulic piping and connectors
· Standard lubrication-free dozer blade
IHI premiers N class conventional style compact excavators this month
IHI continues to offer both zero tailswing (Model 30NX) and conventional compact excavators, including the new 28N model. “The 28N is our conventional model, replacing the J Series,” notes Kendall Aldridge, national sales manager. “We’re retaining conventional machines because they’re still the best type of compact excavator for contractors who are not working in urban surroundings. They’re also less expensive than zero-tailswing units and they generally have higher lifting capacities.”
Aldridge says N Series enhancements focused on the machine’s hydraulic system. “The 28N uses newer piston pump technology in a two-piston, two-gear format,” he says, giving the 28N more hydraulic flow, higher operating pressure and more auxiliary flow than its J Series predecessor. “In addition, travel speed and boom swing speeds are faster,” he says. “And all this is accomplished using less engine horsepower than the 28J did because the piston pumps are more efficient at transferring power from the engine through the hydraulic circuits.”
Other new N Series upgrades include standard suspension seats with integrated armrests and a new short-pitch control system.
· Standard auxiliary piping to the end of the stick
· Short-pitch joystick control
· 30 percent larger engine access hatch (30NX)
JCB’s new zero-tailswing models will complement conventional compact line
The 8027Z zero-tailswing compact excavator joins JCB’s 2.5- to 3-metric-ton excavator lineup this year. The new machine joins the 803 model, a conventional-tail machine.
“Zero-tailswing machines are easier for inexperienced operators to use with less risk of machine or jobsite damage, and they allow experienced operators to work extremely close to obstacles and in tight quarters,” observes George Chaney, product manager.
But there are some compromises with zero-tailswing models, most notably a reduction in lift capacity caused by the reduced counterweight area on the machine. So JCB will continue to keep conventionally configured machines in its lineup.
The company’s new zero-tailswing models will be powered by Perkins diesel engines, marketed and branded as JCB units. “That gives all of our compact machines a tough, reliable engine,” Chaney says. “Another advantage is that these engines are well-matched with our JCB hydraulics system.”
“Our hydraulic systems give you the ability to manipulate the boom, dipper stick and bucket at the same time, with a smooth feel throughout the cycle” Chaney says.
· Choice of zero-tailswing or conventional-tail models
· Rubber or steel track options
· 103-horsepower JCB four-stroke diesel engine
Third-button boom swing control helps ease restricted digging demands
Kobelco’s 25SR-2 is one of the company’s five zero-tailswing compact excavator models. It features standard single and bi-directional auxiliary valves and piping, allowing the use of hammers, augers and other attachments. A center-swing function lets operators dig around obstacles and up against walls. An exclusive third button on the left-hand joystick controls the boom center swing, and a foot pedal controls the auxiliary hydraulic port.
The 25SR-2’s hydraulic system allows you to perform multiple stick and boom movements without compromising one at the expense of another.
· Yanmar diesel engine
· Joystick-mounted third button boom swing control
· Optional steel tracks
Komatsu debuts zero-tailswing design
Komatsu offers two compact excavators in the 2.5- to 3-metric-ton class. Its PC27R-8E is a conventional style machine, while the new PC27MRx, released in August, features a zero-tailswing design. According to product manager Kenny Sato, the PC27MRx excavator has a tail protrusion of just 3 inches. “We have realized stability comparable to a conventional machine on this model by installing a standard X-weight,” Sato says. “This gives our zero-tailswing model performance almost identical to that of the PC27R-8E.”
The machine comes with a standard suspension seat and ergonomically placed pilot-operated joystick controls. A control pattern change valve is standard.
A new track system on the PC27MRx is a hybrid steel-rubber design. “It combines the best features of both rubber and steel tracks and eliminates each type’s negative traits,” Sato says. “This track is more cost-effective to run and requires less maintenance. You have to replace only damaged or worn out track shoes as needed, and not the entire track as with rubber shoes. And the shoe replacement procedure is a quick and simple job.”
Kubota optimizes compact design and weight for a more natural joystick feel
According to Keith Rohrbacker, product manager, Kubota’s 2-year-old KX61-2S model will eventually receive Dash 3 Super Series enhancements, but not in the coming year.
“We don’t use other manufacturer’s engines or components when we build our machines,” Rohrbacker notes. “This gives us a unitized machine design because all the systems are designed to work together from the start.”
Rohrbacker says Kubota also strives to equip its compact excavators with hydraulic systems capable of delivering speed, power and smoothness all at the same time. “One way we do this is by evenly distributing weight on the machine,” he says. “That allows us to boost hydraulic speed without having the machine bouncing around as a result. We also pay close attention to the unit’s center of gravity and how high up it is. The lower we can get it, the better.”
The end result of all this weight and height configuring, Rohrbacker says, is a more natural feel when working. “And,” he says, “because we can match our specs specifically to our Kubota diesel engine, we can optimize power and hydraulic settings for maximum performance while delivering outstanding fuel economy.”
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· Low-noise ergonomic cab
· Shielded hydraulic hoses
· Easy-to-replace boom and blade cylinder hoses
Trimmed-down ME 25 places emphasis on vital excavator systems and components
Mini-Ex’s ME 25 compact excavator has been available in North America since 1996. “We’ve designed this machine as close as possible to a fully hydraulic driven machine,” Harry Lao, president, says. “Our research told us that a lot of the problems that plague compact machines today are electronic in nature. Many of these systems simply aren’t crucial for running these smaller machines. And we discovered that most operators don’t need or use electronic input when they’re working on compact equipment.”
So, Lao says, Mini-Ex engineers removed most superfluous electronic systems from the ME 25 and its stable mates. “We feel that doing so increases the ME 25’s in-field reliability because every system on the machine is absolutely crucial and designed to last the life of the machine with fewer repairs.”
The ME features an ergonomic cab with fully opening windows, tilt-up operator platform for easy component access and variable displacement piston pumps for good hydraulic response and the ability to use a full range of attachments.
· Two-speed travel
· Isuzu 24-horsepower diesel engine
· Variable displacement piston pumps
Optimized air intake system for more effective engine and hydraulic system cooling
Mustang’s ME2503 compact excavator appeared last fall, replacing the company’s 2702 model. The machine took on a more modern look, with a more rounded, European-style cab. “It looks a bit like a small helicopter in some ways,” says Mark Hennessey, product manager. “But the rounded cab is also practical, providing great visibility.”
Noting the push toward more creature comforts, Hennessey says Mustang redesigned the entire cab interior on the Model ME2503. “We’ve added standard high-back, suspension seats in both the enclosed cab and canopy models,” he says. “And we worked to get the controls even more ergonomically correct. The forearm rests are now about 8 inches wide – much more comfortable than resting your arm on a narrow ledge. And they move with the seat.
“We also worked with the joystick actions to ensure more natural movement on your part when running the machine and to make the control movements easier. Then we added all-internal ducting for better heat circulation throughout the cab.”
The new design allowed Mustang to revamp the excavator’s cooling system. “Hydraulic oil becomes much less efficient as it heats up,” Hennessey observes. “And high machine temperatures are a major source of maintenance problems.”
To combat these high temperatures, Hennessey says Mustang engineers designed the ME2503’s air intake system so that clean, cool air is pulled into the machine and through a sealed interior. “Air enters the machine and moves across the hydraulic control valves, radiator and engine before exiting out the bottom of the engine compartment,” he says. “We’re able to effectively cool three major machine systems efficiently, giving you longer service life, less maintenance and better day-to-day dependability.”
· Cab-mounted releases for engine and hydraulic valve access hatches
· Rubber isolation-mounted hydraulic lines
· Centralized lube system with color-coded, remote-mounted zerts
New Holland offset boom allows close-quarter excavation
New Holland’s EC25 was one of the first compact excavators in North America to feature innovations like a control pattern change valve and full auxiliary hydraulics system, according to Paul Manger, product manager. “Not only did we provide the EC25 with a full hydraulic package,” he says, “We also plumbed the machine all the way out and added a standard quick coupler to make sure it was capable of meeting all jobsite requirements.”
Manger says servicing the EC25 has also been made easier. “The engine hood opens wide and is supported by gas-charged struts,” he says. “A removable floor plate provides full access to all hydraulic components.”
Beyond the 360-degree rotating turntable, Manger notes New Holland also equipped the EC25 with a boom that pivots 60 degrees right or left. “This is a great feature for tight jobsites like digging near foundations,” he says. “The pivoting boom allows you to work closer to obstacles with less risk of damaging the structure or the machine.”
· Mitsubishi diesel engine
· 60-degree boom pivot, left or right
· ISO/SAE control pattern change valve
Takeuchi axial piston pumps deliver moredigging force using less horsepower
Takeuchi’s TB125 combines a tough, proven design with smooth hydraulic power for a wide array of applications, according to Dan Rafferty, product manager. “We use variable displacement piston pumps instead of gear-driven systems,” Rafferty says. “We find that gear pumps tend to be more jerky and use a lot more horsepower than axial pumps.”
Rafferty notes axial pumps use allowed Takeuchi to match the system with the TB125’s 22-horsepower Yanmar diesel engine. “Sometimes we hear concerns that we’ve only got 22 horsepower,” he says. “But when you look at the specs, you’ll see the TB125’s bucket digging forces are almost 6,500 pounds. Meanwhile, some of these higher-powered machines are only generating 4,500 pounds of bucket forces. That’s because the variable displacement hydraulic pumps harness that horsepower more effectively, letting you work better while using less fuel.”
Rafferty says the TB125’s hydraulic system is also attachment-ready. “It’s plumbed down to the end of the dipper stick and ready to go,” he says.
· Full size, ergonomic operator’s station
· 28-horsepower Yanmar engine
· Variable displacement iston pumps
Hydrostatic drive and three-function hydraulic system combine to enhance productivity
Terex’s line of compact excavators, acquired last year from German manufacturer Schaeff, consists of four models, including the HR14. “The thing that impresses me the most about these excavators is their fit and finish,” notes John Poag, product manager. “They are precisely engineered and constructed, and that leads to durability and dependability.”
The HR14 is equipped with two-stage hydrostatic travel drive. A tandem-controlled, dual-piston, variable-displacement pump handles all work movements and travel drive requirements. “Our configuration is one gear pump for controlling slewing functions and the dozer blade,” Poag notes. “A separate gear pump controls the machine’s pilot pressure. This arrangement allows for three simultaneous hydraulic movements without any degradation in performance.” And, Poag notes, the HR14’s hydraulic system features a standard oil return valve to send oil directly back to the hydraulic tank when operating attachments. “This means that hydraulic oil is filtered after entering the tank, ensuring a cleaner hydraulic system and extending machine life,” he says.
The HR14 is available with a standard canopy or optional cab. “The cab has two full-size doors for easy entry and exit,” Poag says. “Both the cab and the canopy versions are laid out to ensure a large operator doesn’t feel cramped.”
A 28-horsepower Mitsubishi four-cylinder diesel powers the Terex HR14. “It’s a four-stroke engine with a very low noise signature,” Poag says. “So it’s powerful enough to excel in all compact applications, but still get good fuel economy.”
· Hydrostatic drivetrain
· Full-size operator’s station with ergonomic controls
· Two dozer blade options, standard and extra-long
Specialized hydraulic porting delivers faster cycle times and high breakout forces
The Thomas T-25S compact excavator features a long dipper arm to deliver more than 9 1/2 feet of digging depth, which is more than a foot deeper than most excavators in this class, according to Peter Mabee, marketing manager. “And we did this without sacrificing breakout force,” Mabee notes. The T-25S features a 25-horsepower Isuzu diesel engine and 5,545 pounds of breakout force.
“We also equipped this excavator with a standard regenerative hydraulic circuit on the dipper arm,” Mabee says. “Return oil from the rod end of the arm cylinder is ported through a check valve system back to the base of the cylinder. This gives you increased oil flow to the cylinder, which increases arm speed, reducing cycle times and improving productivity.”
Mabee says the T-25S has a standard high-volume hydraulic reservoir and high capacity oil cooler to ensure cool running even during the hottest summer months. “We also use a special return valve to send hydraulic oil back to the tank when running attachments on the machine,” he says. “This helps keep the hydraulic oil cooler and the excavator productive all day long.”
· Control pattern changer valve (Standard)
· Offset boom (80 degrees left, 50 degrees right)
· Piston pump drive system
Load-sensing hydraulics ensure smooth, consistent control and performance
Volvo’s EC25 and EC30 have been upgraded with the addition of a load-sensing hydraulic system. “Volvo has had this feature on its EC35 compact excavators for several years,” explains Bertrand Pollono, product and marketing specialist, compact equipment. “The primary benefit for operators is that load-sensing hydraulics allow you to run several machine functions at the same time, without compromising performance. It makes grade work much easier and gives a smoother feel in trenching operations.”
Volvo incorporated standard slide-out counterweights on both sides of the machine. “These high, wrap-around weights contribute to machine balance and help protect the body from impact damage,” Pollono says. “And when they are in the open position, technicians can easily service the engine, hydraulic pumps and battery.”
Another exclusive Volvo feature is the bottom-mounted boom hoses. “Many machines have hydraulic hoses run through the boom’s pivot points,” he says. “This practice increases wear and tear on the hoses and makes it more difficult to replace them when they fail. But Volvo routes its boom hoses at the top of the pivot point. This not only reduces wear and tear, but reduces hose replacement time to only five minutes if necessary.”
· Big-machine-style, X-shaped undercarriage
· Mitsubishi diesel engine with automatic shutoff
· Slide-out counterweights for easy service access
Zero-tailswing excavator features expanded track gauge for added stability
Yanmar claims to be the inventor of the zero-tailswing concept for compact excavators. Its Vio27-2 can turn within its own track radius, and the company says the machine’s stability and work performance equal that of a conventional- style unit. This enhanced stability is provided by the company’s patented Vio Crawler Technology by Advanced Stability system, which provides the Vio27-2 with an expanded track gauge for more stability without increasing undercarriage width. This system also uses a short-pitch rubber crawler to reduce impact shocks to the operator.
Despite the unit’s small size, the operator’s area has been enlarged on the Vio Series, offering more operator room than found in conventional compact excavators.
· Tailor-made hydraulic
· Protected, integrated boom light
· Low emission Yanmar diesel engine