The key design goals for hydraulic excavator manufacturers can be summarized, without too much risk of over-simplification, as “higher” and “lower”: higher availability, fuel economy and flexibility; and lower operating and maintenance costs. The feature lists of most recent model introductions consistently reflect these objectives, with degrees of design sophistication ranging from the basic — heavier components, easier maintenance access and quieter operation, for example — to highly refined engine control and sophisticated machine-health monitoring systems.

The past several months have seen entries from Case, Hitachi, Hyundai, Kobelco and Komatsu in the light-to-medium machine categories, with operating weights spanning a range of 50,000 to almost 250,000 pounds.

• Case Construction Equipment introduced the 153,400-pound CX700, which fills a vacant weight slot between its CX460 and CX800 models. The CX700, powered by a Tier 3-certified Isuzu diesel rated at 425 net horsepower, digs to 31 feet 11 inches and reaches to 46 feet 11 inches at ground line. For improved durability, Case designed the CX700 using the frame from the heavier CX800.

  The new model provides a familiar set of features for long-time customers, according to Case, including four work modes, auto power boost and a climate-controlled, iso-mounted cab; it also includes several new items — among them, a switch that allows the operator to give priority to either the boom or swing functions. By flipping the boom priority switch, the operator channels flow and speed to the boom, which can be helpful in certain situations such as lifting materials out of a deep trench or into a high truck. The CX700 has retractable side frames and an optional counterweight removal device for easier transport.

  Case also has upgraded its CX330 model, increasing power and improving fuel economy. The engine that now powers the CX330 is fully electronic and uses a high-pressure, common-rail injection system that provides a 5% increase in horsepower and 8% to 10% better fuel economy, according to the company.

  Case notes that a number of standard features on the CX700 are upgrades for the CX330, and will be applied to larger Case excavator models moving forward. Key upgrades include improvements for ease of maintenance and serviceability. Both the CX330 and CX700 feature EMS (easy maintenance system) lubricated, impregnated bushings throughout the boom and arm for extended lube intervals of up to six months or 1,000 hours. Engine oil filters are now vertically mounted in the pumphouse access area to allow for easier servicing. An upgraded cooling system and finer fuel filtration capability are additional features on the CX330 that will be incorporated into future models and upgrades.



• The 79,600-pound SK350LC Acera Mark 8 excavator from Kobelco Construction Machinery America features a 264-horsepower turbocharged, electronic fuel-injected Hino engine that is Tier 3-certified. According to the company, it can dig down to 24 feet 10 inches and reaches to 36 feet 3 inches at ground line. A boost switch on the new excavator provides 10% more power on command for increased bucket breakout force, without time limitations. The new excavator is designed to provide excellent drawbar pull for grading and hill climbing under load.

  Major features include Kobelco's Independent Total Control System for smooth hydraulic control, and an ergonomically designed cab with a 7-position suspension seat. All major controls — including double-flow hydraulics for powering tools and attachments, mode selection switches and heavy lift and independent travel switches — are located on the operator's right side for easy access. To reduce maintenance time and boost productivity, all routine servicing and fluid checks can be performed with ground level access to filters, batteries, sight gauges and couplers.



• Hitachi's Zaxis Series excavators were introduced in 2002, followed in 2006 by six Dash-3 upgrades to the series covering the 24- to 85-metric ton range. In 2007, Hitachi unveiled two utility-class model upgrades, the ZX200LC-3 and the ZX225USLC-3. Although these units fall below the weight and capacity range typically used in quarry applications, their feature set illustrates the common design trends adopted by manufacturers throughout the larger weight classes. For example, Hitachi notes that the 47,015-pound Zaxis 200LC-3, powered by a four-cylinder Tier 3-certified Isuzu engine, is heavier, stronger, faster and quieter than its predecessor, but uses less fuel. The cab is prepped for auxiliary hydraulics. Other options include several arm and shoe sizes, super-long fronts, control pattern change valve and auxiliary hydraulic accessories. Other key features include a stronger undercarriage, X-beam, side frames, idler brackets and front attachments. The ZX200LC-3 also has higher horsepower, swing torque and drawbar pull than its predecessor. It holds 10.6 gallons more fuel and hydraulic oil, but requires a half a gallon less engine oil.

  The slightly heavier (53,440-pound) ZX225US LC-3 shares the same engine and improvements as the ZX200LC-3 but is configured differently, with a rear swing radius that is 3.5 feet shorter than the ZX200LC-3 (thus, the Ultra Short designation). Because of its truncated length, Hitachi says the ZX225US LC-3 is 6% more stable than the ZX200LC-3, but offers essentially the same cutting and dump-height capabilities.

  During mid-2006, Hitachi introduced the Zaxis 350LC-3, which replaced both the Zaxis 330LC and Zaxis 370 models. The Zaxis 350LC-3 weighs 77,269 pounds and comes standard with a 13-foot 1-inch arm, a 16,314-pound counterweight and 32-inch triple semi-grouser shoes. Other arm lengths are optional. Powering the 350LC-3 is Isuzu's new AH-6HK1YSA-01 Tier 3-certified diesel, rated at 271 net horsepower. The engine employs a common-rail, fuel-injection system and cooled exhaust gas recirculation (EGR).

  Dash-3 improvements include stronger undercarriage and strengthened upper structure for the 350LC-3. Track links are thicker and three track guards protect track links from disengagement during steering. The track chain is sealed and lubricated. The upper structure features Hitachi's D-section frame skirt for increased rigidity. At the arm-bucket joint, the arm top is hardened with tungsten-carbide thermal spraying for greater wear resistance at its contact surface with the bucket.

• Komatsu America Corp.'s new PC1250-8 backhoe and PC1250LC-8 backhoe/hydraulic shovel have an operating weight of 234,790-254,000 pounds for the backhoe model and 244,790 pounds for the shovel, respectively, with both units rated at 672 horsepower. Bucket capacities for the backhoe range from 4.4 to 8.8 cubic yards and 8.5 cubic yards for the hydraulic shovel. Units are powered by a Komatsu SAA6D170E-5 engine, featuring what Komatsu says is the first cooled exhaust gas recirculation (EGR) system with electronically controlled bypass assist-type venturi. The engine is Tier 3-certified, reducing nitrous-oxide emissions by approximately 40%, according to the manufacturer. A new hydraulically driven, variable-speed cooling fan provides quieter operation and improved fuel economy. Fan speed varies with engine coolant, hydraulic oil and ambient temperature inputs, and fan rotation is reversible to aid in radiator and hydraulic cooler cleaning.

  The PC1250-8 and PC1250LC-8 backhoes have a two-mode setting for the boom: a “smooth” mode that is useful for operations such as scraping or gathering blasted rock, and power mode when maximum digging force is required. The backhoes also feature a shockless boom control to automatically reduce the amount of vibration present when operating the boom.

  According to Komatsu, the machines are designed and built to provide long service life. Booms and arms are constructed of thick one-piece plates and large castings. The undercarriage is strengthened for added durability when working on rocky ground or blasted rock; additional guards protect the travel motors and piping from rock damage. Reliable electronic devices have passed severe testing. Metal guard rings protect all hydraulic cylinders and Deutz-type electrical connectors are sealed against dirt and moisture. Hydraulic hoses are equipped with O-ring seals instead of conventional taper seals to provide extended leak-free life.

  Both models have extensive filtration systems with standard, in-line, high-pressure filters in the outlet port of each main hydraulic pump to reduce failures caused by contamination. The excavators are equipped with Komtrax technology, which sends machine operating information to a secure Web site utilizing wireless technology.



• Like a number of other excavator builders, Hyundai unveiled new models at the vast bauma 2007 construction and mining machinery trade show held in late April in Munich, Germany. Among the new machines that Hyundai planned to exhibit is the 179,000-pound Robex R800LC-7A, which represents a major class leap from the company's former top-of-the-line, 50-mt R500LC-7A, and is aimed directly at the quarry/small-mine market sector.

  Equipped with a 4.5 cubic yard bucket capacity, the R800LC-7A is powered by a Cummins QSX 15 Tier 3-certified diesel rated at 460 horsepower. Fully integrated engine control unit (ECU) reportedly offers 10 times the storage and computing power of previous models, for more efficient and intelligent engine management. All components of the excavator's structure that are subject to high stress levels have been reinforced, and heavy-duty electronic cables, and water- and dust-resistant plug connections contribute to high reliability. To minimize maintenance costs and improve efficiency, the machine is equipped with an automatic lubrication system. All major control and maintenance points are designed for maximum accessibility, while the hydraulic-oil filter change interval is set at 1,000 operating hours.

  Hyundai says the R800LC-7A employs a new generation of its CAPO (computer aided power optimization) system, providing precise control of machine hydraulics for specific jobs. A Power Boost feature gives 10% more breakout force instantly at the push of a joystick button, while working in “hammer” mode allows the pressure to drop immediately upon sudden fragmentation of the rock, which prevents unnecessary wear and damage from dry-firing. Individual operator setting preferences can be saved and recalled from shift to shift.