Mining requires massive machines, capable of continuous operation in tough conditions. The newest loader and dozer models offer performance levels designed to meet the challenge.

By Russell A. Carter, Managing Editor

The capabilities of bulldozers and wheel loaders are, literally, yards apart. With one designed to push and the other designed to lift, they appear to have little in common. In the mining sector, however, these two types of machines are linked by some mutual characteristics: they both fall into the category of support equipment, lending their specialized design strengths to the goal of making life easier for primary production machines such as shovels and trucks; and in mining applications, they rely mostly on power and mass to move large volumes of material, thus posing a challenge to OEMs facing customer expectations for improved economy of operation in each new model. In the simplest terms, you can’t move a lot of dirt without a lot of machine.

Despite the constraints posed by the need for machine mass to move mountains, dozer and loader suppliers continue to find ways to improve fuel economy, reliability, operational flexibility and driver ergonomics. Not only do equipment designs continue to evolve, but the sector itself has seen notable changes in brand ownership as well as the entry of new players in the global market. At the top end of the loader-capacity spectrum, for example, LeTourneau Technologies, builder of the largest production wheel loader in the world—the 587,800-lb (266 622-kg), 2,300-hp (1715-kW) L2350 ‘Gen 2’—was acquired by Joy Global in 2011. And more recently LiuGong, a large Chinese construction equipment supplier, acquired a well-known Europe-based dozer manufacturer, seeking increased exposure in a wider market landscape.

The new-product stage has been quiet in recent months, as manufacturers hold back on potential rollouts until later this year when MINExpo 2012, the world’s largest all-mining equipment exposition, draws near. However, mining-class units introduced over the past year or so are, in some cases, making their opening appearance in various market regions. Komatsu, for example, recently shipped the first unit of its updated WA1200-6 wheel loader to go to a North American mining operation. According to Des Jarvis, product marketing manager for Komatsu’s mining-class loaders, this machine will be delivered to a Canadian customer. The -6’s are built at Komatsu’s Ibaraki plant in Japan, which opened in 2007 and is dedicated to production of large wheeled equipment, mostly for export.

The WA1200-6, Komatsu’s largest loader, was announced in September 2010 and officially entered the market in early 2011. The new version included improvements such as 26.2-yd3 standard bucket capacity; a new, EPA Tier 2 emissions-compliant diesel, better integration of engine and transmission for performance and economy; higher reliability of major components; and enhanced operator environment and serviceability. Other notable features included a switch to variable displacement steering pumps for more efficient power management, and the standard equipment list was expanded to include a payload meter with register and tracking functions.

Service weight for the WA1200-6, at 216,000 kg (476,000 lb) is about 5% more than its predecessor, the WA1200-3. A new boom design provides increased dump clearance, and although its rated breakout force rating is the same as the -3, Komatsu claims the -6 is considerably more stable, with static tipping load rating increasing by several thousand kilograms. The WA1200-6 also offers significantly higher air cleaner capacity, along with ground-level service points. Komatsu’s wireless VHMS (Vehicle Health Monitoring System) has been renamed Komtrax Plus throughout the product line and is included on the -6, accompanied by a new, more intuitive operator display inside the cab.

The loader is powered by a Komatsu SSDA16B160E-2 diesel, a product of the Komatsu/Cummins Industrial Power Alliance engine joint venture. It is equivalent to the Cummins QSK60 Tier 2 diesel used in other mobile equipment applications.

The most recent dozer model from Komatsu is the D375A-6, introduced in 2010 with new technology that enables higher productivity—in the case of the -6 version, an estimated 8% more than its predecessor.

The D375A-6’s lockup torque converter feature provides a direct-drive connection between the engine and transmission for more efficient use of engine power, particularly on long passes. For utility dozing in which maximum power isn’t necessary, an economy work-mode setting reduces engine output to save on fuel consumption. For general dozing, the operator can use the transmission’s automatic gearshift mode which downshifts on its own when a load is applied and upshifts to a preset when the load is removed. When ripping, the operator can select manual shifting, which again downshifts automatically when load is applied but does not upshift when the load lightens.

The dozer senses when the track shoes start to slip under heavy load while ripping, and adjusts engine output accordingly to avoid the damaging effects of slippage, which can accelerate undercarriage wear. This feature also eliminates the need for the operator to constantly work the deceleration pedal during ripping and consequently reduces operator fatigue during extensive ripping operations.

Drive-train parts are strengthened to handle the increased horsepower on the -6, and primary power train components are sealed in a modular configuration that allows them to be removed and replaced without oil spillage. The undercarriage employs the improved eight-roller, “K-Bogie” design used on the larger D475 series, which increases the length of track on the ground and also provides an extended range of track-roller vertical travel.

The -6’s blade profile was modified to more closely resemble that used on the D475 series, and the blade shoulder angle raised to reduce spillage over the blade corners. Cross joints used at the connection point of the lift cylinder and blade improve machine reliability and speed field assembly of the equipment. The -6’s hydraulic system has the higher efficiency, more reliable piston-type pumps used on the D475 series rather than gear pumps.

Other improvements on the -6 range from latching, dual insulated gull-wing engine side covers for better maintenance access, to an LCD color monitor in the pressurized, hexagonal-shaped cab. Mining-specific features include items ranging from standard work lights at the front, back and engine bay of the machine, to an uninterruptible power source in the cab that allows radio communication at all times. Manual engine shutdown switches are located in the cab and at the rear of the machine, and a battery/starter isolator box on the side of the dozer also includes a jump-start connection.

The -6’s built-in versatility allows it to handle a wide variety of dozing tasks ranging from trap loading to a shovel, dragline and dump assistance, stripping and roadbuilding to stockpile maintenance, and Jackie D. Haney, product marketing manager for mining-class dozers, confirms the -6 has found broad popularity in stockpile applications, as well as appreciation from operators who find the new machine easier to run and more comfortable than its predecessor.

The D475A is the next model of Komatsu’s mining-class dozers scheduled for an upgrade, according to Haney.

Cat’s Loaders and Dozers Updated
Caterpillar has carried out a series of updates to its loader and dozer lines, starting in May 2010 with an Extended High Lift Option (EHL) for its model 994 loader. The EHL linkage provides 42 in. (1,075 mm) more dump clearance than the High Lift linkage option, and includes new lift arms, lift and tilt cylinders, tilt links and counterweight material. The additional lift height allows the operator to back away from a truck without racking back the bucket, providing the potential for faster cycle times. The additional lift also enables the operator to dump the last pass without pushing material. The latest version in the 994 series is the 430,858-lb (195 434-kg) 994H, which when equipped with EHL linkage is rated at 35 tons (32 metric tons) payload.

Cat followed up later in 2010 with a High Lift option for its 992K loader, adding 24 in. (610 mm) of dump clearance over the standard configuration. Equipped with a 14-yd3 (10.7-m3) bucket, a High-Lift 992K offers dump clearance of 17 ft 2 in. (5,232 mm). The High Lift option reduces payload to 21.4 tons (19.1 mt) from the standard unit’s 24-ton rating but enables the 992K to efficiently load 100- and 150-ton-capacity trucks—possibly eliminating the need to move to a larger loader, which in the Cat product line would be the 993K with a payload rating of 27.5 tons (24.9 mt) for the High Lift version and 30 tons (27.2 mt) in the standard configuration.

Cat’s newest large loader, the 980K, was unveiled in March 2011 and, as the smallest of its mining-class wheel loaders with bucket capacities ranging from 5.25–16 yd3 (4–12 m3), is not typically found in high-production hardrock operations. However, it does offer a wide range of performance, ergonomic and application-flexibility features that make it well-suited for aggregate or small-mine duty and various utility-loading tasks. Notable improvements featured by the K version over its H-series predecessor include a new cab, load-sensing hydraulics, a 25% increase in lift force and a 16% increase in tilt force, along with new electro-hydraulic steering with either joystick or steering wheel control, plus Performance Series Buckets and an optional lock-up torque converter.

In mid-2011, Cat introduced upgraded versions of its popular D11 bulldozer models. The new D11T and D11T CD offer design refinements that include Enhanced Auto Shift, Dynamic Inclination Monitor, automatic climate control and available automated ripper control. The D11T and D11T CD’s 850-net-hp (634-kW) C32 engine, according to Cat, allows the machines to work fuel-efficiently anywhere in the world, with blades ranging in capacity up to 57 yd3 (43.6 m3) and operating weights up to 248,456 lb (112 698 kg). The engine is configured to meet U.S. EPA Tier 4 Final emissions standards for those geographical areas requiring stringent emissions control; for less-regulated areas, it will be configured to meet U.S. EPA Tier 2 equivalent emissions standards.

The T-Series D11s feature a new cooling package that uses a two-part radiator with aluminum bar-plate cores which contribute to durability, efficient heat transfer and corrosion resistance. The new oil-to-air hydraulic-oil cooler uses similar construction, and a hydraulic variable-demand fan uses less power, reduces fuel consumption and decreases noise.

New for the D11T and D11T CD is the Enhanced Auto Shift (EAS) system, designed to conserve fuel by automatically selecting the optimal reverse gear and engine speed, based on load and desired ground speed. When EAS is not activated, an Auto Downshift feature automatically changes gears to most efficiently handle loads. Inside the cab, a Dynamic Inclination Monitor provides a readout of tractor pitch angle and side-to-side slope angle, and Automated Blade Assist Control uses preset blade-pitch positions to simplify positioning. An optional Autocarry system automatically controls the blade during the carry segment. A new operator-presence system locks out the power train and hydraulic system to avoid unintentional machine movement when the operator is entering or leaving the cab, which can be done via an optional hydraulically actuated access ladder.

The D11T and D11T CD feature an “OK-to-Start” system that electronically checks critical fluid levels. Routine maintenance is facilitated by easily accessible filters, an optional automatic lubrication system, high-speed oil change for engine and power train systems, and ecology drains for capturing fluids for proper disposal or recycling. A fast-fill fueling system incorporates a positive shutoff to prevent spills.

Another dozer upgrade—the D9T—was announced in November 2011. The 110,000-lb (49 900-kg) operating-weight D9T is powered by a C18 diesel rated at 410 net hp (306 kW). For improved comfort and efficiency, a low-effort electronic control handle gives the operator single-hand control of all dozer functions. For added safety, a Dynamic Inclination Monitor provides readouts of the tractor's pitch angle and side-to-side slope, and an operator-presence system locks out the power train and hydraulic system to avoid machine movement when the operator is entering or leaving the cab, assisted by redesigned steps, handles and guardrails. An available visibility package includes mirrors on the lift cylinders and a ROPS-mounted camera system with a color monitor mounted near the rear view mirror.

In line with the improvements made to the D11T dozers, the D9T also features EAS, cooling system enhancements, and the OK-to-Start system.

Liebherr, Volvo: High-tech Performance, with Economy
Last year’s CONEXPO/CONAGG construction equipment exhibition in Las Vegas, Nevada, provided a stage for OEMs offering machines in the lower range of potentially useful capacity for mining applications to highlight their latest models. Liebherr, for example, which lays claim to the title of building the world’s largest hydrostatic-drive dozer and wheel loader, showcased its flagship PR764 Litronic, a 422-hp (310-kW) dozer with an operating weight of approximately 116,150 lb (52.5 metric tons).

As with all its hydrostatic-drive machines, the PR764’s diesel engine provides power to variable-displacement pumps and motors in closed circuit. According to the company, this stepless system allows the dozer to constantly provide an optimum drive ratio for any dozing job, including heavy-duty ripping. Because the engine always operates within its optimum rpm range, fuel consumption is reduced, engine wear is decreased and the low engine speed provides a quieter running machine.

The PR764 Litronic has the same profile and ergonomic features common to all Generation 4 Liebherr dozers. With a redesigned operator’s cab and sloping outer edges, it provides the operator with high visibility of the working area as well as the blade and rear ripper. The dozer also features demand-controlled cooling, wear-free braking via the hydrostatic drive system and a long list of options.

In a similar vein, a characteristic feature of Liebherr’s range of large wheel loaders is the optimized hydrostatic drive concept, based on two directly coupled hydraulic motors of different sizes, each with a separate clutch. Because at least one of the two motors is active when the wheel loader accelerates and decelerates, the loader can adjust to any working condition regardless of travel speed required and without the need for the operator to shift gears.

With an operating weight of 69, 180 lb (31 mt) the L586 Litronic is the flagship of Liebherr’s wheel loader line and is the largest wheel loader in the world with hydrostatic drive. The L586 displayed at Las Vegas had a 7.8 yd3 bucket with a v-pattern overflow plate and teeth. The exhibit model was also equipped with a rear collision guard, undercarriage protection and twin LED work area lights at the front and rear. Other equipment included an audible warning signal when reversing and camera monitoring of the area behind the vehicle. The L586 is powered by a Liebherr six-cylinder, turbocharged diesel engine with a charge air intercooler, and develops 340 hp (250 kW).

Volvo Construction Equipment does not have a dozer product line, but offers a wide selection of wheel loaders, with the L350F at the top of the line’s payload rating range. When introduced several years ago, Volvo CE reported that the new model provided an 18% increase in productivity and 46% better fuel economy over its predecessor, when tested in load and carry operations. The source of these improvements, said Volvo CE, resided in the combination of the L350F’s new Tier 3/Stage IIIA Volvo engine, stronger hydraulics, an improved lift arm, a new transmission with lock-up and new axles.

The L350F’s Volvo D16E engine produces most of its 532 hp (397 kW) and torque at low engine speeds, reducing the need for over-revving as well as providing better fuel economy, reliability and low noise and emissions. The engine is mated to the latest transmission from Volvo—the HTE400—with automatic lockup in third and fourth gears. The transmission features automatic power shifting that offers a selection of shift programs to suit the application as well as operator work style. The system also can be activated to automatically downshift to first gear, leaving the operator only having to select between forward and reverse gears.

Stopping power comes in the form of outboard-mounted wet disc brakes with oil cooling. Powered by a hydraulic dual circuit brake system, the parking brake automatically applies when the engine is switched off or if brake pressure too low. Brake condition can be monitored by wear indicators on each hub and a brake test can be done from inside the cab.

The load sensing hydraulics system on the L350F also were improved, with variable displacement pumps providing exact flow and pressure on demand. Bucket capacity for the L350F ranges from 8.1 to 16.6 yd3 (6.2 to 12.7 m3). Breakout force is rated at 106,290 lb-ft (472.8 kN).

The L350F’s lift arm features improved geometry that is claimed to provide good rollback angles as well as better attachment visibility. The loader also can be specified with boom options: the long boom gives additional dump height while a Boom Suspension System features heavy duty shock absorbers that reduce bucket spillage and allow faster, more comfortable, work cycles.

East Meets West in the Dozer Market
LiuGong Machinery Corp., Liuzhou, China, recently finalized an agreement to acquire Polish heavy equipment manufacturer HSW (Huta Stalowa Wola) and its distribution subsidiary, Dressta Ltd. The transaction is LiuGong’s first outright acquisition outside its domestic market.

HSW manufactures bulldozers, loaders and other crawler machines, and is one of only seven manufacturers worldwide producing a complete line of bulldozers from 74 hp to 520 hp. The Polish government, which owned HSW, had agreed in principal to sell to LiuGong earlier this year with the signing of a preliminary enterprise acquisition agreement in Beijing, China.

The roots of HSW/Dressta earthmover technology can be traced back to 1972, when HSW entered into a licensing agreement with the U.S. agricultural equipment builder International Harvester, which had formed a Construction Equipment Division in the mid-1940s and was eager to expand market scope for its dozers and loaders into Eastern Block countries. International Harvester, however, encountered rough economic waters in the early 1980s and the construction division was acquired by Dresser Industries, which later struck a joint agreement with Komatsu for manufacture of dozers, loaders and other equipment. Komatsu took control of the entity in the mid-1990s and carried on the longstanding arrangement with HSW, eventually establishing Dressta as a joint venture—and brand name—for product development and marketing of equipment produced at HSW’s facilities. Komatsu’s participation in the venture ended in 2005.

LiuGong’s acquisition of HSW is a strategic step for the Chinese company, which has a stated goal of becoming a top-ten construction equipment manufacturer by 2015. The HSW transaction, according to LiuGong, opens an avenue to obtain core technologies that will help it advance some of its product designs, supplements LiuGong’s product lines, provides a manufacturing and logistic footprint in Europe and expands LiuGong’s penetration into market and product segments.

LiuGong currently offers a full line of construction equipment that includes wheel loaders, bulldozers, skid steers, forklifts, motor graders, excavators, and mining trucks, among others. The company sold 75,000 machines in 2011 and has one of the largest global dealer networks of any of its Chinese competitors, consisting of nearly 280 dealers in more than 95 countries, supported by nine subsidiary offices and 10 parts depots.

HSW was established in 1937 and builds dozers at its plant in southwestern Poland. HSW also produces wheel loaders, loggers, pipe layers, conveyer belt shifters, motor graders and machines customized for landfill applications, also for global markets.

David Beatenbough, currently vice president of research and development for LiuGong, has been named chairman of the board of the new entity, LiuGong Machinery (Poland) sp z o.o. Beatenbough commented on how HSW will fit into LiuGong’s plans and product lines: “We will acquire proven technology within the bulldozer segment, as we will now own all the technology and designs, including undercarriages and driveline components,” he explained, adding that LiuGong will benefit from HSW’s experience with large machines, and from HSW’s plant location in central Europe—closer to European customers.

LiuGong intends to move rapidly to integrate processes and production. A talent exchange will bring Chinese engineers to Poland, and send Polish engineers to China for training. The first fast-track project will be an investment into production line equipment and retooling at the Podkarpackie plant, enabling it to produce LiuGong excavators and wheel loaders. LiuGong also will quickly leverage the combined distribution network to bring the expanded product line to dealers—HSW products to LiuGong dealers, and LiuGong products to HSW/Dressta dealers. Relative to brand names, Beatenbough said, for the near term all three brands will be retained in certain markets.

The largest dozer model in the Dressta line is the TD-40E Extra, powered by a Cummins QSK19 Tier 3 engine delivering 515 net hp at 2,000 rpm, linked to a transmission that provides six forward and six reverse speeds. Equipped with a semi-U blade and single-shank ripper, the TD-40E Extra weighs approximately 67.7 metric tons (149,000 lb), which makes it about two tons lighter than a Komatsu D375A and more than a ton heavier than a Cat D10T, according to the company. Capacity when equipped with a full-U blade is 22.8 m3.

Dressta said it has engineered the dozer’s hydraulic control system with advanced solid-state electronic circuitry to provide an electro-hydraulic system in which all control functions are activated by movement of the joystick or by selecting control buttons on the face of the joystick. The joystick control handles up- and down-shifting of the transmission, low or high range selection of left and right track drives or full-power geared turns.

A rear platform located below the fuel tank aids in refueling, air-conditioning filter changes and cab rear window cleaning to enhance serviceability. Maintenance includes a 500-hour oil change interval. The cab is sealed and has a built-in air-recirculation system. An air-suspension operator’s seat swivels at an angle to provide better visibility of the ripper when necessary.

Dressta’s largest wheel loader, the 92,000-lb (41 650-kg) 560E Extra, also is powered by a Cummins diesel, in this instance a 427-hp (319-kW) QSX15. Available in both standard boom and high-lift configurations, the loader offers bucket capacity of 7.5 yd3 (5.7 m3) in the standard version and 7 yd3 in high-lift. Depending on bucket style, dump clearance at maximum height ranges from 10 ft 11 in. to 11 ft 6 in, (3.34 m to 3.59 m); breakout force also varies with bucket style, ranging from 71,149 lb to 78,950 lb (318 kN to 351 kN).

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