Coal Age

FEB 2012

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support equipment continued 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 counter- weight 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 met- ric tons) payload. Komatsu D375A-6 dozer. 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 rip- ping 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 con- nection point of the lift cylinder and blade improve machine relia- bility 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 insulat- ed 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 unin- terruptible power source in the cab that allows radio communica- tion 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 mainte- nance, and Jackie D. Haney, product marketing manager for min- ing-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 & 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) 30 Caterpillar D11T dozer. February 2012 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 Incli- nation 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-effi- ciently 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 emis- sions 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

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