Contents of Engineering & Mining Journal - FEB 2012

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SUPPORT EQUIPMENT
tions. However, it does offer a wide range of performance, ergonomic and applica- tion-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 upgrad- ed 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 geographi- cal 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 cool- ing package that uses a two-part radiator with aluminum bar-plate cores which con- tribute to durability, efficient heat transfer and corrosion resistance. The new oil-to- air hydraulic-oil cooler uses similar con- struction, 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 automati- cally 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 effi- ciently 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 automati- cally controls the blade during the carry segment. A new operator-presence sys-
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Caterpillar D11T dozer.
tem 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 actuat- ed 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 sys- tems, 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, han- dles and guardrails. An available visibility package includes mirrors on the lift cylin- ders and a ROPS-mounted camera sys- tem with a color monitor mounted near the rear view mirror.
In line with the improvements made to the D11T dozers, the D9T also fea- tures EAS, cooling system enhance- ments, and the OK-to-Start system.
Liebherr, Volvo: High-tech Performance, with Economy Last year's CONEXPO/CONAGG construc- tion equipment exhibition in Las Vegas, Nevada, provided a stage for OEMs offer- ing machines in the lower range of poten- tially useful capacity for mining applica- tions 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 operat- ing 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 with- in its optimum rpm range, fuel consump- tion is reduced, engine wear is decreased and the low engine speed provides a qui- eter running machine.
The PR764 Litronic has the same pro- file 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
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