Coal Age

FEB 2012

Coal Age Magazine - For more than 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.

Issue link:

Contents of this Issue


Page 32 of 59

support equipment continued new oil-to-air hydraulic-oil cooler uses similar construction, and a hydraulic variable-demand fan uses less power, reduces fuel con- sumption 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 fea- ture 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 sys- tem locks out the power train and hydraulic system to avoid unin- tentional 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 lubrica- tion 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, 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 exhibi- tion in Las Vegas, Nev., provided a stage for OEMs offering machines in the lower range of potentially useful capacity for min- ing applications to highlight their latest models. Liebherr, for exam- ple, 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 con- sumption 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 February 2012 Liebherr PR764 Litronic dozer. 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 pre- decessor, 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 hav- ing 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. 31

Articles in this issue

Links on this page

Archives of this issue

view archives of Coal Age - FEB 2012