 Siemens' ac-drive technology provides mining trucks nearly twice the power of the most powerful stand-alone diesel engines. The latest diesel engines operate at about 2050 kW (2750 hp); by comparison, Siemens' ac drives provide up to 4100 kW (5500 hp).  |
Trolley installations using dc drives were popular in the 1980s during the energy crisis, but lost popularity as energy costs dropped in the 1990s. Now this technology, combined with ac-drive systems, is capturing interest as mines look for ways to improve productivity and lower the costs per ton of material moved.
Powering a new Euclid R280 haul truck at Iscor's Grootegeluk coal mine in South Africa, Siemens Energy & Automation claims its ac drive technology can provide mining trucks nearly twice the power of the most powerful stand-alone diesel engines. When linked to an overhead electrical trolley line, the extra power is used to increase production so that fewer trucks are needed to do the same work.
While the latest diesel engines operate at about 2050 kW (2750 hp), Siemens ac drives provide up to 4100 kW (5500 hp). "Only on a trolley line can the full power of the drive system be utilized, increasing speed-on-grade by up to 80% or more," said Walter Koellner, Marketing Manager for Siemens Mining Group. "Depending on the mine profile, this may mean that the same amount of material can be moved with 20% fewer trucks."
Used by Liebherr and Euclid on their "Ultra Class Trucks," Siemens ac drive technology combined with trolley operation lets operators reach productivity records with higher tonnage, higher speeds-on-grade, and further reduced maintenance costs, not only for the diesel engines, but also for the ac electric wheel motors. Additional advantages of "trolley power" include significantly quieter operation, reduced diesel exhaust emissions, and reduced energy costs.
While the new trolley system was designed for 2600 V, a Siemens-patented "diesel boost" circuit allows the system to run on any line voltage, so the system can be installed on existing equipment. At Grootegeluk, where the line voltage is 1600 to 2000 V dc, the system measures line voltage and the controls adjust the trucks alternator output voltage to generate the difference. This all happens automatically within seconds, ensuring a smooth ride for the operator.
 The Vortec 6000 V8 from GM Powertrain includes a symmetrical runner composite intake manifold designed to optimize airflow and allow for enhanced corrosion resistance. |
For 2002 applications, the GM Powertrain Vortec 6000 V8 will be available to several marine OEMs. The Vortec 6000 engine is featured in several GM trucks, including the 2001 GMC Sierra C3, GMC Yukon Denali, and Chevrolet Suburban. With a targeted power rating of 242 kW (325 hp) at 5000 rpm and 500 N•m (370 lb•ft) at 4000 rpm in the pickup range, the 6.0-L engine produces an additional 52 kW (70 hp) and 54 N•m (40 lb•ft) over the 5.7-L. For marine applications, the Vortec 6000 delivers 260 kW (350 hp) at 5200 rpm and 518 N•m (382 lb•ft) at 4400 rpm.
GM Powertrain engineers used the proven small-block architecture as a basis for creating the Vortec 6000 and focused on only those improvements that would provide enhancements to engine torque and power delivery. The engine has a deep-skirt cast-iron block and features aluminum cylinder heads, similar in design to those developed for the 2001 LS6 Corvette V8, which allow for better flow, are 25 kg (56 lb) lighter, and have improved valve-seat durability. They also dissipate heat more quickly, reduce overall cooling requirements, and allow an increase in spark advance without pre-ignition.
Intake and exhaust ports are identical to those in the LS6 head, for an increase in volumetric efficiency. The Vortec 6000 heads have a larger combustion chamber than the LS6 to accommodate the increased engine displacement. New, more durable, multi-layer-steel head gaskets maintain proper heat conductivity with the engine's cast-iron engine block.
A new steel camshaft, unique to the Vortec 6000, is the single biggest contributor to the increase in power. The cam increases valve lift and duration slightly to take full advantage of the increase in volumetric efficiency allowed by the new cylinder head design. Performance improvements are also garnered with the addition of a lower-restriction exhaust system. A coil-near-plug ignition system delivers increased ignition energy, helps reduce emissions, and improves idle quality.
  GM, Fountain Powerboats, and Mercury MerCruiser jointly developed a concept boat, VX6, that features two enhanced Vortec 6000 engines. |
The block has six-bolt main bearing caps, which help in the overall rigidity and the reduction of NVH. A new firing order reduces stress on the internally balanced and counterweighted cast nodular iron crankshaft by 7%.
The Vortec 6000 has alternative-fuel capabilities (compressed natural gas or liquid propane gas) in the heavy-duty models. An advanced coolant-loss protection system protects the engine in the event of coolant drainage, either partial or total. If a loss is detected, the computer limits engine power and allows the engine to run as an air-cooled system, giving the driver a limited ability to find a repair facility or suitable pull-off area.
GM engines that are sold to the marine industry are designed from the beginning to meet both the vehicle and marine customer's requirements. Some of the specially designed marine features for the Vortec 6000 include a symmetrical runner composite intake manifold designed to optimize airflow and allow for enhanced corrosion resistance. The engine is also equipped with a PCV system for emissions control, proven overhead valve technology, and a coil-per-cylinder ignition system that delivers a dedicated spark to each spark plug and improves overall engine performance.
The LS6 inspired aluminum cylinder heads are designed with increased volumetric efficiency for maximum power in this application. An assortment of accessory parts such as electronic throttle control hardware, ECM, sight shield, and related parts will be available in kit form to package the Vortec 6000.
Because about 25% of GM's larger displacement engines are typically sold for marine use, much of the validation on the Vortec 6000 was done using the marine market's more severe test parameters. In one particular test, called the Marine Dock, an engine is run at virtually wide-open throttle for 300 h straight during 60-min cycles (55-min wide-open throttle/5 min idle). According to GM, this testing is more severe than the standard durability testing used for truck applications.
GM, Fountain Powerboats, and Mercury MerCruiser jointly developed a concept boat, VX6, to demonstrate the capability of the newly marinized engine. The VX6 is a competition version of the latest edition 11-m (35-ft) Lightning Sport Boat that features two enhanced Vortec 6000 engines with a total output of 445 kW (600 hp) at 6000 rpm and 680 N•m (500 lb•ft) at 4000 rpm. The VX6 can reach speeds of more than 160 km/h (100 mph).
