Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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HAULAGE shift transmission. The 6 x 4 Haulmax 3900 series can handle payloads from 80- 85 mt in the -D version and up to 108 mt in the bare-chassis -G model. Western Star's 6900XD model also is a 6 x 4 off-and-on/highway dump truck capa- ble of handling a 40-ton payload. The rig is powered by a 500-hp Detroit Diesel engine connected to an Allison seven-speed trans- mission. A dual-circuit air brake system is standard, augmented by a Jacobs com- pression brake; optionally available is an Allison hydraulic transmission retarder. Into the Future Cat's 777G has been upgraded to include a new EPA Tier 4 Final engine platform and improved transmission controls. haulage systems have zeroed in on these issues to promote their own systems, which use smaller, cheaper tires and less fuel- hungry engines than the big rigid rigs. They've also devised trailer-based technol- ogy for reaching the 400-ton-payload range that, until recently, was the exclusive domain of ultra-class haulers. Although the practical range of loading-equipment options is narrower with trailer units, and there are some mine-site conditions that can rule out their use, tractor-trailer sys- tems and their variants offer a cost-effec- tive alternative for many applications. Consequently, they are increasingly finding niches in both mainstream and spe- cialized surface haulage applications. For example, during a recent visit to Western Australia's Pilbara, E&MJobserved; tractor- trailers being used side-by-side with rigid haulers at Fortescue Metal Group's mines to transport iron ore over distances that would pose tire-wear problems for the rigid trucks, which instead are used primarily on short hauls to the crusher, and to carry ore to central dumping points for subsequent transfer to the tractor-trailer haulers. Queensland, Australia-based Power- trans has developed a set of mix-and- match system components that allow users to put together 'road trains'—multiple trail- ers pulled by a Powertrans Prime Mover tractor unit that can handle up to 300 mt total payload, and significantly more by employing their Powertrailer, a heavy-duty, high-capacity haulage trailer equipped with a diesel engine, cooling system, trans- mission and drive axle system, all con- trolled from the Powertrans prime mover. Both the Prime Mover and Powertrailer are equipped with Cummins QSK19 diesel engines. www.e-mj.com Powertrans claims that owning and operating costs of a road train are signifi- cantly lower than large off-highway mining trucks because capital costs are about half the cost of larger units, as are maintenance costs. Powertrans units use readily available OTR light earthmoving tires. As a result, loaded speeds in the order of 55 km/h and unloaded speeds of 75 km/h are possible. In mining applications with haul dis- tances between 10 km and 50 km, Powertrans said its equipment can offer a viable low-cost and flexible alternative to rail or conveyor-based transport, with gen- erally lower infrastructure costs. Fitting into a slot somewhere between the traditional rigid-body trucks and trac- tor-trailer configurations are those offered by builders such as Haulmax and Western Star—trucks that may resemble, at first glance, vocational dump trucks but have been designed to handle the tougher demands of mining. Haulmax offers multi-axle models that are designed to fill dual roles as a mine haul truck as well as a conventional over- the-road Class 8 rig. The drive train is all Caterpillar, with power from a Cat C27 diesel running through a 7-speed power Taking a much larger step beyond conven- tional technology, truck builder ETF has designed a haulage system that begins with a futuristic-looking truck unit with 240-ton-capacity—eventually to be avail- able in a range of payload capacities—and allows users to configure these units either as stand-alone haulers or combined into multi-unit haulage trains that are claimed to be capable of handling up to more than 800 tons total payload. The company also promotes a business model that departs radically from conventional practice. Earlier this year, ETF CEO Eddy de Jongh told E&MJ;: "We believe that capital goods such as our products should be care- fully maintained in order to have the best possible technical availability and produc- tivity against the lowest cost per ton in the industry. Therefore we decided that we will only rent our trucks including an innovative life cycle Maintenance and Repair Contract (MARC) with a guaranteed technical avail- ability of 95% including tires. "This means the customer always knows his cost per ton as we charge him a fixed amount per ton/km during the 90,000 hours (11-12 years) of the con- tract. He does not have to worry about war- rantee claims, spare parts availability and mechanics; we take care of it all. The client can concentrate on mining," de Jongh said. A Powertrans road train carrying a 500-mt payload. JUNE 2012 • E&MJ; 83