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By nature of the work environment, mecha- nized underground mining can't offer the big-picture visibility of large-scale truck and shovel surface operations, and the open space needed for typical multi-truck loading patterns just isn't available underground. However, the basic elements of surface-fleet equipment selection—such as appropriate size for site conditions, correct pass-match- ing between loaders and trucks, and proper machine configuration for optimal safety, reliability and maintenance—are valid and perhaps even more critical in underground operations, where fleet and individual equipment size and capacities are often constrained by work space limitations. Equipment selection was high on the list of discussion topics during the underground segment of the 2014 Cat Global Mining Forum, held May 1–3 in Tucson, Arizona. Cat's Global Mining product line manager, Jay Armburger, led off by noting that Cat has, since its acquisition of Bucyrus in 2011, focused on developing its under- ground equipment and services portfolio as a core strength for the company. Accordingly, among its recent product introductions are a half-dozen "all-Cat" machines and systems for the underground market, including the R1600H LHD—which just became commercially available—along with the R3000H, which was unveiled at MINExpo 2012 and has since entered the market, and the AD60 mine truck. The com- pany also has developed a Ventilation Reduction Package for underground equip- ment and a new diesel particulate filter, and has indicated that its progress on design and testing of a two-boom development drilling jumbo is proceeding satisfactorily. Measuring Up Underground When it comes to the primary considera- tions for sizing and equipping an LHD, according to Cat's senior product specialist, William Edwards, the main concerns are: • Width and height–What's the maximum width allowable for an LHD in an oper- ation? Take into account not just the dimensions of the machine's usual work- space, but all spaces in which it may have to pass through to relocate. Also, pay attention to the actual height of underground work areas by noting any hanging ventilation or mine-service structures that could interfere with machine operation. • Loading method and bucket selection– Will the LHD be loading trucks or carry- ing to a dump point? Bucket selection should consider the machine's primary use and the characteristics of the mate- rial that will be loaded; a standard buck- et design may work well in many appli- cations, but a high-penetration design will be needed for others. If a high-pene- tration bucket is required, keep in mind that load spillage will be somewhat high- er. The bucket's ground engaging tool (GET) system is another important factor; should it be a weld-on or a mechanically attached system? Wear liners are also available and sometimes mandatory de- pending on the material being loaded— but keep in mind all added-on parts and material reduce bucket payload. • Options–Consider what conditions en- countered at the work site need specific optional equipment, which can range from a choice of open or closed cab styles to remote control-ready configura- tions, or ride-control systems to integrated machine-recovery attachments for strand- ed equipment. A similar approach should be used to size and equip underground trucks, said Craig Johnstone, Cat senior product spe- cialist. What are the drift dimensions? Will trucks be loaded by LHD or chute? What's the density of the material that will be loaded? If trucks are loaded by LHD, will they side- or rear-load? Does the mine lay- out lend itself to conventional dump bod- ies or is an ejector body required? Open or closed cab? And which optional features and accessories will be conducive to improved productivity and safety, such as a payload management system, onboard fire suppression equipment or fast-fill fluid service system, for instance? After the loaders and trucks are pur- chased and commissioned underground, the next challenge is to identify the best approach for extracting maximum produc- tivity from them. When planning any pro- ductivity improvement program, keep two primary issues—cost cutting and increas- ing tons loaded and hauled—in mind, and 46 E&MJ; • JUNE 2014 www.e-mj.com L H D S & T R U C K S Equipment Selection is Key for Productivity in Underground Loading and Haulage Making all the right choices can significantly reduce cost per ton, increase worker safety and minimize required maintenance By Russell A. Carter, Managing Editor The largest loader in Cat's LHD lineup, the R3000H shown here, has the bucket capacity and power to three-pass load the company's largest underground truck, the AD60. EMJ_pg46-55_EMJ_pg46-55 6/3/14 2:04 PM Page 46