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room-and-pillar mining continued Eickhoff continuous miners. The two underground sections of the mine have an annual output of approximately 1.2 million metric tons run-of-mine (RoM) coal which is extracted by 107 under- ground and surface personnel operating two continuous miners. Access to the No. 2 seam is done via a 50-m deep box cut. Initially the mine developed this 3- to 3.5-m seam along the bottom of the syncline in a north- easterly direction. To access further reserves lying to the northwest of the syncline required uphill mining at a gra- dient of about 9° over a length of 520 m or 34 pillars. In certain areas the Eickhoff continuous miner had to cut uphill on inclines of more than 10°. Typical room- and-pillar mines in steep seam mining applications advance in the dip direction of the seam [AUSIMM 2009, pp.325] instead of the uphill direction. This performance is proof of the CM2's engineering and hydraulic system, and how an operator can rely on it when it comes to challenging mining conditions. References 2009 AusIMM, AustralAsian Coal Mining Practice, handbook published by AusIMM, Carlton, Australia. 2009-1/2 Fecht, N., Hydraulisch elegant statt mechanisch ("Hydraulically elegant instead of mechanical"). Paper published in FLUID 1-2/2009, Verlag Moderne Industrie GmbH, Landsberg, Germany. The crew—the machine—the outcome. ling through dips. Speed and torque can be adjusted to the individual mining condi- tions by setting the minimum displace- ment at the motors. In normal tramming mode at 10 m/min, the torque is sufficient to climb up very steep roadways as described later on. Experts optimized hose cross sec- tions, fittings' shapes and found best hosing for minimum bending in order to reduce energy dissipation due to inner friction down to an inevitable minimum. Uphill Mining at Halfgewonnen Halfgewonnen Colliery is a room-and-pil- lar coal mine owned by Sudor Coal and the 188 www.coalage.com underground workings are operated by the STA Coal Mining Co. The mine is located 20 km north of Bethal in South Africa's Witbank-Highveld coalfield east of Johannesburg in Mpumalanga. This coal- field is characterized by flat to slightly undulating seams that are penetrated by sills and dykes up to several meters thick. In some areas tilting and vertical displace- ments occur [Jeffrey 2005, pp.95-97]. The coal deposit comprises four seams which form a syncline in this area. The life of the mine amounts to about 15 years according to its current mining leases. Ever since the mine started operating in October 2006 it has successfully used 100th Anniversary Special Issue 2005-02 Jeffrey, L.S., Characterization of Coal Resources in RSA–The Journal of the Southern African Institute of Mining and Metallurgy, SIMM, Johannesburg, RSA. 2003 Renius, K.Th., Hydrostatic Transmission for Mobile Machines ("Hydrostatische Fahrantriebe für mobile Arbeitsmaschinen"). Paper at VDI conference Transmission Concepts for Off-road Purposes ("Antriebssysteme für Off-Road-Einsätze"). VDI Verlag GmbH, Düsseldorf, Germany. 1998 Rydberg, K.-E., Hydrostatic Drives in Heavy Mobile Machinery—New Concepts and Development Trends, SAE Paper No. 981989, SAE, Warrendale, USA. Author Information Dr. Lange is the product manager for Eickhoff's line of continuous miners. August 2012