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Results 11 - 19 of 19
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8/1/2006 - Conference papersThis paper explores the history of longwall shield design over the past 25 years. It also addresses questions such as whether two-legged designs are better than four-legged shields and whether setting pressures should be set as high as possible.
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8/1/2002 - Conference papersA high percentage of longwall shields, which provide ground control in mines, operate well below the rated support capacity due to hydraulic malfunctions. NIOSH developed a computer program to identify shields not performing to rated specifications.
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6/1/2001 - Conference papersA series of controlled laboratory tests were conducted in a test stand simulating shield dust entrainment to evaluate changes in airborne respirable dust levels at different air velocities.
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6/1/2001 - Conference papersThe purpose of this paper is to set goals for the future generations of longwall shields.
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2/1/2001 - Conference papersLaboratory test to simulate dust liberation during shield movement were conducted.
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8/1/1998 - Conference papersThis paper examines the operating principles of hydraulic cylinders and discusses issues pertaining to setting loads, support stiffness, yielding behavior, errors in assessing support loading, and hydraulic failure mechanisms and how to detect them.
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1/1/1993 - Reports of InvestigationsThis report investigates the removal of gate road chain pillars in conjunction with longwall retreat mining. The objective was to determine how the pillars, supplemental support, and entries were affected by the longwall abutment pressure.
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1/1/1992 - Information CircularsThis report examines shield design, operation practices, and the consequences for using high-capacity shield support systems. An optimization goal is to minimize support loading by using an active shield setting force compatible with strata behavior.
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1/1/1992 - Reports of InvestigationsRoof and floor contact pressure provided by the interaction of a shield with the surrounding strata are examined. Controlled forces were applied to an 800-ton two-leg shield using a mine roof simulator.
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Content source: National Institute for Occupational Safety and Health, Mining Program