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13 this reduces specific energy required for cutting

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Unformatted text preview: ssure up to 700 bar can make significant reductions in pick cutting forces.13 This reduces specific energy required for cutting and make of dust. 10.7 PROCEDURE OF DRIVING BY THE HEADING MACHINES Least delays are the key for success of the operation. In order to achieve better utilization, 20–25% time during the day, can be allocated for the maintenance. The heading machines also operate in a cycle, whose duration is a function of length of unsupported roof, or the roof that can be allowed unsupported. It varies from face to face. There are different ways to excavate, as shown in figure 10.6.9 ● ● ● ● Excavating the perimeter first and then the central part, if the strata are friable. Ripping bottom first then the upper part to take advantage of undercutting. It gives better advance/output rates. If different bands or layers of the strata are encountered, then soft band can be attacked first and the other once afterwards. If the roof rock is weak it is better to attack the central portion first, and then to rip the sides of the face/working. 10.8 AUXILIARY OPERATIONS Genera...
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