Coal and metal miners' pocketbook of principles, rules, formulas, and tables .. by International Correspondence Schools

Author:International Correspondence Schools
Language: eng
Format: epub
Tags: Mining engineering, Mining machinery
Publisher: Scranton, Pa., The Colliery Engineer Company
Published: 1900-03-25T05:00:00+00:00

adaptation to the varying conditions of a coal seam. When the face cleats are Avorking ftee and the coal is very soft, it may be necessary to drive " end on." The end-on method is best adapted to a very heavy roof pressure, wbile for a light roof pressure the short-horn method assists in breaking the coal. If the " face " cleats are free and the coal breaks readily along them, and. it is reasonably hard, the long-horn method is adopted, for when the coal is undercut it needs more support than it gets firom the cleats, and its weight must be thrown somewhat upon the end cleats. '•Face on" is adopted when the face cleats are not as tree or numerous as the butt cleats. Unless the coal at the face receives sufficient support, the undercutting or bearing in cannot loe thoroughly done, or else tlie amount of spragging and tlie risk to the miner are increased. When the end cleats are less pronounced and numerous, and the roof pressure

grreat, the coal will probably break better by carrying wide breasts upon the ends of the

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.