Abstract
IT is generally admitted that the only real way to increase the prosperity of a coal mine is to increase the output per head of the workers employed. Of recent years great improvements have been made in the methods of the removal of the coal broken at the working face by mechanical conveyors actuated by electric motors. The Metropolitan-Vickers Electrical Company has specialised in the production of motors and control gear for this purpose. In the December issue of the firm's Gazette, an account is given of the many rigorous conditions these motors have to satisfy and the various types of conveyor used in practice. In the belt conveyor the coal is carried on a moving continuous belt. In the shaker conveyor it is conveyed by an oscillating trough, which moves slowly in one direction but has a comparatively quick return. The coal is thus carried forward in the desired direction by a series of jerks. In the scraper conveyor the coal is conveyed by a continuous scraper working in a fixed trough. For each type of conveyor the demands on the electrical motor are different and so also are the arrangements of the electrical control equipment. Graphs are given, showing how the loads on these types of conveyor vary with the time. In the motors ordinarily used, causes of failure arise from the whipping of the shaft and from the ingress of stone dust at the bearings. In the motors described, the roller-bearing at the driving end and the ball-bearing at the opposite end are both constructed in dust-proof ‘housings’. The diameter of the shaft of a Metropolitan-Vickers new 15-h.p. conveyor motor is 2.5 in. and the rotating part is practically indestructible. The progress made in mechanical haulage will greatly diminish the use of animals underground for haulage purposes.
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Electrical Conveyors in Mines. Nature 129, 502–503 (1932). https://doi.org/10.1038/129502d0
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DOI: https://doi.org/10.1038/129502d0