The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . nd Safety Appliances—The Deep-est Shaft in the World—Methods of Mine Timbering. The most important machine connected with a mine isthe hoisting-engine, which is usually a combined steam-engine and hoist. There are ts\0 common styles. ThePennsylvania and Lake Superior mines mostly use hoistshaving very large drums, around which is wound, in spiralgrooves, the wire rope that supports the cages. These aredirectly connected with the engines, and controlled bypowerful brakes, usually of the
The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . nd Safety Appliances—The Deep-est Shaft in the World—Methods of Mine Timbering. The most important machine connected with a mine isthe hoisting-engine, which is usually a combined steam-engine and hoist. There are ts\0 common styles. ThePennsylvania and Lake Superior mines mostly use hoistshaving very large drums, around which is wound, in spiralgrooves, the wire rope that supports the cages. These aredirectly connected with the engines, and controlled bypowerful brakes, usually of the band type, passing nearlyaround the large drum, on which they take hold by fric-tion. An objection to this type is that the drums arenecessarily heavy, and acquire a momentum like a fly- 258 WONDERS OF MODERN MECHANISM. wheel, which renders them hard to stop and slow in start-ing. The other style, more used in the Western States,makes use of a comparatively light reel and a flat rope,arranged to wind over and over on itself within a smallspace, so as to avoid the fly-wheel eflect as far as ; ^•?\Tfi^^--^ % iJu- ;; \\ ••-•• // A JUNE REEL-HOISTIXG ENGDTE. In the larger plants air-brakes are made use of, very simi-lar in construction to those employed on railway making calculations for mine-hoists the length of ropeis an important factor. A depth of three thousand feetwill require a size and \veight of rope different from thatin a fifteen-hundred-foot mine, where the hoisting capacityis to be the same. For a depth of two thousand five hun-dred feet the size of flat steel rope required would be fiveby three-eighths inches, with engine cylinders twenty incheslong and with sixty inches stroke. For a depth of sixhundred feet the rope would be required to be only half MINING AND MINING-MACHINERY. 259 the size to carry the same load, and the engines of lessthan half the capacity. It is hard to say what a mine-cage usually weighs, as there is so
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Keywords: ., bookcentury1800, booksubjectmachinery, booksubjectmechanicalengi
