The Elements of Mining and Quarrying (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1903 Excerpt: ... for sinking intermediate shafts (winzes). Occasionally, as for instance at the Long Tunnel, Walhalla. in Victoria, all the hoisting of a mine is done by a compressed air engine. Hoisting by electricity is as yet in its infancy, but already motors of considerable size are employed for winding purposes in mines, and the new engine for one of the shafts of the Gelsenkirchen Mining Company in Westphalia will have a maximum capacity of 2800 h.-p. A winding drum is usually a mere revolving cylinder around which the rope coils itself. An objection urged against the plain cylindrical drum is that it in no way compensates for the change of work required of the engine during the different phases of winding. To make this plain, suppose one end of the rope to be at the bottom of the shaft with the full load attached to it, whilst the other end is at the top with nothing but the empty cage. On starting, the engine has to raise not only the weight of the load of mineral, but also the entire weight of the rope hanging down the shaft, and in deep mines with large cages, this weight is by no means inconsiderable. In proportion as the full cage is raised, the amount of dead weight of rope to be lifted becomes less and less. Eventually the full and empty cages meet; the two portions of the rope then balance each other, and the engine has simply to overcome the action of gravity upon the mineral; later on, the rope of the empty cage is longer than that of the full one, and assists the engine in doing its work. At last, when the load is nearing the top, the drum is feeling the full weight of the rope of the empty cage. Constancy of load is easily obtainable with the cylindrical drum by the simple expedient of adding a balance rope, that is to say, a rope hanging down the shaft...