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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1875 edition. Excerpt: ...or drum upon springs, but even when this is done the extra strain will be very considerable. The weight of the chain or rope itself must be taken into account when any considerable length is used, and this too will be much greater with chain or hemp rope than with wire rope. Indeed, for deep pits the use of chain would be forbidden by this consideration alone, as a chain of 300 fathoms long, capable of working with a load of 24 cwt., would itself weigh nearly one ton, while a steel-wire rope of the same strength would weigh only 750 lbs. To relieve the winding engine, and to enable it to overcome the weight of a long length of rope, the size of the drum is made to vary, or the speed of winding at first is reduced. This may be effected either by using a conical winding drum, or by using a flat ropo and causing it to wind upon itself. CHAPTER XIV. MACHINERY FOR RAISING STUFF. 105. The Tackle.--The first machine used in mining operations for raising ore or deads is usually the tackle or windlass, shown in fig. 53. This is so simple that it scarcely needs a detailed explanation, but as it is usually made on the spot by the mine carpenter, a few words may not be out of place. The carpenter selects two pieces of "half-timber" a a long enough to reach across the shaft, and strong enough to bear the weight. These are called the "bearers," and they are afterwards planked over, except the small space required for the kibbles. In the middle of these half-timber bearers the uprights b b, made of planks from 10 to 12 inches wide, 4 feet 6 inches long, and 1 to 1J-inches thick, are morticed. In the upper end of each upright a slot, about 10 inches long and 1 inches wide, is cut, and the bottom lined with iron, to reFig. 53. ceive...
| ISBN-13 | 9781152570641 |
|---|---|
| ISBN-10 | 1152570641 |
| Weight | 0.30 Pounds |
| Dimensions | 9.00 x 6.00 x 0.20 In |
| List Price | $14.14 |
| Format | Paperback |
|---|---|
| Pages | 84 pages |
| Publisher | |
| Published On | 2010-01-01 |
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