Collection: Directories and Documents

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Title: A Descriptive Treatise on Mining Machinery, Tools, and Other Appliances Used in Mining - Volume 1 (1877) Collection Type: Directories and Documents Author: George G. Andre Published: 1877 # of Pages: 311 Download PDF: User Login Required Download OCR Text: User Login Required

Date Scanned: 2025-05-04 16:56:34 OCR Software Version #: tesseract 4.1.1 Item Sourced From: PDF First Created: 2025-05-05 01:05:02 Last Updated: 2025-05-05 05:59:57

Digital Copy Held At: Searls Historical Library Location: 161 Nevada City Hwy, Nevada City, CA 95959

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HAULING AND HOISTING MACHINERY. 103 other end is then passed through the loop, as shown in the drawing. The loops are of hemp, one inch in diameter, and are strong enough to draw ten or twelve tubs at a time up a considerable incline. Less labour is required to make the connection in this way than in that last described. In some cases, the rope runs along upon the floor of the waggon way, beneath the tubs. A kind of clamp is then used to make the connection between the rope and the set of tubs. Two of these clamps are shown in Figs, 425 to 429. The construction and mode of action of these clamps will be readily understood from the drawings. The clamp being closed by the lever handle and held by a pin, or by means of the link, the rope is firmly gripped. The set of tubs is connected to the clamp by a short piece of chain. Such clamps are worked by a man who rides in the first tub at the front end of set. Caces.—It was formerly the custom to tip the coal as it arrived at the shaft, into vessels of various forms, in which it was raised to bank. This vessel, being allowed to swing loose in the shaft, rendered it impossible to wind at a high speed. Moreover, it was necessary to adopt some arrangement whereby the ascending vessel was prevented from coming into contact with the descending one, when two were used in the same shaft. This system of winding was very slow and insecure, and in consequence of the jolting occasioned by the vessel striking against the sides of the shaft, both it and the rope were speedily destroyed, Another disadvantage of this system was the delay and the injury to the coal occasioned by tipping it into the vessel at the bottom of the shaft, and by tipping it out again at surface. The system is still in use in Belgium, where the vessel in which the coal is raised is called cuffat, and partially in Staffordshire, where the coal is raised upon skips to be hereafter described. The necessity for raising a large quantity of mineral in a given time, for obtaining that quantity in a better condition, and for providing a system of winding more secure to life and limb, led to the adoption of cages moving between guides. These so-called cages are iron constructions, made to contain one or two or more tubs, which are in this way raised through the shaft with their contents. The tub is run on to the floor of the cage at the bottom of the shaft, and off again when the cage has arrived at surface. Thus the objections to the transfer of the load from one receptacle to another are altogether obviated. Also, as the cages are made to run between guides, they may be raised and lowered at a high speed with perfect safety. In some pits, the load is raised with a velocity of 20 feet a second. The introduction of the cage which is due to Mr. Curr, of Sheffield, must be regarded as the greatest improvement ever effected in the operation of winding. One serious disadvantage attending this system is the great increase of the dead weight to be raised in the shaft. But this disadvantage is much more than compensated by the gain in the directions already pointed out. This additional dead weight remains, however, an important matter to be dealt with by mining engineers, the question being how to reduce this weight to a minimum. Cages are merely receptacles for the tubs, or vehicles in which the loaded tubs are transported to surface and the empty tubs returned from surface to the workings. Their use being merely to travel up and down the shaft, they are not subject to any of the conditions which determine the construction of the ordinary rolling stock. But the conditions prevailing in this case become obvious on reflection. Thus it is clearly apparent that the requirements of a drawing cage are: 1, that its form and capacity shall be such as will allow a sufficient number of tubs to be readily placed in it and removed from it; 2, that its form and mode of construction shall be such as will allow it to run easily along its guided path in the shaft ; and 3, that its mode of construction and material shall be such as will allow the greatest carrying capacity with the least weight of cage.