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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EXCAVATING MACHINERY. 75 axis of the crank-shaft, so as to enable it to start its own cut anywhere, is a feature of the highest importance. The only theoretical improvement which can be suggested is the addition of a self-acting feed to the gear; and this will no doubt be soon done. There are, however, several details in which the machine might be improved. “1. The cutter and cutter frame appear to be unnecessarily heavy, and it is thought that the use of cast steel for these parts might make them both lighter and more handy. “* 2. It should by all means be made to run on the ordinary gauge of the pit. “3. The speed of the pistons is in reality very low. It will be possible to increase this, and thus decrease the amount of feed per revolution, or increase the cutting speed, as may be found advisable.” The writer makes frequent comparison of the Winstanley machine with the Baird and the Gillot machines, which he describes in the following sections. These coal cutters, with their auxiliary appliances and requisite fittings, are described as applied to work, the former at the Elemore Colliery, Durham, and the latter at the Wharncliffe Silkstone Collieries, near Barnsley, Yorkshire, Baird's Coal-cutting Mackine—This machine is driven by compressed air. The air is compressed by the winding engine of the upcast pit, which is now no longer drawing coal. The air-cylinder is 24 inches in diameter and 24 inches stroke. It compresses to 45 lbs. per square inch, and works twenty-four strokes per minute. , The air is compressed into a boiler, with a safety valve loaded to 45 lbs., and is taken down the shaft in 6-inch cast-iron pipes. The same pipes are continued, mostly along the floor of the main waggon way, where they would appear to be somewhat liable to accidents, for about 1000 yards underground, when they are reduced to 3 inches, and finally to 2 inches of flexible tubing, which supplies one single coal-cutting machine. There is, of course, a certain amount of leakage in the joints, and from numerous observations, the results of which were shown to the author, it appeared that the difference between pressure in the reservoir at bank, and that at the machine when working, was 2 Ibs. per square inch. The pipes were nearly cold at the machine. The face on which the machine is working is in the main coal, which at that point is nearly 5 feet thick, and is a splendid seam, with a strong freestone roof. There are about 120 yards of face, divided into six sections by gate roads in the solid, and the coal is being “ brought back.” The machine, Figs. 341 to 343, has one air-cylinder A, 8} inches diameter by 12 inches stroke, which propels the machine and also drives the cutters. The engine runs at about 240 revolutions per minute; but this speed is, as will be observed, considerably reduced by the gearing of the machine, and the cutters themselves appear to move very quietly. The machine is exceedingly compact, and the parts are fairly easy of access; it is covered by a sheet-iron case when at work, to shield the gear from injury, and also to facilitate the moving forward of the rails and sleepers on which the machine runs, It will be observed from the drawings that the gauge of the road is 2 feet 9 inches, which is far broader than the regular gauge of the pit. It is thus necessary to provide a special road, on which the machine runs. This is formed of short pit-rails RR, in 4 feet lengths, fitting into cast-iron sleepers, S S. In consequence of the shortness of the lengths of rails, all the sleepers are joint-sleepers, and the L 2