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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6 , MINING MACHINERY. For the purpose of raising and lowering the rods, “ lifting dogs” are required. This consists of a claw-hook, through the shank of which a ring is passed, by means of which it is attached to the rope. When in use, the claw is placed under the head on the shoulder of the top length of rod, and the latter hauled up or lowered by means of the windlass. The lifting dog is represented in Figs. 32 and 33. Another instrument required for raising or lowering is the “nipping fork” or “tiger.” When the rods have been hauled up as far as the height of the shear-legs will allow, they must be supported in that position while being unscrewed. For this purpose, the nipping fork, represented in Fig. 31, is placed upon the top of the guide-tube beneath the joint in the rod, and the latter lowered till the joint rests upon the fork. In like manner, in lowering, the rods are let down till the lifting dog rests upon the fork; the next offtake is then screwed on, and the lifting dog hanging from the other pulley placed under the shoulder of the top length, and the rods slightly lifted thereby to allow the lower dog to be removed. When only one lifting dog is used, after the first offtake has been removed, a short swivel-head lengthening piece must be screwed on to each subsequent offtake, to afford a hold for the dog. Provided the shutter of the guide-tube be made sufficiently strong, they may be made to fulfil the purpose of the nipping fork. For the purpose of screwing up and disconnecting the rods, a kind of wrench, called a “ handdog,” is required. This instrument is shown in Fig. 30, from which its construction will be understood without description. Rods.—The rods by means of which the excavating tools are worked from the surface constitute a very important part of the boring apparatus. They consist usually of bars of iron 1 inch square, . for boring of ordinary dimensions. Other sections have been employed, notably the circular and the octagonal ; but the greater simplicity of the square section, and the advantage which it possesses of allowing the application of keys and spanners to any portion of its length, have caused it to be preferred to the more complex forms. The ordinary forms are shown in Figs. 22 and 23. The rods are generally made up of 10 or 15 feet lengths, and the several lengths of rod are connected by a screw-joint. Other modes of connection have been employed, but all have failed in practice, some for one reason and some for another, leaving the screw-joint in universal use. All the joints should be identical in every respect, so that any two lengths may be connected together; and in making up the rod, care should be taken always to have the socket on the lower end of each length, to prevent rubbish from being jammed into it. The enlarged portion at the joint serves as a point of support to suspend the rods from during the operations of raising and lowering. A grave objection to the employment of iron rods for deep borings is their great weight. Two methods have been proposed of overcoming this difficulty: the first is the substitution of wooden rods for iron ones when the depth is great. Such rods, with their iron connections, lose the greater part of their weight in water, and thus are not exposed to the danger mentioned. They have been successfully employed in many instances. These rods are made of sound, straight-grained pine, in lengths of 25 and 35 feet, have a square section of not less than 2: inches side, with the angles slightly planed off. They are connected by iron screw-joints in the same manner as the iron rods, each end being provided with an iron joint-piece forming a socket into which the rod is bolted, as shown in Fig. 23, A fatal objection to wooden rods for small borings is the necessity for a large section. Less than 2 inches side could not be used, and for great depths 3 inches and 4 inches would be required. But when the bore-hole