The Mechanical Handling and Storing of Material

CHAPTER XIII COAL FACE CONVEYORS Mechanical appliances for removing coal and other minerals from the working face are very old, and some crude devices were used, it is believed, even by the ancient Egyptians. The last decade witnessed great activity in this direction in consequence of the thick coal seams becoming exhausted, and thin seams can only be economically worked by coal-cutters and coal face conveyors in one form or another. The advent of the mechanical coal-cutter in connection with the long wall coal face makes the face conveyor not only more applicable to coal getting, but almost indispensable. The Eight Hour Act has further emphasised the importance of mechanical appliances for economical working under ground. Space does not permit of going fully into this vast subject—sufficient to fill a large volume by itself1—so it is only proposed to give a general idea of the different systems without entering into the application of the machine in the mines, as this would be beyond the scope of this book. There is also a great similarity between some of the appliances. The most important are mentioned, and references are given for those who wish to be more fully informed as to where fuller descriptions are to be found. The oldest methods were probably a kind of sledge, which was dragged along the working face to the loading point by ropes and blocks, or a skip travelling on a rope, which was stretched along the roof of the seam, and on which the skip was pushed along by hand and tipped into the tub in the gate. This was used in the eighties. Isolated appliances, the outcome of the inventive genius of the coal getters or the engineer, have enjoyed only a local popularity, and none of these has become established as an economical labour-saving appliance. A detailed description of the manual conveyors would have only historical value ; suffice it to say that they consisted of a small tram or a long low receptacle with a capacity of a few hundredweights, which were applied in some thin seams with varied success. As the capacity is very limited, this method is only applicable in seams where the absence of suitable driving power or some other circumstance preclude power-driven devices. The systems now in use may be divided into four classes : A. Appliances in which the coal is carried in a receptacle ; B. Appliances in which the coal is carried on an endless band ; C. Appliances in which the coal is dragged along in a fixed trough by a chain or scrapers; D. Appliances which propel the material either by a simple reciprocating motion down an inclined trough, or by a more complex motion on the level, and even slightly uphill. Class A.—Appliances in which the coal is carried in a receptacle. Appliances under this head generally involve small capital expenditure, and consist of one or more small coal tubs upon rails running in front of the coal face. At the gateway a bridge is formed and a full-sized tub placed underneath, which receives the contents of the smaller tub or tubs through an outlet controlled by a slide. The small tub is made with sloping sides and mounted upon axles, which allow the bottom of the tub to approach close to 1 A volume of over 300 pages, with 274 illustrations and 5 plates, has been written exclusively on this subject by Arthur Gerke, of Bochum, 1913, entitled “ Ueber Abbauförderung.” 159