. The Americana : a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc. of the world . 00 feet per dayof 10 hours. The long-wall machines are of two types,the cutter-bar machine illustrated by Fig. 6,and the cutter-wheel8 machine shown byFig. 7. A cutter-bar machine consists of a steelframe finished smooth on one of the long sidesso as to slide along the face of the coal. It issupported on the bottom on a steel shoe plate,and carrie? jpon the middle portion a powerfulelectric motor, the armature shaft of whichlies lengthwise
. The Americana : a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc. of the world . 00 feet per dayof 10 hours. The long-wall machines are of two types,the cutter-bar machine illustrated by Fig. 6,and the cutter-wheel8 machine shown byFig. 7. A cutter-bar machine consists of a steelframe finished smooth on one of the long sidesso as to slide along the face of the coal. It issupported on the bottom on a steel shoe plate,and carrie? jpon the middle portion a powerfulelectric motor, the armature shaft of whichlies lengthwise of the machine and is gearedat one end to a sprocket which drives thecutter-chain* around a steel cutter-bar* ex-tending at right angles to the frame. Thesemachines are of the under-cutter type, andare capable of making cuts ranging from 38 to50 inches according to the length of the cutter-bar employed. The cutter-bar is carried on aswinging frame, and by means of a lever canbe tilted in its width up or down from thehorizontal position to enable the chain to avoidany especially hard substance by cutting overor under the same. A cable-winding drum or. tttng of these ma- f the mine. A < ut Fig. 7. other similar arrangement, operated by a rachetlever connected with the motor and the drivingsprocket, winds up a wire or chain cable whichis attached to one end of the frame and passesaround a sheave fastened to the front action of this arrangement feeds themachine along the face of the coal. In under-cutting, a jackscrew forces the cutter-bar underthe coal where it is retained by the action ofthe bits on the moving chain, against the coal,without requiring a rail or other contrivanceto keep the machine in position. The averagework accomplished by a machine of this typeis 500 lineal feet of undercutting in one shift. The cutter-wheel machines of this classemploy a cutter wheel in the periphery of whichthe bits or cutters are inserted, instead of achain which travels around
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectencyclo, bookyear1903
