Show THE AMERICAN ROTARY DRILL communicated the american rotary tunnel machine development company is building in denver colo a tunneling machine which is designed to bore a circular hole eight feet in diameter in hard rock we have been advised that work upon this machine is being in I 1 pushed as rapidly as the material which enters into its construction can be obtained from several works in the east which make a specialty of shafting springs cutting heads etc and it is expected that these with castings and other parts made in denver shops will be assembled within a few weeks and the machine as a whole given an actual working test As is seen by the illustration in the com banys advertisement the machine has several ram heads in fact ten in number these individual heads are twenty four inches in diameter and are intended to strike about four thousand pound chipping blows per minute the main shaft revolves rotating the cams which with the contact of the capets on the cams pulling back the shafts of each cutting head compresses the strong springs releasing them in quick succession to deliver their powerful blows by a gear from the main shaft the entire machine revolves in the tunnel so that no head strikes twice in exactly the same place and by an ingenious device the wheels on the periphery of the machine are set so that with the revolution of the machine it moves forward or by reversing the position of the wheels the machine can back out the machine is electrically driven by a motor designed for the work intended and this motor is attached to the main shaft in direct connection the main shaft is also hollow through which a stream of water is forced under adequate pressure upon the entire face of the tunnel so as to prevent dust and to be in sufficient quantity to wash the muck back of the machine the writer has in mind a record of 2608 feet of tunnel and drift feet the actual cost co st of which exclusive of management was as follows air drill of a well known type being used labor payroll including cost per running gf t timbering powder caps and fuse wood cords at 5 per cord 63 water 32 coal 06 ties and timbers 06 candles 10 steel rails 22 air pipe and water pipe 45 horse feed 10 steel drill parts oil tools etc 12 total 1102 this work was driven in queenston brown slate and heavy mineral min erali iced talc tafe chist filled with quartz stringers the ground was firm and needed almost no timbering the best weeks record being holes drilled holes re blasted 6 total depth of holes 1478 average depth of holes 5 time used in drilling for week 45 hours average time per shift 2 hours 8 mi powder used pounds candles used 77 pounds water used 40 inches rock extracted for the week cars number of working days 7 shifts 21 number of men 31 average progress per day 1314 feet tunnel advance per week 92 feet expense for the week labor 1 this is certainly good drill practice and rapid rapi d mining but there is a fe feling feeling ling among mining engineers that the present methods are too slow and they are looking fol or t greater speed the object of the american rotary tunnel machine development company is to bring about this desired re suit sul tand and to produce more better and cheap cheal er work than any mining machine which I 1 has ever been invented at the companas comp anys office 58 west second south street salt lake city is a model of the large machine Z t now in process of construction this 1 model expresses more vividly than any photograph or drawing the general idea of the machine and mr 0 G pfeiffer local manager for the company would be pleased to meet all who are interested and especially mining engineers and managers of mining properties |