Transactions . - 772 ROCK-DRILLING ECONOMICS. drill steel. It fits snugly in the barrel, and is held firmly against ashoulder by the rotating nut E. This is the regular stock rotatingnut, furnished by the Ingersoll-Rand Co. with all No. 18 only change in the other parts of the machine made necessary bythe substitution of this chuck for that used with round steel is in thewater tube, which is a little longer. By the use of this chuck unexpected results were obtained. A fewtests, made with the same machine using chucks for round andhexagonal steel alternately, showed little differen
Transactions . - 772 ROCK-DRILLING ECONOMICS. drill steel. It fits snugly in the barrel, and is held firmly against ashoulder by the rotating nut E. This is the regular stock rotatingnut, furnished by the Ingersoll-Rand Co. with all No. 18 only change in the other parts of the machine made necessary bythe substitution of this chuck for that used with round steel is in thewater tube, which is a little longer. By the use of this chuck unexpected results were obtained. A fewtests, made with the same machine using chucks for round andhexagonal steel alternately, showed little difference in efficiency, thechuck for hexagonal steel making a little the better showing. Theprincipal improvement was in breakage of steel. Whereas with the. Fig. 2.—Separate Parts of Chuck Shown in Fig. 1. round steel the number of pieces broken per month had averagednearly 30 per cent, of those in use, with the hexagonal steel thenumber of pieces broken per month, as shown by a test involving nilthe steel used by 14 machines for a period of eight months, was only1 per cent, of those in use. In addition, repair charges on the drill-ing machines were cut almost in half, because with the new chucksthe miners did not let the hammer pound on the front head inbacking off the machine, as is the almost universal custom wherelug steel is used. It was found, also, that by using a slightly largeramount of water before changing steel no trouble was experienced ROCK-DRILLING ECONOMICS. 773 with drills getting stuck in the hole. In fact, only one piece of steelhas been so stuck during the last 18 months. This chuck has been in general and successful use at the CliffsShaft mine for over 18 months, and the design is offered freely to anywho wish to ma
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
