Transactions . Fig. 4.—Plugger for Drilling Holes. holes to a depth of 15 ft. It is essentially an all-steel drill. The cylinder,for instance, is drop forged, made of special steel, treated and hardenedin the bore. Its most interesting feature is its automatic rotation, whichis shown in the skeleton section, Fig. 7. Fig. 8 is a view of Jackhamersengaged in stoping in No. 15 shaft, seventh level, Osceola Amygdaloidallode of the Calumet and Hecla mine, Calumet, Mich. 1^0 ROCK-DRILLING ECONOMICS. Specifications of Jackhamer. Length, inches 18 Cylinder diameter, inches 2 34 Stroke, inches 2 Steel
Transactions . Fig. 4.—Plugger for Drilling Holes. holes to a depth of 15 ft. It is essentially an all-steel drill. The cylinder,for instance, is drop forged, made of special steel, treated and hardenedin the bore. Its most interesting feature is its automatic rotation, whichis shown in the skeleton section, Fig. 7. Fig. 8 is a view of Jackhamersengaged in stoping in No. 15 shaft, seventh level, Osceola Amygdaloidallode of the Calumet and Hecla mine, Calumet, Mich. 1^0 ROCK-DRILLING ECONOMICS. Specifications of Jackhamer. Length, inches 18 Cylinder diameter, inches 2 34 Stroke, inches 2 Steel used, hollow hexagon, inches V% Size of air hose, inches M Weight, pounds 40 3. The Stoper stoper hammer drill is so well known and so generally used thatfurther description is unnecessary. It is but a few years since this machine. Fig. -Plugger Drills in Operation* at Grand Central Terminal, New York. was invented and its application to general mining work has been veryrapid. Thousands of them are in use. Fig. 9 is a sectional view and shows a stoper in operation. In this particular case a jet discharges aspray of water for allaying the dust. ROCK-DRILLING ECONOMICS. 161 Specifications of Stoper Drill. Piston diameter, inches 2 Piston stroke, inches 4 Length of feed, inches 22 Length of machine over all (closed), inches 52J^ Length of machine over all (extended), inches 743^ Weight, pounds 73 Size air hose, inch M
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
