Transactions . \:—vi. 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
Transactions . \:—vi. 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
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
