YORK, DECEMBER 235, 1880. [NEW SERIES. ] (PosTaGE PREPALD.] AMERICAN INDUSTRIES,—N 0. 63. | only the piston should feel the shock of concussion. Of The Rand Little Giant rock drill is the result of many course the piston must be so arranged as to make a variable years of experiment for the… … , would tend to loosen the bar by turning the jack screw in but it should first of all be simple in construction and strong THE RAND ROCK DRILL the nut; to prevent this a lock uut is used, which keeps the in every part, the parts, as far as possible, being so arranged |-moval of resistance. which…
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