. American engineer and railroad journal . ned between the mold andthe vacuum tank, causing the air in the mold to be drawn out,and at the same time pressiue of any required degree may beapplied to the piston. This pressure bursts that portion ofthe asbestos lining that lies immediately over the hole in thecover plate, and the metal is instantaneously shot into everyportion of the matrix in the mold. Heferring to the engraving, 1 is a chamber under the moldbox, whicli connects with it through the opening 1 a and withthe vacuum tank throngb the pipe 7. The molds are shownat 3, their matrix spac
. American engineer and railroad journal . ned between the mold andthe vacuum tank, causing the air in the mold to be drawn out,and at the same time pressiue of any required degree may beapplied to the piston. This pressure bursts that portion ofthe asbestos lining that lies immediately over the hole in thecover plate, and the metal is instantaneously shot into everyportion of the matrix in the mold. Heferring to the engraving, 1 is a chamber under the moldbox, whicli connects with it through the opening 1 a and withthe vacuum tank throngb the pipe 7. The molds are shownat 3, their matrix spaces at 3, tlie sprue at 5, horizontal linesfrom 3 to 5 representing the channels or gates. The reservoirwith its asbestos lining is seen at 15, witii the metal runner at14 and the piston at l(i. Between the molds 3 and the sides ofthe box, 21, there is shown a loam tamping, 22. Screws 24tapped into the yoke 23 enable the cover or cope to be forceddown firmly on the mold. Ihe use of the rack, pinion andlever, 17, 18 and 19, is clearly SMITU PKESSDRE CASTING MECHANISM. In the words of the patent, the effectiveness of the above-described method and apparatus for the formation of extreme-ly light and sharp castings having a solidity, homogcneousnessand a freedom from blow boles comparable to electro depositedor to rolled metal, is largely attributable to (1) the absoluteisolation of the molten mass from metallic surfaces ; (2) thedisconnection of the molten mass from the molds until the in-stant of inrtow ; (3) the effective removal of air, vapor andgases from the matrix spaces and the pores of the molds priorto and during the infiow by communication with a large andcontinuously exhausted vacutun chamber ; (4) the completehermetical sealing in of the molten metal from the instant ofthe application of the forcing piston. One of the most remarkable features of some of the castingsis what is known as undercutting, which is produced in directly from the pattern withou
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
