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Page:Popular Science Monthly Volume 89.djvu/843

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Popular Science Monthly

��A Danger Signal Used to Direct Attention to Overhead Perils

THE sign in the accompan\ing illustra- tion has two uses. It consists of a hea\y steel plate, enameled, with a red background and white letters, carrying its warning. When electrical machinery with high-pressure currents is being tested, this sign is placed near the apparatus and the words "High Voltage, DANGER" appear. When the danger is overhead, as when overhead wires are being repaired or tested, or when a crane moving loads which might spil or collapse, the sign is placed within the danger zone and a little sheet-metal flap, fixed to the top of the sign, is dropped down showing an arrow pointing upward. The arrow stands out vividly so that anyone passing would not fail to look up as directed, from curiosity if for no other reason, before proceeding. By reversing the small metal flap the sign may be made to display simply the one word "Dan'GER."

���A heavy steel plate used to direct attention upward when [the danger is from wires overhead

��A Locomotive Side-Frame Which Weighs Nearly Seven Tons

ALL passenger and freight engines need in their construction what is known generally as a locomoti\e side-frame. On each side of the engine one of these is used; it assists in forming the main framework on which the superstructure is built.

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Until about twenty-fi\e years ago, side- frames were usually forged — a slow and difficult process. Now the cast-steel frame is used. This is made by pouring molten steel into a sand mold. This, after cool- ing, is removed from the surrounding sand of the mold, and, after cleaning, is carefully annealed in an annealing furnace to make the mass of steel homogeneous.

With the constant growth in the size of the modern locomotives the length and k of the locomotive-frame has so increased, until now frames ire made that twenty years ago would have been con- sidered impossible. When the one in the illustration was made it was the largest one recorded, measuring forty-one feet seven inches in length and weighing about thirteen thousand two hundred and fifty pounds. The metal is six inches thick. The fi\e openings in the bottom of the frame are for the dri\ing boxes into which the axle ends go which carry the driving wheels. There are fivedriv- ing wheels on each side. As steel cools it shrinks, so that about thirty-three per cent more steel is needed to pour a casting than is found in the final product. This extra metal is taken up mostl}' b}' sinkheads on the castings which act as fountains or feeders while the casting is cooling. These are cut off and remelted and used in making more steel.

���This gigantic side-frame measures forty-one feet seven inches in length. The five openings in the bottom are for the driving wheels, five of which are provided for each side of the engine. It was molded in one piece by the new cast-steel process. The steel shrinks on cooling, so that thirty-three percent more molten steel, by volume, must be poured in the mold than appears in the finished product

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