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. 



8^9 



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 



