. Railway mechanical engineer . - for the proper operation of the furnace are in-stalled upon the switchboard, together with a pyrometer bymeans of which an accurate record of the furnace temperatureis obtained at all times. The operation of the furnace is simple. Upon closing themain switch, current at full rated voltage is sent throughthe resistor material in the trough which is a poor conductorof electricity, especially when cold. The resistance to theflow of current transforms the electrical energy entering thetroughs into heat energy and the furnace begins to heat to the negative t
. Railway mechanical engineer . - for the proper operation of the furnace are in-stalled upon the switchboard, together with a pyrometer bymeans of which an accurate record of the furnace temperatureis obtained at all times. The operation of the furnace is simple. Upon closing themain switch, current at full rated voltage is sent throughthe resistor material in the trough which is a poor conductorof electricity, especially when cold. The resistance to theflow of current transforms the electrical energy entering thetroughs into heat energy and the furnace begins to heat to the negative temperature coefficient of the carbon orgraphite resistor material it becomes a better conductor thehotter it gets so that as its conductivity increases its resistancedecreases and more current flows. This fact is duly indi-cated ijy the instruments on the board and when the powerinput tends to become excessive it is cut down and held con-. Fig. 3—Dipping the Axles in the Cooling Tank Slant by lowering the voltage by means of an operating trans-former provided for its control. The time it takes to bringthe furnace up to desired temperature depends of course enwhether the furnace is cold or already partially heated andupon the process to be performed. At the plant of the Laclede Steel Company the raw ma-terial for axles is received in the form of .steel billets run-ning around .35 to .50 per cent carbon. These billets areforged to the proper shape and size. After being allowedto cool in the air they are loaded in a cradle on the car ofthe electric heating furnace. It should be noted from Fig. 2that each separate piece is so loaded that there is free airspace completely around it. This is to enable the heat toreach all parts of each piece and penetrate uniformly. Whenproperly loaded the car is run into the hot furnace and theaxles allowed to .soak for a certain definite time. After heating at about 1,600 deg. F. the car
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
