Page:Popular Science Monthly Volume 74.djvu/219

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215
ELECTRIC OPERATIONS OF STEAM RAILWAYS

electric locomotive weighs 100 tons less than the steam locomotive, resulting in the consequent saving in the ton mileage of dead weight.

The operating conditions and the reliability of service are improved in all classes of traffic by the substitution of electricity. The construction of the electric locomotive is far simpler. The steam locomotive comprises fire box, boiler, steam engine and facilities for handling coal and water. The electric locomotive, on the contrary, consists only of the electric substitute for the engine and this substitute has no reciprocating parts. There is consequently less wear and tear and less likelihood of derailment and broken rail. The fire box and boiler are absent as sources of danger in a collision, as are also apparatus for steam or fire heating and oil or gas lighting. Signals are clearer in the absence of smoke and automatic signals are possible, though as yet they are little used. The control of power to trains in sections or blocks is also possible. The number of car miles per train-minute of delay has been nearly doubled on the elevated lines of New York since the electrical operation was inaugurated. Less time is required for clearing and despatching trains, water and coal stops are obviated and less attention is required for light and heat. The electric locomotive is always ready, requiring no time for firing.

As against these several advantages in operating conditions and reliability, there are several disadvantages. The supply of power to all trains from one power house is objectionable from the standpoint that an accident at the power house may stop all trains. Whatever may be said of the steam locomotive in its comparison with the electric motor, the locomotive is self-contained. This danger under electrical operation is minimized by a thorough subdivision of all the power house apparatus. This method of subdivision, however, is not so readily possible in the transmission and conducting systems leading power to the trains and accidents to this portion of the equipment constitute one of the most serious menaces to the continuous operation of an electric railroad. The presence of the third rail or trolley and the transmission line throughout the right of way is in itself a certain source of danger. In a collision the danger of a fire from a third rail in some measure offsets the similar danger from a locomotive fire box. The danger from this source, however, has been overestimated, and the danger of shock from a high voltage trolley is practically eliminated by the modern methods of suspension. These methods consist in supplementing the actual trolley conductor with one or more steel cables for increasing the tensile strength of the overhead construction. The thorough grounding or connecting to the rail of all the supports of the trolley wire ensures that even in the unlikely instance of the breaking of the overhead construction the wire will have no voltage when it reaches the ground. So reliable has this method of suspension come