Discussion on “operation on the Norfolk and Western railway” (Wynne), New York, Feb. 9, 1916. (see proceedings for February 1916)

A. H. Armstrong: The induction motor has one inherent characteristic, constant speed at all loads, that makes it of doubtful application to the haulage of trains over a broken profile. The speed of the motor can be varied only slightly except by changing its number of poles, a matter of doubtful expediency in its practical application to the operation of a train. We have been educated in steam railroading to expect the flexible speed characteristic of the steam engine, that is, slow running on ruling grade and proportional higher speed on the lesser grades and level track. Railroad practise therefore is more or less crystalized about the flexible speed operation of the motive power, and in adapting the induction motor to train haulage we are going against all previous ideas, and the continued operation of the Norfolk & Western Railroad will be watched with considerable interest as throwing light upon the adaptability of the induction motor to main line service.