. Electric railway journal . ngine, therefore, would deliver twice the horsepowerof the former and would do about twice as much course, the cost of the machine having double thehorsepower would be somewhat larger than that havingthe lower working speed, on account of the necessity forlarger cables, conductors, switches, etc., but on the otherhand, the cost would not vary anywhere near in propor-tion to the horsepower that was delivered, and the useof the higher speed locomotive would be a very greateconomy. Length of Armature Important In general, the permissible peripheral velocity fo
. Electric railway journal . ngine, therefore, would deliver twice the horsepowerof the former and would do about twice as much course, the cost of the machine having double thehorsepower would be somewhat larger than that havingthe lower working speed, on account of the necessity forlarger cables, conductors, switches, etc., but on the otherhand, the cost would not vary anywhere near in propor-tion to the horsepower that was delivered, and the useof the higher speed locomotive would be a very greateconomy. Length of Armature Important In general, the permissible peripheral velocity forrailway motor armatures is of the order of 7000 ft. perminute, the limit depending somewhat upon the con-struction of the motor. It should be recognized thatany motor is a composite structure, and that the actionof the centrifugal force, which varies as the square ofthe speed, is bound to cause a certain amount of rel-ative motion between the different component parts. Ifthe centrifugal speed is excessive, these centrifugal. ELECTRIC LOCOMOTIVE DRIVES—QUILL-SUPPORTED GEAR USEDWITH NEW HAVEN RAILROAD LOCOMOTIVES forces will be productive of much greater relativemovement than would normally exist, thus making cer-tain the ultimate destruction of the insulation by abra-sion and perhaps by mechanical disruption. There is,of course, no such thing as permanence in a compositemachine, and in the case of railway motors especially,where the variable speeds cause variable forces, the in-fluence of peripheral velocity on the motor life is an im-portant one and cannot be neglected. Therefore, for a locomotive operating within anygiven speed limit and delivering a given horsepower,the limit of peripheral velocity, approximately speak-ing, establishes an absolute limit to the rotative speedof the armature, and this, in turn, roughly establishesthe physical size of the motor, which, of course, can bemade to deliver the most power when the rotative speedis highest. Thus the most desirable c
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