Fig. 13. Armature Bearings.
Motor Suspension. Two methods of suspending motors flexibly on trucks are in common use. That end of the motor which has bearings on the car axle cannot, of course, be flexibly suspended with regard to the axle; but the other end of the motor can be placed on springs, or rest on a bar supported on springs, as shown in [Fig. 14]. This suspension is commonly called nose suspension. Instead of having a special bar and special springs for the nose of the motor, the nose may rest upon some part of the truck that is carried upon springs. Thus, on the M. C. B. type of swivel truck, the nose usually rests on the truck bolster, and thus gets the benefit both of the bolster springs and of the equalizer springs of the truck. Another general plan of suspension is that known in one form as cradle suspension, and in another form as side-bar suspension. A side-bar suspension is shown in [Fig. 15]. Here a larger percentage of the weight of the motor is evidently taken by the springs than in the case of nose suspension. It is desirable to relieve the car axle of as much dead weight as possible. By dead weight is meant weight resting upon it without the intervention of springs.
Fig. 14. Nose Suspension.
Fig. 15. Side-bar Suspension.
Motors of the New York Central Electric Locomotive. These motors are a radical departure from the usual type of railway motors. The locomotive on which they are mounted has four driving axles, upon each of which is mounted an armature, direct, no gears being used, Figs. [16] and [17]. The motors are remarkable for three special features: The method of mounting the armature, the shape of the pole pieces, and the path of the magnetic flux.
Fig. 16. Longitudinal Section of New York Central Locomotive.
The mounting of the armature upon the driving axle and the motor fields on the truck frame makes it necessary to have flat pole pieces in order that the armature may play up and down as the journal box and axle slide in the guides of the truck frame. The shape of the pole pieces may be observed in the drawing [Fig. 16]. When in the central position there is a ¾-inch air gap between the armature and pole pieces. The magnetic flux is continuous through the fields of all four of the motors. It returns through the cast steel side frames of the truck and two bars placed in the path.