THE ARMATURE FRAME 



61 



generator, drawings of whose armature spider are given in Fig. 

 59, only one row of spider arms is employed. 



In machines in which, owing to small size or high speed, or 

 both, the internal diameter of the armature laminations is small, 

 the armature spider with arms is replaced by a sleeve carrying the 



FIG. 57. Photograph of Armature Spider of large Generator. Vickers, Sons & Maxim. 



armature core plates. An instance of this practice is given in 

 Fig. 60, which shows the sleeve of the armature of a 117 h.p. 

 gearless railway motor. A related practice consists in assembling 

 the armature core plates directly on the shaft, as in the case of 

 the 27 h.p. railway armature illustrated in Figs. 61, 62, and 63. 

 These last two methods afford much more limited facilities for 

 ventilation of the core, and it is usual, as in the last instance as 

 may be seen from the figure to punch out apertures in the core 



