CONSTRUCTION OF SQUIRREL CAGE ARMATURES 97 



ends of the spider arms, and it is a good plan to dispense with 

 this whenever possible, as 

 it constitutes a needless 

 obstruction to the venti- 

 lating air. 



In very large rotors, 

 however, a very massive 

 and safe construction is 

 necessary, and the lines 

 indicated in any of the 

 large spiders for con- 

 tinuous-current dynamos 

 given in Chap. I IT. may 

 be followed. As a good 

 deal has already been 

 said about large spiders 

 for continuous - current 

 armatures in that 

 chapter, it is not neces- 

 sary to dwell any further 

 on the matter here. 



Turning now away 

 from the spider, the chief 

 variation in the con- 

 struction of the squirrel 

 cage armatures is in the 

 methods of constructing 

 and securing the end 

 rings of the squirrel cage 

 windings. There are 

 practically no electrical 

 considerations of import- 

 ance in connection with 

 the squirrel cage wind- 

 ings, the only necessity 

 being to make a sound 

 mechanical job of the 

 winding. This is not a 

 difficult problem, and 

 there are many different 

 types in use which are of thoroughly satisfactory character. The 

 conditions to be met are, firstly, the fixing of the conductors in 



