CONSTRUCTION OF SQUIRREL CAGE ARMATURES 101 



method of winding will be clear from Figs. 108 and 110. The bars 

 are cut from hard-drawn copper wire to the required length, and, 

 after being straightened, are driven in the slots from one end with 

 a wrapping of fibre for packing. The end windings are carried 

 out by means of soft copper wire of small diameter, which is twisted 

 round each conductor in succession until nearly the whole of the 

 overhanging portions of the bars has been filled up with these 

 windings. 



The end portions of the windings are then well sweated up 

 with a blow-lamp, or by heating with a gas ring and running in 

 solder, which secures the 

 fine wires to the bars 

 both mechanically and , III | 



electrically. One good 



feature of this winding i-mn 



is that it permits of the -, '/// | 



resistance of the end 

 rings being fairly easily 

 adjusted ; for instance, 

 if after the motor has 

 been installed it is found 

 that a higher starting 

 torque is required, it is 

 a comparatively simple 

 matter to take off a few- 

 turns of the end winding, 

 thus increasing its resist- 



FIG. 110. Drawing showing section of Winding 

 of Rotor in Fig. 109. 



ance, and hence the start- 

 ing torque. 



In the cases of Figs. 106 and 107 it would be necessary, in 

 order to increase the end ring resistance, to mount the complete 

 rotor in a lathe and turn some of the end ring away ; and it 

 may here be pointed out that the end ring should be arranged so 

 that this is possible without interfering with the rotor bars. 

 Thus in Fig. 106 a considerable portion of the section of the end 

 ring projects radially inward, and may be turned smaller at will. 



Before leaving rotors with round conductors, there is another 

 interesting construction depicted in Figs. Ill and 112. This is 

 a construction used by the Alioth Company of Switzerland. A 

 front view of one of the end rings is shown in sketch A in 

 Fig. 112. The rotor bars, after emerging from the slots, are bent 

 down radially. The actual end ring is of the shape indicated in 



