CONSTRUCTION OF ARMATURE 



Another mode of supporting the core-plates is shown in Fig. 65. 

 Instead of having clamps on both sides, there is a ring cast on to the 

 yoke, which acts as a clamping-ring. The core-plates are further 

 secured by means of keys screwed to the yoke casting as shown. 



In Fig. 66 is shown a similar construction for a very narrow core, 

 in which case the keys may be dispensed with. 



FIG. 06. Type of Construction for 

 Narrow Armature. 



FIG. 67. Yoke Construction. 



A somewhat different design is illustrated in Fig. 67. Here the 

 yoke-ring itself is divided by a plane normal to the shaft, the two 

 halves of the ring forming clamps for the core-plates. 



Three methods of securing the field-poles to the rim of the field- 

 wheel are shown in Figs. 68, 69, and 70. In Fig. 68, each pole is 

 secured by two bolts passing through the rim, while in Fig. 69 



FIG. 68. Field-polo Construction. 



additional safety is obtained by providing the rim with a clamping 

 projection on one side and the field-pole with a similar projection on 

 the other. For very high peripheral velocities, the field-poles may 

 be dove-tailed into the rim as in Fig. 70, and secured by means of 

 wedges. 



Owing to the high peripheral velocities (7000 feet per min.) 

 common in alternators, ordinary wire winding is inadmissible for the 



