68 



ARMATURE CONSTRUCTION 



laminations are assembled in one half of the frame, and the other 



half laid on and 

 the two bolted to- 

 gether. 



In stationary 

 armatures of large 

 diameter it is neces- 

 sary for the section 

 of the frame to be 

 of considerable 

 depth, to render it 

 suthciently rigid to 

 stand its own 

 weight and that of 

 the armature, with- 

 out deflecting. 1 In 

 cases of very large 

 frames (up to 30 

 feet diameter) they 

 are sometimes 

 stiffened up by a 

 system of tie-rods 

 arranged round the 

 outside of the 

 frame. The results 

 obtained by this 

 latter method have 

 not been altogether 

 satisfactory. 



Fig. 72 shows 

 a typical frame for 

 smaller size arma- 

 tures. 



1 A useful method 

 of determining the 

 dimensions of box 

 type frames is given 

 by R. Livingstone in 

 the Electrician, vol. 1 v i i . 

 pp. 569-571, 1906: 

 "Some Notes on the 

 Mechanical Design of 

 Fro. 65.- -Methods of Keying Armature Laminations. Electrical Generators." 



