COMMUTATOR CONSTRUCTION 



125 



In general, the breadth of the segment at the periphery of the 

 commutator should not be, except in the case of very small motors, 

 less than about 4 mm., but there is no reason why smaller thick- 

 nesses cannot be employed in certain cases. The factors which 

 limit the thickness of the bar are the method of manufacturing 

 the bars and the mode of attaching the lug, or the ends of the 

 armature winding. In fact, a thickness down to less than 3 mm. 

 may be quite practical, as is instanced by the following figures 

 quoted by E. Livingstone : l 



014 in. (3'6 mm.) thickness in a commutator 30 in. (760 mm.) 

 diam. x 9 in. (228 mm.) long. 



FIG. 145. 



FIG. 146. FIG. 147. 



Methods of attaching Commutator Lugs and connecting to Armature Conductors. 



0-125 in. (3'2 mm.) thickness in a commutator 19 in. (482 mm.) 

 diam. x 10^ in. (260 mm.) long. 



O'lOo in. (272 mm.) thickness in a commutator 15 in. (380 

 mm.) diam. x 5J in. (140 mrn.) long. 



0'098 in. (2-5 mm.) thickness in a commutator 8 in. (203 mm.) 

 diam. x 3 in. (76 mm.) long. 



As further examples, the following are four cases from the 

 writers' designs : 



3*1 mm. thickness of segment 185 mm. diam., 30 mm. long. 

 2-2 ,, ,, 254 65 



3'0 ,, ,, ,, 200 ,, 50 



3-0 280 70 



1 Mechanical Design of Commutators for Direct Current Generators, 

 Electrician, vol. Ivii. pp. 171-172, May 18, 1906. 



