THE SINGLE-PHASE SERIES MOTOR. 



319 



copper ring K into contact with the inner ends of the commu- 

 tator segments and lifting the brushes off the commutator. The 

 machine then operates as a single-phase induction motor. The 



Fig. 273. 



LJLJ 



ABEDEFCHIJKLM 



tots 



Fig. 274. 



lifting of the brushes off the commutator is not necessary but de- 

 sirable in order to reduce friction and wear. 



