SWITCHING EQUIPMENT 



559 



on the dial switch is not easily overcome with the solenoid or hand- 

 wheel control. The motor is of the series type with a field wind- 

 ing enabling the dial switch to be operated in either direction 

 by the control switch on the main board. As with the ratchet- 

 driven type, each end of the switch dial is provided with a limit 



FIG. 349. Electrically Operated Motor-driven Rheostat 



switch which is automatically operated by the switch arm to open 

 the motor circuit. 



Voltmeter and Synchronizing Receptacles. These are devices 

 which provide a ready means for connecting a voltmeter to any 

 machine or any phase of the same and thus reduce the number 



