MIXED-ACTION MOTORS 285 



short-circuit the winding as in a repulsion motor. A power- 

 ful starting torque is thereby obtained. When the speed exceeds a 

 mi. tin limit, a centrifugal governor mounted on the motor shaft 

 ciuses a collar to slide against the brush rocker ring, lifting the 

 bruslii-s dear of the commutator;* while at the same time a short- 

 circuiting ring is forced into contact with the inner surfaces of the 

 commutator segments, completely short-circuiting the individual 

 armature coils, and thereby converting the motor into a single-phase, 

 constant-speed induction motor. 



The Schiller motor (Fig. 177) is provided with an ordinary star- 

 connected stator winding, of which only two phases (in series with 

 each other) are in use at a time. By interchanging one of the active 



FIG. 177. Diagram of Schtiler Motor. FIG. 178. Diagram of Fynn Motor. 



phases and the idle phase (by means of the switch shown in the 

 diagram) the motor may be reversed. The rotor has a continuous- 

 current winding, fitted with a commutator on one side and three slip- 

 rings on the other. At starting, the slip-ring circuits are open, and 

 the motor starts as a simple repulsion motor. By closing the slip- 

 ring circuits through starting resistances such as are ordinarily used 

 in connection with three-phase induction motors, and gradually short- 

 circuiting the resistances, the motor is transformed from the repulsion 

 to the induction type. 



Another interesting and successful type of repulsion-induction 



* The commntator bearing surface IB vertical, forming an annular ring; a displace- 

 ment of the brush rocker parallel to the shaft will, therefore, move the brushes away 

 from the commutator. 



