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MOTORS AND MOTOR-DRIVING

magnet were a permanent hard steel magnet of the same shape.

The two other types of motor are the shunt-wound motor, fig. 5, and the series-wound motor, fig. 6. In the shunt-wound motor the current, which is led by two conductors from opposite ends of the battery of accumulators to the brushes which supply the current to the commutator, and so to the

Fig. 5


armature, branches off from those brushes and goes round the coils wound on the field magnet. In the series motor the current traverses the field winding either before or after passing through the armature. There is a fourth variety of motor, known as the compound, in which the field magnet has both series and shunt windings. This type of motor is used in the Krièger cars.

The characteristics of series and shunt motors are different. The shunt motor tends to run at constant speed, no matter