In a starter motor, many armature segments must be used. As one segment rotates past the stationary magnetic field pole, another segment immediately takes its place. The turning motion is made uniform and the torque needed to turn the flywheel is constant rather than fluctuating, as it would be if only a few armature coils were used. Starter motors are usually series-wound motors. Current is flowed through the motor circuit in a single series path. It is first routed to the field coils and from there routed through the armature. This is one factor that enables cranking motors to produce maximum torque at zero rpm. All serieswound motors produce maximum torque at low rpm close to stall.
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