A commutated DC motor has a set of <answer>rotating</answer> windings wound on an armature mounted on a <answer>rotating</answer> shaft. The shaft also carries the commutator, a long-lasting rotary electrical switch that periodically reverses the flow of current in the rotor windings as the shaft rotates. Thus, every brushed DC motor has AC flowing through its <answer>rotating</answer> windings. Current flows through one or more pairs of brushes that bear on the commutator; the brushes connect an external source of electric power to the <answer>rotating</answer> armature.
What is the main feature of the shaft in a commutated DC motor?
rotating