Abstract: In an electromotor having a stator and a rotor, a collector is located on the rotor and carbon brushes are movably supported in carbon supports relative to the outer circumferential periphery of the collector. Segment-shaped shells are located on the upstream sides of the carbon brushes and cover an angular part of the outer circumferential periphery of the collector. Downstream of the carbon brushes the outer circumferential periphery of the collector is uncovered. Accordingly, the collector can be cooled while protecting the collector and carbon brushes from contamination.