Abstract: An arc length in contact with a commutator of two brushes in a rotational direction of a motor is defined as not more than 5% of an outer rim length or circumference of the commutator, i.e., not more than ?A/2O, where A is an outside diameter of the commutator. A number of shorted segments of the commutator, which short is caused by the brush, can be minimized so that reduction in output of the motor can be prevented. As a result, the motor employed in a car product or an electric tool can be downsized and made lighter.

Abstract: The present invention provides for its object a compact electric motor effective to provide a high reliability against the leakage of grease from a bearing on one side adjacent the output shaft or the ingress of oil from a counterpart machine. The compact electric motor 1 has a wall 14 having a predetermined gap around an output shaft 3 between a commutator 7 and a bearing 6, wherefore in the event of leakage of grease from the bearing 6 on an output side or ingress of oil from the counterpart machine, it is possible to prevent deposition on the commutator 3 and the brush 5 and, hence, to avoid an abnormal wear of the brush 5 and reduction in performance of the compact electric motor 1.

Abstract: The present invention provides for its object a compact electric motor effective to provide a high reliability against the leakage of grease from a bearing on one side adjacent the output shaft or the ingress of oil from a counterpart machine.

Abstract: An arc length—contacting with a commutator—of two brushes in a rotational direction of a motor is defined as not more than 5% of an outer rim length of the commutator, i.e., not more than &pgr;×/20, where A is an outside diameter of the commutator. A number of shorted segments of the commutator—the short is caused by the brush—is minimized, so that reduction in output of the motor can be prevented. As a result, the motor employed in a car product or an electric tool can be downsized and light-weighted.

Abstract: A DC motor has a projection which projects from the bottom surface of the brush-holder plate. The projection extends to outside in the axial direction of the motor. A terminal conductor is inserted into a perforated hole formed in the projection. One end of the terminal conductor is exposed to the outside of the motor from the tip of the projection, while another end of the terminal conductor is connected electrically to the brush. The projection functions as the built in type electrical connector to the motor, which when coupled to a power supply, powers the DC motor.