Abstract: An electric motor includes at least one first brush and at least one second brush, which are arranged in a stationary fashion and arranged to contact a commutator that rotates with a rotor. The commutator includes at least one cylindrical section with a circumferential surface on which a plurality of segments are arranged with insulating sections interposed between them. In order to detect the rotating speed and position of the rotor, the motor includes brushes with asymmetric circumferential widths or angles or a stator with an uneven magnetization. The motor is arranged to detect only one signal when the rotor rotates for an angle between two adjacent segments.

Abstract: The invention relates to a drive unit for automatically actuating a tailgate of a motor vehicle. Connecting the drive unit (4) to the vehicle door (1) or to a transmission device (6) by means of an output shaft (5), said transmission device executing a pivoting movement which corresponds to the pivoting movement of the vehicle door (1), and the drive unit (4) comprising at least one first sensor device (7), which can be connected to an electronic evaluation device (21) and serves to detect the respective angular position of the vehicle door (1). In order to make use of the advantages of an incrementally operating position measurement system of the vehicle door (1), in which, recalibration is necessary not only after the end positions of the vehicle door (1) are reached following a power cut.