Abstract: To provide an indexed drive to a device such as a rotary switch having a detent mechanism, a three step-phase stepping motor is wound with only two of the phases (A, B) in its stator slots (S1-S24). Those slots (*) which would carry the third step-phase winding in a conventional machine are left empty. To index the drive from one detent position (I) to the next position (J), first the step-phase (A) and then the step-phase (B) are energized, to take the detent mechanism past its top dead center position (X). The drive then continues to the next position (J) under the detent force and its own inertia, while the step-phase (B) is kept energized to provide electrical retardation to prevent overshoot.