Seat belt retractor

A seat belt retractor has a retractor frame (10), a belt spool (12) rotatably mounted in the frame, an electric drive motor (14), a reduction belt gear with a toothed belt (28) connecting the electric motor permanently with the belt spool, and a winding spring (30) functionally arranged between the frame and the belt spool, permanently biasing the belt spool with a winding moment. The electric motor is controlled to either counteract or assist the winding spring.