A belt retractor having a belt shaft which is mounted rotatably on a frame fastenably fixed to a vehicle and on which belt shaft a seat belt can be wound, and having an electric motor for driving the belt shaft to perform a rotational movement, and having a shiftable planetary transmission which transmits the rotational movement from the electric motor to the belt shaft, having a planet carrier, and having a plurality of externally toothed planet gears which are mounted rotatably on the planet carrier and which, in order to produce a driving rotational connection, engage by means of their toothings in a toothing of a drive gear, which is driven by the electric motor, and, for the production of a driving rotational connection, said planet gears engage in a toothing of an output gear which is in driving rotational connection with the belt shaft.

In a system and a method for adjusting seat belt pressure, in which while a passenger in a vehicle is wearing a seat belt, a webbing shape and pressure applied to a passenger's body by webbing can be detected, and webbing pressure adjustment drive devices can be operated based on the detected data so that local pressure applied to the passenger's body by webbing can be reduced, thereby relieving seat belt pressure. The system can include body pressure sensors, a camera, a controller, and various webbing pressure adjustment drive devices.