Seat-belt retractor

A belt retractor comprising

• a belt shaft that is rotatably mounted in a housing that can be fastened in a vehicle-fixed manner and onto which a safety belt can be wound, and
• an electric motor for driving the belt shaft to a rotational movement, and
• a gear mechanism that transmits the rotational movement from the electric motor to the belt shaft, wherein
• when it is deactivated, the gear mechanism can be driven with a first torque as an assembly for driving the belt shaft, and
• the belt retractor has a first part that is driven to a rotational movement in a direction of rotation opposite to the direction of rotation of the electric motor when a pulling force exerted by the safety belt is exceeded, and that
• a braking device is provided, which brakes the rotational movement of the first part and as a result actuates a blocking device to block a second part of the gear mechanism, wherein
• by blocking the second part, the blocking device activates the gear mechanism to transmit the rotational movement of the electric motor at a reduction ratio to the belt shaft.