The disclosed seat belt tensioner for a seat belt system may comprise a seat belt spindle, a gearwheel connected to the seat belt spindle, and a latching pawl for locking the seat belt spindle in the tensioned position by engaging in the teeth of the gearwheel. The latching pawl may be configured to be brought into a first pawl position for blocking the gearwheel in the seat belt unrolling direction and into a second pawl position for blocking the gearwheel in the seat belt-tensioning direction of rotation. The latching pawl may also be configured to perform a first pivot-over operation from the first pawl position into the second pawl position and to perform a second pivot-over operation from the second pawl position into the first pawl position when the gearwheel exerts a force on the latching pawl that exceeds a predetermined force required for the respective pivoting-over operation.