Abstract: The invention relates to a safety belt arrangement in vehicles having a belt tensioner comprising: a holder which is to be secured to the vehicle chassis, with a belt winding reel with a safety belt wound thereon being rotatably mounted on the holder; a belt retraction spring arrangement by means of which the safety belt is continuously lightly pretensioned in the draw-in direction so that it only loosely lies against the vehicle occupant secured by it; and an auxiliary drive which is separated drivewise by a clutch from the belt winding reel but is activated abruptly with an accident-dependent acceleration and is rotationally fixedly coupled to the belt winding reel via the then engaged clutch.

Abstract: A belt tensioner for safety belt arrangements in motor vehicles has a holder (11) on which are provided a belt winding reel (12) with a safety belt (13) coiled thereon, a blocking arrangement and an additional drive (15) connected via clutch (20) to the belt winding reel (12). The additional drive (15) contains a pressure source (16) which abruptly builds up a high pressure in a pressure chamber on being triggered and also contains a torque generating device (18) acted on by the pressure in the pressure chamber (17) and a drive shaft (19) connected to the latter. The drive shaft (19) is rotationally fixedly connectable to the belt winding reel (12) via the clutch (20).