A belt retractor having a belt reel, a safety belt which can be wound thereon to form a wound belt, a pyrotechnic belt tensioner having a drive device which is guided in a tube and can be driven to perform a drive movement, and at least one first further assembly arranged coaxially to the rotational axis of the belt reel and in series with the belt reel, a safety belt which can be wound thereon to form a wound belt, and at least one first assembly, wherein the tube has a straight linear section which extends parallel to the rotational axis of the belt reel and the longitudinal axis of the assembly and is arranged on the side of the belt reel.

A pretensioner apparatus of a seat belt may include a movement tube, a piston movably disposed inside the movement tube, a gas generator fluid-connected to the movement tube and generating a gas upon crash of the vehicle so as to inject the gas into the movement tube to move the piston in a predetermined direction, a linkage unit, a worm connected to the piston through the linkage unit, and a worm wheel engaged with the worm, wherein the worm rotates according to movement of the piston via the linkage unit when the piston moves in the predetermined direction by the gas generated by the gas generator, and wherein the worm wheel fixed to a spool rotates together with the worm to rotate the spool and a seat belt webbing connected to the spool is wound around the spool while the worm rotates according to the movement of the piston.

A seatbelt pretensioner is provided including an inner tube with a gas generator housed therein, an intermediate sleeve extending over the inner tube, and a spool portion housing the sleeve and the tube. The spool portion includes spiraling flutes thereon that correspond to a protruding member in the form of flutes or pegs extending from the intermediate sleeve. In response to the gas generator firing, the sleeve will be driven longitudinally, causing the protruding member to act on the spiraling flutes of the spool, thereby causing the spool to rotate. The intermediate sleeve can include a spiraling slot that receives a peg from the inner tube, so that the intermediate sleeve will rotate to compound the spool rotation.