Pyrotechnical drive

The linear pyrotechnic drive (20) has a cylinder (22) containing a piston (24) and a sprocket (30). The piston has teeth (30) which can engage with the sprocket to rotate it as the piston is displaced, There is at least one yielding element (34) to prevent blocking as the teeth run in. The belt rolling-up device (10) has a belt spool (14) and a belt tightener equipped with the described linear drive.