Abstract: A seat belt retractor which achieves stable performance of a pretensioner. The seat belt retractor includes a spool for winding up a belt thereon. The spool has a shaft portion, a spool gear, and a spring-biased shaft projection which are disposed to project from a face of the spool. A spool bearing (or ring-like collar) is fitted around the shaft portion of the spool. The spool bearing is made of a material having high hardness and high rigidity such as SUS or SC. By this spool bearing, the spool is prevented from being directly subjected to load, like a bearing.

Abstract: A seat belt retractor with a ball type pretensioner including a pipe in which the balls are retained. A front end portion of the pipe is securely retained so that reliable operation of the pretensioner is provided. The pipe does includes a cut-out that does not extend to the front-most end of a pipe. A guide block is fitted in the front-most end of the pipe. The pipe and the guide block are fixed to the plate together by a fastener. The portion where the guide block is fitted to the pipe can provide high rigidity and is thus hardly deformed in every directions. The fastener may be hardened or the material for the fastener may be selected to obtain sufficient strength.

Abstract: To provide a pre-tensioner which can effectively use ignition pressure of a gas generator and can be constructed in a compact form as a whole and have lighter weight, a pre-tensioner 10 is mounted outside of a side wall 50 of the frame 2 by a base 41. A hexagonal head portion 4d of a reel 4 penetrates a base 41. Fixed to the outer periphery of the hexagonal head portion 4d is a pinion 23. The pinion 23 is provided with external teeth 24 uniformly formed around the periphery thereof. A ring gear 30 is disposed to surround the pinion 23. The ring gear 30 has internal teeth 31 engageable with the external teeth 24 of the pinion 23. The ring gear 30 has levers 32, 33 projecting outwardly, which are formed on the outer periphery of the ring gear 30 at predetermined interval. The lever 32 of the ring gear 30 is substantially in contact with the head ball 20-15 within the pipe 21.

Abstract: A seat belt retractor of the invention is basically formed of a first reel, a second reel, a rope extending between the first reel and the second reel, and a spiral spring situated in the second reel as an urging force providing device. The first reel is connected coaxially to a rotational axis of a reel shaft for winding a webbing, and has a drum shape on which the rope fixed at one end to the first reel is wound. The second reel has a rotational shaft disposed parallel to and laterally spaced away from the first reel. The second reel includes a small diameter reel portion, a large diameter reel portion, and a transition portion connecting the small diameter reel portion and the large diameter reel portion. The rope attached to the first reel extends to the small diameter reel portion and the transition portion, and is wound around a groove of the large diameter reel portion.