Importance

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Abstract

A safety belt tensioner is provided for pulling a buckle part to tighten a safety belt system about an occupant. The tensioner includes a flexible member or cable having a first loop connected to the buckle part which pulls the buckle part when it is shortened, as by actuation of a power operated device such as a piston-cylinder device. To shorten the piston stroke while achieving the necessary displacement of the buckle part, the flexible member is provided with a second loop connected to the piston about a turning member thereof with one end of an anchored half of the second loop secured to a stationary part of the pretensioner, and the other loop half extending from the cylinder and connected to the portion of the flexible cable member for the buckle part. This provides about a 1:1 ratio between the length of piston travel and downward travel of the buckle part to minimize the piston travel to allow the length of the cylinder to be shorter for providing a more compact pretensioner. In a preferred form, the piston has a rotatable bearing member about which the second loop extends which reduces friction on the cable when the piston is fired.

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First Claim