Trw Vehicle Safety Systems Inc.

Charles W Sorenson

Robert P Ellis

Keith R Ball

Carl M Petersen, Iii

Timothy J Cahill

A pretensioner (40) is connected with a seat belt buckle (32) and is operable to move the buckle through a pretensioning stroke to remove slack from a seat belt. Movement of an actuator member (36) from an unactuated position to an actuated position under the influence of its own inertia at the end of a pretensioning stroke is resisted by a pair of counterbalance assemblies (162, 164) disposed in the buckle (32). The counterbalance assemblies (162, 164) include masses (168, 176) having inertia which results in the application of force against counterbalance cams (212, 232) connected with the actuator member (36). This force resists movement of the actuator member (36) to an actuated position at the end of the pretensioning stroke. Upon the application of manual force against an outer end portion of the actuator member (36) to release the buckle, the masses (168, 176) are pivoted by the counterbalance cams (232, 212). Cam followers (196) connected with the masses then slide along longitudinally extending side surfaces (216, 240) of the counterbalance cams (212, 232). The counterbalance masses (168, 176) are mounted between elongated sections (132, 134, 148 and 150) of the actuator member (36).

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Utica, MI, United States of America

Charles W Sorenson