Position adjusting device for a shoulder belt of a seat assembly

Claim 1

A position adjusting device for a shoulder belt in a seat belt assembly, comprising: a guide rail adapted to be attached to a vehicle and having upper and lower portions; an anchor support member having a surface portion slidably attached to and engaged with the guide rail adapted to support a belt anchor; a screw shaft disposed parallel to the guide rail and having a thread surface and upper and lower ends rotatably attached to the upper and lower portions of the guide rail, said upper end of the screw shaft being supported by and suspended from the upper portion of the guide rail; a movable member screwed to the screw shaft, said movable member being moved along the guide rail when the screw shaft is rotated, said movable member having a thread surface and means for loosely supporting the anchor support member in a lateral direction perpendicular to the guide rail so that lateral force applied to the anchor support member perpendicular to the guide rail is substantially directly supported by the guide rail without affecting to the screw shaft; and a surface layer formed of solid lubricant, said surface layer being formed on at least one of the thread surfaces of the screw shaft and the movable member.