Needle thread wiper and pull-back mechanism for sewing machines

Claim 1

In a sewing machine having a work support and a sewing head carried above said work support and fitted with an end cover plate, a loop taker arranged beneath said work support, a thread carrying needle supported within said sewing head for endwise reciprocation through the work support in cooperation with the loop taker in the formation of stitches, a needle thread take-up mechanism arranged in the sewing head, and thread trimming mechanism effective to sever the needle thread beneath said work support, mechanism for withdrawing a severed needle thread above the work support comprising a thread wiping arm pivotally mounted within said sewing head end cover plate to swing in an arc traversing the path of the needle thread between said needle and said work support, an actuator for said thread wiping arm, operating mechanism connecting said thread wiping arm to said actuator for imparting movement in a fixed throw to said thread wiping arm, a thread pull-back lever fulcrummed within said end cover plate to swing in an arc traversing the path of the needle thread between said needle thread take-up mechanism and said needle, an operating link for said thread pull-back lever having a connection with said thread wiper operating mechanism and a pivotal connection with said thread pull-back lever, at least one of said connections being adjustable and accessible through an opening in said sewing head end cover so that a change in the stroke of the thread pull-back lever may be effected from externally of the sewing machine.