Abstract: A looptaker driving arrangement in a zig-zag sewing machine includes: a rotatable drive shaft driving rotation of the looptaker of the sewing machine; a main drive member rotatably supported on the drive shaft; a secondary drive member fixed on the drive shaft for concurrent rotation therewith; a bushing rotatably mounted on the drive shaft with an eccentric outer periphery; and a coupling member rotatably mounted on the periphery of the bushing in eccentric relation to the drive shaft and engaging the main drive member and the secondary drive member. Rotation of the main drive member about the drive shaft axis combined with rotation of the bushing about the drive shaft axis relative to the main drive member angularly accelerates and decelerates the secondary drive member with respect to the main drive member and, in turn, angularly accelerates and decelerates the drive shaft.

Abstract: In a zig-zag sewing machine wherein a sewing needle is shifted laterally with respect to a hook rotated about a fixed axis, the hook is optimally timed with respect to the needle at each shifted stitch position of the needle by accelerating rotation of the hook to advance it into optimal disposition relative to the needle at one stitch position of the needle and decelerating rotation of the hook to retard it into equally optimal disposition relative to the needle at the other stitch position of the needle.