Patent attributes
A threading device for a sewing machine includes a needle bar provided with a guide member having a stopper portion, a threading shaft having a threading member, operation means having a guide groove formed in a spiral shape with respect to a rotating axis of the threading shaft, and a pin, which is fixed to the threading shaft, having both ends protruded outward in a radial direction with respect to the threading shaft. One end of the pin penetrates the guide groove while the other end of the pin engages with the stopper portion. The threading device further includes erroneous rotation preventing means which prevents the threading shaft from rotating in when the threading shaft moves downward, and permits the threading shaft to rotate when the second end of the pin engages with the stopper portion.
