Incrementally rotatable thread feeding device for sewing machines

摘要

A thread feeding device for a sewing machine, is simply constructed but can feed a plurality of looper threads individually in amounts necessary for each seam with adjustment of the tensions of the looper threads by one adjustment knob. The thread feeding device includes a shaft fixed on the machine body orthogonally of the feeding direction of a plurality of threads. A rotor is mounted on the shaft as to rotate intermittently in one direction only. A plurality of thread holders are provided on the rotor for holding and letting off the threads individually. In each thread holder the radius from the center of rotation of the rotor to the position where the thread is held is set to a value corresponding to the individual length of feed of the thread.