Thread-tensioning device, particularly for sewing machines

摘要

A thread-tensioning device of a sewing machine comprises thread-squeezing plates between which the thread passes. A shaft applying pressure to the plates is subjected to the action of a transmission lever which is acted upon by a spring-urged ball which is moved by a control button along an arcuate path from adjacent the pivoting axis of the lever to near an end of the lever. The angle of the lever can be set to enable progressive setting of the thread tension for a constant spring pressure, or with variation of the spring pressure.