Thread tension device for overedge sewing machines

Abstract

A plurality of tension disk assemblies in an overedge sewing machine are disposed on a shaft supported for rotation around its axis and are spaced apart from each other in an axially distributed relationship. Each tension disk assembly comprises first and second tension disks forming a pair for holding therebetween a thread to be tensioned. The first tension disk is movable in opposite directions axially of the shaft, and the second disk is substantially immovable in the direction of the axis of the shaft. The resilient force of a spring acts on each first tension disk, whereby the latter is pressed against the second tension disk associated therewith. When the shaft is turned, as by a manual operating lever, this rotary motion is converted into a linear motion through a cam device. This linear motion removes the resilient force of the spring from the first tension disk. Thus, a thread tension released state is established simultaneously in the plurality of tension disk assemblies.