Thread tension device for overedge sewing machines

A thread tension device for overedge sewing machines, comprising:

• a shaft having a longitudinal dimension axially thereof;
• support means for supporting said shaft with its axis held in a fixed position;
• a plurality of tension disk assemblies mounted on said shaft so that they are spaced apart from each other in axially distributed relationship, each of said tension disk assemblies having corresponding first and second tension disks forming a pair to hold therebetween a thread to be tensioned;
• each said first tension disk being axially movable in either direction with respect to said shaft;
• each said second tension disk being inhibited from moving axially in at least one direction away from a corresponding one of said first tension disks;
• and
• tension adjusting spring means for each of said tension disk assemblies, having an active portion for exerting a resilient force on the corresponding first tension disk, said active portion serving to urge said corresponding first tension disk against the corresponding second tension disk as it is displaced in the direction of action of said resilient force, wherein said shaft is rotatable around its axis, and further including thread tension releasing means for displacing said active portion of said tension adjusting spring means in a direction opposite to the direction of action of said active portion in response to the rotation of said shaft in one direction, thereby inhibiting said first tension disk from being urged against said second tension disk, and manual operating means for rotatively operating said shaft in at least said one direction.