Sewing machine - has gripper and spool thread brought from external reel through hollow drive-shaft

摘要

The shuttle mechanism on sewing machine has driveshaft to revolve the gripper, with thread fed continuously from spool. The driveshaft is arranged to have central bore, so that the thread may be fed through from an external reel, without accumulation on an encapsulated spool. Pref. the shuttle unit beneath the needle plate, has hollow passage along the interior of the drive gear and to the fixed spool case, running with projection from the case in a groove. The spool case contains an open end spool held by a plate and screw. The case is prevented from rotation by the finger fixed to the machine base. The thread from the interior is guided and tensioned from the spool in the usual manner. There is also tension for the thread as it is drawn from the external reel. The thread passes along the bore and into the spool case through passage in the central shaft of the case, and is unhindered by the spool at the exit. The needle brings down the top thread which is trapped by the gripper as it revolves, forming loop which passes across the face of the spool and enclosing the thread. The loop is taken back by the take-up lever, forming a stitch which locks the two threads. ADVANTAGE - The repetitive process of winding spool and fixing it into the shuttle encapsulation is eliminated. The top thread reel may be the same size as the bottom thread reel, and sewing may continue uninterrupted for this period.