| 摘要 |
<p>A sewing machine that has at least one needle which moves with alternating motion, taking the upper thread through the piece to the sewn, a shuttle to hook an upper thread to form a loop below the piece to be sewn, a bobbin housing in a bobbin-case located internally in the shuttle, the bobbin containing a lower thread which overlaps the upper thread through the loop, two mutually independent levers which act on the upper thread and are mobile with periodic motion between a position where the upper thread is allowed to be fed to the shuttle and a position of complete recovery of the upper thread in which the loop is closed to form a stitch, the upper thread being synchronized with movement of the levers by periodic tension.</p> |
