| 摘要 |
A fabric-transport device for a sewing machine above the stitch plate converts the rotary motion of the main upper drive shaft into reciprocating vertical motion of a pressure (hold-down) foot and a feed foot. The rotary motion is converted by a crank disc connected to a bell crank via an input crank. The bell crank swings a composite connecting rod, comprising a sliding link which interconnects the bell crank with a ternary link carrying the feet and comprising a guide bar for guiding the sliding link. The ternary link is spring-loaded against the stitch plate by a swingable arm and alternatingly lifts the pressure foot and the feed foot. The system provides for fast reduction of the velocity, towards zero velocity, of the feet as they depress to engage with the material to be sewn. |
