sewing machine with a armwelle and at least another wave angetriebenem upper and lower band

摘要

The deflecting rollers (31,32) are mounted on pivoting levers (33,34) to carry the upper belt of the sewing machine fabric advance system, where there is an upper and lower fabric carrier mechanism. The axis (35) of the deflecting roller (31), at the drive roller (36), is at one end of a triangle formed by it with the axis (37) of the drive roller (36) and the pivot (38) of its lever (33), forming an obtuse angle for the triangle. An extension of one side of the triangle and the auxiliary line define a zone to contain a further deflecting roller. The triangle side extension and the auxiliary line meet the further deflecting roller at a tangent at their extreme ends. The layout allows the use of a thin band to advance the fabric, with low band tension, so that it will stretch if a braking action is applied by any blockage during sewing.