GB897058A - Start and stop motion mechanism for sewing machines - Google Patents

Abstract

897,058. Sewing machines. SINGER MANUFACTURING CO. Sept. 25, 1958 [Oct. 2, 1957], No. 30656/58. Class 112 [Also in Group XXIV] In a cyclically operated sewing machine wherein a lever 28, controlling the driving clutch 21, 23 and a positive stop 33, is actuated by the machine treadle through a lever 48, link 45, latch lever 43 and adjustable link 40, the arrangement is such that as the lever 28 is turned anti-clockwise about its fixed pivot 29 in moving from a stop position, shown, through an intermediate free position to a clutch-engaged position, the line of action of the link 40 approaches and finally substantially lies on the fixed pivotal axis 44 of the latch lever 43, whilst that of the link 45 becomes perpendicular to its effective latch lever radius 44, 46. Increased mechanical advantage for the final clutch engaging operation thereby obtained reduces the operator's treadle effort. A spring- loaded pawl 55 retains the latch lever 43 in the intermediate free, or final clutch-engaged position and is released through a handle 60 or automatically through a link 61 by a pattern cam. The latch lever 43 is interlocked by projections 70 with a work-clamp opening shaft 66 which is actuated through a lever 69 and a link 68. The clutch is of the kind in which a drive-belt is gripped by its driven pulley which latter comprises a flange 21 fast cn the machine shaft 12 and a freely mounted flange 23 moved axially leftwards, to grip the belt, through a thrust bearing 25 contacted by an arm 27 fast to the lever 28. The lever 28 pivotally carries a stop arm 33 which engages a stop notch 34 in the fast flange 21 to stop the shaft 12 in a predetermined position and is pivoted at its extremity to a plunger 35 resiliently centred by springs 37 to absorb shock. The lever 28 is biased into its stop position by a spring 38.