GB633269A - Sewing machine work-clamping mechanism - Google Patents

Abstract

633,269. Buttonhole sewing-machines. FAIRWEATHER, W. C. (Singer Manufacturing Co.). Feb. 11, 1948, No. 3997. [Class 112] Work-clamps. A pivoted workclamp arm is actuated by mechanism including a pair of toggle members, the arm preferably being yieldingly connected to a lever fulcrummed on the pivot of the arm ; the clamp may be opened and closed by hand or automatically. In the embodiment shown, in a buttonhole sewing-machine, the clamp is formed in two halves, as usual, and each upper half 34 is carried by an arm 32 pivoted at 31 and connected by a rod 38 and spring 40 to a bent lever 36 also pivoted at 31 ; the lever 36 is connected by a link 44 to an arm on a rock-shaft 47, the arm and link forming a toggle connection which locks the lever 36 down when the clamp is closed, the members 34 then being pressed down by the springs 40. The shafts 47 for the two halves of the clamp are connected by a coupling allowing relative longitudinal movement between the shafts ; one of the shafts has fixed to it a lever having a handle 53 and an arm 54 for engagement' by a clamp-closing lever 55 actuated by a cam 57 on a shaft which makes one revolution before the start of stitching, while the other shaft has an arm 59 for engagement by a spring returned push-rod 61 which is actuated through an arm 63, by a cam on a shaft making one revolution after stitching, to break the toggle and allow the clamp to be opened by a spring bearing on the lever 36. Specifications 9458/12 and 146,587, [both in Class 112], are referred to.