GB1392873A - Control emchanism in a sewing machine - Google Patents

Abstract

1392873 Sewing machines UNION SPECIAL MACHINE CO 28 April 1972 [30 April 1971] 19759/72 Heading DIG In a blind stitch sewing machine, depressing a control arm 57 raises the node former 21 and work clamp 22 into engagement with the presser foot 17, and depressing the arm further disengages a stop 68 from a pulley 71, allowing the machine to start sewing a group of stitches, the number of stitches being determined by a cam 73. The node former and work clamp are supported by a node former frame 26 which is raised by a link 34 joined to a crank 35 on a shaft 37. This shaft may be partially rotated by a parallel shaft 41 through levers 43, 44, 45. There are two bell crank levers, one (42) has a cam follower 53 riding along a cam aperture 51 in the other. On first depressing the control lever 57 another arm 48 of the bell crank 54 rotates clockwise, moving the cam follower to the entrance of the slot 52, and also bringing a stud 65 on another arm of the bell crank, against a lever 67. Depressing the control lever 57 further causes the cam follower to move into the slot 52, but not to rotate further, and the stud 65 pushes the lever 67 and stop 68 sideways to release the pulley 71. A clutch is then engaged to start the machine. A spring 60 retains the levers in this position when the chain 58, which may be attached to a treadle, is released. A rotating cam 73 has three sets of notches, and a lever 75 is adjusted to select one set. As the cam rotates the follower 83 drops into the next notch and so rotates the shaft 56 to initiate the stopping of the sewing cycle. The three sets of notches correspond to cycles of 6, 8, or 12 stitches.