Patent GB-995226-A (GB)
Title: Zigzag mechanism for sewing machines
IPC: D05B19/00
Filed: 1964-04-02
Abstract: 995,226. Sewing machines. SINGER CO. April 2,1964 [April 29, 1963], No. 13572/64. Heading D1G. [Also in Division F2]  A zig-zag sewing machine comprises a plurality of pattern cams rotatable about a common axis, a pivoted cam follower biased towards the cams and slidably movable for selective engagement therewith, and means for rendering the bias inoperative during cam selection. A pitman 8 is pivoted at one end to the swing- ing gate 6 for the needle bar 5. A spring 11, anchored at its respective ends to pitman 8 and a normally fixed lever 12, serves to bias a plate 9, pivoted at 10 to the other end of pitman 8, against a pair of followers 16,17 pivoted on respective shafts 28, 29, to engage the followers with a pack of cams 18 fast with a shaft 19 driven by gearing 20, 21 from the arm shaft 22. A spring 13 acts on one arm of a bell crank lever 14, pivoted at 15, to bias the other arm against plate 9. One arm of a bell crank lever 23, pivoted on shaft 19 is coupled to pitman 8 by a ball and socket joint 26, 27, and the other arm, which passes through a slot 25 in a front panel 4, is formed with a handle which carries a pointer 24 co-operating with a graduated scale on panel 4. A pivoted and axially-slidable shaft 36 is biased forwardly by a spring 44 and carries a crank arm 40 which abuts an arm 41 rigid with follower 16. A blade 31, rigid with arm 40, passes through a slot formed in the bearing hub 32 of follower 16 to enter one of a series of notches 30 formed in shaft 28 at spacings equal to the springs of the cams 18. A crank arm 42 on shaft 36 passes through a slot in panel 4 and carries a handle 43. A sleeve 58, slidable on shaft 36, is biased to a neutral position by a pair of opposed springs 65, 67. A bracket 45, slidable on shaft 36, abuts sleeve 58 and carries a crank arm 48 which abuts an arm 49 rigid with follower 17. A blade 34, rigid with arm 48, passes through a slot in the bearing hub 35 of follower 17 to enter one of a series of arial notches: 33 in shaft 29. A crank arm 46 on bracket 45 passes through a slot in panel 4  and carries a handle 47. Lever 12 is universally pivoted, intermediately, about a horizontal pin 52 and a vertical pin 54. Spring 11 acts on one end of lever 12 to bias the other end upwardly into locking engagement with a groove 56 formed in the undersurface of a fixed plate 55. Pressure on handle 43 serves to shift shaft 36 and sleeve 58 axially, whereby a cam surface 59 on sleeve 58 cooperates with a nose 57 rigid with lever 12 to disengage the latter from groove 56 and thereby release the spring bias on the followers 16,17. The arm 40 also co-operates with arm 41 to raise follower 16 from cams 18, and blade 31 is withdrawn from notches 30 while remaining engaged with hub 32. Rotation of shaft 36, by manipulation of handle 43, then serves to shift hub 32 axially for positioning follower 16 opposite a selected cam. On re-starting the machine, a cam 68 on shaft 22 co-operates with a pin 69 on lever 12 to re-engage the latter with groove 56. Pressure on handle 47 serves to shift bracket 45 and sleeve 58 axially, whereby lever 12 is disengaged from groove 56, arm 48 co-operates with arm 49 to raise follower 17 from cams 18, and blade 34 is withdrawn from notches 33 while remaining engaged with hub 35. Rotation of bracket 45, via handle 47, then serves to position follower 17 opposite a selected cam. Arm 42 passes through an aperture 108 in a plate 100 slidable in a slot 101 formed in a fixed plate 76 behind panel 4. A pointer 72 on plate 100 cooperates with a scale provided on panel 4. Arm 46 passes through an aperture 86 in a plate 79 slid able in a slot 78 in plate 76. On extension 86 of plate 79 is formed with a rack 88 which meshes with a pinion 89 journalled on plate 76. A larger pinion 91, rigid with pinion 89, meshes with a rack 94 formed on a plate 95 slidably mounted, by pins 96 and a slot 97, on extension 86. A printer 75 on plate 95 co-operates with a scale provided on panel 4. The size of the pinions 89, 91 is such that while arm 46 swings through a smaller radius than does arm 42, the graduations of the respective scales are equally spaced apart.