Patent GB-1164899-A (GB)
Title: Cam Selection Mechanism for Zigzag Sewing Machines
IPC: D05B19/00
Filed: 1967-05-02
Abstract: 1,164,899. Sewing machines. SINGER CO. 2 May, 1967 [4 May, 1966], No. 20150/67. Heading D1G. A zig zag sewing machine comprises a rotary shaft imparting reciprocation to the needle, a plurality of co-axial pattern cams, cam follower means shiftable relatively to said cams into selective engagement therewith, spring means biasing a needle-displacing linkage into operative engagement with the cam follower means, a displaceably-mounted anchor member for the spring means, a shiftable latch block for constraining the anchor member in such position that the spring means is effective, operator-influenced means effective in any position of said shaft for shifting the latch block to release the anchor member from the position of constraint, and cam means driven by said shaft for shifting the anchor member into the position of constraint. A pack of cams 18, journalled on a post 19 and driven by gearing 20, 21 from the arm shaft 22, co-operates with cam followers 16, 17 pivoted on respective posts 28, 29. The cam followers are engaged by a plate 9 pivoted at 10 to one end of a link 8 pivoted at its other end to the needle bar gate 6. A spring 11, extended between gate 6 and a normally fixed lever 12, biases plate 9 against the cam followers. A spring 13, extended between lever 12 and one arm of a lever 14 pivoted at 15, biases the other arm against plate 9. A rotatable and axially slidable shaft 36 carries a handle 42 and a crank arm 40 biased by a spring 44 to engage a blade 31, rigid with arm 40, with a slot in the hub 32 of follower 16 and with one of a series of slots 30 in post 28. Inward pressure on handle 42 thereby serves to disengage blade 31 from slot 30 and to engage arm 40 with an extension 41 of follower 16 to raise the latter from the cams. Handle 42 may then be turned to align blade 31 with a slot 30 corresponding to a selected cam. A bracket 45, rotatable and slidable on shaft 36, carries a handle 46 and a crank arm 48, and is biased by a spring (50) to engage a blade 34, rigid with arm 48, with a slot in the hub 35 of follower 17 and with one of a series of slots 33 in post 29. Handle 46 may be manipulated both to disengage blade 34 from slot 33, when arm 48 engages an extension 49 of follower 17 to raise the latter from the cams, and also to re-align blade 34 with a slot 33 corresponding to a selected cam. One arm of a lever 23, pivoted on a post 19, has a ball and socket connection 26 to link 8, and the other arm carries a handle 24 for swinging link 8 to place pivot 10 in adjusted position either between the followers 16, 17 or in alignment with either one of the followers. Lever 12 is universally pivoted to the undersurface of a fixed plate 55, and the end to which spring 11 is anchored is so weighted that the other end 62 is biased against the undersurface of a latch block 60 pivoted at 61 to plate 55, and normally engages an abutment surface 66 on a lug 64 projecting downwardly from plate 60. A pin 68 projecting upwardly from plate 60 is biased by a spring 69 against one arm 72 of a two-armed lever to engage the other arm 73 with an inclined surface 79 on a lug 78 projecting laterally from a sleeve 77 which is slidably but non- rotatably mounted on shaft 36, and is biased by a spring 80 against bracket 45. Inward pressure on either of handles 42 or 46 thereby swings plate 60, via pin 68, to disengage end 62 from surface 66 for unstressing springs 11 and 13, end 62 then being guided by a cam surface 65 on lug 64 to engage the undersurface of the latter. A pin 85, extending downwardly from lever 12, is thereby moved adjacent shaft 22, whereby, when the latter next operates, a cam (86) thereon cooperates with pin 85 to shift end 62 into engagement with surface 66. Bracket 45, in a position of extreme angular adjustment corresponding to straight stitching, engages one arm 93 of a U-opening to engage the other arm 94 with plate 9 for biasing the latter against the followers 16, 17.