Patent GB-219587-A (GB)
Title: Improvements in sewing machines
IPC: D05B85/06
Filed: 1924-01-08
Abstract: 219,587. Avis, S. W. Jan. 8, 1924. Loop-stitching; needles, driving.-In a sewing- machine for overseaming a needle oscillating thread loopers and reciprocating feed-dogs are all operated by cams mounted on a single rotary shaft parallel to the direction of feed and arranged below the work-plate. The shaft 1, mounted on bearings 3, 4, 5, carries a cam 9 which oscillates a lever 12 secured to one end of a long tapering arbor on the further end of which is mounted a needle carrier 15 bearing a curved needle 16. The loopers 30, 31 operate transversely to the line of feed one above and one below the surface of the work-plate 18, and are actuated by a cam-groove 19 in the cam 9 which engages rollers on rockerarms 22, 23 mounted on the tapering shafts 24, 25 which carry the loopers. The loopers are secured in radial slots in these shafts by axial clampscrews 33. Feed by dogs; duplex feed.-A front feed-dog 37 and rear feed-dog 38 are given lifting and feed movements from a single cam 36. The feed-dog 38 is secured to a carrier 39 having a cylindrical under-surface fitting in a fixed block 40. A pair of lugs 41, Fig. 14, project, downwardly from the carrier and are engaged by a tooth 42 projecting from a forked lever 43 embracing the cam 36. A rocking movement is thus given to the carrier and a rising and falling movement to the dog. The dog 37 is attached to a carner 46 having an angular lower surface fitting in a corresponding recess in the carrier 39, and is held in position by a fixed plate 47 having a cylindrical surface resting on the upper surface of the carrier 46. The feed dogs are oscillated together by this arrangement. Separate variable feed-motions of the dogs are effected by mechanism comprising a yoke 48, Fig. 11, embracing the cam 36 and guided by a roller 49. Rollers 51 carried on each side of the yoke engages radial slots 52 in adjustable bell-crank plates 53 mounted on tapering arbors 54 seated eccentrically in cylinders 55 rotatable within openings in the casing. Curved slots 62 in the plates 53 receive rollers 63 mounted on bell-crank levers 64 which have concentric arbors 65. 66 and carry rollers 67, 69 engaging slots 68, 70 in the dog-carriers 39, 46 respectively. By rotating the cylinders 55 the relative positions of the rollers 51 and the pivots of the plates 53 are varied and the throw of the feed-dogs independently adjusted. Trimming.-A fixed blade 73 and movable blade 74 are supported in a housing 75 which may be adjusted to vary the width of trimming or swing away from the stitch-forming implements. The housing is attached to a sleeve supported in a yoke-shaped frame mounted on an arbor 78. A projection 93 on the housing is pivoted to a link 90 pivoted on the frame and provided with a finger-piece 91 by which the adjustment is effected. The movable blade is secured to an arm 81 projecting from a shaft 82 from which also projects an arm 83 connected by a link 84 to a bell-crank lever 85 mounted on the arbor 78 and rocked by an eccentric driven by the shaft 1. Presser-bars.-A presser-foot 95 is pivotally mounted on a bar 96 depending from an arm 97 pivoted to the wall of a cover 98 and pressed by a spring 99. The bar 96 is pivoted to the arm 97 but is normally locked thereto by a dog 102 held in a notch in the arm 96 by a spring 105. On withdrawing the dog from the notch the arm 96 may be turned up out of the way. Specifications 219,588 and 219,589 are referred to.