GB502792A - Improvements in or relating to sewing machines - Google Patents

Abstract

502,792. Sewing - machines. UNION SPECIAL MACHINE CO. July 24; 1937, No. 17676. Convention date, July 25, 1936. [Class 112] In a lock-stitch sewing-machine of the rotary-hook type, a needle-thread looptaker 35, which may be of aluminium, or a light alloy, is lightened by cutting parts away and frictional forces are decreased by having means to secure slight axial pressure on the bobbin holder 47. The latter has a circumferential rib 49 extending around its body 50, the rib being interrupted at 51 to clear the needle thread loop L, Fig. 5, and the gap between shoulders 52, 53. 52 is the needle loop detaining horn, and the thread loop is released over the tapered shoulder 53. The rib is cut away at 54, Fig. 6. Fig. 4 shows the rib 49 bearing upon a circumferential surface 55 of the hook 36 formed by an annular shoulder 56 within the hook, and a flanged segment 57, secured by screws 58, which provides the loopshedding tail 45. The groove 55 is considerably wider than the rib 49. A vertical notch 61 in the flange 59 loosely engages the lateral projection 62 of a stationary. finger 63. The portion of the body 50 forward of the rib 49 is in the form of a circumferential segment corresponding with the face flange 59, but open except for connecting webs 70, 71. The rounded rear portion of the body 50 is reduced to the form of a circumferential segment, which provides a surface for directing the needle thread over the back of the bobbin within the holder 47. A diametral rib 6S connects the ends 73. The bobbin case 74, Fig. 5, is cuplike in shape and constructed from a light metal or alloy. It has a notch 75 which engages a projection 76 within the holder 47, to prevent its rotation as the bobbin thread is withdrawn. A tubular axial stud 77 on the case 74 fits over an axial stud 69 of the case holder 47. Openings 81, 82, are provided for lightness. A plate 87 keeps the case 74 and spool 78 in place. An arm 89, Fig. 1, hinged at 90, is kept in the closed position as shown by a spring 93 bearing on a flat 95, or held in the open position (shown dotted) by another flat 94. The upper portion of the arm 89 is roughened R for convenience of grasping between thumb and forefinger. The keeper plate 87 is axially adjustable to compensate for wear in the rib 49 and to adjust clearances between spot projections 99, 100, on the face of 87, and the outer face of the bobbin case 74 and face flange 59 respectively, just widely enough to allow free passage of needle thread N. The spool 78 is made of aluminium or a light alloy. U.S.A. Specification 2,077,151 is referred to.