GB1030300A - A needle threading device for sewing machines - Google Patents

Abstract

1,030,300. Sewing machines. G. RALSTON, G. E. A. RALSTON and M. H. RALSTON. Nov. 17, 1964, No. 46704/64. Heading D1G. For effecting automatic threading of a sewing machine needle, a second slidable member is manually depressed to be held by a spring catch in the lowered position, whereby a first slidable member is coupled to the needle bar, and a hook 88 is turned through 180 degrees from the dotted to the full line position. Thread 90 is then laid in hook 88 and in a downwardly-facing hook 154 situated on the opposite side of the needle, said hooks being situated above the needle eye. The machine handwheel is then turned to lower the first slidable member, whereby a spindle 6 rotates to carry a hook 18, formed on a radial arm 15 rigid with spindle 6, through the needle eye, and hooks 88 and 154 descends to place the thread in hook 18. The handwheel is then turned back to its original position, when the first slidable member is raised by spring means to trip the catch holding the second slidable member down, to rotate hook 88 for freeing the thread therefrom, and to rotate spindle 6 for retracting hook 18 to draw the thread through the needle eye. The first slidable member 25 (Fig. 18 not shown), and the second slidable member 28 are mounted one behind the other in the head of the sewing machine. The lower end of spindle 6 is screw-threaded into a fixed tube 3, and the upper part is journalled in a lug 12 rigid with plate 25, and is coupled to lug 12 by nuts 9, 9a. A disc 188, pivoted at 190 to plate 25, carries a pin 200 engaged by a slot in plate 28, whereby, when the latter is depressed, disc 188 is turned to position a lug 204 thereon under a boss 45 (Fig. 8 not shown), on the needle bar 40, and to engage an abutment 199 on disc 188 with a spring catch 201. Hook 88 is carried by a spindle 85 which is screw-threaded into a tube 60 and is spring-biased upwards. Tube 60 is slidably mounted in a fixed tube 63 and is connected by a link 69 (Fig. 10 not shown) to a lever 66 which is pivoted on the machine frame at 77 and carries a pin 80 engaged in a slot in plate 25. The upper end of spindle 85 abuts a plunger 71 slidable in tube 60. Hook 154 is formed at the lower end of a stiff flexible wire 153 which slidably passes through a fixed tube 150 and is connected at its upper end by a member 108 to plunger 71. A lever 125, pivoted at 128 to the machine frame, carries a pin 245 engaged in a slot in plate 28, whereby, when the latter is depressed, the free end of lever 125 depresses plunger 71 to lower hooks 88 and 154 to some extent and to turn hook 88 through 180 degrees, plunger 71 being held in its depressed position by a spring catch 112 carried by tube 60. When the handwheel is then turned to depress plate 25, lever 66 depresses tube 60 to lower hooks 88 and 154 to their final positions. A lever 236, pivoted at 237 to the machine frame, carries a pin 238 engaged in a slot in plate 28, and is formed at its free end with a rounded portion 251 engaged between spaced flanges on a sleeve which screwthreadedly engages a fixed shaft and carries a flap 250, (Fig. 29 not shown), the arrangement is such that when plate 29 is depressed, flap 250 is swung into the path of movement of the thread take-up lever 257 to ensure both that the machine parts are correctly positioned before needlethreading is initiated, and also to limit the amount of possible turning of the handwheel during the needle-threading operation. Hook 18 is normally enclosed in a protective sheath 290 which is pivoted to spindle 6 and engages the needle 43 on turning of spindle 6 to free hook 18 for further independent turning.