Patent GB-232896-A (GB)
Title: Lock stitch sewing machine
IPC: D05B57/14
Filed: 1924-02-26
Abstract: 232,896. Fairweather, W., (Singer Manufacturing Co.). Feb. 26, 1924. Sewing-machines; lock-stitching by hooks.- Rotation-restraining means mounted on a movable. bobbin-case support can be manually expanded within a bobbin-case notch to seize the bobbincase for removal from the raceway of a rotary hook. The bobbin-case 43 is mounted within an open raceway 37, Fig. 3, in the hook, and has lateral peripheral flanges 63, Fig. 18, which rest on a disc 64, Figs. 4 and 5, carried by a member 67, which is pivoted at 90, Fig. 4, in a support 88, Fig. 19, on the bed of the machine. An arm 71, pivoted to a feed-lift actuating-lever 25 at 72 and adjustably fixed thereto by screws 74, 75, engages underneath the bobbin-case and lifts it periodically from the disc 64. The disc 64 carries a pin 65 adjustably fixed in a hole in the member 67, Fig. 9, and a lug 76 which loosely engages in a notch 52 in the bobbin-case. A lug 77 on a lever 77, which is pivoted at 77", Fig. 9, to the member 67, also engages in the notch 52 and is normally pressed against the lug 76 by a spring 80 surrounding the pivot 77<11>. A lever 83 pivoted at 84 in a slot in the member 67 carries a pin 82 and has a notch 86 at its lower end to rest on the support 88, Fig. 19, and lock the member 67 in position. A spring 91 is positioned within the slot in the member 67 by a screw 92 which also acts as an adjustable stop for the pin 65. When the lever 83 is manually shifted againt the spring 91 to disengage from the support 88, the pin 82 actuates the lever 77<11> to separate the lugs 76, 77 which grip the bobbin-case and withdraw it from the hook-race when the member 67 is turned out of position. In this way, the under-thread b, Fig. 4, may be cut and the bobbin replaced without dis turbing the needle-thread. The hook, which is rotated three times for each needle-reciprocation, is gapped at 35<1> Fig. 3, to form a beak 36 which has a transversely-convexed outer surface and the heel of which is formed with a loop-arresting notch 42. A bridge-piece 39 over the gap 35<1> is spaced from the hook and has a concave, edge 40, Fig. 5, which deflects the work-limb of the needle-loop over the outer face of the bobbin-case. The bobbin-case has three sectional race-flanges 53<a>, 53<b>, 53<c>, the first of which has the usual loopdetaining hook 54, Fig. 16, while the last prevents the escape of the limb a, Fig. 19, until the hookgap passes the end 55 thereof, Fig. 16. A guardflange 59 protects the beak 36 from re-seizing the needle-loop, which is ejected from the notch 42 by the periphery of the flange. An adjustable tension spring 56 bears on the bobbin-thread between the threading slots 57, 58 from which the thread passes through the notch 52, one wall of which is formed with a ledge 60 to guard the thread against seizure by the beak 36. An undercut loop-detaining horn 61 holds the loop until the limb a has passed through the notch 52, and so prevents twisting of the loop. A raised surface 69, Fig. 18, on the bobbin-case rests against the disc 64 to provide thread-clearance therebetween. Feed by dogs. - A feed-bar 27, Fig. 19, is pivoted t'o an arm 29 of a feed-advancing rookshaft 24, and is connected by a ball-ended link 26 and by a spring 30 to an L-shaped arm 25 on a feed-lift rock-shaft 23.