Patent GB-699996-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B81/00
Filed: 1951-12-28
Abstract: 699,996. Sewing-machines. VOLKMANN,G. Dec. 28, 1951 [Jan. 4, 1951], No. 30278/51. Class 112. A chain-stitch sewing-machine, particularly for sewing a lining in a fur garment, comprises a structure mounted on rollers to be shifted over the work by means of a motor carried by the structure, which also carries a claw engaging the work to form a wave therein for engagement by the needle. Portable machines; blind-stitching and like machines.-The body 1 and handle 2 of the machine shown are similar in form to those of a laundry iron, and the body is carried by wheels 77 mounted in lugs on a bottom plate 3 and a frame web 6. The stitch-forming devices comprise a curved needle 31 clamped to a sector 32 on a rock-shaft 33, actuated by a crank-pin 38 engaging an eccentric cam-slot in a disc 40 on the main shaft 7, and a forked looper 62 resting in a slot 74 in a frame web 36 and pivotally connected to a rod 64 which slides and swivels in a guide 65 under the action of a rotating crankdisc 66 driven through bevel gears from the main shaft 7; the edge of the slot 74 supporting the looper is of cam form giving the looper a rise and fall during its lateral oscillation. The forward part of the bottom plate 3 is formed with a slot 43, and a comb-like device 45, Fig. 2, is moved downwardly and laterally through slots in the plate 3 to engage the work and push it so that a ridge is raised in the slot 43 for engagement by the needle. The pusher 45 is carried by a rod 46 mounted at its middle in a bearing 59 allowing angular play and connected for actuation at its rear end to an arm 53 on the strap 51 of a ball-bearing eccentric 50 on the main,shaft-7, the strap 51 being guided by a pin 54 on a post 52 thereon engaging vertical slot in a frame web 5; the middle bearing 59 of the pusher-rod is mounted on a slide adjustable laterally. by hand in a guideway 60. Feed by moving-machine.-The axles of the wheels 77 carrying the machine are bevel-geared to a longitudinal shaft 95 driven intermittently through a one-way clutch 82 actuated from the post 52 of the eccentric strap 51 through a lever 87 which follows the contour of the body 1 and is mounted on a pivot carried by the body ; the pivot is slidable on the lever 87 and is adjustably clamped in a slot 92 in the body to enable the amplitude of movement of its lower end, which determines the feed stroke, to be varied. The machine may be moved by hand, the main shaft 7 then being driven from the wheels 77. Starting and stopping.-In the machine shown the main shaft 7 is driven by an electric motor 8, controlled by a switch 23, through a clutch comprising a disc 11 on the shaft 7 and a disc 13 rotating with the shaft of the motor but slidable thereon under the action of a spring-pressed lever 17 connected to a grip member 14 in the handle of the machine. The lever 17 carries balls 19 to press the clutch disc 13 into the driving position and a nose 22 engaging a groove in the disc 13 to retract it. When the machine stops the needle is brought into a retracted position by a #-shaped member 41 having pins at its ends engaging a concentric groove 39 in the disc 40 and formed with an upward extension acted on by a tension spring 42; in a modification the spring is replaced by an electromagnet which is energised when the grip 14 is released.