GB732295A - Improvements relating to sewing machines - Google Patents

Abstract

732,295. Sewing-machines. SCHWAB, M. April 29, 1953 [April 30, 1952], No. 11823/53. Class 1.12. The direction of stitching in a sewing-machine is reversed by means of an electromagnet, preferably controlled by a knee-lever and acting on the usual feed-control means. The invention is described in connection with a machine having an auxiliary slow-speed drive automatically brought into action before stopping, and provision is made for sewing a few stitches forwards and then backwards before stopping, to secure the end of a seam. In the arrangement shown, an auxiliary electric slow-speed drive circuit is connected to terminals 28, and power is applied to terminals 30 automatically when the main drive is put out of action by a control treadle which also actuates a selector switch 15 to determine whether power is fed to the auxiliary drive from the upper or lower contact of a switch 14 rotating with the machine, one of these contacts being opened when the needle of the machine is in its upper position and the other in the lower. When slow-speed stitching is required before stopping, the rotary switch 19 is moved clockwise by means of a knee-lever to the position shown, which is determined by a detent 191 engaging a notched disc: in this position the contacts 22, 23 are connected so that the auxiliary drive is fed from both contacts of the switch 14 and therefore runs continuously until the rotary switch 19 is moved another step, when the machine stops. A further step of the switch results in energization of the feed-reversing electromagnet 35 through contact 33, and restarting of the continuous slow drive by the contacts 24, 25. The switch is returned to its initial position by a spring 37 when released. The electromagnet 35 may be connected to the feed-reversing lever directly or by a chain or cable passing round a pulley.