GB338032A - Sewing machine - Google Patents

Abstract

338,032. Fairweather, W., (Singer Manufacturing Co.). Dec. 16, 1929. Feed by dogs; chainstitching.-In machines of the cylinder-bed chain-stitch type, the main shaft 8 extends about half way into the bed 4 and the four-motion feed-dogs 21 are carried by an inverted U-shaped yoke the legs of which are pivoted in crank arms fixed to a feed lift rock shaft extending the whole length of the bed. The main shaft 8 rotates in bearings 5, 6, 7 and has a crank 10 for actuating the pitman 11 to rock the usual needlebar reciprocating shaft 14 in the usual way. The presser-foot 19 is carried by the usual downwardly pressed bar 20. Four-motion feeddogs 21 co-operate with the presser foot to feed the work across the cylinder bed 4, and are re-mounted on the inverted U-shaped yoke 22 which is pivoted by pins 24 in the arms 25 of the feed-lift rock shaft 26 This shaft extends into the standard 1 and has affixed a crank arm 27 connected to the strap 29 of the main shaft eccentric 30, whereby it derives its rocking motion to impart lift to the feed dogs. The feed advancing motion is imparted to the dog by a short rock shaft 31 in the bearing 5, actuated by the main shaft eccentric 35 and pitman 34. The rock shaft is connected to the yoke 22 by an arm 40 carrying an adjustable pin 39 engaging a slot 37 in the crank arm 36. The arm 40 is clamped to a pin 42 on a rocker arm 43 which fits a block 45 pivoted on a pin 46 on the yoke 22. These arrangements allow the pin 39 to be aligned with the pivots 24, and to adjust the feed dogs to a central position in the feed-slots of the throat plate. The loopers 47 are carried on the shaft 49 and driven by the links 55, 54, 52 to synchronize with the needle movements and bv the pitman 61, in the manner described in Specification 337,661. The looper threads are controlled by the levers 67, 69 in the manner described in Specification 338,033.