GB703821A - Improvements in or relating to sewing machines - Google Patents

Abstract

703,821. Sewing-machines. CULLINANE, W. J. April 9, 1952, No. 9142/52. Class 112 A sewing-machine has a detachable needle bar which carries a thread spool and is releasably connected to the needleoperating mechanism of the machine. A detachable needle-bar, assembly for such a machine may comprise an end cover plate removably secured to the head of the machine and slidably supporting the needle-bar. Several needle-bars and looptakers may be mounted so as to be selectively connected to the machine. Chain-stitching; lock-stitching; threadspool holders; frames.-In the machine shown, the needle-bar 21 slides in a block 21a fixed on the inner surface of a faceplate 31 which is detachably secured to the head 4 of the machine frame by a pair of arms (not shown) engaging spring catches on the frame; the upper and lower edges of the head 4 are notched as at 30 to clear the needle-bar. A rod 17 reciprocated vertically in the head 4 by the usual disc crank 15 carries arms 19, 20 with cup-shaped recesses to receive the rounded ends of the needle-bar, the end of the lower arm being slotted into the recess to clear the needle; the upper arm 20 is resilient, so that the needle-bar is easily engaged with the arms 19, 20 and thus operated with the rod 17. The needle-bar carries a thread-spool 24 ,and a bracket 23 supporting a thread guide 26 and a tension device 25; a second tension device 33 is mounted on the plate 31. In a modification, the needle-bar carries an arm projecting through a slot in the faceplate 31 to receive the thread-spool, which is of the spring-controlled encased type so that the parts 23, 25, 26 are not required. Several needle-bars may be supported in a cage mounted for rotation on a vertical axis to bring them selectively into position for engagement with the carrier 31, and in a lock-stitch machine corresponding shuttles may be mounted in a similar cage connected to that carrying the needle-bars. Driving.-An electric motor 5 housed in an enlarged part of the standard of the machine, drives the needle-bar shaft and the loop-taker shaft 9 through separate belts from opposite ends of its shaft. Feed-dogs.-The work-engaging surface of the feed-dog is formed of rounded corrugations instead of sharp teeth, to avoid damage to delicate fabrics. Presser-feet.-The presser-foot is preferably transparent, so that the whole of the work is visible. Throat-plates.-The needle-bar aperture in the throat-plate is of key-hole shape, and lies between two feed-dog slots. Specification 669,913 is referred to.