| 摘要 |
589,995. Sewing-machines. SINGER MANUFACTURING CO. April 7, 1945, No. 8646. Convention date, Jan. 1. Drawings to Specification. [Class 112] Lock-stitching by hooks; presser-bars; frames. -In order to improve high-speed stitching by reducing the pressure of the under-thread against the needle-hole in the throat-plate and thus its friction against the needlethread and the resistance to feed of the work, the needle-bar of a straight eyedneedle machine is inclined so that the descent of the needle has a forward component; the needlehole can thus be more nearly above the rear edge of the bobbin-case, from which the underthread emerges, while the needle still passes through the axis of the loop-taker. The presser bar is substantially parallel to the needle-bar. The whole standard and arm of the machine may be inclined, thus facilitating inspection of the work, or the inclination may be confined to the head or to the guides for the needle-bar and presser bar. Feed by dogs.-In order,to provide additional clearance near the loop-taker in the usual fourmotion feed mechanism comprising arms on two horizontal rock-shafts, the feed-lift rock-shaft carries a forked arm engaging a block on the feed-bar, instead of the usual arrangement in which the feed-bar is forked. The arm on the feed rock-shaft is arranged so that it never reaches the vertical position, the rear-end of the feed-dog being thus made to rise before the front end and to drop quickly near the end of the feeding movement. ' Upper and lower shafts, connecting; lubricating.-The two shafts are bevel-geared to a vertical shaft, the gearing giving a two-to-one ratio. The bevel gear on the lower shaft also engages a bevel gear on the shaft of a rotary oil-pump which supplies the bearings of the machine. Specification 452,001 is referred to. |
