GB773451A - Improvements in and relating to a sewing machine - Google Patents

Abstract

773,451. Sewing machines. SOC. DE L'USINE DE LA MARQUE. March 23, 1955 [March 24, 1954], No. 8434/55. Class 112. Frames. Driving. Connecting upper and lower shafts.-The frame of a sewing machine comprises a U- shaped vertical plate 4, the arms of which are horizontal and which is carried by a base 1, and the stitchforming and work-feeding mechanisms are disposed on one side only of the plate, the rotary driving shafts for said mechanisms passing through the plate and being rigid with driving devices situated on the other side of the plate. The frame is enclosed in a housing comprising a pair of members 57, 58. The shaft 25 of an electric motor 26, mounted on the base, carries a pulley 24 which is connected by a belt 23 to a pulley 21 fixed to a main driving shaft 22. The latter carries a main driving sprocket 40 for an endless driving chain 41, and also serves to actuate the feed dogs 9. Chain 41 connects sprocket 40 to sprockets 42 and 43 on the lower arm, and also to sprockets 47, 56 and 50 on the upper arm. Sprocket 42 drives the rotary hook 7, and sprocket 50 drives the needle bar 32 and thread take-up 38. Sprockets 43, 47 and 56 idle, sprocket 43 being carried by a shaft 44 slidably mounted in a slot 45 for tensioning the chain. The sprockets are angularly adjustable on their respective shafts. Feed by dogs.-The feed dogs 9 are carried by a feed arm 10 which is engaged in an axial slot 11 formed in a pivoted, horizontal pin 11, arm 10 also being pivoted to pin 11 about a vertical axis 11 b. A roller 13a, which depends from arm 10 and engages an inclined slot 13 in a reciprocating block 12, serves to impart feed-advance movement to arm 10. Block 12 is guided by a pin 14 slidable in a bracket 15, and is reciprocated by a rod 16 which is carried intermediately on a laterally slidable pivot 17 and has a forked end embracing a cam 19 carried by shaft 22. Feed-lift movement is imparted to arm 10 by a roller 31 carried by a lever 26a which is pivoted intermediately at 27 to one end of a bell crank lever 28, and which has a forked end embracing a cam (not shown) carried by shaft 22. The other arm of lever 28 carries a handle 30 by which lever 28 may be rocked about its fulcrum 29, whereby arm 10 may be lowered to an inoperative position. Stitch-forming devices.-The rotary hook 7 is driven by a shaft 8 on which sprocket 42 is mounted. Shaft 35, on which sprocket 50 is mounted, carries a crank 34 connected by a rod 33 to the needle bar 32. Sprocket 50 carries a crank pin 52 in which is slidably mounted the outer end of a rod 53 fixed at its inner end to a shaft 39 which also carries the thread take-up 38, whereby oscillatory movement is imparted to the latter. Specification 676,073 is referred to.