Patent GB-190817704-A (GB)
Title: Improvements in or relating to Machines for Blind-stitching, Blind Felling, and like Sewing or Stitching.
Inventor: BROWN JOHN ARTHUR
Filed: 1908-08-24
Granted: 1909-07-29
Abstract: 17,704. Brown, J. A. Aug. 24. Blind-stitch sewing-machines feed; presser feet; presser lifted automatically.-In a blind-stitch sewing-machine the feed is divided into two parts, and arranged to operate in conjunction with a clamp which holds the work in position during the return movement of the feeding-devices. The lower feeddog 11, Fig. 4, is mounted as usual on a carrier 9 on a feed-traverse shaft 2, and is given its lifting movement by an eccentric 10 on the lower driviugshaft f, which is driven from the upper shaft e through cranks h and rods g, a spring 20 serving to return the dog after actuation. The traverse shaft 2 is driven from an eccentric 3 on the shaft e by a forked lever 4 attached by a link 6 to a lever 7 pivoted to the arm b. The top feed-dog 14 is mounted on a carrier 8 on the feed-rising shaft m, which is driven from the shaft e by a forked lever o embracing an eccentric q thereon, the lever o being similarly attached by a link w to a lever x, pivoted to the arm b and attached to a loose stitcbregulator y operated by hand or treadle, while the top feed-rising shaft r is driven by a lever t, the upper end of which forms a strap u on a second eccentric v on the shaft e. The dog 14 is raised when an arm 13 on the shaft r contacts with a projection of the feed-carrier. A double-ended lever 15 carries at its upper end a work clamp 16 serrated on its under side and working in a recess of the dog 14. The lower end 17 of the lever 15 is made elastic and is bent so that it is also acted on by the arm 13 of the shaft r to raise the clamp 16. The arm 13 thus raises the clamp 16 when the dog is held down by the spring 21, but allows the spring 19 to hold down the clamp when the dog 14 is raised for the return movement. The end 17 is made elastic to allow for varying thicknesses of work. To allow for adjustment of the position of the dog 14, the shaft m has a slot 29, Fig. 7, at one end, and on opposite sides of this slot act screws 31, 32 mounted in the boss 30 of the lever n, by which the forked lever o is attached. The material is passed between the two dogs and turned back over the upper one. The dogs may be reciprocated at the same or different speeds and may traverse the same or different distances according to whether any fullness is required in either the top or the bottom fabric. For varying the traverse, the bell-crank lever x is regulated by a screw y acting on a cone z, which slides in a slot z<1> so that a given amount of movement is imparted by the treadle. The inward movement of the cone z compresses a spring z<2> on the screw y against the end of the bell-crank lever x. The traverse of the lower dog may be similarly regulated from the lever 7. If it is desired to remove one of the layers of the fabric out of the needle-path, say at every alternate stitch, a plunger 22 is used, the plunger being pivoted to a link 34 pivoted to the machine arm and attached to the presser-bar 35 by a link 36. The plunger can thus rise and fall with the presser-foot, and is prolonged at its upper end 27 for connexion by a link 23 to a slotted lever 24 pivoted to the arm, an oscillating movement being imparted to the lever 24 by a cam 25 on the shaft e. When, instead of this plunger movement, a zig-zag stitch is required, a screw 28, which holds the end 27 in a slot 26 of the link 23, is released to allow the link to slide without operating the plunger.