Patent GB-190807544-A (GB)
Title: Improvements in or relating to Sewing Machines.
Inventor: BROWN JOHN ARTHUR
Filed: 1908-04-06
Granted: 1909-04-06
Abstract: 7544. Brown, J. A. April 6. Sewing-machine feed. - Arrangements for reversing the feed and regulating the length of stitch comprise means for moving the eccentric on the main shaft that operates the feed traverse shaft relatively to the main shaft, the operation being effected from a treadle or the like to a predetermined extent in either direction to determine the length of stitch. In one form, an eccentric k, Fig. 2, on the main shaft g, which may or may not be provided with a sliding block l, imparts motion to the feed traverse shaft e through a connecting- rod or forked lever n and an arm m. A bell-crank lever p is pivoted to the frame by a pin immediately behind a pin t, by means of which a link s connects the forked lever n to one arm of the bellcrank lever p. The other arm of the bell-crank lever p is connected by a rod q to an operating- treadle or the like, which can thus move the forked lever n so that the pin x is on either side of the line u, u through the centres of the shaft g, the pin t, and the pivot connecting the lever n to the arm m. This movement effects the reversal of the feed, and its extent determines the length of stitch. The extent of the movement is determined in each direction by the position of stops y, z, which are operated simultaneously by a stitchregulator lever 1. The lever 1 works over a scale fixed on the head of the machine, and is clamped in any position against the sides of the slot 6 in which it works by means of a screw 7. In a modified form of stitch regulator, the stops are formed by projections on two nuts operated by a right and left banded screw, which is manually rotated to set the stitch. A dial plate carrying numbers indicating the size of stitch is rotated with the screw, and one number at a time is visible through an aperture. In a modified form of stitch reversing and regulating device, shown in Figs. 3 and 4, the connecting-rod n is attached to a strap n<1> surrounding the eccentric k on the main shaft g. A disk 42 fixed to the main shaft is connected by a bolt 43 provided with a tapering head to a lug 44 of a plate 45, to which the eccentric k is fixed. A cam-shaped hole is cut in the eccentric k, and pins 47, 48 pass through the eccentric into the hollow shaft g and bear against an inclined portion 29 of a rod 25, which slides inside the hollow shaft g. Recesses 27, 28, Fig. 8, are formed in the rod 25 (which may be formed in several portions as shown) to form the inclined portion 29. The centre of the eccentric is moved across the centre line connecting the centre of the main shaft g, Fig. 3, with the centre of the pin connecting the arm m on the feed traverse shaft e with the connecting-rod, to reverse the feed by sliding the rod 25 in the shaft g. The inclined portion 29, Fig. 4, then bears against the pins 47, 48, and moves the eccentric across the line of centres. The rod 25, Fig. 8, is slotted at the end, and a pin 30 is passed through the slot to prevent the rod from rotating inside the hollow shaft g, Fig. 3. The rod 25 is moved longitudinally against the action of a spring 41 by a bell-crank lever operated by a treadle, or by a sliding rod 32 having a projection 31 and operated by a lever 35, which is actuated from the treadle. The stitch-regulating device, which determines the extent of motion of the rod 32 in each direction, comprises a screw 54, Fig. 9, with a flat tapered head 55, which moves in a similarly-shaped slot 56 in the rod 32. The screw 54 is moved by actuating a circular nut 51, which is provided with recesses and numbers on its periphery and rotates in a slot 50 in an extension 49 of the bearing 33 for the sliding rod 32. The tapering edges of the head 55 act as a fixed stop for limiting the sliding movement of the rod 32. In another modification, the eccentric k, Figs. 14 and 15, is mounted between collars 42, 59 and has flanges k<1>, 58, and the hole 60 is formed in the eccentric. A pin 63 passes through a slot 62 in the shaft g and through an inclined slot 61 in the rod 25, so that the sliding movement of the rod 25 moves the eccentric across the line of centres and reverses the feed. In another form, the inner end of the rod 25 may be wedge-shaped, and acts upon a screw which passes through the shaft and eccentric.