GB435303A - Adjustable eccentric for sewing machines - Google Patents

Abstract

435,303. Sewing-machines. SINGER MANUFACTURING CO., Elizabeth, New Jersey, U.S.A. March 11, 1935, No. 7494. Convention date, July 17, 1934. [Class 112] [See also Group XXVI] A variable throw eccentric, particularly for use in the feed mechanism of a sewing-machine, is secured to its shaft with provision for crosswise adjustment by a cam rotatably mounted on the shaft and engaging a projection on the face of the eccentric, relative movement of the cam and eccentric being normally prevented by a spring- pressed, manually operable detent on the cam which engages an internal arcuate rack on the eccentric, the rack having a centre of curvature noncoincident with the centre of curvature of the periphery of the eccentric. The invention is described as applied to a lower four motion type of dog feed, a visible index on the eccentric indicating the length of stitch. The eccentric 35 has an enlarged bore 36 and is fitted with a flange 37 having two radial slots 38 through which pass two studs 39 screwed into a belt pulley 26 on a driving-shaft 5. The studs 39 also pass through concentric slots 42 in a plate 41, Fig. 6, having a cam slot 46 engaging a roller 45 on a pin 44 on the eccentric. Spring washers 43 prevent axial movement of the eccentric and cam plate. The cam plate 41 has radial bore 55 for receiving the shank 56 and spring 60 of a detent 57 which engages a rack 59 formed in a recess 58 in the eccentric. To effect adjustment, a lever 49, Fig. 2, is moved to press its hooked end 48 into a notch 47 formed in the plate 41 at the end of the bore 55 so as to hold the plate against rotation and also move the detent 57 out of engagement with the rack 59. Rotation of the shaft 5 then causes the cam slot 46 to shift the eccentric radially. Index numbers are marked on the edge of the flange 37. Fig. 8 shows a modification in which an eccentric 61 has projections 65 engaging a diametral groove 66 in a disc 67 secured to the shaft, the opposite face of the eccentric having a roller 69 and arcuate rack co-operating with a cam plate, similar to the cam plate 41 and held in position axially by a collar 64.