SE303666B - - Google Patents

Abstract

1,110,680. Ratchet gearing. G. M. PFAFF A.G. 3 April, 1967 [6 April, 1966], No. 16118/67. Heading F2Q. [Also in Division D1] A shaft carrying one or more control cams is turned into consecutive angular operating positions by means comprising a ratchet mounted on said shaft, a pawl operated towards and away from said ratchet over a stroke normally insufficient to effect actuation of the ratchet, and manually-operable means for displacing the ratchet by a predetermined angle so as to enable actuation and rotation of the ratchet by the pawl from one to the next operating position of the shaft. A shaft 27 in a zig-zag sewing machine carries a ratchet 29 and cams 16, 26, 28 controlling the stitch width, stitch position and work feed respectively. A lever 45 carries a roller 47 biased by a spring 49 against a cam 46 on a shaft 4 for oscillating lever 45 once at each revolution of shaft 4 when the needle is wholly above the work. A pawl 44, pivoted to lever 45, is biased by a spring 48 against ratchet 29, the stroke of pawl 44 being less than the pitch of the teeth 42 of ratchet 29. A pawl 50, pivoted to one arm of a lever 51, is biased by a spring 58 against ratchet 29. The other arm of lever 51 carries a handle 52 and also carries a lug 53 biased by a spring 57 against a fixed abutment 55. For turning shaft 27 from one operating control position to the next one, handle 52 is actuated to engage lug 53 with a fixed abutment 54, and thereby to turn ratchet 29 just sufficiently to enable pawl 44 to engage a tooth 42 on its next forward movement.