GB971862A - Improvements in or relating to stitch controls for plural-feed sewing machines - Google Patents

Abstract

971,862. Sewing machines. G. M. PFAFF A.G. July 30,1963 [Aug. 1, 1962], No. 30115/63. Heading D1G. A sewing machine comprising an adjustable feed dog and a pair of auxiliary feed rollers is provided with means having a lost-motion connection with the feed-adjusting means and being adapted for operation against spring bias first to move the rollers apart and then to change the feed from the forward to the reverse direction. A positivelydriven lower feed roller co-operates with an upper feed roller journalled at the lower end of a rod 8, the upper end of which is slidable in a sleeve 9 adjustably screwed into the machine frame. A spring 13 biases rod 8 downwardly. A feed dog 16 is carried by a bar 17, one end of which is forked to embrace a feed-lift eccentric 29 on a rotary shaft 28, and the other end of which is pivoted to an arm 20 on a transversely-slidable pin 19. The latter is connected by a link 21 to a pin 22, which is connected by a link 23 to a pin 24. A journalled shaft 39 carries a crank 42 and a crank pin 41, the latter being connected by a link 43 to pin 24. A rotary shaft 25 carries an eccentric 26 coupled by a pitman 27 to pin 24. The arrangement is thereby such that when shaft 39 is adjusted to align pin 41 with pin 22 no feed occurs, while progressive angular displacement of pin 41 from pin 22 in one or the other direction results in increasing rates of forward and reverse feeds respectively. A crank 40 on shaft 39 is connected by a link 38 to one arm of a double-armed lever 34 rigid with a journalled shaft 33. The bell end 35 of the other arm of lever 34 is biased by a spring 57 into engagement with a cam surface 30 on a pivoted feed control disc 32 governing forward feed. A crank 48 on shaft 44 is biased by a spring 61 to position a crank 46 on shaft 44 below a lug 47 fast with rod 8. Crank 48 is pivoted to a bar 50 which is connected by a pivotal link 58, a slidable rod 59 and a chain 60 to a pedal. A pin 51, slidably mounted in bar 50, is biased downwardly by a spring 52 to project into a longitudinal slot 53 formed in bar 50. A pin 54, projecting transversely into slot 53, is carried by a crank 55 on shaft 33. The arrangement is such that when said pedal is operated to lower bar 50, crank 46 first engages lug 47 to lift rod 8 and the upper feed roller, when pin 56 then engages pin 54 for turning shaft 33 to transfer end 35 to a cam surface 31 of disc 32 governing the reverse feed.