GB869637A

GB869637A - Improvements in or relating to the looper drive for double chain stitch sewing machines

Info

Publication number: GB869637A
Application number: GB33954/57A
Authority: GB
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1956-11-02
Filing date: 1957-10-31
Publication date: 1961-06-07

Abstract

869,637. Sewing machines. PFAFF A. G., G. M. Oct. 31, 1957 [Nov. 2, 1956], No. 33954/57. Class 112 The needle-evading movement provided by the looper driving mechanism of a double chain stitch sewing machine having needle and base feeding means is composed of a constant movement on which is superimposed a variable movement dependent upon the advancing movement of the needles. The invention is described as applied to a two needle, feed-off-the-arm machine. The feed dog 20 on its feed-bar 22 receives lifting movement from a link 52 connected to one end of a lever 50 pivoted at 51 to the arm 5, the other end of which is oscillated by a pitman from an eccentric 48 on the shaft 6. Feed advance movement is given to the feed-bar through a link 26, pivoted at 67 to the arm 27 of a bell-crank 28. The other arm 33 of the bell-crank is oscillated by a pitman 34 from an adjustable eccentric 35 mounted on the shaft 6. The loopers 53 are carried on a looper shaft 57 which is oscillated, to provide a loop entering motion, by a crank 58 driven from the shaft 6. A bellcrank 65 also pivoted at 67 to the arm 27 of the bell crank 28 has one arm 64 engaged with claws 61 on the shaft 57 to provide the needle avoiding reciprocation of the shaft, the motion of the bell crank due to the adjustable movement of its pivot 67 being combined with a constant oscillation of the bell crank derived from a pitman 70 and an eccentric 71 fixed to the shaft 6. The swinging movement of the needles in the sewing direction is derived from a lever 18 connected to an adjustable eccentric 12 by a pitman 17. To synchronise the needle swing with the feed dog movement the cam setting members 13, 36 are provided with grooves 14, 37 which may be aligned with each other by engaging, respectively, the detents 16, 38 on a bridge 15. The bridge is normally urged away from the members by a spring 44, but may be depressed into engagement by a push button 47.