GB940668A - Improvements in or relating to differential feed controls and indicator mechanisms for sewing machines - Google Patents

Abstract

940,668. Sewing machines. G. M. PFAFF A. G. July 18, 1962 [July 19, 1961], No. 27530/62. Heading D1G. A sewing machine having main and auxiliary feed dogs, the strokes of which are controlled by the angular position of respective setting shafts, comprises a pair of rotatable and concentric control shafts respectively coupled to the control shafts, control means adapted to effect synchronous adjustment of the setting and control shafts, first stop means fixed relatively to one control shaft, co-operating second stop means adjustable relatively to the second control shaft for varying the relative strokes of the dogs, and co-operating scale and indicator means carried by the respective stop means to indicate the feed differential. A control shaft 3, rotatably mounted in the sewing machine standard, carries a crank 6 connected by a link 7 to one arm of a double-armed lever 9 rigid with the stroke-setting shaft 8 for the auxiliary feed dog. A hollow control shaft 19, journelled on shaft 3, carries a two-armed lever 21, one arm of which is connected by a link 22 to one arm of a two-armed lever 24 on the stroke-setting shaft 23 for the main feed dog. The other arms of levers 9 and 24 are interconnected by a tension spring 29. The other arm of lever 21 has a follower member 28 co-operating with a cam surface 26 on a rotatable disc 27. A U-shaped stop member 11, pivoted on shaft 3 carries a pair of L-shaped pivoted arms 15 biased by an interconnecting spring 16 into engagement with opposite sides of an abutment 4 on shaft 3 for coupling the latter and member 11 together. A pair of opposed stop screws 12, 13, carried by member 11, are adapted to engage opposite sides of a stop abutment 18 on shaft 19. The arrangement is thereby such that rotation of disc 27 serves to adjust the strokes of the dogs simultaneously. The angular position of member 11 may be varied by adjustment of screws 12,13 for varying the stroke of the auxiliary feed dog alone. A pointer 20 on abutment 18 co-operates with a scale 20 on member 11 to indicate the feed differential. A lever 10 on shaft 3 may be depressed to reverse the feed, normal feed being restored on release of lever 10 by a spring 25 acting on shaft 3.