GB1002888A - Improvements in or relating to stitch control mechanisms for sewing machines - Google Patents

Abstract

1,002,888. Sewing machines. G. M. PFAFF A.G. July 16, 1963 [July 18,1962 ], No. 28044/63. Heading D1G. [Also in Division F2] In a sewing machine having needle feed and feed by dog adjustable simultaneously, the means for controlling the needle feed is provided externally of the machine casing under the hand wheel or flywheel of the machine, and comprises a crank on a rock shaft extending into the machine casing to impart needle feed movements, and a second crank on a shaft extending into the machine casing and linked with the means for effecting feed dog adjustment. The pivoted needle bar gate is oscillated by a rock shaft 24 which is connected via a crank 23 to needle feed control mechanism 10 situated externally of the machine frame under the flywheel 42 on the arm shaft 2. Crank 23 is pivoted to a pin 22 on one end of a link 21 pivoted on a pin 18 bridging the arms of a yoke 16. The latter is pivoted by pins 17, 17a to a yoke 15 rigid with a rock shaft 14. Pin 18 is connected by a pitman 20 to an eccentric 19 on shaft 2. The arrangement is thereby such that whn pins 17 and 17a are aligned with pin 22, crank 23 remains stationary on oscillation of yoke 16, and is oscillated with increasing magnitude where pins 17, 17a are progressively moved away from alignment with pin 22 by rotation of shaft 14. The feed dog advance shaft 36 carries a crank 35 converted by a linkage 30, 31, 32, 33, 34 to a crank 28 on a rock shaft 29. Pin 32 is connected by a pitman 39 to an eccentric 38 on the looptaker driving shaft 9. The arrangement is thereby such that when pins 30 and 34 are aligned, crank 35 remains stationary or oscillation of links 31, 33, but is oscillated with increasing magnitude when pin 30 is progressively moved away from alignment with pin 34 by rotation of shaft 29. One arm of a double-armed crank 42 on shaft 29 is connected by a link 41 to a crank 40 on shaft 14. The other arm of crank 42 is connected by a link 43 to one end of a lever 44 rigid with a pivoted shaft 45. The other end of lever 44 is disposed in a cam slot 46a formed in a rotary control disc 46, and is biased by a spring 47, acting on shaft 29, against the outer edge of slot 46a governing the forward feed. Rotation of disc 46 from the zero feed position shown thereby progressively increases the rates of needle and dog feed simultaneously. Shaft 45 may be rotated at any time by a handle 48 to position lever 44 on the inner edge of slot 46a controlling the reverse feed.