GB808860A - Improvements in or relating to sewing machines - Google Patents

Abstract

808,860. Sewing machines. PFAFF, A.G., G. M. July 23, 1956 [Aug. 9, 1955], No. 22662/56. Class 112 A reciprocating cutter bar 13, which carries a cutter 14 adapted for trimming the work along the line of feed, is biased to the raised and inoperative position by a spring 16, and a control member, such as a treadle, knee press or magnet, is connected to an operating rod 56, the arrangement being such that alternate operation of the control means in the same direction serves respectively to connect the cutter bar to a drive, and to disconnect the cutter bar therefrom. An oscillating shaft 22, driven by connections 19, 20 from the arm shaft of the machine, carries a crank 23 provided with a sleeve 24 in which is slidably mounted a pin 25. The latter is spring biased towards the front edge 28 of the cutter bar, and is thereby adapted, when the cutter bar is depressed, to enter a notch 26 in edge 28 for establishing a driving connection with the cutter bar. Bush 24 is embraced by the forked lower end 44 of a lever 42 which is pivoted at 43 and is normally maintained in a neutral position by a spring 47. A plunger 35, slidably mounted in the upper end of the cutter bar, is biased by a spring 37 to carry a pin 38, projecting transversely from the plunger, to the closed end of a slot 39 in the upper edge of the cutter bar. The plunger is located opposite the upper end 46 of lever 42 when the cutter bar is in the inoperative position. One arm 51 of a control lever, pivoted at 49, has connected thereto a rod 52 biased downwardly by a spring 53. One arm of a lever 55 underlies the end of rod 52 and the other arm is connected to the operating rod 56. The other arm 57 of the control lever has a cranked end 58 which is disposed transversely across the top of the cutter bar and in front of the projecting pin 38 when the cutter bar is raised. Operation of the control member serves to draw rod 56 downwardly and thereby to rock the control lever in the clockwise direction, Fig. 1, whereby end 58 moves downwardly and reacts with the upper edge of the cutter bar to depress the latter to the operative position. End 58 simultaneously reacts with pin 38 for moving plunger 35 outwardly into engagement with the end 46 of lever 42, whereby the latter turns anticlockwise, Fig. 2, till plunger 35 rides off end 46, when the latter is moved by spring 47 into engagement with an angle member 60 provided on end 58. After operation of the control member ceases, end 58 returns to its original position above end 45. The cutter bar continues to operate till the control member is again operated, when end 58 moves downwardly to carry member 60 into engagement with the upper edge of end 46 to turn lever 42 in the clockwise direction, Fig. 2, whereby the forked lower end 44 of lever 42 engages a nut 27 on pin 25 to withdraw the latter from notch 26, and spring 16 then raises the cutter bar to the inoperative position.