GB1530162A - Sewing machines - Google Patents

Abstract

1530162 Sewing machine SPECIAL SEWING SYSTEMS Inc 31 Oct 1975 {12 Dec 1974] 45126/75 Heading D1C A sewing machine is provided with a pair of needle bars each including a needle carrying member which is axially movable therein, under pneumatic control, between positions in which the needle is effective and ineffective respectively to form stitches. The needle bars 36 are joined at their lower ends by a needle clamp 52 and reciprocate together. Each bar contains a detent bar 106 secured to the bar at 54 and slidably receiving a cam member 92 provided with a piston rod 86 and piston 84, and a needle holder 102 provided with transverse passages 116, 118 carrying detent balls 98, 100 controlled by the cam faces 94, 96 on member 92. Passages 66<SP>1</SP> and 80 may each be selectively connected to an air supply or exhaust to introduce air pressure above or below piston 84 to move the cam member and needle holder either down into an operative position in which it is secured by cam face 96 forcing ball 100 into a lower recess 136 in the detent bar 106 or upwardly to the inoperative position shown for the left bar in Fig. 3, the needle holder 102 being held in this position by the action of cam face 94 in forcing ball 98 into the upper recess 134 in the detent piece 106: Air is supplied to the needle bars through respective four way valves (162, 162<SP>1</SP>, Fig. 7 not shown) and hoses (60, 76) connected to the needle bars. The bobbins (166) of the valves are actuated by pedals (Figs. 8 and 9 not shown) one pedal being provided for each valve. The needle bars are mounted in a frame (38, Figs. 1 and 2 not shown) pivoted (at 40). to be swung, by a link (44) from a hollow rock shaft (SO), in the work feeding direction. The needle bar drive is derived from a crank (26) on the main shaft (20), a link (30) connecting the crank pin (28) to a pin (32) on. a collar (34) secured to the right needle bar.