Device for uniform regulation of forward and reverse stitches in automatic button hole stitching by means of a zigzag sewing machine

Claim 1

IN A ZIGZAG SEWING MACHINE HAVING AN AUTOMATIC CAM AND A CAM FOLLOWER, WHEREIN HOLE STITCHING IS CARRIED OUT BY ONE REVOLUTION OF SAID AUTOMATIC CAM WHICH AUTOMATICALLY CONTROLS THE AMPLITUDE, FORWARD AND REVERSE STITCHES AND NEEDLE POSITION LINE, SAID AUTOMATIC CAM HAVING A FORWARD STITCH CAM PORTION FOR CONTROLLING FORWARD STITCHING AND REVERSE STITCH CAM PORTION FOR CONTROLLING REVERSE STITCHING, A STITCH REGULATING MECHANISM COMPRISING A FORKED FEED ROD, A MANUAL FEED REGULATING CAM, AND A STITCH BELL CRANK FOR TRANSMITTING A REGULATING MOTION TO SAID FORKED ROD IN THE STITCH REGULATING MECHANISM, SAID MANUAL FEED REGULATING CAM AND STITCH BELL CRANK BEING SEPARATELY ARRANGED SIDE BY SIDE IN CONTACT WITH EACH OTHER, A COMMON SHAFT MOUNTING SAID FEED REGULATING CAM AND SAID CRANK SO THAT THE REGULATED DISPLACEMENT OF SAID MANUAL FEED REGULATING CAM IS TRANSMITTED TO SAID FORKED ROD, MEANS TO CAUSE SAID STITCH BELL CRANK TO CONTACT UNDER ELASTIC PRESSURE SAID MANUAL FEED REGULATING CAM SO AS TO BE URGED ELASTICALLY IN A FORWARD SEWING DIRECTION WHEN THE REVERSE STITCH CAM PORTION OF SAID AUTOMATIC CAM AND STITCH CAM FOLLOWER ARE IN CONTACT WITH EACH OTHER, A LINK MECHANISM COMPRISING AN INTERMEDIATE CRANK AND TWO CONNECTING RODS FOR OPERATING SAID STITCH BELL CRANK WITHOUT BEING RESTRAINED BY SAID MANUALLY OPERATED STITCH REGULATING CAM THEREBY TO CONTROL PITCH OF REVERSE STITCHING BY SAID REVERSE STITCH CAM PORTION OF THE AUTOMATIC CAM; SAID AUTOMATIC CAM FORWARD STITCH CAM PORTION BEING CONSTRUCTED SO THAT WHEN THE FORWARD STITCH CAM PORTION OF THE AUTOMATIC CAM AND THE STITCH CAM FOLLOWER ARE IN COMPLETE CONTACT WITH EACH OTHER THE PITCH OF THE FORWARD STITCHING IS ALWAYS LARGER THAN THAT OF THE REVERSE STITCHING, A STITCH ADJUSTING KNOB ROTATABLY MOUNTED AND OPERABLY CONNECTED ELASTICALLY TO SAID STITCH BELL CRANK THROUGH SAID MANUAL FEED REGULATING CAM FOR ADJUSTING THE ANGLES OF INCLINATION OF SAID BELL CRANK FOR FORWARD STITCHING, WHEREBY SAID ANGLE OF INCLINATION IS MINUTELY ADJUSTED THROUGH SAID MANUAL FEED REGULATING CAM BY ROTATING SAID KNOB WITHOUT CONNECTION TO SAID AUTOMATIC CAM THEREBY ENABLING FREELY INCREASING AND DECREASING OF THE FORWARD STITCH PITCH TO ADJUST THE PITCH OF THE FORWARD STITCHING EQUAL TO THE PITCH OF THE REVERSE STITCHING AND TO ADJUST STITCH LENGTHS OF THE FORWARD AND REVERSE STITCHING FOR AUTOMATIC BUTTON STITCHING TO EXACTLY EQUAL LENGTHS.