bottom end of the feeder rod 8a an end of a connecting plate 31 is connected to the intermediate height position of the carrying pin 17 whereas the other end of this connecting plate 31 is connected to the top end of a cam plate 22 which is to be described later on which presses the feeder rod 8a downward by virtue of the arrangement of those components described above the cam plate 22 swings itself back and forth by way of pivoting on a swing movement supporting pin 21 in relation to the vertical movement of the carrying pin 17 as shown in fig3 the bottom end domain of the cam plate 22 is substantially of a 34 twin hill 34 cam shape which accommodates a pair of cams 23 available for pressing down a slide roller 24 at the tip end of the feeder rod 8a at such intervals substantially being equal to the width of the coupling recess 14 next operation of the drive unit 9 available for driving yarn feeders 8 is described below first drive signal output from a control unit not shown activates operation of a carriage drive unit to move the carriages 5 on the upper surface of needle beds 3 as a result these carriages 5 are permitted to properly adjust forward and backward movement of those knitting needles 4 mounted on respective needle beds 3 while these carriages 5 still keep on operating a bistable solenoid 15 is activated by a control signal available for pattern knitting in such a region where no knit is composed then as shown in fig3 output shaft 16 of the bistable solenoid 15 enters into a set position in such a state in.