end of arm 42 is connected to the right needle rod 12 via an intermediate linkage 43 the switching means for the drive mechanism 10 comprises two stop plates 44 and 45 which are swingably mounted on a bearing pin 46 fixed in the machine housing and are connected with the link pins 29 and 36 in the articulation of the respective articulated linkage pairs 26 27 and 33 34 via respective connecting rods 47 and 48 which act as guiding link rods two simple air cylinders 49 and 50 serve to swing the stop plates 44 and 45 the piston rods 51 and 52 of the respective cylinders 49 and 50 are pivotally connected to respective arms 55 and 56 of the respective stop plates 44 and 45 in order to kinematically define the operative and inoperative positions for the needle rods 11 and 12 the stop plates 44 and 45 each have two stop surfaces 57 58 and 59 60 respectively which interact with detents not shown on the interior of the machine housing as shown in fig3 the pneumatic cylinders 49 and 50 are controlled via pneumatic valves 64 and 65 connected to the cylinders by flexible tubing 66 and 67 additional features of the drive mechanism 10 for the two needle rods 11 and 12 are described in u s pat no 4 569 297 rotary hook not shown and a material feed dog 69 fig2 cooperate with the needles 11 and 12 the feed dog 69 is attached to a support 71 which is accommomated under the stitch plate 70 fig4 of the sewing machine the support 71 is connected to a forked crank 73 attached to a rotationally oscillating shaft 74 rotatably mounted in the machine housing for driving shaft.