present in fig1 to move the said units 14 16 15 17 in the x direction on the arch frame 3 in this embodiment the drive motor 21 is connected to the drive shaft unnumbered of the reversing roller 46 fig2 and 3 illustrate the precise position matching of the sewing head 15 and of the shuttle box 17 by showing the press foot 22 fig2 and the needle clamp 23 fig3 with the needle unnumbered on one hand and the shuttle 24 fig2 on the other the sewing heads 14 and 15 and the shuttle boxes 16 and 17 are guided on two guide bars 25 26 and 27 28 respectively of the respective crossbeams 6 and 7 of the arch frame 3 these guide bars 25 through 28 are linked by supports 29 fig3 to the crossbeams 6 7 and contribute to the accurate guidance and positioning of sewing heads 14 15 and shuttle boxes 16 17 the connection between the guide bars 29 and the sewing heads 14 15 as well as the shuttle boxes 16 17 is implemented by slide pads 30 shown in fig3 the sewing heads 14 15 and the shuttle boxes 16 17 can be linked by a coupling to a segment or portion 31 and 32 respectively of the endless belts 18 and 19 as shown in fig2 and 3 the coupling consists of disengaging and re engaging means including a coupling member 35 which by means of an actuator 34 can be vertically displaced on a.