positions which are marked in the drawing these two positions correspond to the two positions u201c upper shed u201d or u201c lower shed u201d of the heddles 4 and consequently the shedding of the warp threads 2 however the position of the abovementioned elements is not free but is prestressed by a spiral tension and compression spring 8 such that in the two end positions u201c upper shed u201d and u201c lower shed u201d a spring force directed away from the stops takes effect while in a middle position of the coils 6 no spring force takes effect two stop magnets 26 are arranged such that they form holding means for the two end positions u201c upper shed u201d and u201c lower shed u201d the graph 3 shows the force conditions of the elements described above in this case the spring force graph 100 shows that the spring force of the spiral tension and compression spring 8 is symmetrical about the middle position in which it disappears and is linear during a raising or lowering movement of the heddles 4 the largest fraction of energy is applied by the spring drive of the spiral tension and compression spring 8 however the movement is initiated by an electric motor 32 as long as the electric motor 32 is not in operation the corresponding heddle 4 is retained by the upper or the lower stop magnet 26 in the upper or lower end position which correspond to the upper shed position or the lower shed position of.