edge 62 see fig5 and 6 the cloth strip side slider 80 is connected with a pneumatically operatable displacing module 84 by means of a supporting bar 83 this pneumatically operatable displacing module 84 is movable between two end positions in which the lower arm 82 of the cloth strip side slider 80 either engages under the bearing plate 61 as shown in fig5 and 6 or in which both are free from one another i e have been moved apart in the x direction further a trouser side slider 85 is provided at the bearing plate 68 which slider 85 is slidable between an inner and an outer end position equally by means of a displacing module 86 a supporting bar 87 extending further than the cloth strip side slider 80 is secured to the displacing module 86 the trouser side slider 85 consisting of a flat and substantially rectangular plate is secured to the supporting bar 87 in a vertically slidable manner by means of two vertical guide rods 88 pre tensioned helical coil compression springs 89 which surround the guide rods 88 and by means of which power is exercised in downwards direction on the side slider 85 are provided between the supporting bar 87 and the side slider 85.