thread and seam warp threads is particularly critical in the first three seam warp threads in order to bring the seam weft thread into engagement with the first three seam warp threads the pressure in the bearing pressure cylinders 32 is approximately doubled when the engagement with the first three seam warp threads is created the pressure is reduced to the normal value thus approximately halved the sley 10 remains stationary during the period of time necessary for the pressure reduction this period of time is e g approximately 50 ms simultaneously the stress applied by the draw through gripper is also reduced from the draw through stress to the hold or roll in stress while the outermost right hand reed dents 22 press the seam weft thread into the seam warp threads the sley 10 moves on the chosen pressure in the bearing pressure cylinders 32 is such that the pressure strip 30 is pressed rearward by the reed dents 22 which have reached the fell i e pivoted clockwise in the chosen example the reed dents 22 act progressively from right to left on the seam weft thread to be shifted with the result that finally this is completely pressed against the fell and engages with the seam warp threads generally the next seam weft thread to be shifted is a warp.