that winding of yarn 34 a 34 is interrupted and yarn 34 a 34 comes to a standstill within knotting or splicing apparatus 22 for a short instant subsequently second control unit 13 supplies a start pulse to apparatus 22 resulting in the now stationary yarns 34 a 34 and 34 b 34 being joined by knotting or splicing at station 22 39 as soon as this step is finished which is accomplished in a short instant of time device 20b is moved further downward by engagement of second control pin 35 with control surface 36 into the position shown in fig7 b since in this position stop surface 25 39 is in engagement with first stationary stop 29 downward movement of device 20 causes central plate 24 to be shifted relative to clamping blade 28 whereby the hitherto clamped end of yarn b is released at the instant at which yarn b is released yarn clamping and cutting device 20a for yarn a is in the position shown in fig7 a due to prior counterclockwise rotation of plate 32 whereupon line 20a is shifted upwards by engagement of a control edge 39 with control plate 32 in this position stop surface 26 39 is in engagement with second stationary stop 30 whereby upward movement of device 20a results in central plate 24 being shifted relative to cutting blade 25 and clamping blade 28 so that the yarn end 34 a 34 extending towards the knotting or splicing point is cut while the yarn end extending in the opposite direction is clamped and retained as a result yarn a is now in a position corresponding to that.