by a tie rod 25 which is pivotally supported at its two ends 23 and 24 the actuating arm 26 is rigidly connected with a first double arm lever 27 28 and swingable with the latter around a shaft 29 an initial tension is constantly exerted on the lever arm 27 by a first spring 30 the one end of which rests against a fixed part of the frame 1 a brake 31 is operatively associated with the pile warp beam 5 this brake is fastened at its one end to a fixed part of the frame 1 while its other end is held to the one arm 32 of a second double armed lever 32 33 the double armed lever 32 33 is swingable about a shaft 34 while its other arm 33 is continuously under the pressure of a second spring 35 whose other end rests against a fixed part of the frame 1 on the lever arm 33 there is mounted a bar 36 which bears a stop 37 at its free end the arm 28 of the first double armed lever 27 28 is displaceably guided on the bar 36 at its end which faces away from the swivel shaft 29 and it can slide back and forth between the stop 37 and the arm 33 of the second double armed lever 32 33 when the loom is in operation pile warp yarns 10 are continuously required for the weaving process these yarns are pulled off from the pile warp beam 5 by.