forming engagement part which thus forms said pivot element 16 the engagement part 18 is provided with an elongate through running groove 20 for receiving the upstream end part of the vane 14 and engagement dowels 21 arranged in the vane 14 for securing the vane 14 and the connection bar 17 to each other seen in the machine direction the groove 20 is provided with inner support walls 22 for the engagement dowels 21 the dovetail engagement groove 11 of the anchoring element 10 and circular pivot element 16 of the connection bar 17 form parts of said mounting arrangement in accordance with the present invention the mounting arrangement further comprises a special assembly bar 23 extending along the anchoring element 10 at its upstream end the assembly bar 23 is designed with a continuous protrusion 24 having the same dovetail shape as the engagement groove 11 of the anchoring element 10 to be received in the same with good lateral fit i e without play and to be brought into locking wedge co operation with the engagement groove 11 with good fit i e without play between the assembly bar and the anchoring element so that the assembly bar 23 is secured to the anchoring element 10 by forming a tight joint resistant to torsion further the assembly bar 23 has a continuous journaling groove 25 that extends through the.