grooves 5 2 which are rigidly connected to the housing of rotating drive mechanism 1 positioning component 5 is positioned on at least two sides of coupling component 3 grooves 5 2 have helical sections 5 21 and 5 22 at the bottom each of which merges at the top into an axially parallel section 5 23 as shown in fig2 c threaded spindle 2 is in the vicinity of its upper end rigidly connected to a collar 12 that when the in principle axially displaceable threaded spindle 2 is at its lower limiting position rests against an axial needle bearing 14 in the upper face cap 1 3 of the housing at the bottom of collar 12 is a threaded cap 13 the bottom surface of threaded cap 13 constitutes a stop for the upper terminal surface 3 1 of coupling component 3 takeoff shaft stub 2 1 is connected to rotating post 25 in such a way that they can neither rotate nor move up and down in relation to each other by means of a connector 15 with reference now to fig2 a and 2b collar 12 has an axial groove 12 2 at its upper edge 12 1 and there is a supporting plate.