the inner bearing ring 12 of the other bevel roller bearing 11 is supported on a tensioning nut 19 which may be threaded on to a thread 18 of the inner sleeve 7 as a result the two sleeves 6 7 forming the pivot bearing may be firmly tensioned relative to each other the relatively long design of the sleeves 6 7 ensures a considerable degree of stiffness against bending i e against tensile forces exerted on the two bevel gear angular drives 2 3 in the drawing plane in opposite directions the inner sleeve 7 is also hollow with a shaft 20 extending through it and with the bevel gears 22 associated with the two bevel gear angular drive 2 3 being attached to the shaft 20 two bevel roller bearings 23 23 39 provided for the bearing system are received in bearing bores 24 of the outer sleeves 6 and 25 of the inner sleeve 7 and are axially secured by securing rings 26 39 in their positions on the shaft 20 and at the respective contact faces of the two sleeves 6 7 in the region of the bearing bores 24 25 the two ends of the shaft 20 are provided with teeth 21 21.