Abstract: The speed reducer comprises a first shaft which is supported so as to be able to slide axially, is suitable for being rotatingly actuated and a pinion whose set of teeth are slightly beveled is located thereon. A second shaft is supported so as to be able to slide axially with an axis parallel to the first shaft and a gear and a further pinion, are located thereon both having sets of teeth slightly beveled in opposite directions and suitable for meshing respectively with the pinion of the first shaft and with a further gear which is fixedly located on an output shaft, coaxial to the first shaft. A device is provided for adjusting the axial position of the first shaft, so as to move the sides of the conical sets of teeth of the gears closer in order to eliminate the related clearances.

Abstract: A reduction unit includes a sun gear (2) which is integral with the driving shaft (1), and is equipped at the two ends of the shaft with two identical toothings (3, 4) which mesh with three free planetary gears (7) which in turn mesh with the fixed (10) and rotary (11) internal ring gears; between these ring gears there is a difference of three teeth.

Abstract: In the speed reducer disclosed, the gear ring (12) of the planetary gear train is connected via a pair of diametrically-opposed appendages (13) with a corresponding pair of vertically disposed and parallel double-acting hydraulic cylinders (14) suspended via ball-and-socket joints beween the gear unit and a fixed structure. Each cylinder shows a low pressure (31) and a high pressure (32) oil chamber connected to low and high pressure hydraulic accumulators (33, 34) respectively by means of respective throttle valves (35, 36) in parallel with respective ball check valves (37, 38). There are no bearings between the gear case (18, 19)and the shaft instead, the output shaft hub is fitted with an assembly which incorporates thrust rings and a rotary seal (20) featuring diametrial-flow lubrication to ensure freedom from foreign matter.