Angular speed reduction device

An angular velocity reduction device comprising a first circular element (1) passing through the center of a fixed plate (8) and freely rotating with respect to said plate at an angular velocity W1, wherein the first element (1) is meshing with a second element (2) including at least one planet gear (20) integral with the fixed plate through an end piece (21) as a single piece with said planet gear and serving as an axis of rotation, each planet gear (20) being freely rotatable with respect to the fixed plate (8) and driven by the first element (1), the planet gears (20) being in contact with the inside of a first ring gear (4) driven by the second element (2) at the angular velocity W2, said ring gear (4) and the first element (1) being concentric, the first ring gear being made integral with a second ring gear (5) so that the first ring gear drives said second ring gear (5) at the same angular velocity W2, one of the two ring gears (4, 5) comprising a skirt (50) without teeth wherein is fitted the other ring gear (4), a third element (3) being meshing with the first element (1) and the internal portion (51) of the second ring gear (5), the center of the third element (3) being driven by the first element and the second ring gear at the angular velocity WO3 along a circular trajectory with a predetermined radius (R3) intermediate between the radius (R1) of the first element and the internal radius (R2) of the second ring gear, the third element comprising at least one planet gear (30) mounted freely rotatable in an output plate (6) through an end piece (31) as a single piece with the planet gear (30) and serving as an axis of rotation, each planet gear being freely rotatable about its axis, the third element (3) driving the output plate (6) at the angular velocity W3, the output plate further comprising at least one end piece (60) serving as an output axis, this axis and the first element (1) being concentric, the parts (1, 2, 3, 4, 5, 6, 8, 9) of the device being inserted into a guide tube (7) positioned in the flange (B) or the frame of a motor, the outside diameter of the second ring gear (5) and the diameter of the output plate (6) of the device being equal and matched with the diameter of the bore of the guide tube (7) so that there is no mechanical clearance between on the one hand the internal wall of the guide tube (7) and on the other hand the output plate (6), the third element (3) and the second ring gear (5), the guide tube (7) further comprising at its other end an annular rim designed to accommodate an attachment plate (9) positioned facing the output plate (6) and attached to the guide tube (7) via at least one screw or one pin, the attachment plate (9) comprising an opening through which protrudes the end piece (60) of the output plate (6) serving as an output axis, said end piece (60) being freely rotatable with respect to the attachment plate (9).