The invention refers to a device for increasing the efficiency of any rotary power generating system with progressive variation, whose planetary system may have two or more pairs of pinions, or/and satellites with any multiplication/demultiplication ratio with respect to the central pinion, characterized in that it consists of an assembled inner box, A, which is assembled axially in an assembled outer box, B, to which an assembled side box is axially fixed, C; assembled inner box, A, made of a primary drive shaft, (1), having a flange, by means of which the shaft is oriented and fixed on a cover, (2), in which, axially, is assembled a bearing, (3), and radially, in some bosses, a, processed cylindrically, are fixedly assembled some bearings, (4), in which, with a shoulder, conventionally right, son satellites, (15), are assembled, each of which, on a median shoulder, has assembled a bearing, (4); axially, in the bearing, (3), is assembled an intermediate pinion, (6), which, to the left of its toothed crown, has assembled a second bearing, (18); in some bearings, (19), (FIG. 4) which are fixed in the cover, (2), are assembled some pinions, (14), which mesh both with the pinions, (15), and with the toothed crown of the intermediate pinion, (6); on the cover, (2), and oriented on the bearings, (4), (18) and (19), is centered an intermediate cover, (5), which is firmly fixed to the cover, (2), by some screws, (13); on the cover, (5), being oriented and fixed a cylindrical wall, (20); on the conventional left side of each pinion, (15), one eccentric, (16), is fixed rigidly (FIG. 1, FIG. 4, FIG. 5, FIG. 6); after each eccentric, (16), on each pinion, (15), a bearing, (4), is assembled; on each bearing, (4), it is oriented, and on the cylindrical wall, (20), is oriented and fixed another cover, (21), in the center of which is assembled a bearing, (22), through which the intermediate pinion, (6), slides; assembled box, B, consisting of a cover, (23), oriented by means of a bearing, (24), on the primary motor shaft, (1), from the assembled inner box, A, cover, (23), on which it is oriented and fixed by means of screws, (25), with the conventionally right surface, an external cylindrical wall, (26), from which, on its conventionally left surface, a cover, (27), is oriented and fixed, by means of screws, (28); cover, (27), which is oriented by