The invention relates to improvements in the object of patent P200603269 for “Automatic rotation system for tilting seats of chairs or armchairs”, comprising rotation supports formed by two parts (1 and 2) which are rotating in relation to one another, between which there is incorporated a rotating draw-spring (4), one of the parts (2) of each rotating support determining an annular channel (5), in which there is housed a ring (6) together with a high-viscosity silicone filler, such that said ring (6) is linked by pulling with the other part (1) of the rotating support, a braking action occurring on the rotation movement between the two parts (1 and 2) due to the friction of that ring (6) with the silicone in the channel (5).