A motorization device comprises two substantially parallel winding cylinders, and at least one longitudinal linking element able to maintain a predetermined distance between the winding cylinders and wound around winding tracks, the linking element consequently having a crossing point located between the winding cylinders. The motorization device includes two flexible tracks, fixed on each of the winding cylinders and arranged to face and to touch eachother at the contact point, a pre-stressing force being applied to the contact point under the effect of said linking element. The flexible tracks are spiral shaped and arranged such that the contact point between the two spiral-shaped flexible tracks, located between the winding cylinders, is offset relative to the crossing point of the linking element, such that a torque dependent on the distance between the contact point and the crossing point is applied to the contact point, causing reciprocal rotation of the flexible tracks.