Abstract: A drive unit for distribution systems for materials of fluid behavior, such as livestock feed materials, in which a cable provided with spaced-apart conveying elements is caused to slide inside a tube, said drive unit being of the type comprising a geared motor, on the output shaft of which there is fixed a toothed wheel about which the cable winds. The geared motor is mounted on a supporting structure in a freely oscillating manner such that as the tension in the slack branch of the cable varies, the position of the axis of the toothed wheel varies by virtue of its rotation about an axis passing essentially through the point of tangency between the toothed wheel and the taut branch of the cable.