an inking unit for use in a rotary printing machine is disclosed . a plurality of endless belts are placed side by side along the surface of a driving roller . these belts transport a liquid medium such as printing ink or damping fluid along the surface of a covering of a cylinder in the direction of the longitudinal axis of the cylinder . the liquid medium is transported by the belts from a position of excess ink to a position of less ink thereby ensuring a uniform distribution of the liquid along the surface of the roller .