Intaglio printing press systems for recto-verso intaglio-printing of sheets for the production of banknotes and like securities

An intaglio printing press system for recto-verso printing of sheets for the production of banknotes and securities, wherein the intaglio printing press system comprises first and second intaglio printing units each comprising an impression cylinder cooperating with a plate cylinder carrying at least one intaglio printing plate which is inked by an inking system and wiped by a wiping system, said first and second intaglio printing units being operatively-coupled to one another directly by a sheet transporting system located between the first and second intaglio printing units and comprising a single chain conveyor system, with the exclusion of any additional chain conveyor system located between the first and second intaglio printing units, which single chain conveyor system includes spaced-apart gripper bars for transporting the sheets from the first intaglio printing unit where recto printing is performed to the second intaglio printing unit where verso printing is performed, said first and second intaglio printing units being disposed in a mirrored configuration such that said impression cylinder and said plate cylinder of the first intaglio printing unit rotate in directions opposite to the directions of said impression cylinder and said plate cylinder of the second intaglio printing unit;

• wherein the sheets are taken away from the impression cylinder of the first intaglio printing unit by said chain conveyor system and wherein said sheet transporting system further comprises a transfer drum or cylinder placed between the impression cylinder of the second intaglio printing unit and a downstream end of the chain conveyor system for transferring the sheets from the chain conveyor system directly to the impression cylinder of the second intaglio printing unit.