Multiple ribbon mandril for multiple print head printers

In medium to high volume printers using more than one print head, multiple documents may be printed side by side in one pass. Multiple rolls of ribbon are utilized on the ribbon mandril to accommodate the documents. The ribbon is kept taut across its print head by the feed system controller. When the outside diameters of the two rolls of ribbon vary, the system keeps one ribbon taut and the other tends to go slack at the print head. A split sleeve mandril with a differential mechanism connecting the two sleeves of the mandril assures that both ribbons are maintained taut. The preferred differential mechanism may be a planetary gear arrangement, or a thrust bearing arrangement. A unique ribbon roll holding mechanism, to hold the ribbon roll at the selected place on the mandril is also provided.