Abstract: A ribbon feed mechanism for the inked ribbon of a printing machine comprises two ribbon-carrying spools rotatably supported in a removable cartridge and two sensing levers which extend through a pair of apertures in the cartridge to sense the amount of inked ribbon on the spools. The sensing elements cooperate with corresponding latches for retaining a reversal member against the action of a reversal spring which biases the reversal member from a first position to a second position. The reversal member supports two freely rotatable pinions which are moved by the reversal member, as it moves into the first and second positions, into mesh respectively with corresponding spool gears coupled to the two spools and with two gears driven by a feed element in opposite directions. The spools are therefore alternately driven first in one direction and then the other direction respectively.