Moisture metering control apparatus

For use with a lithographic duplicating machine comprising a master cylinder, fountain means including a fountain roller for supplying dampening fluid to a master on the master cylinder, and a drive element:

• a control means for metering the rate of feed of the fluid, comprising:
• an actuating arm mechanically connectable with the fountain roller for rotating the same unidirectionally;
• linkage means for oscillating the actuating arm and rotating the fountain roller in intermittent increments, said linkage means comprising:
• a first link supported for swinging movement about a pivot means associated with the actuating arm;
• a second link pivotably connected with the first link and supported for swinging movement about a fixed pivot;
• an operating means forl imparting swinging movement to the first and second links as a unit about the fixed pivot in response to movement of the drive element;
• means for adjusting the linkage means with respect to its operation in a first mode including means to adjust the position of the fixed pivot to a selected normal position to set the magnitude of the incremental motions of the fountain roller to a desired value by infinitesimal degrees to control the feed of dampening fluid during a printing operation;
• and
• means for moving the fixed pivot, independently of the setting of the adjusting means, between the selected normal position as determined by the adjusting means, and a low-moisture position closer to the axis of the pivot means, providing operation of the linkage means in a second mode in which the fountain roller is rotated in increments of less magnitude than those which characterize operation in the first mode.