Ink fountain drive mechanism

In an ink fountain of the type having a rotatively mounted fountain roller, a roller drive mechanism comprising:

• A. a wrap spring overrunning clutch having an input drum, an output drum, a concentric sleeve encircling both drums, and a coil spring grippingly encircling the drums within the sleeve, said spring having its end adjacent the input drum secured to the sleeve,
• B. means for connecting the roller for rotation with the output drum,
• C. means for oscillating the clutch input drum through a selected angle, the oscillating input drum movement in one direction causing tightening of said spring about the input and output drums right at the start of each oscillation whereby the clutch output drum and sleeve, as well as the fountain roller are rotated in said direction commencing right at the start of each oscillation,
• D. means for positively stopping the rotation of the clutch sleeve after the sleeve has rotated through a desired stroke angle so as to loosen the spring windup and thereby decouple the input and output drums and thereby terminate the angular advance of the output drum and the fountain roller in said direction before said input drum completes its rotation through said selected angle,
• E. means for adjusting the stopping means so as to alter the point at which the stopping means stops the clutch sleeve thereby to change the angle through which the fountain roller is rotated during each oscillation of the clutch input drum, and
• F. means for calibrating the adjusting means to the stroke angle of the fountain roller, wherein the calibrating means includes means on the sleeve and input drum which engage one another to prevent relative rotation of the clutch input drum and the clutch sleeve in the driving direction when the clutch input drum is positioned at the beginning of its driving stroke.