Device for conveying ink or a damping agent

In a fluid supply system for a printing press, the combination comprising a frame, a fountain including a fountain roller journalled in the frame and driven at slow speed so that a film of fluid is formed on its surface, a distributor roller journalled in said frame parallel to the fountain roller and spaced therefrom to form a gap, a ductor roller movable broadwise through a short distance in the gap, a pair of arms for supporting the ends of the ductor roller, a shaft journalled in the frame for rigidly supporting the arms, a driving arm rigidly secured to the shaft, a thrust rod having one end pivotally connected to the driving arm and the other end carrying a cam follower, a rotary cam and means for driving said cam means directly connected to both said frame and said thrust rod for maintaining the cam follower in contact with the cam so that upon rotation of the cam the shaft oscillates to swing the ductor roller back and forth for successive engagement of the fountain roller and the distributor roller resulting in conveyance of fluid therebetween, means defining opposed way surfaces at the ends of the arms oriented generally perpendicularly to the plane of the arms, mounting blocks at the ends of the ductor roller snugly slidable on the way surfaces, the cam having sufficient throw to produce relative overtravel of the cam follower, and paired springs on the respectively opposite sides of each of the mounting blocks and working in opposition to one another to define a normal position of the ductor roller with respect to the arms on which it is mounted and so that upon engagement of the rollers the relative overtravel is yieldingly accommodated by the deformation of the springs.