CONVEYOR MECHANISM

Overlapping signatures are transported between upper and lower belts, wherein the upper belt passes around three pulleys, the first of which is supported at the free end of a vertically swingable first arm extending generally horizontally from its pivot. The second pulley is carried on a second, vertically swingable arm. Springs pull downwardly on the free end of the second arm to tension the belts. The third pulley is journaled on the pivot axis of the second arm. The belts pass over the third pulley, under the second and over the first. The line of pull of the belts extends from the top of the second pulley to the top of the first pulley at an angle to the horizontal such that a downward component of force is exerted on the first pulley, urging it downwardly against the signatures. The first pulley rises and falls with the first arm to accommodate variations in thickness of the line of signatures. The second pulley rises and falls approximately the same distance as the first to accommodate the length of the upper belt to the increased bulk of bunched-up signatures traveling on the conveyor, while maintaining the same angle of pull on the first pulley, with respect to the horizontal, so that the downward component of force remains the same.