No-play gear drive for printing machines

摘要

A no-play drive for a printing press in which a main and auxiliary driving gear are both in mesh with a driven gear. The auxiliary driving gear is mounted upon a cylindrical hub formed on the main driving gear. A plurality of axially extending bores are formed in the main driving gear and a plurality of matching conical recesses are provided in the auxiliary driving gear. Balls fitted in the respective bores have associated coil springs for pressing the balls outwardly in the direction of the recesses so that the auxiliary driving gear tends to be forcibly rocked into a detented position with respect to the main driving gear in which the matching bores and recesses are all in respective alignment. The bores and recesses are so angularly phased with respect to the gear teeth that when the auxiliary driving gear is in its detented position the teeth on the auxiliary driving gear are angularly offset by a small amount with respect to the teeth on the main driving gear with the result that the engaged teeth on the driven gear are pinched between teeth on the driving gears for removal of play between the driving and driven gears. A retaining disc secured to the hub engages the outer surface of the auxiliary driving gear to hold the latter axially captive and for the purpose of developing frictional drag for damping oscillatory movement between the main and auxiliary driving gears which tends to occur in the face of fluctuating load.