Gripper control for sheet-fed rotary printing presses

Claim 1

Gripper control means for sheet-fed printing presses, comprising a shaft on which an impression cylinder is mounted, oscillatably mounted gripper means for feeding sheets to the printing press, a cam mounted on said shaft, actuating means operatively connected between said cam and said gripper means to oscillate said gripper means by said cam and said actuating means upon rotation of said shaft, spring means connected to said actuating means to apply a spring force to the oscillating motion of said gripper means, and control means connected to said spring for controlling said spring force, said control means being connected to said shaft, wherein said gripper means includes a hollow shaft, said acutating means including a lever arrangement operable by said cam for oscillating said hollow shaft, and said spring means comprises a torsion spring extending in said hollow shaft, a bearing shaft member oscillatably mounted in said hollow shaft, said torsion spring having one end thereof attached to said bearing shaft member, said control means including a mechanical connection between said bearing shaft member and said impression cylinder shaft, said mechanical connection comprising a crank mounted on said shaft, a chain attached to said crank, an eccentric cam mounted on said bearing shaft member, said chain being attached to said cam at the curved segment of the latter closest to the axis of symmetry of said bearing shaft member, said chain being arranged on said cam in such a manner that the chain is wound on and off of said eccentric cam for each oscillation of said bearing shaft.