Shift-over device for controlling the turning drum grippers of a rotary sheet printing press

摘要

A shift-over device for controlling the turning drum grippers of a rotary sheet printing press optionally changeable for one-side printing or two-side printing and having a relatively rotatable gripper opening cam and an axially movable gripper turning cam includes a rotatable switching shaft carrying a stop arm with adjustable stops mounted on the press frame for engaging the stop arm and limiting the rotation of the switching shaft in opposite directions. A first crank arm is secured to the switching shaft and carries a lash lever coupled to the gripper opening cam for relatively rotating it incident to oscillations of the switching shaft. A second crank arm is secured to the switching shaft and coupled to a push arm having face cams engageable with push rods connected to the gripper turning cam for axially shifting it incident to oscillations of the switching shaft. In the preferred embodiment, a pneumatic cylinder is connected to a drive crank secured to the switching shaft and a source of pneumatic pressure with a control valve interposed between the source and the pneumatic cylinder is provided for actuating the cylinder to oscillate the switching shaft and simultaneously rotate the gripper opening cam and axially shift the gripper turning cam.