GB748773A - Improvements in or relating to sheet feeding mechanism for rotary printing machines - Google Patents

Abstract

748,773. Printing-machines; feeding sheets. TIMSONS, Ltd., and TIMSON, E. A. April 22, 1954 [April 30, 1953], No. 11971/53. Classes 100 (1) and 100 (2). Tripping-arrangements; faulty sheet-feed control devices.-In a rotary offset machine including offset, impression, and printing cylinders 1, 2 and 3, respectively, wherein the offset cylinder 1 is adapted to be lifted away from the other cylinders when a sheet is not fed to the cylinder 2, sheets are advanced over a feed board 4 up to oscillating stops, and are then transferred to grippers 7 on the cylinder 2 by a series of grippers 6. The grippers 6 may be mounted on oscillating levers or, as shown, on spaced discs 8 secured to a shaft 9 rotated stepby-step by a Geneva mechanism. Each gripper 6 comprises a movable jaw 10 which co-operates with a fixed jaw 12 on the disc, the faces of the jaws constituting pairs of electric contacts included in the circuit of a solenoid 13. Thus the faces are separated when they grip a sheet on the board 4, but if a sheet is absent they make contact and complete the circuit to cause the solenoid 13 to be energized. When this occurs, an armature 13a, and a link 24 connected thereto, is drawn downwardly to rock a bell-crank 23 which pulls links 21 to the left and breaks toggles 20 interposed between the links 21 and vertically slidable bearings 15 of the offset cylinder 1. The bearings 15 are now urged upwardly by one end of an arm 11 pivoted at 17, the other end of the arm being urged downwardly by a tension spring 18 secured to a screw 19. The bearings, toggles and levers are restored to the original position automatically by a cam 28, secured to the cylinder 1, engaging a roller 27 on the bell-crank 23. Specification 454,295 is referred to.