GB937539A - Sheet feeders for printing presses - Google Patents

Abstract

937,539. Feeding sheets. LINOTYPE & MACHINERY Ltd. March 8, 1962 [March 9, 1961], No. 8686/61. Class 100 (1). A swing feed gripper system for a printing press includes overriding means to maintain the swing feed grippers open at sheet take point if a misplaced sheet or no sheet is fed to the grippers, which grippers are mounted on a gripper shaft adapted to be rocked to effect opening and closing of the swing grippers by means of a cam follower riding over a main cam surface, means being provided whereby the motion imparted by the main cam to close the grippers at sheet point is resiliently taken up as lost motion when the swing grippers are held open by the overriding means. Brackets 28 secured to a rocker shaft 30 carry two cross-bars 23, 25, the crossbar 23 being rockable and carrying gripper fingers 21 for gripping sheets against abutment pads 24 on the cross-bar 25. An adjustable sheet registration plate may be incorporated with one or more of the abutment pads, as described in Specification 769,113. One end of the cross-bar 23 is secured to a bracket 39 and is a rotatable fit in a bore in a second bracket 36. The brackets 36, 39 have co-operating platforms 49, 47 and abutment surfaces 48, 46, respectively. A compression spring 50 encircling a guide-pin 53, fixed to the platform 49 and passing through an aperture in the platform 47, maintains the abutment surfaces in engagement during normal sheet feeding. A roller 20 mounted on an arm 44 secured to a shaft 41 projecting from the bracket 36, follows a cam surface to open and close the grippers. The other end of the crossbar 23 carries an arm 34 supporting a roller 18. Operation of a solenoid 16 due to faulty sheet feed, rotates a cam 17 into the path of the roller 18, whereby the cross-bar 23 is rotated to open the grippers and maintain them open against the action of roller 20. The overriding movement imparted by the cam 17 is taken up as lostmotion by the two platforms 47, 49 moving towards each other against the action of the spring 50. Faulty sheet feed detectors.-The front edge of a feed board 1, Fig. 1 (not shown), is provided with at least one feeler comprising a pivoted L-shaped member 2. The latter is rocked by a sheet during normal sheet feed, to disengage the lower arm of the member 2 from a pendulum oscillating in synchronism with the sheet feed. The pendulum is oscillated by means of a solenoid, energized each time a sheet is fed. A microswitch 15 is closed each time the pendulum makes a full movement. If a sheet is misplaced or if no sheet is fed, the member 2 is unmoved and the pendulum remains latched. Consequently, the microswitch 15 is not closed whereby the solenoid 16 is energized to rotate the cam 17 and open the grippers.