GB732157A - Improvements in hectographic copying machines - Google Patents

Abstract

732,157. Duplicating machines; feeding sheets. BLOCK & ANDERSON, Ltd. Feb. 23, 1954 [March 2, 1953], No. 5767/53. Classes 100 (1) and 100 (2). In a duplicating machine of the kind in which the copy sheet is fed to the printing couple by a pair of feed rollers driven at first from the initial rotation of the master cylinder from zero position and thereafter rotated idly by the tension of the sheet as it is drawn through the printing couple, means are provided whereby after the first rotation of the cylinder the drive to the feed rollers is automatically disconnected so that, when making copies of a length greater than the circumference of the master cylinder, the feed rollers are not driven when the cylinder starts its second revolution. The feed-roller driving arrangement is as described in Specification 682,842 and employs a cam 15 on the master cylinder 2, acting through a spring-loaded follower-lever 16 to oscillate a toothed quadrant (not shown) meshing with a gear having a unidirectional coupling with one of the feed rollers 13, 14. By this means the initial rotation of the cylinder 2 causes the sheet fed to the feed rollers to be advanced to the printing couple. When the follower roller 17 of lever 16 encounters the fall part of the cam 15 the drive to the feed rollers ceases and they rotate idly as the sheet continues its progress through the printing couple. When taking copies of length greater than the circumference of the cylinder 2 further rotation of the feed rollers is prevented by a latch 20 arranged to engage an arm 19 of the lever 16 and hold it the extreme (anticlockwise) position. The latch 20 is normally held inoperative by a catch lever 22 pivoted at 23 and spring loaded so that a notch thereon engages a pin on the latch. When it is desired to print long copies a finger 25 is thrown over in a clockwise direction so that a disc 26 attached thereto engages the catch 22 and releases latch 20. When the follower 17 reaches the highest point of cam 15, i.e. at the end of the drive to the feed rollers, the lever 16 is latched against movement in the opposite direction under the influence of the spring. The latch is re-set by movement of the manually operated lever 12 adapted to displace the impression roller 3 out of contact with the master cylinder during reverse rotation necessary for unwrapping the master sheet between printing operations. For this purpose there is attached to latch 20 a link 27 having a pin 28 for engagement with the rear of the lever. A spring loaded arm 6 carries a roller 7 which normally engages in a notch 5 in a disc 4 on the master cylinder to locate the cylinder at the end of each printing operation. Rotation of the finger 25 also causes the arm to be displaced to an inoperative position so that there is no locating action at the end of each rotation of the master cylinder.