GB901871A - Improvements in or relating to printing machines - Google Patents

Abstract

901,871. Printing-machines. LINOTYPE & MACHINERY Ltd. Aug. 24, 1959 [Sept. 8, 1958], No. 28729/58. Class 100 (2). A printing press has hydraulic jacks operable to bring the impression cylinder to an impression position for a printing operation, the hydraulic jacks being actuated by hydraulic fluid under pressure from a pump, the supply of hydraulic fluid being under the control of a valve operated in timed relation with the printing press, whereby fluid under pressure will be delivered periodically to the hydraulic jacks to bring the impression cylinder to an impression position at the appropriate time in the printing press cycle. As applied to a tworevolution cylinder machine, the impression cylinder 1 is supported in bearings 3 slidable in guides 4. The bearings 3 are secured to rods 6 which carry springs 7 urging the cylinder into an impression " off " position. Rams 19 of hydraulic jacks 10 engage blocks 8 adjustably secured to the rods 6 by nuts 9. The jacks 10 are supplied with oil from a pump 11. Hydraulic pressure and thereby the loading of the rams 19 is controlled by a relief valve 13. A control valve 14, which may be as described in Specification 874,309, is operated in timed sequence with the machine. Closure of the valve 14 causes downward movement of the rams 19 to move the cylinder 1 into impression " on " position. The rams 19 are hydraulically cushioned during the end portion of their upward stroke by the return flow of oil through an adjustable needle valve 20 which by-passes a non-return valve 21. The load on the impression cylinder is indicated by a pressure gauge 22.