GB191200246A - An Improved Lithographic Printing Press. - Google Patents

Abstract

246. Read, J. W. Jan. 3. [Cognate Application, 17,998/12.] Cylinder machines; stopping, starting, and tripping arrangements; gripper mechanism; offset machines.-A printing-machine of the kind described in Specification 23,804/08 is constructed so as to be driven by power, the cylinder being arranged so as to be capable of being both tripped and untripped automatically for each reciprocation of its carriage. A pivoted feed-table is used which is normally lowered by cam mechanism, but which may be tripped by a hand mechanism which may also trip the cylinder for inking-up &c. An improved gripper mechanism is provided, and the delivery apparatus is attached to the frame of the impression carriage, and its tapes are driven from the fixed rack by an arrangement of ratchet-wheels and pawls which cause the delivery tapes to move continuously in the same direction. As shown in Figs. 1 and 2, the impression carriage c which also carries the inking and damping rollers, is reciprocated by a sprocket-chain d fitted with a stud d<3> working in a slot c<2> in a depending arm c<3> of the carriage, which is fitted with cushioning-plungers g<1> coacting with dashpot cylinders g. The impression cylinder is mounted as described in the Specification referred to above, but the hand-operated lever, which was operated to throw the impression cylinder into operation at the feed end of the press, is replaced by a lever n, Fig. 2, operated by a stop o mounted on a pivot o<1> and capable of being set by a crank o<2> so as to prevent the roller from being brought into action when desired, for instance when the bed is being inked-up. The chain d is driven from a shaft f, Fig. 3, which is fitted with a clutch comprising driven parts f<1>, f<2> freely mounted on the shaft f, and an expanding part fixed to the shaft f and operated by depressing a freelymounted treadle h, which together with an integral arm h' and sliding sleeve h<2> are moved axially along the shaft f by a fixed cam-surface and a cam-surface h<3> on the sleeve h. The sliding motion of sleeve h<2> causes the clutch to be expanded owing to an adjustable connexion between the two, and so the shaft f remains in action until the treadle h is returned to normal position. The grippers s, Fig. 4, of the impression cylinder are preferably operated by a lever s<2> and a pivoted cam-member formed with two operating-surfaces t<2>, t<3>, which are alternately brought into action to open and close the grippers at the feed and delivery positions. The cam is pivoted to a fixed boss m<1>, about which the cylinder m oscillates. The machine may be used to give offset impressions by fitting a prepared blanket on the cylinder m and feeding a sheet with a protective cover to this cylinder and obtaining the offset impression as the cylinder runs over the bed. The bed-adjusting device consists of two or more parts, each part comprising a double wedge actuated by a hand-operated screw engaging a nut on the wedge.