Patent GB-122007-A (GB)
Title: Improvements in or relating to Printing Presses.
IPC: B41F33/12
Filed: 1918-01-07
Abstract: 122,007. Anglo-American Inventions Syndicate, (Harris Automatic Press Co.). Jan. 7, 1918. Tripping, throw-out, and like a r r a n g e m e n t s.-In printing presses of the kind provided with devices for throwing-off and throwing-on the impression alternately in successive cycles of operation of the press, means operated automatically on failure of the sheet feed are provided to throw-off the impression in any cycle of the press and this automatic throw-out is adapted also to disconnect the drive of the feedrollers. The invention is particularly for use in presses in which slip sheets are passed unprinted through the press alternately with the sheets to be printed. As shown applied to a rotary offset press in which the offset cylinder 16 is mounted in eccentric bearings 27 by which it is moved to and from the impression cylinder 17, the bearing 27 shown is connected by link 83, bell-crank 82, and link 79 to n bell-crank 71 which is mounted on a stud 70 on the machine frame 14 and has its arm 73 connected by a link 74 to an arm 68 mounted on a stud 67. The link 83 and bellcrank 82, and the link 79 and bell-crank 71 form toggles. The arms 73, 68 have shoulders 72, 69 faced with hardened plates and adapted to be engaged alternately by the end 65 of an adjustable rod 64 carried by an arm 53 which is oscil. lated by a cam 51 on the impression cylinder shaft 21 thereby depressing the rod 64 and actuating the arms 73, 68 to throw-on and throw-off the impression. The movement of the arms 73, 68 is limited by the engagement of adjustable stops 75, 76 with a fixed stop 77. The rod 64 is moved from one shoulder 72 or 69 to the other at every cycle of operation of the press bv connexions from a cam shaft 37 which is rotated once for every two revolutions of the impression cylinder by bevel gearing driven from the shaft 21. The shaft 37 carries a cam 38 engaging between the arms 43, 44 of a lever to which is connected a link 45 provided with a U-shaped block 46, Fig. 5, adapted normally to engage a block 47 on the end of the arm 48 of a bell-crank lever, the other arm 60 of which is connected by a. link 59 to the bracket carrying the rod 64. A spring 63 tends to hold the lever 48 in its highest position. During one revolution of the impression cylinder, the cam 38 makes half a revolution and through the linkage 45, 48, 60, 59 moves the rod into engagement with the shoulder 69 so that, by the action of the cam 51, the impression is thrown off. During the next revolution of the impression cylinder, the cam 38 completes a revolution and returns the rod 64 to engagement with the shoulder 72 so that the impression is again thrown on. The impression is thrown off automatically upon failure of the feed by the following mechanism. A feeler lever 127, Fig. 13, is pivoted in a carrier 129 secured to the shaft 117, Fig. 1, of the sheet-forwarding roller 123 and is normally held by the sheet clear of the upper end of a lever 136, the other end 138 of which is formed as a latch and holds a shaft 89 against the action of a spring which tends to turn the shaft in an anti-clockwise direction. The shaft 89 is provided with an arm 91, Figs. 1, 5, carrying a rod 92 which passes freely through the block 47 and is provided with a block 94 having a bevelled part adapted to co-act with the bevelled end of the link 45. When a sheet is absent, the feeler 127 falls and engages the lever 136. and thereby releases the shaft 89 from the latch 138 so that the shaft 89 turns and raises the rod 92. The engagement of the block 94 with the end of the link 45 disconnects the block 46 from the block 47 and the block 94 engaging the block 47 raises the arm 48 and throws off the impression. When the feed is again in operation, the shaft 89 is reset by a finger 145, carried by a cam-operated arm 143, engaging an arm 148 of the shaft 89. The mechanism for throwing off the impression on failure of the feed is also adapted to disconnect a clutch 109 in the driving mechanism of the feedrcllers 87, 88 and to this end the block 94 is attached to a link 96, the lower end of which is provided with a lug 97, Fig. 7, adapted when the link 96 is raised to lift a latch 98 clear of a shaft 101 which is then turned by a spring to open the clutch 109 by a link 114 and bell-crank 113. After lifting the latch 98, the link 96 is thrown outwardly by the engagement of a lug 105 on the link with the shaft 101 thereby allowing the latch to disconnect itself from the lug 97. The shaft 101 is reset by depressing a treadle 106.