Patent GB-754341-A (GB)
Title: Improvements in rotary hectographic copying machines
Inventor: BROWN ROLAND
IPC: B41L11/08
Filed: 1954-02-12
Abstract: 754,341. Duplicating-machines. BLOCK & ANDERSON, Ltd. Feb. 10, 1955 [Feb. 12, 1954; April 26, 1954], Nos. 4240/54 and 12030/54. Class 100 (2). In a rotary duplicating- machine of the kind having a clip for securing the master sheet to the printing cylinder, means for adjusting the pressure applied by the impression cylinder and clutch means for driving the printing cylinder in one direction, two control devices are provided for the clutch which allow the printing cylinder to be stopped in two positions, in one of which the master sheet is in correct register for printing and in the other of which the clip is in position to receive a new master sheet, the clutch control devices being so inter-connected with the printing-pressure control means that the printing pressure must be taken off before the printing cylinder can be brought into the master insertion position. The impression cylinder 2 is swingably mounted on levers 32 for pressure engagement with the printing cylinder 1. Pressure is applied by a lever 35 pivoted at 36 having a pin 38 co-operating with a retaining quadrant 37. A roller 39 at the lower end of the lever 35 acts to displace a lever 40 pivoted at 41 and connected to an arm 42 bearing down on a bail 34 straddling the cylinder mounting levers 32. When the lever 35 is pulled backwards (anti-clockwise as shown) the printing pressure is applied. Sheets are fed over a table 4 and are forwarded by driven rollers 5, 6, the upper one of which is moistened. The printing cylinder 1 carries a pawl 14 pivoted at 15 and spring-loaded into engagement with a constantly rotating ratchetwheel 13 driven for instance from an electric motor. The drive is interrupted by stop devices 29 and 50 which can be moved into the path of a lug projecting from the pawl 14 and cause the pawl to swing out of engagement with the ratchet and bring the printing cylinder to rest. The stop device 29 is carried on a bellcrank lever 28 pivoted at 23 and loaded by spring 24 into the operative position. It is kept out of the path of the pawl by a lever 25, mounted on a shaft 26, which engages a roller 27 on the bell-crank lever. The other stop device comprises a hooked lever 50 pivoted at 51 on a resiliently mounted lever 52. A link 58 from lever 50 has a pin-and-slot connection with lever 25 so that one stop is rendered inoperative when the other stop is moved into operative position, only one of these stops being allowed to be operative at once. In another form (not shown) the lever 50 is directly connected by a link 65 to the lever 35 so that when the lever is displaced to apply printing pressure the stop device 50 is rendered inoperative, thereby allowing the printing cylinder to rotate through a small angle from the position B to the position A. In position B the master clip 9 is disposed immediately adjacent the lower end of a feed tray 17, 18 for the master sheet. In position A, determined by the stop 29, the master sheet is registered with incoming copy sheets. The printing cylinder may then be driven for printing by displacement of lever 25, e.g. by a foot pedal. In the form illustrated however, the printing cylinder is allowed to rotate through more than one complete revolution in moving from position B to position A. For this purpose the link 65 is connected to the lever 35 by means of a pivoted quadrant 61 loaded by spring 63 to bear by pin 68 on the lever 35. A pin 66 on link 65 is engaged in a right-angle slot 67, and lies in the horizontal or vertical part of the slot according to the position of a lever 70 having a limb 72 adapted to lift the link 65 when desired. An arm (not shown) on shaft 26 has a pin cooperating with a latch which is released once in each revolution of the printing cylinder, e.g. by connection with a pump operating cam thereon. This latch serves to retard the movement to operative position of stop 29. The pin 66 is normally in the vertical part of slot 67 and the lever 70 in the pressure-off position as shown in Fig. 3a. When the lever 70 is displaced the pin rises in the slot 67 and can then move to the left in the horizontal part. This allows the stop 50 to swing out of engagement with the clutch pawl and the printing cylinder begins to rotate. The lever 25 is prevented from moving into the position shown in Fig. 2 by the cam-operated latch which is released during the first revolution so that the stop 29 can move into position and stop the printing cylinder in position A ready for printing. The impression cylinder is not inked during this first revolution because until the lever 35 is pulled there is no printing pressure. When the lever 35 is displaced to apply the impression cylinder the pin 66 returns to the vertical part of the slot 67 so that the clutch control devices are again governed by the lever 35. A hook 30, Fig. 2, co-operates with a pair of notches 20, 21 in the driving disc of the printing cylinder to prevent the cylinder moving backwards after being stopped in either of positions A or B. As shown in Fig. 5, the clip 9 is opened by an operating lever 106 which acts through levers 110, 111, 112 to move the clip bar outwards radially. The operating lever is locked by a spring-loaded catch 101 pivoted to the machine frame at 102 and having an abutment 104 co-operating with a pin 105 on the end of the operating lever. The catch has a nose 109 which co-operates with a pin 108 on the driving-plate of the printing cylinder so that in the position B the catch is.released and the clip-opening lever 106 may be actuated. In all other positions the clip-opening lever is locked.