Patent GB-717492-A (GB)
Title: Improvements in hectographic copying machines
Inventor: BROWN ROLAND
IPC: B41L11/00
Filed: 1950-08-31
Abstract: 717,492. Operating clutches; reverse gear. BLOCK & ANDERSON, Ltd. Aug. 24, 1951 [Aug. 31, 1950; May 31, 1951], Nos. 21557/50 and 12841/51. Class 80 (2) [Also in Group XVI] A duplicating machine comprises a cylinder carrying a fixed clip adapted to secure a mask or a printing master and a movable clip lying lengthwise of the cylinder and traversable lengthwise thereof when the cylinder is at rest, and a combined pressure roller and clamping unit capable of traversing lengthwise of the cylinder independently of the movable clip to register with and print from any desired zone of the fixed master. Figs. 3 and 6 show the machine in plan and section. The printing cylinder 8 is carried on bearings 9, 10 through which passes a screwed rod 11 controlling the position of the movable clip 16 longitudinally of the cylinder. The carriage 30, on which is mounted the pressure roller, is traversed by a screw 31. The printing cylinder is driven from a motor 90, Fig. 2, through pulleys 100, 101, 102, 103 and spur gears 104, 105, the latter being connected to the cylinder shaft 9 for one or more revolutions as required. This is effected by a ratchet 106 fast with the gear wheel 105 which is freely mounted on the cylinder shaft, and a co-operating pawl 107 pivoted on a cam 121 on the cylinder shaft. The pawl is normally retained out of engagement with the ratchet by a bellcrank lever 108 the end of which is supported in de-clutching position by a pivoted latch 110 which is displaced by a Bowden wire control to allow the pawl to engage the ratchet wheel. The Bowden wire is connected to a manually operable press bar 114, Figs. 1, 3. Before the end of a complete revolution of the cylinder the cam 121 engages a roller 120 on the lever 108 which rocks to disengage the pawl. A spring-loaded cam follower 123 then snaps into a notch in a cam wheel on the cylinder shaft to retain it in the rest position. It is also retained by a hook 126 engaging a pin 127. The traverse screws are driven in opposite directions for displacement in one direction or the other by drives from the shaft 150, Fig. 1, which carries a pulley 151 connected by a belt to pulleys 152, 153 on the screwed rods 31 and 11 respectively. Geared to rotate in the direction opposite to pulley 151 is a pulley 156 connected to other pulleys on the screwed rods 31, 11. Either pulley on each rod may be connected to the rod by a clutch so that the clip or carriage is traversed in one direction or the other. Each clutch comprises a driven member 160, Fig. 13, a driving member 161 keyed to the end 13 on the screw rod 11 and a pawl 164 mounted in a housing 163 and spring loaded into engagement with teeth 172, 173 on member 160 and tooth 171, on member 161. The pawl has a tooth 167 arranged to engage either of teeth 172, 173 and a tooth 169 to engage tooth 171. Fig. 10 shows controlling means for the clutch which comprise an arm 180 adapted to be placed in the path of a projecting tooth 165 on the pawl 164 to lift it out of driving connection with the teeth 171, 172 and 173. The arm 180 is carried on a plate 186 biased to declutching position by spring 188. A spring-loaded arm 181 engages in a notch 183 in the clutch housing to lock it and the rod 11 against backward rotation when the clutch is decoupled. Pins 189, 190 project from the plate 186. A control link 191 pivoted at 192 to an arm 193 is notched to engage pin 190 so that when arm 193 is moved clockwise by a Bowden wire control 199. plate 186 and arm 180 are swung clockwise and the clutch is coupled. The plate is retained in this coupling position by a hook 205 engaging pin 189. Hook 205 is released to allow declutching by a lever 195 having a pin 196 bearing under the link 191 and actuable by a Bowden wire 197 connected to a limit stop at the end of the traverse for the carriage. The clutch governing movement in the opposite direction is provided with two control devices, one of which provides for continuous engagement of the clutch to give any whole number of revolutions and the other of which includes a clutch throw-out device positively actuated within the first revolution of the driven shaft to allow only one revolution of the shaft at a time causing step-wise displacement. The first device comprises a hooked lever engaging a pin on plate 186 and holding it in coupling position as long as a push-button control for this lever is held down. The second device consists of a control link as 191 and a cam on the driven shaft which engages a lever connected to lift the control link to allow the plate 186 and the arm to move to uncoupling position. Both the lever and the link are moved to release the plate 186 at the end of the traverse. To adjust the clip 16 or carriage 30 to any traverse position it may be moved to the end of its traverse in one direction and then moved step by step ' in the reverse direction. The devices controlling the clutches for the traverse of the clip and carriage 30 are coupled together for dual or individual operation so that by one operation of a common control member for two clutches simultaneous drive of both the clip and the carriage may be effected and by individual operation of the respective clutch controls either the clip or carriage may be separately driven. The control members are manually operable push-buttons 250, Fig. 1, which are locked against operation when the cylinder has been set in motion by actuation of press-bar 114, by an apertured masking plate 287, Fig. 1, which is caused to slide under the heads of the buttons. Similarly, depression of the buttons prevents actuation of the press-bar 114 to set the cylinder in motion so that the cylinder cannot be driven simultaneously with the clip or carriage. A cam 64 turning with the cylinder restores the masking plate towards the end of each complete revolution.