Patent GB-731683-A (GB)
Title: Improvements in and relating to hectographic copying machines
IPC: B41L9/10
Filed: 1952-06-11
Abstract: 731,683. Duplicating machines. BLOCK & ANDERSON, Ltd. (Veenman's Kantoorinstallatie-Bureau). Sept. 11, 1953 [June 11, 1952], No. 14708/52. Class 100 (2). A rotary hectographic duplicating machine having a clip for holding a master sheet movable axially of the drum by means of a leadscrew coaxial with the drum also comprises automatic means controllable by the operator whereby when it is desired to move the master clip one step after a copying operation, the lead-screw is held against rotation relatively to the drum and energy is stored in an energy storing device during that copying operation so that by releasing the lead-screw immediately before the completion of the rotation of the drum, it is rotated by the energy storing device thereby imparting a corresponding movement to the movable master clip. A slight dwell in the surface of the printing cylinder coincides with the impression cylinder in the initial position so that no printing pressure is applied. The lead-screw 1, Fig. 1, is arranged for manual operation by a handle 37 on shaft 52 adapted to be coupled to shaft 49 connected to the lead-screw by bevel gears 47, 48. Axial movement of the shaft 52 causes coupling or uncoupling. For the automatic actuation of the lead-screw it also carries a pinion 19 adapted to mesh with a sliding rack 16 movable on a guide member 12 hinged at one end 14 to a fixed bracket and having a spring-loaded sliding latch member 21 at the other end adapted to engage a portion 23 thereof behind a fixed projection 24 to hold the guide in such a position that the rack is in engagement with the pinion 19. Also mounted for rotation with the lead-screw is a control plate 29, Fig. 3, having a recess 30 in the periphery. A spring-loaded lever 28 rotating with the printing drum carries a roller 27 engaging in the recess and normally retains the lead-screw in a zero position corresponding to predetermined fixed steps of the master clip. Surrounding the plate 29 is a fixed ring 25 having a cut-away part 26 arranged to allow the roller 27 to be cammed out of the recess 30 and allow the lead-screw to make a revolution relative to the printing cylinder. This can only occur near the initial position of the printing drum. The guide 12 is connected by a link 11 to a lever 3 pivoted at 4 and connected by a link 2 and a safety spring (not shown) to a foot pedal. When this pedal is depressed the guide 12 latches in operative position so that the rack 16 engages with the pinion 19. Rotation of the printing cylinder then causes the rack to be displaced along the guide against the action of spring 17 in which energy is stored. Relative rotation of the lead-screw is prevented by the roller 27 engaged in the recess in plate 29, the roller being constrained by the ring 25 as soon as the printing cylinder leaves the initial position. When the printing cylinder again approaches the initial position the roller 27 is freed and the rack spring 17 causes the leadscrew to make one complete revolution as it returns the rack to the normal position. The latch 21 is tripped by the return movement of the rack so that the guide moves to inoperative position disengaging the rack if the foot pedal is released, the link 2 being restored by a spring 9. On actuation of the foot pedal a pivotal camshaped catch 5 on the free end of lever 3 causes longitudinal displacement of a slider 8a by engagement with a pin 8 on the downward stroke. This slider 8a serves to connect the clutch controlling the printing cylinder and starts the printing operation. The clutch may otherwise be connected by a separate pedal acting through link 33 and bell crank lever 51, when it is not desired to move the master clip at the end of the printing operation. Actuation of both pedals at once is prevented by a rocker 34 pivoted at 32 and engaging pins 35, 36 on the respective links 2, 33. Forward movement of shaft 52 to couple the handle for manual control causes a lug 38 to engage the portion 23 of the latch 21 and release the guide so that the rack is disengaged from the pinion. The link 2 is locked against actuation by the foot pedal when the printing cylinder is not in the initial position. This is effected by a cam-controlled hooked arm (not shown) engaging a lever con. nected with the clutch operating slider 8a. Specification 717,492 is referred to.