GB847416A - Improvements in or relating to rotary duplicating machines - Google Patents

Abstract

847,416. Feeding sheets to rotary duplicators. RITZERFELD, W., and RITZERFELD, G. Feb. 7, 1958 [March 8, 1957], No. 4048/58. Classes 100(1) and 100(2) In a rotary duplicating machine wherein the printing drum is arranged to be coupled to a continuously rotatable driving means, the coupling means cannot be operated if a sheet to be printed is fed with its leading edge in incorrect alignment, or if no sheet has been fed. As shown, the drum 11 is secured to a shaft 4 on which is rotatably mounted a chain-driven ratchet-wheel 1, and the drum is rotated when a release lever 5, pivoted at 6, releases a pawl 9 on the drum so that it can be urged by a spring 10 into engagement with the rotating ratchetwheel, the pawl being lifted by the lever 5 after one complete revolution of the drum. An L- shaped lever 18 is pivoted at 19 to the upper end of a pedal or hand lever 7, and to one end of a lever 17 pivoted at 16. A knuckle spring tends to urge the lever 18 clockwise so that it engages one end of a lever 21 pivoted at 22. The other end of the lever 21 is connected to the spring loaded plunger of a solenoid 20. In the energised position of the solenoid plunger, when the operating pedal 7 is depressed to initiate a printing operation, the lower end of the lever 18 cannot engage an abutment 23 on the release lever 5, and the pawl 9 is not released. When the solenoid 20 is de-energised, the lever 18 can move clockwise so that its lower arm is in alignment with the abutment 23: depression of the operating pedal 7 now causes the release lever 5 to be rocked, against the action of a spring 13, about its pivot 6 to release the pawl 9, and the printing drum 11 is driven for one revolution. The de-energisation of the solenoid 20 is caused when the front edge of a correctly registered sheet depresses two electric contacts 28, 28a which are spaced apart transversely of the machine. These contacts are mounted at 29 and their upper ends lie in circumferential grooves in an insulated feed roller 26 and are urged resiliently against a co-operating roller 27 which is electrically conductive. The roller 27 is in circuit with the solenoid 20, and the two contacts 28, 28a are arranged in parallel so that both contacts must be engaged by the front edge of a sheet to cause the solenoid to be deenergised. As described, A.C. is supplied to a transformer connected to a full-wave rectifier which supplies D.C. to the solenoid circuit.