Patent GB-674332-A (GB)
Title: Improvements in or relating to apparatus for automatically controlling electrically driven tandem and sequence conveyors, and other inter-related moving mechanisms
Inventor: NORDMANN LEONARD ARCHER
IPC: B65G23/00
Filed: 1949-06-29
Abstract: 674,332. Endless conveyers. WOOD & CO.. Ltd., H. June 23. 1950. [June 29, 1949] No. 17198/49. Class 78 (i) [Also in Group XXXVII] In the control of inter-related moving mechanisms such as electrically driven tandem and sequence conveyers, a generator is driven mechanically from the master mechanism of the series and the output fron this generator operates relays controlling the electric driving motors of the slave mechanisms so that when the speed of the master mechanism varies the relays operate to stop or start the driving motors of the slave mechanisms. A master conveyer MC, Fig. 5 is fed by a slave conveyer SC which is driven by a motor 24. The motor 24 is controlled by units A and B through a relay operated switch C, each unit A or B consisting of a generator 3 or 27 respectively, adapted to be driven by the band of convever MC or SC respectively and a number of relays. The field winding 3a, Fig. 4, of generator 3 or 27 has a rheostat 8 in series with it. By this means the voltage of the generator can be set to a constant value indicated by the meter 15, this constant value being adjustable to suit conveyers of different operating speeds. When the master conveyer driving motor is switched on the operation of the control devices is in the following sequence starting from the initial condition as shown. Relay 16 closes immediately-the purpose of this relay being to cut off the motor 24 immediately upon the master conveyer slowing down. Delay relay 19 then closes so as to complete a circuit through relay 22 which operates the starting switch 23 of motor 24, and shortly afterwards delay relay 21 closes which in. turn energizes relay 17 which both inserts a lock-out resistance 25 and also connects relay 17 directly across the generator. Thus if the circuit through relay 22 is broken and re-made the current through resistance 25 will not be sufficient for operation. The remaining relay 20 of box A which is normallv closed has a further delay of twenty seconds during which the generator 27 of box B is run up to speed by the slave conveyer. This causes a relay 26 to close before relay 20 opens. If relay 20 opened first due to faulty starting of the slave conveyer relay 19'would be cut out and so cut out relay 22 and switch off motor 24. Similarly the subsequent cutting out of relay 26 by a falling off in speed of the slave conveyer would switch off motor 24. Upon slowing down of the master conveyer all relays return to the initial position. A switch 29 bypasses the relays in box A and by its operation the slave conveyer can be operated independent, ly of the master conveyer. For detecting slip between the driving roller and the belt of either of the conveyers two further generators D, E Fig. 6, are provided, one driven by the belt and one by gear transmission from the driving shaft. Each passes a current through one coil of an opposed pair forming a differential relay 28. When slip occurs the relay breaks the circuit through relay 22 and thus switches off the motor 24.