Patent GB-889419-A (GB)
Title: Improvements in or relating to conveyors
Inventor: VALE LINDSAY HAROLD
IPC: B61B10/02
Filed: 1957-05-17
Abstract: 889,419. Conveyer systems. ELECTRIC & MUSICAL INDUSTRIES Ltd. May 15, 1958 [May 17, 1957], No. 15773/57. Class 104 (2). In a conveyer comprising an indexing section in which articles can be stocked and a service section which can initiate release of an article in the indexing section and its movement to a position of transfer to the service section and wherein the sections have different article-moving chains, the speed of chain in the service section being adjustable, means are provided for controlling the time of release of the articles in the indexing section in response to the speed of the article-moving chain of. the service section. In an overhead chain-drive type of conveyer shown, the chain 1 propels trolleys 3, 4, 5 along a track 7 in an indexing section by means of dogs 8, 9, 10, 11, and a chain 2 provided with dogs 26a, 26c, 27, drives a trolley 6 along the track 7 of a service section. In the indexing section the driving dogs, such as shown at 9a, can be lifted out of driving engagement with abutments, such as 13 on the trolley 4, by levers such as 14, 15, 16, 17, which can be raised by electromagnets, such as 18, 19, 20, 21 which are controlled by switches 22, 23, 24, 25 operated by ramps such as 26, on a passing trolley 3. Switch 25, on closure by ramp 26, energizes and raises the electromagnet 21 and the switches 24, 23, 22, on closure, raise the electromagnets 20, 19, 18 respectively, provided the preceding electromagnet is closed. The dogs 26a, 26c, 27 provided on the service section chain 2 are not retractable but are arranged to take over the drive when a trolley, such as trolley 6, reaches a transfer position A. Two limit switches 28, 29 are provided to control the release of trolleys from the indexing position and their movement to the transfer section A. The switch 29 is located in such a position that when the chain 2 is moving at its maximum speed the time taken for the dog to travel from the position of engagement with the switch 29 slightly exceeds the time taken for the chain 1 to transfer a trolley from the indexing position to the transfer position A. The spacing of the switch 28 from the switch 29 is the same as the spacing from the switch 29 to the transfer position A. When switch 28 is closed by a dog 26a a relay 30 is energized to condition a counter 31 to count pulses 33 having a repetition frequency related to the speed of chain 1 and applied by way of a lead 32. If the chain is travelling at maximum speed a predetermined number n of the pulses will occur during the passage of the dog 26a from the switch 28 to the switch 29 and of the dog 26c from the switch 29 to the transfer position A. The counter 31 comprises two sections 34 and 35 of which the section 34 has a capacity of n pulses whilst the section 35 has a capacity of (m-n) pulses where m is the maximum number of pulses which may be counted during the passage of the dog from the switch 28 to the switch 29 with the chain 2 travelling at its slowest speed. The count registered in section 35, when the switch is reached by the particular dog which has initiated the counting, corresponds to the delay required before releasing a trolley 5 from the foremost index position, in order that the trolley may arrive at the transfer position A at the right time to be driven without delay by the corresponding dog on the chain 2. The switch 29 is closed, when reached by the dog in question, to de-energize relay 30 and to energize a relay 36, The pulses 33 are thus prevented from reaching the counter 31 but are transferred to a counter 37 which is so arranged that when it registers the same count as section 35 is completes a circuit to the switch 25 and electromagnet 21 to release lever 17 and the next dog 10 on chain 1 propels the trolley 5 to the transfer position A. When the counter 37 and section 35 reach the same count the relay 36 and counters 31 and 37 are reset to place the apparatus ready for operation by the next dog on the chain 2. The counters 34, 35, 37 may be uniselectors. The switches 22, 23, 24, 25, 28, 29 may be replaced by photoelectric devices. The apparatus may be used for a chain conveyer or other types of positively driven conveyers.