Patent GB-696790-A (GB)
Title: Improvements in or relating to automatic switch control systems for classification yards
IPC: B61L17/02
Filed: 1951-07-27
Abstract: 696,790. Operating railway points. GENERAL RAILWAY SIGNAL CO. July 27, 1951. [Aug. 15, 1950] No. 17868/51. Class 104 (i). A switch control system in which the track switches in a marshalling yard are automatically  positioned in accordance with the route selected by manually operable devices on a central control panel and comprising a plurality of route description storage banks of relays including a storage bank associated with each of the track switches in the track layout, circuit means which act in response to the designation of a given destination for a cut of cars by the manually operable devices to condition the storage banks associated with the first track switch in the route to such destination in accordance with the position required by that track switch and all other track switches for that route, and transfer means for each storage bank except the one for the last track switch in each group, is arranged so that the transfer means for the storage bank is rendered active by the passage of a cut of cars over the track switch associated therewith to transfer the route description then existing in the storage bank and relating to the remainder of the route to the next track switch in the route; the transfer means only being effective when the associated track switch assumes the position called for by the route description stored in the associated storage bank. In the hump marshalling yard arrangement shown in Fig. 6 the track switches are arranged at four locations A, B, C and D and the switch 8W is located after the hump. The track switches are numbered so as to bear the number of the track to which a cut of cars will be directed if the track switch so numbered is in its reverse position and all the other track switches in the system are in their normal positions. The system is controlled from a central panel P1 Fig. 1 (not shown) located near the hump and has a number of self restoring push buttons PB, one for each track in the system, cancel push buttons 8CNB and CNB and indicator lamps 8SK1, 8SK2 and 8SK3. A control panel Fig. 2 is also provided for manual or automatic operation of the system and has switch levers SML for manually moving the various track switches to the reverse R or normal N positions or allowing the automatic A operation of the track switches. The levers SML are spring biased and when pulled upwards effect cancellation of the track switch operation. The system control apparatus, Fig. 10 has route storage units S associated with the control of the various track switches, and each unit has a bank of code storage relays CS, one for each track switch, through which a cut of cars may pass to its destination. The first three units 8S1, 8S2 and 8S3 each have four storage relays CS since this is the maximum of track switches through which a cut of cars will pass in the system shown, and they are fed by wires a8, b, c and d which govern the positions of the switches at the A, B, C and D locations respectively. General mode of operation. Assuming a cut of cars is to be routed to track I, Figs. 6 and 10,  a button 1 on panel P1 is pressed to set up a route description in the storage unit 8S3 calling for the operation of switches in locations A, B, and D and if the storage units 8S2 and 8S1 are not occupied the description is transferred through the wires a8, b, c and d to unit 8S1. Since switches in location C are not used in this instance wire c is not energized and only the wires of those switches to be moved to their normal position in the locations A, Band D will be energized. Once the route description has been stored in unit 8S1 switch 8W is energized to be moved or held in its normal position through wire a8. When a cut of cars occupies a track detector section of switch 8W the route description effecting the switches in locations Band D is transferred from the unit 8S1 to the storage unit 3-5S2 or if not already occupied, unit 3-5S1 through wires b3 and d2-4-6 and since wire b3 is energized the track switch 3W is either moved to or held in its normal position. The route description effecting the switches in location D is transferred when the cut of cars enters a track detector section of switches 3W and 5W, through wire 2d to transfer the balance of the route description from unit 3-5S1 to storage unit 2S2 or, 2S1 if not already occupied, to move to or hold in the normal position a track switch 2W. The route storage in unit 2S1 is cancelled when the cut of cars passes the track detector section of switch 2W. Route description. The push button 1PB Fig. 3A on being depressed to send a cut of cars to track 1 closes a back contact 23 to pick up a repeater relay 1PBR. Relay 1PBR on picking up establishes a stick circuit through a front contact 38 and energizes a relay PBP which opens a contact 22 to de-energize a bus-bar PU thus preventing the selection of a second route acting upon the condition set up by button 1PB until the route selected is transferred to the next storage unit, and to close front contacts 39, 40, 41 to apply energy through wires a8, b and c to effect storage of the route in unit 8S3. The route description is now transferred from unit 8S3 to unit 8S2 by the closing of a front contact 44 of a relay PBP to pick up relay 8TN2 which opens a back contact 21 of the bus-bar PU and push button repeater relay PBR circuits and closes a front contact 48 to establish a circuit for a description storage relay 8SD2 associated with storage unit SS2, and a stick circuit through a front contact 47 of relay 8TN2 which ensures that the route description cannot be transferred from unit 8S3 to unit 8S2 until the push button is restored to its normal position. The relay 8SD2 on being picked up opens a back contact 45 in the pick up circuit of relay STN2 and closes a front contact 54 in a stick circuit of the relay 8SD2 subsequent to the opening of a front contact 48 of relay 8TN2. The relay 8SD3 associated with the storage unit SS3 is normally energized through back contacts 55, and 56 of relays 8SD2 and 8TN2 and upon these relays being picked up relay 8SD3 is released but owing to its slow drop-away characteristics it remains up long enough to allow the storage relays CS2 of the storage unit to become energized in accordance with the energy passed through wires a8, b, c, and d. The picking up of the relay 8SD2 effects the picking up of relays 8ACS2, SBCS2 and SDCS2, which are maintained up by stick circuits through front contacts 69, 70, 71 and 73, so that the route description stored in unit 8S2 is dependent upon relay 8SD2 being held up. Relay 8SD3 on being dropped disconnects the wires a8, b, c and d from the storage relays CS2 of the unit 8S2 by opening front contacts 57, 61, 74 and 65, and opens a front contact 25 in the stick circuit of the relay 1PBR and drops relay PBP which in turn drops relay 8TN2 by opening the front contact 44 assuming the push button to have been restored to its original position. When relay STN2 drops away front contacts 59, 63, 75 and 67 are opened to further isolate relays CS2 from unit 8S2 and a back contact 56 is closed to restore relay 8SD3 to its normal position so that the route description transfer from unit 8S3 to unit SS2 is now complete. Back contact 77 is closed when relay 8TN2 drops to pick up relay 8TN1 to initiate the transfer of the route description from unit 8S2 to unit SS1. Relay 8TN1 on being picked up opens a back contact 50 in the stick circuit for relay SSD2 which relay is still held through its back contact 81 until the transfer of the route description from unit SS2 to unit 8S1 is completed, and closes a front contact 84 to pick up a description storage relay 8SD1 which relay opens a back contact 79 in the circuit to relay STN1 which is maintained up by its stick circuit through front contact 80 until relay 8SD2 drops. The relay 8SD1 on being picked up opens a back contact 83 to drop relay 8SD2 which is slow in dropping to allow the transfer of the route description from relays CS2 of unit 8S2 to unit 8S1 and thus the relays 8ACS1, 8BCS1 and 8DCS1 are picked up and so long as relay 8SD1 remains up these latter relays are held up by stick circuits through a front contact 102. On completion of the transfer of the route description from unit 8S2 to unit 8S1 relay 8SD2 drops to open front contact 73 to restore the relays CS2 of unit 8S2 to their normal position and to open a front contact 76 to drop relay 8TN1 which opens front contacts 95, 98, 103 and 101 in the pick up circuits for relays CS1 of unit 8S1 and closes a back contact 104 to energize a switch control relay 8NW or 8RW according to the position of relay 8ACS1 associated with the control of switch 8W. If the relay 8ACS1 is up relay 8NW is picked up and switch 8W is moved to its normal position and if relay 8ACS1 is down relay 8RW is picked up to move switch 8W to its reverse position. The entrance of a cut of cars in the detector track section of switch 8W drops a track relay STR to initiate the transfer of the route description (less that associated with switch 8W) to the storage unit 3-5S2. When relay 8TR is dropped back contacts 113 and 126 are closed to energize relays 3-5TN2 and SDP the latter relay 8DP being held up by a stick circuit through a front contact 127 and back contacts 125 and 126 so that as long as there is storage of a route in unit 8S1 the relay remains up. The relay 3-5TN2 on being picked up closes a front contact 128 to pick up a transfer repeater relay 8TNP which is maintained up as long as the detector track section of switch 8W is occupied and as long as relay SDP is held up to close its stick circuit through the front contact 131. The relay 8TNP on being picked up opens back contacts 116 and 125 in the pick up circuits of the transfer relay 3-5TN2 and the relay 8DP but both of these relays are held by stick circuits, the stick circuit for relay 3-5TN2 being through front contact 135 and for relay 8DP as previously described