Patent GB-458278-A (GB)
Title: Improvements in or relating to railway or like signalling systems
IPC: B61L1/16
Filed: 1935-09-11
Abstract: 458,278. Railway signalling systems. STANDARD TELEPHONES & CABLES, Ltd., and BROWN, A., 63, Aldwych, London. Sept. 11, 1935, No. 25244. [Class 105] A railway signalling system in which the signals are controlled by the counting-in and counting-out of axles as a train enters and leaves a section is provided with means whereby if a signal has been left at danger by incorrect counting in and a train then proceeds, under the usual stop and proceed at caution rule, into such section and effects a correct counting- in and counting-out the signal is returned to the clear aspect. The counting apparatus is automatically or manually reset after any incorrect operation but the signal does not clear until the counting apparatus has been correctly operated by a train or, in a modification, by two trains. The counting is effected by treadle-de-energized relays TRA, TRB the back contacts tra2, trb2 of which energize the stepping magnets RMA, RMB for a counting switch-device IC which towards the end of the counting-out picks up a guard stick relay GR and at the completion of a correct counting-out energizes a line relay LR. The signal clears over series front contacts of the two relays GR, LR. In normal operation the entry of a train opens a front contact tra1 to de-energize the guard stick relay GR and thus the signal goes to danger; when the train leaves the section the guard relay GR is picked up by the switch device IC shortly before the completion of the counting- out and when the counting-out is correctly completed the line relay LR is energized over a front contact gr2. During the counting-out operation a slow relay TQ is energized over back contacts trb2, tqx4. A front contact tq2 of such relay energizes a high resistance winding of a relay TH. On the cessation of the counting and after an interval the slow relay TQ drops and this at back contact tq3 causes a lamp L to be energized in series with a low-resistance winding of the relay TH. The increasing resistance of the energized lamp L in due time causes the relay TH to drop. This delay device TH does not exercise any control when correct counting takes place, but if the counting is defective, then a back contact lr2 will still be closed when the device TH is energized and later de-energized and the action of contact th2 of the device TH is first to energize a slow relay TQC and then to pick and stick a relay TQX over contacts tqc1 tqx1 respectively. A front contact tqx5 in conjunction with the back contact lr2 then energizes a relay HR to close its front contact hr1 whereby the stepping magnet RMB is energized. The interrupter contacts rmb which at this time lie in the circuit of the relay HR cause the relay HR and stepping magnet RMB to vibrate until the counting switch CI takes up the zero position. When the zero position is reached the line relay LR is energized over a front contact tqx7 and by opening its back contact lr2 drops the relay TQX so that the apparatus comes to rest. It should be noted that the opening of a back contact tqx3 during the re-setting causes the stick relay GR to drop and thus the signal will remain at danger. If a train now proceeds through the section and the apparatus operates correctly, then the relay GR will be picked up and the relay LR will be energized and thus the signal, will go to clear. A caution signal may be given by a stick relay AR which is picked up over a front contact tqx6. Thus a train may not enter until the apparatus has been re-set. For manual resetting, Fig. 2 (not shown), the relay TQX is directly energized by a push.