Patent GB-362444-A (GB)
Title: Improvements in electrical signalling apparatus
IPC: B61L25/04
Filed: 1930-08-23
Abstract: 362,444. Electric signalling systems. RELAY AUTOMATIC TELEPHONE CO., Ltd., Relay House, Streatham Hill, London, BRITISH POWER RAILWAY SIGNAL CO., Ltd., Windsor Works, Slough, Buckinghamshire, and MORDIN, R., Relay House, Streatham Hill, London. Aug. 23, 1930, No. 25238. [Class 40 (i).] In a train describing system comprising receivers at two or more locations for storing and causing the display, in sequential order of receipt, of train descriptions, arrangements are provided whereby a description at one or more, but not all, of the locations is removed irrespective of the positions it occupies in the describers. The invention is particularly applicable to two describers associated with a junction and two main arrangements are described. In the first, Fig. 1, two describers at B, C are both required to display descriptions of all trains passing over a main line ML and a branch line NM. A branch line description is removed from both describers as soon as the train passes treadle TRx while a main line description is removed from B C in succession as the train passes over treadles TRx, TRy respectively, associated with track sections x, y. As a branch train may operate TRx before a preceding main line train has operated TRy and as in such a case, the branch description would be the second description at C, arrangements are provided to cancel this description at C simultaneously with the first description at B. The describers may in conjunctipn with the treadles, also be controlled by the position of the points. In the second system, Fig. 7, the describer, e.g. a platform indicator, at B displays only branch descriptions, while that at a cabin C displays both main and branch descriptions so that the description to be removed at C by a train passing treadle TDx on the branch line is not necessarily the first on the display panel. A re-transmitter may be provided at either or both describers. Setting of a describer, say C, Figs. 1, 3 and 4. Impulses from a distant cabin over C1 operate a receiver RC, for example as described in Specifications 321,415, 321,426, [both in Class 40 (i), Electric signalling systems &c.], and assuming that the describer at C is blank, ground connected to one of the dotted wires on the left of Fig. 3 operates a relay, say Q3, which locks to 202 and operates Z3 which energizes Q2, Z2 since Y3 has been operated from receiver RC. Relay Z2 releases Q3 and Z3 so that Y2 pulls up. Similarly Ql, Z1, Yl are operated and Q2, Z2, Y2 are released. Q1 lights lamp CQ1 to illuminate a train description. Similarly, the next two incoming descriptions light a lamp CQ2 .. CT2 and CQ3 .. CT3. The upper two of each series of lamps show main line trains, and the lower two branch lines for which relays SX1, TX1 .. SX3, TX3 also pull up in series with the lamps. The describer, Fig. 2, at cabin B is similar and is operated over the same wire C1, but only the describer for the first train is shown. Cancellation of descriptions. It will be assumed that, initially, at both cabins the first description is a main line train and that the second description is a branch line train. The first train, on entering track x, releases track relay TR, Fig. 5, which releases TRX1, TRX2 in turn. Relay TRX2 is slow so that a ground pulse over 2, 3, M operates CB1, CB2, Fig. 2, in turn, which on cessation of the pulse, release ZB and the operated describing relay QB or RB and the second-description at B moves up to replace the cancelled description. These operations are without effect at cabin C, but when the train enters track y, the corresponding track relay grounds wire Ml, Fig. 4, to operate CL1 which releases Z1, Q1 or R1 and the second description is transferred to the first indicator. A branch line train is now shown on the first indication in both cabins so that SB or TB, Fig. 2, and S1, SX1, or T1, TX1, Fig. 4, are operated. When the train enters track section x, the first description at B is removed as before, but, in addition, CB1 connects a ground pulse over 4 or 5 5 to BC1 (S or T) to operate CL1 (128 is connected to battery). CL1 opens the holding circuit HC but maintains SX1 or TX1 operated during the ground pulse to prevent the pulse operating CL2 in the second indicator if a branch line train (SX2 or TX2 operated) were shown thereon. If the branch train enters x before the previous main train had entered y (main train on first indicator at C) the description on the second indicator would be deleted by the ground pulse on BC1 since SXI, TX1 would not be operated. Modified cancellation arrangements controlled by position of points. Relays similar to SX1, TX1 are also provided in conjunction with the main line lamps CQ1, CR1, &c. in Figs. 3 and 4, and the sets of four relays control circuits of four conductors corresponding to BC1 and adapted to be connected to the lamp circuits as in Fig. 6, which shows a portion of Fig. 2 modified for this purpose. When the points are set for the main line, SG2, Fig. 6, is operated, SG1 being operated when the points are set for the branch line. When a train enters x with the points set for main line, the ground pulse on M operates CB3 which opens the holding circuit HB for the first indicator at B but has no effect on C. Thus if the points are set for the main line, the description at C remains even if the train entering x is a branch train. If the points are set for branch, the ground pulse operates CB1, CB2 in turn, HB is opened to cancel the first description at B and CB1 connects a ground pulse to one of the BC1 wires to bring about the cancellation of the first description at C as previously described. Modified system, Figs. 7 and 9, for a branch train platform indicator at B and signal cabin C. The indicator at B shows only branch trains, while the descriptions of all trains are required at C, this being done under the control of a single receiver R provided with means, described later, for discriminating between the two classes of trains. Assuming a branch train shown in the first positions at B and C and a main train in the second position at C, the branch train on passing into section TDx grounds wire S, Fig. 9, relay CL1 opens the holding circuit H of indicator B with results as previously described in connection with results as previously described in connection with HB, Fig. 2, and operates CL2 to connect ground over one of the contacts n2 (branch trains showing) to relay C1 which opens the holding circuit so that the branch train description is replaced by the main train description. The main train arriving at TDy grounds TC (full line) which operates Cl to delete the main train description. If the main train arrived at TDy before the branch train description had been deleted, the grounding of TC would have been extended over back contacts of Ml or M2 and front contacts of similar relays in position 2 to C2 which cancels the main train description in the second position. The indicator at B may be provided for are-transmitter T as described in Specifications 321,415, 321,426 and 339,308, [all in Class 40 (i), Electric signalling systems &c.], for sending on to the next branch station a description deleted from the first position at B. If main and branch trains are shown in the first and second positions respectively at C and a branch train arrives at TDx before the main train arrives at TDy, the operation of CL1, CL2 as previously described connects ground over back contacts n2, position 1, and front contacts n2 position 2, to operate C2 which removes the second description. The means whereby receiver R discriminates between branch and main line trains is shown in Fig. 8. When the receiver is operated, one of relays M81, M82 pulls up if the train is a main one and one of B81, B82 if the train is a branch. The marking ground on MW is extended over the operated relay to one of MW1 .. BW2 and thence to the lamp operating relays in the third position, Fig. 9. If B81 or B82 is operated BX1 and BX2 also pull up in turn and the marking ground is extended over bw1 or bw2 to the last position in the describer at B. Re-transmitting arrangements. If the describer at C, for example, is to re-transmit, the dotted line circuits are added to Fig. 9 and removal of a description is delayed until re-transmission has taken place. The main line relay Ml or M2 in addition to displaying the description, marks a wire mk1 or mk2 leading to re-transmitter RT, and the ground signal signifying passage of a train is now connected to TC (dotted) and starts the re-transmitter which may be of the kind described in the previously mentioned Specifications. When transmission is complete, the transmitter grounds TC(x) to operate C1 or C2 to remove the first description at C if that is a main line description or from the earliest position in which a main line description is displayed, RT being marked from the second position if the first description is a branch one. If the describer at B is to re-transmit it is arranged that the branch train removal signal is not given to. C until transmission is complete.