Patent GB-583216-A (GB)
Title: Improvements relating to remote control systems particularly for railway traffic control
IPC: B61L7/08
Filed: 1942-10-30
Abstract: 583,216. Railway-traffic control systems. TOMLINSON, A. V. (Union Switch & Signal Co.). Oct. 30, 1942, No. 15267. [Class 105] In a railway-traffic control system of the kind in which control is effected from a central office and the condition of the controlled devices is indicated in the office by impulse codes transmitted over line wires extending from the office through the stations at which the devices are located, and with the objects, inter alia, of reducing the necessary number of relays and allowing a pair of line wires to be used for control and indication together with other communication facilities such as a despatcher's telephone equipment, the line wires Y, Z are arranged to be used in parallel and with a common ground return circuit as a control channel, and in series as a message or indicator channel. Figs. 1A, 1B together show central office equipment, Fig. 2 shows typical fieldstation apparatus and Fig. 3 a schematic diagram of typical line circuits. Fig. 3 shows the line wires Y, Z extending from the C.T.C. office at the left to despatcher's office at the right, the telephone channel extending from telephone apparatus 5 at the despatcher's office to similar apparatus 5 at the other end of the line. Two of a number of intermediate stations (Nos. 1, 2) are also shown, telephone equipment being indicated at station No. 1. High pass filters 6 are inserted between telephone and line, and balanced low pass filters 12 between office or station apparatus and line. The control circuit extends from earth at the C.T.C. office over contacts of transmitter relays T1, T2 through line battery 80 to one terminal of each of two balancing resistors 8, their other terminals being connected through office filter 12 across the line wires. When relay T1 or T2 is picked up; positive or negative current, respectively, flows from battery 80 over the line wires in parallel and over the station paths in multiple to earth and back to battery 80. Each station path comprises balanced connections through a filter 12, resistors 9 and the windings of relays R3, R1, R2. Relay R3 is of high resistance compared with the line resistance and is of the stick-polar type as described, for example, in Specification 498,855, [Group XXXVII]. Its armature normally occupies the left-hand position and is non-responsive to current from battery 80 as this flows in opposite directions through the two windings of the relay. Relays R1, R2 are high-resistance polar relays with armatures biased by springs and occupying the right-hand position when the relays are de-energized or energized by positive current, and the left-hand position with negative current. To transmit code impulses relays T1, T2 are energized alternately or repeatedly one at a time and operate relays R1, R2 at each station, each code comprising a station selecting group of impulses, followed by a group for effecting the desired operation at the selected station. The message line channel extends from battery 81 over back contact 31 of a line relay F, pole-changer contacts of relay T3, the right-hand side of office filter 12, line 7, then through paths in multiple to line Z, each such path including the windings of relay R3 in series, resistor 9 and filter 12, then from line 7 through the left-hand side of office filter 12 and the primary of a transformer 13 to battery 81. Normally, relay T3 is picked up and relays R 3 energized by positive current, with their left-hand contacts closed. Relay R3 is used to mark the beginning and end of a series of code impulses and during the transmission of the series is held reversed by release of relay T 3. Each station is conditioned to respond to code over the control circuit only when relay R 3 is normal and to respond to the code steps only when relay R3 is reversed. Indications are transmitted from a station to the office by temporary connection of line wires Y, Z, by closure of line shunt contacts such as 14, 15, 16, such closure being without effect on the telephone channel because of interposed filter 12 and without effect on relay R3 which remains in its last operated position when de-energized. Each closure also results in increased flow of current from battery 81 through primary of transformer 13 at the office, a stick-polar relay OR in the secondary circuit of the transformer operates its contacts to the right on each such increase. The system as shown in Fig. 3 is used to control block signals governing train movements over a track not equipped with continuous track circuits and for reporting to the office said movements. For telephone communication the despatcher's office has a plurality of code wheels such as 89 to selectively call the wayside stations, a selector battery 85, a connector relay 86 and pole-changer relay 87, each station having a selector 72 to operate a call-bell 76. Fig. 2 shows a track diagram of an insulated detector track section with traffic governing signals IL, IR and track relay TR. A train is indicated having at its rear a magnet M for affecting inductively an inductor I in circuit with a relay S for indicating at the office whether or not a train which has just vacated the section is complete and intact, as referred to again below. The signals, as shown in the circuit portion of the diagram, are of three-colour type with lamps G, Y, R indicating respectively " clear." " permissive. " and "stop." A track stick-relay TS has a pick-up circuit closed over contacts IN of signal control relays LHS, RHS when these relays are in normal " stop position as shown and contact 18 of relay TR is picked up. The stick circuit of relay TS includes its front contact 17 and contact 18. Each signal indicates " stop " when its relay LHS or RHS is normal or when relay TS. is released. When relay TS is picked up, " permissive " or "clear" is indicated according to position of a relay DS. The signals show " stop " automatically when a train enters the track section and remain at stop after it is vacated. The subsequent clearing of either signal can be effected only if the operator restores the previously operated signal control lever to pick up relay TS. The signal relays are controlled by code impulses from the office and as described a group of four station selecting impulses is used providing, by suitable combinations of positive and negative, for code calls for sixteen stations. Each call code is followed by four function impulses received only at the selected station, three impulses controlling relays LHS, RHS, DS respectively, the fourth being available for any desired purpose such as operating a maintainer's call signal. Each code may also include four impulses transmitted over the indicator line channel for operating a group of indicating relays at the office, such as relays ITK, ISK, IHK, IDK, Fig. IB., indicating the condition of four devices at the selected station: These indications are controlled by shunt coritacts such as 15, 16, operating only at the selected station. Current is supplied from local sources having terminals B, C for operating all relays except those controlled over the line, or relays such as IHK, LHS with single windings, and which are operated to the right by connection of the negative terminal N of a second source to the right-hand terminal of its winding, terminal C being the positive terminal for this source. The station apparatus, Fig. 2, includes a starting relay ST normally energized over a stick circuit including contacts 19, 22 of relays TR, TS and when released closes contact 14 to send a starting impulse to the office; relay ST being re-energized on receipt of the corresponding code call. On the fourth code step the first indication step is transmitted under control of relay TR, the office indication relay ITK being reversed if contact 15 is closed, but restored locally to normal if contact 15 is open, to show whether the detector track section is vacant or occupied. On the fifth code step an indication impulse is transmitted to office indication relay ISK under control of relay S thus showing whether the passing train is intact by the effect of magnet M (at rear end of train) on inductor I. Relay S when energized closes its stick circuit over its contact 20 and back contact 17 of relay TS, becoming de-energized when the operator restores signal relay LHS or RHS to normal to pick up relay TS. Operation of contact 22 again releases relay ST to initiate a new cycle to cancel the train report. An indication is transmitted on the sixth code step under control of contact 4R of relay LHS, or RHS to indicate when one of these relays is reversed, and on the seventh code step under control of contact 4R of relay DS. The station apparatus also includes stepping relays 1P .. 4P picked up successively each remaining picked up till the next is fully picked up. Relay 1P picks up over back contacts 2R of line relays R<1>, R2 (if relay R3 is normal) when the stepping line channel is first opened to begin a code. Relays 2P, 3P, 4P, 1P pick up successively over front contacts 1N of relays R1 R2 on the first four impulses of a code only if those impulses agree with the code call for the station as determined by adjustable jumper connections. A stickpolar " half-step relay Y, is operated to left and right alternately over contacts B2 of the stepping relays in the intervals between code impulses to provide stick circuit connections for proper operation of these relays, stick-relay À CR- is picked up at the beginning of the fourth code step; at the selected station only, to render relays 2P, 3P, 4P at that station responsive to the fifth, sixth and seventh impulses irrespective of polarity and prepare control-receiving and indication transmitting circuits, and a slow-release relay L is energized alternately with relay 1P when the line wires are used for transmission of selector codes, back contacts C1 being included with contact 14 in the message line shunt circuit to prevent rele