Patent GB-584352-A (GB)
Title: Improvements relating to remote control apparatus for railways
IPC: B61L7/08
Filed: 1944-12-08
Abstract: 584,352. Railway signalling systems WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. Dec. 8, 1944. No. 24632. Convention date, Dec. 18, 1943. [Class 105] [Also in Group XXXVIII] A centralised traffic control system for railways uses a single line circuit with different frequency bands of alternating current for way station selection wherein for operation of apparatus at a particular way station the frequency band current for such station is modulated in accordance with the particular operation required and the corresponding return indication is given by modulation of a different frequency band also assigned to such station. For the continued control of the operated apparatus 'it is necessary that the return indication be received. The system is such that successive signals cannot be put contemporaneously at the clear aspect ; one signal must be at the caution aspect. This ensures a more constant supervision by the traffic controller. Only short-detector sections at the signals are track circuited and the picking up of the track relays is dependent on an end carriage control. Figs. 1 and 2 show rexpectively the central office and way station arrangements for the control of-wayside signals. To clear a signal LH at a way station 2 for a left-bound train the operator at the control office depresses a push 2PB and then with push 2PB still depressed sets a lever 2HL to the left. The first action causes direct current at a 75 interruption rate to be applied to a coding relay RCTM whereby alternating current from an electron tube oscillator OSC2 of frequency f10 (as determined by inductance 26 and capacity C1) is applied through a filter RF to the line circuit YZ ; the circuit to the coding relay RCTM is from source B over 75 interruption contact a of a transmitter 75CT, bus wire 75, contacts d of levers 2DL, 2HL in their mid-position (unoperated), contact c of push button 2PB, back contact c of a stick relay 2LP, and winding of coding ralay RCTM. At the way station 2 the alternating current of frequency f 10 and coded at the 75 interruption rate operates a code-following relay RCF through a filter RF, amplifier AMP and detector or demodulator DET. With a 75 code only a code-controlled signal relay RCD is energized and a front contact c thereof causes a 240 interruption rate return indication current of frequency f20 to be applied to the line circuit YZ from an electron tube oscillator OSC by the energization of coding relay ICTM from a source B over contact a of a 240 interruption transmitter 240CT, front contacts f of a short detectorsection track relay TR, b of a stick relay K, c of the code controlled signal relay RCD, back contacts d of unoperated signal relays HR, DR, front contact d of track relay TR, and winding of coding relay ICTM. At the central office this return indication 240 interruption coded alternating current of frequency f20 operates through a filter IF, amplifier AMP, and detector DET, a codefollowing relay ICF which effects the energization of an indication relay 2SK and of a code detector 2CD. A front contact a of indication relay 2SK effects the lighting of a white indication lamp WE, and also of a red indication lamp RE (over back contact a of relay 2NK) while a front contact c of the code detector relay 2CD prepares a stick circuit for the relay 2LP. The relay 2LP is picked up over a contact of the lever 2HL at the left by a circuit from source B over contact a of push button 2PB, front contact c of indication relay 2SK, contacts f of relay ILP and lever IHL for the next wayside signal provided these have not been operated for a right hand train movement, contact e of lever 2HL at the left, and winding of relay 2LP; the relay 2LP then remains energized over its stick circuit from a source B over stick contact a, front contact c of code detector relay 2CD, contacts f of relay ILP and lever IHL (lever IHL not operated for right bound train movement), contact e of lever 2HL at the left and winding of relay 2LP. With lever 2HL at the left and with relay 2LP energized the coding relay LCTM is operated with direct current at 120 interruption rate from contact a of transmitter 120CT, bus wire 120, contact b of lever 2DL in midposition, contact b of lever 2HL at the left, front contact b of relay 2LP, and winding of coding relay LCTM. The coding relay LCTM applies 120 interruption coded alternating current of frequency f11 (as determined by condenser C1 and part inductance 26) to the line circuit YZ so that at the way station 2 the code following relay LCF is operated to effect the energization of code-controlled signal relay LCD and (through decoding unit 120DU) the signal relay HR. This effects the lighting of the lamp Y of wayside signal LH over front contacts b of code-controlled signal relay LCD and of track relay TR, back contact b of signal relay DR (operated only by 180 interruption code), and front contact b of signal relay HR. A stick relay K is also dropped by the opening of back contact f of signal relay HR. A return indication is given by the coding relay ICTM being operated with 120 interruption direct current over contact a of transmitter 1200CT, front contact d of signal relay HR, back contact d of signal relay DR, and front contact d of track relay TR. At the central office this 120 interruption code causes indication relay 2YK to be energized thereby to light an indication lamp LYE over back contacts a, b of indication relays 2SK, 2NK, and front contact a of indication relay 2YK and contact a of lever 2HL at the left. It will be seen the stick relay 2LP is only maintained energized, as is necessary for the continued clearance of the signal, if return indication code is received. To set the signal to the G aspect, the lever 2DL is set to the left whereby the coding relay LCTM. is operated with direct current at 180 interruption rate from contact a of transmitter 180CT, bus wire 180, back contact e of relay ILP for the next wayside signal, contact b of levers 2DL and 2HL at the left, front contact b of stick relay 2LP and winding of coding relay LCTM, which relay applies alternating current of frequency f11 and interrupted at 180 rate to the line circuit YZ. At the way station this 180 interruption code effects the energization of signal relays LCD and DR, the latter being energized from decoding unit 180DU over a front contact a of relay HR which is slow to release. Thus lamp G of signal LH is lit over front contacts b of signal relay LCD, of track relay TR and of signal relay DR. It will be noted that if relay ILP were energized by a signal at the next station having been operated then contact e of relay ILP would connect to the bus wire 120 instead of bus wire 180 and signal relay HR would remain energized instead of relay DR becoming energized ; thus if two successive signals are operated they can only show the Y aspects. A return indication is given by the coding relay ICTM being operated at 75 interruption rate from the contact a of transmitter 75CT, front contacts d of signal relay DR and track relay TR. At the office this 75 interruption rate code effects the energization of only code detector 2CD ; an indication lamp LGE is lit over back contacts a, b, a of indication relays 2SK, 2NK, 2YK, front contact a of code detector 2CD and contact a of lever 2HL at the left. When a train passes the cleared signal LH the track relay TR drops and its back contact b lights the lamp R of the signal LH. Also as stick relay K was previously dropped by the opening of back contact f of the signal relay HR this results in the coding relay ICTM being operated at 180 interruption rate over contact a of transmitter 180CT and the back contacts b, c, c, d of relays K, RCD, LCD (dropped by cessation of operation code when indication code derived from front contacts d of relays DR, TR ceased and caused stick relay 2LP to drop), TR. This 180 indication code effects the energization of indication relay 2NK a front contact a of which lights the red indication lamp RE. When a magnet on the end carriage of the train passes over an inductance core J a relay S is operated to effect the energization of relay K, back contact b of which opens to stop the transmission of 180 indication code and so causes the red lamp RE to be extinguished so denoting the whole of the train has passed. The operator then returns the levers 2HL, 2DL to the mid-position and operates push button 2PB which causes a 75 interruption code of frequency f10 to be transmitted to the way station to effect the energization of the relay RCD a front contact d of which closes to cause pick up of the track relay TR. With track relay TR closing its front contact f and relay K closing its front contact b an indication code of 240 interruption rate is given from the transmitter 240CT over the above contacts and front contact c of relay ROD, back contacts d of signal relays HR, DR, front contact d of track relay TR. At the office this 240 interruption code effects the energization of indication relay 2SK a front contact of which lights indication lamps WE, RE, the latter over back contact a of indication relay 2NK.