US1791168A - Railway signaling - Google Patents

Description

Feb; 3, 1931. E, C, sANE-T 1,791,168

RAILWAY SIGNALING original Filed'oct 15. 1925 rnfaue/vcy am JM Patented Feb.' 3, 1931 UNITED s'rmssA Perser orner.

EDWARD o. snsnnrr, or WASHINGTON, Drsrnror orlooLnMBA, AssIGNoR To THE UNION SWTCH & SG'NAL COMPANY, OF SWISSVALE, PENNSYLVANIA, ,A CORPORA- TION OF PENNSYLVANIA' RAILWAY SIGNALING Application led October 15, 1925. Serial No. $2,542. Renewed August 27, 1928.

Afrom the track rails through a lvehicle carried vtra-nslatinob device enero` inthe form C) D of electrical impulses, -the character 'orfre-L quency of the impulses being varied in ac,

cordance with traiiic conditions, and signals or train control mechanism selectivelygoverned by vthe impulses 1n accordance withv the lparticular code of impulses received.

An object of the invention is to provide a system of this character in which the codes et impulses are generatedV at a. single station and transmitted to the track rails through line Wires or otherwise. By `Ygenerating the impulses at a single station, l eliminate separate coding devices foreach clock of the -track and therefore very Vmaterially simplify the apparatus while rendering the codes absolutely uniform throughout the system. v

Another object is to provide .a rcode system ot' train control employing` insulated blocks without thel necessity of traclr relays. For the attainmentof this object I provide a system in whichl the impulses `are applied to the rails at the exitends of the blocks and are transmitted to the next block in rear, preferably through synchronously closed shunts around the insulation joints. Obviously, the elimination of the track relays gref duces the system to minimum simplicity. and m rcover increasesthe safetyk Afactor.

A still further objectv is to providea code system in which the codes consist ofalternatine currentimpulses of different frequencies. Forexample, the clear code lmay consist of impulses of three different fre- Vquencies periodically transmitted; a more pulses et thesame frequency.

restrictive code, of impulses yof two frequencies, and a still more restrictive code, of 41msystem is usedwithout track relays and with or kwithout insulated, joints in .the traclr rails` these codes are producedby periodically 's-aipplying to the rails at longitudinally spaced points alternating currents of dirlerlllhere they ent frequencies, respectively, whereby a vehicle -on thetrack provided with translating devices respectively responsive tothe diil'erentj frequencies-will havefal-l, some or none of its :translating devices `periodically energized according to the conditions of tra'lic. The impulses of different frequencies may be, but are not necessari-ly, transmitted asynchronously. 1

The vinvention'will be particularly described with reference to the lacconipanying drawings, which show'V diagrammatically is equally well-adaptedl for traffic in the opy posite direction. Relays 10a, 10b, 102.10% 10e, etc. are located adjacent the junctions of ,the blockszand are connected to the sec.-

ondaries of "transformers 11, the primaries"i of which are .connected to line wires 12 eX- tending from a station throughout the signailed territory. At :this station, switches 13 14 fand 15 are operated successively and periodically to 4connectsources -o alternatingcurrent 16, 17 and 18 across the 'line Wires 12.' As illustrated, switches 13, lll and 15 are operated respectivelybycams 19 2O and 2l which arey rigid with Ya worm LwheelQQ driven by a worm 23 fixed tothe armature f2 24.01 a jmotor. The raised portions of cams 19, 2G andj21 are angularly displaced ,and

lays throughout. `the system are'made selectively responsive to the frequency of alternatur 16; relays lOuand 10d Lare responsive to the alternator 18; and Vrelays 10c and'corresponding relays are responsive to 'alternator l The. al-

Cil

1'?. That is to say, the relays are arranged in groups of three, relays of the same group being responsive to diiferent frequencies and corresponding relays of the several groups being responsive to the same frequency. Relays 10b, 10c and 10d constitute one group, being respectively responsive to the frequencies of alternators 16, l? and 18. Relay 10e is the first of the following group and relay 10EL is the last of the preceding group.

lt will now be clear that when the alternator 1G is connected to the line wires, relay 10b, and corresponding relays throughout the system will close their front contacts and open their back contacts, and that relays 10c and 10d are similarly operated respectively when alternators 1'? and 18 are connected across the line wires. lt will be observed that when the front contacts of the relays are closed the secondaries of the transformers are connected across the rails and the shunts around the insulated joints through the back contacts of the relays are opened. As is customary, resistances lt mayV he inserted in the conductors connecting the secondaries of the transformers to the track rails to prevent dead short circuiting of the transformers by the wheels and aXles of the vehicles.

The track system above described is adapted to control the display of signals on the track or on the cab of a locomotive, or on both. rlhe drawing shows cab signals only, vehicle being indicated in block B provided with. signaling apparatus responsive selectively to the current impulses flowing in the track rails. rl`he vehicle is provided with a coil 25 carried adjacent the rails so as to have electrornotive forces induced therein by the track currents. Coil 25 is connected to a suitable amplifying device 26, whereby the feeble cur-rents picked up from the track are amplified and delivered to relays 27, 28 and 29, which are inade selectively responsive to the frequencies of alternators 16, 17 and 18. The amplifying device 26 may include an amplilier for each frequency7 as is old and well known in the art.

ln the instantaneous positions of the parts shown by the drawing, alternator 16 is connected to the line wires vby switch 15, and relays lOl and 10e are accordingly energized. Current is flowing from the secondary 11 through the front contacts of relay 10e, through the track rails` of block D, through the shunts around the insulated joints between blocks l) and C, closed at back contacts of relay 10, through the rails of block C, through the shunts around the insulated joints between blocks C and B, closed at the back contacts of relay 10, through the rails of block B, and through the wheels and axles of the vehicle. This current has the frequency of alternator 16, and accordingly the relay 2i' on the vehicle is energized. When switch 15 opens and switch 13 closes alternator 18 will be connected to the line wires and relay 10e will drop and relay 10d will pick up. Current from alternator 1S will now flow through the front contacts of relay 10d from the secondary of transformer 11, through the rails of block C, through 'the shunts around the insulated joints between blocks C and B, and through the wheels and axles of the vehicle. telay 29 on the vehicle will accordingly be energized. l/Vhen switch 13 opens and switch 1li closes current from alternator 18 will be cut off and current from alternator 17 will flow through the front contacts of relay 10, through the rails of block B and through the wheels and axles of the vehicle, causing the cab carried relay 28 to pick up.

From the foregoing, it will be understood that under normal, or clear conditions, the vehicle carried coil 25 will pick up successively currents of the frequencies of alternators 16, 1"? and 18.

Suppose now that with the vehicle shown in block B, there should be an advance vehicle in blc-ck l. lt will be obvious that the vehicle in block B can receive current only from the operations of relays 10 and 10d. s this current is in impulses of the frequencies of alternators l? and 18, the cab relays 28 and 29 will be intermittently energized, but relay 27 will be co? inuously deenergized.

If with the vehicle in block B there should be an advance vehicle in block C, the vehicle in block B could receive current only from the operation of relay 10C. rllhis current would be in the forni of impulses of the frequency of alternator 17. l-lence under these conditions, the cab relay 28 would be inter-- inittently energized, but relays 27 and 29 would remain continuously deenergized.

Under clear conditions therefore, relays 27, 28 and 29 are successively and periodically energized. Under caution conditions, only two of the cab relays will be intermittently energized. The relays that will be intermittently energized under caution conditions may be 27 and 28, or 2S and 29, or 27 and 29, depending upon the particular two frequencies received and therefore depending upon the particular pairs of relays l0 between the vehicles. Under danger conditions, only one of the relays 27, 28 or 29 will be intermittently energized. t may be any one of the relays, as will be obvious.

Any suitable signaling mechanism may be provided selectively controlled by the relays 27, 28 and 29. iis shown, relay 27 controls slow release relay 3G; relay 2S, a slow release relay 3l; and relay 29, aslow release relay 3 2. These relays control the circuits of a clear signal lamp a. caution signal lamp 3e and a danger signal lmnp Under clear conditions the slow relays 30, 3l and S2 are continuously held up, as the interval between successive encrgizations of each is only two seconds. l-lence lSG under clear conditions, the circuitof'lamp 3S is closed through the upper `front contacts of relays 3.0, 3l and-32. y

Under caution conditions, only two of the relays 30, 3l vand 32 are intermittently energized. Hence the cir-cuit of the elearlamp is interrupted at a rontcontact of one ott-hose relays. If relays i3@ and 3l are the pair intermittently energized, the circuit of the eaution lamp 34 will-loe closedthroughront contacts E6-and back contacts 37. 1F28 land29 are intermittently energized, fthe circuit of this lamp will be closed at hack contacts 38 and fro-nt contacts).- It relays 30 and 32 are intermittently energized, the circuit of s id lamp will he closed at front contact d0, hack contact 4l and front contact 4t2.

Under danger conditions, 'only one of 'the relays is intermittently energized. one -is 30, ther circuit of danger' lamp 35 will he closed through front contact 43 andhack contacts lla; it 3l, the circuit will he closed through front contact 45 and hackv contacts 46 andY 47; if 32, the .circuit will he closed through front contact i8 and hack contacts il-9. 1 Y

Altho I 'have Yparticularly described a single system embodying my invention it will be obvious to those skilled in .the-art that the principles of the invention can4 readily, he embodied in systems of various constructions and I therefore do not intend to .limit myV invention except as'deiined in the claims, s

l make no claim, in this application to the combination of means Vfor supplying coded or periodically varied current tothe trackway and train carried means controlled hy said trackway current and including` slowv acting means for bridging tlie'intervalshetween vperiodic variationsy in such current, Y which Ycombination forms the suhgect matter Y of application Ser. No. 215,318, iiledfleugust 1927,' by Arba G. lVilliamson.-

l claim: V l. A railway signaling system, comprising a track divided into insulated blocks, means for periodically connecting-a source of current across the rails vat the exit end of a block and synchronously connecting va shunt around an insulated joint at the entrance ot said block, whereby current from said source is transmitted to the block in the` rear, a translating device responsive to current flowing through the rails, and signaling 4means controlled hy said translatingv device.

2. A'railway signaling system, comprising 4a stretch of track, means for periodically and successively connecting sources of current across the track ata plurality oi; spaced points, said means comprising a relay at each or" said points and means ata single station controlling said relays, tran.'1k ing devices responsive to energy flowing through the track rails, and signals selectively actuated by said translating devficeszin accordance l.with y,

l1 this the number ciipoi'nts from which'energy lis transmitted thereto. j y

3, A railway signaling system, comprising a stretchottrack, means tor periodically and successivelyconnecting sources ot current across the `track rails at a .pluralityof spaced points, said means comprising a lrelay at each of said points, a line .vire'to which the rela-ys are connected, and' switch' mechanism periodicallyand successively connecting currents of different character to said line wire, translating.Idevices'responsive -to energy flowing through the track rails,'and signals selectively actuated by said translatingy devices; in ac-. cordance 'withk the numberv oi points lalong the track trom which current is transmitted thereto. v

4i. A railway signaling system comprising a stretch of track, means .for periodicallyand successively transmitting current otditlerent character 'th rough the track rails from ,aplurality oi' spaced points along the track, said connected, and periodically operatingswitch 1;,

mechanism connected to said line wire, translating rdevices responsive to energyr flowing through the track rails, and signals selectively controlled-hy' said translating devices" in accordance with the character of current transmitted through' the rails to said translating devices.y f i .Avrailwaysignaling system, comprising astretch of track, means for periodically and successively 'conneetin' electric-al energy across the track rails a piuralityof spaced points, said means `comprising selectors at eacho'f said points and Ymea-ns at a single stationV controlling said selectors, translating-devices responsive tof energy `flowing rthrou the track rails, and.signals controlled by said translating devices. 5 y g 6. A railway signaling system, comprising a stretch ot track, nies` for periodically and successively connecti Ag electrical energy across the track rails at aplurality of spaced ioints, said Ameans .cor prising selectors at each of said points and means a sing-'lestetion controlling saidselectors, transl ating-,devices responsive to energy flowing through the track rails,and signals contr d hy said translating devices and selectively actuated in accordance with the number o'iijioints from which energry is transmitted thereto. l

7. ln a railway signaling system, a track divided in-to insulated blocks, means for successively and periodically connecting alternating energy of different Arequ-:uicies acrss the rails at the exit end of each block, signaling mechanism selectively -es'ponsive 'osa'.id frequencies. y 8. In a railway signaling system, a stretch of track, Vmeans for successivelyand periodispaced points, and signaling mechanism for the stretch selectively responsive to said frequencies.

9. In a railway signaling system, a track divided into insulated blocks, means for successively and periodically applying to the track rails of a block alternating energy of three frequencies under clear traiiic conditions, two frequencies under caution conditions, and one frequency under danger conditions, a translating device, selectively responsive to said frequencies and clear, caution and danger signals actuated by said translating devices.

10. In a railway signaling system, a track divided into insulated blocks, line conductors, means at a central station for connecting to said conductors successively and periodically sources of alternating currents of different frequencies, a relay for each block connected to said conductors, said relays being arranged in groups with relays belonging to the same group respectively responsive to currents of different frequencies and with corresponding relays of the several groups responsive to current of the same frequency, said relays when energized connecting said conductors across the track relays at the exit ends of the blocks, and means permitting current to flow from said conductors through the rails of a number of blocks preceding any blocks across which the conductors are connected by an energized relay, said number being one less than the number of relays constituting a group.

11. In a railway signaling system, a track divided into insulated blocks, sources of currents of different characters, selectors associated with eacli block operated from a single station for connecting said sources successively and periodically across the rails at the exit end of each block, a translating device selectively responsive to said currents and signaling mechanism controlled by said translating device.

l2. In a railway signaling system a track divided into insulated blocks, sources of currents of different frequencies, selectors associated with each block operated from a single station for connecting said sources successively and periodically across the rails at the exit end of each block, aI vehicle travelling on the track, translating devices on the vehicle selectively operated in accordance with the frequencies of the current received and signaling mechanism controlled by said translating devices.

18. ln a railway signaling system, a vehicle travelling on a track, translating devices onV mined traflic conditions, and a signal held at one indication only so long as said translating devices are thus energized.

14. A railway signaling system comprising a wayside conductor, selective means controlled from a central station for connecting electrical energy to said conductor at spaced points, said selective means bein@- arranged in successive groups and in the same group operating to connect energy to said conductor successively, a vehicle having a translating device responsive to current iiowing through said conductor, and train governing mechanism selectively controlled in accordance with the number of points from which energy is transmitted to said translating device.

l5. A railway signaling system comprising wayside conductor, frequency selective relays located at spaced points along the trackway connected to a line wire leading to a central station, means for periodically connecting alternating currents of diferent frequencies to said line wire to selectively energize said relays, said el ys when energized connecting electrical energy to said conductor at spaced points thereon, a vehicle having a translating device responsive to currents flowing through said conductor and train governing mechanism controlled by said nslating device. f 2 6. ik railway signaling system comprising a. wayside conductor, selective devices controlled from a central station for connecting electrical energy to said conductor at spaced points, said selective devices being arranged in successive groups and the same group transmitting energy to said conductor .successively and corresponding devices in the several groups transmitting energy to said conductor synchronously, a vehicle having` a translating device responsive to energy flowing through said conductor, and train governing mechanism controlled by said translating device.

17. A railway signaling system comprising al stretch of track, selective devices controlled from a central station for connecting Aelectrical energy across the track rails at spaced points, said devices arranged in suc-A cessive groups and in the same group 'transmitting energy to said rails succei" rely and corresponding devices in the sever..i l groups trairf-mitienergy to said s synchronously, vesicle nav a transitatimil device responsive to energy flowing through said rails, an( train governing mechanism controlled by said'translating device.

18. A railway sien aling system co nprising a stretch of track, a line wire leading to a central station, frequency selective devices connected to said line wire and adapted to transmit energy to the track rails at spaced points, said devices being arranged in succes ive groups and the same group transmitting energy to the rails successively, means at the central station for successively and periodically connecting sources of alternating current of different frequencies to'saidlinewire, andl train governing. devices responsive to energy flowing through the rails.

19. A railwaysignaling system comprising a ,waysidel conductor, a vehicle having a translating device responsive to current flowing through said conductor, a line Wire leading to a central station, frequency. selective` devices connected to said line wire and adapted to transmit Venergy to said, conductor at spaced points, said selective devices being arrangedl in successive groups and 'in the same'group adapted to transmit energy of different frequencies, and means at the central station Vfor successively and periodically connecting sources of alternating current of different frequencies to said line wire.

20. A railway signaling system comprising a track divided into insulated blocks, means for periodically connecting electrical energy across the rails at the exit end of a block, means for transmitting said energy to the rails of the block immediately in rear, and signaling meansresponsive ,to said energy.

21. A railway 'signaling'system comprising a track divided into insulated blocks, means for each block operating to connect energy intermittently across the rails at the eXit ends of the blocks, said means operating to connect energy asynchronously in the case of a plurality of successive blocks, means for transmitting energy fromone block to the block immediately in rear thereof, and a vehicle travelling on the track having a translating device responsive to said energy.

22. A railway signaling system comprising a track dividedA into insulated blocks, Vshunts aroundr the insulated joints Y defining the blocks, means .for periodically connecting electrical energy across the rails at the exit ends ofthe blocks, said means being arranged in successivegroups and in the same group operating kto 4connect energyy across the rails successively while corresponding means of the several groups operate to yconnect energy across the rails synchronously, each of said means when operating to connect energy across the rails opening the shunt around the adjacent insulated joint, and a vehicle travelling. on the track having a translating device responsive to said energy.

23. A railwaysignaling system comprising a stretch of track, a -line'wire leading to a central station, selective'relays connected to saidfline wire at spaced points, said relays being arranged in successive groups and in the same group Vadapted to operate succes' sively, means at the central station controlling said relays, electrical connections to the track rails controlled by said relays, and train governing devices responsive to energy flowing through the rails. 1

24. A railway signaling system comprising a stretch of track, selective devices at spaced points along the track controlled from a cenl train governing means controlled by saidy Atranslatlng device.

26. A railway signaling system comprising a track divided by insulated joints into blocks, means for connecting electrical energy across the track rails of the several blocks, means for periodically bridging said insulated` joints, said means operating to bridge adjacent insulated joints asynchro nously, a vehicle having ak translating device responsive to current flowing in the rails, and train control mechanism governed by said translating device.

27. A railway signaling system comprising in combination withy two/sections of track divided by an insulated joint, means for connecting electrical energy across the track rails at the exit ends ofeach section, means for periodically bridging the insulated joint between said sections, whereby" energy yis transmittedV from the forward section to the rear section, and a vehicle havin train control mechanism responsive to the currents flowing in the trackrails.

28. In arailway traflic controlling system, in combination, a stretch of track, line wires extending alongsaid track, electrical connections between the line wires and track at longitudinally spaced points thereof, a source of energy, and constantly operating switch mechanism controlling the connection of said sourceof energy to `said line wires, whereby periodic current impulses are produced in said wires and in said track.

29. In a railway traliic controlling system, in combination, Va stretch of track'divided into insulated blocks, lin-e wires extending alongn said track, electrical connections between the line wires and the exit ends of the blocks, a source o-f energy adapted to be con'- nected to said line wires, and constantly operating switch mechanism controlling the application of energy to said wires, to cause current impulses inthe line wires and track rails.

30. In a railway tralhccontrolling system, a stretch of track divided into insulated blocks, sources of current of different frequencies,

and means for connecting said sources alterfil) nately and periodically across the track rails at the enit ends of the blocks.

3l. ln a railway traflic controlling system, in combination, a stretch of track divided into insulated blocks, line wire extending along said track, electrical connections between said. line wire and track at the exitends of the blocks, and means for producing periodic impulses of alternating current in said line wire to cause periodic current impulses in the track rails.

32. ln a railway traliic controlling system, in combination, a stretch of track divided into insulated blocks, line wires extending along said track, electrical connections between said line wires and the track at the exit ends of the blocks, a source of alternating energy, and constantly operating mechanism for controlling the application of said energy to said line wires to produce periodic impulses of alternating current in the track rails.

33. in a code continuous indication system, a stretch of track divided into insulated blocks, and means for producing a code of current impulses in the track rails, said means comprising a constantly operating coding device at single station and means for transmitting the current impulses produced by said device to the track rails of the several blocks of said stretch. 1

311-. A railway trafhc controlling system comprising, in combination, a stretch of track divided into insulated blocks, line Wires eX- tending along the track, sources of current of different frequencies, constantly operating means for periodically controlling the application of said sources to the line wires, means adjacent the block junctions for selectively transmitting the alternating currents flowing in the line wires to the track rails, a vehicle travelling on the track having translating devices selectively actuated by said currents and train control devices governed by said translating devices.

35. A railway trafhc controlling system comprising, in combination, a stretch of track, line wires extending along the track, sources of current of differentfrequencies, constantly operating means for controlling the application of said sources to the line wires, frequency selective devices for transmitting the alternating currents flowing in the line wires to the track rails, a vehicle travelling on said track having translating devices selectively actuated by said currents, and train control devices governed by said translating devices.

36. ln a. railway traffic controlling system having a stretch of track including an insulated block, line wires extending along the track, a source of alternating current, constantly operating means for periodically applying said source to the line wires, a frequency selective device connected to the line vwires adjacent the exit end of the block adapted to transmit said alternating current to the trackv rails, a vehicle travelling on the track having a coil disposed in inductive relation to the rails, a frequency selective translating device connected to said coil, and train control means governed by said translating device.

37. In a code continuous indication system, a stretch of track and means for intermittently connecting sources of current across the track rails at longitudinally spaced points thereof to produce codes of impulses in the track rails, said means comprising a constantly operating coding device at a single station which controls the application of energy to the rails throughout the system.

38. ln a code continuous indication system, a stretch of track and means for intermittently connecting sources of current across the track rails at longitudinally spaced points thereof to produce codes of impulses in the track rails, said means comprising a constantly operating coding device at a single station and selective devices at longitudinally spaced points of the track governed by said coding device, said selective devices governing the lapplication of energy to the track rails.

89. ln a railway traffic controlling system, in combination, a stretch of track, line wires extending along the track, sources of current of different frequencies, constantly operating mechanism for periodically controlling the application of said sources to the line wires, and frequency selective means at spaced points along the track for selectively transmitting the alternating currents flowing in the line wires to the track rails.

4:0. ln automatic train control system, in combination with a stretch of track, means for intermittently applying to the rails of said stretch at longitudinally spaced points thereof alternating currents of different frequencies, a vehicle having translating devices respectively responsive to said frequencies, and signals selectively controlled by said translating devices.

l-l. In an automatic train control system, in combination with a stretch of track, means for periodically applying to the rails of said stretch at longitudinally spaced points thereof alternating currentsy of different frequencies, a vehicle having translating devices respectively responsive to said frequencies, slow release relays respectively controlled by said translating devices, and train control mechanism governed by said relays.

42. A code-continuous-indication system comprising in combination with a stretch of track and a vehicle travelling thereon, means for periodically applying to the rails of said stretch at longitudinally spaced points alternating currents of different frequencies, so that the vehicle will receive impulses of Y frequencies according to the number of points 'from which energy is transmitted thereto,

and signals on the vehicle sek-ictivelycon-l trolled by said currents. v

43. An automatic train 4control system comprising, in combination with'a stretch of track, a vehicle travelling thereon, a plurality of translating devices onvsaid vehicle, traiiic controlled means for periodically. transmitting` through said translating devices, respectively, alternating currents of different frequencies, whereby said translating devices are periodically energized under predetermined trai'lic conditions, slow act-ing'means controlled by said translating devices, and signals controlled by saidfslow acting means.

44. An automatic train control system comprising, in combination with a `stretch of track divided into insulated blocks, traflic cont-rolled means for applying alternating currents of different frequencies to the eXit ends of the blocks periodically, a vehicle on the track having translating devices respectively responsiveto said alternating currents, whereby said translating` devices are intermittently energized under predetermined traffic conditions', slow release relays controlled by said translating devices, and signals governed by said slow release relays.

45. An automatic train control system comprising, in combination with a stretch of track divided into insulated blocks, traffic controlled means for periodically applying alternating currents of two different frequencies to the exit ends or the blocks under certain traliic conditions and for periodically applying alternating current of one frequency to the exit ends ot the blocks under more restrictive trafiic conditions, a vehicleon track divided .into a plurality of sections,

vmeans for normally supplying each section with alternating current periodically varying in Irequency, means responsive to traflic conditions tor controllingthe supply of such current to each track section,and train carried governing lmeans controlled by energy received from the trackway and including a plurality of devices each selectively responp signature.

EDWARD C. SASNETT.

whereof I hereunto affix my the track having translating devices respectively responsive to said frequencieaand signals selectively controlled by said translating devices. Y

4:6. In combination, a stretch of railway track divided into 4a plurality of sect-ions, a line circuit extending along said stretch, a circuit controller comprising a periodically operated-contact, means including said contact for supplying current to said line circuit, means for each section responsive to thecurrent in said line circuit for supplying track circuit current to the rails of the corresponding section, and governing Vmeans responsive to such current.

47. In combination, a stretch of railway track divided into a plurality of sections, a line circuit extending along .said stretch, means for supplying said lline circuit with current"periodically varying in frequency, means for supplying'eachsection with current' from said line circuit, and governing means responsive to the frequencyl of such current. .Y

48. In combination, a stretch of` railway

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