US2505988A - Coded signaling apparatus - Google Patents

Description

may 2, 1950 E. E. @HAGAN ET A1..

CODED SIGNALING APPARATUS Filed Aug. 6, l947 @mi BSS-ww QM.

wmp ,Y

Patented May 2', 119.506

'2,505,988 ICE coDED SIGNALING APPARATUS Bernard E. OHagan, deceased, late of SwsSval; Pa., by Clare OHagan, administratrix, Swissvale, la., and Paul N. Martin, Penn Township, Allegheny County, Pa., assignors to The Union Switch and Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application August 6, 1947, Serial No. 766,502

13 Claims.

This invention relates to coded signaling apparatus, and particularly to improved means for producing coded impulses of energy suitable for use in coded signaling systems.

`In systems of the type described, it has been the practice to code the supply of energy by means of a recurrently operated contact of a transmitting relay or other device. Due to mechanical limitations imposed by the necessity for fast operation, low operating power consumption, etc., it is necessary that these contacts be of a light duty construction. As a consequence, where conditions are encountered in which the amount of power controlled by these contacts becomes relatively great, the contacts are unable to withstand the heavy loads imposed upon them in interrupting a current of relatively high amperage, and their life is considerably decreased.

It is an object of this invention to provide improved means for supplyingr impulses of energy to a coded signaling system.

Another object of this invention is to provide improved means of the type described, in which the power load is governed by grid-controlled rectifier tubes which are controlled by the cond tacts of the coding device or transmitting relay. A further object of this invention is to provide improved means for alternately connecting across the rails of a track section a code-following relay and a pair of conductors to which energy may be supplied from a source, in which the supply of energy from the source to the conductors is interrupted before the connections of the conductors to the track rails are interrupted to connect the code-following relay to the rails.

Another object of this invention is to provide means for insuring that large amounts of current supplied to a load froma source through contacts of relays will be interrupted prior to the opening of the contacts and will be established only after the closing of the contacts.

A further object of the invention is to provide in ya, coded signaling system means for recurrently connecting a pair of conductors to the secondary Winding of a transformer, together with means for controlling the circuit of the transformer primary winding so that the supply of energy to the transformer primary 4winding is interrupted before the circuit from the transformer secondary winding to said conductors is interrupted.

In practicing this invention there is provided a rst and a second code-transmitting relay which have contacts which are operated `between a first and a second position substantially in synchronism. When the contacts of the first code-transmitting relay move to their second position they establish circuits for rendering electron tubes conducting and forsupplying energy through these tubes to a pair of conductors. At

this time the contacts of the second code-transmitting relay establish a circuit in multiple with the circuit established by the contacts of the first, code-transmitting relay for supplying energyA through the electron tubes to the conductors. On movement of the contacts of the rst codetransmitting relay away from their second posi-v tion the electron tubes are rendered non-conducting, while the second code-transmitting relay thereafter maintains the circuit for supplying energy through the electron tubes to the conductors until the tubes cease to be conducting.

Since the second code-transmitting relay establishes a circuit for supplying energy through .ie electron tubes to the conductors at the time the contacts of the rst code-transmitting relay interrupt the circuit which they control for supplying energy through these tubes to the conductors and as the contacts of the second codetransmitting relay do not interrupt the circuit for supplying energy through the electron tubes to the conductors until after the tubes have ceased to be conducting, it follows that the contacts of neither of the code-transmitting relays are required to interrupt the supply of energy to the conductors, Hence the relay contacts are not subjected to the arcing and burning which would occur if current were supplied through the contacts at the time they are opened, and the life of the contacts is therefore greatly increased. In addition, when the contacts of both of the4 code-transmitting relays are in their first position a code-following relay is connected across the conductors over a circuit which includes contacts of the two transmitting relays in series so that this code-following relay is not connected.

with the conductors until the supply of energy to the conductors is cut off.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

Two forms of coded signaling apparatus ernbodying this invention will be described and the novel features thereof shall then be pointed out in claims.

In the accompanying drawings,

Fig. 1 is a diagrammatic view of a portion of a coded track circuit railway signaling system having means embodying our invention for supplying impulses of energy to the rails, and

Fig. 2 is a fragmentary view of a modification of Fig. 1. Y

Similar reference characters refer to similar parts in each of the two views.

Referring to Fig. 1, there is shown therein a section of railway track T having track rails I and 2 which are isolated from the rails of the adjacent section by the usual insulated joints 3. Traffic normally moves through the section T in the direction' indicated by the arrow, that is,`

responsive to the occupancy of the `section T, and Y is operated by coded feed back energy supplied from the entrance end of section T.V

The equipmentl at the entrance end of section TV comprises a code-following track relay TR, which is of a type the contacts ofY which are biased to their lower or released position and pick up when and onlyfwhen-energy iiows through the winding inA the direction indicated 'by the arrow, that is, -from left to right; an impulse relay IR; an impulse transformer IT; a decoding transformer DT; a code-detecting relay HR, which is of a type the contacts of which are slightly slow in pickingup and reieasing; a decoding unit IBDDU whichV supplies Venergy to a decoding relay DR; and a feed back battery IB. At the exit end of section T, the equipment comprises a code following approach relay AR, which is of a type similar to the track relay TR; a first code-transmitting relay CTPR; a second or repeater code-transmitting relay CTPPR; code transmitters I80CT and'Y TSCT; a control relay CR; a decoding transformer AT, which is similar to the decoding transformer DT', an approach repeater relay APR, which is of a type which is slow in picking up and releasing its contacts; a track rectifier TRX fed by a track transformer TT; a power transformer PT; a time element relay TER; a limiting impedance R3; vand a pair of thyratron tubes VA and VB, with vtheir associated condensers Ca and Cb and their associated resistors Ra and Rb.

At each end of section T, in addition to the apparatus named above, there is provided a source of Vdirect current, not shown, the positive and negative terminals of which are designated B and C, respectively. Additionally, at the exit end of section T, there is provided a source of alternating current, not shown, whose terminals are designated BX and CX.

The thyratron tubes VA and VB are of a wellknown type,.each having a cathode 2i), av heater 2l, a grid 22, and a plate or anode 23, all enclosed in a gas-filled envelope. Tubes of this type are characterized by low voltage drop between anode and cathode, high current handling capacity, andv by the fact that the current cannot be controlled by the grid potential after conduction through the tube is once initiated. The conduction can only be stopped by reducing the -potential between anode and cathode to a value below the ionization voltage of the gas enclosed in the tubei Power for the heaters 2l of tubes VA and VB, andbiasvoltages for the grids 22 of tubes VA vand VB are obtained from the power transformer PT, which Yhas its primary winding 2li continuously connected to` the source of alternating current energy. Aseconda-ry winding 26 provides alternating current for the heaters 2l of tubes VA and VB through the connectiondesignated X and Y.

, Energyisy also supplied from winding 26 to the time element relayTER, which is of atype the Y contacts of which when released will pick `up only aftera .predetermined -t'i'mehas elapsed after energy is supplied to the relay winding. A front contact 28 of relay TER governs the supply of alternating current energy to the anode-cathode circuits of'tub'es VA and VB so that in the event that the supply of energy to the primary winding of transformer fPT is cut oi and is thereafter restored, energy will not be supplied to the anodecathode circuits of tubes VA and VB until sufficient time has elapsed for the heaters 2l of tubes VA and VB to heat the cathodes to proper operating temperature.

The grid 22a of tube VA is provided with an alternating current bias voltage by the circuit including secondary winding 30 of transformer PT, and the grid A`221; of tube V12 is provided Awith an alternating 'current bias voltage lby the circuit including secondary winding.l 32 of transformer PT.

When 'the instantaneous vpolarity of the alternating current Vsource is Such that terminal BX is positive with respect to terminal CX, the cathode 20a. of tube VA is positive with respect to the yanode 23a of tube VA, and' current cannot iiow throughtube VA.- At this time the anode 23h of tube VB is positive with respect to its cathode-20h andif the lgrid 22h of tube VB is also positivo, tube VB will conduct. However the secondary winding 32 Aof transformer PT is constr-ucted and arranged-so that ywhen the anode orV plate 23h of tube VB has a positive potential, the gridY 22h of tube'VB will have :a lnegativepotential with respect to the 'cathode 20c, and as av result the tube V-B will 'not-:conduct When `the instantaneous 'polarity of the 'alternating current source is such that terminal CX is positivewith respect to terminal BX, the anode 23a of tube VA is `posi-tive and its cathode 2lla` is negative. However, the polarity of the energy supplied from the seconda-ry winding 30 of transformer PT is such that-the grid 22a of tubeV VA has a negative potential with respect to the cathode 20a, and as a result, tube VA will not conduct. Also, at this time the cathode '20h of tube VB has a positive potential with respect to its anode 23h and tube VB will; not conduct.

From the foregoing itY will be seen that the apparatus is arranged so that when-'the contacts of relay C'IPR` are open the polarity of energy supplied to the anodes'of tubes VA and VB together with the polarity of bias voltage applied to their .grids is such `that the tubes normally will not conduct.

When frontV contact 36 of relay 'CTPR is closed, it 'establishes'a directponnection between the grid 22a and cathodeV 20a of tube VA, and when 'front contact 38 of relay YCTPR is closed, it establishes a direct connection between the grid 22h and cathode 20b' of' tube As a result, the bias potential between the grid `and cathode of each tube vis reduced "to zero, rand lthe tubes will fire, tube VA firing during the half cycle of the alternating current when'terminal CX is positive with respect to terminal BX, and tube VBliring during the other half cycle ofthe alternating current when terminal BX is positive with V'respect to terminal CX. The primary winding 4U of transformer rTTis connected across the terminals BX and CX of the source of `alternating current through the tubes VA and VB in parallel so that energy from the `source is supplied to 'the transformer primary winding through', the 'tubes from the source when the tubes are conducting. Energy supplied 4to the primary winding of' transformer TT induces alternating 'current in the transformer secondary winding 42. This alternating current is rectified by the full-Wave rectiiier TRX, and the resulting direct current energy is fed to the exit end of track section T in a manner tobe subsequently described.

When the contacts 36 and 38 of relay CTPR release, the bias voltage is again supplied to the grids of tubes VA and VB, and if the alternating current is near the end of a half cycle at the time, the tubes will stop conducting at once. If the bias voltage is supplied during the conducting portion of a half cycle, when the current is high, the tube which is to pass current will continue ring until the end of that half cycle, and will then be extinguished.

The limiting impedance R3 serves to limit to a safe value the flow of current through the tubes VA and VB and the current in the secondary circuit including rectifier TRX, While the tubes are conducting and track section T is occupied by a train.

The condenser Ca and resistor Ra in the grid circuit of tube VA serve to provide a small direct current bias component on the grid 22a of tube VA when tube VA is not ring. When the grid 22a of tube VA has a positive potential, a small amount of grid current will iioW between the grid 22a of tube VA and the cathode 20ct. This flow of current through the resistor Ra causes a voltage drop across the resistor, and as a result the condenser Ca is charged. At this time the flow of current through resistor Ru will be from left to right, with the result that the element of condenser Ca which is connected to the grid 22a of tube VA will have a negative potential With respect to the other element of the condenser. When the grid 22a of tube VA changes polarity the negative charge of the condenser Ca establishes a direct current negative bias on the grid, since the negative potential is on the element of the condenser which is connected to the grid of the tube. The direct current negative bias thus supplied to the grid of tube VA serves to prevent false firing of the tube due to transient surges in the supply of alternating current to the apparatus.

Condenser Cb and resistor Rb in the grid circuit of tube VB function in a similar manner to that described above for condenser Ca and resistor Ra and a detailed explanation of their operation is unnecessary.

If the supply of alternating current to the transformer PT be interrupted for any reason, the supply of energy from secondary Winding 26 of transformer PT to the heaters 2| of tubes VA and VB and to the Winding of relay TER Will be cut off. As a result, front contact 28 0f relay TER will release and therebyinterrupt the supply of energy to the anode-cathode circuits of tubes VA and VB, to thereby prevent the supply of energy through the tubes while the heaters in the tubes are not properly heated.

When the supply of alternating current energy is restored to transformer PT, the secondary winding 26 again supplies energy to the heaters 2| of tubes VA and VB. However, the anodecathode circuits of tubes VI and V2 remains interrupted by front contact 28 of relay TER until a certain time has elapsed after energy is again supplied to the relay winding, for example, 30 seconds. During this time the heaters will have raised the temperature ofthe cathodes to their operating point. After this time interval has elapsed, front contact 28 of relay TER picks up and thereafter remains picked up, thereby restoring the supply of energy to the anode-cathode cir-g, cuits of tubes VA and VB. The characteristics of the type of tubes used in this arrangement are such that if energy is supplied to the anode-cathode circuit of a tube before the cathode of the tube is suiiiciently hot, deleterious results may occur, and it is necessary therefore to provide some type of time delay between the supply of energy to the heaters of the tubes and the supply of energy to their anode-cathode circuits.

It is to be understood that various other means of obtaining the time delay may be used in connection with this invention, the means shown herewith being one type which may be used.

From the foregoing it will be seen that each time the contacts of relay CTPR pick up, the bias is removed from the grids of the tubes VA and VB and they will then re during alternate half cycles of the alternating current supplied to them, and when the contacts of relay CTPR release, the bias is restored to the grids of the tubes so that they stop ring. Accordingly, the contacts of relay CTPR have only to interrupt the grid bias energy, While the thyratron tubes interrupt the heavier load of the energy supplied to the transformer TT.

The equipment is shown in the drawings in its normal condition, with track section T unoccupied. Code transmitters IBUCT and 'l'.iCT operate continuously, the contacts of code transmitter IBdCT being operated at a frequency of 180 complete cycles per minute, While the contacts of code transmitter TSCT are operated at afrequency of 75 complete cycles per minute. As shown, the control relay CR, which may be controlled in any suitable manner by traffic conditions in advance of section T, is picked up, and when the contacts of code transmitter ICT pick up, a circuit is established to supply energy to the relay CTPR. This circuit is traced from terminal B, over front contact I0 of code transmitter l88CT, front contact I2 of relay CR, and through the winding of relay CTPR to terminal C.

When the contacts of relay CTPR pick up, its contact I4 establishes a circuit to supply energy to the Winding of relay CTPPR. Accordingly, at this time, when contact I0 of code transmitter l 80CT picks up, relayCTPR picks up and shortly thereafter relay CTPPR picks up. Similarly, each time contact l of code transmitter ISUCT releases, the contacts of relay CTPR release and interrupt the circuit of relay CTPPR, and shortly thereafter the contacts of relay CTPPR release.

When relay CTPR picks up to close its contacts 36 and 38 in the circuits of the grids of tubes VA and VB, contact 50 in the circuit for supplying energy from the rectiiier TRX to the track rails is closed. The contacts 36, 38 and 58 operate substantially in synchronism and will close at or substantially at the same time so the circuit for supplying energy from the rectifier TRX to the track rails is closed at the time the tubes VA and VB become effective to supply energy to the circuit of the rectier TRX. When contact 59 of relay CTPR picks up it opens the circuit of relay AR, while when contact I4 of relay CTPR closes energy is supplied to relay CTPPR and its contacts pick up with the result that contact 48 of relay CTPPR establishes a connection shunting contact 50 of relay CTPR, and contact 58 additionally interrupts the circuit of relay AR.

As previously explained, when the contacts 36 and 38 of relay CTPR pick up, the thyratron tubes VA and VB lire, and energy is supplied to the rec- A 7 tier TRXfrom @the secondary'Wind-inglZ .of transormer'T'I". The vresulting direct current energy is Asupplied to' the trac/llt Irelay TR at the entrance Y'end 4of the section T by a circuit `Vwhich is traced from the positive terminal-of the rectithrough section rail |,vthrough Athe winding vofV tact -52 establishes a connection 'from terminal B of the r'source to :the left-*hand terminal of the -primarywinding A513 .of ltransformerIT. vThe .center "terminal of this VWinding is .connected 'itc 'termina'l lCJ-fof 'the source so' that `onehalf of 4'the vtr'zainsfornier winding is energized `and an 'impulse of-'energylisinduced in-the transformer secondary Winding 56, and -is `supplied therefrom to -the winding Vlof relay 21R. However, relay IR is of a tylpe vthe :contacts of which become :picked up only when energy of one polarity is Ysupplied. to the winding and the V-vari'ous lparts of Vthe equipment are arranged -so that lthe energy supplied tofthe relay on movement of the contacts of relay to `their picked-up positions fisof jsuch polarity -as to lhe ineective ltopick up the con tacts of relay V-nft'e'r-abrie'f Itimeinterval, contact -l of code `transmitter lSCTopens, 4ther-elly interrupting conducting lAccordingly,.Wlfiencontact -offreayfCTPRreleases, the circuitI for supplying energgyfrom Tectier TRX ltothe :section rails l and Tis-maintained by contact 348 of relay OTHER, 'sotha'tthe 'cur-rent flowing inthe :circuit -is4 not interrupted ny the contact-"50 of :relay CTPR. o

lvshencontactsfand t3y o'f relay CT-PR-frelease, "the biasis restored Ito the v'grids of .tubesfVA :and 37E-as exnlainedabove, 'and vthe tubesstcp iring "within a"halfcyc1eof the -alternatingcurrent supply'. risaV result, thefenergysupplied sto recti- ,b

ner'rmiffromthertransformer' 'rr isinterrupted, and Sthe `supply-j of direct current :energy from the rect'ier TRXtothei'track ralls'is cutoff.

Shortly thereafter,the'contacts"of-relay CTPPR frelea'se, thel supply 'lof energy Lto the :winding v of TlaTCTPPR-'having heen interruptedlby the -re- 'leaserof contactloff-relay v(1T-PRIt Since the supfply -of energy *fro-rn 'rectifier TR'Kis interrupted tothe `'se ation rails has alreac'lyv been vinterrupted wh'enffront lcontactt of `relay CTP-PR-opens, "and as a consequence; the contact i3 is not refquired to openthecireuitunder load.

v"When the Vcontacts fof "relay 'C'I-PRV and rela-y x'IPflt Yare 4released the `approach vrelay AR fis connected `-across the `section` rails l i fand $.21.by :a clrcit 1 including Vback contactii.. 0f "relayCTPR eadv back 7cont-"a, et-158..;ofrrelay CTPPR the vinterruption@of rather-supply.. frener'gy from rectifier TRX, .the contacts ofrelay rer* lase-and contact f52 thereupon establishes a 'cire cuit to yenergize :the righthand portion .of 4the primary lwinding 54 lof transformer IT. As a re: suit, an impulseoenergy is induced in .the former secondary Winding 5.8 and this m1111158 is of a polarity opposite fto thatrof theimpulsi@'--DIQS- ent on movement Aof the contacts vof relay to 'ftheir pickedfnp positions. Accordingly, :the energy/'supplied to vthe VWinding of relay is effective to :momentarily lpick up the contact of this relay.

:On :pick-ing upcf Yrelay its contact 4,6 inter.: rupts the .circuit traced alcove or connecting the winding of the relay TR across .the track rails andV establishes a :circuit -#to supply ,energy `from the matt-ery iB ALover fthe vsection rails i and 2 Vto the winding-.of relay This circuitis traced fromfthefpositivefterrninal of =loatterylB over from Contact ist of .relay 1R, through itheAsection-rail over back contact 5B of relay CTPR, through'gthe Awinding of relay ARefrornleft to right, over back Contact t8 fof relay @iT-PPR, 4and through Wire 4.4 and section rail E! ftoithe-negative'terminal ci bat-r tery fB. Thepolarity of gthe energy supplied Eto relay AR issuch that -it is eective @to pick-up the gcontacts -of ithe relay AR.

-After a brief ltime interval the :relay fIRJreleases and its :contact et interrupts "the supply :of envergy :from Athe hatterylB t@ ,the @relay AR. and reconnects thetrack relay TR, :across the section rails A and 2.Y

Silbsequently, contact 19 4of code transmitter LEQT closes, and again supplies energy .to relay QTBR'which picks Yup.andzthel-cloy :interrupts the circuit connecting relay AR to the section rail-.s and ,again establishes ithe circuit -fcr ring fthe .rhyratrcns SEA-and .VBin `additiongto,-estabclshins thefcircut; iorzccnnectnethe,rectifier TRX tothe section rails andthe circuit for energizing relay '.ClPP. f sA-.longzas the -trackfozseeton iSv-acant, the scellement ycorltirme to ener, e @in this financer. :Energyiis jspinali@datoV thetrackrrelay Overathe I-railsqof section rectier'FRX ,l80;tim,es per minute, and during the olf internals `rgy is-supp1iedreverrthe-fstion rails to the -relayR f from battery telar R Ahas associated therewith a code :def testerrelay.HRrwhichiSenersized by currents@- plied through a decoding transfprrnersDfl and Qmyfwhen theftrfa-ckrrelay fellows @aderiranlai'ned inu.illetiers??afent.ofrtllev CJI ce wffSHfCent-lalue toipick up the relay contacts #wasmand Qniyavhenenergr is ,Supplied tothe decoding unit at .afnemer-lericiflcylesgper'minlrte from ,deco v,nel.trans.foncer` DT.

f Atths ktime theffconteets effrelafy arecper- :ated 1:80 timesrerlminute'-inrresponse to theV lmp, ses of -energysupmied from thezexitendof s .tion fandaszafresult the; Contacts @Helaas H -fand^DR arapicked up,-,;and- .thegreen lamp G (of signal eS fis supplied with cheres/,at-,ths time n., @by Athe obvious-circuitincluding front-contactar@ eef; relayfI-llk and front tcontactg'l t off relay DR.

Approachfr-e1ayfARilOcated fat the exit lender section TfhasrSSOoiated therewith aan arpffnroachi-repeatenrelayrABR which issuer/size by f, .cerrentlsupplied ,threnghladeeediaeetransfonner lagain feed to track and impulses of 49 AT when and only when the relay AR follows coded energy, as explained above in connection with relay HR. The contacts of relay AR are operated at this time by impulses of feed back energy from the battery IB, and accordingly, the contact 12 of relay APR is picked up, showing that section T is unoccupied.

It will now be assumed that a train moving from left to right passes signal S and enters section T. The wheels and axles of the train shunt the impulses of master code energy from the winding of relay TR, and its contacts release and remain released. As a result, energy is no longer supplied to the windings of relays HR and DR, and these relays release, interrupting the supply of energy to the green lamp G and establishing an obvious circuit for supplying energy to the `red lamp R of signal S.

Additionally, contact 46 of impulse relay IR remains released so that impulses of feed back energy are no longery supplied to track section T from the feed back battery IB, and as a result the contacts of relay AR remain released. Accordingly, relay APR is no longer supplied with energy from transformer AT, and its contact 12 releases, to thereby indicate the occupancy of section T.

During occupancy of section T the equipment at the exit end of the section continues to operate as explained above to supply impulses of energy through the rectifier TRX to the track rails. Because of the shunting effect of the train the value ofthe impulses supplied to the rails increases as the train approaches the exit end 'of the section. However, as explained above, the supply of energy to the track rails is always interrupted by the tubes VA and VB and not by the contacts of relays CTPR and CTPPR. Accordingly, even though the section is occupied for a considerable period, the contacts of relays CTPR and CTPPR will not be damaged, as might be the case if the contacts of these relays were required to interrupt the supply of energy to the track rails.

When the train under consideration enters the section in advance of section T, the relay CR releases and transfers control of relay CTPR from the code-transmitter IBDCT to the code transmitter TECT. Except for the change in the rate of operation of the relays CTPR and CTPPR the equipment operates as described above.

When the train vacates section T, impulses of master code energy supplied to the track rails relay TR, and as a result of contacts, energy is again supplied through transformer DT to relay HR, and its contacts pick up. trol relay CR is released, and its back contact l2 establishes the circuit including contact 14 of code transmitter 'I5CT for supplying energy to the winding of relay CTPR. Accordingly, the relay CTPR operates its contacts 75 times per minute, master code energy are supplied at this rate to track relay TR through section rails l and 2. The operation of the contacts of relay TR supplies energy to relay HR through the decoding transformer DT, and the contacts of "relay HR pick up, but since the frequency of the energy now supplied from transformer DT is 75 cycles per minute, relay DR is not supplied with `suiiicient energy to pickup its contacts, and its contacts remain released. When relay'HR picks up a circuit is established over its front contact `68 and back contact 10 of relay DR to supply energy to the yellow lamp Y of signal S.

Additionally, each time contact 52 of track relay TR releases, relay IR picks up momentarily At this time, however, conto supply an impulse of feed back energy from the feed back battery IB to relay AR through section rails I and 2 and over back contact 5U of relay CTPR and back contact 58 of relay CTPPR. The code following operation of relay AR supplies energy to relay APR through the decoding transformer AT and the contact 12 of relay APR picks up to show that section T is unoccupied.

As the train under consideration progresses farther, the contacts of relay CR pick up, and its front contact l2 establishes the circuit for controlling relay CTPR over contact lil of code transmitter IBUCT. As a result, the contacts of relays CTPR and CTPPR operate 180 times per minute, and impulses of master code energyare supplied to track relay TR over section rails I and 2 at this rate. The contacts of track relay TR now operate 180 times per minute, and as a result the energy supplied to relay DR from decoding unit |DU is of a value sufficient to pick up the contacts of the relay. When contact 'l0 of relay DR picks up, it cooperates with contact 68 of relay HR to establish the circuit for supplying energy to the green lamp G of signal S.

Additionally, relay IR operates times per minute to supply impulses of feed back energy from the feed back battery IB to the relay AR, and as a result relay APR remains energized.

The equipment is now restored to its normal condition as originally described.

In Fig. 2 there is shown a fragmentary View of a modification of the equipment shown in Fig. 1, wherein the windingof relay CTPPR is directly connected across the output terminals of the rectifer TRX, so that as long as energy is supplied through rectier TRX, relay CTPPR will be picked up. The remainder of the apparatus is arranged in a manner similar to that shown in Fig. 1.

In operation, when relay CTPR picks up, its contact 5!! establishes the circuit for supplying energy from the rectifier TRX to the track rails l and 2 of section T and interrupts the circuit for connecting the winding of relay AR across the rails of section T. When contacts 36 and 38 of relay CTPR pick up, the tubes VA and VB are rendered conducting, as explained in detail in connection with Fig. 1. As a result, energy is supplied through the rectifier TRX to the track rails i and 2 of section T, and additionally to the winding of relay CTPPR. When contact 48 of relay CTPPR picks up, it establishes a circuit in multiple with front contact 5S of relay CTPR for supplying energy to the rails of section T, and when contact 53 of relay CTPPR picks up, it additionally interrupts the circuit of the winding of relay AR.

When relay CTPR releases, its contact 50 interrupts the connection previously established for supplying energy from the rectifier TRX to the rails of section T, but the additional connection established by contact 48 of relay CTPPR is maintained at this time, so that contact 50 is not required to interrupt the flow of energy. When contact 59 of relay CTPR releases, it again estab- .lishes one portion of the circuit for connecting relay AR across the rails of section T, but this circuit remains interrupted at this time by contact 58 of relay CTPPR. When contacts 36 and 38 of relay C'I'PR release, the tubes VA and VB are rendered non-conducting and accordingly, the supply of energy through the rectier TRX to the rails of section T and to the winding of relay CTPPR is cut off. Whenv relay CTPPR releases, its contact 48 interrupts the circuit for connecting aucunes Y -11 the rectiiier TRX to the section rails, and contact 580iV relay CFIPPR completes the circuit for connecting the winding of relay AR across the section rails. The recurrent operation of the contacts of relay VC'IPlft causeV a repetition of the cycle described above. Accordingly, it will be seen that each time relay CTPR picks up, the winding of relay AR is disconnected from the rails of section T, and energy is supplied to the rails of section T from rectifier TRX as a result of tubes VA and VB being rendered conductive bythe picking up of the contacts o f relay CTPR. When energy is supplied from rectifier the relay picks up, and front contact 48- of relay CTPPR establishes an additional circuitior connecting section T to provide an alternating current'coded. track circuit system, or ahalf-wave rectiiier may be substituted for the full-wave rectifier TRX to provide pulsating direct current energy for track section T.

Although there are herein shown and described only two forms of coded signaling apparatus embodying this invention, it is understood that varithe rectifier TRX across the rails of section T,

while back contact 53 of relay CTPPR additionally interrupts the circuit for connecting relay AR across the section rails. When relay CTE/R releases', its contact 50 interrupts one circuit for supplying energy to the rails of section T from the rectifier but front contact 43 maintains its circuit, so that the supply of energy is not interrupted by contact 59 of relay CTPR. When contacts '36 vand 3;2 of relay CTPR release, the tubes V'A and VB become non-conductive and as a resuit,4 energy is no longer supplied to the rails of VSection "I and the winding of relay CTPPR, and

relay CTPPR releases, thereby interrupting the connection from the rectifier TRX to the vtrack railisgand' connecting the relay AR to the rails.

'Since relay QTEPR releases when and only when the supply of energy through the rectiiier ceases, it-

clear that Contact 48 of relay CITPER is not required to 096,11. the circuit of the rectifier while energy is being supplied through the rectifier;

An advantage of the arrangement shown in Fig; 2V is that if `by some derangement orV failure, the tubes VA and, VB continuously conduct, the relay CTPPR will obviously be continuously energized', and thereby cause a continuous supply of energy to the rails of Vsection T. In a system such as that shownin the drawings, the continuous supply of energy to the cooleV following track relay will cause the signal to display its stop aspect, and thereby indicate improper operation vof the equipment.v

Additionally,v since-relay CTPPR would be continuously energized under Ysuch circumstances, contact 5i! of relayI CTER: would not be required to make and break the circuit for supplying energy to the rails of section T, so that the contact would not b e subject to arcingand other adverse effects. Also, contact of'relay CTPPR would continuously interrupt the circuit for connecting relay AR'to the section rails, and as a result, relay APB, would release and remain released, to also `indicate improper operation of the equipment.,

It will be seen from the foregoing that the arrangement of apparatus comprising this invention is such that large amounts of power may be supplied to a coded type of signaling system withiiut adverse effects on the contacts of the controlling relays. It will be apparent to those .skilled in the art that the arrangement of appara-tus is not limited to4 that shown, but may be applied- Vto various types of coded signaling systems, for example, in the arrangement shown 'in' Fig. l, the feed backgbattery IB maybe replaced by an arrangement similar to that shown Y forsupplyingV master code energy- Also, the recltier TEX may be omittedl andthe alternating Qcurrent energy supplied from the secondaryy 4 2 f of transformer TT may bev'supplied to the track cus changes and modiiications may be made therein within the scope of the appended-claims without departing vfrom the vspirit and scope of this invention.

Having thus described our inventiomwhat We claim is:

Vl. In a coded signaling system, a'pair of con ductors, a first transmitting Vrelay having con tacts `recurrently operated between va rstand a second position, a second transmitting relayfhaving contacts which are operated to a first or a second .position according as the contacts of said first transmitting relay are in their'rst or their second position, a transformer, circuit means for connecting said conductors to the terminals of thesecondary winding of said transformer whenv the contacts of at least one of said transmitting relays are in their second position, means for connecting the primary winding of said trans- -former to a source of alternating current in se- ,relay .occupyl .their second Yposition- 2. In a coded track circuit signaling system, a section of railway track, a riirst transmitting relay having contacts operated between a first and a second position at a selected code rate, a second transmitting relay having contacts Ywhich are operated to a iirst or a second position `according as the contacts of saidV first transmitting relayA are in their first or their second Apor s ition, av track transformer, circuit means Vfor connecting the rails of said section withA the terminals of; the` secondary windingo f, said track transformer whenV the contactsrofat; least one oi' said, transmitting relays are in. their second position, means for connecting the primary winding of said. track transformer with a source of, alternati-ng current in series with a first elect-l10n tube capable oi permitting. W of energy oftnormal polari-tr and a second electron.- tubc capable Vof permitting flow `of energy of reverse polarity.

and control.. means for each of--saidtubes governed by a contactfof said first transitiitterl re.- lay and arranged to causev said tubes tobez conducting when and only when` the, contacts of said rst transmitter relay occupy their second position, and a circuit including a iirst position contact. of said iirst transmitting relay and a iirst position contact of said seco-nd transmitting relay connected iny series for coune,citing thev rails ot said section to. the winding of a. c0de=fo11ow ing relay. v

3.. In a. coded track circuit-Signaling system, in combination, a, section cie railway 'trackJv a iirst transmitting relay haring, contacts operable between a. first and. a Second-position at a selettori Code rata a Second transmitting; relay having contacts which are, moved. ma rstwor ing the rails of said section to a source of energy when the contacts of at least one of said transmitting relays are in their second position, said source comprising a source ofA alternating current, a pair of electron tubes, a transformer having a primary winding connected in series with said tubes and said source, control means for each of said tubes governed by a contact of said iirst transmitting relay and arranged to cause said tubes to be conducting when and only when the contacts of said first transmitting relay occupy their second position, said second transmitting relay being constructed and arranged so that the time required for the contacts of the relay to operate from their second to their rst position is longer than one half of a complete cycle of said alternating current source.

4. In a coded track circuit signaling system, in combination, a section of railway track, a iirst transmitting relay having contacts operable between a iirst and a second position at a selected code rate, a second transmitting relay having contacts which are moved to a first or a second position according as the contacts of said first transmitting relay are in their rst or their second position, circuit means for connecting the rails of said section to a source of energy when the contacts of at least one of said transmitting relays are in their second position, said source comprising a source of alternating current, a pair of electron tubes, a transformer having a primary winding connected in series with said tubes and said source, control means for each of said tubes governed by a contact of said first transmitter relay and arranged to cause said tubes to be conducting when and only when the contacts of said nrst transmitter relay occupy their second position, said second transmitting relay being constructed and arranged so that the time a required for the contacts of the relay to operate from their second to their first position is longer than one half of a complete cycle of said alternating current source, and a circuit including a first position contact of said first transmitting relay and a first position contact of said second transmitting relay connected in series for connecting the rails of said section to the Winding of a code following relay.

5. In a coded track circuit signaling system, in combination, a section of railway track, a rst transmitting relay having contacts operable between a first and a second position at a selected code rate, a second transmitting relay having contacts which are moved to a first or a second position according as the contacts of said first transmitting relay are in their iirst or their second position, circuit means for connecting the rails of said section to a source of energy when the contacts of at least one of said transmitting relays are in their second position, said source comprising a source oi alternating current, a pair of electron tubes, and control means for each of said tubes governed by a contact of said rst transmitter relay and arranged to cause said tubes to be conducting when and only when the contacts of said first transmitter relay occupy their second position.

6. In a coded track circuit signaling system,

, in combination, a section of railway track, a first transmitting relay having contacts operable between a rst and a second position at a selected code rate, a second transmitting relay having contacts which are moved to afirst or a second position according as the contacts of said first transmitting relay are in their first or their second position, circuit means for connecting the rails of said section to a source of energy when the contacts of at least one of said transmitting relays are in their second position, said source comprising a source of alternating current, a pair oi electron tubes, and control means for each of said tubes governed by a contact of said first transmitter relay and arranged to cause said tubes to be conducting when and only when t-he contacts of said rst transmitter relay occupy their second position and a circuit including a first position contact of said first transmitting relay and a rst position contact of said second transmitting relay connected in series for connecting the rails of said section to the Windin of a code following relay.

7. In a coded track circuit signaling system. a section of railway track, a rst transmitting relay having contacts operated between a first and a second position at a selected rate, a second transmitting relay, means effective when the contacts oi said rst transmitting relay are moved to their second position to move the contacts of said second transmitter relay to their second position, means effective when the contacts of said nrst transmitting relay are moved to their first positions to move the contacts of said second transmitting relay to their irst position after a predetermined time interval, a source of alternating current, a pair of electron tubes, control means for rendering said tubes conducting when the contacts of said rst transmitting relay are in their second position, and a circuit over which energy may be supplied from said source through said tubes to the rails of said section of track when the contacts of at least one of said transmitting relays are in their second position.

8. In a coded signaling system, a pair of conduct-ors, a first and a second transmitting relay each having contacts movable between a first and a second position, means for recurrently moving the contacts of said iirst transmitting relay between their rst and their second position, a source of alternating current, a pair of electron tubes, control means for rendering said tubes conducting when the contacts of said first transmitting relay are in their second position, a circuit established when the contacts of at least one of said transmitting relays are in their second position and over which energy of one polarity may be supplied from said source through one of said tubes to said conductors and over which energy of the other polarity may be supplied from said source through the other oi said tubes to said conductors, means operative when the contacts of said iirst transmitting relays are moved to their second position for moving the contacts of said second transmitting rela-y to their second position, and means operative when the contacts of said iirst transmitting relay are moved to their rst position for causing the contacts of said second transmitting relay to move to their first position only after energy has ceased to be supplied from said source to said conductors, whereby the circuits for supplying energy from said source through said tubes to said conductors are not interrupted until after energy ceases to be supplied through said tubes.

9. In a coded signaling system, a pair of conductors, a rst transmitting relay having contacts recurrently operated between a rst and a second position, a transformer having a primary and a secondary winding, a vsecond transmitting relay having a winding effectively connected across the 15 secondarywindngfof said transformer and hav- K.Cioni'iacts which are biased to a iirstrposition and A'are ,moyed to a .second position whenenergy :supplied to said relay winding, circuit means for -connecting said conductors to the terminals v@fthe secondary winding ofsaid transformer 4when thecontacts lof at least one of said trans- 1nnitting relays arefin their second position,.means fior connecting the primary winding ofsaid .transjormer toa-source of alternating current in series fwithfa .fi-rst electron tube capable of permitting #flown-f energy Lof one polarity and also in series iwi-thea, second ,electron tube .capable .of vpermit l...tix-ig ,flow of energy ,of the other polarity, and ,control means .for each .of said vtubes governed .-byajoontact of .said .first transmitter -relay and arranged to cause said tubes .to be conducting when zand only when the contacts .of said first `:transmitter relay cccupytheir second position.

, 510. In a-coded signalingsystem, a pair of con- :fd-uctors, ,a yfirst transmitting relay having :con-

tacts recurrently operated between a first and a ifsecond position, a transformer having a primary vranda secondarywinding a second transmitting rela-y vhaving -a winding effectively connected yacross the .secondary winding of said transformer land having contacts which are biased to a rst yposition andiarefmoved to a vsecond position when nergy is supplied 'to said relay winding, circuit -means for connectinggsaid conductors -to the Vterminals `ofthe secondary winding of said trans- ":crmer when the contacts of atleast one of said ,ftransmitting relays are in their second position, `:means for rconnecting the primary winding of ffsaid transformer to .a-,sourcefof alternating curfrent in series with a first electron tube capable of permitting flow of energy of one polarity and also in series with a second electron tube capable of Vpermitting flow of energy ofthe other polarity, control means for each of said tubes governed *by a contact of said rst transmitter rel-ay and `-zarranged to cause said tubes to be rconducting A4ivhenrand only when the contacts of said -first "transmitting relay occupy their second position, 1 and a vcircuitlincluding a `rst position contact of Vsaid first transmitting'relay and a first position contact of said second code transmitting relay `connected inseries for Yconnecting said -conducftorsto'the winding of a code following relay.

1d; Ina Vcode transmitting and receiving means -for a lcoded signaling system, in combination, Aa vrpa-'ir of conductors, an electron tube, a pair of ysup- .plywires over which energy may be supplied from la source of alternating current through said tube to isaidconductors, ya first transmitter relay 'having oontactsrecurrently operated between a rst and a second position, `a second transmitter re- F'lay 'having contacts biased to a released position y*fron-1' which they are movable toa picked up position on the supply of energy to the relay windnection between said supplywires and Vsaid confductors and Yto render said tube conducting, 'and "0 @means ,for rendering said tube non-conducting.

.12. In .code .transmitting and receiving means `.for acoded `signaling system, in combination, a pair of conductors, a transformer, a pair of Isupply wires .over which energy maybe supplied from the secondary winding of said .transformer to .said conductors, a r'st transmitter relay having contacts .recurrently operated between a first Aand a second position, a second transmitter relay `having contacts movable between a first and .asecond position, means for .establishing `connection from said ,supply wires to said conductors when .the contacts of either of said transmitter .relays l.are .in their second position, circuit means effective .on -movement of the contacts of .said .first transmitter relay to their second position to establish l.a circuit over which energy maybe .supplied .froma source of alternating current to the primary winding of said transformer, and `-means for `controlling said second transmitter relay so as to v4causeits contacts to move from their first to .their second position before the vcontacts .of,.said rst transmitter relay move from their second to .their nrst position and so as to cause the contacts of said second transmitter relay to move .from their second to their flrst position only after the contacts of said first transmitter relay move to their first position.

13. In code transmitting and receiving means yfor acoded signaling system, in combination, .a pair .of conductorsa transformer, a first trans- .mitter relay having contacts recurrently foperated between a first anda second position, va .second transmitter relay having contacts mova- ,ble between a first-.and va second position, circ-uit mea-ns governed by .a contact of said iirst transmitter relay for .at times establishing a `circuit over which energy .may be supplied from a source of alternating current to the primary winding of said transformer and Yfor -at other times interrupting said circuit, a circuit including a contact of said second transmitter relay for connecting the secondaryvwinding of said transformer across said conductors, a code following relay having a winding which at times is effectively connected across said conductors by a circuit governed by a .contact of said second transmitter relay,and means for controlling said second transmitter relay so that its contacts maintain the circuit for connecting the secondary winding of said transformer across said conductors until after the supply of energy to the primary winding vof said transformer has been interrupted and so that the winding Yof said code following relay is elfectively connected across said conductors only when the circuit for connecting the secondary winding of ,said transformer across said con `ductors is interrupted.

CLARE OHAGAN., Administrati of the Estate of Bernard E. 0 OHagan, vDeceased PAUL N. MARTIN.

REFERENCES CITED The following .references are of record in the 5 file of this patent:

UNITED STATES PATENTS Number Name Date 1,691,423 Alexandersonet a1. Nov. 1'3, 1928 1,723,858 Hull Aug. 6, -1929 '2,285,891 Blosser June V9,1942

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