US2482296A - Railway signaling apparatus - Google Patents

Description

Sept. 20, 1949. c. B. SHIELDS RAILWAY SIGNALING APPARATUS Filed Dec. 11, 1946 emB. Sb z'elair:

INVENTOR.

HlSATTvHA EK Patented Sept. 20, 1949 RAILWAY SIGNALING nrrnnn'rus Charles B. Shields, Penn Township, Allegheny County, Pa., assignor to The Union Switch 8: Signal Company, .Swissvale, Pa., a corporation of Pennsylvania Application December 11, 1945, Serial Nc.

9 Claims.

My invention relates -to railwaysignaling apparatus and par-ticularlyto "the organization of such apparatus into coded track circuit systems of railway signaling incorporating approach control m a s- =Coded track circuit systems of railway signaling have been proposed in order to obtain the improved shunting characteristics and protection against broken rails 'and foreign current that coded track circuits afford in comparison with themsualsteadily energized trackcircuits. Additional-advantages are-obtained from the use of coded track circuits by employing a plurality of code rates ito provide a plurality of channels for communication through the track rails, thereby making it-unnecessaryto useline' wires extending betweenthe-ends of atrack'section, and by employing coded alternating current in the track rails which enables controlto be established over eitherorboth train carried apparatus and wayside equipment.

In thesesystems maximum advantage is obtained from the use of coded track circuits by applying the coded track circuit energy to the exit'end-of each-track-section for transmission through thetrackrailsto the entrance end where it is used -t operate decoding apparatus at that end. '-Ihe decoding apparatus is'utili'zed for the control-ofwaysidesignalsandfor the control of the tracl; circuit energy that is applied to the section in the rear. Entrance of a train into a section 'therefore causes a "Cont/r0110 be estab- -lished-at%the entrance end of the section by means whichutilize the'track rails as' transmission conductors andma-keunnecessary the useof control line wires.

In many casesit is necessary to have traffic in a section establish acontrol at apoint in advance of the-entering end of'thesection. This is particularlytrue, for-example, inthe case of a-highway crossing signal located at a gradeintersection intermediate the ends'of a-section. Operation of such a signalmust be initiatedwhen the train enters-the-control section for the signal and must :be terminatedwhen -'the train clears the intersection. In coded track circuit systems where-cab signaling is" involvedit-is necessary to detect -'the unoccupied condition of the control section by means of track circuit energywhich will not 'cause'operation-of the cabsignals, and insuch cases it 'has been customary tofuse stead-y or non coded direct 'current for detecting We clearing of the control' section.

It-isan object of myinvention to'provide'novel and improved means for detecting the clearing 2 of a control section fora-highway crossing signal in a coded track' circuit system-of railway signalmg.

Another object is to provide novel and improved means for" utilizing coded track circuit current for detecting the 'clear-ing of a control section for a --highway cr6ssing signal in a stretch of track-provided with a coded track circuit system of-railway-s-i'gnalingl Another objct ojf' iny -i-nvention is to provide novel "and =improved meahsfior utilizing coded direct "cui' rentFin atom-p1 section for a highway crossing 's'ignal a' coded tracli-cirouitsystem of railWay-signalnigj-ahd for' apjplyi'ng coded alternating-current' 'to tion-whnrequired for controlling cabs;

Another object"}is"{to p p, proved means' for con-troll g' a -highway crossing signal in 'a coddtrack ntuit-system of railway Signaling,

In accordance with my invention the control section for a highway cros ng'signal is normally supplied with eeaea -traek c c'uit current of the clearing-out typefandth wayside equipment at the entering eh'd --or1t e section as w n as the highway crossing Sign -at'-the inter'section are controlled by greats-cf aline' circuit incorporating contacts at the ends some circuit synchronously-operated tfo provide-two control channels for respectively controlling apparatus at the entering m'and'appsi-au's at the intersection. The line-wire i: ll" ppar'atus at the intersection also pro'i means-for applying coded alternating cur-rent gto the'control section during the intervarthat atra-iri approacheslthe intersection in the control section.

I shall d marine-farm of apparatus embodying-my ihvefitionfa'ndshall then point out the novelfeaturesthere ft lhe gcoripshygfig dmw g is a diagrammatic view ofa'preir v apparatus embodying m e l 6..

'Referr-in'g to the drawing, the reference characters -l and- -l"gifdesi' the track rails of a stretchf failway tra whichtraffic equipped with train carried" gnaling gr control facilities operates in the'fdiiiectin'fi 'd'icatedby' an arrow, or from icftto rightas wed n*the"drawing. Therails l and l iiaridi lded' ineansof insulatedj oints'fi to a tract: sec rod-cgahnatm q i l fih ii fifi ji ifi 'ile u -setion locati n it 'an advanc trance end 3 of section 3-4 for governing railway.

trafiic in the section. Signal 3S may take any suitable form and is shown, for example, as acol-' or light signal comprising a green lamp G, a, yellow lamp Y and a red lamp R efiective when energized to indicate clear, cautionand stop, respectively.

The section of track 34 is,provided with a 4 extending from one terminal B of a suitable source of current, such as a battery not shown, through front contact I5 of relay ATR, front contact I6 of relay ACDR, and the winding of relay CTM to the other terminal C of the source of cur rent, and relay CTM therefore normally is energized and deenergized incstep with the energized and deenergized conditions of relay 'ATR. Whenever relay ATR ceases to follow code and relay 'ACDR releases, relay CTM is then energized over a, circuit including back contact I6 of relay ACDR 'and'contact Hi-of the code generator 150T. Re

layCTM has associated therewith a track battery signaling system of the coded track circuit type comprising code transmitting means atexit end 4 of the section, code repeating and control means 5 at location 3a, and decoding and control means at the entrance end 3 .of the section. p I

The code transmitting means at section end A include a track transformerllTT, code generators I5CT and I8IlCT and a selecting relay HR The code generating means-150T and I8I1CT constitute continuously energizeddevices which operate contacts I5 and. I80 alternately into and out of circuit completing positions at the rate of,

forexample, 75 andlBO- times per minute,- respectively. The track transformer ITT has its secondary Winding I I] connected across track rails l andyla adj acentto exit end 4 of the section and has its primary winding I I supplied, from a suitable source conventionallyindicated in the drawcing'by the terminals BX and CK, with alternating currentperiodically interrupted or coded by contact I5 or I of coding device 150T or IBQCT, with the'selectionbetween the contacts I5 and I80 being established according as relay HR is released or picked up, respectively. Relay is responsive to traffic in the stretch in advance of section 3 4 and may be controlled bysuch trafhe in amanner similar, 'for example, to th control shown for relay A CDR and described hereinafter. j The code transmitting means at exit end 4 of the section accordingly operates to supply coded alternating current at the 180 code rate to section 3-4 when relay HR is picked up, and when that relay is released alternating current coded at the 75 rate is supplied to the section.

Thecoded current supplied to the exit endgof section 34 is transmitted through the track rails tolocation 3a when subsection 3a-4 is vacant. At location 311 a track relayATR is connected to the track rails. of subsection 3a4 through a receiving transformer RT and a full .wave rectifier I3 so thateach code pulse of alter hating current received by transformer RT; is rectified into and supplied into relay A'IRas a pulse of direct current. As long as subsection 3a& is vacant relay ATR is therefore energized and deenergized in stepwith the on and off intervals of the coded current supplied to the exit end of the section. Relay ATR has associated therewith adecodingtransformer ADT,'a code detecting relay ACDR,,a code generator 15CT and a code repeating relay CTM. Relay ACDR is controlled by relay ATR through the medium of decoding transformer ADT so as to b energized when and only when relayATR follows coded energy, as explained in Letters Patent of the United States No. 2,237,788, granted to Frank H. Nicholson et al. on April 8,1941. The code repeating re lay CTM is provided with an energizing circuit I8 and a track transformer i9 comprising a secondary winding 20 and a primary winding 2I. Each time relay CTM is energized its front contact II closes to connect battery I8 through a lim-= iting resistor IBa across the track rails of subsection 3-3a at its exit end, and each time relay CTM is deenergized its back contact I'I closes to connect secondary windingZIl of transformenlll to the track rails.. The primary winding 2| of transformer I9 is normally deenergized but at timesis supplied with alternating current over a circuit extending from terminal BX through front contact 22 of relayACDR, back contact 23 of a relay CLR, and the primary winding 2 I to terminalCX. The relay CLR is controlled by a line circuit in a manner that will be explained hereinafter, but at this time it should be noted that relay CLR also controlscrossing signal XS over an obvious energizing circuit including back contact 24 of relay CLR. j v r V Acode pulse of direct currentis supplied to the rails of subsection 3 3d each time contact I! of relay CTM closes in its front position to connect battery IBacross the track rails, and'when sub.- section 3-311 is vacant these pulses of coded direct current are transmitted throughthetrack rails to the entrance end 3 where'a direct current track relay is connected across the rails. Under these conditions, relayenergized and deenergized instep with the supply and interruption of current from battery I8 at the opposite end of the subsection. ,Relay'IfR has associated therewith a decoding transformer. DT, a code detecting relay CDR, and a code rate responsive re: lay DR. The code detecting relay CDR is controlled by relay IR through themedium of decoding transformer DT ina nanner corresponding to the control of relay ACDR by relayATR, so that relay CDR is energized whenever relay TR follows coded current and is deenergized Whenever relay TR ceases to follow coded current.

The code rate responsive relay DR is connected to decoding transformer DT in the usual manner through a decoding I8IJDU arranged and proportioned so that relay DR is effectively energized and picked up only when relay TR operates at the I code rate. The energization of relay DR therefore is effective to detect operation of relay TR at the I80 code rate, V

The reference characters 30 and 3|. designate line wires which extend from/the entrance end 3 of the section to the intersection of highway H.with the stretch ottrack. A rline battery 32, a line relay ELR, a decoding transformer EDT and a line controlled relay are located atone end of the -line wires,.w hile a line battery 33, line relay ALR, decoding transformer LDT and the previously mentioned line ccntrolled relay CLR are located at the opposite end of the line wires. The line wires3l1 and-3| are utilized to control the line controlled'relays HLR and CLR,

1 sp n V to. be e p ai ed in. deta he ein: 7

after. Relay Hut cooperates with relay D3 to control wayside signal 38 in a manner such that when relay DR is picked up, lamp G of that signal is energized over an obvious circuit including front contact 35 of relay DR: when relay DR is released and relay HLR is picked up; lamp Y of signal 33 is energized over back contact 35 of relay DR and front contact 36 of relay I-ILR; and when relays DR and l-ILR are released lamp R is energized over a circuitincluding back contacts 35 and 36 of relays DR and I-ILR, respec tively. Code generators 159T and |80CT are provided at entrance end 3, and relay HLR cooperates with these generators and with relays DR and CDR in the control of the coded'energy supplied through a track transformer 3'IT to the rails of the stretch in the rear of section 3 4. When relay DR is picked up, secondary winding H of transformer 3'I'I is supplied with 180 code current over a circuit extending from terminal BX through contact I80 of code generating device EMCT, front contact-"31 of relay CDR, front contact 38 of relay DR and Winding H of transformer 3TT to terminal CX. When relay DR is released and relay HLR is picked up, 180 code current is supplied tothe transformer over a circuit extending from terminal BX through contact I83 of coder IBUCT, front contact 3''! of relay CDR, front contact 39 of relay HLR, back con-' tact 38 of relay DR and winding ll of transformer 3TT to terminal When both relays DR and 'I-ILR are released, "75' code current is supplied to the transformerfrom terminal BX over contact T5 of coder TSCT, back contact 39 of relay HLR, back con-tact 38 of relay DR and Winding I of terminal CX.

The apparatus embodying my invention is in its normal condition when section 3-4 is vacant and relay HR controlled by trafiic in the stretch in advance of section 3 4, is picked up. Under these conditions 180 code current is supplied to the track rails at the "exiten'd of section 3 4 and causes operation of relay ATR at 9; corresponding rate to pick up relay ACDR and operate code repeating relay CTM at a rate corresponding to the rate of operation of relay ATR. Operation of relay CTM by relay A-TR results in the application of 180' code direct current to the rails at the exit end of subsection 3*3a to operate relay TR at a corresponding rate and cause relays CDR and DR at the entrance end of the section to be picked upsothatlamp G01 signal 3S is lighted, and I 80 codecu'rrent is supplied to the section in the rear of section 3'-'4. Each time that relay CTM is picked up to-apply an impulse of direct current-to the track rails and in turn energize relay'TR, aline circuit involving the line wires 39 and 3| is established for relay ALR and may be traced from one terminal of line battery 32 at the entrance end of the section through front contact 40 of relay TR, front contact 4| of relay CDR, line Wire 30, front contact 42 of relay CTM-,- the Winding-of relay ALR, front contact 43 of relay CTM,-line wire 3l, front contact 44 of relay CDR, and front contact 45 of relay TR to the other terminal of battery 32. When relay CTM is deenergi'zed and opens its front contact l! to disconnect battery [8 from subsection 3-3'a, relay TR becomes deenergized and line relay ELR at the entrance end of the section is energized over a line circuit extending from one terminal of battery 33' located'at the intersection, through front contact 415 'of relay ACDR, back contact 42or-re1aycm, line wife 33, front contact 41 of 'relayCDRyb'ack contact 40 of relay TR, the winding of relay ELR, back contact 45 of relay TR, front contact 44 of relay CDR, line wire 3|, back contact 43 of relay CTM, and front contact 4! of relay ACDR to the other terminal of line battery 33. It follows that with subsection 3-3a Vacant, line relay ALR at the intersection is supplied with a pulse of current from battery 32 over the line Wires 30 and 3| each time that relays CTM and TR close their front contacts in synchronism, and that relay ELR at the entrance end is energized with a pulse of current supplied from battery 33 over line Wires 3t and 3| each time that relays CTM and TR close their back contacts in synchronism. The synchronous operation of the contacts of relays CTM and TR therefore enables the line wires 36 and 3| to provide two separate control channels for controlling line relays ALR and ELR located respectively at the opposite ends of subsection 33a. The intermittent ener'giza tion of relay ALR over the line circuit just described is detected by line controlled relay CLR.

through the medium of decoding transformer LDT in the manner previously discussed, and relay CLR therefore is energized and picked up Whenever relay ALR is recurrently energized over the line circuit. The recurrent energization of relay ELR at the entrance end of the section is similarly detected by relay HLR through the me-' dium of decoding transformer EDT. Under the conditions assumed, that is, with relay CLR energized because of the intermittent energization of line relay ALR, crossing signal XS is de'energized.

When a train operating in the normal direction of 'traific in the stretch enters section 34, the pulses of energy supplied from battery l8 through contact I? of relay CTM to the rails of subsection 3-3a are shunted away from relay TR and as a result relays CDR and DR; release. The release of relay CDR results in the opening of the line circuits previously traced for relays ELR and ALR, and those relays are steadily deenergized. The cessation of code operation of relay ELR is detected by relay I-ILR, which releases and as a result lamp G becomes dark while lamp R becomes energized over its previously traced circuit to cause signal 33 to display its stop aspect. The track circuit current supplied to the rails of the stretch in the rear of section 3-4 is shifted to the 75 code rate by the release of relay HLR which completes the circuit for transformer 3TT previously mentioned including contact 15 of coder TECT and back contacts 39 and'38 of relaysl-ILR and DR, respectively. Line controlled relay CLR at the exit end of subsection 33a also releases due to the cessation of code operation of relay ALR and as a result back contact 24 of relay CLR closes to complete the obvious energizing circuit for crossing signals XS, thereby initiating operation of that signal to provide a warning to highway users of the approach of a train to the crossing. The release of relay CLR also results in the supply of alternating current to primary winding 2! of transformer I9 over the previously traced circuit including back contact '23 of relay 'CLR and front contact 22 of relay ACDR, and as a result each time that back contact ll of relay CTM is closed a pulse of alternating current is applied to the track rails. These pulses of coded alternating current in the rails of the subsection may be'utilized in the customary manner to control train carried apparatus on" the train occupying subsection 33a.

When the train enters advance subsection {ta-'4 the coded alternating current supplied to exit end 4 of the section is shunted away from relay ATR'so that relay ACDR releases to open its front contact 22' and deenergize primary winding 2| of transformer 19, thereby terminating the ap plication of coded alternating current to the rails of subsection 3-3a. Contact N5 of relay ACDR. also operates from its front to its back position to shiftthe energization of relay CTM from contact-l5 of relay ATR to contact of code generating device I5CT, and as a result relay CTM operates at the 15 code rate to apply direct current pulses from battery l8 to the track rails at the corresponding rate. When the train vacates subsection 33a, the pulses of current coded at the '75 rate applied at exit end 3a operate track relay TR, and relay CDR is thereupon picked up to close its contacts 4! and M in the circuit of relay ALB. Ihe contacts of relays TR and CTM operate in synchronism to alternately complete and interrupt the circuit of relay ALR at the rate of '75 times perininute, and this operation is detected by relay CLR which picks up to open its back contact 24 and thereby deenergize crossing signals XS,- and to open its back contact 23 in the energizing circuit of primary winding 2| of transformer l9. At this time contacts 46 and 41' of relay ACDR are held open so that the synchronous operation of relays TR and CTM does not result in energization of line relay ELR at the entrance end of the section and no change is effected at this time in the condition of line controlled relay I-ILR. 'The train in vacating subsection: 3-'-3a therefore causes the apparatus embodying my inventionto supply the track rails with coded direct current which is utilized to detect the vacant condition of the section and which causes termination of the operation of the crossing signal but does not alter the control of wayside signal 3S at the entrance end of the section.

When the train'vacates section 3--4 and occupies the stretch in advance of that section, relay HR will be released as is customary in railway signaling practice so that its back contact l2 completes the circuit over which '75 code current is selected for application to the rails of section 3- -4. Relay ATR responds to this '75 code current and picks up code detecting relay ACDR which operates its contact I6 from its back position to its front position to shift the energization transformer HT, and asja result the coded current supplied to exit' end 4 of section 34 is shifted to the -180 code rate and causes relays ATR, CTM and TR to operate at corresponding rates. Relay DR associated with relay TR. thereupon becomes energizedand picks up to close its front contact 35150 complete the-obvious energizing circuit for lamp G of signal and its front contact 38 'to complete the circuit over which 180 code normally is supplied to track transformer 3TT. ;The apparatus is therefore restored to its normal condition as represented in the drawing. 7 a

It is to be noted that in .thisnormal condition of the apparatus, subsection 33a which constitutes a control section for signal XS is supplied with code pulses of 'direct'current. When the control'section is occupied by a ltrain the supply of code pulses ordirect current is maintained 7 while at the same time-a code pulse of alternating current is supplied to the track rails during each ofi period of .the direct current code. These pulses of alternating current are of the type which may be utilized in the customary manner to control apparatus carried on a train occupying the control section. The other section 3a4 is normally supplied with coded alternating current which, .of course; is effective to control'train carried apparatus and the'system organization is thus such that the/complete section 3-4 is supplied with pulses of alternating current whenever such supply is necessary for the control of train carried, apparatus on atrain occupying'the section. Afteratrain vacates the control section the pulses vof alternating current are removed from the track rails and the vacant condition of the control section is detected by coded pulses of direct current which operate wayside apparatus and are detected'by a code detecting relay utilized toestablish control of the highway crossing signal, but no control is effected by this apparatus over the wayside signals governing traffic in the section, Also, should a second train follow the first into section 3-4, thecoded track circuit current applied to the control section while the first train occupies the remaining part of section of relay CTM back to control by contact 15 of rei lay ATR. Relay CTM accordingly continues to operate at the '75 code rate in step with the energization of relay ATR and no change is effected in the operation of the decoding apparatus associated with relay TR. at the entrance end of the section. However, contacts 46 and 41 of relay ACDR close so that line relay ELR at the entrance end of the section is energized each time that relays TR and CTM close their back contacts in synchronism. The coded operation of relay ELR is detected by relay HLR which picks up'to deenergize lamp R and energize lamp Y of signal 33 over its circuit including back contact 35 of relay DR. and front contact 36 of relay I-ILR. Also, the previously traced circuit including back contact 38 of relay DR andfront contact 39 of relay HLR .traflic conditions in the stretch in advance of section 3-4, front cont-act l2 zof that relay closes to complete the circuit over which code current is supplied to secondary winding I I of track 3-4 is not of the type effective to operate train carried apparatus so that the train. lcarried apparatus on the-second train will be conditioned to indicate theoccupi-ed condition of the entire section 7 V a V lt f-o-llows that apparatus embodying my invention is arranged and organized in such-a manner as .to make-use of codeddirect current track circuit energy for detecting the clearing of an approach section for acrossing signal in a stretch of track equipped with a railway signaling system which provides for the control of either or both wayside signals and train carried cab si nals, and'the arrangement is such as not to interby means which provide for the proper control of highway crossing signals and train carried cab signals'in coded track circuit systems of railway signaling. 1 r

Although I -have herein shown and described only one form of railway signaling apparatus embodying my invention, it is to be understood that various changes and modifications may be has th re wrm i he c p pi the ra claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a coded track circuit system of railway signaling for a stretch of railway track in which trafiic normally operates in a given direction, in combination, a section of railway track in said stretch, a track relay at the entering end and a track battery at the exit end :of said section, a contact operable between a first and second position, means'for operating said contact alternately between said positions, a circuit completed in the first position of said contact for connecting said track battery to the rails at said exit end of said section for operating said track relay alternately between a first and a second position in synchronism with the operation of said contact when said section is vacant, two line wire-s extending between the ends of said section, a first battery and a first relay at said entering end of said section and a second battery and a second relay at said eXit end of said section, means governed by trafiic in said section for connecting said first battery in circuit with said second relay over said two line wires when said track relay and said contact are in corresponding first positions, means governed by traffic in said stretch in advance of said section for connecting said second battery in circuit with said first relay over said two line wires when said track relay and said contact are in corresponding second positions, and traflic governing means controlled by said first and second relays.

2. In a coded track circuit system of railway signaling for a stretch of railway track in which trafiic normally operates in a given direction, in combination, a section of railway track in said stretch, a track relay at the entering end and a code transmitting relay at the opposite end of said section, means for operating said code transmitting relay alternately between a first and second position at a rate dependent upon traffic con ditions in the stretch in advance of said section, means controlled by said code transmitting relay for alternately energizing and deenergizing the track rails of said section in step with the operation of said code transmitting relay for operating said track relay alternately between a first and second position in synchronism with said code transmitting relay when said section is vacant, two line wires extending between the ends of said section, a first battery and a first relay at the entering end of said section and a second battery and a second relay at the opposite end of said section, means governed by traffic in said section for connecting said first battery in circuit with said second relay over said two line wires when said track relay and said code transniitting relay are in corresponding first positions, and means governed by trafiic in said stretch in advance of said section for connecting said second battery in circuit with said first relay over said two line wires when said track relay and said code transmitting relay are in corresponding secnd positions.

3. In a coded track circuit system of railway signaling for a stretch of railway track in which traffic normally operates in a given direction, in combination, a section of railway track in said stretch, a tracl; relay at the entering end and a track battery at the exit end of said section, a contact operable between a first and a second position, means for applying coded energy to the rails of said stretch at a point in advance of said section, means controlled by said coded energy when said stretch between said section and said point is vacant for operating said contact alternately between said positions in step with said coded energy, meansv at said exit section end for operating saidcontact alternately between said positions at a given rate when traflic occupies said stretch between said section and said advance point, a circuit completed by said contact in its said first position forconnecting said track battery to the rails at said exit end of said section effective when said section is Vacant for operating said track relay in synchronism with the operation of said contact, two line wires extending between the ends of said section, means controlled in synchronism by said contact and by said track relay for providing two separate control channels: over said two line wires, means governed by trafiic in said stretch in advance of said section for controlling one of said two control channels, and means at the entering end of said section controlled by said one control channel and means at the exit end of said section controlled by the other of said control channels.

4. In combination with a stretch of railway track in which traffic equipped with train carried signaling facilities normally operates in a given direction andincluding a track section, a track relay at the entering end and a track battery and a track transformer at the opposite end of said section, a contact operable between a first and a second position, means for applying coded energy to the rails of said stretch at a point in advance of said section, means controlled by said coded energy when said stretch between said sec tion and said advance point is vacant for operating saidcontact alternately between said positions in step with-said coded energy, means at said opposite section end for operating said contact alternately between saidpositions at a given rate when trafl'lcoccupies said stretch between said section and said given point, a circuit completed by said contact in its saidifirst position effective when said section is Vacant for connecting said track battery to the rails at said opposite end of said section for operating said track relay in synchronism with the operation of said contact, a circuit completed in said second position of said contact for connecting a secondary winding of said track transformer to the rails at said opposite end of said section, two line wires extending between the ends of said section, a first battery and a first relay at said entering end of said section and a second battery and a second relay'at said opposite end of said section, means governed by trafiic in said section for connecting said first battery in circuit with said second relay over said two line wires when said track relay and said contact are in corresponding first positions, means governed by trafiic in said stretch in advance of said section for connecting said second battery in circuit with said first relay over said two line wires when said track relay and, said contact are in corresponding second positions, means at the entering end of said section controlled by said first relay for governing trafiicin said section, and means at said opposite end of said section controlled by said second relay for energizing the primary winding of said track transformer.

5. In combination with a stretch of railway track in which traflic normally operates in a given direction and including a section of railwaytrack intersected by a highway at its exit end, a highway crossing signal at said intersectrack battery at the opposite end of said section, a contact operable between a first and a second position, means for continuously operatingsa-id contact alternately between said positions, a circuit completed in the first position 'of said contact for connecting said track battery to the rails of said section for operating said track relay alternately between a first and a second position in synchronism with theoperation of said contact when said section is vacant,tw'o line wires ex tending between the ends of said section, a first battery and a first relay at said entering end of said section and a second battery and a second relay at said opposite end of said section,

'means governed by traflic in said section for connecting said first battery in circuit with said second relay over said two line wires when said a track relay and said contact are in corresponding first positions, means governed by traflic' in said stretch in advance of said section for connecting saidsecond battery in circuit with said first relay over said two line wires when said track relay and said contact are in corresponding second positions, railway traffic governing means at the entering end of said-section controlled by said first relay, and means at said opposite end of said section controlled by said second relay for operating said highway crossing signal.

6. In a coded track circuit system of railway signaling for a stretch of railway track in which ,traffic equipped with train carried cab signaling facilities normally operates in a given direction, in combination, a section of railway track in said stretch intersected byga highway at its exit end, a highway crossing signal at said intersectiom; a track relay at the entering end and a track battery and a'track'transformer at'said exit end of said section; a contact operable between a first and a second position, means for continuously operatin saidcontact alternately between said positions at a rate dependent upon traflic conditions in said stretch in advance of said section, a circuit completed in the first position of said contact for connecting said track-battery to the rails at said exit end of said section for operating said track relay alternately between a'first and a second position in synchronism with the operation of said contact when said section is vacant a circuit completed in said second position of said contact for connecting a secondary winding of said track transformer to the rails at said'exit end of said section, two line wires extending between the ends of said section, a first battery and a first relay at said entering end of said section and a second battery and a second relay'at said exit end of said section, means governed by traflic in said section for connecting said first,

battery in circuit with said second'relay over said' twoline wires when said track relay and said code transmitting relay are in corresponding first positions, means governed by traffic in said stretch in advance of said section for connecting,

said second battery in circuit with said first relay over said two line wires when said track relay and said code transmitting'relay are in corresponding second positions, means at the entering end of said section controlled by said first relay for governing traffic in said stretch in the rear of said section, and means at said exit end of said section controlled by said second relay for controlling said highway crossing signal and for energizingtheprimary winding of said track transformer.

transmitting device for operating contacts be- 1. tin combination was a stranijtrrn1wav track in which trafiic equipped with train carried cab-signal facilities normally operates in a given direction and including a track section intersected bya highwayat'its exit end, a' highway crossing signal at said intersection, -a track relay at the "entering end anda'track battery and a track'tr'an'sformer at said exitend of said section, a contact operable between a first and a second position, means for applying coded energy to the rails of said stretch ata point in advance of said section, means controlled by said coded energy when saidstr'etcli between said section and saidQpoint is vacant for operating said contact alternately between said positions in step with said coded energy, means at said exit section end for operatingsaid contact alternately between said positions at a given rate when traffic 00- cupies said stretch between said section and said advance point, a circuit completed by said contact in its said first'position for connecting said track battery to the rails at the exit end of said section effective wh'eri'satidsctionis vacant for operating 'said track' relay in synchronism with the operation of said contact, a circuit completed in said second position of said contact for connecting a secondary winding of said track transformer to the rails at said exit end of said sec- 'tion, t'wo line wires extending between the ends 'two line wires when said trackrelay and said contact are in'corresponding secondpositions, means for governing trafiic in said stretch inthe rear of said section controlled'by said first relay, and means controlled by said second relay 'for controlling the operation of said highway crossing signal andfor energizing the primary winding of said track transformer byalternating current;

33. In combination with a stretch of railway track in which trafiic equipped with train carried facilities responsive to coded pulses of alternating current in the track rails normally operates in a given direction, said stretch including an insulated track section provided at its entering end with a wayside railway trafiic controlling signal and divided by insulating joints into adjoining rear and advance subsections, said rear subsection intersected by a highway at its exit end and provided with a'highway crossing signal at such intersection, means for applying to the track rails at the exit end, of said advance subsection alternating current coded at one or another of a plurality of rates dependent upon trafiic conditions in said stretch in advance of said section, a code tween a first and a second position, means controlled by trafiic in said advance subsection for causing said code transmitting device to operate its contacts alternately between said first and second positions at a rate corresponding to the code rate of energy in the rails of said advance subsection, means operative when said advance subsection is occupied for causing said code transmitting device to operate its contacts at a given code rate, a track battery and a track transformer, means controlled by said code transmitting device according as said contacts are in said first or said second position for respectively connecting said battery or the secondary winding of said track transformer to the rails at the exit end of said rear subsection, a direct current code responsive relay connected to the rails at the entering end of said rear subsection and having contacts operable between a first and second position according as said track relay is energized or deenergized respectively, tWo line Wires extending between the ends of said rear subsection, a first line battery and first line relay at the entering end and a second line battery and second line relay at the exit end of said rear subsection, a circuit including first position contacts of said track relay and said code transmitting device for synchronously connecting said first line battery and said second line relay to said line wires, a circuit controlled by traific conditions in the entire track section and including second position contacts of said track relay and said code transmitting device for synchronously connecting said second line battery and said first line relay to said line wires, means controlled by said first line relay for governing said wayside signal, and means controlled by said second line relay for controlling the operation of said highway crossing signal and the supply of alternating current to the primary winding of said track transformer.

9. In combination with a stretch of railway track in which traific equipped with train carried facilities responsive to coded pulses of alternating current in the track rail normally operates in a given direction, said stretch including an insulated track section divided by insulating joints into adjoining rear and advance subsections and provided at its entering end with code transmitting means for supplying the rails of the stretch in the rear of said section with energy coded at one or another of a plurality of code rates depending on trafiic conditions in said section, said rear subsection intersected by a highway at its exit end and provided with a highway crossing signal at such intersection, means for applying to the track rails at the exit end of said advance subsection alternating current coded at one or another of a plurality of rates dependent upon traflic conditions in said stretch in advance of said section, a code transmitting device for opcrating contacts between a first and a second position, means controlled by trafilc in said advance subsection for causing said code transmitting device to operate its contacts alternately between said first and second positions at a rate correspondin to the code rate of energy in the rails of said advance subsection, means operative when said advance subsection is occupied for causing said code transmitting device to operate its contacts at a given code rate, a track battery and a track transformer, means controlled by said code transmitting device according as said contacts are in said first or said second position for respectively connecting said battery or the secondary winding of said track transformer to the rails at the exit end of said rear subsection, a direct current code responsive relay connected to the rails at the entering end of said rear subsection and having contacts operable between a first and second position according as said track relay is energized or deenergized respectively, two line wires extending between the ends of said rear subsection, a first line battery and first line relay at the entering end and a second line battery and second line relay at the exit end of said rear subsection, a circuit including first position contacts of said track relay and said code transmitting device for synchronously connecting said first line battery and said second line relay to said line wires, a circuit controlled by trafiic conditions in the entire track section and including second position contacts of said track relay and said code transmitting device for synchronously connecting said second line battery and said first line relay to said line wires, means controlled by said first line relay for governing said code transmitting means for the rails in the rear of said section, and means controlled by said second line relay for controlling the operation of said highway crossing signal and the supply of alternating current to the primary winding of said track transformer.

CHARLES B. SHIELDS.

REFERENCES CITED UNITED STATES PATENTS Name Date Baughman May 27, 1941 Number

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