Патент USA US2128211код для вставки
Aug.23,1938. TNLJUDGE 2,128,211 RAILWAY SIGNALING SYSTEM Filed Sept. 25, 1956 2 SheetsfSheet 1 93 SN» INVENTOR £7 ATTORNEY Aug. 23, 1938. T. J. JUD'GE 2,128,211‘ RAILWAY S IGNALING SYSTEM Filed Sept. 25, 1956 2 Sheets-Sheet 2 3E] m. “a. “1'05’ TV m .____.____.____________.__ (\l q Q N I Mai d; INVENTOR ma. nu Y - W ATTORINEY ’ ' Patented Aug. 23, 1938 . 2,128,211 UNETED STATES gPATEN'i' OFHQE 2,128,211 RAILWAY SIGNALING SYSTEM Thomas J. Judge, Rio de Janeiro, Brazil, assignor to General Railway Signal Company, Roches ter, N. Y. Application September 25, 1936, Serial No. 102,557 12 Claims. (01. -246—33) This invention relates in general to railway sig naling systems, and more particularly to an abso lute permissive block signaling system employing coded track circuits for controlling wayside and/ or 5 cab signals. In general, it is proposed in accordance with the present invention to provide an absolute permis sive block signaling system employing coded track circuits arranged to effect the control of train 10 movements in both directions through a portion of single track in the usual manner, but without the use of control line circuits. More speci?cally, it is proposed to provide in each block a track cir cuit associated with each direction of movement 15 so arranged that the two track circuits are inde pendent of each other due to the distinctive char acter of their energization. It is then proposed to independently code or modulate the distinctive energization of each of these track circuits in a 2 0 manner to condition wayside and/or cab signals for each direction of train movement in accord ance with forward tra?ic conditions. Other objects, purposes and characteristic fea tures of the present invention will be obvious as 25 the description thereof progresses, during which references will be made to the accompanying drawings, in which Fig. 1 and Fig. 2 show in a diagrammatic and 3 conventional manner the apparatus and circuits of a portion of an absolute permissive block sig naling system arranged in accordance with the present invention. These two ?gures show adja cent portions of the railway track and are intend ed to be placed end to end with Fig. 2 at the right. In the accompanying drawings, a single track portion of a railway has been shown as divided by insulating joints J into track sections or blocks l, 2 and 3, ‘and it is to be understood that this is a portion of single track wherein trains normally 40 move in either direction and passing sidings or portions of double track will be provided at spaced intervals which have not been shown. The present system employs the usual absolute permissive block feature wherein two or more 45 trains are permitted to follow each other through the portions of single track between these passing sidings, but a train is prevented from entering any such single track portion which is occupied by a train moving in the opposite direction. It is be lieved that a description of the portion of the present signaling system associated with the typi cal intermediate portion of single track compris ing blocks I, 2 and 3 will be su?‘lcient for an under standing of the present invention, and inasmuch as the apparatus associated with each of these blocks is identical, the same reference characters have been assigned to the like pieces of apparatus with an exponent corresponding to the particular block with which it is associated. It may be brie?y stated that in the present 5 system each block is provided with two superim posed alternating current track circuits, these two circuits being energized with distinctively differ ent frequencies and reversely arranged with re spect to the ends of the track rails to which the 0 energy is applied, the track rails of course form ing common electrical conductors for both cir cuits. More speci?cally, alternating current en ergy of one frequency is connected to one end of the rails of each block and alternating current 15 energy of a distinctively different frequency is connected to the other end of these same track rails of each block, or as shown on the drawings, the left hand end of the rails of each block is connected through a transformer LTR to a power 20 line LP energized by an alternating current gen erator LG, while the right hand end of these rails of each block is connected through similar trans formers RTR to another power line RP energized by an alternating current generator RG which supplies a different frequency of alternating cur rent than generator LT. It is to be understood however that in the event it is not desirable to ex tend the power line wires LP and RP along the 5 trackway, the two distinctive frequencies of alter- 30 nating current can be generated locally at each block from a battery or the like such as by vibrat ing reed contacts operating at distinctively differ ent frequencies and arranged to interrupt the energization of the primary of transformers LTR 3'5 and RTR respectively, all in accordance with well recognized principles. The particular frequency applied to each end of each block is conducted through the track rails in series to operate a track relay at the other end, ‘10 which track relay is rendered nonresponsive to the different frequency applied at the same end. More speci?cally, the energy applied to the left hand end of each section through transformers LTR is conducted through the rails in series to the primary of a tuning transformer RTA con nected across the right hand end of the rails, the secondary of this transformer RTA being con nected to the primary of a second tuning trans former R'I'B through a tuning condenser RC, 50 whereby the secondary of the transformer RTB is only effectively energized by the alternating current of the frequency supplied by transformer LTR and is not eifectively energized by the alter nating current of the frequency supplied by trans- 55 2 2,128,211 former RTR. Similar transformers LTA and LTB and condenser LC are employed at the left hand end of each section, but the condenser LC as indicated is of a capacity different from condenser RC so that the secondary of transformer LTB is only effectively energized by the alternating cur rent of the frequency supplied by transformer RTR. The secondary of transformer RTB energizes a 10 direct current track relay RT through a full-wave recti?er RR and in a similar manner the second ary of transformer LTB energizes a second direct current track relay LT through a full-wave rec ti?er LR. In this manner, the track relay RT is 15 controlled only by the current from the trans former LTR and track relay LT and is con trolled only by the current from the transformer RTR, and inasmuch as the current from both transformers LTR and RTR flows through the track rails in series, both of these track relays LT and RT will be dropped by a train shunting the associated track section. In order to communicate the traf?c conditions from block to block without the use of control 25 line circuits, the alternating current energization of each of the two track circuits for each of the blocks is individually modulated or coded in ac cordance with traffic conditions in a direction individually associated with each of these- two 30 circuits. In other words, the secondary of trans former LTR is connected to the track rails through a back contact of a code repeater relay LCP which is operated in synchronism with either contact C75 or CWO of a modulator or coder C, 35 and. in a similar manner, the secondary of trans former RTR is connected to the track rails through a back contact of a code repeater relay RCP likewise operated in synchronism with either of contacts CV5 or C188 of a similar coder C. 40. ' The contacts C75 and CESB may be operated in any suitable manner, but for convenience these contacts have been diagrammatically illustrated as operated'by the usual form of mechanical cod ing means wherein a continuously energized mo tor M mechanically operates contacts C75 at the rate of '7 5 times per minute and also operates con tact C | 86 at the rate of- 180 times per minute. The code repeating relays LCP and RCP are at times continuously deenergized, and at other times op 50 erated by either contact C15 or contact CIBI] as selected by traffic conditions as will be later de scribed. the secondary of transformers LTD and RTD respectively through condensers LCE and RCE respectively, which condensers are of a value se lected to resonate or to permit an effective alter hating current voltage in the secondary of trans formers LTE and RTE only when the frequency of alternating current from the secondary of transformers LTD and RTD is provided by the 180 rate of operation of the track relays LT and RT respectively. Similar tuning transformers LT?‘ and RTF are also connected across the sec ondary of transformers LTD and RTD respec tively but through different capacity condensers LCF and RCF whereby an effective alternating current voltage is permitted in the secondary of transformers LTF and RTF only when the fre quency of alternating current from the secondary of transformers LTD and RTD is produced by either the 180 code rate or the 75 code rate of operation of the respective track relays LT and RT. The alternating current produced in the secondary of transformers LTE and RTE energize respective direct current relays LE8!) and RES!) through respective full-wave recti?ers LRE and RRE, and likewise the alternating current pro duced in the secondaries of transformers LTF and RTE‘1 energize respective direct current relays Ll?» and Rl'5 through respective full-wave recti ?ers LRF and RRF. .The track relays LT and RT also control the energization of respective slow releasing track repeating relays LT? and RT? whereby these repeating relays remain picked up either when» the associated track relay is continuously ener gized or is operating at the 75 or 180 code rate, but drop when the associated track relay is con tinuously deenergized. It will now be clear that when the track relays are continuously energized, the associated repeating relays will be picked up but both the associated 180 and 75 decoding relays 40 will be dropped; and when the track relays are operated at the 180 code rate, the respective re peating relays and both the respective 180 and 75 decoding relays will be picked up; but when op erating at the '75 code rate, the respective '75 decoding relays and the respective repeating re lays only will pick up; and obviously when the track relays are continuously deenergized due to a train shunt for example, all of these'relays will be dropped. A direction stick relay LS and RS is also asso ciated with each block, which stick relays are It will now be clear that when the code re- > made slow releasing for a purpose later described. peating relays LCP and RCP are operating to These directional stick relays LS and RS are se interrupt their associated track circuits at either lectively energized according to the direction of the '75 or the 180 code rate, the respective track a train movement over the associated portionv of relays LT and RT are operated in synchronism track, or that is, relay LS is picked up by an east therewith, and consequently the rate of operation bound train movement and relay RS is picked up of the armatures of relays LT and RT as affecting by a west bound train movement. The present wayside equipment may be em GE) 60 certain decoding means determined the respective forward tra?ic conditions. The decoding means ployed to control either wayside or cab signals or controlled by both track relays LT and RT is both, and consequently the method of effecting identical and comprises respective transformers the control of both types of signals has been LTD and RTD having a center tapped primary shown in the accompanying drawings, although it is to be understood that train movements are connected to one side of a direct current source of adequately protected by either type and conse energy while the two extreme ends are alternately connected to the other side of this source of quently either wayside on cab signals may be em energy by front and back contacts of the respec ployed alone and the other omitted from the sys tive track relay LT or RT. In this manner, al tem. The wayside signals have been illustrated as the 70 ternating current is- induced in the secondaries of transformers LTD and RTD which is propor three indication multiple unit color light type al tional in frequency to the rate of operation of though other types may be equally well employed, and the change in the controlling circuits neces the respective track relays LT and RT. sary when using these other types will be obvious Decoding transformers LTE' and RTE‘ are pro vided having primary windings connected across to those skilled in the railway signaling art. The 75 2,128,211 wayside signals ES govern tra?ic in east bound direction through their associated block and are jointly controlled by the associated decoding re lays LI8I! and L15, and likewise the wayside sig nals WS govern tra?c in a west bound direction and are jointly controlled by the decoding relays RIBIJ and R15. A west bound train represented by wheels and axle 5 has been shown as occupying section 3 of 10 Fig. 2, and a cab signal system which may be employed in the present system has been shown diagrammatically as carried by such train, but it is to be understood that the particular arrange ment of such car carried equipment is shown 15 merely for an example and that various other well known types of car carried signal controlling sys tems can equally well be employed. In Fig. 2, the car carried equipment is illus-u trated as comprising receiver coils 6 and 1 car 20 ried on the train above the rails and in front of the ?rst pair of wheels and axle whereby current is induced in these receiver coils by the alternat ing current flowing in the track rails from trans former LTR3. A means similar to that employed 25 in the wayside equipment may be used to tune the circuit of the receiver coils to the particular fre quency of alternating current received from the rails, or that is, the receiver coils 6 and 1 are con nected in series to the primary of a tuning trans former 8, the secondary of transformer 8 being connected to the primary of a second transformer 9 through a condenser I0 whereby the secondary of transformer 9 is only effectively energized by the alternating current of the frequency provided 35 by transformers LTR when the train is traveling in a west bound direction. However, when the same train is traveling in an east bound direction, the alternating current af fecting the receiver coils will be of a different fre 40 quency supplied by transformers RTR, and con sequently it is contemplated that a manually op erable switch II may be provided which in this case of an east bound direction of movement will be moved from its west bound position W to its 45 east bound position E to connect a condenser I2 in multiple with condenser I I], and thus tune this circuit to the frequency of transformer RTR. However, it may be considered sufficient in some applications to arrange the tuning of the car car 50 ried receiver circuit su?iciently broad so that the secondary of transformer 9 will be effectively en ergized by the frequency of current received from either transformers LTR or RTR, and in such case the switch I I and condenser I2 may be omit 55 ted. The remaining portion of the car carried equip ment may be constructed in accordance with the usual practice and has been illustrated diagram matically as an amplifying means A amplifying 60 the current from the secondary of transformer 9 to a value which can operate a master relay MR. The master relay MR, then operates in synchro nism with the operation of the particular code re peating relays LCP or RCR the same as the track 65 relays LT and RT, and consequently a decoding means similar to that employed in the wayside arrangement may be employed. ' This car carried decoding means comprises a transformer I4 operating the same as transformer 70 RTE in the wayside equipment but from a con tact of the master relay MR rather than a track relay RT. The output of transformer I 4 then en ergizes a decoding relay D I 80 through recti?er I5, tuning transformer I6 and condenser I6 only when the 180 code rate is received from the rails, 3. and the output of transformer I4 likewise ener gizes a decoding relay D15 through recti?er I9, transformer 20 and condenser 2| when the 75 or the 180 code rate is received, all in a manner which may be understood from the previous de scription of the wayside decoding equipment. Having now pointed out the essential elements of the present system, it is believed that the use fulness and the various interrelated functions of the apparatus and circuits of the present embodi ment will be more readily understood by vfurther description being given from the standpoint of op eration. 10 Operation Considering that the illustrated west bound train represented by wheels and axle'5 is the only train traversing the portion of the railway system under consideration, this train then receives a clear or green cab signal as well as a green way side signal. In other words, sections I and 2 being unoccupied, the code repeating relay LCPZ is con" nected to contacts CI80 of coder C1 through front contact 25 of relay RTP1 and front contact 26 of relay R151, thereby operating contact 21 of relay LCP2 to impulse the energization of section 2 from transformer LTR.2 at the rate of 180 times per minute which picks up the track repeater relay RTPZ at front contact 32 of relay RT2 and the decoding relays R152 and RIBIl2 are also energized by the operation of contact 33 of relay RT2. The green signal lamp G of signal WS2 is then ener—' gized through front contact 28 of relay R152 and front contact 29 of relay RI8U2. In a like man ner the green light G at signal WS1 is energized through front contacts 48 and 49 of relays R151 and RI 351 respectively, and at all west bound sig 15 20, 25,. at; nals as far as the next passing track at the left of the illustrated portion of single track, a green signal will likewise be displayed. The present train while occupying section 3 40. also receives a green cab signal due to the fact ‘ that code repeater relay LCP3 is connected to contact CISQ of coder C2 through front contact Si! of relay RTF2 and front contact ill of relay R152, thereby operating contact 60 to impulse the energization of section 3 from transformer LTR3 at the 180 code rate. The reception of these 180 code impulses by receivers 6 and 'I then operates contact I3 of the master relay ME to effect the energization of relays D15 and DI Bil as previously described, and the green cab signal G is then en ergized through front contacts 34 and 35 of re lays D15 and DISI] respectively. The east bound signal ESZ, however, properly displays a red or danger indication due to the continuous deener gization of track relay LT3 caused by the occu pancy of section 3, thus dropping relay LTP3 at open front contact 38, and dropping relays LI8IJ3 and L153 due to the inaction of contact 31, and the red signal lamp R of signal ES3 is then en ergized through back contact 38 of relay L153. The LTP3 and L153 relays and the east bound stick relay LS3 being deenergized, obviously pre vents energization of the code repeater relay‘ RCP2 thus continuously supplying the right hand end of section 2 with alternating current from transformer RTR2 through back contact 39 whereby track relay LT2 is continuously ener gized to drop the decoding relays LIBil2 and L152 by the inaction of contact bill, and the red lamp R of the east bound signal E62 is then energized through back contact M of relay‘L152'. Likewise the deenergization' of the decoding relay L1552 and the east bound stick relay LS2 prevents the en 69 2,128,211 ergization of the code repeating relay RCP1 thus‘ supplying continuous energy to the right hand end of section i from transformer RTE1 through its back contact ill, and it will be clearthat the . right hand end of each section in advance of the west bound train will be supplied with continuous or uninterrupted alternating current so that a red east bound signal indication will be displayed at each block of the single track to prevent any 10 east bound train from entering the portion of single track during the present west bound train movement. ' Considering now that the present train in Fig.‘ 2 passes the insulating joints J and enters sec 15 ‘tion 2, it will be clear that track relay RT2 will now be continuously deenergized to drop the de coding relays Rl'52 and BMW and energizes the red signal lamp R at signal WS2 through back contact 23 of relay BT52. The car-carried re 20 'iceivers S and 7 however, DOW receive current llTl pulses of the 180 coderate from transformer LTR2 which obviously maintains the green cab signal G energized the same as while occupying block 3. When the present train is passing the insu~v lating joints J separating blocks 2 and 3, it will be clear that the track repeating relays RTP2 and LTP3 will both be deenergized by contacts 32 and 35 respectively, and although these track repeat~ 36"iier relays are necessarily somewhat slow releasing the decoding relays are necessarily still slower to‘ release due to the shunt across their windings provided by the associated full-wave recti?ers. Consequently the track repeater relay RTP2 will iidrop before the decoding relay EH32 drops, and a circuit is then momentarily completed to pick up the west bound stick relay RS2, which circuit may be track from (+), back contact 42 of relay RTPZ, back contact 43 of relay LTP3, front con 40 tact M of relay RS552, through the windings of re lay RS2, to (—). “Then the stick relay RS2 has picked up, it will be clear that relay R152 subse quently drops, and a stick circuit is then com pleted through front contact 45 of relay RS2 and back contact 413 of relay R7752 to hold relay RS2 in 45 its picked up condition, the stick relay RS2 being suf?ciently slow releasing to retain its armature in its attracted position during the momentary interruption of .its energization caused by the movement of contact 44. 50 The entrance of the present train into block it obviously disconnects the code repeating relay LCP3 from the contact ClSii of the coder C2 at front contacts 30 and 3d of relays RTP2 and R752 55 respectively, but when the west bound stick relay Rszgpicks up, the code repeating relay LCP3 is connected to contact C15 of the coder C2 through front contact 66 of the relay RS2. In this man ner the entrance of the present train into section 60 '2 changes the energization of _ section from transformer L'TR,3 from the 180 code rate to the '75 code rate. Now considering that the present train trav erses section 2 and enters section I of Fig. 1, it will be clear that track relay RTI will drop and the decoding relays R351 and R5861 will be de energized due to the inaction of contact iii, thus changing the indication at signal WS1 from a green to a danger or red indication by energizing 70 the red lamp B through back contact 48 of relay R151. Likewise when the present train passes the insulating joints J separating sections l and 2, the dropping of the track repeater relay RJPl be fore the dropping of the decoding relay R151 75 establishes a pick up circuit for the west bound stick relay RS1, which circuit may be traced from (-|-) , back contact 50 of relay RTPl, back contact 5! of relay LTP2, front contact 52 of relay R151 through the windings of relay RS1, to (—). A similar stick circuit is completed upon the subse quent dropping of relay R151 to hold up relay RS1 through its stick contact 53, and the drop ping of relays RTP1 and R151 disconnected the code repeating relay LCP2 from the Cl80 code contact at open front contacts 25 and 26 respec tively, and the picking up of the stick relay RS1‘ connects the LCP2 relay to the contact C15 of the coder C1 through its front contact 55. The coder repeating relay LCP2 now inter rupts the energization of section 2 from trans former LTR.2 at the 75 code rate by its contact 2?, which in an obvious manner picks up relay R752 in Fig. 2 but allows relay RIBEIZ to remain deenergized. A caution signal indication is then displayed at signal WS2 by energizing the yel 20; low signal lamp Y through front contact 28 of relay R7552 and back contact 29 of relay REBUZ. The picking up of the decoding relay R152 ob— viously releases the west bound stick relay RS2» at contact M inasmuch as the repeating relays 25, RTP2 and LTP3 are now both picked up, and the code repeating relay LCP3 is disconnected from coder contact C75 at open front contact 46 of relay RS2 and is again connected to coder con— tact C980 through front contacts 30 and M of o relays RTP2 and R752 respectively. The ener gization of section 3 from transformer LTRF' is now interrupted at the 180 code rate by contact 6!} of relay LCP3, which in an obvious manner provides a clear west bound signal at the en trance to section 3, which signal hasrnot been shown in the accompanying drawings. In this manner, it will be seen that a train traversing a portion of single track picks up the stick relays associated with its particular direc— tion of travel to allow a second train traveling in the same direction to follow at a safe distance in the rear of this first train. However, it may be seen that the stick relays associated with the opposite direction of travel do not pick up, or 45 that is, considering the present west bound train movement, it is evident that the entrance of the present train into section 3 before section 2 causes the relay L753 to be deenergized before the pick up circuit for stick relay LS3 is closed at back 507'. contacts 132 and 1343 of relays RTP2 and LTP3 re spectively. ' > It will of course be clear that the three differ ent cab signal indications are displayed on the train in the same manner as at the wayside sig nals, or that is, a green cab signal G is ener gized as previously described by the reception of the 180 code rate of impulses by the receivers 6 and ‘i, while the reception of the '75 code rate of impulses drops relay Ditii and completes an 60 energizing circuit for the yellow cab signal Y through front contact 34 and back contact 35 of relays D15 and Dita respectively, and the reception of either uninterrupted alternating cur— rent or the reception of no current by the re ceivers B and l obviously deenergizes both re lays D'l5 and D589] to energize the red signal lamp R‘ through'back contacts 34 and 55 of re lays D'l5 and D! 89 respectively. The operation of the apparatus of the present 70 system associated with an east bound train move ment is similar in every respect to the opera tion just described of the apparatus associated with a west bound movement, and consequently it is believed unnecessary to describe such op 5 2,128,211 eration in detail. The stick relays LS are of course picked up by an east bound train move ment to allow east bound trains to follow in the same manner that relays RS were picked up by a west bound movement, and the west bound wayside signals WS then all display a stop in quency to the other end of each section, a track relay at said one end of each section responsive only to the alternating current of the second frequency, a track relay at said other end of each section responsive only to the alternating current dication in a similar manner during ‘such an east of the ?rst frequency, means for distinctively coding the alternating current of the ?rst fre bound movement. Likewise during an east bound movement of the illustrated train, the switch ii is moved to position E as previously described whereby to tune the receiver circuit to the fre quency of alternating current supplied by trans~ former RTR, and otherwise the car carried quency in accordance with traflic conditions in one direction, means for distinctively coding the alternating current of the second frequency in 10 accordance with tra?ic conditions in the other di rection, and decoding means individually con trolled by each track relay and distinctively re equipment functions the same as during a west 15 bound movement. sponsive to the coding of the associated frequency An absolute permissive block signaling system has thus been provided wherein three-indica 2. In a single track railway signaling system, tion wayside and/or cab signals are controlled without the use of control line circuits to per 20 mit following train movements through portions of single track but to prevent a train from enter ing a portion of single track which is occupied by a train moving in the opposite direction. The feature of the present invention permitting such 25 double direction operation without control line , 15 a plurality of insulated track sections, means for applying alternating current of a first frequency to a ?rst end of each section, means for applying alternating current of a second frequency to the 20 second end of each section, a track relay at said ?rst end of each section responsive only to the alternating current of said second frequency, a track relay at said second end of each section responsive only to the alternating current of said 25 circuits in, the arrangement ‘of superimposed al ternating current track circuits. These track circuits, although each having the track rails as ?rst frequency, means for distinctively coding the alternating current of said ?rst frequency in common conductors are in effect two separate tion, means for distinctively coding the alter 30 and distinct circuits‘, each circuit being indi vidually coded and associated with one particu lar direction of travel. These circuits are also reversely arranged with respect to the ends of the track rails to- which energy is applied so 35 that each direction of train movement progresses toward the source of energy in the circuit asso ciated with that direction of movement, thereby permitting cab signal equipment to be properly controlled during each direction of movement and enabling tra?ic conditions at each block to be transmitted to the rear blocks in each di rection by the respective circuit. Another important feature of the present sys tem is the method of effecting a stop indica 45 tion at all signals governing traffic in a direction opposite to- an established train movement. This method consists in supplying uninterrupted al ternating current to the track circuit of each block associated with such opposite direction of 50 traf?c, which uninterrupted alternating current effects a stop indication at all signals controlled thereby. A particular advantage of this feature is that the track circuits are still able to detect between the occupied and the unoccupied condi 55 tion of their associated blocks, and consequently other apparatus such as highway crossing signals may be conditioned directly by the track relays or the track repeater relays of these blocks in the usual manner. 60 of alternating current. The above rather speci?c description of one form of the present invention has been given solely by way of example, and is not intended in accordance with tra?ic conditions in one direc nating current of said second frequency in ac cordance with traf?c conditions in thevother die rection, decoding means individually controlled by each track relay and distinctively responsive to the coding of the associated frequency of alter nating current, and wayside signals controlled by 35 the decoding means. 3. In a railway signaling system, a portion of single track divided into insulated track sections, means for simultaneously applying differently characterized energy to opposite ends of each section, a track relay at each end of each sec tion responsive only to the energy applied to the opposite end, means for individually impulsing the energy applied to each end of each section to form codes according to tra?ic conditions, and decoding means operated by each track relay for distinctively responding to said codes. 4. In a railway signaling system, a portion of single track divided into insulated track sections, means for simultaneously applying differently 50 characterized energy to opposite ends of each sec tion, a track relay at each end of each section re sponsive only to the energy applied to the op posite end, means for impulsing the energy ap plied to one end or to the other end of tion in accordance with the direction ment of a train through the portion track, and signal controlling means at each sec of move 55 of single each sec tion distinctively conditioned by the impulsing of the energy applied to the associated section. 60 5. In a railway signaling system, a portion of single track divided into insulated track sections, any manner whatsoever in a limiting sense. It means for applying interrupted alternating cur is to be understood that various modi?cations, rent of one frequency to the exit end of each 65 adaptations and alterations may be applied to section for each direction of train movement 65 meet the requirements of practice, without in ‘ thereover, means for simultaneously therewith any manner departing from the spirit or scope applying uninterrupted alternating current of a of the invention, except as limited by the ap different frequency to the entrance end of each pended claims. section for each direction of train movement What I claim is: 70 thereover, and signaling means controlled by said 1. In a single track railway signaling system, interrupted alternating current to display a clear a plurality of insulated track sections, means indication and controlled by said uninterrupted for applying alternating current of a ?rst alternating current to display a stop indication. frequency to one end of each section, means for 6. In a railway signaling system, a portion of single track divided into a plurality of track sec 75 75 applying alternating current of a second fre 6 In 2,128,211 tions, means for simultaneously applying alter nating current energy of distinctively different frequencies to opposite ends of each section, means for coding the energy applied at each end of each section in accordance with traffic condi tions in the two sections respectively adjacent thereto, and signal controlling means governed by the coding of the energization of each section. '7. In a railway signaling system, a portion of single track divided into track sections, means 10 for simultaneously applying alternating current energy of different frequencies to opposite ends of each section, means for coding the energy applied to each end of each section in accordance with tra?ic conditions throughout the sections 15 respectively adjacent to each end, wayside signals responsive to the coded energy, continuous in current at the west end of the section, a track relay at the west end of each section responsive only to the frequency of alternating current at the east end of the section, means operable to intermittently connect the east source of alter- , nating current to the east end of each section to form codes distinctive of west bound traffic conditions, means operable to intermittently con nect the west source of alternating current to the west end of each section to form codes dis 10 tinctive of east bound tra?'ic conditions, code responsive means controlled by the track relay at the east end of each section for governing the west bound signals, and code responsive means controlled by the track relay at the west end of .' each section for governing the east bound signals. 10. In combination, a stretch of railway track ductive cab signaling means, and selective means ' divided into track sections, an east source of a1 for rendering the cab signaling means responsive to one frequency or to the other frequency of the alternating current energy applied to the sections in accordance with the direction of travel. 8. In combination, a stretch of railway track divided into sections, a ?rst source of alternating 25 current, a second source of alternating current of a different frequency than the ?rst source, a code following track relay at one end of each section responsive to the ?rst source of alternat ing current only, a code following track relay 30 at the other end of each section responsive to the second source of alternating current only, means for supplying impulses of alternating cur rent to each section from one of said sources of alternating current in accordance with the direction of a train movement through the stretch of track, means for supplying continuous alternating current tov each section from the other source of alternating current, signals at each end of each section governing traf?c in 40 opposite directions, and signal controlling means controlled by each track relay for effecting a most restrictive indication when the associated track relay is energized by continuous alternat ing current and for effecting lesser restrictive , indications when energized by impulses of alter nating current. 9. In combination, a stretch of railway track divided into track sections, each bound and west bound signals at the ends of each section, an east source of alternating current energy of one ' frequency at the east end of each section, a west source of alternating current energy of a dif ferent frequency at the west end of each section, a track relay at the east end of each section ~ I responsive only to the frequency of alternating ternating current energy of one frequency ap plied at the east end of each section and simul 20 taneously a west source of alternating current energy of a different frequency at the west end of each section, means operable to intermittently connect the east source of alternating current to the east end of each section to form codes dis tinctive of east bound traf?c conditions contem poraneously therewith and means operable to intermittently connect the west source of alter nating current to the west end of each section to form codes distinctive of west bound traffic ‘ conditions. 11. In combination, a stretch of railway track divided into track sections, means for applying alternating current of different frequencies to opposite ends of each section, a track relay at ‘ each end of each section responsive only to the alternating current of the frequency applied to the opposite end, means controlled by the track relay at one end of each section for governing tra?ic in one direction, and means controlled by the track relay at the other end of each section for governing traf?c in the other direction. 12. In a railway signaling system, a portion of single track divided into a plurality of track sec tions, means for simultaneously applying alter nating current energy of distinctively different frequencies to opposite ends of each section, means for coding the energy applied at each end of each section in accordance with traflic condié tions in the two sections respectively adjacent ‘ thereto, and cab-carried signal controlling means governed by the coding of the current energiz ing each section. THOMAS J. JUDGE.