US2353421A - Railway traffic controlling apparatus - Google Patents

Description

July 11, 1944. Q E STAPLE'S 2,353,421

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 19, 1941 5 Sheets-Sher, 1

lbszbaund iNVE o i Fly. [0. "(figwib igf ples HIS ATTORNEY July 11, 1944. c. E. STAPLES RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 19, 1941 WSW g- W 1 2 1 ifm m w TQM N m li m. .7 s m 5 F m MB2 w Aw 4%. B J 0 $1 3 0 W 0 July .11, 1944.

C. E. STAPLES RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 19. 1941 INVENTOR UPOwF [75ft] [93 BY I 5 Sheets-Sheet 3 WSHQ H H15 A'i'TORNEY July 11, 1944. CQE STAPLES I I RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 19, 1941 5 Sheets-Sheet 4 M NIHHI I P I HIHWI HM HH IHHHHHH UHHH MHIWHHIQ HHH.HHHH -l l nl nHHHH l lHH PHIHHHH HMHHM IJ Pu I INVENTOR (bawio ESzapZes HIS ATLI'ORNEY July 11, 1944.

c. E. sTAPLEs RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 19. 1941 5 Sheets-Sheet 5 INVNTOR (Maia 17. 51

a 95 BY pl [[15 ATTORNEY Patented July l1, 1944 UNITED STATES PATENT op -1 RAILWAY maififi zoivraongu Crawford E. Staples, Pittsburgh, Pa., assignor m- The Union Switch & Signal Company, Swiss-' vale, Pa., a corporation of Pennsylvania I Application September 19, 1941, Serial No. 411,481

23 Claims.

My invention relates to railway traffic controlling apparatus and is directed more particularly to apparatus for controlling tramc on a single track, two direction stretch of railroad from a central control oflice over a coded line circuitwhich may be the usual C. T. C. line; My invention dispenses with allof the usual control line wires and permits movement of trains through the stretch without requiring the 'operation of any of the usual tramc levers, it being sufilcient to clear the entering headblock signal for the desired direction by movement'of the associated signal lever in order to set up com- 3 pletely a given trafllc direction. My invention also provides for flexible control of train movement in either direction over the stretch, from either headblock signal location in'the event of failure of the coded line circuit or any of the C. T. C. equipment involved in the trafllc direction control.

One object of my invention is to provide a normally deenergizedsystem of the above, type in [which the control of tramc for a given direction resides predominantly in the apparatus at the entrance end for that direction. Another object of my invention is to detect unoccupancy 'oi the single track stretch by means of an im-' pulse of steady or uncoded energy; apply n a master code thereafter for clearing the entrance signal and for establishing proper signal indications consistent with traflic conditions'in advance. A further object of my invention is to employ a reverse or feed back code which fol lows the train and which deenergizes the track circuits when the train has passed out o! the stretch. A still further-object of my inventionis-to provide a safe,'ilexible, simple and economical system for controlling and expediting -tive in preparation for a cally deenergizing the coding equipment at the exit end when the train leaves the stretch and cascading the deenergizing action to the enter ing end so as to render the track circuits inacsubsequent traflic direction reversal. 1 a

'My invention makes provision for the" headblock signals to remain normally lighted, with the intermediate signals becoming lighted only the need for a traillc' control lever, thus saving trailic movement over a stretch of single track,

two directiohrailrbad. Other objects, advantages and' characteristic features of my invention will appear from thedescription which'follows.

I accomplish the foregoing objects by: aDD1y-.-

ing an impulse of steady energy at the entrance end for the desired traflic direction and cascading the steady energy impulse over the stretch to detect unoccupancy; registering the receipt of the steady'energy impulse at the exit end whereby master code is applied at the exit end;

' cascading the master code over the stretch to the space on the. control machine and simplifying operation.

My invention is an improvement on the apparatus shown in the application for Letters Patent of the United States, Serial No; 403,502 filed by Ralph R. Kemmerer on July 22, i941, now Patent No. 2,316,961, dated April 20, 1943, and

Serial No. 410,504, filed by James J. Vanhorn on September 12, 1941, both for Railway tramc controlling apparatus.

In the accompanying drawings,

applied to a stretch of single track between two passing sidings. Figs. 2a and 2b taken together, with Fig. 2a at the left, are a diagrammatic view showing a modified .formof the apparatus of Fig. ,1, also embodying my invention, and showing advance pick-up stick relays at the intermediate location to provide for following moves, instead of the usual directional stick relays as shown in Fig. 1.

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

' Referring first to Figs. 1a, 1b and 1c, the stretch of track between the sidings SI and S2 isdivided by means of the usual insulated rail joints at 10- bations D, E, F, G, and H into the track circuit entranceend and clearing the headblock signal when this code is received at that end; applying a reverse code in the rear of the train and following the train with this reversecodeas thenated in a similar manner in accordance with train progresses over the stretch; and automatisections l, 2, I, and I. Located at the end of the siding SI is the eastbound headblock signal ESP, and at the end of siding S2 is the corresponding westbound signal WSH, other signals being desigand 10 when placed side by side with 111 at the left are a diagrammatic view showing one 7 vform of apparatus embodying my invention as the trailic direction which they control and their location in thestretch. The various relays are neutral or vertical position to the R position when a right-hand or eastbound move is to be made,

and by moving the westbound signal lever WSLto f the L position when a left-hand or westbound move is to be established.

As shown, all of the coded, track circuits and the intermediate signals are deenergized, only the neutral sWitCh' track circuits I and 4 for the OS sections at the passing sidings, and the headblock signals ESD and WSH (and associated siding signals) being energized. These signals normally occupy the stop position, as shown.

When the operator wishes to permit an'eastbound move through the single track stretch, he will move lever ESL at the oflice from its neutral to its R position and press the usual code starting button (not shown), thereby transmitting a code to the field station apparatus at location E to energize the eastbound trafiic relay ZEHSR at that location. This control code is transmitted over the coded line circuit, which operation energizes ternlinal 85 of the field station unit. It will be understood that the coded line circuit comprises but one pair of line wires connecting the ofilce with each field station, the broken lines which I have shown connecting the office with the various field station terminals suchv as 55, 86, 9|, etc. being merely symbolic of code nals, as required. The numbering of these terminals corresponds with the numbering shown in the United States Patent No. 2,229,249, granted to Lloyd Y. Lewis on January 21, 1941, for

a transmission which puts energy on these te-rmi- Remote control system, and reference may be had to this patent for details of the intervening.

C. T. C. apparatus. This apparatus forms no part of my invention and it will be sufficient for an understanding of my invention to state that operation of the lever at the oflice energizes certain field station terminals whereas energization of certain other field station terminals causes energization of certainapparatus at the oflice as will be described hereinafter.

of contact 26 butduring the release time of this relay, before its front contact 21 opens, relay IECTPR is picked up for a period of time over a circuit which includes the front contacts 28, 21, and 29 of relays 2EHSR, 2EBHSR, and IWTR,

respectively. The pick-up of relay 2ECTPR connects the track battery TB across the track over the front point of its contact 59, thus transmitting an impulse of steady energy eastward over the-single track stretch.

The steady energy impulse is received at the intermediate location F by relay 2WTR which thereupon closes its front contact 3| to energize relay SEC'I'PR and so to cascade the steady energy impulse into section 3. The circuit for relay 3ECTPR includes front contact 3| of relay 2WTR and back contacts 32 and 33 of relays 2WHR j and; 2WD.. At location G, the steady energy picks up relay SWTR'Which, in closing its front contact 34, energizes relay 3WE$A 9V9? an obvious circuit which includes the back contact 35 of relay 3WCDR.

When the impulse of steady energy in track section 3 is terminated (as will occur due to the release of relay ZEBHSR and the deenergization of section 2 with the consequent release of relay SECTPR), relay 3WTR will. release, closing the back point of its contact 34 and establishing a momentary pick-up circuit for relay SWBSR- over back' contacts 35 and 34 of relays EWCDR and BWTR, and front contact 36 of relay SWFSA. The pick-up of relay 3WBSR closes front contact 36 so as to energize terminal 89 of the field station unit and, so to light up the eastbound trafiic light EB on the ofiice panel, thus indicating unoccupancy of the stretch. It will be understood code to be supplied to the track at location G for transmissionover the stretch in the lefthand or westbound direction. Since the headblock signal ESG is at stop, its home relay 4EHR (shown operated by this signal through the broken line connection, for simplicity) will be released so that code will be supplied to sec-'- tion 3 by virtue of the code operation of relay 3WCTPR over a circuit which includes the coding contact 39'of transmitter 150T, back contacts 40 .and 4| of relays 4EHR and 3WCDR, front point of contact 42 of relay 3WBSR, back contacts 43 and 44 of relays 3WHR and SWHSR,

and front contacts 45 and 46 ofrelays 3WBHSR and GETR. Relay 3WCTP R will operate its front contact 41 at the 75'code rate and will accordingly transmit 75 code from battery TB to section 3.

At the intermediate location F, relay 3ETR will have its circuit closed over the back point of contact 48 of relay 3ECTPR and so will follow the 75 code and will energize the decoding transformer 2EDT in the usual and well-known manner over its contact 49, thereby causing relay 3EHR' to become energized. Pick-up of relay 3EHR energizes the eastbound directional stick relay 3ED over a circuit which includes the back contact 50 of the cut-out relay 200R, front point shown and described in my United States Patent No. 2,244,901 granted on June 10, 1941. Relay SED' remains picked up thereafter over a stick circuit which includes front contacts 63 and 64 of relays 3EHR and 3ED. Pick-up of the eastbound directional stick relay SED energizes thecode transmitters 150T and lCT at location F over its front contact 55. A code circuit is now established for operating relay -2WC'I'PR which applies code to section 2, the code being 180 since the forward section 3 is receiving 75 code, The circuit for relay 2WCTPR includes The use of a common decoding relay for either direction of trafiic movement iscontact 56 of code transmitter H901. and front points of contacts '31 and 59 of relays 3EHR and ofwinding The operation 6: relays 2ECTPR zr'and'iE'IR is so arranged that relay ZECTPR 3ED. The 180 code is received by relay IETR at location E over back contact 59 of relay IECTPR, thus energizing the decoding transformer IEDT and causing response not only of the code detecting relay ZECDR which responds to either '75 or 180 code, but also of the 180 code decoding relay 2EDR which responds selectivelyonly to 180-code because of the presence of the resonant decoding unit 'IBODU.

closes the front point of its contact 59 to transmit a feed back impulse', during the "ofP interval in the-'75 master code being received by relay IETR. The manner in which this operation takes place is well known, being described for example in United States Reissue Patent No..

,I'he pick=up of relay 2EDR will cause the eastbound headblock signal ESD to clear by means of signal control circuits which are well known and which therefore have not been shown in order to simplify the disclosure, The clearing of-slgnal ESD results in the red ("stop) 21,783 granted to Herman G. Blosser on April 29, 1941, so that a detailed description of this operation is unnecessary.

As long as 75 master code is being received by relay ZETR, impulses of feed back code are supplied to section 2 and these operate relay IWTR at location F at the 75 code rate. Relay ZWTR. (and the other track relays of my system) is provided with a stick winding which improves opsignal indication lamp 60 on the ofllce panel becoming extinguished and the green (clear) eastbound lamp 6| becoming lighted by virtue of the deenergization of terminal 90 and energization of terminal 94 of the field station unit, which actionresults in the transmission of appropriate codes to the oflice which govern the illumination of these lamps. Since the eastbound headblock signal is clear, the train may proceed over the approach or OS track section I into the single track stretch.

The presence of the train in the "08 section D--'E which includes the track switch -is indiiECTPR will be energized intermittently by the impulse transformer 3EII over the front point of contact 32 of relay 2WHR and, the back point vof contact 33 of relay 2WD. Relay 3ECTPR cated on the oiilce control panel by the lighting of the OS lamp IOSL which results from the energization of terminal 9i of the station unit over the back contact 62- of relay IWTR. 'As' soon as signal ESD changes to stop, a corre-' sponding change will occur in'the indication provided by the lamps 80 and 81 on the oihce panel. As soon as the train accepts signal ESD and lamp lOSL becomes lighted, the operator may; restore lever ESL to its neutral position. The left-hand position of lever ESL would be, used in controlling westbound trafllc beyond signal WSE. The lamp associated with this position of the lever'indicates whether signal WSE is at stop or at proceed.

when the train asses beyond the lemma.

diate location F andvacates section 2, 75 master code is transmitted from this location back to locationiE, and feed back code is transmitted in the direction of train travel, from location E to location F. By master code I mean the ordinary signal control code which is employed in.

coded track circuit signaling;- whereas by,-'feed back code I mean the code which "is transmitted during "of!" intervals of the master code by virtue of the response of a codeffollowing relay thereto; At location F, the code transmitters will be operating since contact of relay 3ED remains closed, and 75 code will therefore be supplied to section 2 by virtue of the operation of relay IWCflPB... The '.l5 code operating circuit for this r'elayinciudes contact 65 of code transmitter 1561?, back contacts 88 and}! of relays IGOR/and lEHR (now deenergized because section 3 is occupied), and front point 'of contact I of relay 3ED. Relay 2ETR at location E will follow the code and will energize the decoding transformer IEDT so that an impulse output will be delivered from the impulse windinglw for intermittently energizing the relay 2ECTPR. The circuit for relay IECI'PR extends from one terminal of winding IW, bac'k'contacts 61, 33, and 28 of relays IEBSR, 2EHR, '2EHSR, and front contacts 21 and 29 of relays. 2EBHSR and IWTR, to relay 2ECTPR and the other terminal transmits the feed back code through section 3 during the oil period of master code, as prev'iously described. Relay 3WTR will follow the 75 feed back code and in so doing will energize relay 3WCDR, and thuscause relay 3WBSR. to release. The opening of front contact 38 of relay lWBSR will deenergize the code transmitters and cut off the master code at location G. Absence of master code in section 3 will cut off the master code in section 2, since the COR relayis energized, action of which is described later, so that the track circuits of the single track stretch will all be deenergized. At the same time, the traffic light EB on the oilice panel will go out," indicating that the system has been deenergized and is ready for an opposing move, if

desired. I

As long as the train remains in the single track stretch or as long as the eastbound headblock signal ESD is cleared, the reverse code is cut off from section 3 so that relay 3WBSR remains energized and the master code is being supplied, in -readiness for the clearing of the section by the train. A following move can be made at any time cuts oil the feed back code.

by the operator again clearing his signal lever ESL and pressing the code starting button (not shown). The second clearing of the signal lever Consequently, as long as any train is in the single track stretch, the master code cannot be'cut off because of the absence of reverse codelto perform the deenergizing function.

Use of the feed back code to restore the stretch to its normally deenergized condition is an important feature of my system and I shall now explain this feature more'in detail. As pointed out hereinbefore, transmission of the steady energy impulse to location G when the eastbound trafllc direction is being established causes the pick-up of relay 3WBSR at the exit end, thus causing master code to be cascaded to the entrance end for clearing the entrance signal. However, feed back code is. not transmitted from the entrance end E to the exit end G until after the train enterST'.

and progressively vacates the sections: of the stretch. Since feed back code must first be re vacates the stretch;

' closed to complete the pick-up circuit.

ceived at location G before relay SWBSR can be released to out 01f the master code, it is clear that master code will continue to be supplied at location G and it will be impossible to restore the stretch to its normally deenergized condition until the train completely clears the stretch. This is also true during such time as signal IESD is at clear because under this condition, feed back code cannot be supplied at location E because the circuit for relay ZECTPR is open at front contact 27 of relay 2EBHSR. Accordingly, all that is necessary for permitting a following train to enter the stretch is to have the operator clear signal I ESD before the stretch is vacated by the first train. This clearing operation cuts oil? the feed back code at location E thus preventing receipt of this code at location G which prevents the energization of relays SWTR and 3WCDR so that relay 3WBSR does not become deenergized. A duplicate cycle of operations is, of course, effective fer the westbound traiiic direction in which feed back code supplied at location G causes the release of relay 2EBSR once the westbound train At the intermediate location F, I have indicated the control of signals ESF and WSF by showing the control wires (EDG, EHG, and ERG; and WDG, WHG, and. WRG) for these signals which control the clear, caution, and stop aspects, respectively, in the usual and well-known manher. It will be noted that at the intermediate location, the signals will normally be dark, becoming lighted only when a route is established. and the directional stick relay picks up.

Since an eastbound move has been described in detail and since entirely similar operations are bound move, the latter move will be clear without added description.

Looking at the intermediate location F, the initial impulse of steady energy is cascaded beyond this location provided that the relay HR and the directional relay D are both deenergized. The first HR. relay to respond to code picks up the directional relay D for that particular direction. When once picked up, the directional relay remains energized over its stickcircuit until there exists no further need for code. This condition is determined by the cut-out relay -2COR which is energized only when both EHR and WHR relays are picked up at the same time, that is, when both front contacts 69 and 10 of these'relays are Relayv involved in setting up the apparatus for a; west- 200R will accordingly be picked up when the train has passed the next signal, as indicated by the presence of master code in section 3, and no following train is approaching, as indicated by the presence of reverse code. If, after relay 200R is picked up, the, reverse code is cut off because a following move is being made, nothing happens at the intermediate location except that the COR. relay will drop so that the master code will not be cut off. However, if the master code is cut off with relay ZCOR picked up, as will occur whenthe WBSR relay is released, the directional relay will also release so that the intermediate location will become deenergized. Further saving of powercan also be effected by using FSA relays to control the energization of the decoding transformers over their front contacts so that these will be energized only if the associated FSA relay is picked] up.

In the event of failure of the C, T. C. control equipment, the system of Fig. 1 remains operable under manual control, forwhich purpose the push 'buttons FBI and PB2 at location E have been provided. By depressing push button PBI at the 7 headblock location, relay 2EHSR. will be picked up over an'obvious circuit, thus initiating the impulse of steady energy, as in the case of C. T. C. control, which results eventually in the clearing of the headblock signal for that direction, as previously described. If the block is already set up for a move in the opposite direction, relay 2EBSR will be picked up and a suitable lamp at location D can be used to give a warning that this is the case. The purpose served by the push button P32 is to cancel locally the manual set-up in the event that it is desired not to proceed with the route which has been set up.

Summarizing the basic operation of the system shown in Fig, 1, it will be noted that with the system normally deenergized and unoccupied, operation of a lever at the control office causes selective energization of a traflic direction relay at that field station which is located at the new entrance end of the stretch. Pick-up of the traffic relay.

closes a momentary circuit which results in the transmission of an impulse of steady energy from the entrance to the exit end. Receipt of the steady energy impulse at the exit end provides an indication at the oflice that the stretch is unoccupied and results in the application of master code to the exit end of the stretch. This code is cascaded to the entrance end and when there received permits the entrance signal to clear. This code also results in the pick-up of the proper directional stick relay at an intermediate location. As each track section is cleared by the train, master code is applied thereto at the leaving end (the directional stick relay now being up) and this results in the application of feed back code at the entrance end'of the stretch. The feed back code is relayed over the track sections as these become vacated and thus follows the train and causes cutting off of-the master code at the exit end when the train passes completely out of the stretch. Absence of master code at the exit end results in the deenergization of the track at that end. The deenergizin action is cascaded to the entrance end so that the system is restored to its normally deenergized condition in preparation for a following move or a reversal in the trafiic direction;

Referring now to the system shown in Figs. 2a and 2b, the operation ofthis system is similar to that described for Figs. 1a, 'lband 10 with the exception that advance pick-up stick relays are used at intermediate locations to provide for following moves, instead of the usual directional stick relays shown in Fig. 1. As in that figure,

movement of lever ESL to the R'position (for an eastbound move) results in the transmission of a codewhichenergizes terminal and picks up the traflic relay SEHSR, followed by the pick-up of relay SECTPR. The latter relay applies an impulse of steady energy to section 5 during the release interval of relay SEBHSR. The steady energy picks up relay EW'IR at location L, closing front contact H which applies steady energy to ..Master code of the 75 code rate is now applied to section I, causing relay IEHR to pick up and to apply code to section 6 which results in 180 code being repeated into section 5. The 180 code causes the eastbound'headblock signal ESJ to clear, so that the train may now enter the single track stretch.

After the train progresses into section and approachess'ignal EL, the eastbound approach relay 5EAR will pick up and willenergize the approach stick relay 5S (relays @EHR. and BED having become previously energized due to the.

presence of master code at location L). The pick-up circuit for relay 58 includes front contacts l4 and of relays SEAB and GED. Oncepicked. up, relay 5S remainsen'ergized after the tact 8| of relay S, back contact 82 of relay GEHR,

and front contact 83 of relay BED.

A similar operation will take place at location M when relay SEA-Rpicks up. due to the approach of the train, resulting in the pick-up of the approach stick relay 6S and the application of '75 code to section 6. As soon as section 6 is vacated,

the pick-up of relay GEHR at location L will cause 180 code to be supplied to section 5 over the front point of contact 82. is similar to that described in detail for Fig. 1 and need not be repeated. For simplicity, the apparatus at the headblock locations of Fig. 2 has not been shown as completely as in Fig. 1, but it will be understood that similar apparatus may be used in Fig. 2. v

In describing my invention, I have made-use of direct current track circuits and have used but two codes, namely,'having 75 and 180 impulses per minute. My invention is obviously adaptable to alternating current track circuits and to the use of either a smaller or a larger number of codes which can differ in character from the particular '75 and 180 codes which I have chosen for purposes of illustration.

It will be apparent from the foregoing that I have provided a safe, flexibl and comparatively simple system of signaling for single track, two direction operation, in which all of the usual control line wires are eliminated and in which the coded track circuits are normally deenergized.

Among the important advantages of the system embodying my invention are the automatic selfrestoring features which eliminate the need for the usual traflic control levers and which sim- The remaining operation means for cascadingsaid impulse over said sections to the exit endto therebycheck unoccupancy of said stretch, means responsive to the receipt of said impulse at the exit end for supplying a signal control code to the track rails at that end, a headblock signal for said given direction,

means fortrans'mitting said code over said sections to said entrance end, and means responsive to the receipt of said code at said entrance end for clearing said headblock signal to permit traflic to enter said stretch. v 2. In combination with a normally deenergized stretch of track over which trafllc may move in either direction, said stretch being divided into I a plurality oftrack circuit sections; means eflective when said stretch is unoccupied for establishing traffic in a given direction including means for supplying a signal control code to the rails at the exit end of said stretch, means for transmitting said signal control code over said sections to th entrance end, ineans responsive to the receipt of said signal control code at said entrance end for governing the entry of traiflc into said stretch, means eifective after said stretch becomes occupied for supplying a feed back code to the rails at the entrance end when the track section at said entrance end is clearedby the train, said feed back code being transmitted progressively over the sections of said stretch as these become vacated by the train, and means at the exit end responsive to, said feedback code and efiective -upon the exit of the train from said stretch for discontinuing the supply of said signal control code to thereby restore said stretch to-its deenergized condition.

3. In combination with a normally deenergized stretch of track over which trafllc may move in either direction, said stretch being divided into supplying a signal control code to the rails at said" plify operation, and the provision of simple means for setting up tramc direction locally from-the headblock location for the given direction in case of failure of the C. T. C. portion of the apparatus. Although I have herein shown and described only two forms .of apparatus embodying my in'- vention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without depart a plurality oftrack circuit sections, means effective for establishing trailic in a given direction including means for applying an impulse of current to the rails at the entrance end of the stretch, means for cascading said impulse over said sections to the exit end to thereby check unoccupandy of said stretch, means responsive to the receipt of said impulse at the exit end for exit end, means for transmitting said signal control code to the entrance end, means responsive to the-receipt of said signal control code at said entrance end forhgoverning the entry'of traflic into said stretch, means for supplying a feed back code to the rails of said stretch in the rear of the 1 train, and means responsive ,to the receipt of said feed back code at said exit end for discontinuing said signal control code to deenergize said stretch after it becomes vacated by the train.

4. In combination with a normally deenergired stretch of track over which trafilc may move in either'direction, said stretch being divided into a plurality of trackcircuit sections, means for establishing traflic in a given direction including means for applying an impulse of current to the rails at the entrance end of the stretch, means for cascading said impulse over said sections to the exit end to thereby check unoccupancy of said stretch, means responsive to thereceipt of said impulse at the exit end for supplying a signal control code tothe rails at said exit end, means for transmitting said signal control code to the entrance end, means responsive to the receipt of said signal control codeat said entrance end for governing the entry of tramc into said stretch, means effective after the stretch becomes occurent to the rails at the entrance end of the'stretch,

pied and th track sectionat the entrance end is cleared for supplying a feed back code to the rails of such track section, and means for transmitting said feed back code in the rear of the train after the train vacates each successive section in turn, and means responsive to the receipt of said feed back code at said exit end for discontinuing said signal control code to thereby cause deenergization of said stretch following exit of the train therefrom.

5. In combination with a stretch of track over which traific may move in either direction, said stretch being divided into a plurality of track circuit sections, a traflic direction relay at'each end of the stretch for controlling trafilc entering at the respective end, manually controlled means effective for selectively operating one or the other traffic direction relay in accordance with the direction of traflic being established, means efiective when a traihc direction relay is operated for supplying an impulse of current to the rails at the associated entrance end of the stretch and cascading said current impulse over said sections to the exit end to check unoccupancy -of the stretch, a headblock signal at said entrance end,

. means controlled by said impulse when received rection relay in accordance with the direction of trafiic being established, means effective when a trafiic direction relay is operated for transmitting an impulse of current over th trackrails from the associated entrance end of the stretch .to the exit end for detecting unoccupancy, a, head block signal at said entrance end, means at said exit end responsive to said impulse of current for transmitting a signal control code over the track rails from said exit end to said entrance end, and means responsive to the receipt of said signal control code at said entrance end for clearing said headblock signal.

7. In combination with a stretch of track over which traffic may move in either direction, eastbound and westbound tramc direction selecting means at the respective entrance ends of said stretch, means for selectively operating said eastbound or westbound direction means to thereby establish eastbound or westbound trafiic conditions over said stretch respectively, means effective when either of said selecting means is operated and said stretch is unoccupied for trans= mitting an impulse of current over the track rails from the associated entrance end to the associated exit end of the stretch for detecting unoccupancy, means at the associated exit end responsive to said impulse of current for transmitting a signal control code over the track rails from said exit end to said entrance end, and tramc governing means responsive tothe receipt of said signal control cod at said entrance end. v

8. In combination with a stretch of track over which trafllc may move in either direction, a normally deenergized traffic direction relay at the entrance end of said stretch for a given direction of traflic movement, manually controlled means for energizing said traflic direction relay to establish trafiic in said given direction, means effective when said trafiic direction relay is energized and said stretch is unoccupied for transmitting an impulse of current over the track rails from said entrance end to the exit end of the stretch for detecting unoccupancy, means at said exit end responsive to said impulse of current for transmitting a signal control code over the track rails from said exitend to said entrance end, and means responsive to th receipt of said signal ,control code at said entrance end for governing the entry of trafilc movin in said given direction into said stretch.

9. In combination with a stretch of track over which traflic may move in either direction, said stretch being divided into a plurality of track circuit sections, a trafilc direction relay at each end of the stretch for controlling traffic entering at the respective ,end, manually controlled means governed from a control ofiice and effective for selectively operating one'or the other trafiic direction relay in accordance with the direction of traflic being established, means efiective when a traflic direction relay is operated for supplying an impulse of current to the rails at the associated entrance end of the stretch and cascading said current impulse over said sections to the exit end to check unoccupancy of the stretch, a

headblock signal at said entrance end, means controlled by said impulse when received at the exit end for cascading'a signal control code from said exit end over said track sections to said entrance end, means responsive to the receipt of said signal control code at said entrance end for clearing said headblock signal, and emergency manually controlled means at said entrance end efiective for operating the traflic relay at that end so as to clear said headblock signal if said stretch is unoccupied and so to permit traflic to enter said stretch.

10. In combination with a stretch of track over which traffic may move in either direction,- a traific direction relay at the entrance end of said stretch for a given direction of trafiic movement, manually controlled means governed from a control ofiice for energizing said traffic direction.relay to establish trailic in said given direction, means eiiective when said trafiic direction relay is energized and said stretch is unoccupied for transmitting an impulse of current over the track rails from said entrance end to the exit end of the stretch for detecting unoccupancy, means at said exit end responsive to said impulse of current for transmitting a signal control code over the track rails from said exit end to said entrance end, trafiic governing means responsive to the receipt of said signal control code at said entrance end, and emergency manually controlled means at said entrance end efiective forv energizing said tramc direction relay to thereby establish trafiic in said given direction.-

11. In combination with a stretch of track over which traflic may move in either direction, a trafllc track rails from said exit end to said entrance end, traflic governing means responsive to the receipt of said signal control code at said entrance end, and emergency manually controlled means at said entrance end effective for energizing said tramc direction relay to thereby establish trailic in said given directlon.

12. In combination with a normally deenergized stretch of track over which trafllc may move in either direction, said stretch being divided into a plurality of track circuit sections,trafiic direction control means, means governed by said traific direction control'means for transmitting rail current of a master code over said sections from the exit end to the entrance end of said stretch, means responsive to the receipt of said each section governed inresponse to the receipt of said more restrictive master code over the associated section for permitting a following train move, means automatically eifective when the.

last section is cleared by the train and the stretch is then unoccupied by a iollowing train for supplying rail current of a feed back code to said last section, and means responsive to the receipt of said feed back code over said last section for discontinuing the supply of said master code to said last section and in turn to theremaining sections of said stretch and so restoring said stretchto its normally deenergized condition.

master code at said entrance end for governing the entry of traflic into said stretch, means efiective as eachsectionis cleared by the train for supplying rail current of a master code at the exit end and rai1 current of a feedback code at the entrance end 01' each such section, and means controlled by said feed back code automatically effective when the train leaves said stretch for discontinuing the supply of said master code at said exit end so as to discontinue-the supply of I means responsive to the receipt of said master code at said entrance end for governing the entry of traiilc into said stretch, means eiiective as each section is cleared by the train for supplying rail current of a master code at the exit end and rail current of a feed back code at the entrance end of each such section, and means controlled by said feed back code automatically effective when the trainleaves said stretch for discontinuing the supply of master and feed back code throughout the stretch to thereby restore said stretch to its normally deenergized condition.

14. In combination with a normal deenergized stretch oi railway track, manually controlled means for transmitting rail current of a master codeirom the exit end to the entrance end oi said stretch, trafilc governing means responsive to the receipt of saidmaster code at saidentrance end, means responsive to occupancy of said stretch for supplying rai1 current of a feed back code at the entrance end of said stretch, and means controlled by said feed back code automatically efiective upon exit of the train from said stretch for discontinuing the supply of said master and feed back code to thereby restore said stretch to its normally deenergized condition.

15. In combination with a normally deenergized stretch of track, said stretch being divided into a plurality of track circuit sections, means for transmitting rail currentoi a master code over said sections from the exit end to the entrance end of said stretch, trafllc governing means responsive to the receipt of said ma ter code at said entrance end for governing the entry of a train into said stretch, means effective when the train so I passes from one into another'ot said sections for discontinuing the previously applied master code in said one section and supplying to'said one sec-' tion a more restrictive master code unt'il said other section is cleared by the train, a signal for 16. In combination with a normally deenergized stretch oi! track over which traffic may move in either direction, means for establishing trafllc in a given direction over said stretch including means for transmitting an impulse of current over the rails from the entrance end to the exit end to check unoccupancy of said stretch, means responsive tothe receipt of said impulse at said exit end for transmitting rail current impulses or a master code from the exit end to the entrance end of said stretch, means responsive to the receipt of said master code at the entrance end for governing the entry of trafllc into said stretch, means effective after said stretch becomes occupied for iollowing the train with current impulses of a feed back code transmitted to the rails in a the rear thereof, and means responsive to the receipt of said feed back code at said exit end when the train passes out of the stretch for cutting of! said master code to restore said stretch to its normally deenergized condition. 17. In combination with a stretch 0! track over which traflic may move in either direction, said stretch being divided into a plurality of track circuit sections, means for establishing trafilc in a given direction over said stretch including means for cascading a single impulse of current over the rails from the entrance end to'the exit end oi! the stretch to check unoccupancy thereof,

means responsive to the receipt oi! said impulse at said exit end for transmitting, current impulses of a signal control code over the rails from said exit end to the entrance end of the-stretch, and traflic governing means responsive to the receipt of said signal control code at said entrance end,

18. In combination with a stretch of track over which traflic may move in either direction, means for-establishing traflic in a given direction over said stretch including means for transmitting uncoded current over the rails from the entrance end to the exit end of said stretch to check unoccupancy thereof, means responsive-to the receipt of 'said uncoded current at said exit end for transmitting coded current over the rails from said exitend to said entrance end of the stretch, and trafflc governing means responsive to the receipt of said coded current at said entrance end.

19. In combination with a stretch of track over which traflic may move in either direction, means for establishing traflic in a given direction over said stretch including means ror transmitting uncoded current for a predetermined time interval over the rails from the entrance end to the exit end of said stretch to check unoccupancy thereof, said predetermined time interval being sumcient to permit said uncoded current to be received at said exit end, means eflective it and only it said uncoded current is received at said exit end for transmitting coded current over the rails from said exit end to said entrance end of the stretch,and trafllc governing means respon sive to -'the receipt of saidcoded current at said entrance end.

20. In combination with a normally deenergized stretch of track over which trailic may move in either direction, said stretch being divided into a plurality of track circuit sections, manually controlled means eifective when energized for supplying an impulse of current to the rails at the entrance end of said stretch, means for bound directional stick relay, a cut-out relay energized when and only when both said code detecting relays are energized, and a stick circuit for each of said directional stick relays including a back contact of said cut-out relay.

22. In combination with a stretch of track over which trafiic may move in either direction, said stretch being divided into a plurality of track circuit sections, a trafilc direction relay at each cascading said impulse over said sections to the 10 .end of the stretchfor controlling afi c entering at the respective end, manually controlled means exit end of the stretch to check unoccupancy thereof, means at theexit end controlled by said impulse for transmitting rail current impulses of a master code over said sections from said. exit end to said entrance end, means responsive to the receipt of said master code at said entrance end for governing the entry of trafiic into said stretch, means eifective when the first section at said entrance end is cleared by the trainfor supplying current impulses of a feedback code to the rails of said first section, means for transmitting said feed back code" over said sections to the exit end as the train progressively clears said sections, control means at said exit end operated in response. to receipt of said feed back code for deenergizing said stretch when the train passes completely out of the stretch, and means effective upon a second energization of said manually constick relay adjacent the junction of said two sections, selectively responsive traflic direction control means for supplying coded rail current at the eastbound exit end of said right-hand track circuit for establishing eastbound traffic direction over said sections. and for supplying coded rail current at the westbound exit end of said left-hand track circuit for establishing westbound traflic direction over said sections, means responsive to the exit of a train'from one or the other section for supplying coded rail current to the vacated section, an eastbound and a' westbound code detecting relay energized in response to the presence of coded rail current in said right-hand or'said left-hand track circuit respectively, a pickup circuit for said eastbound directional stick relay including a front contact of said eastbound code detecting relay and a back contact of said westbound directional stick relay, a pick-up circuit for said westbound directional stick relay including a front contact of said westbound code detecting relay and a back. contact of said eastfor selectively operating one or the other trafiic direction relay in accordance with the direction of traflic being established, means effective when a traflic direction relay is operated for transmitting an impulse of current over the rails, from the associated entrance end to the exit end of the stretch for checking unoccupancy thereof, means efiective when said impulse is received at the exit end for transmitting rail current impulses of a signal control code from said exit end to said entrance end, control means responsive to thereceipt of said signal control code at said entrance end for governing the entry of traffic into said stretch, a normally deenergizedadvance pick-up directional stick relay adjacent the junction between two adjoining sections, means effective when the train approaches within a predetermined distance of said junction for energizing said directional stick relay, and means effective when said directional stick relay is energized for supplying a signal control code to the rear one of said two sections to cause response of said control means and so permit a following train to pass over said stretch.

23. In combination with a normally deenergized stretch of railway track, said stretch being divided into a plurality of track circuit sections, means for transmitting an impulse of rail current from the entrance end to the exit end of .said stretch to check unoccupancy thereof, means at the exit end effective when said impulse is received at that end for transmitting rail current impulses of a signal control code from said exit end to said entrance end, control means responsive to the receipt of said signal control code at said entrance CRAWFORD E. STAPLES.

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