US2403085A - Coded track circuit signaling system - Google Patents

Description

July 2, 1946. -r. J. JUDGE CODED TRACK CIRCUIT SIGNALING SYSTEM 1941 14 Sheets-Shae}. 1-

Filed Feb. 14

INVENTO y 1946. T. J. JUDGE CODED TRACK CIRCUIT SIGNALING SYSTEM Filed Feb. 14, 1941' 14 Sheets-Shee t 2 O I wylg wl ATroimEY INVENT NE J XE KEN? \ I l l I I I I I a 0mm 14 Sheets-Sheet 3 N. mi W92 Tu I T. J. JUDGE Filed Feb; 14, 1941 Haw J V 5 CODED TRACK CIRCUIT SIGNALING SYSTEM v I rmw I I l l 54 3 3 July 2, 1946.

. .1 8 "T KIA him g l u ML .n I v W a w v Illu'llll IL km UA E July 2, 1946. T. J. JUDGE CODED TRACK CIRCUIT SIGNALING SYSTEM Filed Feb. 14, 1941 14 Sheets-Sheet 4 INVENTO :4 ATTORN-EY "Jill 2, 1946,

T. J. JUDGE CODED TRACK CIRCUIT SIGNALING SYSTEM Filed Feb. 14. 1:941 14 Sheets-Sheet 5 y 2, 1946- 'f T. J. JUDGE v CODED TRACK CfRCUIT SIGNALING SYSTEM l4 Sheets-Sheet 6 so? NE? NW@ im m 5% infi NHQQL m Filed Feb. 14, 1941 RHT INVENTOR 7152 July 2, 1946. T. J. JUDGE I v CODED TRACK CIRCUIT SIGNALING SYSTEM 14 Sheets-Sheet 7 INVENTOR4I BY MW W ATTORNEY Filed Feb. 14, 1941 July 2, 1946.

T. J. JUDGE CODED TRACK CIRCUIT SI GNAL ING SYSTEM "Filed Feb: 14, 1941 14 Sheets-Sheet 8 N mam 3 I 165. mc En 296 :6 mnm .QWwE

"Jul 2, 1945.]

1-,,1. JUDGE CODED TRACK CIRCUIT SIGNALING S YSTEM Filed Feb. 14, 1941 14 Sheets-Sheet 9 NTO ATTORNEY ou qr fl July 2, 1946. T. J. JUDGE CODEDTRACKflIiiCUIT S IGNALIN G SYSTEM 14 Sheets-Sheet 10 INVENTOR f ATTORNIEY J BY. LU

Filed Feb. 14, 1941 y 1946- T. J. JUDGE- CODED TRACK CIRCUIT SI GNALING' SYSTEM 14 Sheds-Sheet 11 Filed Feb. 14, 1941 ATTORN'EY m FY S 14 Sheets-Sheet l5 T. J. JUDGE Filed Feb. 14, 1941 July 2, 1946.

CODED TRACK CIRCUIT SIGNALING SYSTEM July 2, 1946. T. J. JUDGE CODED TRACK CIRCUIT SIGNALING SYSTEM 14 Sheets-Sheet 14 1 wm fiI. m MW Tmwnn l a RE 1 .QGMMWJ N QW m m H. @m w WBQL B m 3 I F ATTORNEY Patented July 2, 1946 Thomas J. Judge, Rochester, N."Y., assignor to General Railway Signal Company,'Rochester,-

Application February 14, 1941, Serial No. 378,961

31 Claims. (01. are-33y The present invention relates to railway sig- W naling systems and more particularly to a rail-'- way signaling system of the absolute-permissiveblock type.

For economic reasons it is important to keep the number of line wires along the railway track to a low number. In accordance with the pres ent invention it is proposed to obtain all of the facilities and speed of operation of the signal controls heretofore enjoyed in railway signalused through'the passing siding. In order to obtain these facilities it is proposed in accordance with the present invention to employ only twoline line wires extending from each signal location to the next signal location through both single track sections and passing sidings, and to employ a relay or other electro-responsive device at each end of such pair of line wires to afford double use of these line' wires. It is proposed to employ a source of current at eachend of such pair of line wires and to provide synchronously operated contacts on these electro+ responsive devices near the end of each of the pair of line wires, for the purpose of at one instant connecting the relay at one end'of these ing systems of the absolute-permissive-blocl;

- track section.

line wires to the. source at the other end and Another feature of the present invention resides in the employment of an inverse code sometimes called an' ofi code for the purpose of transmittingadditional information over a track circuit in the direction from the track relay end toward the track batt'ry'end thereof; Another feature of the present invention resides in the provision of signaling circuits whereby the pres-' ence ofy-a-train on one passingsiding is manifasted byfthe displayof a caution signal at the next passing siding in advance of 5 the train. This lattenfeature is -particular1y desirable where the [single track section is so short that double braking" distance is not availablebetween two opposing intermediate signals along such single Other objects-purposes and characteristic features of the present invention will in part be described hereinafter and will in part be obvious from the accompanying drawings, in which:

end constitute'one signaling system embodying l the present invention;

Fig. 2 illustrates the positions that'the contacts of the search-light signal assume under clear, cautionand stop :traffic conditions, respectively;

trate the signal-indicationsand their conditions of illumination when a train occupies various points along the trackway;

"Figs. 4A, 4B; 4C, 4D and 4E illustrate .a modified form ofthe present invention; 7

Figs. 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H and 51 illustrate the various signal indications fort he system shown-in Figs. 4A; 4B, 4C, 4D, and 4E I with an eastbound train'occupying various'points for manifesting the presence of a train in the;

posite directions over the pair of line wires above mentioned and located adjacent the track circuit.

along thetrack;

andGK illustrate the various signal indications and their conditions of'illurnination when a west moving-trains make a meet o n-a passing siding.

1 i *1 structztra Referring' to' Figs; 1A to n; inclusive, thetrack rails'fl 0 have been'shownf divided-into'sectionsby insulating joints I If to insulate "adjacent "track sections fromeach other.

Therailway signaling system illust'rated' includes apassing side A; a passing siding B, asingle track section 0 connecting the -two passingsidings tog game and a por'tiono'f another single track sectio'nL Theva'rious signals havebeen designated S tently closing av contact.

. 3 with a suffix number to distinguish these signals from each other, the signals Sill, vSlllA, Sll, SIZ, SIB, SM, SIT, Sl8, SIB, SI9A, S20, SZBA, S2I and S23 having been illustrated. Each of these signals may constitute a signal of either the semaphore type, the multiple unit light signal 7 type, or the multiple aspect searchlight signal type, but for convenience only the search-light type signal has been illustrated in the drawings.

This search-light type signal is preferably of a construction such as illustrated in the patent to 1 Field, No. 2,097,785, dated November 2, 1937. The

polar windings of these search-light type signals have been designated W withasuflix number cor-y track relays being provided with a distinctive identifying number corresponding to the track circuit withwhich they are associated and each of I2CPR, back contact H of the opposing direc tional stick relay I3S, winding of the home-distant relay l2I-ID, front contact 22 of the signal repeater relay MYGP and to the other terminal of said source of current. Under caution traific conditions the home-distant relay l2I-ID is controlled through a circuit similar to the one just traced but is energized by current of negative polarity. This circuit includes the same contacts as the contacts just recited except that the "contacts H and 22 of the signal repeater relay MYGP assume their retracted position and exceptfor the fact that the front contact 24 of the directional. stick relay MS is included in series in this circuit. The coding relay IECPR, as con- Ventionally shown, is energized intermittently through a front contact28 of suitable code creatthefre'maining relays being provided with a distinctive identifying number corresponding to the identifying'niiniber of the signal which the homed istant relay in question controls. Thereference characters CT. and CPR with a suitable sufiix and the relay to which it is assigned designate suitable code creating apparatus for intermit- Where this letter CT or CPR has associated with it the number;75 signifies that the contact is closed approximately seventy-five times per minute, and where this 1 letter CT or CPR has associated therewith the number 120 signifies that its associated contact intermittently closes one hundred and. twenty times per minute. These code creating devices may be of any suitable constructionand are preferably operated electrically and continuously. It is believed unnecessary to describe the circuits associated with all of the signalsillustrated, and

'iorconvenience the circuits. associated with the signal S12 and some of the circuits controlling the signal SI! only will bepdescribed. and like parts of remaining signalcircuits willbe assigned like reference characters having distinctive exponents, prefixes or sufiixes.

I Referring to Figs. 13 and 1C of the drawings,

the signal Sl2 is a signal of the search-light type having a polarized mechanism controlledby the T winding WIZ; This winding; WIZ is energized by current. ofnormal polarity. under normal clear traiiic conditions, as illustrated. This energizing circuit extends from the terminal of. a suitable source of current through the polar contact I2 of therelay IZI-lD assuming its righthand position, the front contact [3 of this same relay, the winding Wl2, the neutral contact {4 i 7 and the polar contact. I5 assuming its righthandp osition and to the other terminal of this same source of current. This home-distantf relay IZHD is under normal clear traflic 1" conditions, as illustrated, energized to its right- {'T.

hand. polar position through the following circuit beginning at the terminal of a suitable source of current, front contact! 1 of the signal repeater relay MYGP, front contact [8 of the track relay n ntact. 19 or the-trackrepeater-re-i- *lay'l2FBP, front contact 20 of the coding relay ing apparatus 'IBCT at a code rate of '75 impulses per minute. It is thus seen that the home-distant relay [2HD cannot be energized to its left-.

hand polar positionunless the directional stick relay for the next signal in advance assumes its energized position.

Itis, of course, understood that the coding. relay 'IZCPR is intermittently energized seventyfive times per minute andthat when it assumes'its energized position 'the track circuit extending from thefsignal sm to the signal sea; is closed.

This track circuit, includes thetrack battery Bit, theapproach relay AlZT, the coding contact 25 and the track relay [2T in series. This track relay [2T will of course be intermittently picked up at the ratev of seventy-five times per minute in substantial synchronism with the coding relay IZCPR. so long as the track circuit is not occupied by a train. 'The intermittent picking up of the track relay [21' through the medium of its front contact 26 intermittently applies energy tothe slow dropping track repeater relay IEFP so as to cause it to assume its energized position continuouslyand in the same manner this contact 26 as itintermittently assumes'its retracted position willl'intermittently apply energy to the inverse track repeater relay I2FBP through the medium of frontc'ontac'til' of the code repeater'relay IZFP, tocause this relay I2FBP to continuously assume its energized" position. iThe track repeater relay l2FP is. in fact an on pulse repeater relay whereas theytrack repeater relay I2FBP is anfo pulse repeater relay which alsochecks the presence of on impulses; and therefore 6011-:

stitut'es a relay that can be up continuously only ifthe trackrelay [2T i's'intermittently'picked up. The net resuIt is that the track repeaterrelay I ZFBP assumes its energized position only if the track circuit is intermittently energized. V

Thedi'rectional stick relay [2S is provided with a pick-up circuit including the 'fro-nt contact 30. r

of theapm'oach track repeater relay Ai3TP and a front contact 3P of," the caution-clear signal,

repeater relay IZYGP. This directional stick relay IZS is also provided with two stick circuits, one; including the back contact 3'i' 1of the signal repeater relay I ZYGRthe other including the front contact 33 of the approach track repeater.

relay. A .I3.'IP, and both including. the stick contactSZl of this directionalstick relay. l2'S-. "The signallrepeater relay l2YGP is normally energized through the back. contact. 30 of the relay A1l3TP' and. the clear. contact. 33 ofthe searchlight mechanism. ofsignal S l2, and under caution traific conditions is energized in series gthrough this back cemaetsew andthe-eontacts; are and 34 of this signal Si 2 both assuming theletthand caution position (see. also Fig. 2 Attention is at this time directed to Fig. 2 which illustrates the positions assumed by the contacts 33 I and 34 under clear, caution and stop traffic conditions, respectively.

The app-roach home relay IIAHD (see Fig. 1C) is controlled by the contacts I1 and 22 of the caution clear signal repeater relay I3YGP in exactly the same manner as the home-distant relay I2HD is controlled by the contacts I1 and 22 of the caution-clear signal repeating relay MYGP and by the directional stick relays I35 and 14S and the track repeater relay IZFBP. It should, however, be noted that this approach home-distant relay I'IAHD does not directly control a signal but does control the home-distant relay llI-ID, which in turn controls signal S". The normal clear circuit for the home-distant relay HHDmay be traced as follows: beginning at the terminal of a suitable source of current, polar contact 36 of the relay iI AI-ID assuming its right-hand position, front contact 31 of this same relay, contact of the coder 15CTI4,

front contact I9 of the track code repeater relay l4--|'|FBP, back contact |8 of the track .relay I4-I'IT, winding of the home-distant relay HHD, front contact 38 of the approach homedistant relay I'IAHD, polar contact 39 of the relay I'IAHD assuming its right-hand position and to the other terminal of said source of current. 7

Referring again to Fig; 1B of the drawings, as heretofore mentioned the directional stick relay i2S has a pick-up circuit including a front contact 30 of an approach track code repeater relay AISTP. It may be pointed out that this relay AI3TP is normally deenergized (track circuit unoccupied) because there is insufiicient current flowing in the approach track relay AI3T to pick it up when there is no train. in the block. The presence of a train in the block will, however, cause intermittent picking up of the approach track relay A! 3T causing intermittent application of energy to the approach track repeater relay AI3TP through the front contact M of the approach code following track relay AI3T. Since this approach track repeater relay AI 3TP is Short circuited by a rectifier, as conventionally shown, it will not drop away during the periods of intermittent deenergization of the approach track relay Ah'iT. In other words, the approach track repeater relay A! 3T? is continuously deenergized' where the directional stick relay is picked up by I the dropping of a track repeater relay, instead of the picking up of an approach track repeater relay, the contact in the pick-up circuit for the stick relay has been designated 40 with an exponent corresponding to the track relay with which it is associated.

Each of the track switches SwE, SwEB and S-wW is provided with a detector track circuit. The track relays for these detector track circuits have been designated DTE, lDTE-B and DTW, respectively. By referring to the detector track relay DTE (see Fig. 1A) it will be seen that in addition to the contact HI already mentioned this track relay is provided with front contacts 42 43 and The front contact 42 is included in the circuits for controlling the home and I3HD cannot assume an energized position unless both thedetector' track circuit including the track relay DTE and the track circuit including the track relay I3T are unoccupied. In a similarmanner the front contact 43 is included in the energizing circuit for the home-distant relay |lHD,-so that the home-distant relay l IHD cannot be picked up unless both the track circuit containing the track battery 13 and the detector track circuit containing the detector track relays DTE and DTEB are both unoccupied. The other contact is included in series with the front contact 45 of the track repeater relay l3FBP and these two contacts in series are capable of shunting the front contact 24 v of the directional stick relay IDS. These'front contacts M and 45 (see Fig. 1E) are effective to deenergize the home-distant relay I8HD (see Fig. 1D) when there is a west-bound train in the section extending from signal S20 to signal S23 (directional stick relay ZiiS deenergized and its contact 24 open) to cause the signal SIB to assume the stopposition and the signal SM to assume the caution position when a west-bound train passes the signal S23.

As heretofore pointed out the railway signaling systems such as shown in Figs. lA-lE are provided with wayside signals of the search-lightv type such as disclosed in the Field patent above referred to. Each of these signals includes a spectacle having color screens permitting the emission of green, yellow and red light respectively, this light being emitted from an incandescent lamp. These lamps are normally deenergized and are energized only upon the approach of atrain in the approach track section unless the signal is at stop. These incandescent lamps have been designated L with a uffix corresponding to the signal with which they are associated and are each included in an energizing circuit containing an approach lighting contact 46 controlled by a back contact of a signal repeaterv relay, and for convenience all of these contacts have been designated 46 with an exponent corresponding to the signal repeating relay with which they are associated. These relays GP and YGP are signal repeating relays in that they. cannot assumean energized position when the associated signal is at stop. They, however, also perform an approach lighting function in that .'.they will also be deenergized when a train'approaches the associated signal. The relay IZYGP is deenergized upon picking up of approach repeater track relay AI3TP due to occupancy of the block extending from signal Sill to SIZ. Attention is directed to the fact that dropping of either the signalrepeater relays IUYGP and'HGP will light all of the three signal lamps LIB, LIOA, and LI 1. This is resorted to so that a train standing on the passing siding (non-track circuited) will have its signal lighted under all adverse traffic conditions. In other "words, these signal repeating relays GP and YGP at times, by dropping, reflect the .ap proach of a train by lighting-the signal and. at other times manifest that the signal i at stop- Obviously, the two ends of the passingsiding include the usual track switches, which are 'presumably hand operated in the present system,

relays IOHD and l3I-ID, respectively, and performs thesarme function in these circuits that the front contact N3 of the --track repeater relay I3FBP performs. In other words,the home relays IOHD track switch withwhich they are associated. .The

1 switch repeater contact 48 'is included in the reference characters having distinctive exponents corresponding to the track switches with which they are associated.

It willbe observed that the directional stick relay HIS is'provided with two pick-up circuits.

The one including the front contact 3| of the clear-caution signal repeating relay. ISYGP and the other including the front contact 3 I of the clear-caution signal repeating relay IBAYGP and both including the back contact H of the detector track relay DTE. It will also be seen that one stick circuit'for relay IDS includes back contact 40 and the stick contact 32 andthat another stick circuit. includes the back contacts-40 31 and 3H of relays-ISFBP, ItYGP, and IUAYGP respectively. This circuit construction is resorted to in order to afforda pick-up circuit for directional stick relay IOS irrespective. of whether the train entering the west end of the single track section illustrated moves off of the main track or off of the side track of the passing siding A. It will be noted that only one of signal repeating relays,v IQYGP or IIiAYGP can .be energized at a time and for this reason. front contact M and 3 I 10A have been provided in multiple for pick-,

ingu-p the directional stick relay "is. The directional stick relays ISS and S are similarly controlled by contacts identified by like reference characters having distinctive exponents.

Under normal conditions of the railway signaling system illustrated the track switche SwE, SwEB and SwW shownin Figs. IA, ID and 1E all assume their normal main track position. A- tention is directed to the fact that the detector track circuits associated with these track switches are of the non-coded type, that is,.the.track relays arev continuously energized so long a the detector track circuitsare notoccupied and assume their deenergized positions so longv as such detector track circuits are occupied. Each ofv the remaining track circuitsillustrated in Figs. l'A to 1E are coded atthe 75 impulse per minute. code rate and during unoccupancy the track relaysof these track circuits pick up and, drop away seventy-five times during each. minute ofcunoccupancy. It will also b'e'noted that all of the coded track circuits except the. track circuits between signals SM. and, SH: and betweentnsignals.

Sl 9 and S20 is provided with an approaclrtrack relay designated AT with a number between these letters each corresponding to'th'e prefixv of the track. relay with. which it is connected in. series. These approach track relays are normally deenergi'zed and are intermittent-1y energized at the 75impulseper minute rate during occupancy of. the track circuit inlwhich they are included.

These approach track relay are. series relays and require a larger than normal track circuit current to pick them up. It will be seen that these approach track relays are only'used for controlling signal repeater relays alsozcontrolled by signal mechanism contacts, andQirBctiOnaL stick; relays, and When soused conformtotheprinciple-ofthe nomes normally closed circuit. It is considered perfectly safe to. control thepicking up of a directional pick up results ina danger aspect instead of a caution aspect; s

As just pointed' out the track circuits throug the single track section are coded at the. '75 impulse per minute code rate, but this is not done .for thepurpose of transmitting a special control over the'track circuititself, but is used primarily to provide a way of operating contacts at both ends of the track circuit intermittently and insynchronism. 'In the system of Fig. 4 it is, however, used to transmit special controls. These contacts have been designated I8 and 20 in the drawings. The contact 20 is a contact on a coding relay which'codes the track circuit, and the contact I8 is the contact on the track relay at the opposite end of the track circuit which, of course, closely follows the operation of the coding contact 25 located at the source end of the track circuit. It will readilybe seen that with the contacts I8 (see Fig. 1A) and 29 (see Fig. 1B) when both energized allow current to flow from right to left through this circuit to pick up the home-distant relay IGHD from a source at the east end of the line circuit, and that if these contacts I8 and 20 are both 'deenergized they allow current to flow from a source at the west end to pick up the horne distant relay I3HD. This alternate use; of the two line wires at a seventy-five times perminute. rate is resorted to for controlling the home and distant relays IUHD vand IBHD, and due to their slow-dropping char acteristics causes these relays IElI-ID and It'll during clear or caution traffic conditions to be maintained continuously energized. In other words, the line circuit performs a double function inthat the contacts I8 and 20 allow the .time

of useof this line circuit to be allotted alternately for the alternate energization of these relays IilI-ID and IS'HD. What has been said in regard to the home-distant relays HEHD and ISHD is also true of all of the other home-distant relays and approach home-distant relays of Figs. lA -lE as well as of the mechanisms M of Figs. 4A-4E.

Fig. 1 operation.Let us now assume that there of the passing siding A' (see ,Figs. 1A and. 3A). The presence of this train will open the circuit for the home-distant relay III-ID at a contact not shown in Fig. 1A but shown in Fig. 1D and designated I8 of track repeater relay 2IFBP. With the home-distantrelay HHD deenergized the signal SH ,is put to stop, as shown by the letter R in Fig. 3A, because the circuit for the control of its winding WII is open at front contacts #3 and I4 of the relay III-ID. With thesignal SII assumingv its stop position its contacts 33 and 34 will assume a stop position as illustrated in the lowermost sketch of Fig. 2

changer contacts of the drawings, and when in such position the circuit for the signal repeater relay ,IIGP is broken, thereby causing this relay IIGP to assume its retracted position and operate its pole- I'l and 22 to the-reverse position, in which position the current through the winding of the home-distant relay I'3I-ID is reversed. so thatthe polar contacts I2 and I5 otthishome-distant relay ISHDJasSUme the left! hand position to cause the current flowing in the winding WI 3 of this signal SI3 to be reversed thereby operating the signal SI3 to caution position in which it emits a yellow signal beam and operates the contacts 33 and 34 to the lefthand or caution position (see Fig. 2) in which position the clear-caution relay I3YGP remains energized as before. In other words, movement of the signal SII to the stop position causes the signal SI3 to assume the caution position, but the next signal in the rear, namely, signal S" remains in its clear position .(see Fig. 3A). In other words, a train whether east-bound or westbound standing on the main track of the passing siding A (see Fig. 1A) is protected against a west-bound train moving in the single track section by a stop signal and a caution signal next in the rear thereof. 7

. The dropping of the signal repeating relay II GP, however, performs another function, namely, the closing of its approach lighting back contact 46 which results in' the illumination of the lamps LII LIIlA and LI I. These three lamps are controlled in multiple because it is desired to illuminate the lamp LIIJA each time either the lamp LII] or LI! is energized. It may be pointed out here that the lamp LIOA is not energized with a train on the side track of the passing siding unless the associated track switch is in its take-siding position.v With the track switch SwE in the take-siding position theswitch box contacts MSwE' and SQSwE are both open placing the signals SIIJ and SH in the stop position but allowing signal SIIJA to reflect traflic conditions ahead and causing .deenergization of the signal repeater. relays IDYGP and II GP, which in turn cause the approach lighting contacts 46 and 46 to be closed to approach light not only signal SIDA but also signals SI!) and SI I.

Let us now assume that the east-bound train on the main track of the passing siding A (see Fig, 1A) advances past the. clear signal SIII, as shown in Fig. 3B. The presence of this train on the detector. track circuit containing track relay DTE (see Fig-1A) causes this detector track relay DTE to assume its deenergized position.

Since this detector track relay DTE has a frontcontact 42 included in the energizing circuit of the home-distant relay I3HD this, home-distant relay I 3HD is deenergized, thereby deenergizing the winding WI3 of the signal SI3 and operating this signal SI3 to its stop position. Movement of the signal SI3 to the stop position causes itscontacts 33 and 34 to assume their left-hand and their right-hand positions, respectively (see lowermost sketch of Fig. 2), thereby opening the circuit for the signal repeater relay I3YGP causing deenergization of this relay. The dropping of the si nal repeater relay ISYGP at its back contact 45 closes an energizing circuit for the lamp LI3 for the signal SI3, so that this signal SI3 will actually emit a red beam signifying danger trafiie conditions to an opposing train. Furthermore, the dropping of the signal repeater relay I3YGP causes operationv of the pole-changer contacts I1 Z2 ,as a result of which the. energizing circuit for the approach home-distant relay I'IAHD (see Fig. 1C) is broken because with the contact 22 of the signal repeater relay. I3YGP in its retracted position the circuit for this approach home-distant relay I'IAHD is open at front contact 24 of. the directional stick relay I3S, this directional stick relay only assuming its picked-up position in the event there is a west-bound train moving in the block between signals sis and SII. With the approach home-distant relay IIAHD now deen- 2) the caution-clear signal repeater relay IIYGP- (see Fig. 10) also assumes its retracted position and closes the signal lighting. back. contactMi for the lamp LI'I of the signal SI'I. Furthermore, dropping of thesignal repeater relay I1YGP causes pole changing of its contacts I1 and 22 and since the front contact 24 of the directional stick relay IIS is open the energizing circuit for the home-distant relay IQHD is broken, thereby causing deenergization of the winding WI 9 for the signal SIS resulting in the placing offthe starting or head block signal SIS inthe stop position. In this connection it should be'not ed that the energizing, circuit for the Winding WIS of the signal SIS includes a switch repeating contact 48 and that if the track switch SwW assumed its take-siding position this contact 48 would be opened but in this case thecontact 493 would be closed as a result of which the signal SISA instead of signal SIB would have been controlled in accordance with trafiic conditions in advance. Movement of the signal SIB to the stop position causes the contacts 331? and 34 within the signal mechanism to assume the stop position as illustrated in I the lowermost. sketch in Fi 2 and thereby cause the cautionclear repeater relay I 9YGPto assume its retracted position. With the relay I BYGP in its retracted position the approach lighting contact 46 is closed lighting up the lamps LIB, LI9. and LISA.

Also, with the signal repeating relay IBYGP in its retracted position its pole- changer contacts 11 and 22 reverse the polarity of thecurrent applied. to the home-distant relay ZIHD (see Fig; 1E). This is true even though the directional stick relay His is in its normal'retractedposition,

This is true because its front contact2 i of this stick relay is shunted by a shunt circuit including the front contact M of the detector track cupied. Should, however thetrain in question pass the opposing signal Sll the signal SZI would be moved to its stop position by reason of. opening of thefrontcontactfi of the track repeater relay IBFBP (contact 24 of relay I9S being open). With the signal S2I now assuming its caution position because the home-distantrelay 2 IHD has been operated toits left-hand polar position (the trainunder consideration still occupying the position illustrated in Fig. 3B) and has pole changed the current flow in the winding WZI, causes the signalSZI to assume the caution position. This operation'of the mechanism. Of the signal SZI to its caution] position, in which both of its contacts 33 and 342 assum their Vii train past the signal Sltl .(see Figs. 1A and 33) causes .a tumble down ofstop signals'to take place throughout theentire single track section resulting in the placing atstop of all of the opposing or west-bound signals- Sl I, 313, Si! and SI9 and further results in putting the. signals S2! and S23 in the caution position. V

Another functionjthat takes place as the eastbound train passes the -signal SHlresides in the picking upof the directional stick relay ills. This j is accomplishedbythe closing of the pick-up circuit including the back contact MD ofthe de. tector relay and including the back contact s ;'or the slow-dropping signal repeater relay 1 IOlAYGP, the front contact 3l .of the slow-dropping signal repeater relay IBYGB and the winding for. this stick rela J'fiS. With the stick relay HlS once energized it is stuck up through a stick circuit including the backcontact 48 of the detector track relay DTE and the stick contact :32 inseries. H

As the east-bound train advances past the op- 1 posingsignal SI I (see Fig. 30) it results in continuous deenergization of the track relay I3T, which in turn results in con-tinueddeenergiza- ;tion or the home-distant relay HJHD which was formerly deenergized by reasonof open contact 42 of the detector trackrelay DTE included in series in its energizing circuit. With the track 1 relay I3' I' continuously deenergized the track re.- peater relays l3FP and I3FBP are continuously deener'gized. .With the track repeater relay I3FBP in its'retracted position and withits back con- ;tact 401 closed a supplemental stick circuit for therdirectio'nal stick relay IDS i closed which stick -circuit includes the back contact 49 of the track, repeater relay IBFBP, the back contacts 3 and3l 10A of the signalrepeater relays tYGP and IUAYGP in series, and the stick-contact 32 As the east-bound train under consideration continues its movement between the signals SH and S12 (see Fig. 3C) the directional stick relay IGS will remain stuck up through the supplemental stick circuit heretofore traced, the original stick circuit through back contact HI having been opened. Movement of the east-bound train between the signals SH and SIZ as above pointed out results in the intermittent picking up of the approach relay AIST which in turn results in the repeater approach relay Ai3TP assuming its energized position continuously The front contact 39 of the approach relay Al3'IfP now closes apic'k-up circuit for the di- .of, this directional stick relay MS. Although thesignal SIZ had its mechanism in the clear position under the assumed trailic condition under consideration as illustrated in Fig. 3B,"this signal was then a dark signal, its associated approach li hting contact 46 of relay IZYGP being open.

With the train now advanced past opposing signal SH to a position as illustrated in Fig. 3C theapproach track relay AIBT is intermittent y pickedup to hold up repeater track relay AISTP continuously. This results by Op 0f i back contact-i0 indropping of relay IZYGP and by closing of back contact 46 in the lighting of sition'its frontclosed contact 24 applie cauition energy through-a branch c rcuit in multiple .withthis'front contact M to the hornedistant relay next in the rear,- which is not shown ID of the drawings.

in Fig. 1A but1'has been designated IBHD in Fig; '1

rectional stick relay I25. This directional stick relay IZS is then stuck up'through a stick circuit heretofore traced in connection with the directional stick relay IDS. Also, the continuous picked-up condition of approach repeater track relay AI3TP opens its back contact 35 and drops the caution clear signal repeater relay I ZYGP and the closure of its back contact 46 closes an energizing circuit for the lamp LIZ.

:As the east-bound train now passes the signal SIZ (see Fig. 3D) it will result in the continuous picking up of the approach repeater relay AIZTP. Since, however, the signal S|3 assumed its stopv Position, in view of the tumble-down which took place when the train passing signal Sill, and its repeater relay I 3YGP assumed its retracted position the directional stick relay 138 is not picked up. The presence of this east bound train in the track section between the signals SH and SM (see Fig. 3D), however, results in continuous deenergization of the track relay 121 which in turn results in continuous deenergization of the track repeater relay I2FP and IZFBP, so that the front contact I9 of the track repeater relay l ZFBP is opened thereby resulting in the continuous deenergization of the home-distant relay I 2HD which in turn results in putting the signal SIZ in its stop position all for reasons heretofore pointed out. track repeater relay IZFBP' continuously deenergized the opening of its front contact 40 and deenergizatlon of the cautionclear relay MYGP causes the approach lighting-contact 46 in the circuit for lamp M4 to be closed and the signal SM to become lighted as shown in Fig. 333.

With the signal SI 2 in the stop position its caution-clear repeater relay IZYGP is deenererized. so that its approach lightin contact 46 ,is' closed to light the signal lamp L12 so longras the signal Sl2 remains at stop and irrespective of the position assumed by the contact 3!] of track repeater relay AlSTP. This dropping of the clear-caution si nal repeater relay IZYGP at its back contact 3! also closes a supplemental stick circuit for the directional stick relay 128. As soon as the rear end of the train passes the signal S12 (see Fig. 3D) the track relay IST will again intermittently respond to the coded current app-lied to the track circuit in which it is included y the contact 25 of the coding relay, I3CPR. Intermittent picking up of the track relay I3T causes the track repeater relays I3FP and |3FBP to be held up continuously. The picking up of thislatter track repeater relay I 3FBP by the closing of its contact I9 allows caution current to flow to the home-distant relay IIJHD through a circuit including the front contact 24 of directional stick rela IZS, the front contact I 9 of relay ISFBP and the front contact 42 of the detector track relay DTE, as a result of which the signal SID may assume the caution position. This Also, with the

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