US1626006A - Railway-traitic-controlling apparatus - Google Patents

Description

1,626,006 Aprll 26 1927- R. A. McCANN RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 23, 1924 2 Sheets-Sheet. 1

INVENTOR:

M WV

2 1927. Apnl 6 R. A. M CANN RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 23. 1924 2 Sheets-Sheet 2 INVENTOR.

KQI

Patented Apr. 25, 1927.

UhliTE STATES OFFICE.

RONALD A. MCCANN, OF $XVISSVALE, PENNSYLVANIEK, ASSIGNOR TO THE UNION OF PENNSYLVANIA.

.QSYLVANIA, A CORPORATION RAILXVAY-TRAFFIG-CONTROLLING APPARATUS.

Application filed January 23, 1824.

hi invention relates to railway traliic controlling appara us. and particularly to apparatus of the type comprisingtrain carried governing means received troni the trackwav. More particularl my invention relates to the traclnvay portion of such apparatus.

I will describe one fOlIll of tracltway apparatus embodying my invention and will then point out the novel teaturcs thereof in claims.

In the accompanying drawings. Figs. 1 and 2, when placed end to end with Fig. 2 on the right constitute a dism-amniotic view showing one form of railway trallic wntrolling apparatus cmhodvingmv invcntion.

Referring to the drawings. the reference characters 1. and l" designate the track rails of a stretch of a railroad over which trattic normally moves in both directions. This stretch is provided at its left hand and right hand ends with passing" sidines X and X respectively. It is understood that a number of portions of track such as shown in the drawing could be placed end to end to form a complete system consisting of stretches of single track separated by passing; sidings. The track shown in the drawing is divided by means of insulated joints 2 into a pluralit of track sections il BC, C-QD. D-E. E F. F ll, G H and HJ, etc.

'lrat'fic moving from right to left. that is. westbound trattic over the stretch of track shown in the drawing. governed by trackway signals V, l \V and W located at points H, F, (l and A, respectively. [n a similar manner eastbound trailic, that is, tra'liic moving from left to right through the stretch of track shown in the drawing. is governed by signals Tl. 1Y W". and W located at points A. C. E and H. respectively. The signals \Y may he of any suitable type and as he'rc shown are threeposition semaphore. signals. each comprisinn a semaphore blade capable of in .niing three distinctive positions at O. and ill) angular degrees with respect to the ground in which positions the signal displays a stop indication or a caution indication or Serial No. 887,960.

a proceed indication, respectively. The :-:i; ;nals are controlled in accordance with standard practic in absolute permissive block signaling, so that when a westbound train passes signal -W" the opposing signals lV'. ll, W and Vi assume the stop indication. and when an eastbound train passes signal W, signals ll, ll and N assume. the stop indication; whereas the signals governing trallic in the direction in which a train is moving operate in accordance with standard double track signaling. The means by which the signals are contr' lled in this manner terms no part of my present invention, and is therefore omitted from the drawing' for the sake of simplicity. Associated with each signal V. is a circuit controller designated b the rcl'ercncc character 1: with an exponent ctu-respiaiding to the location and arranged to occupy one position when the associated signal indicates proceed or caution and to occupy a different position when the associated signal indicates stop. Each of the signals except ll and W is Further provided with a circuit controller designated by the reference character P with an expoi cut corresponding to the location. The purpose and tunction of each device K and P will appear as the explanation proceeds.

llach track section is provided with a direct currenttrack circuit comprising a battcry 1O constantly connected with the rails adjacent one end ol such section and a direct current track relay here designated by the reference character P with a suitable exponent and constantly connected withthe rails adjacent the other end ol. the section. For example, sections ih'B, CD, i ---G and l t-fi l each comprise a battery 10 located at its right hand end and a relay It located at its lett hand end. The remaining sections lrl-(l. Ill- E and GH and the partial sections immediately to the left of point A and immediately to the right of point J are prrwidcd with batteries 10 adjacent their left hand ends and relays R adjacent their right hand ends.

JLSSOClLltQd with each signal N W and .V is a stick l'tltly designated by the reference character S with an exponent corresponding to the location. Each such stick relay is controlled by means not shown in the drawing); in such manner that when a train moving in the direction in which the signal governs, passes the associated signal, the relay is energized, provided the signal. is displaying a. proceed or a caution iudication, and the stick relay tl'u-njcafter remains in its energized condition until the entire train passes the next signal in, wt

Vance.

Each track section is also provided with two sources of alternating track circuit current, here shown as track transformers, one located at each end of each section and designated by the reference characters T with eX- ponents corresponding to the locations. The secondary 11 of each track transformer 'l which is located adjacent the tracl: relay R is connected in parallel wi h such rclay, whereas the secondary 11 0 each track transformer T which is located at the hattery end of a section is interpcsell r, etweeu such battery and one rail 'l of he corresponding section. The primry 1:3 of each track transformer T is at times supplied, as will he hereinafter explained, with alternating current from certain line transfornr ers located at intervals with the trackway and each designated by the reference character O with a suitable exponent. The pri mary of each line transformer G is constantly supplied with alternating can-rent from one phase of a quadrature two-phase alternator M over line wires 3 and 3.

The energization of each. track transformer, that is, the su iply of alter-mating current to the primary of such transforniier, is controlled in part by a si nal located in advance of the transfm'mer. For example, when signal W indicates proceed or caulion, and stick relay 8 is dc-ener led" and relay R is energized, a circuit is closr l over which current flows from secontuiry 135 of transformer 0 over wire Ll, contact l: ---'i l of circuit controller Kiwire1?,hacl;cont-act 18 of stick relay 53, wire 19, impedance 6, primary 12 of transformer T wires 230 and ill, contact 23--2-I of circuit controller wire 25, front Contact 26 of relay ll. and wire 27 hack to secondary 13 of trar. iormer O. It will he plain that when this circuit is closed alternating; track circuit Cl rrent of one relative polarity which I will term n mal relative polarity is supplied to sec A B bytransformerT .rinotl'aer 'ircui' provided which passes from secondary 1- 3 transformer 0 through wire lei; :outact of circuit controller if", wires ill and 20, primary 12 of trans former pedance 6. wire 19, front contact l8 o rel a y wire 28, contact 29-2-l of circuit controller K wire 25, front contact mi of relay it, and wire 27 back to secondary l) of transformer O. This circuit is closed oul ref sauce when signal ll is at stop and relays fl and are l'iotli energized, under wh'ch conditions alternating track circuit current ol. the oti l er rel: ,lVC polar which l will term reverse relative polarity, is suplied to section 4B by transformer 'l When signal. V1 iin'licutes CPHllOl'l or nocced and relay ii is (le -energized, a circuit 's closed over which current flows from secondary 11213 of trsmsfin'mer O, through wire 14., contact l5--16 of circuit controlcr K, wires 17 and lit. priu'uary of t T21 nsformer ll. wire 31 hack contact 26 of relay It, andv wire back to secoi'ulary 13 of trrnsnn-iucr O l v hen this circuit is closed alternating;- track circuit current of normal. relative polarity is simplied to section lll-C by transformer T.

The control of transformers T and 'll by si nal al and the control. of transformers T and T of signal W will be readily understood from the foregoing.

Referring now to signal ll, the circuit controller it. asszwiatei with this signal operates as a pole changer to supply current of normal or reverse relative polarity to truiisformer T. To accomplish this result contact u'iemhers 15 and of circuit controller lrl are connected by means of wires ill and 35 with the terminals of secondary lb of transformer G The circuit for transformer T passes from contact members 23 of circuit controller Iii, wire 22, front contact 232 of relay Ill. wire :3 impedance 6, primary of trzuisformcr 'll, wires Set, 20 and ill, hack to contact member 16 or contact member 29 of circuit controller K. It follows that when relay it is energized section l3--G is supplied. by transforn'ier 'l. with alteruatiim' track circuit current of norn'ial relative polarity when signal il is at proceed or caution and with ultcrnatir track circuit current of reverse relative olarit when signal ll is at stop. ll hen relay ll is deenero incd the supply of current to transformer T is interrupted at front contact @152 thereon and a circuit is closed, providiiu): signal ll in diculcs caution or proceed. over which current flows from contact member 223 of circuit contro ler li through wire hut-l; contact 232 of relay R, wire 36, primary if of trail former ill, wire 37. circuit controller l operated by signal ll and wires 3?; and ill hack to contact member ll; o l circuit coutroller this circuit is closed section Ii. ,3 is suppli d with aheruutiim lracl; circuit current of normal rnatiyc polarity by transformer 'l Signal. W controls trausformers T and il in the smile manner as just described in connec! ion with the control of transformers 'l" and 'l by signal l l and in addition l controls transformer T as fol- Contact 'emhers and 2% of circuit controller K are connected by means of lUU till

wires 40 and 41 with the terminals of secondary 13 of transformer O and the circuit for transforn'ier T passes from contact member 23 of circuit controller K through wire 39, -trout contact 42 of relay R wire it 'l'ront contact etG of track relay R wire 47, circuit controller P operated by signal W, wire l8, primary 12 of transttormer T and wires 20 and 49 back to contact members 16 and 29 of circuit controller K. This circuit :is closed only when relays R and R are both energized and signal V. is indieating stop, under which conditions section EF is supplied with alternating track circuit current of normal relative polarity when signal W indicates caution or proceed or with alternating track circuit current of reverse relative polarity when signal indicates stop.

The control of transformers T, T and T by signals and W will be readily understood froin the foregoing. Signals and W control certain apparatus part of which is associated with portions of track not shown in the drawing in a manner which will be apparent from the drawing and will be understood without further description.

Means are also provided for supplying to the rails in parallel of each track section a current which I will hereinafter term a local current. For this purpose I connect an impedance & across the rails adjacent the le't't hand end of each section and a similar impedance 4. across the rails adjacent the right hand end of each section. The connections for the local circuits are then made to the mid-point of these in'ipedances. The immediate supply or" local current for each track section is a local transformer desig nated by the reference character U with an appropriate exponent and having its primary winding constantly energized from one winding oi the two-phase alternator ill over line wires 3 and 3. Referring for example to section AB, the local circuit for this section passes from secondary 52 of transformer U. tl'lrough wire 53, impedance 4. in section A B, through the rails of the section to impedance l, and wire 54, back to secondary of transformer U. It is therefore clear that section A-B is constantly supplied with local current. Similar local circuits are provided for each of the remain ing sections except for section H--J and the partial section in'nnediately to the left of point A. The local circuit for section I-l-J is the same as just explained for section .\--B except that a contact 8 controlled by switch T of passing siding X is inserted in this circuit. The contact 8 is so arranged that it is closed when switch T is in such a position as to allow movements of trallic through the section HJ, but is open when switch T is in such a position as to allow movements of trafiic, into or out oi passing It follows that local current is siding X.

supplied to section H-J only when switch 4 is in such position as to permit traffic. moveuienls through this section. Contact 8 of switch 7 o'l passing siding X controls the local circuit of the section immediately to the lcil of point A in a similar manner.

Before explaining the operation of the apparatus as a whole, it should be pointed out that the lrackway apparatus here shown and described is suitable for, though by no means limited to. co-opcralion with train carried governing means in the following manner: ll'hcn the train occupies a stretch of track which is supplied with t'aclr cir cuit current of normal relative polarity and also with local current a proceed indication is received on the train. lVhen the portion of track occupied by the train is supplied with track circuit current and local current the relative polaritv of either of which ourrcnts is reversed. the train receives a caution indication and when the train is on a stretch of track to which the supply of track circuit current or local current is for any reason interrupted. a stop indication is received on board the train.

The indications are received on board the train in at least one form of train carried apparatus arranged to if'unction in this inanner through the medium of certain pick-up an 'atus located on the train in advance of the lorward axle. In apparatus of this type it is evident that the source of track circuit current must always be located in advance ot the train as otherwise the track circuit current would be shunted away from the ph i-up apparatus by the wheels and axles of a train. In my present invention it will be clear that for trallic movements in either direction through the stretch of track shown in the drawiiu the supply of track circuit current is always located at the end of the section towards which the train is proceeding.

.311 such systems. it is desirable to have the track circuit current displaced in phase with rcrpcct to the local currents. In my invention this is accomplished by supplying the local transformer with current from. one winding of generator M and, supplying the track transformer from the other phase of this generator. The lo 211 currents and track circuit currents are therefore in quadrature.

frs shown in the drawing. all oi the apparatus is in th: condition corrcswnuling to an unoccupied condition oi? the track, that is. all of the signals ll" are indicating procccd. all oi the track relays it are energized by their associated batteries 10. and all of ihe stick relays ti arc de-encrgiycd. r wilches T associated with passing silings X and K are each in such position as to permit movement of traf ic through the stretch of single track. In explaining the lUU ope ration of the apparatus, I will first assume that a westbound train. moves through the stretch oi? track shown in the drawing. its this train passes signal i i this signal moves to SLOI) position and the opposing signals ll i i ill and "i l also move to stop position. Signal ll however, indicates proceed, and as a result tr-icl; circuit l!i"- rent of normal relative polarity is supplied to section (li' l f'li by tra "lc. tiaiiishii'i'uci' T Local current. is also supplied to this tion by secomiarv oi oi transformer U a and inc train therefore receives a proceed iniilica ion as it passes l'lll'titlkll thi section. its the train enters section 11 rel 1y it heroines (lo-energised thus .interruptii i in the supply of alternating track circuit current to s tion H and completing the circuit at hack. contact 5t of relay ll il or transformer T which now supplies alternating track circuit current of imrnial relative polarity to section F t}; at the same time local current is supplied to this section through secondary 52 oil? transformer U The train therefore still receives a proceed indicatimi. The entrance of the t 'ain into section ltlcauses the encrgization oi rel a 1* and, can. e

signal. Vi to indicate sto ml l? is, however, at proceed and therefore-2 tract: circuit current oil normal relative polaritv 1s raw supplied to .i'eriion .l -l? h) transformer and local current supplied to this section by secondalfl oii transti'nrniicr U The train therefore receives a proceed indication throughout section E ir. lt will he obvious from the drawing that as the t ain proceeds successively through sections .D-li. C.D, B-C, A-B, etc, the proceed indication will continue to he received on board the train. .l will assume however that after moving}; into section lfil-l?, the train stops. Under these conditions relay ll is again cnerqined by current from battery and track circuit current of reverse relative polarity is ther fore supplied to section tl-d-ll troin trout contact 18 of stick rclav Si hut no alternatin track circuit current is su lion F(;ir since circuit: controller is reversed, signal d indicating stop. it. now,

a 'l'ollowiiu train enters the stretch of traclr shown in the drawing it will receive a caulion indication tl'irouuhou 1 section (i H and will receive a stop indication due to the interruption o't alternating; track circuit cur rent as the train proceeds through section F-G. If the train attempts to enter section E F it will continue to receive a stop indication since the alternating: track circuit currentsupplied to this tion lyv transtornier T is shunted away from the pickup apparatus of the iollovriiur t'ain hy the wheels and axles of the train already occupying section E-F. Similar protection is afforded against :lollowing trains throughout the stretch. Tht operation of the aproac es paratus when the stretch is traversed by aasthounifl iltilllfii is similar to that for westltound (rattle and will. he iuulerstomil without. turtl'ier ezqilanation.

' l will now assiu'ne that an easthouniil train cute as the stretch (it track and tips in section J -d5. t gn li il l S and ll will thenof course, display stop iudii'tations. it, under tl'iese coiulitions, a train moving 'lroin right to left at'leuipts to pass through the strctcl'i of track it will receive a stop indication ilii'Otltl'llOilil this stretch. l 'Vhen the train is in section (h ll: it will. not receive tracl: circuit currci'lt as the supply oi current to transiornier T is interrupted at :l'ront contact 18 oil stick rclajv 53" since circuit contri'iller K is now reversed, hecaus signal V1 indicates stop. its the train enters section F-tir it will continue to receive a stop indi ration since relay R then becomes (lo-energized and the supply of current to primary 12 of transformer T is then interrupted. In a similar manner the .siipply of track circuit current to each section is interrupted for moves from right to left.

If a train moving from right to left passes signal W, trains moving from halt to right and subsequently entering the stretch will receive a stop indication in a similar manner.

Although I have herein shown and described only one term of railway tratlic controlling apparatus embodying my invention it is understood that various changes and modifications may he made therein within the scope of the appended claims without departing" from the spirit and scope of my invention.

Having thus described my invention what I claim is:

1. Railway tra'tiic controlling a 'iparatinfs comprising a, stretch of railway track di vided into a tin-ward section and. a rear section, a signal controlled. by traiiic conditions in advance of said forward sectiorn a relay arranged to he eneru'ized when a train passes said signal moving); in the direction in which the signal governs, and means controlled by said relay and hv said signal for supplying track circuit current to the rails of said sections.

Railway 7 comprising; a stretch ol railway track divided into a tin-ward t-l'ltfiilOll and a rear section, a sigmal cimtrollrd. h v tratlic condi tions in advance ot said forward section, a stick relay associated with said signal. and means coi'itrolled by said stick rela and by said signal tor supplying track circuit current to raid rear section and said forward section.

l'taihvay trattic controlling apparatus comprising a stretch o't railway track divided into a forward section and a r or section, a signal. controlled by traliic conditions t *aiiic controlling apparatus "ill lll)

in advance of said forward section, a stick relay associated with said signal, means con trolled by said signal for supplying track circuit current to said forward section, and means controlled by said signal and by said stick relay for supplying track c'rcuit current to said rear section.

4. Railway traffic controlling pp-aratus comprising a stretch of railway track divided into a forward section and a rear section, a signal controlled by tratiic conditions in advance of said forward section, and means controlled by said signal and rcspoir sive to tratlic conditions in said forward sec tion for supplying track circuit current to said sections.

5. Railway tratlic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear section, means controlled by traftic conditions in advance of said forward section, a source of energy constantly connected with said forward section, a track relay also con-- stantly connected with said forward section and responsive to energy from said source, and means controlled by said relay and by said means for supplying alternating track circuit current to said sections.

6. Railway traffic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear section, a signal controlled by traffic conditions in advance of said forward section, a source of energy constantly connected with said forward section, a track relay also constantly connected with said forward section and responsive to energy from said source, means for supplying said rear section with track circuit current of one relative polarity when said signal indicates proceed or caution and of the other relative polarity when the signal indicates stop, provided said relay is energized.

7. Railway traffic controlling apparatus comprising a-stretch of railway track di vided into a forward section and a rear section, a signal controlled by trailic conditions in advance of said forward section, a source of energy constantly connected with said forward section, a track relay also constantly connected with said forward section and re sponsive to energy from said source, and means controlled by said relay for supplying said rear section with track circuit current of one relative polarity when the signal displays a more restrictive indication and of the other relative polarity when the signal displays a less restrictive indication.

8. Railway traffic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear section, means controlled by tratlic conditions in advance of said forward section, a source of energy constantly connected with said forward section, a track relay also constantly connected with said forward section and responsive to energy from said source, and means controlled by said relay for supplying said rear section with track circuit current of one relative polarity when traliic conditions in advance of said forward section are safe, and of the other relative polarity when trallic conditions in advance of said forward section are dangerous, and means controlled by said relay and by said first means for supplying track circuit current to said forward section.

9. Railway tratiic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear sec tion, a signal controlled by traffic conditions in advance of said forward section, a source of energy constantly connected with said forward section, a track relay also our stantly connected with said forward section and responsive to energy from said source, and means controlled by said relay for supplying said rear section with track circuit current of one relative polarity when the signal displays a more restrictive indication and of the other relative polarity when the signal displays a less restrictive indication, and means controlled by said relay for supplying track circuit current to said forward section when the signal displays a less restrictive indication.

10. Railway tra'ttic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear section, a signal controlled by traffic conditions in advance of said forward section, a source of energy constantly connected with said forward section, a track relay also constantly connected with said forward section and responsive to energy from said source, means for supplying said rear section with track circuit current of one relative polarity when said signal indicates proceed or caution and of the other relative polarity when the signal indicates stop provided said relay is energized, and means for supplying said forward section with track circuit current when said relay is de-energized and said signal displays a proceed or a caution indication.

11. Railway traiiic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear sec tion, a signal controlled by traffic conditions in advance of said forward section, a source of energy constantly connected with said forward section, a track relay also constantly connected with said forward Section and responsive to energy from said source, a first track transformer having its secondary constantly connected with the rails of said rear section, a second transformer having its secondary constantly connected with the rails of said forward section, a stick relay associated with said signal, a circuit includlillli ing a front contact 01f said track relay, a hack contact oi said stick relay, and a contactcontrolled by said signal for supplying the primary of said. first tra .t'or1ne1- with current of one relative polarit circuit including a :tront contact of sad. and a contact conlirollei'l by said supplying current oi the other l'GlElLlVQ lei-icy to the printiary oi said, first transformer, and a circuit tor theprimary oil said second transfornn-ajii'1 :nidii a hack contact of said track relay and a contact controlled 'ov said signal.

Railway tra'liic c rolling apparatus comprisinp a stretch oi? railway track divided into a forward section and a rea section, a signal controlloiil by traiiic (OlllllEiUIll-i in adrince of said forward, section, and means controlled by said signal for sup 1 ing track circuit current to said rear said forward sections, and means or cor.- stantly si'lpplyinn local current to sa d soclion 1"). Railway traliic controlling apparatus comprising a stretch oil rail way tracl; di- \ided into a l'or .vai.'d section and a rear section, a signal controlled by traffic ,:oinlitions in advance oi? said forwa d. smtion, and means controlled liy said si al for Slll'lplji'- track circuit current to said rear and said "forward sections; a direct curren tract: circuit for each section includin a sourcc oi? direct currei'n'i, a track relay. the rails oil? the section; means :li'oi: cons-@tnntlv on, plying each section with local. current, mean "for siu iiplying said rear sec'on circuit current oi? one reh the other according to the played by said signal, and means current or not according to the i1 display 1d by said signal.

1%. .llailwa-y trallic (Ollll'illlllljlj apparatus conjiprising a stretch of railway track divided into a forward section '1. rear all; in

section, a si' nal contr lled by trallic "0min tions in advance oil? said lorwari'l l c and means controlled by said plyii'lg; track circuit current to said forward sections, a direct current trznl: circuit for each section inclrulin a. source of direct current, a track relay, and the rails 01 the section, means tor constantly supplying: each scctioi'z with local current. means controlled by the track ClI'Clllll for said for-- ward section for supplyiu said rear lotion with alternating tracli: ci iii; current of one relative polarit or the other wool-ding; to the indication played hf; said signal, and means also controlled by said track circuit for the forward section and said, signal for supplying: said forward section with alternatine; track circuit current.

Railway tralfic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear section, a signal controlled by traflic conditions in advance of said forward s ion, a stick relay associated with said signal, means for supplying alternating track circuit current to said rear section, and means for interrupting such supply when said signal indicates stop unless said stick relay is energized.

16. Railway trattic controlling apparatus comprising a stretch of railway track divided into a forward section and a rear section, a signal CODllOlh-Bd hy traliic conditions in advance oi said forward section, a relay arranged to he energizei'l when a train passes said signal moving in the direction in which the signal governs, means i'or sup tilying said rear section with alternating current of one relative polarity or the other according to the indication displayed by the signal. and effective to interrupt such supply when said signal indicates stop unle s s-aid relay is energized.

17. Railway tratlic controlling apparatus comprising a stretch of railway divided into a first section, a second section, and a third section, a signal for governing tratlic moving in one direction away from said first sec tion, a second signal for goveii'niz tral'l'ic entering said third section in the other direction, means controlled by said first and said second signals for at times supplying alternating track circuit current to sezaid third section and governing means controlled by said current.

1 Railway traflie controlling apparatus comprising a stretch of railway divided into a first section, a second section, and a third section, a signaltor governing trailic moving in one direction away from said first section, a normally de-energized relay arranged to he energized when a train passes said signal moving in the direction in which said signal governs, a second signal for governing tral'lic entering said third section moving in the opposite direction, means controlled by both said signals and by said relay for supplying track circuit current to said third section, and governing means responsive to said current.

19. Railway trallic controlling apparatus comprising a stretch of railway divided into a. first section, a second section, and a third section, a signal for governing trafiic moving in one direction away from said first section, a normally de-energized relay ar ranged to he energized when a train passes said signal moving in the direction in which said signal governs, a second signal for governing tra'llic entering said third section lllll third section, and governing means respon sive to said current.

20. In combination, a stretch of railway track divided into a forward section and a rear section, a pole changer capable of assuming two positions and arranged to as same one position or the other in accordance with traffic conditions in advance of said forward section, a track 1 318.}: for said forward section, means including a front contact of said relay and said pole changer for supplying alternating trac; circuit current to said rear section, and n'icans including a back contact of said relay and said pole changer for supplying alternating track circuit current to said forward section.

9i. In combination, a stretch of railway track divided into a forward section and a rear section, a pole changer capable of assuming two positions and arranged to assume one position or the other in accordance with traffic conditions in advance of said forward section, a track relay for said for ward section, a stick relay arranged to be energized when a train moving away from said rear section leaves said forward section, means controlled by said stick relay and said pole changer and including a front contact of said track relay for at tin'ies sup plying said rear section with alternating track circuit current, and means controlled by said pole changer but not by said stick relay and including a back contact of said track relay for supplying said forward section with alternating track circuit current.

In combination, a stretch of railway track divided into a forward section and a rear section, a pole changer capable of assuming two positions and arranged to assume one position or the other in accordance with traflic conditions in advance of said forward section, a track relay for said forward section, a stick relay arranged to be energized when a train moving away from said rear section leaves said forward section, means controlled by said stick relay and said pole changer and including a front contact of said track relay for at times supplying said rear section with alternating track circuit, current of one relative polarity or the other, and means controlled by said pole changer but not by said stick relay and including a back contact of said track relay for supplying said forward section with alternating track circuit current.

23. In combination, a stretch of railway track divided into a forward section and a rear section, a contact mechanism comprising two fixed contact members and a movable contact member arranged normally to engage a first said fixed contact member but to engage the second said fixed contact member when a train moving away from said rear section leaves said forward section, a stick relay arranged to be energized when said train leaves said forward section, and means controlled by said contact mechanism and by said relay for supplying alternating track circuit current to said rear section.

24-. In combination, a two phase alternator having two windings in which the currents are in quadrature, a stretch of railway track, means for supplying alternating current to the rails of said stretch in series from one said winding, and means for supplying alternating current to the rails of said stretch in parallel from the remaining windin 25. In a railway traffic controlling system, comprising a stretch of railway track divided into successive sections, a track circuit for each section including the track rails in series, and a local circuit for each section including the track rails in multiple, the combination with the above-mentioned instrumcntalities of a two phase quadrature alternator having two windings and means for supplying current to all said local circuits from one said winding and to all said track circuits from the remaining said winding.

In testimony whereof I affix my signature.

RONALD A. MGCANN.

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