US1624125A - Railway-traffic-controlling apparatus - Google Patents

Description

April 12 1927.

H. A; WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS Filed July 5, 1925 2 Sheets-Sheet 1 INVENTOR V "April a 1,624,125 H. A.. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS Filed July 5, 1923 2 Sheets-Sheet 2 INVENTOR NLL/I/MM, 41- 45mm Patented Apr. 12, 1927.

UNITED STATES PATENT OFFICE.

HERBERT A. \VALLACE, OF EDGEWOOD BOROTJ'GH, PENNSYLVANIA, ASSIGNOR TO THE UNIGN SWITCH & SIGNAL COMPANY,

PORATION OF PENNSYLVANIA.

OF SWISSVALE, PENNSYLVANIA, A COR- RAILWAY-TRAFFIC-CONTROLLING APPARATUS.

Application filed July 5, 1923.

My invention relates to railway traffic coutrolling apparatus, and particularly to apparatus of the type comprising train carried governing mechanism controlled by energy received from the trackway. More particularly my invention refers to the track way portion of suca apparatus.

1 will describe two forms of apparatus embodying my invention, and Will then point out the novel features thereof in claims.

in the :urcompanying drawings, Fig. l is a diagrammatic view showing one form and arrangement of apparatus embodying my invention. 2 is a view snowing one modification of a portion of the apparatus illustrated in Fig. 1 and also embodying my invention.

Similar reference characters refer to similar parts in both of the views.

Referring first to Fig. l, the reference characters 1 and l designate the track rails of a railroad over which tra'liic normally moves in both directions.

divided, by means of insulated joints i into a plurality of successive track sections A-ll. B-C, etc. Located adjacent each end of each such section is a source of track circuit current here shown as a track transforn'ier designated by the reference character T with a distinctive exponent and the secondary 7 of which is constantly connected across the rails of the associated section. Interposed between one rail 1 and the secondary 7 of each such track transformer T is an impcdance 10. one function of which is to limit the output of the associated transformer when its terminals are short-circuited by the wheels and axles of a train. Each end of each section is also provided with a track relay, here designated by the reference character R with a suitable exponent, and comprising two windings 11 and 12. One winding 11 of each track relay is constantly supplied with alternating current from a line transformer designated by the reference character M with an exponent corresponding to the location. The primary winding of each line transformer is constantly supplied with alternating current from some suitable source such as an alternator F, over line wires 9. Referring particularly for example. to relay R a circuit is provided which passes from the secondary of line trans former M through wire It winding 11 of Th ese rails are.

Serial No. 649,442.

relay R and Wires 15, 16 and 17, back to transformer M Each section is provided with two stick relays, one located at each end of the section, and here designated by the reference characters S with suitable exponents. Each section is further provided with a repeater relay located adjacent the left hand end of the section and here designated by the reference character P with a suitable exponent. Each such repeater relay repeats the condition of the stick relay at the opposite end of the associated section, that is, the repeater relay is energized only when such stick relay is energized. j

The track transformer adjacent the left hand end of each section is normally de-energized but is at times energized in accord ance with the condition of the associated repeater relay P. Referring particularly to transformer T. a circuit is provided which passes from the secondary of transformer M through wires 1% and 18, front contact 19 of repeater relay P wire 20, primary winding 8 of track transfori'ner Tiand wires 16 and 1'? back to transformer M It will be clear that section B-C is supplied with track circuit current from transformer T only when relay P is energized. Track transformers T and T are controlled in exactly the same manner as ransformer T The transformer T located at the right hand end of section BC is normally energized but is at times tie-energized by the associated stick relay S The circuit for this transformer passes from line transformer M through wires 14: and 21, back contact 22 of stick relay S wire 23, primary Winding 8 of track transformer T and wires 15, 16 and 17 back to transformer M It will thus be clear that section BO is supplied with track circuit current from transformer T only when relay S is tie-energized. Track transformers T and T are controlled by circuits similar to those just described in connection with transformer T Winding 12 of the track relay associated with the right hand end of each section is constantly connected across the rails of the associated section. In the absence of any protective means however this relay would be subjected to excessive voltage when the adjacent track transformer is energized and an impedance 18 is therefore interposed between the winding 12 of each such relay and one rail 1 of the associated section. 'lVhen the track section is being supplied with track circuit current from the track transformer located at the remote end of the section, this protective impedance is unnecessary and undesirable and means are provided for shunting this impedance under such circumstances. For example, referring particularly to the impedance associated with relay R a shunt circuit passes from the right hand terminal of-impedance 13, through wire 24, frontcontact 2510f stick relay S and wire 26 back to the left hand terminal of impedance 13.

This lowresistance shunt around impedance 13'is thus seen to be closed only when relay S is energized.

,Each track section is provided with a line relay located adjacent the right hand end of the section and designated by thereference character H with a suitable exponent.

Referring particularly to line relay H a circuit is provided which passes from the secondary of transformer M through wires 14 and 29, winding of relayI-P, wire 30, front contact 31 of track relay R wire 32,

vfront contact 33 of track relay- R wires 34 It will thus be clear that when relay S is energized, relay H is removed from the Control of relay H If a train moving from left to right, or entering the stretch from another track occupies the stretch of track shown in the drawing, the line relays-associated with the right hand ends of the sections located to the right of the train are all de-energized. For example, if the train-occupied the section to the left of A, the consequent de-ener- 'gization of track relay R would cause l1ne relay H to be de-energized, the de-energization of relay H causes relay H to hethe end of the stretch.

comede-energized, and this in turn causes relay H to be de-energizedand on to It will be clearhowever that with only the apparatus shown in thedrawing, no means are provided for reenergizing these line relays and once de-energized they would remain in that condition. It will be understood however, that the portion of track shown in the drawing is a part only of a stretch between passing sidings and that the line relay H for the first section at the left hand. end of the stretch is not controlled by any other line relay, so that this relay closes as soon as the "train leaves the section. This permits each ren'iaining line relay H to close as the train leaves the associated section.

Each section is also provided with another line relay designated by the reference character G with an exponent corresponding to the location and this relay is located adjacent the left hand end of the associated section. .The' function and control of the relaysG are similar to the relays H except thatwhen a train-moving from right to left or entering the stretch from another track occupies the stretch shown in the drawing,

the line relays associated with the left hand end of the sections located to the} left of the train areall deenergized.

.Means are also provided for supplying to the rails of each sectiona current .whiclnI will hereinafter term a local current. 'Fon one local circuit passes from the secondary of a local transformer D ;the. primary of which is constantly supplied with-alternating current: from-line transformer =M through Wire339, front contact 40.01 line relay H, wire 41, front contact 42 of repeater.

relay P, wireAlS, front'contact la of stick relay S wire .45, impedance 6min section B'-C, through the rails .of .the section .to impedance 3, WiretG, front contacts?" of former D This circnitis closed only when relaysll Ptand S are; energized, 1under which conditions section BCqiss1.ipplied with local current of .what I shallnterm normal irelativeppolarity. W'Vhen i-relays P and S are energized and relay-H isdeenrgized, the local circuit passes-from lthc secondary .of transformer D through wire 39,.hack contact 40 of relay Hfl-wireati), im-

pedance 4: in section BC,;through the railsof the section-to impedance v6, wire l5, -f-ront contact 44: of stick relay-S wire 43, front contact 42 of repeater relayPf, Wire 41, back contact 47 of relay H", andwire 18, back to transformer D Then this circuit is closed section 13-0 is supplied with local current of what I shall term rev rse relative polarity between impedances 6 and 4-. It will be clear, therefore, that when relays P and S are energized section B+CdS supplied with local cnrrent of;nor1nal relative polarity throughout its length, orwith local current of reverse relative polarity between impedances 4 and 6 according as relay H is energized or de-energized, respectively.

In addition .tothe circuits: just described section B-C is provided with anothenlocal circuit which starts with the secondary of transformer L". the primary of which is Cir constantly supplied with alternating current ill from transformer W and passes through wire 50, front contact 51 of line relay G wires 52 and 15, impedance 6 in section BC, through the rails to impedance 3, wires 46 and 53, winding 27 of relay G wire 5%, front contact of track relay R wire 56, back contact 42 of rep-eater relay P wire 43 back contact a l, of stick relay S wire 57, front contact 58 of relay (.i", Wires 59 and 60, front contact 61 of relay Ur, and wire 62, back to transformer L Th'Is circuit is closed only when relays it and Gr are energized and relays S and P are tie-energized, under which condition section B-C is supplied with local current of normal relative polarity. In case relay R and are energized and relays 8 P and G are tie-energized, the local circuit pa, from the secondary of trai'isformer lr', through wire 50, back contact 51 ct relay G wires and 59, front contact 33 of stick relay S wire 5'7, back contact let of stick relay S wire 43, back contact 4-2 of repeater relay P wire 56, trout contact 55 of track relay R wire 5%, wind ng 21' of relay G wires 53 and 4.6, in'ipedance 3 in section B-C, through the rails of the section to impedance 5, wire 64, back contact (31 of relay G and wire 62, back to trans former L and section l3-C is then supplied with alternating current of reverse relative polarity from impedance 3 to impedance It is therefore plain that when either of the last mentioned local circuits for section l3-C is closed, relay G is energized. it, however, under such conditions, relay R is de-energized, wire 56 is connected from wire 54: by the opening of front contact and becomes connected with wire 53 through an impedance 6?, thus eliminating winding 27 of relay G from the local circuit and allowing this relay to become tie-energized. The impedance (ST is then inserted in the local circuit in place of relay winding 27, and this impedance is of such a value as will limit the local current to the proper amount for train control purposes.

Each of the remaining sections is provided with local circuits similar to those just described in connection with section B-C.

lVhile I have here shown relays H and relays G as the means for controlling both the relative polarity and the lineal extent of the local traflic controlling circuit I do not wish to limit myself to such control, since said relays may also be utilized for controlling the indications displayed by wayside signals when such signals are used.

Each stick relay S is provided with a pick-up circuit and a stick circuit. Referring particularly to relay S the pick-up circuit for this relay starts with the secondary of line transformer M and passes through wires 14 and 68, back contact 69 of line relay H, wire 70, back contact 71 of track relay R wire 72, back Contact 78 of track relay R wire 74, front contact of relay G wire 76, winding of relay S and " ires 77, 16 and 17, back to transformer M This circuit is closed only when relays R R-* and H* are tie-energized, and relay G is energized, under which conditions relay S is energized. The energization of relay S closes its stick circuit and the relay is subsequently maintained in its energized condition by current which flows from the secondary o-t transformer M through wires 14 and 78, back contact 7 9 of. track relay R wire 80, front contact 81 of relay S, wires 82 and 76, winding of relay S and wires 77, 16 and 17, back to transformer M Each repeater relay P controlled as follows: Referring particularly to relay P this relay is provided with a circuit which passes from the secondary of transformer M through wires 17 and 83, front contact 84 of relay S wire 85, back contact 31 of track relay R wire 32, back contact 33 of. track relay R, wire 86, winding of relay P and wire 14, back to transformer M It will be clear from the foregoing that if relays R and R are de-energized, relay P will be energized when, and only when, relay S" is energized.

The track relay located adjacent the left hand end of each track section normally connected with the rails of the associated section but is disconnected therefrom when the adjacent repeater relay l is energized. Referring particularly to relay R for example, a circuit is provided which passes from rail 1 of section BC, through wire 9O, back contact 91 of rep-eater relay P, wire 92, winding 12 of track relay H and wire 93 back to rail 1 of section B-U. Relays R and R are provided with circuits similar to the circuit just traced for track relay R Before describing the apparatus as a whole it should be pointed out that the trackway apparatus herein shown and described is adapted for co-operation with train carried apparatus in the following manner: When the train is on a stretch of track which is supplied with track circuit current and also with local current of normal relative polarity, the train receives an indication which I shall term a proceed indication whereby the engineman is informed that it is safe to proceed at a high speed, when the train occupies a portion of track which is supplied with track circuitcurrent and also with local current of re verse relative polarity, a different indication is received aboard the train, which indication I will term a caution indication whereby the engineman is informed that it is safe to proceed only at an intermediate speed, and when the train is on a portion of track to which the supply of either track circuit current or local current is discontinued, the train receives a third indication which I will term a slow indication and which informs the engineman that he may proceed safely only at low speed.

As shown in the drawin the apparatus is in the normal condition, that is, the portion of track shown 1SUHOCCUPlt-3Ll by trains.

Under these conditions, all the track relays R are energized. The stick relays S and repeater relays P are therefore de-ener- 'gized. and each section is supplied with track circuit cunrent from the track transformer located adjacent the right hand end of the section, whereas the track transformer located at the left hand end of each section is tie-energized. The low resistance shunts around impedances 13 are open and each section is supplied with local currentof normal relative polarity throughout its length by the local transformer L associated therewith, the relays G, G and G being included in the local circuits for the asfi-sociated sections and therefore energized.

The line relays H H and H are also energized.

I will nowassume that a train moving from left to right-enters the stretch of track shown in the drawing. The presence of the train in thesection to the left of point A. causes the de-energization of relay R which in turn tie-energizes line relay H. RelayiH -is therefore de-energized, which in turn (lo-energizes relay .l-l vI will next assume that a train enters section fir-B.

The presence of the train in this section causes relays'R and R to become deengized. The-de-e11ergizatlon of relay R removes .winding 27 of line relay G" from. the local circuit and substitutes therefor impedance 67. Relay G therefore becomes lie-energized. The closing of back contact 73 of track relay R completed the circuit for stick relay S, however, and this relay is subsequently maintained in its energized conditioniby its stick circuit as long as any part of the: train remains in section AB, although its pick-up circuit is opened at front contact 75 of relay G. as the train passes through section A B, therefore, the section is supplied withtrack circuit current from track transformer T and with local current of normal relative polarity from transformer L The train therefore receives a proceed indication. The operation of the. apparatus associated with section P-C as the train enters this section is similar to that just explained in conneci'ion with the apparatus associated with section A-B. As therear of the train passes out of section 1 15, track relays R and R? are energized by transformer T t and thus restore theappuratus to normal by including windingQ'T of relay G in the local toward the right. The apparatus associated with this section, a portion only of which is shown in the drawing, is similar to that associated with sections A 13, and 'BC, and relays R and G are therefore 'de-energized, whereas relay S is energized. Un-

der these conditions section 'BC is supplied with track circuit current from transformer T and with local current of reverse relative polarity between impedances 3 and 5 from transformer L but with no local current between impedances 5 and 6. If new a second train moving also from left to right, enters the stretch of track shown in the drawing at point A, this train'will receive a proceed indication, as before, while passing through section A"B. As this train enters section BC, however, the reversal of local current causes the train to receive a caution indication which persists till the train passes impedance 5 in'section lC. As the train traverses the remainder of the section, that is, the portion of section BC between impedances 5 and 6, it will reccivea slow indication due to the interruption of local current in this portion oi track. Track circuit current is supplied to the section to the right of point C by a transformer located at the right. hand end of this section and this current is shunted by the train occupying this section. If the second train enters this section, it will therefore be deprived of track circuit current and will receive a slow indication.

In explaining the operation of the apparatus as the stretch of track shown in the drawing is traversed by traffic moving from right to left, I will i'irst assume that the stretch of track shown in the drawing is unoccupied, and that a train n'ioving from right to left enters section l'.iC at point C. Relays R and R are imniediately de-energized. The tie-energization of relay R causes relay G to become de-energized by disconnecting this relay from its energy source at front contact relay R 'Relay G opens the circuit for relay G because relay S is open, and in a similar way each relay G to the left of the train becomes open. At the same time the pick-up circuit for relay C is closed and this relay is thereupon energized, and is subsequently maintained in its energized condition by its stick circuit although its pick-up circuit is opened by the de-energization of relay B The energization of relay S closes at its. front contact 84, the circuit for repeater relay P which is thereupon energized. The energization of relay S furthermore de-energizes transformer T and closes the shunt around impedance 13 associated At the same time repeater relay 1? disconnects relay R from the rails of section BG and energizes track transformer T The operation of relays S and P also opens the circuit for transformer L and closes the local circuit for transformer D Section 13-0 is, under these conditions, supplied with track circuit current from transformer T and with local current of normal relative polarity throughout its length from transformer D and the train receives a proceed indication. After the train has passed out of section BG, track relay R is energized by track circuit current from transformer T The opening of the back contacts of this relay causes stick relay S to become de-energized, which in turn de-energizes relay P The de-energization of stick relay S also opens the shunt around impedance 13 associated with relay R and energizes transformer T At the same time the de-energiza-tion of relay P de-energizes transformer T and connects winding 12 of relay R with the rails of section 13-0. The consequent energization of relay R completes the circuit for relay H which thereupon becomes energized and completes atfront contact 55 thereon, the local circuit including winding 27 of relay G which becomes energized, thus restoring the apparatus to normal.

I will next assume that a train moving toward the left is occupying section A-B. Relays It, R and H will be de-energized. If now a second train moving from right to left enter-s section BC, the operation of the apparatus will be precisely the same as described in detail in the preceding paragraph except that section B-G is now supplied with local current of reverse relative polarity between impedances i and 6 but with no local current between impedances 3 and at. The train passing through section BC will therefore receive a caution indication between impedances 4 and 6. At point at the interruption of the local current causes the train to receive a slow indication which persists after the train passes point B due to the track circuit current being shunted away by the wheels and axles of the train. already occupying section AB.

Referring now to Fig. 2, each section is provided with an auxiliary transformer here designated by the reference character X with an exponent corresponding to the 1ocation. Referring particularly to transformer X the primary winding 89 of this transformer is included in the local circuit for section BG in place of winding 27 of relay G The secondary winding 88 of transformer X is constantly connected with winding 27 of relay G It is therefore clear that the apparatus will function precisely as in Fig. 1. One advantage of the arrangement of apparatus shown in Fig. 2 is that with track relay R the relay G is insulated from the ground. Another advantage is that relays operating at voltages different from the voltage supplied by transformer L may be used economically as relays G and G etc.

One advantage of my invention is that the line wires used to control certain of the line relays, such as G by the traffic conditions in advance, also afford a return path for the local current at times supplied to the associated section. It will be clear that with this arrangement, two functions which would ordinarily each require a line wire are here performed by a single line wire.

Another advantage of my invention is that any failure in the normal local circuit for a section will deenergize the associated relay G and will cause a train approaching this section from the left to receive a slow indication.

Although I have herein shown and described only two forms and arrangements of railway traffic controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, I claim is:

1. In combination, a stretch of railway track, a relay, a local circuit for said stretch including the track rails of said stretch in multiple and also normally including a winding of said relay, means for at times removing said relay from said circuit, and trafiic governing means controlled by said relay.

2. In combination, a stretch of railway track, a relay, a local circuit for said stretch including the track rails of said stretch in multiple and also normally including awinding of said relay, an impedance, means for at times substituting said impedance for said winding, and traiiic controlling means controlled by such relay.

3. In combination, a stretch of railway track over which traffic moves in both directions, a local circuit for said stretch for traffic moving in one direction, and includ" ing the rails of the stretch in multiple, a

' for traflic moving in the what second local circuit opposite direction and also including the rails of the stretch in multiple, and a relay having a winding included 'n one said circuit but not in the other.

4:. In combination, a section of railway track, a track relay for said section, an auxiliary relay for said section, and a local circuit for said section controlled by said track relay and including the rails of said section in multiple and a winding of said auxiliary relay.

5. In combination, track, two track relays a section of railway for said section, an

auxiliary relay for said section, and a local circuit for said section controlled by said two track relays and including the rails of said section in multiple and a winding of said auxiliary relay.

6. In combination, a plurality of successive sections of railway track, an auxiliary relay for each section, and a local circuit for each section controlled by an adjacent auxiliary relay and including the rails of the associated section in multiple and a winding of the associated auxiliary relay.

7. In con'ibination, a plurality o't sections of railway track over which tit-attic normally moves in both directions, a local circuit for each section for governing traffic in one direction through the section, a line relay normally included in each local. circuit for controlling the local circuit for the section next in the rear, track circuits for the sections for controlling said local circuits, and means for each section controlled by a track relay for the section for removing the line relay from the local circuit for such section without interrupting the local circuit.

8. In combination, a stretch of railway track over which traffic moves in both directions, local circuits for said stretch for trafiie moving in one direction and including the rails of the stretch in multiple, local circuits for trafiicmoving in the other direction and also including the rails of the stretch in multiple, and relays havin windlngs included in the localcircuits "or one direction but not in the local circuits for the other direction.

9. In combination, a plurality of sections of railway track, a local circuit for each section for governing trafilc in one direction through the section, a line relay for each section normally included in the local circuit for the section, means responding to the presence of a train in each section for removing the associated line relay from the local circuit for the section without interrupting such circuit, a normally tie-energized auxiliary relay for each section, means for energizing each auxiliary relay when a train moving in said direction enters the section and keeping it energized until the train leaves the section, said auxiliary relay remaining tie-energized when a train moving in the other direction passes through the section: and means controlled by each line relay and the associated auxiliary relay for supplying the local circuit for the section in the rear with current of normal relative polarity when the line relay is energized, and with current of reverse relative polarity when the line relay is tie-energized and the auxiliary relay is energized, and for opening such local circuit when both relays are de-energized 10. In combination, a section of railway track, a source of energy located adjacent one end. of said section, means for supplying the rails of said section in multiple with local current of one relative polarity or the other from said source, a second source of energy located adjacent the other end of said section, a relay, and means for supplying the rails of said section in multiple and awinding of said relay with local current of one relative polarity or the other from said second source.

11. In combination, a section of railway track, a source of energy, a track relay for said section, a line relay; a local circuit in cluding said source, the rails of said section in multiple, a winding, of said line relay, and a. front contact of said track relay; and a second local circuit including" said source and the rails of said section in multiple and a back contact of said track relay but not including said winding.

12. In combination, a. right hand and a, left hand section of railway track, av line relay for each said section, and a local circuit for said left hand section including the rails of the section in n'niltiple and a winding of the line relay for the associated section and apole changer incorporated in the line relay for the said right hand section.

13. In combination with a stretch of rail way track, means for controlling tratfic moving in one direction over said stretch; and means for controlling trafiic moving in the other direction over said stretch and comprising a relay, a local circuit including the rails of the stretch in multiple and means responsive to trafficconditions in advance and a winding of said relay.

1%. In combination, a section of railway track, a track relay adjacent each end of said section, a line relay controlled by one such track relay, a second line relay controlled by the remaining track relay, a stick relay controlled in part by lay, a repeater relay controlled by said stickrelay; and a local circuit for said section including the rails of said section in parallel, a winding of said first line relay, a contact on one said track relay, a. contact on said stick relay, and a. contact on said repeater relay. 7

15. In combination, a section oi railway track, a local circuit for said section includini; the rails of the section in multiple, and a relay at times responsive to current in said circuit and at tiu'les unresponsive to such current.

16. In combination, a scetioi'i oi railway track, a local circuit for saic section including the rails of the section in multiple, a relay controlled by current in said circuit, and means -for at times modifying such control.

17. In combination, a section of railway track, a local. circuit for said section including the rails of the section in multiple, a

said second line relltl relay, and means for inserting a winding of said relay in such circuit only when saic section is unoccupied.

18. In combination, a section of railway track, a local circuit for said section including the rails of the section in multiple, a relay, and means effective only when sait sect-ion is unoccupied to render said relay responsive to current in said circuit.

19. In combination, a section of railway track, a relay, means for supplying current of one relative polarity or the other to a circuit including the rails of the section in multiple and a winding of said relay, and means I01 at times interrupting the supply of such current to said relay without interrupting the supply of current to the rails of the section.

20. In combination, a section of railway track, a relay, means for su 'iplying current of one relative polarity or the other to a circuit including the rails of the section in multiple and a winding of said relay, and means responsive to tratiic conditions for at times interrupting the supply of such current to said relay without interrupting the supply of current to the rails of the section.

21. In combination, a stretch of railway track over which traffic moves in both directions, a local circuit for said stretch for traffie moving in one direction and including the rails out the stretch in multiple, a second local circuit for traffic moving in the opposite direction and also inclueing the rails of the stretch in multiple, a relay having a winding included in one said circuit but not in the other, means for at times removing said relay from such circuit, and trailic governing means controlled by said relay.

22. In combination, a stretch of railway track over which tratfic moves in both directions, a local circuit for said stretch for traffic moving in one direction and including the rails of the stretch in multiple, a second local circuit for trafiic moving in the opposite direction and also including the rails of the stretch in multiple, a relay having a winding included in one said circuit but not in the other, an impedance, means responsive to trafiic conditions in said stretch for at times replacing said relay by said impedance, and traflic governing means controlled by said relay 23. In combination, a stretch of railway track over which traffic moves in both directions, a local circuit for said stretch for traflic moving in one direction, a second local circuit for trattic moving in the opposite direction, a relay having a winding included in one said circuit but not in the other, an impedance, means operative when said section is occupied by av train to substitute said impedance for said winding, and trafric governing means controlled by said relay.

2a. In combination, a stretch of railway track divided into sections, a local circuit for each section including the rails of the section in multiple, a line relay normally included in each such local" circuit for controlling the local circuit for the next adjacent section, train controlled means for each section for tie-energizing such relay when the section is occupied, and means for each such relay operating when the relay is deenergized to prevent opening the associated local circuit.

25. In combination, a stretch of railway track divided into sections, a local circuit for each section, a line relay normally included. in each such local circuit for controlling the local circuit for the next adjacent section, and train controlled means for ach section for removing the line relay from the associated local circuit without interrupting the circuit.

26. In combination, a. section of railway track, a local circuit for said section including a line relay, train controlled means operating when said section is occupied to re move such relay from said circuit without interrupting said circuit, and traffic governing means for an adjacent section of track controlled by said relay.

27. In combination, a section of railway track, a local circuit for said section including a line relay, an impedance, train controlled means operating when said section is occupied to substitute said impedance for said relay, and traflic governing means for an adjacent section of track controlled by said relay.

28. In combination, a section oi railway track, a local circuit for said section including a line relay, train controlled means operating when. said section is occupied to remove such relay from said circuit without interrupting said circuit, and a local circuit for an adjacent section of track controlled by said relay.

29. In combination, a section of railway track, a local circuit for said section includ ing a line relay, a track relay for said section operative when de-energized to remove such relay from said circuit without interrupting the circuit, and trafiic governing means for an adjacent section of track controlled by said relay.

30. In combination. a section of railway track, a local circuit for said section including a line relay, an impedance, a track relay for said section operative when de-energized to substitute said impedance for said relay, and traffic governing means for an adjacent section of track controlled by said relay.

31. In combination, a section of railway track, a track relay for said section, a stick relay controlled by said track relay, a repeater relay-controlled by said stick relay, a local circuit for said section controlled by said stick relay and said repeater relay and including a winding of a line relay, a second track relay for said section operative when tie-energized to remove said line relay from such circuit Without interrupting the cir cuit, and trai'iic governing means for an adjacent section controlled by said line relay.

32. In combination, a section ol railway track, a track relay for said section, a stick relay controlled by said track relay a re- )eater rela controlled 1) said stick rela 7 a local circuit for said section controlled by said stick relay and said repeater relay and lncluding a \YlIlCllHg of a line relay, a second traclrrelay for said section operative when"

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