US1608044A - Automatic interlocking apparatus - Google Patents

Description

Nov. 23 ,1926. 1,608,044

L. E. SPRAY AUTOMATIC INTERLOCKING APPARATUS Filed Feb. 21, 1924 INVENTOR; I Q; 1.?

Patented New 23, 1926 siren STATES PATENT 1 orricn LESTER E. SPRAY, O1 VJILZIINSBUR G, PENNSYLVANIA, ASSIGNOB' TO UNION SWITCH & SIGNAL COMPANY, OF SVISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

AUTOMATIC INTERLOQKING APPARATUS.

Application filed February 21, 1924. Serial in). 694,234.

My invention relates to automatic interlocking apparatus, and particularly to apparatus for automatically controlling traffic over conflicting routes. 4

I will describe one form of interlocking agparatus embodying my invention, and will then point out the novel features thereof in claims. a

The accompanying drawing is a diagram matic yiew showing one form of interlocking apparatus embodying my invention.

Referring to this drawing the reference characters a and 7) designate tivof railway tracks intersecting at a crossing A. The rails 1 and 1 of trackc are divided by means of insulated joints ,2 into track sections D-E, E-F track here similarly divided into sections HJ, JK and KL. within the limits of section EF of track a. and is within the limits of section J K of track 6. The crossing A is insulated from the rest of the tracks by insulated joints 2% and the rails of sections EF and J K are made electrically continuous past the cross' ing by jumper wires 2 in the usual manner. Adjacent the track section DE is a station Z. A passing siding 1V is connected with section D-E of traclra by means of a switch 136. v v

Each track section of each track a and Z) is provided with a track circuit comprising a track relay desi nated by the reference character R with a suitable distinguishing exponent connected across the rails adjacent one end of the section. and source of energy such as a track battery 3 connected across the rails adjacent theother end of each tracl;

section.

Eastbound over track a is controlled each capable of displaying 2. proceed or a stop indication. Associated with each sig- ,.l S is a circuit controller designated by he reference character X with an exponent corresponding to the location; Each circuit and ll-G, and the rails 1 and Pot The crossing is S located at;

y be of any suitable form and are I here shown as semaphore. signals" controller X is arranged to be closed only when the associated signal indicatesstop.

Each circuit controller X controls a signal repeating relay here d .signated by the reference character P with an appropriateexponent. For examplerelay P is energized only when signal S is at stop, the circuit for this relay passing from terminal B of a suitable source of energy not shown in the drawing, througlicircuit controller X wire 6, winding of relay P and backto terminal C, of the same source. Each of the remaining relays P is controlled by the associated signal in a manner similarto the control' of relay P by signal S Associated also with each signal is a stick relay here designated by the reference character Q with an" appropriate exponent. 'Ref erring particularly to stick relay Q the pick up circuit for this relay passes from terminal B, through back contact 7 oftrack relay R, wire 8. back contact 9 of signal repeating relay P wires,10 and 11, and winding of relay back to terminal C. This circuit is closed only when relays P and R are (lo-energized; Relay Q is also providedwith a stick circuit over wh ch cur rent flows'from terminal B, through back Contact 12 of track relay R wire 13, front contact 14. of relay Q wires 15 and 11, and winding of relay Q back to terminal C. A branch is provided for this sticl: circuit by means of which wire 13 may be connected to terminal B. through back contact 16 of relay R It follows that when relay OP is once orR? is de-energized. The control of each of the remaining stick relays Q is similar to the control of relay Q and will be plain from the drawing.

The "reference-characters T and T designate slow acting or time element relays here shown as thermo-sensitiye relays; each comprising a heating element 1', and an element 5 of thermo-sensitiv-e material insulated'e'lect'rically from the" associated li'eating element {1 but subj ected to the variations in; the, temperature of this element; Each ofthe thermo sensitive elements 5 is of some material which has th'echaracteristie of 'de cl'e ising'its electricalresistance response to increases in the temperature of th s elemen Therm-s er e relay sleet:

trolled over a circuit which may be traced from terminal B, through back contact 17 of track relay B, wire 13, back contact 19 of stick relay Q wire 20, heater 4 of thermo-sensitive relay T, and back to term1- nal C The-rmo-sensitive relay T controls an auxiliary relay U over a circuit which passes from terminal B, through back contact 17 of track relay B, wire 13, back contact 19 of stick relay Q wires 20 and 21, tl'iermo-sensitive element 5 of relay T, wire 22, winding of auxiliary relay U and back to terminal C. The parts are so proportioned that when heating element 4 of relay T is rte-energized, the resistance of thermosensitive element 5 of relay T is so great that the current then flowing through relay U is not of sutlicient magnitude to energize the latter relay. When the circuit is closed, however, for heating element 4, the resulting increase in the temperature of thermo sensitive element 5 so decreases the resistance of this element that the current then flowing through relay U energizes this re lay. Relay T is so constructed that a con siderable interval of time elapses after the circuit is closed for the heating element 4 before the resistance of thermo-sensitive element 5 is sufficiently decreased to allow relay U to become energized. It follows that if relay CF is (lo-energized and relay R be comes de-energized the circuit is immediate-- ly closed for heating element 4 of relay T but a considerable interval of time 'elapses before relay U becomes energized. exact length of this time may be regulated to suitlocal conditions. Thermo-sensitive relay T is similar to relay T and has a similar time element, The heating circuit for relay T passes from terminal B, through back contact 23 of track relay, 11*, wire 24, front contact 25 of relay U, wire 23. heat ing element- 4 of relay T and back to terminal C. Wire 24 may also be connected with terminal B over back contact 23 of relay or back contact 29 of relay B. and it follows that when relay U is energized the heating element of relay T will be supplied with current if one or more of relays R", R and R are de-energized At the expiration of the time interval required for thermo-sensitive element 5 of relay T to sutiiciently reduce its resistance, current flows from terminal B. through thermo-sensitive element 5 of relay T, wire winding of a second auxiliary relay U, and back to terminal C. It is therefore plain that when a circuit is closed for relay T an interval of time elapses before relay U' is energized.

A directional relay V is provided with one pick up circuit which passes from ter-' minal B, through front contact 30 oftrack relay B, wires 31 and 32, front contact 33 of relay R wires 34, 34 and 35, winding of relay V and. back to terminal C. A sec- The 0nd pick up circuit is provided for relay V over which current flows from terminal through back contact 36 of track relay B wires 37, 31, 38 and 39, front contact 40 of stick relay Q wires 41, 34' and 35, wind ing of relay V and back to terminal C. Current is at times supplied to relay V from a third pick up circuit which may be traced from terminal B through front contact 42 of stick relay Q wires 43, 39, 33, 31 and 44 back contact 45 of track relay R, wires 46, 34, 34 and 35, winding of relay V and back to terminal C. Still another or fourth pick up circuit is provided for relay V over which current flows from terminal B, through front contact 137 of relay U, wires 38, 31 and 32, front contact 33 of relay B wires 34, 34 and 35, winding of relay V and back to terminal C.

A fifth pick up circuit for relay V peso; from terminal B, through back contact 36 of relay R wires 37, 31 and 44, back contact 45 of relay R, wires 46 34, 4 and winding of relay V, and back to terminal 0. The sixth pick up circuit for this relay may be traced from terminal B, through front contact 30 of relay R, wires 31, 38 and 39, front contact 40 of relay Q wires 41, 34 and 35, winding of relay V, and backto terminal C. A seventh pick up circuit is closed when relays R and Q are both energized under which conditions current flows from terminal B, through front contact 42 of relay Q wires 43, 39, 38,31 and '32, front contact 33 of relay R wires 34, 34 and 35,, winding of relay V, and back to terminal Ci Relay V is also provided with a stick circuit over which current flows from terminal B, through back contact 47 of repeating re lay P wires 48 and 50, front contact 51 of relay V, wires 52 and 35, winding of relay V and back to terminal C. Wire mayalso be connected with terminal B by back contact of signal repeating relay P it follows that relay V, havingbeen once encrgized, is maintained in its energized condition as long as either relay P" or P is deenergized. The function and operation of relay V will appear as the "description proceeds.

Each of stop, but each is provided with an oper i circuit which. when closed causes the sociated signal to display a proceed ind The circuit for signal passes from t minal B, throi 'h front contact ,j relay B wire front .s; relay B wire 56, front contact relay B wire 53, back Contact relay B wire 60, front contact 61 of signal repeating relay P wire 62, front co tact 63 of signal repeating relay front contact 65 of signal repeating relay P wire 66, back contact 6. of stick relay Q], wire 68, front contact 69 of relay V, wire i of track 70, operating mechanism of signal S and back to. terminal. G. The circuit for: signal S passes from. terminal B through front contact 'Zl of. track relay R wire 72', back contact '7 3 of relay R wire 74, front contact 75 of track relay R wire 76, front contact 7'2 of relay R wire 78., front contact 79'of relay P wire 80, front contact 81 of relay P wire 82, front contact 83 of relay P wire 84, back contact 85 of relay Q wire 86, front contact 87 of relayV, wire 88,v operating mechanism of signal, S and back to terminal C. It should-be particularly pointed out that the operating circuits for th signals S and S are carried over front contacts of directional relay V. The circuit for signal S may be traced from terminal B, through front contact 89 of track relay R, wire 90, front contact 91 of track relay R wire 92-, back'contact 93 of track relay R wire 94, frontcontact 95 of track relay R wire 96, front contact 97 of relay P wire 98, front contact 99 of relay P wire 100, front contact 101' of relay P wire 102,vback contact 108 of stick relay QP, wire i operating mechanism of signal S and back to terminal C. The circuit for signal S may be traced from terminal B through back contact 105 of relay R", wire 106, front contact 107 of'relay R wire 108; front contact 109 of relay R ',.wir.es 110 and 111, front contact 112 of relay B wire 113, front contact 114 of relay R wires 115 and 116,,f-ront contact 117 of relay R", wire 118,

front contact 119 of relay P wire 120, front contact 121- ofrelay P wire 122, front con tact 123 of relay P wire 124, back contact 125 of relay Q wire 126, operating meche anisin of signal S and back to terminal O. The circuit just traced is provided with a branch which passes from wire 110, through wire 12?, back contact 128 of relay U, and

wire 129 back towire 116. It is therefore clear that when relay U is (is-energized, re: lays 1 3 and R are removedfrom the control ofsignal S As shown in the drawing ail parts of the apparatus are in the positions correspond ing to the normal or unoccupied condition of the track. Under these conditions all track relays R are energized and all signals S indicate stop. As a result all signal repeater relays P are energized. and all stick relays Qare ole-energized. Thermo-sensitive relays T and T are both tie-energized, as areauxiliary relays U and'U Directional relay V is, however energized over front contacts and 33' of track relays R and R respectively.

In explaining the operation of the apparatus I will first assume-that a northbound train moves over track 6. As the train enters section H'J, track relay 3* becomes e-energiz th s mpl ing, t a k tact 7 3 thereon; the operating'cirouit for sig ratus.

nail. S which signal thereupon displays a proceed indication. As soon as signal moves away from the stop position circuit controller X opens, thus allowing relay P to become tie-energized. This closes, at back contact 130 of relay P the pick up circuit forrelay QF. At the same time, the closing of back contact 17 of relay 1- C0211- pletes' a stick circuit for relay V. As the train enters' 'section JK, track relay R is deenergized and the circuit for signal S is then opened at frontcontact 75 ofrelay R Signal S therefore goes to the stop position and returns relay P to its ener 'iz'ed condition. Prior tothis movement of signal. S however, the closing of back contact 131 of relay B completes a stick circuit for stick relay Q and this relay is now maintained in its, energized condition over its own front contact, although its pick up circuit is open atback contact 130 of relay P3 which is now energized. hen the train moves out of section HIJ, relay R becomes energized but this does not affect the appa- As the train enters section lG-L, relay R is ole-energized but signal S does not clear because the operating circuit of this signal is open at back contact 67 of stick relay Q NVhen the train leaves section JK track relay R 'becomes energizedbut stick relay Q is not tie-energized, the stick circuit for this relay now being closed at back contact 132 of track relay R. hen the trainle'aves section K- L, the energizetion of" relay R causes the de-energization of relay Qlwhich returns the appa'ratusto its normalicondition. I The operation of the apparatus as a southbound traintraverses track 6' is similar to the operation of the apparatus when a northbound train moves over this track and will 'be readily understood from the foregoing.

1 I will next assume that an eastbound train moves over track a. As this train enters section D' E',.the de energization of re lay' R" completes the operating circuit for signal S whichzthereupon indicates proceed.

'At the same time the opening'of front contact 30 of relay R opens the circuit for relay V which then becomes (ls-energized. Upon the clearing of signal S after the train enterssectio1r DE, relay Q becomes energized: and this relay is held its energized' condition until the train leaves section" FG as will be clear from the drawing, When the train moves outof section the 'energization of relay R com: pletesztlie sigrth pick up circuit for relay V which therefore: becomes energized. As the train moves into section F.G, a circuit is closed forrelay V over front contact 40 of relayQ 'anrl back contact36of track relay B a Whent'he trainjlnoves outof section tli'cn g ationof l' lay completes the original circuit for relay V and relay Q becomes de-energized, thus returningthe apparatus to the normal condition.

The operation of the apparatus as a westbound train moves over track a will be understood without further explanation.

I will now assume that a train moving north on track Z) has entered section H-J. The, clearing of signal S de-energizes relay P as explained hereinbefore. If, now, a westbound train on track aapproaches crossing A, the de-energization of relay R as this latter train enters section E -Gr will not clear signal S since the operating circuit for this signal is open at front contact 99 of repeater relay l? which is now open. Signal S therefore remains at stop thus preventing the train on track a from proceeding past point F. As the train on track I) proceeds past signal S this signal goes to stop, thus re-energizing relay P but the circuit for signal S is now open at front contact 95 of track relay R de-energized by the entrance of the northbound train into section J-K. When the northbound train clears section JK, the energization of relay R completes the circuit for signal S and the train on track a is then allowed to proceed over the crossing. Similair protection is afforded to eastbound trains on track a when a northbound train is between points H and K and, also, trains in either direction over track a are prevented from proceeding over the crossing when a southbound train on track Z) is between points L and J.

In similar manner, if a train on track a is moving westward between points G and E or is moving eastward between points D and F, trains on track 6 are prevented from negotiating the crossing A.

It should be pointed out that if two trains one on track a and one on track Z) should approach the crossing and enter the approach sections such. as sections, L-K and FG at approximately the same time, the de-energization of relay R by the train on track a would de-energize relay V, thus preventing signal S from clearing till the train on track a had passed point E. It will thus beseen that trains on track a have superiority, that is, if a train on track Z) and a train on track a approach crossing A at approximately the same time, the train on track Z) will be held by the corresponding signal till the train on track a has cleared the crossing. If the train on track I) has however, caused relay P to be de-energized before the train on track a has entered section FG, relay V will be maintained in its energized condition by a stick circuit over back contact of relay P Signal S then will display a proceed indication and signal S will be held in the stop position.

It is clear from the drawing, that since the operating circuit for each signal is controlled by all the track relays for the corresponding track, the signal for any train approaching the crossing will be held at stop if an opposing train on the same track is approaching the crossing from the other direction.

If however, an eastbound train occupies section DE, a westbound train occupies section FG', and section EF is unoc-.

cupied, a train approaching the crossing on track 5 will be permitted to negotiate the crossing, since the simultaneous de-energization of relays P, and R by the trains occupying track a closes the fifth circuit for relay V thus permitting the operating circuit for signal S or S to be closed when the back contact of relay 3 or R is closed by a train approaching the crossing.

It is desirable to at times permit traflic moves on track 5 through the crossing A when a train occupies section DE. For example, a train might be standing at the station Z, or using the siding W without endangering trains on track Z). With my in vention, the interlocking is automatically released for moves over track b after a train has occupied section D E for a given time interval. I will assume a train to be standing at station Z or using siding W, or in some other way causing the de-energization of relay B. As soon as such relay becomes tic-energized, the closing of its back contact 17 causes the heating element Q of thermosensitive relay T to be energized. After a considerable time interval the resistance of thermo-sensitive element 5 of relay T is so reduced as to allow current to flow there through to energize relay U. The opening of back contact 128 of relay U opens the branch around the front contacts of relays R and R in the control circuit for signal S If new a train enters section H-J, the de-energization of relay R causes signal S to go to stop. At the same time a circuit is completed at baclrcontact 23 of relay R and front contact 25 of relay U for the heating element of thermo-sensitive relay T After a second considerable interval of time the resistance of thermo-sensitive element 5 of relay T is so'reduced that relay U beconie's energized. The closing of front contact 137 on this relay completes the fourth pick up circuit for relay V thus closing the circuit for signal S". The operation of the apparatus as this train proceeds through-the track I) or for a southbound train over track 7) will be readily understood without further explanation.

Since thermo-sensitive relay T requires a considerable interval of time for its operation, a train moving from left to right on track a will ordinarily enter section EF before relay U becomes energized. This time interval required for the operation of relayT and tliesiinilar time interval required for relay T prevent conflicting trains from simultaneously approaching the crossing A, but permit trains to move over track Z) in either direction when a train stands in section DE. u

Although I have herein shown and do scribed only one form of automatic interlocking apparatns 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, what I claim is:

1. In combination, a stretch of railway track, a second track intersecting said first track, means so controlled "as, to prevent trains on said second track from proceeding past said intersection when a train is occupying said stretch, and means effective at "the expiration of a time interval f llo ing the entrance of a train into said stretch to modify the control of said first means.

2. In combination, a stretch "of railway track, a second track intersecting said first track, means effective when a 'tra'inoccupies said stretch for preventing trailic movements past the crossing over said second track, and means 'efiec't'ive at the expiration "of a fixed time interval following the entrance of a train into said section for at times allowing traffic through the crossing over said second track.

over said intersection on the second track when a train occupies said stretch, and means effective atthe expiration of a time interval following the entrance ofa train into said section for allowing such movements of traliic "over said second track.

4, In combination, two interse'ctingrai'lway tracks, means for each track for preventing trains from approaching the intersection over such track when a train on the other track is on or near the intersection, and means for permitting movements over one track when a train is standing still on the otherv traclr adjacent the intersection.

'5. In combination, two intersecting railway tracks, means for eachtrackfor preventing trains from approaching the intersection over such track when a train on the other track'is on or near the intersection, and means including a;thermo-sensitive 'relay for at times permitting movement-s over one track when a train is standing "still on the other track adjacent the intersection.

-6. In Combination, two intersectingrailway tr clrs, a signal for governingtra' c approaching the intersection over one track and arranged to indicate proceed when a train approaches said -si'gn al, means for preventing said 5 nai from indicating-proceed it a train is approaching said intersection over said second track, and means for allowing said signal to indicate proceed it a train is standing still on said second track adjacent the intersection.

7. In "combination, two intersecting railway tracks, a signal for governing traffic approaching the intersection over one track and arranged to indicate proceed when a train approaches said signal, means for preventing said signa-l from indicating proceed if a train is approaching said intersection over said second track, 'andmeans including a time element relay for allo'w i said Sig mil to indicate proceed if a train is standing still on said second track adjacent the intersection. I

8. In combination, two intersecting .-rai lway tracks, "acontact arranged to be opera-ted when a train approaches the intersection over one track, trailic governing apparatus for the second track controlled by said contact,

andmea'ns set into operation when said contact is operated "and eifective at the ex-pication of a time interval to remove sai'd conated when a train approaches the intersection over one track, traffic governing apparatus for the second track controllechby said contact, and means' including atiine element relay for at times removing said. contact from the control "of said tra'fiic Igoverning means.

10. In combination, two intersecting railway tracks, a contact arranged to be operated when a train approaches tlre intersection over one t'racln trafiic governingapparatus for the second track controlled by said contact, and means incli' ding a time element relay set into operationw'hen said cont-act is operated and elfective at the expiration "of a time interval to remove said contact from the control of said tr'aific governing means.

11. In combination, two intersecting railway traclzs, a contact arranged to be operated when a train approaches the intersection over. on'e'track, trafiic governing apparatus for the second track control'l'ecl'by said cen'taet,means set into operation when said contact is operated and eiie'cjt'rve at the expiration of a time interval to remove said contact from the control of said manic .governing means, andmeans; for operating said 'trafiic means when train on said second track approaches the intersection. V v v I 12. In 'eonijb'in "ti'on, two intersectin railway tracks, cont'act arranged to be op'erated when a train approaches the intersection over one track, traffic governing apparatus for the second track controlled by said contact, means including a time element relay for at times removing said contact from the control of said trafiic governing means, and means for operating said traflic governing means when a train on said second track approaches the intersection.

13. In combination, two intersecting rail way tracks, a contact arranged to be operated when a train approaches the intersection over one track, trafiic governing apparatus for the second track controlled by said contact, means for at times removing said contact from the control of said tra'tlic governing means, and means arranged to be set into operation by a train approaching the crossing on the second track when said contact is removed from the control of the traliic governing means and etiective atthe expiration of a time interval to operate said trafiic governing means. I

14. In combination, two intersecting railway tracks, a relay arranged to be de-energized when a train approaches the intersection over one track, means set into operation when said relay is tic-energized and effective at the expiration of a time interval for again energizing said relay, and trailic governing means for the second track controlled by said relay.

15. In combination, two intersecting railway tracks, a relay arranged to be dc-energized when a train approaches the lntersection over one track, means set into operation when said relay is de-energized and eiiective at the expiration of a time interval for again energizing said relay, and means tor preventing traffic from passing over said intersection on the second track when said relay is tie-energized.

16. In combination, two intersecting railway tracks, a relay arranged to be de-energized when a train approaches the intersection over one track, means for again energizing said relay at the expiration ofa time interval, and trafiic governing means for the second track controlled by said relay.

17. In combination, two intersecting railway tracks, a relay arranged to be de-energized when a train approaches the intersection over one track, means including a time element relay for again energizing said relay at the expiration of a time interval, and traffic governing means for the second track controlled by said relay.

18. In combination, two intersecting railway tracks, arelay arranged to be de-energized when a train approaches the intersection over one track, means set into operation when a train approaches the intersection over the second track and effective at the expiration of a time interval for again energizing said relay, and traiiic governing means for the second track controlled by said relay.

19. In combination, two intersecting railway tracks, a track relay for one track arranged to be de-energized when a train approaches the intersection over such track, an auxiliary relay arranged to be energized at the expiration of a time interval following de-energization of said track relay, and trafiic governing means for the second track controlled by said auxiliary relay.

20. In combination, two intersecting railway tracks, a track relay for one track arranged to be ole-energized when a train approaches the intersection over such track, a slow acting relay controlled by said track relay, and trafiic governing means for the second track controlled by said slow acting relay.

21. In combination, two intersecting railway tracks, a track relay for one track arranged to be de-ener ized when a train approaches the intersection over such track, a slow acting relay controlled by said track relay, an auxiliary relay controlled by said slow acting relay, and traffic governing means for the second track controlled by said auxiliary relay.

22. In combination, two intersecting railway tracks, a track relay for one track arranged to be de-energized when a train approaches the intersection over such track, a slow acting relay controlled by said track relay, a second track relay for said second track arranged to be de-energized when a train approaches the intersection over such second track, an auxiliary relay controlled by said relay and by said second track relay, and trafiic governing means for said second track controlled by said auxiliary relay.

23. In combination, two intersecting railway tracks, a track relay for one track arranged to be de-energized when a train approaches the intersection over such track, a time element relay controlled by said track relay, and traiiic governing means for each said track controlled by said time element relay. 7

24. In combination, two intersecting railway tracks, a track relay for one track arranged to be de-energized when a train approaches the intersection over such track, a slow acting relay controlled by said track relay, traflie governing means for the first said track controlled by said slow acting relay, a second slow acting relay controlled by the first said slow acting relay, and traffie governing means for the second track controlled by said second slow acting relay.

25. In combination, two intersecting railway tracks, a track relay for one track arranged to be de-energized when a train approaches the intersection over such track, a thermo-sensit-ive relay controlled by said track relay, an auxiliary relay arranged to ill) be energized at the expiration of a time interval following the energization of said thermo-sensitive relay, a second track relay for said second track and arranged to be deenergized when a train approaches said crossing over such second track, traflic governing means for said first track controlled by said second track relay and by said auxiliary relay, a second thermo-sensitive relay controlled by said auxiliary relay, a second auxiliary relay controlled by said second thermosensitive relay, a directional relay controlled by said first track relay and by said second auxiliary relay, and traffic governing means for said second track controlled by said directional relay.

26. In combination, two intersecting railway tracks, a stick relay arranged to be energized when a train approaches the intersection moving in one direction along the first track, a track relay arranged to be deenergized as such train recedes from the intersection, a directional relay controlled by said sticlr relay and by said track relay, and tratlic governing means for the second track controlled by said directional relay.

2?. In combination, two intersecting railway tracks, a stick relay arranged to be energized when a train approaches the intersection moving in one direction along the first track, a track relay arranged to be de 'ized as such train recedes from the invLion, a directional relay controlled by said sticlr relay and by said track relay, traiiic governing means for the second track controlled by said directional relay, and means operated by said tratlic governing means for modifying the control of said directional relay.

28. In combination, two intersecting railway tracks, a stick relay arranged to be energized when a train approaches the interer 'ion moving in one direction along the track, a. track relay arranged to be desed as such train recedes from the inersection, an auxiliary relay controlled by said track relay; directional relay controlled by said auxiliary relay, said stick relay and said track relay; and trafic governing means for the second track controlled by saiddirectional relay.

29. In combination, two intersecting railway tracks, a stick relay arranged to be energized when a train approaches the intersection moving in one direction along the first track, a track relay arranged to be decnergized as such train recedes from the intersection, a second track relay arranged to be (ls-energized when a train moving in the opposite direction over said first track'approaches the crossing, slow acting means controlled by said second track relay, an auxiliary relay controlled by such slow acting means; a directional relay controlled by said stick relay, said first track relay and said auxiliary relay; and tratfic governing means for the second track controlled by said directional relay.

30. In combination, two intersecting railway tracks, signals for said tracks intercontrolled to prevent two trains on said two tracirs respectively from meeting at the intersection, and slow acting means set into operation when a train on one track approaches said intersection for releasing the signals for the other track after a given interval or" time.

31. In combination, two intersecting railway tracks, signals for said tracks intercontrolled to prevent two trains on said two tracks respectively from meeting at the intersection, an electrically isolated section in one of said tracks on one side of said intersection, and slow acting means set into op eration when a train approaching said intersection enters said section for releasing the signals for the other track it such train remains in said section for more than a given interval of time.

32. In combination, two intersecting railway tracks, signals for saic tracks intercontrolled to prevent two trains on said two tracks respectively from meeting at the intersection, and slow acting means set into operation when a train approaching Said intersection on one track ente s a given portionoi such track for releasing the signals for the other track it the train consumes more than a given amount of time in passing through said portion of track.

In testimony whereof I aiiix my signature.

LESTER E. SPRAY.

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