US2186201A - Track signal control system - Google Patents

Description

Jan. 9, 1940; s. E. M FARLAND 6,

TRACK SIGNAL CONTROL SYSTEM 2 Sheets-Sheet 1 Filed April 22, l

I I I I I L I .I

1 Jan. 9, 1940. s.' E. MCFARLA ND 2,186,201

7 TRACK S IGNAL CONTROL SYSTEM Filed April 22, "1938 I 2 Sheets-Sheet 2 Patented Jan. 9, 1940 TRACK SIGNAL CONTROL SYSTEM Samuel 'E. McFarland, Los Angeles, Calif. Application April 22, isssgserial No. 203,538

7 Claims. .(CL'2464-130) This invention relates to Signal systems and relates more particularly to an improved railway track signal system. A general objectzof this invention is to provide a simplified, inexpensive and dependable track signal control system.

This application is a continuation-in-part of my application for Letters Patent Serial No. 118,802, filed January 2,- 1937.

The block signal systems and other railway track systems now in general use are costly to install and are not altogether satisfactory. It is the general practice in such signal systems to,

employ the track rails as conductors in the circuits of the control relays which govern the signal apparatus. In most track signal systems current of voltages in the order of from 6 to 16 volts is supplied to the rails- The use of current of such voltages in signal systems has numerous dis-' advantages. For example, a signal control system employing high voltage current is always subject to disruption and failure due to current leaks and shorts when the track is Wet or submerged and it is usually necessary to insulate theblock sections or guarded sections of the track from the adjacent portions of the'track. ,In the case of electrically operated railways where the rails form the return conductor for the power current the insulation of the blocks or guarded sections of the track necessitates the employment .of impedance bonds or like devices to transmit the power current or propulsion current from one track section to another while preventing the flow of the signal system current from one track section to another. The insulated rail sections, the .impedance bonds and the other devices used in track signal systems employing current of more than' one volt are expensive and require costly inspections and repairs. Where signal control current of more than one volt is used the blocks or guarded track sections must of necessity be quite limited in length. It has been proposed to employ current of high frequency in signal control circuits where the rails are utilized as conductors and to use current of different frequencies in the adjacent blocks or track sections. The use of high frequency current necessitates the installation and maintenance of special generators and other special equipment and systems employing polyphase and high frequency current have not proven successful.

Another object of this invention is to provide a track signal control system in which the rails may be conductively continuous so that insulated rail bonds are not required and in the case of an electric railway impedance bonds or like devices are not required.

Another object of this invention is to provide a track signal control'system that is dependable under all conditions and that is unaffected by the submerging of the rails, variation in the character, of the road bed, foreign matter on the tracks, etc.

Another object of this invention is to provide a track signal control system in which the guarded portions of the track or the blocks may be of great length, for example, they may each have a length of 7000 feet or more.

An important object of this invention 1s to provide a track signal control system of the character mentioned that utilizes a track current or control current of low voltage thereby avoiding the numerous difficulties and limitations inherent in signal control systems employing high voltage current. I

.Another object of this invention is to'provide a track signal control system of the character mentioned in which the circuits of two adjacent signal controls overlap one another longitudinally of thetrackso that the desired sequence and duration of signals is assured. This feature of the invention makes the system particularly advantageous for the control of warning signals at highway intersections, etc. andprovides'for the, sustained actuation of the signals until the rear of the train has passed the intersection irrespective of the direction'of travel of the train.

Another object of this invention is to provide a track signal control. system in which two or more signal relays may be governed to operate in any desired sequence or relation by the current supplied to a single or given zone or portion of the track without cutting the rails. This feature of the invention makes it possible to control both block signals and intersection signal devices by a single power supply connected with or delivering current to the rails of a portion of the track.

Another object of this invention is to provide asignal control system of the character mentionedembodying novel and particularly efiective interlocking relays. I

A further object of this invention is to provide a track signal control system of the character mentioned that does not necessitate the employment of expensive generators or other special equipment. I

The various objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and application of my invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. l is a diagrammatic wiring diagram of the signal control system of the invention as employed in connection with a track for the control of block signals and intersection signals. Fig. 2 is an enlarged fragmentary wiring diagram illustrating two sets or pairs of control relays. Fig. 3

is an enlarged fragmentary vertical sectional view of one of the interlocking relays illustrating the improved locking means and control means provided by the invention. Fig. 4 is a fragmentary vertical detailed sectional View taken as indicated by line 44 on Fig. 3, and Fig. 5 is an enlarged diagrammatic view of one of the step up transformers and its filter.

The signal control system of the present invention is suitable for governing signals, control devices, and signal devices of various natures and. is susceptible of substantial variation to adapt it for employment in different situations. In the following detailed description I will describe the in vention as employed to operate or control the block signals and intersection signal devices associated with a portion ofa two-way track. It is to be understood that the invention is not to be construed as limited or restricted to the specific form or application of the invention about to be described.

In Fig. 1 of the drawings the numeral I desi nates the rails of the railway track. The rails I0 I may be considered as typical steel railway rails of a standard design and weight. For example, it may be considered that the rails ID are typical 75 pound rails. It is a feature of the invention that the rails I0 are conductively continuous; that is, each rail Ill forms a continuous unbroken electrical conductor. Accordingly, insulated joints are only required at crossings, sidings and at the end of a double track merging into a single track. The two rails Ii] constituting the track are electrically separate and independent throughout the length of the portion of the track protected or guarded by the signal system. The fact that the rails Iii are conductively continuous as just described is important as it materially simplifies the installation and maintenance of the track and materially increases the efliciency of the railway if electrical propulsion is used as it is unnecessary to divert or otherwise direct the propulsion current handled by the rails. I have shown a highway or road R intersecting the track and have illustrated suitable warning signals S at each side of the road R where it intersects the track. I have also illustrated a series of block signals B B B and B arranged longitudinally of the rails I0 to define blocks or guarded zones of the track. The signals S and the block signals B B B and B may be of any desired type that may be operated or governed by electrical means. The present invention is not concerned with the forms of signal devices or signals S and B 13 B and B employed and the details of these devices are omitted from the present description. The term block as used in the description of the present invention refers to a part or portion of track comprising the conductively continuous rails ID.

The improved signal control system of the present invention may be said to comprise, generally, operating circuits l2, for the block signals B B 13 and B relays I3 controlling'the circuits I2, control circuits I4 for the relays. I3 comprising transformers I5 supplying-low voltage current to the rails Ill at points between the ends of the locks or track portions guarded by the sets of signals B and B B and B and transformers le I5 I6 and Ki receiving the current from the rails I6 adjacent the ends of the said blocks and delivering the control current to the related relays IS; an operating circuit I! for the intersection signals S, relays l8 controlling the circuit 5?; and control circuits for the relays I8 comprising the power means I5, the rails I0 and one or moretransiormers I9 connected with the rails I9 and delivering the control current to the relays I8.

The operating circuits I2 for the block signals B B B and B may be connected with any suitable or convenient source of electrical energy.

In the drawings I have shown a power line 20 paralleling the track and supplying current to the circuit l2. It may be assumed that the power line 29 carries A. C. current of 110 volts. Each circuit I2 comprises a lead 2| extending from the powerline 2% to a relay I3 and a lead 22 extending from a relay I3 to the related or controlled block'signal B B B and B The signals B and B and B and B controlling or guarding the adjacent track portions or blocks may be interconnected to be simultaneously controlled or operated. A connecting lead 23 connects the lead 22 of the signal B with the lead 22 of the signal 13 and a similar lead 23 connects the lead 22 cf the signal B withthe lead 22 of the signal 3*. For the purpose of simplifying the illustration I have shown the signals B B B and B grounded and have shown the circuits l2 in broken lines to distinguish them from the other circuits of the system.

The relays I3 are provided to govern the operating circuits I2 of the block signals B B B and B and there is a relay I3 provided to control each block signal. The relays I 3 may be of any selected type, it being preferred to employ a conventional or standard line or track relay. As diagrammatically illustrated in Fig. 2 of the drawings each relay I3 includes a movable element 24 governed by two windings 25 and 26. The manner of energizing and controlling the windings 25 and 26 of the relays I 3 will be hereinafter described. The elements 24 are cooperable with sets or pairs of contacts 2'! to govern the circuits relay l3 are energized the element 24 is out of engagement with the contacts 21 and the circuits I2 are broken; While I have shown only two contacts 2'! in each relay I3 to provide for the energization of the respective signals B B B and B when the relay elements 24 drop, it is to I be understood that the relays I3 may include other contacts, for example, they may include pairs of contacts X that are normally made to provide appropriate signals at the block signals.

The control circuits I6 for the relays I3 are important features of the invention. The control circuits It assure the dependable operation of the system under all conditions of operation and are such that the guarded track portions or blocks may be of great length. The circuits I4 are supplied with current by the above-mentioned transformers I5. There is a transformer I5 for supplying current to each set or pair of circuits I4 guarding a track portion or block. The prixiii) mary windings of the transformers I5 may be portion. Conductors or leads 29 from the said secondaries128 deliver current to the windings 25. Thus the windings 25 of the relays KI3 are continuously supplied with current. 1

Each circuit I4 includes one of the secondaries 28 of a transformer I5 and leads 30 extending from thesecondary 28 to the rails II] to deliver.

the current to the rails. The turns ratio of the transformer I5 is such that'the leads 30 deliver low voltage and high amperage current to the rails I6. This is an important feature and will be hereinafter discussed. The points of connection of the leads 36 with the rails I6,'that is, the points of current feed to the rails III are also of importance. The leads 36 are connected with the rails ID at points between the ends of the guarded railportions or blocks and the two pairs of leads 36 supplying current to the two transformers I6? and I6? or I6 and I6 of a block are in spaced relation. As illustrated in the drawings the points of input or feed to the rails I fl may be spaced atopposite sides of the medial point or plane of a block, it being understood that this location of the points of feed is not essential. An adjustable resistance 3I is provided-in one lead 39 of each pair of leads 30 so that the voltage of the current supplied to the rails Il) may be regulated at will. The relationship between the character of the current, the points of feed of the current to the rails I0, the points of comiection of the related transformers I6, I6 I6 andI6 with the rails ID are factors that will be more fully described. v 3 The transformers I6 I6 I6 and I6 are associated with the rails ID to receive the track current or electrical energy therefrom. -The transformers I6 I6 I6 and 'IIS are spaced'longitudinally along the track from their respective power inputs or feeds as provided by the secondaries 28 and the leads 30 of their circuits. The primaries of the transformers I6, I6", I6 and I6 are connected across the rails II) by taps or leads 32. 1 It is to be observed that the portions of the rails is between the current feeds orv leads'3Il and the taps 32'of the transformers I6 I6 I 6 and I6 constitute conductors 'in the circuits I4.

The lengths of the portions of the rails Ill between the input leads 36 and the tranformer taps 32 are known, determined or measured. The rails it are of standard weight and of standard design and therefore have a known or fixed resistance per lineal unit. Accordingly, the portions of the rails I6 connected in the circuits I4 between the power input leads 30 and'the related taps 32 may be considered as resistances in the circuits I 4 which resistances have a given ohmage. The electrical energy delivered to a portion of the track by the leads 30 for conductance to a transformer I6, I6, I6 and l6 is of such character that it has only sufficient voltage to overcome the resistance offered by the rail portion and the adjacent bond 36 or 36 with a very small residual voltage to be stepped-up by the said transformer I6 I6 I6 or I6 In practice the electrical energy or power delivered to a transformer I6, I6 I6 or I6 through the medium of a length of the track is of such lowstrength that it cannot be read on an ordinary milliammeter or milli- 1.75 and 2 amperes.

voltmeter although the meter hasall of its readings or calibrations below 1. The bonds 36 and 36 mentioned above will be hereinafter described. I The transformers I6, I6 It or It are designed to receive the low voltage current of the character just mentioned and to step it up to sufficient voltage for the control or maintenance of the control relays I3. The transformers I6 I6 I6 and I6 are of a special type to receive very low voltage and high amperage power and step up the same to suflicient voltage to maintain therelated relays I3 in their normal condition.'

I prefer to construct both the primary and the secondary windings of the transformers Ili I6 I6 and 16 of large diametered copper wire and to provide. the primary and secondary windings with very small'cores. There is very low inductiveness in the cores of the primary and secondary windings of .the transformers IB I6 I6 or I6 so that the high potential propulsion current that may be carried by the rails It has little or no effect on the A. C. signal control circuits I4. In a typical installation where the length of a portion of track between the input leads 30 and the related transformer taps 32 of a circuit I4 is 2000 feet, the leads 36 may carry current of between and 6 amperes and the transformer I6 I6 II-5v or I61 is designed to step-up the residual voltage of between .058 and .068 of one volt, remaining after the voltage drop brought about by the resistance offered by the rails I I), to about .40 of a volt with a current strength of between From this it is to be observed that the current transformation as distinguished from the pressure transformation is the factor with which the apparatus is primarily concerned.

Leads 33 extend from the secondary windings of the transformers I6, I6 I6 and I6 to the coils or windings 26 of the related relays I3. Suitable condensers 34 are interposed in the leads 29' to bring the track current in the windings 25 in proper relation to the current in the windings 26. It is preferred to connect a rectifier or filter 35 in shunt relation across the taps 32 of each transformer I6 I6 I6 and It to filter out all electrical impulses and direct current from the rails II] that might interfere with the operation of therelay circuits I4 and the associated parts. A rectifier or filter 35 is illustrated diagrammaticallyin Fig. 5 of the drawings.

In accordance with the invention bonds 36 of low resistance are connected across the rails I0 atthe outer ends of the portion of track having the series of guarded track portions or blocks. The bonds 36 may have a resistance of between .00017 and .00022 of an ohm. The bonds 36 are spaced outwardly or longitudinally from the-adjacent transformer taps 32. The spacing of the bonds 36 from the adjacent transformer taps 32 is such that the bonds transmit little or no signal control current. In a typical installation the effective current of a circuit I4 in the rails It may bered transformer of the adjacent circuit I4 and a bond 35 is connected'across the rails in atia point spaced between the taps 32 of the adjacent. spaced transformers lfi and It. .In accordance with the invention the bonds 36 have a resistance greater than the resistance of a typical truck of a car or train. In practice the bonds 3S each have a resistance of about .003 of an ohm. The taps 32 of each transformer Ili 16 and 5 are connected to the rails II] in diagonal relation and the bonds 36 are diagonal with respect to the rails l9 and are substantially parallel with lines drawn between the points of con.- nection of the adjacent .taps 32 with the rails.

The bonds 35 carry or transmit a certain amount of the current handled by the circuits l4 and sufficient current is supplied to the rails 10 by the transformers 15 to compensate for the current handled or taken by the bonds 36. In other words, the factors of the resistance of the rails ill, the resistance of the primary windings of the transformers it, H6 and "5, the resistance of the bonds 36 and the current supplied by the transformers l5 are so related or balanced that sufiicient current is normally delivered to the relays 1-3 to maintain them energized. The diagonal arrangement of'the taps 32 and the bonds 36 provides for the simultaneous or concurrent de-energization of the relays 13 of two adjacent circuits I4 when a train truck passes over a bond 35 Owing to the fact that a train truck has less resistance than the bonds 3& the passage of a truck over a bond 36 continues to shunt out the circuit it that it is leaving until it reaches or passes the center of the bond 36, at which time the truck shunts out the circuit M that it is entering and thus the passage of the truck over the bond 36 causes concurrent actuation of the block signals of the adjacent blocks to provide the desired sequence of signal opera tion without interruption.

The operation of the apparatus thus far described will now be set forth. It will be assumed that the transformer taps 32 are located substantially 1600 feet from their related feeds or input leads 30, that the input leads 3b of adjacent circuits I4 are approximately 300 feet apart, that the resistance of the rails i0 is .000014 ohms per foot, and that the transformers i5 I8 |6 and 10 pick up current of approximately .0068 volts, and approximately 2 amperes from the rails It. It is to be understood that the efiective length of a circuit M on the track beyond the leads 30, and in the case of an end circuit l4 beyond the transformer taps 32, may be adjusted or varied by means of the adjustable resistance 3! of the circuit. It is important to note that the circuits l4 overlap on the track between their adjacent feed or input leads that is, the effective lengths of the circuits M on the rails l0 lap one over the other between their adjacent leads 30.

Let it be assumed that the relays I3 are energized and that a car or train is moving along the track from the right to the left in Fig. 1. When the foremost truck of the train passes the center of the right hand bond 36 about ten feet, the truck shunts out the transformer l6 and therefore effects de-energizatio'n of the relay l3 connected with that transformer. De-energization of the relay 13 results in energization of the signals B and 1-3 at the ends of the track block. As the train proceeds along the track the circuit Hi handled by the transformer W remains shunted out until the rear truck of the train is a considerable distance past or beyond the input leads 30 of that circuit I4. In a typicalinstallation of the'character mentioned above the rear truck of the train will reach a point substantially 285 feet beyond the input leads 3% before suflicient current builds up in the rails I0 behind the truck to energize the relay [3 through themedium of the transformer [5 It is to be understood that the distance traveled by the rear truckspast the points of current feed to the rails before the relay [3 is re-energized may be varied to suit the conditions of operation and installation by adjusting the related resistance 3!. It is estimated that when the rear truck has reached a position 285 feet beyond the input or feed leads 36, that there is .00850 of an ohm resistance in the rails l0 between the truck and the point of feed and this resistance, together with the'resistance of the truck is such that the truck is no longer effective as a shunt. Accordingly, the relay l3 supplied with current through the medium of the transformer l6 is re-ener- 2 gized when the train reaches. a point approximately 285 feet beyond the input feeds 39 of the circuit [4.

Prior to the re-energization of the relay l3 through the medium of the transformer Hi the train will have caused de-energization of the re-- lay i3 receiving its current from the transformer 16 In other words, when the rear truck of the train has reached a position 285 feet beyond the input leads 3!] supplying current to the trans- .Li

former it it is within approximately 15 feet of the input leads 3Q supplying current to the transformer lt and, therefore, is within the effective length of the circuit d4 of the transformer it Thus it will be seen that the transformer lfi will have shunted out sometime before re-energization of the relay. l3 supplied with current through the medium of the transformer H De-energization or shunting out of the transformer l's results in de-energization of its related relay l3 andenergization of the block signals B and B In the case where the block signals B and B are interconnected, as above described, the de-energization of the relay l3 supplied with current through the medium of the transformer lt may result in appropriate signal changes in the signals B and B The transformer ifi is energized to restore the related relay l3 when the rear truck of the train is some distance past its taps 32. This results from the above described relationship between impedances in the rails Iil, the bond 36 and theprimary winding of the transformer Hi the impedance of said winding being so low that the rail current of the circuit l4, taking the course of least resistance or impedance, flows in the said winding to a sufficient extent to restore the related relay l3 when the train truck reaches a position Where the impedance in the rail circuit to the left of the taps 32 of the transformer 58 is greater than that of the said winding of the transformer. In practice the transformer lfi remains shunted out until the rear truck reaches a position about 10 feetpast the center of the diagonal bond 36 Where the bonds 3% are diagonal as illustrated, the train or its trucks may cause concurrent shunting of the transformers 56 and it with the accompanying concurrentde-energization of their respective relays 13. Thus the block signals B and B E and B of two contiguous blocks are simultaneously energized during the passage of the train from one block to the otherand a continuously operating signal system is provided. Upon the passage of the rear trucks of the train beyond the bond 36 between the transformers [6 and 16 the current from the rails Ill passes through the transformer H and its voltage is stepped-up thereby to reenergize the associated relay [3. This de-energizes the block signals B and B The operation of the other circuits l4v and their related relays l3 is the sameas described above.

It isto be particularly noted that the current employed in the track circuits or control circuits [4 has just sufficient voltage to overcome 'the resistance or ohmage of the rails l0 and the resistance of and loss across the bonds 36 with a very small residual voltage that is taken and stepped-up by the transformers 16 16*, H3 and lfi' to normally maintain their related relays l3 energized. This. low voltage current does not under any circumstances leak from the rails l0, short between the rails H], or travel on down the track beyond the blocks of the respectivecin cuits l4. In actual practice it has been found that submersion ,of the track, changes in the character of the 'roadbed, atmospheric changes, changes in temperature, and the like, have no efiect whatsoever uponthe low voltagecurr'ent employed inthe system of the invention. The

overlapping of the control circuits l4 in the rails H3 between the spaced adjacent feed or'input leads 3B and the vdiagonal bonds 36 provide for v the deenergization of one relay l3 prior tothe re-energization of an' adjacent relay; It so that the track is continuously under the control of the block signal system. The longitudinal extent or effective range of a circuit M in the rails in may be readily varied by means of the adv justable resistances-3t and in practice the system' may be adjusted to provide for signal operation by theshunting effect" of a train truck at any given point onthe track with an accuracy of within a very few feet. 7

'I'he'operating' circuit 1! vfor the trafiic signals or intersection signals S may include a lead 40 extending from one conductor of the power line 20 to the signals In thedrawings I have shown the signals S grcunded, it being understood that a return conductor may extend from the signals S to the other conductor of the power line 20. The conductor 40 extends to the two the track rails 10,- or may be connected in the control relays l8 and is governed or controlled by the relays 8, -as will be subsequently described.

The relays 18 are normally energized and are' under the control of the circuits l4 of the adjacent block signals. The relays similar to the relays l3 and each comprises .a movable element 4| and two windings 42 and 43 normally energized to hold the element 4! in the up or normal position. Conductors or leads 44 may extend from the: power supply leads 29 of the adjacent'relays l3 to the coils 42 so that the coils 42 are energized at all times. The coils 43 of the relays I8 maybe connected with associated transformers l9, receivingcurrent from leads 33 from the adjacent or related transformers l6? and Hi In the particular arrangement shown in the drawings the coil 43 of one relay I8 is connected with the transformer I9 by leads 45 and the winding 43-of the other relay I8 is connected with the leads 33 extending from the transfermers Hi Suitable condensers 46 may be-provided in the leads supplying the windings 42 so that the windings 42 are properly related to the windings 43.- Each relay. [8 further includes two contacts 41 connected in the lead 49 of the signals S. Upon de-energization of a relay IB its element 4l falls' to cooperate with a' pair of: contacts- 41 'toflclose the circuit to the members !8 may be signals 6, A v

ln accord ance withth'e invention the relays l8 are interlocking relayssofthat the signals S are ole-energized following the passage of the train over the intersection or road R, that is, following themovement of .thetrainfrom one circuit 14 to the other circuit I l, .As best illustrated in Figfl'3 ofthe drawings the element of a relay I8 is v operatively connected with a segment-like mem: ber 53 pivotedIor turnablysupported at 48. "The 5B operate through the medium of suitable linkages 49 to move the contactors'or Iele-f ments 42 against the contacts 41 and the other.

contacts "of .the relays H3. The improved interconnecting] means or theinvention includes a pinii oneach member 50 and a pivoted latch 52 for cooperating with eachpin ,5}. Pivot'pins 53 sup-portthe'latches 52 at. their lower ends and posts54 ar'e adapted "to limit the pivotal movemlentoffth latches in one, direction and to normally support. the latches in reclining positions.

1 VFIhen the, latches 52' 1 rest against their posts 7 54 they: are but ofthepaths 0f, the pins 5!. 'The V upper portionsjor the latches 52 have notches 55 I for cooperating with or receiving the pins, 5|.

The interlocking means further includes: sole-,

noid coils 55 foractuating or'shifting the latches 52. The coils56 operate whenenergized to move their ,-respective latches-52 to positions'iwhere their notches 55 receive the pins 5,! so'that the latches; prevent falling or downward movement of the mn'ibersifl and their elements 4L The circuit otone coil 56 .eom risesa conductoror lead '51, connected wan suitable power =lead v suchas a lead 44 and a lead 58 extendingvto the othe r relay I8. I The lead 58hastwo spaced contacts 59 in the said other relay, It to be contacted v or fclosedby its element. The other coil .56'

has a lead 60 connectedlto a power leadsuch as one-of ith'e' leads Z9 and has its second lead 61% extending tofthj other relay l8. The leadYBl isprovided, with 'spacedwontacts 62 controlled or .engage d bythe-element4i of the said other relay Q; It will be seen thatthe de-energi'zation of one relay l 8 results:in,energization. of the coil 56 .of the other. relay It-to move the related latch'52 we position to stop the falling or to prevent thelatch .52' to an inactive position. In practice I the rej-energ-ization of a relay: [8 is accompanied by I slight, upward movement of; its member 50 r and element Al and-during this upward move- I ment the pinfil cooperateswith the notch 55 of the adjacent'latch #52 to return-the latchto its released position. l

The relay I8 current from thetrack circuit leads 33 is operablesimultaneously with the'associated relay l3. ,Thus'in the case illustrated in the drawings the shuntingout of the transformer It by a'train .truck causes simultaneous de-energization of I the the block signals; B ;-and B and; the signals; S

whose-wi ding 43 is supplied with relatedr'eIay Hiand the related relay l8 so that are simultaneously energized. Accordingly, the circuit I4 embodying the transformer It governs both a set of block signals and. thetraflic signals S and the current carried by the rails 10 is the controlling or energizingmediun'r'ofthis circuit. I

The transformer I9 receives low voltage and high amperage current from the rails I0 and delivers current of substantial voltage to its related relay I8 to normally'hold the same energized. The transformer I9 is preferably similar in construction and operationto the transformers Hi IB I Ii and.l6 described above. The transformer I9 has its. primary connected across the rails ID by taps 65and has itssecondary connected in the .above. mentioned leads 45. The taps 65 are connected across the rails I0 ata point between the taps 32 of'thetransformer I6 and the input leads 30 of the adjacent transformer I5. In this connection it .will be observed that the transformer Ifi and the transformer I9 are both supplied with current from a single set of input leads 30. A filter or'rectifier 66 similar in character to the rectifiers35 is connected between or across the taps 65 to prevent the transmission of foreign current to the transformer I9. y

The relationship between the transformers "i and I9 and the resistance in the track. rails I0 is such that the transiormersreceive current of substantially the same voltage and" amperage. The resistance across the'rails Ill offeredby'the transformer I9fis greater 'than'that oifered'by the transformer IB and the transformers, I6 and I9 are balanced with theresistance of the rails It so that thetwo transformers receive "sub? stantially thesameyoltage. 'Itwill beseen that the currentor energy, delivered'totthe. rails II] by the transformer I5; the resistance of Itheportion of track between the input leads 39 and the taps 65, and the resistance of the rails Ill between the taps 6'5 and the taps'32 of the transformer Hi must be determined and, related to provide for the above-mentioned balanced condition of the transformers I6 and I9. It is to be understood that the tapsti of the transformer I9 may be connected with the track at any desired point between the transformer taps '32 andthe input leads 30. The variable resistance 3| of'the circuit I4 may be set'or adjusted "to provide for the transmission of energy of the desired voltage and amperage tothe transformers "Hi and :I9.

The operation of the circuits for controlling the intersection signalsS' is'as follows. It will be assumed that a trainis movingalong the "track and is passing over thebond 36' between the adjacent transformers W and I6. The foremost truck of the train shunts out the transformer it when it reaches a, certain-pointspaced fromthe transformer taps 32,. said point being'about 10 feet past thecenterof-the diagonal bond 35*. When the transformer I6 is shunted out: its relay I3 is de energized and therelay I8 whose winding 43 receives current from the'transformer I6 is likewise-de-energized. De-energization of the relay I3 results in-actuation of the block signals B and B and de-energization" of the associated relay It results in actuation of the signals S. De-energization of the said relay I8 also causes closing of the contacts 62 so that the coil 56 of the other relay I8 is energized. The energized coil 56 moves the-adjacent latch 52 to a position where its notch 55 isadapted to receive the pin 5'I on the relaymember-SII. When the forward portion of the trainreaches and passes the intersection of the road R with the track the train trucks shunt out the transformers I9 and li The current of the two circuits I4 overlaps on the rails II) at the intersection of the road R and the track so that the transformer I6 remains shunted out some time after the transformers IE and I9 have been shunted out as above described. With the typical data given above, the transformer I6 remains de-energized or shunted out until' 'the rear truck of the train reaches a position about 15 feet from the taps 39 of the transformer I5 supplying current. to the transformers I6 and I9.

Shunting out of the transformers I6 and I9 results in de-energization of the associated relays I 3 and I8. De-energization of this relay 53 keeps the block signals B and B energized and de-energization of the relay I8 is accompanied by fall ing of its member 59 and element 4!. However, due to the fact that the latch 52 of the said relay I8 is held in its active position by the adjacent coil 55 the member 51'. falls only a short distance until its pin 5I is received in the notch 55. The

cooperation of the pin 5| with the notch 5t limits the down travel of the element M and stops the element before the contacts of the relaylii are closed. It is to be observed that the relay I8 governed by current from the transformer I9 is deenergized prior to the re-energization of the other relay I8 and that its latch 52 is held in the active position until the member 59 has dropped, as'just described. The latch 52 cooperating with the pin El holds the element 4| inthe inactive position and thus prevents a second or a continued energization of the signals S at the intersection or rod R following the movement of the train beyond the intersection. When the train reaches aposition where its rearmost truck is some'distance beyond the taps 65' of thetransformer I9 sufiicient current reaches the transformer I9 to effect the re-energization of its relay I8. Re-energization of this relay I8'is accompanied by a slight upward movement of its member 59 and the pin tion past or beyond the taps 32 of the transformer Mi When the rear truck of the train has reached a position say feet beyond the taps 32 of the transformer I6 sufficient current reaches the transformer through the rails IE to cause re-energization of the related relay I3. The operation of the signalcontrol circuits for governing the block signals as well as the inter section signals S is the same during train travel or movement in both directions on the track.

When the trainer car travels from the left to the right in Fig. l the transformer Hi is shunted out as described above when the train reaches a given position, but the transformer I9 does not become shunted out until the train reaches a position to the right of the transformer I6 In practice the transformer I9 may remain energized until the train reaches a position of, say, 60 feet from the transformer I9 at which point the train truck shunts out the transformer. Thus the transformers I6 and I9 are independently and successively de-energized .or controlled when the train travels from the left to the right.

Having described only a typical preferred'form and application of my invention I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art, or fall within the scope of the following claims.

Having described my invention, I claim:

1. A control for signal means-at the intersection of a highway and a track having conductively continuous rails, comprising relays for governing the signal means, two transformers connected across the rails at longitudinally spaced points and adapted to step up low voltage cur rent from the rails to current of higher voltage and each delivering the current to one of said relays to control the same, the transformers being at opposite sides of the intersection, and two current supply means connected with the rails at spaced points spaced between the transformers, each of said current supply means delivering current of just sufiicient potential to overcome the said rail resistance between it and the nearest transformer with a residual Voltage transmission to its nearest transformer for the control of the relay connected therewith and to provide a circuit in the rails capable of being'shunted out by a train truck within a known limited zone extending in one direction beyond the point of feed to the rails and extending in the other direction beyond the point of connection of the said nearest transformer with the rails, the said circuit zones of the current supply means overlapping throughout a rent supply means connected with the rails at spaced points spaced between the points of connection of the transformers with the rails, and low impedance bonds connecting the rails at points spaced beyond the transformers, each of said current supply means delivering low voltage current to the rails of sufficient potential to control a relay through the medium of the nearest transformer and related to the rail andbond resistances to provide a current flow circuit zone extending along the rails in one direction from its point of connection with the rails to the closest of said bonds and extending along the rails in the other direction toward the point of the connection of the other current supply means with the rails and being a zone within which a train truck may shunt out the circuit to affect the relay supplied with current by said supply means, saidzones of the spaced ciurent supply means overlapping in a portion of the track between the points of connection of the spaced current supply means with the track whereby both relays may be concurrently affected by a truck on the track between said current supply means, the rails being electrically independent except for said bonds and the said transformer and power supply means connections,

3. A signal system for use in connection with a track having electrically conductive rails comprising signals arranged along the track to guard blocks thereof, and control systems for the several blocks each comprising two relays for controlling the signals, a transformer connected with the rails in spaced relation to each endof the means connected with the rails at spaced points spaced between the transformers and each delivering low voltage currentrelated to the rail resistance to provide for the control of the relays through the medium of the nearest transformer and to create a Zone on the rails extending toward the input of the other supply means in which a, train truck may shunt out the said nearest transformer, the said zones of the spaced supply means overlapping along the rails in a portion of the track between-the two current supply'means, and low resistance bonds connecting the rails at points between the transformers of adjacent blocks, the rails being conductively continuous throughout the series of blocks.

4; In combination, a track having conductively continuous rails, a plurality of signal means, a relay for governing each signal means, two transformers connected across the rails at points spaced longitudinallyof the track' and each capable of receiving low voltage current from the' rails and stepping up the voltage for the control of a relay, two current supply means connected with the rails at spaced points and between the points of connection of'the transformers with the rails, each of said means supplying current to the rails of low voltage to energize the nearest of said transformers and to create a zone extending along the rails toward the other supply means in which a train truck will shunt out the said transformer, the said zones of the two supply means overlapping in a portion of the track between the spaced supply means, and a third transformer connected across the rails at a point between one of the first named transformers and a supply means receiving track current supplied by the last named means and controlling a relay, l

the resistance of the third transformer across the rails being greater than the resistance of the 1 adjacent first named transformer to be affected by train truck movement along a zone onthe rails shorter than the rail zone controlling said adjacent first named transformer.

5. A signal system for use in connection with a track having conductively continuous rails comprising signals arranged along the track to guard blocks thereof, and control systems for the several blocks each comprising two relays for controlling the signals, a transformer connected with the rails in spaced relation to each end of l the block, each transformer delivering control current to one ofsaid relays, the transformers being operable to receive low voltage current from the rails and convert it to current of sufficient voltage for the control of the relays, and two our-- rent supply means connected with the rails at spaced points spaced between the transformers and each delivering low voltage current related to the rail resistance to provide for the control of the relays through the medium of the nearest transformer and to create a zone on the rails extending toward the input of the other supply means in which a train truck may shunt out the said nearest transformer, the said zones of the spaced supply means overlapping along the rails in a portion of the track between said supply means, and low resistance bonds connecting the rails at points between the,transformers of adjacent blocks, the points of connection of each o said o d t the l be ns-c is. d a nal relation to the rails and each bond having a resistance greater than that of the train truck shunt which comprises said truck and the portions of the rails between said truck and the points of connection of the adjacent transformer with the rails when said truck is between the center of the bond and the adjacent transformer, the points of connection of the transformers with the rails being in diagonal relation to the rails and being so related that lines drawn through them are in substantially parallel relation to the adjacent bonds whereby the adjacent t1'an s.

formers are both shunted out when the truck passes over the bond.

6. A signal system for use in connection with a track having electrically conductive rails com-: prising signals arranged along the track to guard blocks thereof, and control systems for the several blocks each comprising two relays for controlling the signals, a transformer connected with the rails in spaced relation to each end of the block for delivering control current to one of said relays, the transformers being operable to receive very low voltage current from the rails and convert it to current of suflicient voltage for the control of the relays, and current supply means connected with the rails between the transformers and delivering low voltage current related to the rail resistance to provide for the control of the relays through the medium of the transformers, andbonds connecting the rails at points between the transformers of adjacent blocks,: the

pointsotconnection of the bonds with the rails being in diagonalrelation to the rails and the impedances of the primaries of the transformers and the aggregate impedance of the adjacent bonds and the rail portions between the bonds and the adjacent transformers being so related that the passage of a car truck over a substanial portion of the track between the ends of a diagonal bond causes concurrent de-energization of the-relays supplied by the two adjacent transformersduring such passage of the truck.

'7. A circuit controlling system for use in conneetion with a track having ccnductively con.- tinuous rails vcomprising two relays for the control of said circuits, a low resistance bondconnecting the rails, and control circuits for the relays, each control circuit including input leads connected with the rails at points spaced from the bond and delivering low voltage current to the rails, the input leads of said control circuits being connected with the rails at opposite sides of the bond and each control circuit including a transformer connected with the rails between the bond and the input leads of its control circuit operable to receive low voltage current from the rails and convert it into current of sufficient voltage for the control of a relay, the points 01 connection of the bond with the rails being in diagonal relation to the rails whereby both relays are shunted out when a train truck is passing over 30 the bond.

SAMUEL E. MCFARLAND.

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