US2082162A - Train dispatching system for railroads - Google Patents

Description

J1me 1937. F. B. HITCH COCK ET AL 2,082,162

" TR AIN DISPATCHING SYSTEM FOR RAILROADS Filed March 9, 1929 5 Sheets-Sheet l imagawww 6M2,

S'Shets-Sheet 3 F. B. HITCHCOCK ET AL TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed March 9, 1929 June 1, 1937.

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TRAIN DISPATCHING SYSTEM FOR RAILRQADS Filed Mafch 9, 1929 5 Sheets-Sheet4 mmwazzww, Y Y

ATTORNEY June 1, 1937. 7 F. B. HITCHCOCK ET AL 2,982,162

I TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed March 9, 1929 5 Sheets-Sheet 5 263 FIG. 3.

patented June 1, 1937 UNITED STAES PATENT OFFICE TRAIN DISPATCHING SYSTEM FOR- RAIL- ROADS Application March 9, 1929, Serial No. 345,667

24 Claims.

This invention relates to a train dispatching system of the type, in which the dispatcher can control distant switch machines, and in which trains are dispatched by wayside signal indications, and in which the indications controlling the signals and switch machines, and indications of the progress of I trains, are transmitted over a comparatively few line wires, by apparatus of the synchronous selector type.

In order that a dispatcher may properly dispatch the movement of trains, he should have control over the switch machines and signals, such that they may be moved in rapid succession, which results in the necessity that he should from time to time be informed as to the progress of said trains along the track. This indication of train progress is known in signal parlance as OSing train movements. It is understood by those skilled in railway practice, that OS indications may come in simultaneously and in close ly spaced or overlapped relations, and for this reason a synchronous selector type system, for transmitting such OS information, lends itself to this function admirably, this being because a a synchronous selector type system permits the transmission of a very large number of distinctive indications over the same line wire within a very short period of time.

However, there are limitations to the extent to which a synchronous selector of the rotary arm type may be used. This is because there is a limit to the size to which a rotary selector may be built, thus limiting the number of what we shall term message channels, also the necessity for speed, limits the size or compactness, as well as the ruggedness that may be built into such a selector. Also, such selectors must be built for a given number of message channels, which means that a need for additional channels, would require all existing selectors to be replaced by new ones.

In view of the above considerations and others, it is proposed to use for dispatching purposes in accordance with the present invention, a selfstepping synchronous selector system, in which the rotary arm selector, such as set forth in the patent to R. C. Leake, Patent No. 1,794,628 dated March 3, 1931, is replaced by a sufiicient number of relays, both in the dispatchers oflice and in each way-station, to set up the required number of message channels. In accordance with the present invention, it is proposed to transmit a plurality of alternate positive and negative impulses over the stepping circuit, including the stepping wire and the common return wire, of

which, each impulse will energize and move one of the above mentioned relays in the dlspatchers ofiice and one in each way-station, and during that period of time which exists between the movement of two successive relays, either a conway-stationyand also, the system as proposed,

stops automatically at the end of the period of time that is required to transmit all of the indications, which period of time may be no shorter than two complete cycles. Other features of the present invention reside in the construction and 1 arrangement of parts to establish synchronism between the banks of message channel selecting relays at various way stations and with the dispatchers bank of message channel selecting relays, as well as the added feature of a novel circuit, so arranged, as to permit the use of a comparatively small number of relays to give the number of message channels desired. I

Other objects, purposes and characteristic features of the present invention will in part be obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

In describing the invention in detail reference will'be made to the accompanying drawings, in which:-

Fig. 1A and Fig. 1B placed end to end, illustrate conventionally the equipment in the dispatchers oflice of a simplified system, illustrating the apparatus for controlling the switch machines and signals at one end of a passing siding;

Fig. 10 illustrates the equipment of one way station with the apparatus conventionally shown connected to the control relays for the switch machine and signals at one end of a passing siding; Fig. 2C illustrates the equipment of a way station showing a modification of the connections that may be used, so that a large number of message channels may be set up with comparatively few relays;

Fig. 3 illustrates in a symbolic manner the various combinations of contact positions and the message channels obtained thereby for message channel selecting relay bank shown in Fig. 2C; and

Fig. 3A illustrates diagrammatically the symbolic showing of the combination 8 of Fig. 3.

Description of apparatus Although in practice the dispatcher controls the switch machines and wayside signals of a large portion of a railway system, possibly including many passing sidings, diverging routes, draw bridges, railway crossings, and the like, the present invention has for convenience been shown as applied to the apparatus located at the west end of the passing siding PS (see Fig. 10) connecting to the main track TK of a single track railway system, signalled with absolute-permissive-block signalling to the track section, preceding the track section (as shown in Fig. 1C) enclosed by the insulated joints I82. The west end of this passing siding contains the track switch TSW This switch has associated therewith the usual detector track circuit insulated from the rest of the track by insulating joints I82, and included therewith the fouling section PS of the passing siding PS connected by wires I89 and H98 in the usual manner. This detector track circuit contains the usual track battery I9 I and track relay TR The starting signals for the main track and siding at the west end of the passing siding PS have been designated SW and SW respectively, and the corresponding entering signals have been designated SE and SE In the tower is preferably located a miniature track layout corresponding in every detail to the system over which the dispatcher has control, and in the particular arrangement shown includes only the passing siding PS. This miniature track layout has an indicating lamp I associated therewith, which if illuminated indicates the occupancy of the corresponding detector track circuit, namely, the detector track circuit containing the track relay TR The track switch TSW at the west end of the passing siding PS is preferably controlled by a switch machine SM which switch machine is preferably controlled by the switch machine relay SMR which relay is in turn controlled by the lever SML through the medium of the self stepping synchronous selector system hereinafter described. Similarly, the signals SE SE SW and SW are controlled by the signal relay SR and the direction relay DB through the medium of the synchronous selector system in accordance with the position of the lever SL located in the dispatchers ofiice.

With the drawings, Fig. 1A and Fig. 1B placed end to end, we have an illustration of the dispatchers office, having a bank of message channel selecting relays l to I l inclusive, which are controlled through a line relay LP, by alternate positive and negative impulses set up by a master relay MR, and two time spacing repeater relays S and S The master relay MR and its spacer relays S and S are interconnected to produce a non-mechanical rotation, which results in a positive or a negative impulse being placed on a stepping wire Zfil when the relay MB is in its corresponding energized position. The operation, of this impulse generating group of relays, is controlled directly by a control repeating relay CRR which is in turn controlled by a control relay CR and an initiation relay IN, which is initiated either by a movement of a control lever such as SL or SML, or by'connecting a message wire 202 with a common wire 299 while the system is at rest.

The dispatchers ofilce equipment is connected to a way station equipment or equipments such as illustrated in Fig. 1G by three line wires consisting of a common wire 209, a stepping wire 20!, and a message wire 262. The way station as illustrated in Fig. IC has a line relay L connected in series in the stepping wire 26! and with the line relay L in the dispatchers oilice. The line relay L controls its bank of channel selecting relays I to i inclusive. It is obvious that the operation of the channel selecting relays to l in the way station will be in synchronism with the channel selecting relays i to H in the dispatchers ofiice, due to the fact that the line relays L and L are connected in series and by reason of the similarity of their circuit connections. With the system initiated and the relays I to H inclusive being operated sequentially and in synchrcnism with the relays i to l inclusive, a control, or other indications may be sent, or received, over a predetermined message channel, which occurs at a predetermined time in the operation cycle of the sequentially operated message channel selecting relays.

For convenience. in explanation of the circuits and relays involved therein, the relays of the same type have been given characteristic letters having the individual relays distinguished by suitable exponents, with each type of relay having the characteristic features as briefly summarized below, with any variations to meet a specific case, mentioned where that specific example is set forth.

(1) The relays i to 67 inclusive, Figs. 1A and IB, the relays, l to l inclusive, Fig. 1C, and the relays A, B, C and D, and X, Y, and Z, Fig. 20, used to produce the non-mechanical rotation by successive relay movements, are of the polar permanent magnet stick type. In other words, when an energy impulse of a certain polarity has been applied, and has moved its contacts to the position determined by the polarity, a permanent magnet incorporated within the relay holds the armature in that position. The OS relay and the relays S and S are also of the polar stick type.

(2) The line relays L and L are polar, biased to neutral, type relays, which respond in such a manner that their contacts are held in neutral or non-contact-1naking positions during the time that no energy is applied, but are moved either to the right or to the left as positive or negative impulses, respectively, are applied.

(3) The relays ST", ST etc. are neutral relays, having the characteristic feature that they do not pick up upon application of impulses, which are of the normal rate, sent over the stepping circuit; but upon application of a long impulse their armatures are picked up within a predetermined period of time, which period of time is a predetermined fractional part of the total duration of the long impulse.

(4) The relays IN, IN etc. are neutral relays, which may be either quick or slow acting during their release period, as the necessity of a specific case demands.

(5) The relay OR is a neutral relay with two windings, so designed that the armature will pick up with a certain normal value of current flowing in either winding.

It will be stated here, that each polar relay is considered to assume a right hand or positive position, with an application of positive potential to the left hand terminal of the relay, and to assume a left hand or negative position, with an application of negative potential to the left hand til terminal of the relay. It is also assumed that the normal positions of all relays are their present full line positions, so that when a relay is spoken of as being in a reverse or abnormal position, it shall mean the dotted position as shown in the accompanying drawings.

The levers I8, I9, and 20 are connected together mechanically, as are also the levers 2I and 22, so that the movement of the controlling handles SL or SML, respectively, will move the inter-connected levers together. It will be observed, that the levers I8 and 2i make contact with the common wire at points I86 but momentarily, as the levers are moved to their dotted line positions.

It is believed that the features of the system will be better understood by considering its operation.

Operation The apparatus and circuit arrangement embodying the present invention may be divided into two distinct groups, as follows: (1) The stepping, or synchronizing circuit arrangements and mechanisms which have a major function in producing a non-mechanical rotation by successive relay movements occurring in exact synchronism, and which provides that the system shall be normally at rest, but shall be initiated for synchronous rotation of relay movements, either, when the dispatcher operates a lever to control a distant function, or when an OS indication is present at a waystation ready for transmission to the dispatchers office, and to be stopped at the end of the second cycle if there are no further indications to be transmitted; (2) a message channel circuit arrangement and mechanisms, which have a major function of utilizing the non-mechanical rotation of successive relay movements in producing temporary message channel circuits, which are completed during the period of time intervening between the final movement of one relay and the initial movement of the next relay in succession, which message channel circuits are to be used for transmitting impulses either for OS indications or for controlling switch machines, way side signals, de-rails and the like.

Operation of the synchronizing circuits As has been explained, the line relays L and L are energized by the impulses which are impressed on the stepping wire 25. These line relays serve to repeat for the local circuits, the impulses passed over the stepping wire, so that the message channel selecting relay banks may be synchronously operated.

These message channel selecting relays are of the polar stick type, which have the required number of contacts to meet the needs in a specific location in the circuits. The first two of these contacts are break and make beyond center, for use in the operating circuits of the relays. In other words, the circuit for operating each relay, is carried through one of two of its own contacts, so that one contact must break and make beyond center, when the contacts are moved in one direction, and the other contact make and break beyond center when the contacts are moved in the other direction. This is to insure that no relay shall become stuck on center.

The message channel selecting bank of relays is so organized, that the movement of one relay to a given position, opens its own circuit and closes the circuit for the next relay to be operated. This means that the polarity of successive relays must be alternated, so that an impulse,

which operates a given relay, willnot operate the next relay in succession, when its circuit is closed, but rather must require an impulse of the opposite polarity. With this organization of apparatus every impulse produces a definite predetermined result, which as applied to the banks of relays as shown in Figs. 1A, 1B and 10, determines that the number of relays in the banks shall be an odd number, so that every impulse shall be an active one.

The relays I to I! inclusive, and the relays I to I inclusive, operate in identical fashion, such that impulses alternately negative and positive, placed on the wire 22%, connected to the contact 32 of relay I (see Figs. 1A and 1B) and the wire 228 connected to the contact I 88 of relay I (see Fig. 1C) energize the successive relays in succession to reverse positions. Also, impulses, alternately positive and negative, placed on the wire 226 connected to contact 33 of relay I, and on the wire 229 connected to the contact I09 of relay I energize the successive relays in succession to their normal positions. Thus, the circuit arrangement is so organized that relay I moves its contacts to a negative position with a negative impulse, relay 2 moves its contacts to a positive position with a positive impulse, and relay 3 moves its contacts to a negative position with a negative impulse, and in like manner all relays operate to a reverse position.

More specifically it will be stated, that alternate negative and positive impulses applied to the stepping wire 20I, are repeated by the relay L in such a manner that alternate negative and positive impulses are placed upon wire 228 receiving energy from battery I81 and I88 through contact I04. These impulses are routed, so to speak, through the wire 228 to the contact tilt of relay I I. This contact directs the impulses on either wire 224 or wire 226, according to its position.

Let us assume, that a negative impulse is placed on the wire 224. This impulse passes through positive contact 32, through relay I, to common, thus moving its contacts to a negative position. Should that negative impulse on the wire 22d continue after the relay I has moved its contacts to the negative position, that impulse would be applied to relay 2, through its negative contact 35, but since relay 2 is already in the negative position, the negative impulse will not efiect its movement. However, the positive impulse which is next placed on wire 224 flows through negative contact 32 and negative contact 35, through relay 2, which moves its contacts to a positive position. Should that positive impulse continue after the relay 2 has moved its contacts to a positive position, that impulse would be applied to relay 3 through positive contact 39, but as relay 3 is in a positive position it does not affect movement thereof. The negative impulse next placed on wire 22 i flows through this circuit in suchv a manner as to move the contacts of relay 3 to a negative position, and in like manner as positive and negative impulses are placed on the wire 224, the relays in the bank are successively moved from their normal full line position, to their reverse dotted line positions, until the last relay and return relay I to its normal position. The movement of relay I to a positive position, sets up the circuit for relay 2 through positive contact 36. But relay 2 is at this time in a positive position and does not respond to that positive impulse even if it should be indefinitely prolonged. However, the next successive impulse, which is negative, moves the contacts of relay 2 to a negative position, thus setting up the circuit for relay 3. In like manner, the relays I to I 6 inclusive are returned to their normal positions.

The relays I to II, as shown in the drawings, Figs. 1A and 1B, are assumed to have been reversed and relays I to It to have been returned to their normal positions thus leaving the circuits as shown in the drawings. With such a condition obtaining, a circuit is made up for the positive and negative impulses repeated at contact IM, as follows:through wire 228 negative contact I09, wire 226, positive contact 33, negative contact 36, positive contact 40, negative contact 44, positive contact 48, negative contact 52, positive contact 56, negative contact 80, positive contact 64, negative contact 68, positive contact I2, negative contact I6, positive contact 88, negative contact 84, positive contact 89, negative contact 94, negative contact 99, wire 221, through relay ST" to common. As has been explained heretofore the relay ST does not pick up upon the impulses of the normal stepping rate, so that the relays must stop at the end of each cycle, because no release can be obtained at the end of the cycle of a relay bank until the corresponding relay ST or ST has been picked up.

It will be noted here, that it is desirable that the system shall go through at least two cycles after it has been initiated, and then cease operation providing that all OS indications have been received. In order to accomplish this, the circuits of relays IN and CR are so arranged, that when the relay IN is energized the relay OR is energized. This means that, as the system is approaching the end of a cycle, the stick circuit of the relay CR must be opened preceding the opening of the stick circuit of the relay IN, so that the relay CR will not drop, as will the relay IN at completion of the first cycle, but will drop at the end of the second cycle, To do this, the contact 9'! has connected in parallel with it the contact I94, in such a manner, that the resulting combination, of the two contacts is such,

that the stick circuit of the relay IN is completed through either contact 91 or contact I94, except during the period of time that exists after the initiation of contact 9'! toward its normal position, and the time that the contact I96 again assumes a reverse position. This may be explained by saying that, with the relays l6 and IT with their contacts in the present normal positions, contact will be made, when contact I94 is moved to a positive position, so that wire 2I8 is then connected to common wire 280, through Wire HI and positive contact 596, but when normal contact 97 is reversed, the wire 2I8, is connected to the common wire 2%, through positive contact 91. Then, with the next relay movement, which is the movement of the contacts of relay IT to a negative position, the circuit from wire 2I8, through positive contact 91, to the common wire 200 is still made, although broken at contact I94. However, on the next half cycle when the relays return to their normal position, the circuit through positive contact 97, is broken, and is not again made until the contact I94 returns to a positive position. Thus, it is seen that the circuit under consideration is broken only at one time, which time is at the end of each cycle completed by the message channel selecting bank of relays I to H inclusive.

In the same manner, the stick circuit for the relay CR has the contact 8'! connected in parallel with contact 92, which thus accomplishes the same result, as the contacts 91 and I9 1 connected in parallel accomplish for the stick circuit of relay IN. The stick circuit of the relay CR is momentarily open during a period of time preceding that period during which the stick circuit of relay IN is open. It will now be seen that upon nearing the completion of the first cycle of the non-mechanical rotation, as the relay I4 has returned its contacts to the normal position, the stick circuit for the relay CR is broken, but the relay CR does not drop due to the fact that the current for the relay IN flows through its upper winding. Upon movement of the contacts of relay I5 to their normal position, the stick circuit for the relay CE is again closed, and the stick circuit for the relay IN is opened upon movement of the contacts of relay I6 to their normal position, which immediately drops the relay IN. The relay IN remains de-energized due to the dropping of its front stick contact 23. As the rotation of the message channel selecting bank of relays nears the completion or" its second cycle, the stick circuit for the relay GR is again opened, and the relay CR drops due to the fact that the relay IN has formerly been de-energized.

The control relay CR, as its name implies, controls the initiation and stopping of the impulse generating group composed of relays MR, S and S But in order that the starting condition may be fulfilled, namely, a long positive impulse to pick up the relay ST and ST etc., a control repeating relay CRR. is interposed in the control, to produce the long positive impulse upon the stepping wire 20L During the period of time which exists after the relay CR has been energized, and before the relay CRR picks up, there is a circuit completed which places positive potential upon the relay MR. Thus, a positive impulse is placed upon the stepping wire 2IlI. This positive impulse is maintained until the relay ST has picked up and the relay I! has moved its contacts to a positive position, thus closing a circuit for picking up the relay CRR. The picking up of relay CRR reroutes the stick circuit of the relay IN through the front contact I95 to the wire 258, which is connected, at this time, to the common wire 290. Also, the relay CRR must be slightly slow releasing, sufiiciently to prevent the back contact I95 to make, before the front contacts 23 and I9! of the relay IN break. Failure to do this would cause the system to continue operation after the end of the second cycle.

The picking up of the relay CRR cuts off the positive potential applied to the relay MR, through back contact I 65, and closes front contact I06. The closing of contact I86, gives a potential to the relay MR as determined by the position of relay S The long positive potential on relay MR moved its contacts to a positive position, which energized the contacts of relay S to a positive position, which, with said contacts of relay S in such a position, energizes the contacts of relay S to a negative position, thus placing negative potential on the relay MR when front contact I06 of relay CRR is closed. With negative potential on relay MR, its contacts assume a negative position, which energizes the relay S to move its contacts to a negative position, which in turn energizes the relay S to move its contacts to a positive position, placing positive potential on the relay MR. Thus we have shown how the successive operation of the relays MR, S and S occur, to produce alternate positive and negative impulses used for stepping.

It will be noted here that the time interval of these impu se-s is determined by the operating time of the relays included within the impulse generating group. Also, it is seen that this group can not get ahead of the line relays, as the relay S is in series with said line relays.

We will now assume that all the apparatus in the dispatchers office and in the way station (as illustrated in Figs. 1A, 1B and 1C, placed end to end) to be at rest. To illustrate the starting of the apparatus, the revolving of the message channel selecting relays in a non-mechanical rotation, to illustrate how the alternate positive and negative impulses are produced by the impulse generating group, operating in a non-mechanical rotation, and to show the results of the movement of a control lever, we will assume that the dispatcher desires to move the switch TSW from the normal position to a reverse position routing the east bound main-line traffic onto the passing siding PS The movement of the track switch TSW is controlled by the switch machine SM associated therewith, which is in turn controlled by the switch machine relay SMR With the polar contact of the relay SMR in a right hand or positive position, the switch machine operates so that the switch TSW assumes a normal position allowing east bound traflic to proceed upon the main track, and with the polar contact of relay SMR in a negative orleft hand position the switch machine SM operates to move the track switch TSW to a reverse position allowing the east bound traffic to proceed onto the passing siding PS The position of the polar contacts or" the relay SMR is determined by the position lever SML by means of a control impulse transmitted to the relay SMR through the medium of the synchronous selector system hereinafter described.

We will now assume that the dispatcher moves the lever .SML to negative position. During the movement of this lever to a negative position, the lever 2i makes momentary contact IBiS which sets up a circuit as iollows:--from positive battery 5-33, through wires 233, ZI'I', 2I6, and '2 I5, through the upper winding of relay CR wire 2H5, relay IN, wire Eli-s, lever 3, contact iilli, to the common wire This momentary circuit energizes the relays IN and CR, in as much as the current that flows in this circuit passes through the upper winding of the relay CR and the winding of relay IN connected in series. These relays CR and Ill are held ene zed through stick circuits completed by their front contacts 25 and 23 respectively. The stick circuit for the relay IN may be traced U ilows:-positive battery from battery througn wires 203, 2H, 2M5, 2E5, relay CR, wire relay IN, wire 223, front contact 23, 2923, back contact 995, to the common wire The stick circuit for the relay CR may be traced as fo1lows:positive battery from the battery 82, wire 2%, Ell, H3, and 2H), lower winding relay CR, front contact i l, wire 2W, positive contact 92, to the common wire 2%.

The energization' of the relay CR causes positive potential to be applied to the relay MR through a circuit traced, as follo-wsz-positive battery from the battery I83, wires 283, Ml, 2I6, 224, 225, negative contact Hi2, wire 7226, back contact I05, wire 221, front contact 26, wire 218, through the relay MR to the common wire 200. This positive potential applied to relay MR moves contacts 21 and 28 to a positive position. With contact 21 in a positive position a circuit is set up as follows:positive battery from battery I83, through wires 2M, positive contact Zl, wire 279, relay S wire ZIlI, relay L wire 2M, relay L to the common wire 2%. With this circuit closed, current flows through the windings of relays L and L to move their contacts to a positive position.

With the contact I34 of relay L in a positive position, positive potential is placed on the relay ST through a circuit traced as followsz-positive battery from battery I31, through wire 228, negative contact IDI) of relay Ill, wire 225, positive contact 33 of relay I, negative contact 36 of relay 2, positive contact M] of relay negative contact 44, positive contact 48, negative contact 52, positive contact 56, negative contact til, positive contact 64, negative contact 68, positive contact I2, negative contact I3, positive contact 89], negative contact 84, positive contact 89, negative contact 94, negative contact 99, wire 22l, through the relay ST to common; During the time that the contact I04 of relay L is in a positive position this circuit is maintained so that the relay S'I will pick up in a predetermined length of time, which is slightly greater than the pick up time of relay ST At the same time that the relay ST is picking up due to the positive potential being placed upon it, the relay ST is being picked up through a circuit traced as followsz-positive battery from battery I98, positive contact Hill, wire 230, negative contact I34, wire 229, positive contact I09 of relay I negative contact I I3 of relay 2 positive contact II'I of relay '3 negative contact I2I of relay 4 positive contact I25 of relay 5 negative contact I29 of relay 6 negative contact I33 of relay I through the relay ST to common. As the relay ST requires less time to pick up than the relay ST", said relay ST will close its front contact I36, allowing positive potential flowing from the battery I38 through the circuit just traced for relay ST to be also placed upon the relay I through front contact I 35, wire 23L through relay I to common, thus energizing the relay I so that its contacts move to a positive position. Similarly, the relays of the type ST in all other way stations of such a system will pick up and allow the last relay of the message channel selecting group over which they control, to be energized to a'positive position.

As soon as the relay ST picks up its front contact I03, a circuit is completed so that positive potential from the battery I81 flows through the circuit heretofore traced for the relay ST, being shunted from the relay ST through the front contact I03, wire 280, through relay I I to common. Thus the contacts of relay 51 are moved to a positive position.

The movement of the contacts of relay I! to a positive position, opens the circuit (heretofore traced) at the contact I32 of relay 1?, for placing the positive potential on the relay MR. Also, as soon as the contacts of relay Il assume positive position a circuit is completed which energizes the relay CRR through the circuit traced as 01- lows:positive battery from battery I83, through Wire 203, 2H, 222, front contact 25, wire 223, to relay CRR, wire 2| 8, and 22I positive contact I 94 of relay IT, to the common wire 200.

With the relay CRR energized, its front contact I05 closes a circuit, which permits a potential of a polarity as determined by the position of contact 29 of relay S to be placed upon the relay MR. The relay MR having been previously energized with a positive potential, causes the contacts of relay S to assume a positive position through a circuit heretofore traced. With the contact 30 of relay S in a positive position a negative potential is placed upon the relay S through a circuit traced as follows:--from the negative battery I 84, through wires 208, 209 and 2I0, positive contact 30, wire 2, through the relay S to the common wire 200. Thus the contact 29 of relay S is energized to a negative position. When the relay CRR is energized, and its front contact I06 is closed, the potential placed upon the relay MR is negative and flows through a circuit traced as follows:from negative battery I84, wires 208 and 209, negative contact 29, wire 206, front contact I06 of relay CRR, wire 218, through the relay MR to the common wire 20!]. This negative potential placed upon the relay MR causes its contacts to be moved to a negative position, causing the result that a negative potential is placed upon the relays S L and L in series through a circuit traced as follows:from negative battery I84, through wire 2I2, negative contact 21, wire 219, relay S wire 20I, relay L, wire 20I, relay L to the common wire 200.

The energization of relay CRR, also re-routes the stick circuit of the relay IN through a circuit traced as follows:positive battery from the battery I83, through wires 203, 2I'I, 2H5 and 2I5, relay CR, wire 2I4, relay IN, wire 228, front contact 23, wire I96, front contact I95, wire v2IiI, front contact I91, wire 260, and H8 and 22 I, positive contact I94 of relay IT to the common wire 200.

With a negative potential on the relay MR due to the energization of the relay CRR, a negative potential is placed upon the relays S L and L which moves their contacts to a negative position. With the contact I04 of relay L in a negative position a circuit is set up which places negative potential on the relay I, being traced as follows:from the negative battery I88, through negative contact I04, wire 228, positive contact I88 of relay I'I, wire 224, positive contact 32 of relay I, through the relay I to common, thus energizing the relay I to move its contacts to a negative position. At the same time the contact I07 of relay L is in a negative position, which places negative potential upon the relay I through a circuit traced as follows:- from negative battery I99, through negative contact I01, wire 230, positive contact I34, wire 228, positive contact I08, through the relay I to the common wire 200. The relay I is thus energized to move its contacts to a negative position. Also, at the same time, the contact 35, of relay S is in a negative position which completes a circuit to place positive potential on the relay S with the circuit being traced as follows: from the positive battery I83, through wires 203 and 284, negative contact 30, wire 2| I, through relay S to the common wire 200. Thus the contact 29 of relay S is caused to move to a positive position which results in a positive potential being placed upon the relay MR through a circuit traced as follows:from the positive battery I83, through wires 233, 204, and 205, positive contact 29, wire 286, front contact I05 of relay CRR. wire 218, through the relay MR to common. Thus, the contact 21 of relay MR is moved to a positive position, placing a positive potenial upon the relays S L and L through a circuit as heretofore traced.

It will be here pointed out that as the relays S L and L are in series they will operate at the same time, provided that they are built with the same operating characteristics. This being so, the relay S will operate its contacts at the same time that any message channel selecting relay operates its contacts, thus causing the result that as soon as a message channel selecting relay has been energized in the dispatchers office and corresponding message channel selecting relay has been energized at each way station simultaneously with the energization of the relay S then the relay MR is energized to an opposite position. Thus in like manner the impulse generating group of relays composed of relays MR, S and S proceed to operate in a non-mechanical rotation until their circuit is again opened at the contact I06 of relay CRR.

The next impulse which is produced by the relay MR, is repeated by the line relays L and L As the last impulse was negative and moved the contacts of relays I and I to a negative position, then the next impulse is positive and is repeated by the relay L in the dispatchers ofiice, which establishes a circuit traced as follows:-- positive battery I87, through positive contact I94, wire 228, positive contact I00, wire 224, negative contact 32, negative contact 35, through the relay 2, to the common wire. Thus the contacts of relay 2 are energized to the positive position. Likewise the positive impulse repeated by the relay L in the way station shown in Fig. 1C flows through a circuit traced as follows:- from positive battery I98, through positive contact I97, wire 235, positive contact I34, wire 228, negative contact I08, negative contact II 2, through the relay 2 to the common wire. Thus the contacts of relay 2 are moved to a positive position.

With the relays 2 and 2 in positive positions a circuit is set up during a central portion of the total channel time, as explained hereinafter which allows negative potential to be placed on the relay SMR being traced as follows:- from the negative battery I84 through wires 200, 233, lever 22 in a left hand position, wire 235, positive contact 37, of relay 2, positive contact M of relay 3, negative contact 45 of relay 4, positive contact 49, negative contact 53, positive contact 51, negative contact 6|, positive contact 65, negative contact 69, positive contact I3, negative contact 'I'I, positive contact 8|, negative contact 85, positive contact 90, negative contact 95, positive contact IEII, through wire 232, positive contact 3 I, wire 236, negative contact 28, Wire 2532, to the Way station, wire 24L positive contact I35, negative contact I30, positive contact I25, negative contact I22, positive contact H8, positive contact II 4, through the relay SMR to the common wire 200. Thus the polar contact of relay SMR is moved to a negative position effecting a control of switch machine, which in turn moves the switch TSW to a reverse position routing the east bound traffic onto the passing siding PS.

The succeeding negative and positive impulses sequentially operate the relays 3, 4, 5, 6, I, 8, 9,

I II, II, I2, I3, and I4 to their respective reverse positions, in a similar manner as explained for relays I and 2. When the contacts of relay I i assume a reverse position, the contact 81 completes a circuit in parallel with contact 92, so that the next impulse which is negative and moves the contacts of relay I5 to a reverse position, does not open the stick circuit of relay CR. Likewise the next positive impulse which energizes the contacts of relay I6 to a reverse position, moves contact 91 to a reverse position which completes a circuit in parallel with contact I 94, so that although the circuit through the contact IS of relay I7 is broken upon the application of the next negative impulse, the stick circuit for the relay IN, and the energizing circuit for the relay CRR is still maintained. Now that the relays I to II inclusive, have gone through onehalf their cycle, the contacts of relay II are then in a negative position, which routes the stepping impulses through the wire 226 instead of wire 224, so that the relays I to I Ii may be returned to their normal positions, and it is assumed that they are so returned. During this second half cycle, these relays are returned to their normal position sequentially, and when the relay I l returns to its normal position the stick circuit for the relay CR was opened and again closed upon movement of relay I5 to a normal position, but did not drop relay CR, due to the fact, that the current for relay IN was flowing through the upper winding of relay CR. With the relays I to I it in their normal positions, the circuit for picking up the relay ST is completed, and also the circuit including the relays CRR and IN in multiple is opened, thus dropping both the re lays CRR and IN. The dropping of relay CRR closes the circuit for placing a positive potential upon relay MR through the front contact 26 of relay CR and back contact I 85 of relay CRR.

Thus in due time, the relay ST again picks up and the relay I I is energized to the positive position, which again picks up the relay CRR, causing the generation of positive and negative impulses by the impulse generating relay group S S MR, which impulses are applied to the stepping wire 2III. The channel selecting relays complete another cycle during which time the relay CR, is deenergized by the movement of contact 8'! of relay I l to a normal position,

which is possible inasmuch as the relay IN is now deenergized. The dropping of relay CR also in turn drops the relay CRR, which has a slow releasing period to an extent that the impulse generating group will produce at least two'impulses after the stick circuit of relay CR has been opened. Thus two cycles of operation have been completed.

The operation of the control circuits for the relays I to I inclusive and the relay ST is identical to that explained for the relays I to I"! inclusive and the relay ST".

Let us now consider the synchronous operation of the message channel selecting bank of relays in the dispatchers office, in regard to their co-op-eration with a message channel selecting bank of relays at a way station such as shown in Fig. 10. As the long positive starting impulse picked up the relays ST and ST and the relays El and "i are energized to a positive position, the first negative impulse energizes relays I and I to a negative position. Likewise the next succeeding positve impulse energized relays 2 and 2 to a positive position, with each succeeding impulse energizing its respective corresponding relay, until relays 1 and '1 have been energized to a negative position. The next succeeding impulse is a positive impulse which energizes relay 8 to a positive position and relay I to a positive position. Likewise the succeeding negative impulse energizes relay 9 to a negative position, and relay 2 to a negative-position, until relay I3 has been energized to a negative position and the relay 6 has been energized to a negative position. The following impulses which are used in the dispatchers oflice to complete the cycle in the relays I to I! inclusive are absorbed at the way station in the relay ST without producing any relay operation. So it is easily seen that should the way station relays for any reason whatsoever, such as extraneous foreign impulses, or lack of immediate response of a relay, be out of step, that these extra impulses generated at the dispatchers omce, would bring the way station up to the end of the cycle. Thus, at the end of each cycle, the relays at the dispatchers ofiice and the relays at the way station are again synchronized.

It will be stated here that should the lever SL be moved to either of its extreme positions, the system would be initiated and impulses of a polarity corresponding to the positions of the levers I9 and 20 would be sent over their corresponding message channels, which are set up at a suitable time during the sequential operation of the message channel selecting relays, While they are completing one cycle. Let us as sume that the lever SL is in the right hand position, moving the lever contact I9 and ZIP to a right hand position which clears the signal SE allowing traffic to proceed in an east bound direction. The message channel for lever contact I9, assuming that the message channel selecting relays have been stepped to their proper positions, may be traced as follows:-positive battery from battery I83, through wires 2%, EH, ZIS, 224 and 234, lever I9 in a right hand position, wire 238, negative contact 34, negative contact 31, positive contact 4|, negative contact 45, positive contact 69, negative contact 53, positive contact 5?, negative contact BI, positive contact 65, negative contact 69, positive contact I3, negative contact all, positive contact SI, negative contact 85, positive contact 8G, negative contact $5, positive contact IIII, wire 232, negative c0ntact 3|, wire 23?, positive contact 28, wire 202, to the way station shown in Fig. 16, wire 248, positive contact I35, negative contact Itil, positive contact I26, negative contact I22, positive contact IIB, negative contact II I, negative con tact Hi3, through the relay SR tothe common wire m. Thus the relay SR is energized with positive potential which causes its polar contact to assume a positive position as shown. The message channel for the lever contact 26, assuming that the message channel selecting relays have been stepped to proper positions, may be traced as followsz-positive battery from battery I83, through wires ZI'I, 2H5, 22-6 and 234, positive lever 26, wire 25B, negative contact II, negative contact 55, positive contact t9, negative contact 53, positive contact 57, negative contact {I I, positive contact negative contact 59, posi tive contact I3, negative contact ll,positive contact 3|, negative contact 85, positive contact SII, negative contact positve contact IIPI, wire 232, negative contact SI, wire 231, positive contact 28, wire 202, to the way station shown in Fig, 1C, wire 2M, positive contact I35, negative contact I30, positive contact I26, negative contact 22, negative contact I !8, through the relay DB to the common wire 260. Thus the relay DB is energized with positive potential causing its polar contact to be moved to a positive position.

Let us again assume that the system is at rest, and that a train enters the track section TK The occupancy of track section TK shunts the track relay 'I'Pv so that its contacts I32 and 33 assume a de-energized position. As the contact is a make before break contact, a circuit is momentarily completed from the battery 28!] through contact 538 and the relay IN to the common wire 2%. This momentary circuit energizes the relay IN which is a slow releasing relay, having a release period sufficient to allow the system to complete one cycle before it is entirely de-energized. As the system is at rest, and the relay IN is energized, a circuit is completed through the contact l3? of relay IN which will initiate the system and is traced as follows:from the positive terminal of battery i823, through Wires 293, 291, 2H5 and H5, upper winding of relay CR, wire 2M, relay IN, wire 239, negative contact 92 of relay 15, negative contact 823 of relay ll, wire 202, to the way station shown in Fig. 1C, wire 245, negative contact E35, negative contact 13$, wire 2 59, front contact liil of relay IN, to the common wire 230. Thus a current flows through the upper winding of relay CR and the winding IN moving the contacts to an energized position, thus initiating the system and stepping the message channel selecting relays in sequential operation for completing two cycles for reasons heretofore explained. When the message channel selecting relays assume proper positions, which occurs once during each of the two cycles, a message channel is set up so that the OS indication, telling the dispatcher that the track section TK is occupied, may be transmitted. This message channel is traced as follows:negative battery from battery 288, through back contact E33, wire 28. positive contact I22, positive contact l28, negative contact I311, positive contact 135, wire 2 5i, Wire 2922, to the dispatchers office shown in Figs. 1A and IE, to the negative contact 28, wire 236, positive contact 3!, wire 232, positive contact .itl, negative contact 95, positive contact 92, negative contact 85, positive contact 8 l, negative contact ll, positive contact 13, negative contact 69, positive contact 65, negative contact 69, positive contact 51, negative contact 53, positive contact 49, positive contact 45, wire 282, through the relay OS to the common wire 200. Thus the polar contact I of the relay OS is energized to a negative position illuminating the indicator lamp I, giving indication to the dispatcher that the track section TK is occupied.

It will be noted here, that the number of relays in the dispatchers office was arranged for use with the modified way station as shown in Fig. 20. Thus, there is an excessive number of synchronizing impulses which are not practicable for the type of way station connections as shown in Fig. 1C.

When way stations, such as shown in Fig. 1C, are used in series, provisions must be made that each way station of this type must have an equal number of relays, which give the total required number of message channels. This is necessary, since, as soon as any one Way station comes to the at rest period, this station then has a message channel set up which is used for initiation. Should an OS indication occur at this particular station, then the message wire 202 would be connected to the common wire 20!] at this particular station, which condition would result in the extermination of any control indications which might be sent over the message wire for use at some other Way station, and for this reason it should be understood that all way station relay banks of a particular system should have the same number of channel selecting relays.

Operation of message channel circuits After having explained the synchronous operation of the channel selecting relays, we may now consider how contacts on corresponding relays in the two relay groups close synchronously to complete a plurality of sequentially closed message circuits. These sequentially closed circuits may be conveniently termed message channels, and the period of time during which they are closed, may be suitably termed total channel time.

It is possible, due to slight variations in characteristic operating time of the channel selecting relays for an overlapping of the total channel times to occur, which might cause an indication intended for one message channel to be indicated on two message channels. In eliminating this possibility, a circuit is provided which splits the total channel time into three periods and permits the indication to be passed into its own channel, only during the central period of the total channel time.

In a system, as shown in Figs. 1A, 1B and 10, this total channel time is divided into three periods by the relays MR, S and S The message wire is connected through the movable contact 28, of relay MR, so that a circuit may be completed through positive or negative contact 28 to wires 23'! and 236 respectively, through negative or positive contacts 3| respectively, to wire 232, which is then carried to the message channel selecting relay to be connected to the various message channels.

By way of illustration, we will assume that the operating time of relays MR, S and S are of equal length and equal to the operating time of a channel selecting relay such as relay I. Then relay S being in series with the relays L and L will operate during the same period of time as the line relays, also the relay S will operate during the same period of time as the particular message channel selecting relay which is then being operated will operate. Also, We will assume that the system has been initiated and the contacts 21 and 28 of relay MR have been moved to a positive. position by a positive potential being applied to the relay MR. This position of contacts 2'! and 28 energizes the relay S to a positive position as shown, but at this time the message circuit is broken at contact 3|. With the contacts of relay S energized in a positive position the contact 29 of relay S is energized in a negative position as shown. It will be remembered that the channel selecting relay operates at the same time as the relay S so that we may assume, that as soon as the contact 29 has reached a negative position, the period of time representing the total channel time has begun. With contact 29 in a negative position, the contacts of relay MR are energized to a negative position, at which time the message circuit is continuous from the message wire 202 through negative contact 28, wire 236, positive contact 3!, to wire 232, to any particular mes sage channel. It is seen that a period of time has elapsed since the beginning of the total channel time, and the instant that the contact 28 arrived in a negative position. The movement of contacts 2'1, 28 to a negative position energizes the relay S to move the contacts 30 and 3! to a negative position. At the initiation of the movement of contact 3%, the message circuit heretofore traced is broken, but the total channel time has not elapsed until the contact 29 of relay S has been initiated in movement toward a positive position by the application of a positive potential to the relay S Hence it is seen, that the message circuit is closed only during the period of time that it takes the current to build up sufficiently in the winding of relay S to initiate movement of its contacts, thus making it possible to regulate the indication or message time by increasing the characteristic operating time of relay S t will of course be understood that to apply this same principle of sending the message or indication during a time which is central in respect to the total channel time, to a way station where the stepping impulses are not repeated by a line relay, as in Fig. 20, the stepping impulses should not be repeated for the dispatchers message channel selecting bank of relays, and the contact 3i should be controlled by relay S instead of relay S The contacts of successive relays which close and open the message channels, are normally in alternate positive and negative positions, so that there is only one time that two successive contacts are in like positions. This may be illustrated by the relays l and 2. The message contacts 33 and 34 are in a positive position, the message contacts 3'! and 38 are in a negative position and the message contacts ii and 42 are in a positive position etc. When the contact 34 moves to a ne ative position, it is in a corresponding position with the contact 3'! until the relay 2 is energized moving its contacts to a positive position, at which time the contact 31 is in a corresponding position to contact 4!. Then relay 3 is energized to anegative position and contact M is in a position corresponding to contact it. Thus it is seen that since the message circuit is completed through contacts, assuming corresponding polar positions of two successive relays, that the circuit is only completed from the time of operation of the first relay until the operation of the second relay of two adjacent relays in the series. This prin ciple has been carried out in the selection of all message channels.

In the instance of the dispatchers message channel selecting relays the message wire is carried through contacts 28 and 3H assuming opposite polar positions, through the wire 232 to contact Hit. With the relays l to H inclusive, in the at rest period, the third contacts of each clay l to is inclusive are connected in series. With the relays l to it in a reverse position the fourth contacts of each relay are connected in series. The message wire which is connected to contact lei, of relay ll as heretofore explained, is mnuected to either third contact of relay it or the fourth contact of relay it according to r the position or" the contacts of relay ill. Now,

it will be easily seen that a circuit is set up, as soc-n the relays i? have responded to the long positive impulse, through positive contact iiil of relay ii, through negative contact 95 of relay l6, positive contact 96 of relay 15 in series to the contact 34 of relay i, so that as soon as relay I recei es its negative impulse and moves to a reverse position that a circuit is completed from the message wire through the contacts as explained through wire 238 to the signal lever i9. As the lever SL is in a central position no indication is sent over the message wire. Upon movement or" contact 31 of relay 2 to a positive position, the message channel for lever SL has been broken, and a message channel is set up through positive contact 31 of relay 2. As we have assumed that the lever SML is assuming right hand position, we have a message channel set up through a circuit heretofore traced. Thus the message channels are successively made and broken by the movement of each relay in the order that it occurs until the relay ll is again moved to a negative position which transfers the message circuit through the fourth-contact of each relay l to it. The fourth contact of each relay in the channel selecting group being in series, the message channels will be made and broken the same as shown heretofore for the third contacts of the relays, until the system has completed the cycle.

'Although the selection of message channels has been more specifically explained for the message channel selecting relays at the dispatchers ofiice, it is to be understood that the message channels at the way station as shown in Fig. 1C are selected and controlled in the same manner. Thus, all that'is necessary to have an indication sent from the dis'patchers ofiice to a given control relay such as relay SMR I is to have the relay at the way station connected to its corresponding control relay through contacts of the last and next operated channel selecting relay of both the dispatchers relay bank and the way station relay bank.

As the description of the message channel arrangement has progressed thus far, it is only necessary to state that as the system is normally at rest, except when messages are to be transmitted, there is a channel at each way station and at the dispatchers oflice, which is made during this at rest'period of time. This message channel is connected tosome means at the way station, which in the case of Fig. 1C, is relay 1N which will connect this message channel to the common wire Ztil, when an OS indication is to be transmitted from that way station. The message channel at the dispatchers omce which occursduring the at rest period, is connected to the relay IN in such a manner, that its ultimate connection to the common wire at the way station will result in the energization of relay IN. Thus means for initiation of the system from the way station is provided.

Modified form of way station In Fig. 2C, there is shown a modified organization of connections for the message channel selecting relays, which will give more message channels per number of relays used, than will the connections as shown in Fig. 1C. It will also be noted that the stepping line impulses are not shown as being repeated by a line relay, which is an optional requirement and does not effect the synchronous operation of the system on the assumption that the dispatchers channel selecting relays are controlled directly by the master relay MR. instead of by the line relay L".

In Fig. 2C, a combination bank of relays, composed of relays A, B, C and D and relays etc., through the third contacts of each relay.

, tively.

X, Y and Z, is so arranged in a circuit, as to make it necessary that thirty operations occur in this bank of relays, in a certain pre-determined sequence before this bank of relays has completed one cycle. This permits the closing of thirty message channels, which may be used for indication purposes. This combination bank of relays (Fig. 2C) is associated with an identical location on a railroad and with identical control relays, as are shown for Fig. 1C, being indicated by corresponding letters having suitable distinctive exponents.

The sequence of operation of this bank of relays is such, that the first long positive impulse picks up the relay 8T closing the front contact $69, which permits a portion of that long positive impulse to energize relay Z to a positive position, after which, the circuit arrangement permits the positive and negative impulses of the normal stepping rate to successively energize the relays A, B, C and D to their reverse dotted positions. Upon the movement of relay D to its positive position, the circuit arrangement is such that, the next succeeding impulse, which is negative, energizes the relay X to a negative position after which the relays A, B, C and D are successively operated to their normal position. Thus in like manner, at the completion of the successive operation of the relays A, B, C and D to either their reverse positions, or their normal positions, a relay in the group X, Y and Z, succeeding the last operated relay in that group, is operated to its opposite position, until the relays X, Y and Z have each been operated to their reverse positions and back to their normal positions, except the relay Z, which remains in its at rest position. The relay ST acts as a blocking relay to hinder the relay Z from responding to its impulse of normal order, and

. requires a long positive impulse to pick it up,

closing a contact so that relay Z may respond.

The operating contacts of the ABCD group of relays are the same as the group in the dispatchers office, so that, when negative and pos- 1 itive impulses are alternately placed on the wire 262, the relays A, B, C and D are operated to reverse positions and when positive and negative impulses are placed on the wire 264 the relays A, B, C and D are operated to normal positions. In each case, after the relays A, B, C and D have either completely reversed, or completely returned to normal, circuits are completed to the wires 263 and 254 respectively, which are then connected to the wires 262 and 264 respec- It is deemed, that this explanation will make it necessary to trace only the circuits in the group of relays X, Y and Z to the wires 262 and 254, stating that the A, B, C and D relays have operated, and again picking up the circuit at wires 263 and 255 respectively.

With the equipment at rest, the long positive impulse is impressed on the stepping wire through wire 242, the negative contact I52 of relay Z, wire 245, positive contact I4I, wire 253, negative contact I48, to the wire 284, through the contacts of relays A, B, C and D, wire 265, negative contact I44, wire 256, through the relay 8T to the common wire 204, thus picking up the relay 8T The front contact I69 is thus closed, completing a circuit through wire 259, and through the relay Z to the common wire 20$, energizing relay Z to a positive position.

With the relay Z in a positive position, the next four succeeding impulses flow from the stepping wire till, through wire 242, positive contact 152, wire negative contact I46, wire 249, positive contact 644, wire 262, to reverse the contacts of relays A, B, C and D by their respective impulses. Relays A, B, C and D being reversed, the circuit continues through the wire 263, positive contact 554, wire 244, positive contact I42, through relay X to the common wire 200, energizing the contacts of relay X with a negative impulse to a negative position.

With the relay X in a negative position, a circuit is completed from the stepping wire 2%, through wire 242, positive contact I52, wire 251, negative contact I46, negative contact I40, wire 243, negative contact I47, to the wire 264, thus returning the contacts of relays A, B, C and D to normal by their respective impulses. The circuit then continues through the Wire 265, negative contact I 44, wire 24?, negative contact I50 of relay Y, to the common wire 2%, thus operating the contacts of relay Y with a positive impulse to a positive position.

With the relay Y in a positive position, a circui't is completed from the stepping wire 20!, through wire 242, positive contact I52, wire 2527, positive contact 146, wire 258, positive contact N53, to the wire 262, to reverse the contacts of relays A, B, C and D by their respective impulses. The circuit then continues through wire 263, positive contact I54, wire 244, negative contact M2, wire 254, positive contact I55, through relay Z to the common wire 209, thus operating the contacts of relay Z with a negative impulse to a negative position.

With the relay Z in a negative position, a circuit is completed from the stepping wire 26!, through wire 242, negative contact I52, wire 245, negative contact MI, wire 264, thus returning the contacts of relays A, B, C and D to normal by their respective impulses. The circuit is then continued through the wire 265, negative contact I44, wire 241, positive contact I50, wire 248, negative contact Hi3, wire 262, through relay X to common wire 2%, thus operating the contacts of relay X with a positive impulse to a positive position.

With relay X in a positive position, a circuit is completed from the stepping wire 20 I, through wire 242, negative contact I52, wire 245, positive contact MI, wire 253, positive contact I48, to wire 262, to reverse the contacts of relaysA, B, C and D by their respective impulses. The circuit then continues through wire 263, negative contact I54, wire 25!, positive contact I49, wire 250, through relay Y to common wire 200, thus operating the contacts of relay Y with a negative impulse to a negative position.

Thus one cycle comprising thirty operations of the relays in this combination bank has been completed. Of these thirty operations the relays X, Y and Z have made six while the relays A, B, C and D have completed six times four namely twenty-four operations.

For the purpose of showing the thirty message channels obtainable with the combination of connections for the message channel selecting relays, as illustrated in Fig. 26, reference will be made to Fig. 3, in which the positions of the relays are represented by positive and negative signs arranged with three in the left column and four in the right as are the relays X, Y, Z and A, B, C, D, respectively, in Fig. 2C. In other words, a positive sign represents a contact in the right hand or positive position, and a negative sign represents a contact in the left hand or negative position, as heretofore explained. These symbolic representations of the positions of contacts, are so arranged that their position in respect to each other represent contacts on relays as shown in Fig. 2C, which have correspond- 5 ing positions in the drawings, for instance as followsz-positive sign 266 represents contact I45 in a positive position, negative sign 26! represents contact I5! in a negative position, positive sign 268 represents contact I56 in a positive position, positive sign 269 represents contact I59 in a positive position, negative sign 210 represents contact I62 in a negative position, positive sign 2' represents contact I65 in a positive position, and a negative sign 212 represents contact I68 in a negative position. Thus, the positive and negative signs as included under combination I (see Fig. 3) represent a set of contacts. on the relays A, B, C and D, and X, Y and Z, which will give one message channel when assuming this given combination of positions. In other words,

the contacts on said relays, which operate se-- quentially as heretofore described, are represented diagrammatically under the combinations I 2 3 4 etc. up to 30 such that each successive movement of relay contacts is represented in the diagram by successive combinations.

By way of illustration, the specific representation as shown by combination 8 of Fig. 3 is completely shown in diagrammatical form in Fig. 3A. In this drawing Fig. 3A, the relays and the contacts are given reference symbols to correspond with the drawing Fig. 20, having suitable exponents to distinguish them. However, in each case, the facts represented are identical, and may be enumerated, as fo-llows:--

(1) The 8 diagram means, that this combination is set up by the eighth movement of relay contacts in response to their respective impulses after the system has been initiated;

(2) The positive and negative signs represent the positions of the contacts after the relays have thus assumed the eighth combination of positions;

(3) The dotted line through the positive and negative signs represents the particular contacts which must be connected in series to constitute the message channel chosen for that particular combination. Each of the three enumerated facts is clearly set forth diagrammatically in Fig. 3A.

The symbolic showing in Fig. 3 serves peculiarly adaptable for describing and setting forth the thirty individual message channels that may be obtained by seven relays. As has been heretofore explained in connection with Fig. 1A and 1C, when a circuit is closed through two successive contacts in series, which are .assuming like positions, a circuit is closed but once during a complete cycle. This is also true of the message channels for the Way station shown in Fig. 2C,

if this rule of determining message channels is applied to both columns of relays used in Fig. 2C, it will be noted from Fig. 3 that in nearly every case the channel circuit (represented by a dotted line) includes successive like polarity signs in both columns, the reason why this is not necessary for all cases will presently be explained.

As there is but one movement of relay contacts in the XYZ group of relays as compared to the four movements of the ABCD group of relays,

then we may term these positions assumed by the XYZ group, the group characteristic, and the positions assumed by the ABCD group the indi vidual characteristic. Referring to Fig. 3, the groups of combinations have been designated by the letters XYZ having suitable exponents. It

is noted that the group characteristics or groups XYZ XYZ XYZ XYZ XYZ and XYZ are alternately two positive contacts and two negative contacts respectively which contacts are selected on successively operated relays, thus giving six distinctive group characteristics.

It is necessary in the dispatcher's message channel group of relays I to I 'I (see Fig. 1A) to have an odd number of relays, in order that the group could complete a cycle of operation. To meet a similar requirement, for the message channel selecting relays A, B, C and D, one relay from the group XYZ has been operated to complete the number of operations in each half cycle to an odd number.

In choosing the individual characteristic, two contacts which operate in succession are selected to be connected in series. However, it will be noted, that with the group characteristic contacts (relays X, Y and Z of Fig. 3) connected in series with the individual characteristic contacts (relays A, B, C and D), that a combination is obtainable so that the combination of the group characteristic is such, that its sign completes the number of signs for the individual characteristic to 5, thus making possible five combinations for each group characteristic. For this reason only contacts of three relays are required for certain message channels as clearly shown by the conventional showing in Fig. 3.

Let us consider more specifically the combination I5 which has a group characteristic of two positive contacts. A circuit is carried through these two positive group characteristic contacts (relays X, Y and Z) and through the last positive contact (contact of relay D) in the individual characteristic. This positive individual characteristic contact does not change when combination I5 is completed, however, the groupcharacteristic has changed to negative, thus breaking the temporarily closed message channel. Thus by using distinctive group characteristics, in combination with four distinctive individual characteristics, five distinctive combinations are obtainable for each group characteristic.

Although there are but thirty combinations obtainable with '7 relays, grouped as illustrated, it is to be understood that the total number of relays may be decreased or increased and operated on the same underlying principle, and that the number of combinations will be correspondingly changed, rendering the grouping adaptable for specific requirements.

It will be noted that the message channel shown in combination M3 is the message channel which is normally completed while the system is at rest, hence this message channel may be used for initiation purposes. Such a message channel is needed at each and every way station.

In embodying these principles for selecting message channels, in the present invention as shown in Fig. 20 the combination 30 (Fig. 3) is used for initiation purposes, and the combinations 2 3 G and 5 (Fig. 3) are used for message channels over which to control the relays SR SMR and DB and to give an OS indication from the track relay TR respectively.

The relay IN is so constructed that it has a slow releasing period, which is greater than the length of time that is required for the system to complete one cycle. Thus, as the relay TlR. changes its position the contact 2 I3 momentarily closes a circuit which energizes the relay IN as is obvious from the drawings. As the release period of the relay IN is greater than the length of time required for the operation of one cycle of the system, then it is always assured that the sys- 1 tem will complete at least one cycle after the relay TB has changed positions, thus the OS indication is insured of being indicated to the dispatcher, this on the assumption that the OS condition will persist for at least one time cycle.

With the system at rest, the message wire 252 is connected to common through a message channel as obtained in combination 35 when the contact i'lal is picked up due to momentary energization of relay 1N This initiation message circuit for the dispatchers ofiice has been heretofore described, so that the initiation circuit at the way station as shown in Fig. 2C need only be traced from the message Wire as follows:from message wire 282, through wire 255, negative contact 555, wire'252, negative contact I5I, wire 2T4, negative contac 533', wire 2 55, front contact I'll}, to the common wire 2%, thus initiating the system. The OS indication, or indication of change of the position of the track relay TR is now ready to be transmitted over the combination as set up in Fig. 3, namely combination 5 After the message channel selecting relays have been stepped along in synchronism, with the message channel selecting relays at the dispatchers oiiice, until this fifth channel is set up, then the following circuit is completed for the OS indication:negative battery from battery 2'55, back contact I31, wire 21?, positive contact I68, wire 278, positive contact I45, wire 245, positive contact 956, wire 255, through the message wire 292 to the dispatchers office, through positive contact 28, wire 231, negative contact Si, wire 232, positive contact llli, negative contact 5, positive contact 95, negative contact 85, positive contact 8i, negative contact Tl, positive contact negative contact 59, positive contact 65, negative contact 5!, positive contact 5'7, negative contact 53, positive contact 45, positive contact 45, through the OS relay to the common wire 205. Thus contact E is energized to a negative position illuminating the indicating lamp I.

Let us again assume the system to be at rest, and that the dispatcher wishes to reverse the switch TSW so that the east bound trafiic may be routed into the passing siding of PS To accomplish this result the dispatcher moves the lever SML to a left hand position, which initiates the system and steps the message channel selecting relays in the way station as shown in Fig. 2C, in synchronism with the message channel selecting relays in the dispatchers ofiice, in a manner heretofore described, until the third message channel is set up, at which time a control impulse is sent to the relay SMR This control impulse flows through a circuit in the dispatchers ofilce as heretofore described, to the way station over the wire 262, to the relay SlVlR through a oil nit traced as follows:-from the message Wire 252, through the wire 255, positive contact [55 of relay Z, wire 24-6, positive contact I45, of relay X, wire 2H3, negative contact I58 of relay D, positive contact I65, positive contact 552, wire 28 3, through the relay SMR to the common wire Elli]. Thus the polar contact of the relay SMR is energized to a negative position, which in turn controls switch machine SM thus moving the switch TSW to a reverse position. The system continues stepping until two cycles of the message channel selecting groups of relays has been completed in a manner as heretofore described.

Now let us consider that the dispatcher wishes to clear the signal SE To accomplish this, the

dispatcher moves the lever SL to a right hand position, which initiates the system and steps the message channel relays in the dispatchers ofiice along in synchronism with the message channel relays at the Way station as shown in Fig. 20, in a manner as heretofore described. When the message channel selecting relays have been stepped along until the second message channel is set up, a positive impulse is sent over the mes sage wire 202 from the dispatchers oifice the way station shown in Fig. 20 in a manner hereto fore described and which passes through a circuit in the way station as shown in Fig. 20, being traced as follows:from the message wire 202, through wire 255, positive contact I56 of relay Z, wire 246, positive contact I45 of relay X, wire 278, negative contact I68, relay D, positive contact I65 of relay C, negative contact I62, of relay B, negative contact I59 of relay A, wire 285, through the relay SR to the common wire 2%. Thus the signal relay SR is energized with positive potential. When the message channel relays have been stepped along until the fourth message channel has been set up, a circuit is completed in the dispatchers office which places a positive impulse upon the stepping wire 252 as heretofore explained which in turn is placed upon the relay DB at the way station shown in Fig. 20 through a circuit traced as follows:-from the message wire 202, through wire 255, positive contact I56 of relay Z, wire 246, positive contact I45 of relay X, wire 278, negative contact I68 of relay D, negative contact I65 of relay C, wire 283, through the relay DR to the common wire 25!]. Thus the relay DH is energized with positive potential, which causes its polar contact to move to a positive position. With the polar contacts of relays SR and DR in a positive position the signal SE is cleared, allowing east bound traific to proceed over the reversed switch TSW onto the passing siding PS The message channel selecting relays step along until they have completed twocycles.

Having thus shown, and described, several specific embodiments of a rather involved and comprehensive system, for carrying out certain functions, it is desired to be understood that the particular arrangement of devices and circuits illustrated need not be adhered to, but that many changes, modifications and additions may be made, in the individual devices as well as their co-ordination with each other, without departing from the scope or spirit of the invention as demanded by the scope of the appended claims.

What we claim is:

1. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track and each controlled by traffic conditions ahead, of means for controlling said signals distinctively over the same line wires comprising, a bank of relays in the dispatchers ofl'ice, a bank of relays at each of'a plurality of way stations, means for operating the relays of each bank sequentially in a particular order, and over an uninterrupted line circuit, in such a way that corresponding relays of all the banks are operated synchronously and sothat corresponding relays of all banks at all times assume corresponding positions, and a plurality of message circuits for controlling said signals closed sequentially and each including the same line wire and including contacts of corresponding relays of the dispatchers oiiice bank and a particular way station bank.

2. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals each controlled by trafiic conditions ahead located along the railway track, of means for controlling said signals distinctively over the same line wires comprising, a bank of relays in the dispatchers ofiice, a bank of relays at a particular way station, means for operating the relays of each bank sequentially in a particular order in such a way that corre sponding relays of both banks are operated synchronously and so that corresponding relays cf the two banks at all times assume corresponding positions, and a plurality of message circuits for controlling said signals subject to traliic conditions ahead closed sequentially and each includ ing the same line wire and including contacts of corresponding relays of the dispatchers oflice bank and a particular way station bank.

3. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctively over the same line wires comprising, a bank of stepping and channel selecting relays in the dispatchers office, a bank of channel selecting relays at a particular way station, normally inactive stepping means for operating the relays of each bank sequentially in a particular order in such a way that corresponding relays of both banks are operated synchronously and so that corresponding relays of the two banks at all times assume corresponding positions, means for rendering said stepping means active to operate said channel selecting relays through a specific plural number of cycles of operation, and a plurality of message circuits for controlling said signals closed sequentially and each including the same line wire and including contacts of corresponding relays of the dispatchers ofifice bank and said way station bank.

4. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctively over the same line wires comprising, a bank of channel selecting relays in the dispatchers ofiice, a bank of channel selecting relays at each of a plurality of way stations, nor-' mally inactive stepping means including an uninterrupted wire running from the oflice to each Way-station for operating the relays of each bank sequentially in a particular order in such a way that corresponding relays of all banks are operated synchronously and so that corresponding relays of all banks at all times assume corresponding positions, means controllable from any way station and from said dispatchers office for rendering said stepping means active to operate said channel selecting relays through a specific number of cycles of operation, and a plurality of message circuits for controlling said signals closed sequentially and each including the same line wire and including contacts of corresponding relays of the dispatchers ofiice bank and a particular way station bank.

5. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctively over but two line wires and a common wire comprising, a bank of channel selecting relays in the dispatchers ofiice, a bank of channel selecting relays at each of a plurality of way stations, normally inactive stepping means for operating the relays of each bank sequentially in a particular order in such a way that corresponding relays of all banks are operated synchronously and so that corresponding relays of all banks at all times assume corresponding positions, means for rendering said stepping means active to operate said channel selecting relays through a specific plural number of cycles of operation, a plurality of message circuits for transmitting OS indications and controlling signals each including the same line wire and including contacts of corresponding relays of the dispatchers ofiice bank and a particular way station bank.

6. In a train, dispatching system of the wayside signalcontrol type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctively over only two line wires and a common wire comprising, a bank of channel selecting relays in the dispatchers oflice, a bank of channel selecting relays at each of a plurality of way stations, normally inactive stepping means for operating the relays at each bank sequentially in a particular order in such a way that corresponding relays of all banks are operated synchronously and so that corresponding relays of all banks at all times assume corresponding positions, means controllable from any way station and from said dispatchers ofiice for rendering said stepping means active to operate said channel selecting relays through a specific plural number of cycles of operation, a plurality of message circuits for transmitting OS indications and controlling signals each including the same line wire and including contacts of corresponding relays of the dispatchers ofiice bank and a particular way station bank.

7. The method of controlling any one of a plurality of distant wayside signals of a railway distinctively over the same line wire, which consists in a chain of relays at a dispatchers ofiice and another chain of relays at a distant way station, in causing the relays of the two chains to be operated sequentially in synchronism so that corresponding relays of the two chains assume corresponding positions at all times and in operating said relays through complete cycles when operating, and in controlling said signals subject to trafiic conditions in advance thereof distinctively and separately over the same line wire and corresponding contacts of corresponding relays of the two relay chains.

8. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctively over the same line wires comprising, a bank of relays at a dispatchers office, a bank of relays at a distant way station, stepping means for operating the relays of both banks sequentially in a particular order in synchronism and in such a way that corresponding relays of both relay banks assume corresponding positions at. 'all times and operate until the cycle of operation is completed at which point said stepping means is locked up, a slow-acting relay for unlocking 'said stepping means and a plurality of message circuits for controlling said signals closed sequentially and each including the same line wire and including contacts of corresponding relays of the dispatchers ofiice bank and the way station bank.

9. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctively over the same line wires comprising, a bank of relays at a dispatchers ofiice, a bank of relays at a distant way station, stepping means for operating the relays of both banks sequentially in a particular order in synchronism and in such a way that corresponding relays of both relay banks assume corresponding positions at all times and operate until the cycle of operation is completed at which point said stepping means is locked up, synchronizing means for normally and automatically bringing saidrelays in step and restarting said stepping means once after each initiation of the system, whereby,said system opcrates through at least two cycles of operation for each initiation, and a plurality of message circuits for controlling said signals closed sequentially and each including the same wire and including contacts of corresponding relays of the dispatchers ofiice bank and the way station bank.

10. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctively over the same line wires comprising, a bank of relays at a dispatchers oflice, a bank of relays at a distant way station, stepping means for operating the relays of both banks sequentially in a particular order in synchronism and in such a way that corresponding relays of both banks assume corresponding positions at all times and operate until the cycle of operation is completed at which point said stepping means is locked up, synchronizing means including a slow acting relay for bringing said relays in step and restarting said stepping means, a plurality of message circuits for controlling said signals closed sequentially and each including the same line wire and including contacts of corresponding relays of the dispatchers ofiice bank and the way station bank, and means for energizing said slow-acting relay and initiating operation of said stepping means.

11. In a train dispatching system of the wayside signal control type, the combination with a large number of wayside signals located along the railway track, of means for controlling said signals distinctly over the same line wires comprising, a bank of relays at a dispatchers office, a bank of relays at a distant way station, stepping means for operating the relays of both banks sequentially in a particular order in synchronism and in such a way that certain relays of both relay banks assume certain positions at certain non-recurring times and the relays of the banks operate until the cycle of operation is completed at which point said stepping means is locked up, a slow-acting relay for unlocking said stepping means, and a plurality of message circuits for controlling said signals closed sequentially and each including the same line wire and including contacts of corresponding relays of the dispatchers office bank and the way station bank another slow-acting relay which so long as it assumes its de-energized condition while having its winding energized applies current to said first mentioned slow-acting relay, and a contact on another slow-acting relay for controlling the re-energization of said first mentioned slow-acting relay at the end of the subsequent cycle of operation of said relay banks.

12. In a centralized traffic controlling system for railroads; a distant track switch; a switch machine for operating said track switch; and means for controlling said switch machine from a central office comprising; a series of relays in said central office, a corresponding series of relays at said distant track switch, one line relay only associated with each of said series of *elays, a line circuit extending between said central office and said distant track switch for connecting said line relays in a series circuit uninterruptible except at said central oifice, means for controlling the energization of said line circuit only from said central ofiice, circuits for interconnecting each of said series of relays with its respective one line relay to cause the relays of each series to be sequentially energized upon successive energize,- tions of its one line relay, thereby causing corresponding relays of the two series of relays to be energized simultaneously when said line circuit is energized, and a message circuit for controlling said switch machine available when a particular pair of said corresponding relays of said two series of relays is energized.

13. In a centralized trafiic controlling system for railroads; a distant track switch; switch machine for operating said track switch; and means for controlling said switch machine from a central office comprising; a series of relays in said central oifice, a corresponding series of relays at said distant track switch, one line relay only associated with each of said series of relays, a line circuit extending between said central office and said distant track switch for connecting said line relays in a series circuit uninterruptible except at said central ofiice, means for controlling the energization of said line circuit only from said central ofiice, circuits for interconnecting each of said series of relays with its respective one line relay to cause the relays of each series to be sequentially energized upon. successive energizations of its one line relay, thereby causing corresponding relays of the two series of relays to be energized simultaneously, a slow acting relay associated with each of said series of relays which prevents the initiation of operation of said series unless said slow acting relay is first operated, means for controlling said slow acting relay, and a message circuit including but one additional line wire for controlling said switch machine rendered available for controlling said switch machine when a particular pair of corresponding relays of said two series of relays is energized.

14. In a centralized trafiic controlling system for railroads; a distant track switch; a switch machine for operating said track switch; and means for controlling said switch machine from a central oilice comprising; a series of polar relays of the two position type at the central ofiice, a corresponding series of polar relays of the two position type at said distant track switch, means for successively operating the corresponding pairs of relays of said two series of relays from their normal to their reverse position during the first half cycle of operation and operating successively corresponding pairs of relays back to their normal position during the second half of the cycle of operation, the relays of each pair being operated simultaneously, and a distinct message circuit connecting said central office and said track switch completed upon each operation of a pair of relays, whereby there are rendered available two message circuits for each relay of a series during each cycle of operation of said system.

15. In a centralized traflic controlling system for railroads; a distant track switch; a switch machine for operating said track switch; and means for controlling said switch machine from a central oflice comprising; a series of polar relays of the two position type at the central oifice, a corresponding series of polar relays of the two position type at said distant track switch, means for successively operating the corresponding pairs of relays of said two series of relays from their normal to their reverse position during the first half cycle of operation and operating successively corresponding pairs of relays back to their normal position during the second half of the cycle of operation, the relays of each pair being operated simultaneously, and a plurality of message circuits in number equal to twice the number of relays in each series, each message circuit of which includes the contacts of two adjacent relays, closed sequentially during operation of said relays, and means for controlling said switch machine over one of said message circuits.

16. An impulse counting group of relays comprising, a series of two position polar counting relays of the first order, a series of two position polar counting relays of the second order, and interconnecting circuits to efiect repeat operation through the series of relays of the first order for each operation of one of said relays of the second order, whereby the total number of impulses which may be absorbed by said counting group of relays is equal to twice the product of the counting relays of the first order and the number of counting relays plus one of the second order.

17. For use in a centralized trafiic controlling system for railways, a bank of polar relays of the two-position stick type, means for successively operating the relays each to its opposite position, and then each back to its first position by energizing a circuit with energy of alternating polarities.

18. For use in centralized traffic controlling systems for railways, in combination, a chain of two-position polar stick type relays, an energizing circuit for the first relay of the chain including its own point of one polarity, each succeeding relay having an energizing circuit including its own point of one polarity, the point of the next preceding relay of the same polarity, and points of alternate polarities, respectively, of the remaining preceding relays.

19. For use in centralized traific controlling systems for railways, in combination, a chain of two-position polar stick type relays, an energizing circuit for the first relay of the chain including its own point of one polarity, each succeeding relay having an energizing circuit including its own point of one polarity, the point of the next preceding relay of the same polarity, and points of alternate polarities, respectively, of the remaining preceding relays, a second energizing circuit for each relay relatively arranged as above, but the case of each relay, relating to the point of such relay of opposite polarity to that recited above.

20. In a control means of the selector type; a bank of selecting relays; means for subjecting said bank of relays to a series of spaced current impulses; and an energizing circuit for each relay, the energizing circuit for each relay being completed only upon the operation of a preceding relay but being efiective to cause the operation of its relay only upon the reception of the next impulse of said series of impulses following that impulse which caused the operation of the preceding relay, and the operation of each relay making its energizing circuit immune to subsequent current impulses, whereby each relay responds only to its respective impulse in said series of impulses.

2.1. In a control means of the selector type; a bank of selecting relays; means for subjecting said bank of relays to a series of spaced current impulses; an energizing circuit for each relay of the bank, the energizing circuit for each relay being completed only upon the operation of a preceding relay but being effective to cause the operation of its relay only upon the reception of the next impulse of said series of impulses following that impulse which caused the operation of the preceding relay, and the operation of each relay making its energizing circuit immune to subsequent current impulses, whereby each current impulse causes operation of but one of the relays of the bank of relays, and whereby the relays are operated in succession; and channel circuits sequentially closed by said bank of relays.

22. In a control means of the selector type, in combination, a bank of selecting relays, an energizing circuit for each relay, means for subjecting the bank to a series of spaced current impulses, the energizing circuit for each relay being completed only after the immediately preceding relay has been operated, and the operation of each relay making its energizing circuit immune to subsequent current impulses, whereby each current impulse causes operation of but one of the relays of the bank of relays, and the relays are operated in succession, another energizing circuit for each relay of the bank, each relay being a twoposition relay, said another circuits being related to each other as are the first said energizing circuits, but related, in each case, to the other position of the relay than the position to which the first said energizing circuits are related.

23. In combination, a first line wire connecting an office and a station, a movable device at said station, means operating in response to a change in the position of said device to deliver a starting impulse to said first line wire, a second line wire connecting said ofiice and station, a bank of stepping relays in said ofilce responsive to said starting impulse for delivering another impulse to said second line wire, means at the station responsive to said other impulse to deliver to said first line wire an indication impulse under the control of said device, and means at the ofiice selectively controlled by said indication impulse.

24. In a centralized trafiic control system for railroads, a control oi'fice, a plurality of way stations, a stepping circuit, automatic impulsing means for placing impulses on said stepping cir cuit, step-by-step means at each of said stations and said control office all operated in synchronism by the application of said impulses to said stepping circuit, trafiic controlling devices at each way station, and a starting circuit extending between said control ofiice and said way stations capable of being closed at each station when a change in the position or condition of one or more of said traffic controlling devices occurs at a station if said automatic impulsing means is not in operation.

FOREST B. I-IITCI-ICOCK. OSCAR H. DICKE.

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