US2149222A - Centralized traffic controlling system for railroads - Google Patents

Description

A. LANGDON 2,149,222

ROLLlNG SYSTEM FOR RAILROADS "Feb. 28, 1939.

GENTRALIZED TRAFFIC CONT Filed Aug. 15, 1934 5 Sheets-Sheet l INVENTOR M ATTORNEY A. LANGDON Feb. 28, 1939.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS 1934 5 Sheets-Sheet 2 Fil ed Aug. 15

INVENTOR 41110, W

ATTORNEY A. LANGDON Feb. 28, 1939.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS I Filed Aug. 15, 1934 5 Sheets-Sheet 3 INVI'EN TOR 4. a!

BY M 74;, ATlN Y .flll mm Tu Feb. 28, 1939. A. LANGDON CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Aug. 15, 1934 5 Sheets-Sheet 4 44% ATTQRNE I I INVENTOR BY 4oz ook Feb. 28,1939. LANGDON I I 2,149,222

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS FiledAug. 15, 1954 5 Sheets-Sheet 5 INVENTOR A/WTKOZRINEY v Patented F eb. 28, 1939 UNITED STATES PATENT OFFICE Andrew Langdon, Brighton, N. Y., assignor to General Railway Signal Company, Rochester,

Application August 15,

20 Claims.

This invention relates to centralized traflic controlling systems for railroads, and more particularly pertains to a system for the interrelation of signals and switches in interlocking plants.

Itoften happens in interlocking plants that a group of switches and signals are spaced adistance from another group of switches and signals with intervening or interconnecting track sections; The switches and signals in any one group maybe interlocked and interrelated in accordance with any one of several types of interlocking. However, to provide for the passage of traffic from one interlocked group to the other, it becomes necessary to provide an interrelationship between the two interlocked groups of switches and signals. a I

The present invention proposes to provide means for the interrelation of two or more interlockedgroups both where such groups are adjacent each other and where such groups are separated by an appreciable distance. For those groups separated by an appreciable distance, the present invention provides a traffic lever or button for each such trafilc section, which traflic lever must be operated to a position corresponding to the direction of traflic set up for that trafiic section. Such a traffic lever is constructed to remain in its last operated position so as to advise the operator of the potential direction of traflic for each such traffic section.

In other words, a systemis contemplated wherein the operator can supervise the positioning of railroad track switches and the clearing of signals to govern traffic over various routes through an interlocking plant together with means associated with each traffic section of'track connecting the route determining points, which means must be operated in order to establish movement of trafiic into such a section, and which means also .refleets the previous direction of travel in such section.

Such directional traffic governing levers are provided in such a manner that the accidental reversal of alever of this character does not efiect a route already established and having its governing signal cleared, that is, once a signal is cleared for a particular route, the only way that route can be changed-is by the return to stop of the lever governing such signal for that route.

Another characteristic feature of the present inventionresides in the arrangement of the traffic direction control for each section in such a manner that the clearing 'of a signal 'for the entran'ceof a train into such section prevents'the reversal of traflic direction in that section, but

1934, Serial No. 739,977

the clearing of a signal for the leaving of a train from such traffic section does not prevent the reversal of traflic direction in the section providing the previously mentioned entering signal has been put to stop.

Further objects of the invention are to accomplish the above and other purposes in a safe and reliable manner to meet the requirements of railway signalling practice.

Other objects, purposes and characteristic features of the present invention will be in part 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 like reference characters designate corresponding parts throughout the several views, and in which:

Fig. 1 illustrates in a conventional manner an interlocking system arranged in accordance with the present invention for such situations as require no 'trailic direction lever for facility in operation because of the short section between two interlocked groups.

Figs. 2A and 23, when placed end to end, constitute an interlocking system arranged in accordance with the present invention, as applied to two interlocked groups Where there is an appreciable intervening section and where a directional control lever for such intervening section is highly desirable, as hereinafter more specifically pointed out Figs. 3A and 3B illustrate a modified form of Fig. 1 to illustrate the manner in which the two interlocked groups illustrated are arranged when they are associated with one or more other interlocked groups; and

Fig. 4 illustrates in a conventional manner a modified form of Figs. 2A and 2B in which the reversal of trafilc in an intervening section between two interlocked groups is positively prevented so long as that section is occupied by a train.

For the purpose of simplifying the illustration and facilitating in the explanation thereof, the various parts and circuits constituting the embodiment of the invention have been shown diagammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy to understand the principles and ,mode of operation, than with theid-ea of illustrating the specificconstruction and arrangement of parts that wouldbe employed in practice.

the negative designated by The various relays and their contacts are illustrated in a conventional manner, and symbols are employed to indicate terminals of batteries or other suitable source of electric current instead of showing all of the wiring connections to these terminals,

The symbols and are used to indicate the positive and negative terminals respectively of suitable batteries or other sources of electrical energy; and those circuits with which these symbols are used are presumed to have current flowing from the positive terminal designated by to The symbols (B+) and (B) indicate connections to the opopposite terminals of a suitable battery or other direct current source which has a central or intermediate tap designated (CN) and the circuits with which these symbols are used, may have current flowing in one direction or the other depending upon the particular terminal used in combination with the intermediate tap (CN). The symbol (CN) may at times be employed to replace the illustration of a common Wire. If alternating current is employed to replace the direct current sources illustrated by these symbols, then these symbols may be used to indicate or represent the instantaneous relative polarities of the alternating current sources thus employed.

In the accompanying drawings, the invention has been shown applied to simple track layouts including a stretch of track having track switches connecting diverging routes thereto; but it should be understood that the invention is not limited, as thus shown, to the control of switches and signals of such a simple layout, but may be extended for any desired number of switches and signals and may be readily applied to all types of track layouts commonly found in interlocking plants.

APPARATUS The track layout of Fig. 1 includes a stretch of track, which for convenience in describing the present invention, is divided into five track sections, namely, track sections ll, [2, l3, l4 and I5. The track section I2 is shown as including a suitable railroad track switch IZTS which serves to connect a turnout track section Hi to the main track; and similarly, the track section l4 includes a suitable railroad track switch HTS which serves to connect another turnout track section I! to the main track.

The track switches HTS and MTS are preferably operated by suitable switch machines (not shown) to normal and reverse positions, which switch machines may be of any suitable type, such for example as disclosed in the patent to W. K. I-Iowe Pat. No. 1,466,903 dated September 4, 1923, and which switch machines are remotely controlled by the operator located in a central tower through suitable control circuits such as shown for example in the application of S. N. Wight Ser. No. 689,109, filed Sept. 12, 1933, corresponding to British Patent No. 440,048, dated December 12, 1935. The control circuits for these track switches have not been illustrated in the drawings, because it is believed that the present invention may be best understood by a description of a simple disclosure which does not include the details of the switch control.

Although various signal arrangements might be provided for the track layout chosen for the embodiment shown in Fig. 1, the signal I is illustrated as governing east bound traffic over the main track up to the signal 2, which signal 2 governs east bound trafiic over the main track up to the next succeeding east bound signal (not shown). Signals I and 2 also govern traific over the diverging routes formed by the track switches IZTS and HTS respectively. Signal 5 is provided for governing west bound trafiic over the main track to the signal 3, which in turn governs west bound trafiic up to the next succeeding west bound signal (not shown). For the purpose of governing traffic from the diverging track section l6 onto the main track, the signal 4 is associated with the track switch IZTS; while the signal 6 is associated with the track switch MTS for the purpose of governing traflic onto the main track from the track section El. These signals are illustrated as being of the color light signal type, but may be of any other type, or any other suitable signalling means, governed in accordance with the present invention by signal levers located in the central oflice or tower.

In actual practice, some of the signalling relays, devices and the like, may be located in suitable sub-towers along the track way, while cer tain other devices including the control levers may be located in the operators central oiiice or tower; but for convenience in describing the present invention, it is assumed that the control levers for the signals and their various associated circuits and relays are located in the central tower, and that suitable control circuits are provided for remotely connecting the central tower with the trafiic controlling devices in the field. It is of course to be understood that any suitable disposition of the apparatus may be made without affecting the system of the present invention in its operation and usefulness.

In the central office, a suitable control machine is provided upon which the switch and signal control levers together with the trafiic control levers are mounted in convenient positions adjacent or upon a miniature track diagram corresponding in every respect to the actual track layout in the field. Also, suitable indications would be employed in practice to indicate to the operator the position of the switches, the condition of the signals, and the occupied or unoccupied condition of the track sections, but for convenience in describing the present invention neither the relative position of the control levers nor the indications of the traffic controlling devices are illustrated.

The signal control levers ISL, 45L, 3SL, ESL, ESL and ESL are employed for governing the signals I, 4, 3, 2, 5 and 6 respectively (see Fig. 1).

As above mentioned, the condition of occupancy of the various track sections is preferably repeated in the tower by track relays or track repeating relays, but for convenience in describing the invention applied to the track layout of Fig. 1, such means. has been omitted from the drawings. Such track sections into which the track is divided by suitable insulated joints are assumed to have track circuits of the usual closed circuit type.

The position of the track switches is indicated in the tower by suitable switch repeating relays indicated by the letter reference characters WP and associated with the particular track switch as indicated by the preceding numerals. Each of these switch repeating relays WP is of the polar neutral type, and is energized with current of a particular polarity depending upon the particular position of its corresponding track switch and its locked condition, and whenever a switch is unlocked, the corresponding repeating relay WP is deenergized.

switches. effective only when a train is approaching the in applying the prese'rit invention -to asystem 'niployin gswitch control with ap roach and detector looking, it may be desirable to provide repeating relays associated with the relays WP, which i'n'dica'te the correspondence 'of the switch control means with the track switch, and the contacts of which maybesubstituted in the circuits of the *present disclosure inplace of the contacts of t'he' re1a'.ys WP, allof which has been more specically disclosed in the pending appli- 'catien'of S. N. Wight Ser. No. 689,109 filed Sep- '-tembr '12, 1933, corresponding to British Patent No, "qr-40,048, dated "December 12, 1935, and in the 'UJS. Patent to S. N. Wight, Patent No. 2,0271569 dated January 14, 1936.

- Levers repeating relays P are associated with their respective signal control levers SL, as indicated by their preceding numerals. Likewise,

route relays RR are associated with their respective signal levers SL, 'as indicated by their preceding numerals. These route relays RR indicate whether aparticular route is established over the actual track layout by reason of their energization over a route circuit corresponding to the track layout.

Relays'G are associated with their respective signals, as designated by the numerals precedingtheir letter reference characters. Each of theserelays, when deenergized, causes its associated signal to-indicate stop; but, when energized, causes its associated signal to indicate proceed subject to traffic conditions in accordance with the usual practice.

A time-element thermal relay ITR is illustrated as associated with the signal I; and similarly, a time element thermal relay 5TB is illustrated as associated with the signal 5. Each -'of these thermal relays has associated therewith a stick relay S, as designated by their preceding numerals, which stick relays are controlled by their respective thermal relays TR and signal relays G in a joint manner explained hereinafter. -It is noted in thisconnection, that in practice'wherethere is a large layout and other and 3B later considered). These thermal time element relays TR are associated with their respective signals in a manner for delaying the operation of their respective track switches a predetermined time after the putting to stop of such signals governing trafilc over the track Also, such delay period may be made signal; althoughthis is not-shown in the drawings. These thermal relays are also used in accordancewith the present invention, as illustrated in the present disclosure, for controlling the reversal of traffic direction The control of the track switches by the stick relaysS is sometimes accomplished through the "medium of directional stick tumble down relays to'provide for the rear releasing of the track 'switchesin a'route, all of which may be employed without departing from the present in- 'vention.

"(Figs 2A-a'nd 2B.) The structureand arrange- "m'ent'disclosed in'Figs. 2A and-2B is very similar to that provided in Fig. 1, but has been arand where it is desirable toprovide a directional "more readily apparent hereafter.

control lever to govern traflic in such intervening section.

The track layout includes sections 20, 2|, 22, -23, 24 and Him the main track. The track switch HTS connects a diverging track section 26 to the main track; and similarly, a track switch 24TS connects "a diverging track section 21 to the main track.

Signal -3IA provides for the control of east bound traflic "over the main track up to the signal 321A; while the signal 3|B controls the traffic for the-diverging route onto section 26. Likewise, signal 32A governs traffic over themain track; while thesignal 323 controls east bound traffic onto the diverg'in'g track section 21. The signals 36A and '33A control west bound trafiic on the main track; 'while the signals and 35 control trafiic 'ofi'the respective-diverging tracks. The "main track signals 'have'been provided with call-onsignals ENG, 36C, 32C and 33C respectively. The call-on'signalaasfor example 3IC, control trafi'ic over either the main track or the diverging route, and have the significance, when cleared, that a'trainm'ay proceedprepared to stop on sight of an obstruction. It is to be understood that the main signals, as for example 3IA and 31B, indicate that the section in advance isnot occupied and that it is safe for traflic to proceed in the usualmanner. The call-on type of sign-a1 is a necessary adjunct of an interlocking system of the type contemplated in accordance with the present invention in order to provide for certainnecessaryswitching operations.

Itis assumed that the track switches-'2 ITS and 24TS are operated by suitable power switch machines and controlled in a similar manner as mentioned in connection with the track switches of Fig. '1.

Each track switch has associated therewith a suitable switch repeating relay illustrated as relays 2IWP and MWP, which relays may have substituted therefor'in the circuits of the disclosure suitable correspondence relays as mentioned in connection with Fig. 1; but for an understanding of the present invention it is unnecessary to consider such features of the contemplated system.

The track section 2| is illustrated as having a track circuit with the usual track battery and track relay HT, and similarly the track sections 22, 23 and 24 are indicated as having. track relays 22T,'23T and 24T- respectively. The remaining sections are preferably provided with track relays also, which relays have not been considered as necessary to the present disclosure.

Each signalis provided with a signal control lever SL, a signal control lever repeating relay P, a signal relay G, and a'route relay RR, each of which letter reference characters is provided with a suitable preceding numeral to indicate with which signal'it is associated. The signal control relays G are subject to the control of the relays P and RR for determining when a route has been established,-and may also be controlled in accordance with trafiic conditions, although only certain of. these relays have been illustrated as thus controlled. Thermal relays TR and stick relays S are associated with certain signals for reasons similar to those pointed out in connection with Fig. 1.

Directional-- stick relays ZIES and 2'lWShave beenillustrated as associated with the track switches ZITS and 24TS respectively for reasons However, it

is to be understood in this connection that suitable relays ZIWS and MES would also be associated with the respective track switches in actual practice. These directional stick tumble down relays WS and ES control the lock relays for the respective track switches and provide for the rear releasing of the switches in a route as a train passes through.

Relays I-ID are controlled in accordance with trafiic conditions in advance of the signals with which they are associated and provide for the automatic control of such signals in the usual manner.

For the purpose of providing directional control over the track sections 22 and 23, a directional control lever DR, which in practice is associated on the miniature track diagram with the corresponding miniature track sections 22 and 23, is provided to control directional relays EF and WE. These directional relays EF and WP are of the polarized type having polar armatures which are actuated to opposite positions upon the application of opposite polarities, which armatures remain in their last actuated positions irrespective of subsequent deenergization. Such retaining means may be of the magnetic stick type or of the mechanical stick type, the particular means employed to accomplish the stick feature being immaterial.

The directional relays EF and WF provide for the control of the HD relays for opposing signals 3! and 33 over only two line wires. Such control of the HD relays also provides for checking whether these two separated directional relays are in corresponding polar positions, all of which will be pointed out more specifically hereinafter.

It is believed that the characteristic features and purposes of the present invention will be best understood by giving the remaining description from the standpoint of typical operations.

OPERATION (FIG. 1) Normal conditions Although track switches are usually left in their last operated positions, the track switches IZTS and MTS have been shown as being in their normal positions and are presumed to be in correspondence with the respective switch machine control levers (not shown. The signal control levers, however, are usually returned to normal at stop positions, as shown, so that the respective signals are displaying stop indications.

More specifically, the red lamp of signal I is energized through back contact 45 of relay IG; the red lamp of signal 3 is energized through back contact 54 of relay 3G; the red lamp of signal 4 is energized through back contact 55 of relay 4G; the red lamp of signal 2 is energized through back contact ll of relay 2G; the red lamp of signal 5 is energized through back contact 88 of relay 5G; and the red lamp of signal 6 is energized through back contact 82 of relay 6G.

With the track sections unoccupied, the track relays are normally energized, but as automatic track circuit control is not provided in connection with the directional features characteristic of the present invention in Fig. 1, such relays have not been illustrated.

The switch repeating relays WP are energized in accordance with the normal positions of their track switches, as above mentioned, thus causing the circuits with which they are associated to be selected in accordance with the normal positions of the track switches.

With the signal control levers in their at stop positions, the time element stick relays S are energized through their respective stick circuits, as presently to be set forth. The pick-up of these relays S is accomplished either by the elapse of a time measured by their respective thermal relays TR, as described later, or by other types of releasing means (not shown) commonly used in approach and detector locking when the time period measured by the thermal relays is not required.

The relay IS is maintained picked up by a stick circuit closed from through a circuit including back contact 94 of relay IG, heating element of relay l TR, front contact 6! of relay IS, windings of relay IS, to The current, which flows in this circuit to maintain the relay IS energized, is insufficient to actuate the thermal element of the relay ITR.

Signal control Consideration will now be given to the individual control of the signals by their respective levers subject to route control, directional looking and time releasing of such locking, which features will be described hereinafter.

For example, assuming the system to be in normal conditions, as illustrated, the actuation of the signal lever ISL to its dotted line position causes the relay IP to be energized by a circuit closed from through a circuit including the lever ISL in its dotted line position, windings of relay IP, back contact 4| of relay IRR, to A response of the relay IP to such energization completes its stick circuit including front contact 42, thereby rendering the relay IP wholly dependent upon the lever ISL, if the route relay IRR is picked up in response to the energization of relay IP provided the route is established and proper to be cleared, as will be subsequently described.

The relay IG is then energized with IRR picked up by reason of a circuit closed from through a circuit including front contact 43 of relay IRR, front contact 44 of relay IP, windings of relay IG, to Such energization of the relay lG opens the stick circuit for the relay IS at back contact 94, and moves contact 45 from a back point to a front point thereby causing signal I to give a proceed indication.

The control of the relay IG may also be made subject to traflic conditions to provide for semiautomatic control in the usual manner, all of which has been omitted for simplicity of the features of the present invention.

From the above, it is apparent that the operation of a signal lever conditions the route circuits, which if proper allow the clearing of the signal associated with that lever. This conditioning of the route circuit also prevents opposing signal levers from being effective, as the picking up of the route relay RR at the opposite end of the route prevents the pick-up of the lever repeating relay at that end of the route.

This part of the description is intended to point out that each signal lever can condition a route circuit, and that the response of such route circuit governs the resulting response of the associated signal. Thus, the pick-up and stick circuits for each relay P and the energizing circuit for each relay G will now be pointed out.

The pick-up circuit for the relay 4P may be closed from through a circuit including the lever 48L in a dotted line position, windings of relay 4P, back contact 46 of relay 4RR, to

The stick circuit for the relay 4P is closed after its response from through a circuit including the lever 4SL in its dotted line position,

- windings of relay 4P, front contact 41 of relay 4P, to The energizing circuit'for the relay 4G is closed with relays 4P and IRR picked up from through a circuit including front contact 48 of relay 4BR, front contact 49 of relay 4P, windings of relay 4G, to When the relay 4G is picked up the stop indication of the Signal 4 is removed and a proceed indication is established.

The pick-up circuit for the relay 3P may be closed from through a circuit including lever 3SL in its dotted line position, windings of relay 3P, back contact 5!] of relay 3BR, to The stick circuit for the relay 3]? is closed after its response from through a circuit including lever 3SL in its dotted line position, windings of relay 3P,'front contact SI of relay 3P, to The pick-up circuit for the relay 3G is closed with relays BP and 3BR picked up from through a circuit including front contact 52 of relay 3BR, front contact 53 of relay 3P,- windings of relay 3G, to When the relay 3G is energized, the red indicator of the sig-' ma] 3 is ole-energized and the green or proceed indicator of the signal 3 is energized.

The pick-up circuit for the relay 2P may be closed from through a circuit including lever ZSL in its dotted line position, windings of relay 2P, back contact 61 of relay 2BR, to The stick circuit for the relay 2P is closed after its response from through a circuit including lever ESL in its dotted line position, windings of relay 2P, front contact 68 of relay 2P, to The pick-up circuit for the relay 2G is closed with the relays 2P and 2BR picked up from through a circuit including front contact 59 of relay 2BR, front contact of relay 2P, windings of relay 2G, to When the relay 2G is energized, open back contact II de-energizes the red indicator of the signal 2, and the closed front contact lI energizes the green indicator of signal 2.

The pick-up circuit for the relay 6P may be closed from through a circuit including ing lever ESL in its dotted line position, windings of relay 6P, front contact 18 of relay 6P, to The energizing circuit for the relay 5G is closed with the relays SP and 6BR picked up from through a circuit including front contact 80 of relay 5BR, front contact 8I of relay 6P, windings of relay 6G, to I The pick-up circuit of the relay 5P may be closed from through a circuit including lever ESLin its dotted position, windings of relay 5P, back contact 63 of relay 5BR, to The stick circuit for the relay 5? is closed after its response from through a circuit including lever ESL in its dotted line position, windings of relay 5P, front contact 8 of relay 5P, to The energizing circuit for the relay 5G is closedwith the relays 5P and 5BR, picked up from through a circuit including front contact 86 of relay 5BR, front contact 31 of relay 5?, windings of relay 5G, to When the relay 5G is picked up, it opens back contact 88 to ole-energize the red indicator of the signal 5, and then closes front contact 88 to energize the green indicator of signal 5.

Route circuits Following the picln'ng up of a lever repeating relay P, the route circuit for the route governed by the associated signal is energized provided such route is actually set up over the trackway and provided the opposing signal has not been conditioned to be cleared. Also, in accordance with the present invention, certain of the route circuits are dependent upon trafiic direction checks and releases. The contacts and controls of these checks and releases will be included in the route circuits as pointed out in this section, although a detailed explanation of their operation will be considered separately.

Assuming that the track switch IZTS is in its normal locked position (as illustrated), and that the operator desires to clear the signal I, he moves the signal lever ISL to its dotted line position in which it energizes the relay IP through its pickup circuit. After the response of the relay IP, its stick circuit is closed.

The picking up of the relay IP closes its front contact 56, which completes a circuit for the route relays IRR, and 3BR closed from through a circuit including front contact 56 of relay IP, winding of relay IRR, front contact 51 of relay IZWP, polar contact 58 of relay I2W'P in its left hand normal position, windings of relay 3BR, back contact 60 of relay 3P, back contact I3 of relay ZRR, to The energization of relay IRR opens the pick-up circuit of the relay IP, but as its stick circuit is closed through its front contact 42, the relay IP is wholly dependent upon the lever ISL.

The energization of the relay 3RR opens the energizing circuit of relay 3P at the back contact 50 of relay 3BR, so that any subsequent actuation of the lever 3SL to its dotted line position does not energize the relay 3? nor interrupt in any way the route circuit already established. It is also apparent that if the levers ISL and 38L were operated simultaneously that would be applied to both ends of the circuit including relays IRR and 3BR so that they would remain deenergized.

Should the operator desire to establish the opposite direction of trailic over the track switch I2TS, then the lever 3SL should be actuated to its dotted line position and the lever ISL left in its normal position. This picks up the relay 3P which in turn closes the route circuit including the relays IRR. and 3BR from through a circuit including front contact 60 of relay 3P, windings of relay 3BR, polar contact 58 of relay IZWP in a left hand normal position, front contact 5'! 'of relay IZWP, winding of relay IRR, back contact 56 of relay IP, front contact 64 of relay is, to This energization of the route circuit causes the relay 3P to be wholly dependent upon the lever 3SL, and also prevents the control of the relay IP by the lever ISL by reason of open back contact II.

When the track switch IZTS is in a reverse position, then the operation of the lever ISL establishes a route circuit for relays IRR and 4BR in series from through a circuit including front contact 56 of relay IP, windings of relay IRR, front contact 5'! of relay I2WP, polar contact 58 of relay IZWP in a right hand position, winding of relay 4BR, back contact 59 of relay 4P, to It is apparent that the energization of this route circuit causes the relay IP to be wholly dependent upon the lever ISL, while the control of relay 4P by its lever 4SL is prevented by reason of open back contact 46 of relay 4RR.

If the opposite direction of traffic is desired over the reverse route including the track switch I2TS in its reverse position, then the lever fiSL is actuated which picks up the relay 6P. This closes the route circuit including the relays IRR and 4RR from through a circuit including front contact 59 of relay 4P, windings of relay 4BR, polar contact 58 of relay IZWP in a right hand reverse position, front contact 51 of relay I2WP, windings of relay ERR, back contact 56 of EP, front contact 64 of relay IS, to It is apparent that the energization of this route circuit causes the relay GP to be wholly dependent upon its lever lSL through its stick circuit including front contact 4?, and prevents the relay IP from control by reason of open back contact 4| of relay IRR.

Attention is now directed to the interlocked group on the right hand portion of Fig. 1. Let us assume that trafiic is to be established over the track switch HTS in a normal position in an east bound direction. The operator moves the lever 2SL to its dotted line position in which the relay 2P is picked up which closes the route circuit including the relays ZRR and 5BR from through a circuit including front contact 12 of relay 2P, windings of relay ZRR, front contact 15 of relay MWP, polar contact 16 of relay MWP in a left hand position, windings of relay ERR, back contact of relay 5P, front contact 93 of relay 5S, to The energization of this route circuit causes the relay 2P to be wholly dependent upon its lever ZSL, and prevents the relay 5P from being energized by its lever ESL by reason of the opening of back contact 83 of relay ERR.

If the opposite direction of trafiic over this route is desired, then 58L is operated to its dotted line position and relay ZSL is left inits normal position. This causes the picking up of the relay 5P which in turn closes a circuit for the relays 2RR and 5RR from through a circuit including front contact 85 of relay 5P, windings of relay 5RR, polar contact 16 of relay IL WP in a left hand normal position, front contact E5 of relay WP, windings of relay ZRR, back contact 12 of relay 2P, back contact 65 of relay 3RR, to The energization of this route circuit causes the relay 5P to be wholly dependent upon its lever 5SL, and prevents the control of relay 2P by its lever 2SL.

With the track switch MTS in its reverse position, then either of two opposite directions of traflic may be established over the track switch in such reverse position depending upon whether the lever ZSL is operated to its dotted line position or whether relay ESL is operated to its dotted line position.

When the lever ZSL is operated to its dotted line position, then the relay 2P is picked up which closes the route circuit including relays ZRR and ERR from through a circuit including front contact 72 of relay 2P, windings of relay 2BR, front contact 75 of relay MWP, polar contact 16 of relay IAWP in its. right hand reverse position, windings of relay BRR, back contact 19 of relay GP, to

The energization of this route circuit causes the relay 2P, to be wholly dependent upon its lever ZSL by reason of the opening of its pick-up circuit at contact 67, and the relay BP is prevented from response to the lever tSL by reason of its open contact 71.

If the lever 6SL is operated to its dotted line position and the lever ESL is left in its normal position, then the relay BP is picked up clos n e route circuit including the relay ZRR and ERR" from through a circuit including front contact 19 of relay 6P, windings of relay GRR, polar contact 76 of relay MWP in a right hand normal position, front contact 55 of relay HSWP, windings of relay ZRR, back contact 12 of relay 2P, back contact 65 of relay 3RR, to The energization of this route circuit causes the relay GP to be wholly dependent upon its lever ESL by reason of the open back contact 11, and prevents the control of the relay 2P by the lever 2SL by reason of the open back contact 6?.

From the above specific descriptions of the route circuits, it is apparent that each route circuit corresponds to the actual track layout in each interlocked group, is energized at that end from which trafiic is to proceed, and, when thus energized, prevents the energization of such route circuit from the opposite end.

Traflic direction control between groups-We may now consider how the opposing signals such as signals 1 and 5 in the two separate interlocked groups are prevented from being cleared at the same time. Let us assume that the lever ISL is operated to its dotted line position with the track switch I2TS in .its normal position. This causes the energization of the relay IP which in turn energizesthe relays l RR and 3RRwhich prevents the energization of the relay 3P by the lever 38L within the same group.

It is noted that the energizing circuit for these relays IRR and 3BR includes a back contact 13 of the relay 2BR of the other group. Thus, if the route circuit for either the signal 5 or the signal 6 is energized, then the energization of the route relays l RR and 3RR by the lever ISL is prevented, and the signal I cannot be cleared. In other words, the signal I cannot be cleared when either the signal 5 or signal 6 is cleared. Of course the opposite is true also, that is, the signals 5 and 6 are prevented from being cleared when signal I is cleared for reasons understood by analogy.

However, if the signal 2 is cleared by reason of the actuation of the lever ZSL to its dotted line position, then the energization of the relay ZRR does not prevent signal from being cleared,

because the relay 2? is picked up which closes front contact 14 applying negative potential to the wire 95 so that the relays IRR and 3RR can be energized upon the actuation of the lever ISL. In other words, corresponding directions of trafiic may be established in the two adjacent interlocked groups, but opposing directions of traffic are positively prevented.

It is to be noted, that, if the route circuit including the relays IRR and SRR is energized resulting in the clearing of signal I, such clearing of the signal I can not be interrupted by the putting to stop of the signal 2, if it had been cleared, because of the closed front contact 65 of the relay iiRR which applies to the back contact 63 of the relay 3P. In other words, assuming the signal 2 to be at stop and the signal I to be cleared, the actuation of the lever ZSL to its dotted line position and the successive response of the relays 2P and ZRR cause to be applied to wire 95 by front contact M before back contact '53 opens; but, when the signal 2 is cleared and the lever ESL is returned to stop while the signal which is still clear, the relays 2P and ZRR drop away in succession so that front contact M is open before back contact i3 is closed. This would cause the momentary deenergization of the circuit for relays IRR and 3RR locked groups are positively prevented from being cleared at the same time in accordance with the present invention. In the provision of this directional control, it isalso necessary that the direction of traffic cannotbe changed immediately upon the operation of the signal levers but shall be [delayed for a sufiicient time to allow for the safe passage of traffic in a manner now to be considered.

. Irrespective of whether the track section l3 intervenes between the signals 3 and 2 or whether the signals 2 and 3 are opposite each other, provision must be made that the signal I can not be cleared immediately after, the signal 3 is put to stop in the face of an approaching train, as this condition might allow two trains to move in opposite directions towards each other without any intermediate signals. to prevent a head-on collision. This alsov applies to the movement of traffic in the opposite direction.

Let us assume that a train is approaching the signal I which has been cleared by'reason of the operation of the leverISL to its dotted line position. The energization of the relay IG to clear the signal I through frontcontact 45, also deenergizes. the stick relay IS at back contact 94. As pointed out above,under such a condition the signal 3 cannot be cleared because of the open contact 50 included in the circuit for the relay 3P. Also, should the operator return the signal lever ISL to its normal position deenergizing the relay IP and the relay IG to put the signal I at stop,v the signal 3 cannot be cleared in response to the operation of the lever SSL until after a predetermined time measured by the thermal relay ITR.

, More specifically, the deenergization of the relay IP and closure of its back contact 56 upon the restoration of the lever ISL, closes a circuit from 1+), through a circuit including back contact 64 of relay IS, back contact 56 of relay IP, windings or relay IRR, front contact 51 of relay IZWP, polarv contact58 of relay I2WP in a left hand normal position, windings of relay 3BR, back contact 60 of relay 3P, front contact 65 of relay 3RR, to The relay 3RR is made slightly slow acting so that'its contact 65 remains closed, while the contact56 of the relay EP moves from a front point to a back point position. Thus, the relays IRR and ERR are maintained energized upon the dropping of the relay IP, so that the relay SP is prevented from responding to the lever ESL at open back contact 58.

'Upon the closure of back contact 94 of relay IG' following the dropping away of the relay IP, energy is applied to the thermal relay ITR by a circuit closed from through a circuit including back contact 94 of relay IG, winding of thermal relay ITR, back contact SI of relay IS, to The current flowing in this, circuit causes the thermal relay after a time to close front contact 63 to pick up the relay IS which thencloses its stick circuit through front contact BI as heretofore pointed out. The opening of back contact BI and the inclusion of the winding of relay IS in the circuit of the thermal relay winding increases the resistance of the circuit to such a value that the current, although suflicient to hold the relay IS energized, is insufficient to maintain the thermal relay actuated so that after a time the thermal relay restores to normal.

As soon as the back contact 54 of the relay IS is open, the relays IRR and3RR are deenergized so that the relay 3P can respond to its lever by reason of the closure of back contact 59. The relays 3BR and IRR can then respond immediately as soon as relay 3P picks up.

From this it is seen that the response of the relays 3P and 3BR to the actuation of lever 3SL to energize the relay 3G and clear the signal 3 is delayed, following the restoration of the signal lever ISL to its normal position, a predetermined time measured by the thermal relay ITR. This allows sufiicient time for the train approaching the signal I to stop in approach to such signal.

Under the circumstances just described, the delay period measured upon the restoration of the lever ISL is not only imposed upon the signal 3, but is also imposed upon the control of the signals 5 and 6 in the next adjacent interlocked group. This is accomplished by reason of the fact that relay 3BR is not de-energized until the relay IS is picked up, and, as back contact 65 of relay 3BR is included in the route circuits for the signals 5 and 6, the relay ZRR and either relay 5BR or relay 6BR cannot be energized until after the delay period measured by the thermal relay ITR.

It will be apparent from the consideration of TR and stick relays S, each of the remaining signals of Fig. 1 are preferably provided with similar apparatus.

Such an arrangement as provided in Fig. l. in accordance with the present invention, serves to prevent the quick reversal of traflic direction by quick manipulation of the signal levers thereby giving'adequate protection to the movement of trains within and between two adjacent interlocked groups both where the track section I3 is present between the signals 2 and 3 and where the signals 2 and 3 are substantially opposite each other.

Modification (see Figs. 3A and 3B) .-The principles of the present invention, as disclosed in Fig. l of the accompanying drawings, have been also illustrated in Figs. 3A and 3B which, when placed end to end, illustrate a more extended track layout. The simplified layout of Fig. l was chosen in order to simplify the detailed discussion of the operation, but the more extended track layout of Figs. 3A and 3B has been chosen to indicate conventionally how the invention may be applied to more complicated track layouts.

The track layout of Figs. 3A and 3B includes a stretchlof track which is divided into sections Ill, H2, H3 H4, H5, H6, H1 and H8. The track sections H2, H4, H6 and H8 include railway track switches HZTS, HATS, HBTS and HBTS respectively. These track switches serve to connect turnout track sections to the main track the usual way. The track sections H3, I I5 and I I! are illustrated as traffic sections connecting the successive interlocked groups and correspond to the section I3 of Fig. 1. These sections may be omitted in practice where the interlocked groups are close together the same as mentioned in connection with section I3 of Fig. 1.

Each of the track sections including a track switch have been shown as having signals governing the entrance of traffic into such sections in both directions. These signals IOI, M3, I05, I01, I02, I04, I06 and I08 may be readily identified with the respective sections from the drawings, and are controlled by their respective G relays identified by reason of the distinctive numerals preceding the letter reference character G.

Certain of the relays have been shown in block without control circuits, while certain other relays have their control merely indicated, all of which is for the purpose of simplicity in the illustration of the extension of the invention.

For example, the relays WP for the respective track switches have been omitted, but certain of their contacts merely indicated by an at in the respective route circuits which have been shown.

The signal levers, the control circuits for the signals, and various other features shown in Fig. l have been omitted from Figs. 3A and 3B, but they should be considered as employed in connection therewith.

Lever repeating relays P are associated with their respective signals, as indicated by their preceding numerals. Likewise, route relays RR are associated with their respective signals, as indicated by their preceding numerals.

Signal relays G are associated with their respective signals, as designated by the numerals preceding their letter reference characters; and each of these relays, when deenergized, causes its associated signal to indicate stop or clear depending upon whether it is deenergized or energized respectively, as has been illustrated in Fig. 1.

A time element relay TR and a stick relay S is shown as associated with each of the signals of the track layout, as designated by the numerals preceding their letter reference characters.

As each of the signals is provided with its own time release thermal relay TR and stick relay S, the interconnection between the interlocked groups are connected to the relays RR and S instead of through the relays RR and P as indicated in' Fig. 1, where only the signals I and have time releases and stick relays.

For example, the route circuit for the relays IGERR and IBGRR may be closed, when the relay MP is picked up, from through a circuit including front contact I20 of relay I06P, windings of relay I06RR, contacts of relay II4WP (not shown), windings of relay I03RR, back contact I2I of relay I03P, front contact I22 of relay I03S, back contact I23 of relay I08RR, to The picking up of contact I24 of relay I03RR applies potential from to front contact I22 in place of back contact I23. This function of front contact I24 corresponds to the function of front contact 73 of relay 2BR of Fig. 1, for example.

Each of the route circuits includes contact corresponding to contact I 22 of relay I03S for the purpose of delaying the reversal of traflic direction similarly, as described for the contact (24 and 93 of Fig. 1. It is desired to point out, that the time control of the relay IOIS is effective to prevent the clearing of the signal I06 for a predetermined tlme after the putting to stop of the signal IIII; but such control does not extend to the signal I04. In other words, the time release for each signal governs the reversal of trafiic direction in the section which it immediately governs, the trafl'ic section connecting two interlocked of Figs. 3A and 3B is unnecessary, as the circuits will be readily understood by analogy to Fig. 1.

OPERATION (FIGS. 2A AND 2B) Normal conditions.The track switches 2ITS 24TS have been shown in their normal conditions with their respective switch machine control levers (not shown) in correspondence therewith. Similarly, the signal control levers are shown in their at stop positions so that their respective signals are displaying stop indications.

More specifically, the red lamp of signal 3IA is energized through back contact 200 of relay 3IAG; the red lamp of signal 3IB is energized through back contact 20I of relay 3iBG; the red lamp of signal M C is energized through back contact 202 of relay 3ICG; the red lamp of signal 36A is energized through back contact 203 of relay SBAG; the red lamp of signal 360 is energized through back contact 204 of relay 360G; the red lamp of signal 34 is energized through back contact 205 of relay 34G; the red lamp of signal 32A is energized through back contact 206 of relay 32AG; the red lamp of signal 32B is energized through back contact 201 of relay 32BG; the red lamp of signal 32G is energized through back contact 208 of relay 320G; the red lamp of signal 33A is energized through back contact 209 of relay 33AG; the signal 33C is energized through back contact 2I0 of relay 330G; and, the red lamp of signal 35 is energized through back contact 2 of relay 35G.

The various track sections are preferably provided with track circuits of the usual type of which sections 2|, 22, 23 and 24 are illustrated as provided with the usual track batteries and track relays T with suitable preceding numerals to designate the sections with which they are employed. With these closed circuit type of track circuits, the track relays are normally energized.

The switch repeating relays WP are energized in accordance with the normal positions of their respective track switches, as above mentioned, thus causing the circuits with which they are associated to be selected in accordance with the normal positions of the track switches.

With the signal control levers SL in their at stop positions, the stick relays S are energized through their respective stick circuits, which will be presently set forth. The pick up of these relays S is accomplished either by the elapse of a time measured by their respective thermal relays TR, as described later, or by other types of releasing means not shown but commonly used in approach and detector locking when the time period measured by the thermal relays is not required.

The stick relay 3IS is maintained picked up by a stick circuit closed from through a circuit including back contact 2I2 of relay 3IAG, back contact 2I3 of relay 3ICG, back contact 424 of relay 3 IBG, heating winding of the thermal relay 3I TR, front contact 2 M of relay 3IS, windings of relay 3IS, to The current, which flows in this circuit to maintain the relay 3IS energized, is insufiicient to actuate the thermal element of the relay 3 ITR.

The stick relay 338 is maintained picked up by a stick circuit closed from through a circuit including back contact 3 I4 of relay 35G, back contact 2| 5 of relay 33AG, back contact 2I6 of relay 330G, winding of thermal relay 33'IR, front contact 2H of relay33S, windings of relay 338,

to The current, which flows in this circuit to maintain the relay 33S energized, is insufficient to actuate the thermal element of the relay 33TR.

The track sections 2! and 24 including the track switches 2ITS and '24TS preferably have associated therewith suitable directional stick relays for each direction of which only the relays ZIES and 24WS have been shown. The relay 2|ES is normally energized by a circuit closed from through a circuit including back contact 222 of relay 3lP, back contact 223 of relay 3 3ITR, front contact 224 of relay 3| S, front contact 225 of relay ZlT, windings of relay H138, to The relay 2IES is provided with front contact 221 which shunts the track relay contact 225, thereby making this relay 2 IES a stick relay with respect to the track relay 2 IT.

The relay 24WS is energized by a circuit from through a circuit "including back contact 2| 8 of relay 33P, front contact 219' of relay 33S, back contact 220 of thermal relay 33TR," front contact 22| of relay 24T, windings of relay 24WS,

to The relay 24WS includes a front contact 226 which shunts track contact 22!, thereby making the relay 24WS a stick relay with respect to the track relay 24T.

The lock relays (not shown) for the track switches are selected through contacts of the associated relays G, ES and WS. In other words, whenever a signal is cleared the'switch is" locked against operation, and the directional stick relays ES and WS for each switch maintain such locking when the train accepts the route and until after it passes beyond the associated detector track section.

With the conditions illustrated, the traffic direction circuit for relays EF and WF is closed.

from (B+), through a circuit including directional lever DR in a right hand position, back contact 228 of relay 36RR,back contact 229 of relay 3GP, windings of relay EF, line wire 230, windings of relay WF, back contact 23! of relay 32P, back contact 232 of relay 32RR', to (CN). The current which flowsin this circuit causesthe polar contacts of the relays EF and WE to be actuated to their right hand positions.

be applied to this circuit from (B), which would cause current to'fiow in the circuit in the opposite direction resulting inthe actuationof the polar" contacts of these relays toleft hand positions.

With the directional relays EF and'WF having their polar contacts in right hand positions, the relay 3IHD is conditioned in accordance with traffic in advance of the signalBl {but if the contacts of the relays'EF and WF wereintheir oppo- 23T, line wire23 i', front contact 242 of relay 22T,

polar contact 2M- of relaylilFin a right hand position, windings of relay 3IHD, polar contact 243 of relay EF in aright hand position, front contact 239 of'r'ela'y 2 2T, line 'wire'233 front con- It will be apparent, that, if the lever DR were operated to the opposite or left hand position, potential would tact 238 of relay 2.3T, polarcontact 231 of relay WF, back contact 245 of relay 33AG, to

On the other hand, if the relays EF and WP have their contacts actuated to the opposite or left hand positions, a circuit is closed for the relay 33HD from through a circuit including front contact 28I of relay 2 ES, polar contact 246 of relay ZIWP in a left hand position, front contact 24! of relay ZIWP, back contact 248 of relay 36AG, polar contact 240' of relay EF in a left hand position, front contact 239 of relay 22T, line wire 233, front contact 238 of relay 23T, polar contact 25 of relay WF in a left hand position, windings of relay 33HD, polar contact 244 of relay WF in a left hand position, front contact 243 of relay 23T, line wire'234, front contact 242 of relay 22T, polar contact 24I of relay EF in a left hand position, back contact 249 of relay 36AG, to

Establishing a route.Let u's assume that a train is approaching the signal 3| upon the track section 2% and that the operator desires to send this train over the main track to the signal'32 and from thence over the track switch 24TS in a reverse position on to the turn-out track section 21.

To do this, the operator first positions the switch control levers (not shown) for the track switches ZITS and 24TS so that these track switches assume normal and reverse positions respectively. The operator'then actuates the direction lever DR to a right hand position (as now shown) which causes the polar contacts of the relays EF and WP to assume right hand positions. Following such actuation of the directional control le'ver, the operator may then position the signal levers 3|SL and 325313 to their right hand positions. Although the above sequence of direction and signal lever operation is preferable,theorder may be changed and still obtain the same results.

'With the lever 3|SL in a right hand position, a circuit is closed for the relay 31? from (3+) through a circuit including lever 3 ISL in a right hand dotted line position, windings of relay 3I'P, back contact 253 of relay. 3|RR', to (CN). As soon as relay 3 IP picks up, a stick circuit is closed from (B+), through a circuit including lever 3| SL in a right hand position, windings of relay 3,|P, front contact 25! of relay 3IP, to (CN).

With the track switch 2 ITS in its normal position, the response of the" relay 3'IP can immediately close the route circuit for relays 3'IRR and "35RR. in series. This route circuit is closed from through a circuit including front contact 252 of relay 3|P, windings of relay 3|RR, front contact 253 of relay Z'IWP, polar contact 254 of relay 2 IWP in a left hand position, windings of relay '36RR, back contact 255 of relay 35F, polar contact 256 of relay EF in a right hand position, to'

The energizationof the relay 31F from (B+), causes'its polar contacts to be operated toright hand positions. Thus, the response of the relay 3'lRR causes the re1ay'3IAG to be'energ'ized by a circuit closed from ,through a circuit including front contact 251 of relay 3IRR, front contact 258 of relay 3|P, polar contact 259 of relay 3|P in'a right hand position, front contact 260 ofrelay 2IT, front contact 26! ofrelay 2-IWP, polar contact 262 of relay" ZIW'P in a left hand position, front contact 263 ofrelay'3lI-1D, windings-of relay 3 IAG, to The-picking up of the contacts of the relay 3IAG"op'e'r"1s the energizingcircuit of the red lamp'ofthe signal 3iA at back contact 230 and closes the circuit for either the green lamp or the caution lamp of signal 3IA through front contact 260 depending upon the position of the polar contact 264 of relay 3IHD. If the signal 32A is still at top, then the relay BIHD will be energized, as above pointed out, with its polar contact 264 in a left hand position, thereby energizing the caution indicator of the signal MA by a circuit obvious from the drawings. On the other hand, if the signal 32A is cleared the polarity applied to the relay 3II-ID is reversed by contacts 236 and 245 of relay 32AG, so that the polar contact 264 of relay Bil-ID assumes a right hand position to energize the green indicator of the signal HA.

In the particular situation under consideration, the signal 323 is to be cleared to allow the train to pass on to the turn-out track section 21. Thus, the signal 32A will remain at stop and the relay 3IHD remains energized as shown, so that only the caution indicator of the signal BIA may be cleared at this time.

The clearing of the signal 3 IA by the energization of the relay 3IAG opens the stick circuit of the relay SIS at back contact 2I2 of relay MAG. Also, the response of the relay SIP to its pick up circuit opens the energizing circuit for the relay ZIES at back contact 222. The purpose of these controls will be pointed out hereinafter.

The actuation of the signal lever 32SL to a right hand position closes a circuit for the relay 32F from (B+), through a circuit including lever 32SL in a right hand position, windings of relay 32F, back contact 265 of relay SZRR, to (CN). The response of the relay 32P closes a stick circuit for the relay 32]? from (B+) through a circuit including lever 32SL in a right hand position, windings of relay 32F, front contact 2165 of relay 32F, to (CN).

The response of the relay 32F closes the route circuit for the relays SZRR and 35RR in series from through a circuit including front contact 261 of relay 32F, windings of relay 32RR, front contact 268 of relay ZtWP, polar contact 269 of relay 24WP in a right hand position, windings of relay 35RR, back contact 21%] of relay 35F, to

The energization of the relay 32P from (B+) causes its polar contacts to be operated to right hand positions, so that the response of the relay SZRR closes an energizing circuit for the relay 3ZBG from through a circuit including front contact 2' of relay BZRR, front contact 272 of relay 32F, polar contact 213 of relay 32F in a right hand position, front contact 214 of relay 2 1T, front contact 215 of relay ZAWP, polar contact 276 of relay MWP in a right hand position, windings of relay 32BG, to

The picking up of the contacts of the relay 32BG opens the energizing circuit for the red or stop lamp of signal 32B at back contact 201 and energizes the proceed indicator of signal 323 through front contact Zill. As this is the diverging route, presumably requiring low speed, the signal energized by the front contact 26? will preferably give a caution indication. It is for this reason that the polarity on the relay SIHD is not reversed upon the clearing of signal 32B, but if the signal 323 displays high speed proceed indication such as green, then the relay 32BG would also be adopted to reverse the polarity on the relay 3II-lID.

As soon as the signal 3 IA indicates proceed, the train passes from section 20 over the sections ZI, 22, 23, 24 on to the section 21 in succession. The deenergization of the track relay ZIT opens the energizing circuit of the relay 3IAG at front contact 260 so that the signal BIA is caused to display stop as soon as the train has accepted sucn signal. The train proceeds onto the section 22 deenergizing track relay ZZT which opens the energizing circuit of the relay 3lHD at contacts 239 and 242. This deenergization of relay 3II-ID opens the energizing circuit for relay 3IAG at front contact 263. Likewise, the train on the track section 23 opens the energizing circuit for the relay 3II-ID at contacts 238 and 243. Thus, it is seen that the signal 3 IA is maintained at stop until the train passes beyond the signal 32.

It will be noted that with the signal lever 3ISL in a right hand proceed position resulting in the energization of the relays 3IRR and 36RR in series, the circuit for the control of relays EF and WF by the directional lever DR is broken at back contact 228. The energization of the relay 32P opens the circuit controlling the relays EF and WP at back contact 23I and closes it through front contact 23! to (CN).

Thus, it is readily apparent that the directional lever DR, if operated under these circumstances, is ineffective to disturb the signal 3IA from its clear position-so long as the control lever for such signal is in clearing positions, although the initial clearing of the signal is dependent upon the directional lever being in the proper position.

After the train passes onto the track section 21, and when the signal levers have been returned to stop, the system returns to its normal condition as illustrated.

Directional time release.--Let us assume that the operator has set up the route as above described but with HTS in a normal position in anticipation of the train approaching the signal SIA, but for some reason he desires to reverse the direction of trafiic and allow a train to pass from the signal 33A onto the sections 24 and 23., This route is established after the operation of signal levers 3ISL and 32SL, to stop.

Such reversal of traffic direction is delayed for a predetermined time in accordance with the time measured by the thermal relay SITR. This delay is provided by the present disclosure of Figs. 2A and 2B irrespective of whether a train is approaching the signal 3! on section 2|! or not. However, the usual approach locking type of release may be employed in connection with the relay 3| S so that it is dependent for its pick up through the elapse of a time measured by relay 3ITR only when the track section 29 is occupied. Such an arrangement would then permit reversal of traflic direction in the section including track sections 22 and 23 without the elapse of time providing there was no train approaching the signal 3|.

However, in accordance with the present disclosure, in order to establish trafiic in a west bound direction the operator must first return the levers 3 ISL and. 32SL to their stop positions, then actuate the direction lever DR to a left hand dotted line position after which he operates the lever 33SL to its left hand dotted line position. As soon as the relay 36RR becomes deenergized closing back contact 228 and relays 32F and SERR. become deenergized closing back contacts 2M and 232, the direction relays EF and WE actuate their contacts to left hand positions in response to the application of energy from (3-).

The actuation of the lever 33SL to a left hand position closes a circuit for relay 33? from (13+) through a circuit including lever 33SL in a left hand position, winding of relay 33F, back contact 211' of relay 33RR, to (ON). As soon as the relay 33].? picks up, a stick circuit is .closed from (B+), through a circuit including lever 33SL in a left hand position, winding of relay 33P, front contact 218 of relay 33F, to (CN) With the relay 33P picked up and the polar contact 280 of the relay WF actuated to its left hand position, the route circuit for the relays 333R and 32RR in series is closed from through a circuit including front contact 219 of relay 33P, windings of relay 33RR', polar contact 269 of relay 24WP in a left hand position, front contact 268 of relay 24WP, windings of relay 323R, back contact 261 of relay 32F, polar contact 280 of relay WF in a left hand position, to The picking up of the relay 33RR with the relay 33P picked up tends to close a circuit for energizing the relay 33AG, but the relay 33AG cannot be energized until the relay 331-113 is energized which in turn is dependent upon the closure of contact 281 of relay 2l ES which is not picked up until after the predetermined time measured by therelay BITR.

For example, the deenergization of the relays 3IRR and 3| P deenergizes the relay 3|AG which completes an energizing circuit for the winding of the thermal relay 3ITR from through a circuit including back contact 2l2 of relay 3IAG, back contact 2l3 of relay 3ICG, winding of relay 3ITR, back contact "2l4 of relay MS, to

, After a time the front contact 282 of the thermal relay 3|TR is closed which shunts out the contact 2| 4 causing the relay MS to be energized.

The picking upof relay 3| S opens back contact 2|4 causing the relay MS to be stuck up, as previously pointed out. The current in this stick winding is of course insuffi'cient to cause the thermal contacts of the relay 3lTR. to remain actuated so that they return to their normal deenergized back positions.

. After the thermal relay 3ITR has heated and cooled, a pick up circuit is closed for the relay 2 IES from through a circuit including back contact 222 of relay 3IP; back contact 223 of relay 3ITR, front contact 224 of relay 3IS, front contact 225 of relay 2|T, windings of relay ZIES, to The response of the relay 2IES shunts out the track relay contact 2 25 by front contact 221', as previously mentioned. 7

The closure of front contact 28| then closes the energizing circuit for the relay 33HD, as previously pointed out, after the predetermined time thus measured, so that the relay 33AG can then be energized by a circuit closed from through a circuit including front contact 283 of relay 33RR, front contact 284 of relay 33P, polar contact 285 of relay 33? in a left hand position, front contact 286 of relay 24T, front contact 281 of relay 33HD, windings of relay 33AG, to

This energization of the relay 33AG deenergizes the stop indicator red lamp of the signal 33A at back contact 209'and closes the circuit for energizing a caution or clear indicator depending, I upon the position of polar contact 288 of relay 33HD. Ifthe operator has not actuated the lever 3B SLto clear the signal 36, and such signal therefore remains at stop then the polar contact 288 will remain in its position as shown causing a caution or slow speed indication to be given by the signal 33A. On the other hand, if the operator actuates the lever 36SL and the signal 36A is cleared after the predetermined time measured by the relay 3| TR, then the polaritywill be reversed on the relay 331D) by contacts 249 and 248 of relay 36AG thereby allowing a high speed indication to be given by the signal 33A.

It may be well to note at this point the manner in which the thermal relay 3ITR also delays the clearing of the signal 36A.

The actuation of the lever 36SL to a left hand dotted line position applies energy to the relay 3GP through a circuit closed from (B+), through a circuit including a lever 36SL in a left hand position, windings of relay 3GP, back contact 300 of relay 36RR, to (CN). The response of the relay 36P closes front contact 3M which closes a stick circuit from (3+) through a circuit including lever 36SL in a left hand position, windings of relay 3GP, front contact 3M of relay 3GP, to (CN).

The picking up of the relay 36? tends to close a route circuit for the relay 36RR. and 3|RR in series, but this route circuit cannot be closed unless the thermal relay 3ITR is in a normal deenergized position and the relay 3IS is picked up. Thus, upon the restoration of the signal lever 3|SL to a stop position and the actuation of the lever 36SL, the signal 36A can not be cleared until after the predetermined time measured by the relay 3 ITR.

Assuming that the relay 3IS is picked up, as above described, and that the thermal relay 3 ITR has cooled to its normal position, then the route circuit for the relays 3IRR and 36RR is closed from through a circuit including front contact 255 of relay 3GP, windings of relay 36RR, polar contact 254 of relay 2IWP in a left hand position, front contact 253 of relay 2IWP, windings of relay 3IRR, back contact 252 of relay 3| P,

back contact 302 of relay 3ITR, front contact 303 of relay 31S, to

The response of the relay 36RR with the relay 3GP picked up closes an energizing circuit for the relay 36AG dependent on traffic conditions in advance as repeated by the relay 36I-ID, the control of which is not shown but may be in accordance with the usual practice. This energizing circuit for the relay 36AG is closed from through a circuit including front contact 304 of relay 36RR, front contact 305 of relay 3GP, polar contact 386 of relay 36P in a left hand position, front contact 301 of relay 36HD, windings of relay 36AG, to The picking up of contact 293 of relay 36AG deenergizes the stop indicator of the signal 36A and energizes the caution or clear indicator of the signal 36A depending upon the position of polar contact 338 of relay 36 I-ID in accordance with the usual control.

7 Let us consider that this train accepts the signal 33A and proceeds over the track sections 24, 23 and 22 to accept the signal 36A. The sections 22 and 23 may represent quite a distance so that the train in advancing in a west bound direction may be wholly located Within the section 22. It might readily happen under such circumstances that the operator would desire to move a switching engine and its cars from section 21 to section 25.

All that is necessary to do in a case of this type is to put the lever 33SL at stop, reverse the track switch 24TS and actuate the signal lever SESL' to its proceed position. The signal 35 will then respond, in a'manner analogous to the control already described, and allow the train to proceed on to track section 23 after which the signal lever 35SL is restored and the lever 32SL is actuated to clear the signal 32A. As the train switching movement onto the section 23 requires appreciable time, it is assumed that such time would be a relay 33F, front contact 389' of relay 335, back contact 3) of relay 33TR, to The energization of the relays 32F and SZRR causes the signal 33A to be cleared by reason of an energizing circuit closed from through a circuit including front contact 21! of relay 32RR, front contact 2'52 of relay 321?, front contact 213 of relay 32F in a right hand position, front contact 2M of relay 2 lT, front contact 275 of relay ZQWP, polar contact 2'56 of relay 24WP in a normal position, front contact 3! l of relay 32I-ID, windings of relay 32AG, to The energization of relay 32AG and the opening of its back contact 2116 causes the stop indicator of such signal 32A to be extinguished and such signal to indicate caution or proceed dependent upon polar contact 3 l 2 of relay 32I-ID which is controlled in accordance with traific conditions in advance of such signal. From the above it is apparent that with a train having passed into the sections 23 and 22 and in a west bound direction ready to accept the signal 36 and pass beyond it, the operator may clear the signal 35, which is a low speed signal independent of track circuit control, and allow a train to be switched into the section 23 and then move out into the section 25 all in response to signal control. It is to be understood in this connection that movements under signal control when such signals are of the type which may be termed call-on signals, that is, signals which are independent of track signal control, trains move under specific oral or written instructions, as well as signal indication, so that the acceptance of signal 35 does not mean that the train will necessarily follow the train which is to accept signal 36.

With reference to Figs. 2A and 2B and the above description, it will be seen that, when the signal MA is cleared and a train accepts such signal, thesignal MA is put to stop as soon as the train enters the track section 2| deenergizing the track relay 2lT by reason of opening front contact 260. The signal EIA is maintained at stop as the train passes through the sections 22, 23 and 2% by reason of the track relays 22T, 23'? and HT as repeated by the relay 24WS opening front contact 235. Similar control is effective for the opposite direction. Therefore, so long as a train is on any track section between signals 3! A and signal 33A, the direction of traffic cannot be reversed with regard to the high speed signals, such as signals 3IA and 33A. For example, as soon as a train enters the section 2! in response to signal 31A cleared, the front contact 225 of relay 2IT maintains the relay ZIES deenergized irrespective of the return of the signal 3lA to stop. As front contact 28! of relay 2|ES is included in the energizing circuit for the relay 33HD, it is apparent that the signal 33A could not be cleared as the front contact 28? of 33I-ID cannot be closed-under such circumstances.

In brief, the directional stick relays 2 IES serve to repeat the track relays both for the purpose of controlling the HD circuits and for the purpose of providing rear release looking for the track switches, which latter feature has not been disclosed in detail in this application, but it may be considered as a possible adjunct of the present disclosure in accordance with the present invention.

Also, from the above it will be apparent that it is necessary to have the direction lever DR operated in a direction corresponding to that direction in which traffic is to enter sections 22 and 23, but the lever DR does not have to be in a position corresponding to the direction in which trains are leaving such sections.

Opposing caZZ-on signal m'uements.l'n accordance with the present invention, call-on, signals are provided which are controllable by the operator independently of track circuit conditions but such call-on signals are made subject to the traffic direction lever DR. In order to best understand how the call-on signals are particularly useful as well as the manner in which they are made subject to the traffic direction lever, a particular set of circumstances best brings out the situation.

Let us assume that a train, that is, a car or two is standing upon the track section 22 and a switching engine desires to connect with such cars in order to take them into another part of the interlocking plant, and that such switching engine comes from the track section 28. Also, at the same time the operator desires to move a switching engine from the track section. 25 onto the section 23 and from thence into the section 21.

Inasmuch as there is a train standing on the section 22, the signal 3iA cannot be cleared so it is necessary for the operator to clear the callon signal 31C. He operates the lever 3ISL to a left hand dotted line position which closes energizing circuit for relay 3lP from (B), through a circuit including lever 3lSL in a left hand position, windings of relay 3iP, back contact 259 of relay 3IRR, to (ON). The response of the relay 35F closes front contact 25! com pleting a stick circuit. The current which flows in the pick up and stick circuits of the relay 3lP causes its polar contacts to be operated to left hand positions.

As soon as the relay SIP responds, it tends to close a circuit for the relays 3|RR nad 35RR in series, but it is apparent that such circuit is dependent on the polar contact 256 of relay EF. This means that the direction lever DR must have been operated to a right hand position. This allows the relays MRR and SGRR to be energized through a circuit previously pointed out.

With relays (HP and SIRR picked up an energizing circuit is closed from through a circuit including front contact 251 of relay 3IRR, front contact 258 of relay 311?, polar contact 255 of relay SIP in a left hand position, windings of relay SICG, to The energization of relay 310G opens back contact 202 and closes ront contact 282 which causes the stop indicator of call-on signal (NC to be extinguished and the proceed indicator to be illuminated.

The engine then 'moves past the signal 3H; to couple with the train standing on the section 22. The clearing of such signal 3IC causes the relay 31S to drop by the opening of contact 2l3, so that, when the operator puts the lever ElSL to stop and actuates the lever 36SL to the right, the signal 33A will clear only after lever 3iSL has been at stop for a predetermined period of time, as measured by the thermal relay 3|TR. The clearing of signal 36A allows the ccntact'228.

switching engine and train to which it is now coupled tomove westward.

While the lever 3|SL is in a clearposition energizing the relays -3lRR and 36RR in series, the directional lever DR may be operated to the left but does not effect the opposite energization of relays EF and WF by reason of open However, as soon as the lever 3|SL is put to stop, the contact 228 closes and allows thereversal ofrelays EF and WF, as will also the picking up of the relay 3GP and closure of front contact 229. 7

Assuming that the train on the section 22 has .not yet moved, and either back contacts 228 and 229 are both closed or front contact229 is closed. Then the relays EF and WF have responded to the'operation of lever DR to the left so that the signal 330 may be cleared by the actuation of the lever 33SL to the right. Under these circumstances, the signal 33A cannot be cleared at this time with the train on section 22, as the deenergization of track relay 22T opens contacts 239 and 242 which deenergizes the relay 33HD although the polar contacts of the relays EF and WF are in left hand positions. Thus, the operator moves lever 33SL to the right closing a pick up: circuit for the relay 33P by applying (B). The-response of relay 33P closes a route circuit 3 for; relays33RRand 32RR in series which is completed as the polar contact 280 is in a left hand position.

With both the relays :33RR and 33P picked up, the relay '33CG is energized by a circuit closed from through "frontcontact 283 of relay -33RR, front contact 284 of relay 33P, polar contactr285vof relay 33?. in a right hand position, windings of relay 330G, to The energization of relay 33G causes the signal ;33C to be reversed and the signal 32A may be cleared as previously described without the actuation of the direction lever DR.

From this it is apparent that-two trains may ,be moved in opposing directions into a trafiic section such as sections 22 and 23 under call-on [signals only when the tramc direction lever DR is operated in accordance therewith, and even thenthe call-on signalcan be cleared for only one-direction at a time.

.Fig. 4 illustrates the directional control circuit for relays EF and WF of Figs. 2A and 2B in a modified form in which such circuit is rendered subject to track circuitgcontrol and to the time release control provided for the signals which .govern the entrance of trains into the associated 4 with the only new 'referencecharacters being those of the additional contacts employed. For example; the track relays 22Tand 23T are illustrated as having front contacts-4M and 402 respectively included in the circuit for relays 'EF and WE. Likewise, the relays'2lES and 24WS have front contacts 403 and 404 respectively includedin the circuitfor relays 'EF and WF.

With this arrangement, whenever a train is on either or both of the track circuits 22 and. 23, the

a train on either or both of the track circuits 22 I and 23, either 'or both of the front contacts .40l or 402 areopened which prevents the reversal of the contacts of the relays EF and WF by the directional lever DR.

In Figs. 2A and 2Bthe direction of traffic was not permitted to be reversed in sections 22 and 23 except after a predetermined time in the control of the high speed entering signals, but such time release control was not included in-the control of the call-on signals. In this Fig. 4 where the contacts 403 and 404 of the relays HES and 24WS are included in the circuit for relays EF and WF, such relaysEFand WF cannot bereversed or actuated to opposite positions except after the predetermined times measured by there- -25 lays 3ITR and 33TRas such timing control is in the control of the relays 2IES and 24WSrespectively, as heretofore pointed out. As relays'EF and WF control both high speed and call-on signals, both types of signals are therefore subject to thesame control.

Thus, Fig. Afurnishes a, modification of Figs. 2A and 2B in which thedirection of traflic cannot be reversed, except after a predetermined time for all types of signals. -Also, track circuit lockingisprovided in which the reversal of traffic direction in a check locking section is positively prevented so that two trainscannot enter .such sections in, opposite directions under any circumstances, whatsoever.

SUMMARY An interlocking system has therefore been provided in accordance with the present invention which discloses the manner that two interlocked the release of the adjacent interlocked group up to the opposing signal in such adjacent interlocked group.

In the second case, the present invention illustrates the manner in which a trafiic lever is employed to register the potential traflic direction last established in the interconnecting traffic section with the control resulting from such lever required for the entrance of traflic into the section but is not required for the exit of traffic from such section. Also, the operation of the traffic lever, after a signal has once been cleared dependent upon the traffic lever, is ineffective to disturb such cleared signal.

The time release for one interlocked group is not only effective to prevent a reversal of traffic direction within its group until after a predetermined time but also is effective in the next adjacent group with respect to the high speed signals (see Figs 2A and 2B). The call-on signals are controllable independently of the time control with regard to separated interlocked groups, but such call-on signals within any one group are also dependent upon the time release means (see Figs. 2A and 2B). However, in Fig. 4 the call-on signals are also subject to time release for reversal of traific direction.

It is therefore believed that the present invention has clearly set forth a new and novel manner in which trafiic locking may be accomplished and which time release means may be employed therewith where all operating controls originate in a single central control ofiice.

Having thus described an interlocking system as one specific embodiment of the present invention, it is to be understood that various modifications, adaptations, and alterations may be applied to meet the requirements of practice without in any manner departing from the spirit or scope of the invention except as limited by the appended claims.

What I claim is:

1. In a tramc controlling system for railroads, a stretch of trackway, a signal at each end of said stretch for governing the entrance of traffic into said stretch from that end, a signal control lever for each of said signals, means governed by each of said control levers for at times clearing its respective signal, a directional control lever associated with said stretch, means allowing each signal control lever to initially clear its respective signal only provided said directional control lever is operated to a position corresponding to the direction governed by its respective signal, and means allowing each signal control lever to maintain its respective signal cleared independently of said directional control lever.

2. In a trafiic controlling system for railroads, a stretch of trackway, a signal at each end of said stretch for governing the entrance of trafiic into said stretch from that end, a signal control lever for each of said signals, means governed by each of said control levers for clearing its respective signal, a directional control lever associated with said stretch and having two positions corresponding to opposite directions of trafiic in said stretch, a polarized directional control circuit having cur rent flowing in one direction or the other depending upon the position of said directional control lever, relay means in said polarized directional control circuit distinctively responsive to the direction of current flow therein, means allowing each signal control lever to initially clear its respective signal only when said relay means has distinctively responded to a direction of current flow corresponding to the direction of traffic governed by its respective signal and for maintaining such signal in its clear condition when once cleared irrespective of the condition of such relay means, and means opening said polarized directional control circuit when one of said signals is cleared, whereby each signal control lever can maintain its respective signal clear independently of said directional control lever and whereby said relay means cannot be changed while a signal is clear.

3. In a traflic controlling system for railroads, a stretch of trackway, a signal at each end of said stretch for governing the entrance of trafiic into said stretch from that end, a signal control lever for each of said signals and having clearing and stop positions, a traffic direction lever associated with said stretch and having two positions corresponding to the opposite directions of trafilc in said stretch, means causing each signal control lever to clear its respective signal when such lever is in a clearing position only provided said trafiic direction lever is in a position corresponding to the direction of traffic governed by such signal, and means allowing either of said signals to be responsive to its said signal control lever and said trailic direction lever only a predetermined time after the signal control lever for the other of said signals has been put to a stop position.

4. In a trafiic controlling system for railroads, a stretch of railroad track divided into two sections, first and second signals for governing the entrance of trafiic into said sections respectively in one direction, a third signal for governing the entrance of traific into said sections in the opposite direction, a separate signal control lever for each of said signals with each of said levers provided with clear and stop positions, means associated with each of said levers and its respective signal for clearing such signal when said lever is in its clear position, interlocking means for allowing said signals to be cleared for only one direction at a time, and means allowing said first and second signals to be cleared in response to their respective levers only a predetermined time after said lever for said third signal has been put to its stop position.

5. In a traiiic controlling system for railroads, a stretch of trackway, a signal at each end of said stretch for governing the entrance of trafilc into said stretch from that end, a signal control lever for each of said signals, means governed by each of said control levers for clearing its respecetive signal, a directional control lever associated with said stretch and having two positions corresponding to the opposite directions of trafiic in said stretch, directional relay means operable to either of two conditions corresponding to opposite directions of traffic through said stretch, means allowing each signal control lever to initially clear itsrespective signal only when said directional relay means assumes a condition corresponding to the direction of traflic governed by the signal for that lever, means causing said directional relay means to assume one or the other of its two conditions in accordance with the position of said directional control lever only when said signals are at stop and said stretch of track is unoccupied by traflic.

6. In a traffic controlling system for railroads, a stretch of railroad track including a track switch, signals governing the entrance of traffic into said stretch in both directions, a control lever for each of said signals, means governed by each of said control levers for clearing its respective signal, interlocking means for allowing only one direction of trafiic to be established in said stretch at the same time, releasing means allowing said track switch to be operated only a predetermined time after said signals have been put to stop irrespective of the presence of a train approaching such signal, and means including said releasing means for allowing the direction of trafiic to be reversed in said stretch only after said predetermined time.

7. In a traific controlling system for railroads, a stretch of railroad track, signals governing the entrance of traific into said stretch in both directions, an individual control lever for each of said signals, means governed by each of said control levers for clearing its respective signal, interlocking means for allowing said signals to be cleared for only one direction at a time, timing means for said signals, means for setting said timing means into operation to measure a predetermined time whenever a signal is returned to irstop from a clear condition' -andzlmeans effective czthroughthe medium oflsaid interlocking means to prevent the clearing of. each signal in responseto its respective control lever .until after the other signal hasbeeniput to stop'for thepredetermined time measured by saidtiming. means.

, 8..In aztrafficcontrolling system forirailroads,

,. a stretch .of railroad track, first and second signalsfor governing the entrance and exit of trafiic 210,

into .:and from said stretchrespectively in one direction, a third signalforgoverningthe entrance of trafiic into said stretch in the opposite direction, a separate signaltcontrol lever for each by each of said levers for clearing its respective said (signal control meansto clear the signals for onlyoneldirection .at a time, and timing means automatically controlled by said signal control andsecondlsignals' to be cleared: in response to their respective levers only apredetermined time means for said third signal for. allowing said first after-said third signal has been put to stop.

.9. x In a trafiic'controlling system for railroads,

a-stretch of railway track, signals for governing theentranceof traffic in both directions over ,saidpstretch,of track an individual control lever for each of said signals,- means governed by each -;of'. said control levers for clearing its respective signal when actuated, a directional control lever @associated with said. stretch of track, means al- .lofwing the-iresponseofoneofsaid entering signals to its respective control lever only provided :.,they other of said entering signals is'at stop and said. directional control lever has been operated :to a position corresponding to the direction of .traflic governed bysaid one entering signal while -;said stretch of'track is unoccupied by a train, and means :preventing the operation of said directional control lever from interrupting a cleared I entering signal.

.. ,10.,In a trams controlling system for railroads,

.1 a stretch of railway. track, signals for govern- .control lever for each ofsaid signals, means track relay for each section, two signals including-the entrance and exit of traffic in both directions over said stretch of track, an individual governed, by each of, said control levers forclearing itsrrespective signal whenactuated, a directional control lever associated with said stretch ;one of said enter1ngs1gnals to its'respective conof track, means allowing the :response of each trol lever only provided the other of said entering signals is at stop and said directional control lever has been operated .to a position corresponding to the direction of traffic governed by said one entering signal while said stretch of 5 track isunoccupied bya' train, means allowing the response of said leaving signals to their respectivecontrol levers. only provided the entering signal for the corresponding end of said stretch of track is at stop, said means acting independently of said directional control lever, and means preventing the operation of said directional control lever from interrupting a cleared entering signal.

11. In an interlocking system for railroads; two interlocked groups, each group including a track switch and signals governing traffic in opposite directions with manual control means for each of said signals; a stretch of track interconnecting said two interlocked groups; a traffic direction control lever; and means for preventing the clearing of either of said opposing signals of said two interlocked groups in response to their respective manual control means when --said track switchesare'positioned to allow the --passage of trafiic-into said stretch of track if said traffic direction lever is not positioned for the samedirection of train movement and if the opposing signal is cleared, said means acting to allow the contemporaneous clearing of the respective -leaving signals for said stretch of said two interlocked groups in response to their respective manual control means irrespective of the position assumed by said'traflic direction lever.

. l2. In aninterlocking system for railroads; two interlocked groups, each group including a track switch, signals governing traflic in opposite directions oversaid track switch, a route circuit'for each route over said track switch and associated with said signals governing traffic over the corresponding route, manual control means foreach signal, means for energizing a particular route circuit in response to the actuation of the manual control means for a signal governing traflic in one direction over the corresponding route only when the manual control means for the signal governing traffic in the opposite direction over such route is at stop, means for clearing each signal in response to its said manual control means only when its associated route circuit is energized; a stretch of track interconnecting said two interlocked groups; a directional control lever for said stretch of track} and means preventing the energization of a route circuit in one of said'groups in response to the actuation of said manual control means for the signal in that group governing traflic over the corresponding route into said stretch of trackunless said directional control lever has been operated to a proper position for the direction of traffic governed by said manual control means while the corresponding route circuit of the other group'is deenergized'or is energized by the ac--,

tuation of the manual control means for the signalin that other groupfor establishing the .same direction of trafiic in such other group as -thesaid signal of the said one group.

13; In combination with a stretch of railway,

track including a plurality of track sections, a

' ing one at each end of the stretch for governing the movement of trafiic in opposite directions into the stretch, a signal relay and a manually controllable signal control relay for each ofsaid track relays.

L 14. In combination, a single track section connecting two multiple track portions, a signal at each end of said section for governing the movement of traffic into said section, a stick relay for each of said signals, a manually operable contact for each stick relay, a pick-up circuit for each stick relay including its manually operable contact and a back contact of the other stick relay, a holding circuit for each stick relay including its own front contact and its manually controlled contact, and a control circuit for each of said signals at times controlled by its corresponding stick relay.

15. In combination, a single track section connecting two multiple track portions, two signals including one at each end of said section for governing the movement of traific into said sec-

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