US2095621A - End-to-end communication system for railway trains - Google Patents

Description

0a. 12, 1937. s, M, VIELE 2,095,621

END-TO-END COMMUNICATION SYSTEM FOR RAILWAY TRAINS Filed June 2, 1956 4 Sheets-Sheet l W I TNESSES: I N VEN T013: yofi/md m 5 msmmymj WWW Oct. 12, 1937. 5. M vlELE 2,095,621

END-TOEND COMMUNICATION SYSTEM FOR RAILWAY TRAINS Filed June 2, 1936 4 Sheets-Sheet 2 [ml] ii 12/ W 6 i117 mf WITNESSES; INVENTOR:

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BY M TORNEYS.

Oct. 12, 1937. s. M VIELE 2,095,621

END-TO-END COMMUNICATION SYSTEM FOR RAILWAY TRAINS Filed June 2, 1936 4 Sheets-Sheet 5 HG: E

. WITNESSES: INVENTOR:

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Oct. 12, 1937.

S. M. VlELE Filed June 2, 1936 4 Sheets-Sheet 4 WITNESSES:

INVENTOR 5 Master M Vwla,

Patented Oct. 12, 1937 v 2,095,621

UNITED STATES PATENT OFFICE END-TO-END COMJVIUNICATION SYSTEM FOR RAILWAY TRAINS Sylvester M. Viele, Swarthmore, Pa.

Application June 2, 1936, Serial No. 83,052

20 Claims. (Cl. 246-8) My invention relates to end-to-end comtively low frequency wayside signal current in munication systems for railway trains and parmaterial amounts. ticularly to those systems which use high ire- The present arrangement used is the shunting quency electric currents located largely in the of signal block joints with high frequency byrails forming the tracks. In this type of system passes, one type of which is the connection of the it is usual to employ coils carried at each end of two rails of each of two adjoining sections by a the train and inductively coupled with the rails. resistance or capacity or both and then connect- One set of coils (one per rail) functions as a ing the mid-point of each of these cross consource of electromctive force in the rails and the nections together.

l coils at the other end of the train function as With such an installation each track is elec- 10 receiving coils. These functions of the coils may trically a continuous path for communication reversed or two sets of coils, one as a transcurrents without cross connections between mitter and the other as a receiver, may be used tracks except such as may incidentally occur by at each end of the train. reason of track cross-overs. Leakage of com- 5 The electromotive force produced in the rail munication current from the energized track is beneath the transmitter coils produces current offered a relatively low impedance path in the flow therein to points remote therefrom in paths associated paralleling tracks of a multiple track depending upon the admittance of the various railroad if such tracks have their signal block paths. It is desirable to cause the greatest joints by-passed. The usefulness of the current 2g) feasible proportion of the total current fiow toleaking from the energized track at points lying pass the receiving coils in the rails beneath such between the transmitting and receiving points coils. If the equipment is operating on a multi-' is practically lost. Experience has shown that in ple track railroad it is also desirable that the the case of a four-track railroad with one of the current flow after passing beneath the receiving four tracks energized the current volume may be coils should be as widely diffused as possible so maximum in any one of the four tracks at 25 that the part of the total current flow appearing distances from the transmitting end equivalent in an individual associated track which is not to a long train length. This division of the directly energized will be suiiiciently small that it current in combination with the attenuation due will not operate other communication equipment to other causes may result in inadequate signal on adjoining tracks; otherwise there will be some strength at the receiving point. 30 interference between two equipments simul- My invention has particular application to a taneously functioning in close proximity even railroad having two or more parallel tracks, one when on different tracks. or more of which is electrically sectionalizedat A low impedance of the total loop circuit is intervals by insulated block joints and the simple desirable in order to produce an operative condiintroduction of my invention into the existing 35 tion with the limited electromotive forces availwayside signal equipment is an important deable in such types of equipment. sideratum.

In a railroad using a wayside signal system it To sum up, the principal objects of my invenis usual to: segregate a track into signal sections, tion are: (1) to provide a means for lowering each section being electrically insulated from adthe electrical impedance of the total transmis- 40 jacent sections by the insertion in the track of sion' circuit of an end-to-end communication insulating members commonly called block joints. system for trains using the rails as a part of the These block joints form insulating elements for transmission circuit; (2) to provide a means of the wayside signal currents and materially reincreasing the proportion of total currentflow duce the efficiency of the track as a transmitting in the track beneath the receiver point; (3) to 45 circuit for end-to-end communication systems provide a means of dispersion of the current flow on trains. after it has passed beneath the receiver coils, as-

The installation of an end-to-end communicasociated on the same train with the transmitting tion system using the rails as a part of the coils; (4). to provide such means for easy concommunication circuit therefor usually requires nection into the wayside signal equipment in 50 the installation of high frequency by-passes order that the latter may incidentally actuate the around these block joints. These by-passes are former; ('5) to providea simple and easy installaso designed that they will readily pass the high tion means of accomplishing the above objects frequency'currents of the communication sys which will progress with the train along the .55 tern, but will not allow the passage of the relatracks.

Still other objects and advantages of my invention will become apparent from the following detailed description of certain preferred embodiments thereof, reference being had to the accompanying drawings.

Fig. I is a diagrammatic drawing showing my invention installed in a pair of tracks contemplating the use of wayside signalling apparatus and its associated block joints, and the use of end-to-end communication systems on only one of the tracks.

Fig. II is a diagrammatic drawing showing the installation of my invention in a four-track system, contemplating the presence of trains .having end-to-end communication systems on only the two outside tracks.

Fig. III is a diagrammatic drawing showing my invention installed in a pair of tracks both of which contemplate the presence of trains thereon having end-to-end communication systems.

Fig. IV is a diagrammatic drawing showing a variation of the device of Fig. III in which the buses of Fig, I are added.

Before undertaking a detailed description of my invention as shown on the drawings it should be understood that railroad tracks as normally maintained are only partially insulated from earth and that if a track is energized with reference to earth or another point on the track, current leakages from and/or to the track takes place depending upon the conditions involved.

The degree of control of the amount and location of these leakages will largely determine the efllciency of use of the tracks as an electrical transmission path for communication purposes. With several tracks paralleling one another and each track segregated into partially insulated sections for wayside signal use it is possible to arrange these sections of multiple tracks into networks of such form as to produce circuits for transmission of communication currents in the tracks more emoiently than if no such arrangement was made.

In arranging the networks, use is made of buses interconnecting multiple tracks which are opened or closed by switches actuated by the wayside signal circuits, in accordance with the location of trains on the tracks. Use is made of signal block joint high frequency by-passes to produce electrically continuous tracks for the main transmission as well as to render available the characteristic impedance of the track earth circuit.

Where the leakage is abnormally high consequent of a very low characteristic impedance of the track earth circuit, it is desirable to reduce leakages as far as possible by the network arrangement.

. In Fig. I there is shown a multiple track railroad consisting of two tracks I and 2. Track I is made up of sections electrically insulated from one another by signal block joints 3 as is common practice. At each block joint 3 there is provided a high frequency electric current bypass 4 of the type referred to above, connecting to both rails of the track in each of the joined sections which is also common practice. The shown by-pass 4 has a resistance 8 at each end connected to the two rails of a track section, the resistances 8. being connected together at their midpoint as shown by wire 9. Each bypass 4 is then bused to a corresponding point in track 2 by a bus circuit or connection 5 made up of wires 5a and 5b and the bus circuit 5 is opened and closed by switch 6 which is operated by the relay I. Each relay 7 is connected to the two rails of the track I in an insulated section so that the presence of a train in that section will operate its relay I to open the switch 6 only during the presence of a train in the section. Because the presence of a train in a section operates the switch 6 to disconnect the bus 5 associated with that section, the inoperative bus 5 does not shunt ofi communication current as the train passes the bus 5. If the bus 5 were not rendered inoperative as a bus while intermediate the ends of a passing train, it would shunt oif the communication current and weaken the received signal communication current. Each relay is energized by a source of power I2 connected to each track section. The relay 1 may be replaced by the same relays which operate the wayside signal equipment now in use, as the wayside signal relays are similarly actuated by the presence of the train in the signal section. It is but a simple matter to adapt the signal relays to open the switches 6 at the same time the wayside signals are actuated by these signal relays, and close the switches 6 when the train leaves the signal sections appertaining to the switches 6. This easy connection into the wayside signal equipment is one of the advantages of my invention.

To explain the operation of this novel installation, it will be assumed that a train I!) is completely in a signal section of track I as shown. The train Ii] is equipped with an end-to-end communication system of a type using inductive coupling with the rails on which the train I0 is operating and using the said rails as a part of the communication current transmission path.

With no train in the signal section, relay I holds switch 6 in a closed position and completes the interconnection of by-pass 4 to track 2, Relay I permits gravity to open switch 6 whenever a train I!) occupies the wayside signal section forward of the location of relay I. Opening switch 6 opens the interconnection between tracks I and 2. The communication current network consists of a series of bussing connections between tracks I and 2, forward of, and rearward from, train II]; with the bussing connection between tracks I and 2 in the vicinity of the train Hi opened by switch 6. The switch 5 remains open until the train I0 has passed from the signal section with which the particular switch 6 is associated.

The communication current transmission may be considered as made up of several paths, among which are:

A path consisting of the energized track I, made continuous by by-passes 4, to the first-closed bus point forward and rearward of the train position, with the bussing connection 5a through switch 6 and connection 5b, together with track 2 forming the completion of a full metallic loop circuit. This path may be traced as follows: start from a point in the rails I adjacent the transmitting inductor in train I9 and proceed to the rearward from the train ID, through the rails of track I, through resistance 8, wire 9, resistance 8, rails I, to the next resistance 8, wire 9, wires 5a and 5b of bussing connection 5, rails of track 2, wires 51) and 5a of bussing connection 5 ahead of train I0, wire 9, resistance 8 and back to rails I beneath the train ID thus completing a metallic loop circuit.

A second path, consisting of track I to the bused points forward and rearward of the train I0,

feeding into the entire characteristic impedance of the rail-earth circuit formed by two extended tracks I and 2 bused together at a plurality of points and the return loop formed by earth.

These two components of the total path function as one circuit producing a low impedance in the total circuit, a higher current concentration at the receiver point, a division of current after passing the receiver point and a dispersion of the portion of current flowing into the characteristic impedance of the rail-earth circuit forward and rearward of the train position.

It is to be noted that there is no metallic shunting circuit formed by an interconnection between tracks I and 2 intermediate of the train ends; also that a conductor such as a wire or cable might be substituted for track 2.

These conditions progress along the track with train movement along track I.

In Fig. II my invention is installed in a fourtrack railroad system in which the outside tracks 2Iand 22 are for freight use having end-to-end communication equipment of the above described type and the inside tracks 22 and 23 are for passenger trains without such communication equipment.

This installation is but a more elaborate form of the one shown in Fig. I and operates in the same manner. Tracks 2! and 24 correspond to track I of Fig. I, and tracks 22 and 23 to track 2 of Fig. I. It is apparent that the operation of relays I and switches 6 on tracks 2| and 24 is the same as in the device of Fig. I.

The communication current transmission may be considered as made up of several paths, among which are: A path consisting of the energized track 22, made continuous by by-passes 4, to the first-closed bus point forward and rearward of the train position, with the wires Ila and Nb of bussing connection II through switch 6, together with tracks 2t, 22 and 23 forming the completion of a full metallic loop circuit.

A second path, consisting of track 24 to the bused points forward and rearward of the train III, feeding into the entire characteristic impedance of the rail-earth circuit formed by four extended tracks 2|, 22, 23, and 24 bused together at a plurality of points and in parallel therewith a,

leakage section of these same tracks lying rearward and forward of the fully bused points with the return loop formed by earth. These two components of the total path functioning as one circuit produce a low impedance in the total circuit, a higher current concentration at thereceiver point, a division of current after passing the receiver point and a dispersion of the portion of current flowing into the characteristic impedance of the rail-earth circuit forward and rearward of the train position.

The path of the induced communication current will flow as follows: start from a point in the rails 24 adjacent the transmitting inductor in train I I], and proceed to the rearward from train III, through resistance 8, wire 9, resistance 8, rails 24, resistance 8, wire 9, wires I la and III) of bussing connection I I, wires 9 and resistances 8 of rails 23, 22, and 2t, now toward train IE! through rails 23, 22, and 2! made continuous by by-passes' l composed of resistances 8 and wires 9, to wires Ila and lib of bussing connection II ahead of train Iii, through bussing connection II to wire 9 and resistance 3 of rails 24, through rails 24 under train It and back to starting point thus completing a full metallic circuit. In further detail the inside tracks 22 and 23 are permanently bused together and into the high frequency by-passes of tracks 2I and 24 by wires II a and lib forming connection II through switches 6 operated by relays I. Buses I I correspond to buses 5 ofFig. I.

With a train Ill occupying track 24, switch '5 is opened by relay I associated with track 24 and this track 24 is separated from tracks 2 I, 22 and 23 at points intermediate of the train ends and remains separated until the train II) leaves the signal section, at which time relay I closes switch 5 and a new bussing point is formed at the rear of the train I0.

Assuming a train It} on track 24 the return metallic loop for end-to-end communication current lying in track 24 is divided into three paths formed by tracks 2i, 22 and 23, and this path is in multiple with a return path formed by the entire characteristic impedance of the rail-earth circuit formedby four tracks multipled together extending forward and rearward of the train position.

These conditions progress with train movement along track 24. A similar description applies to track 2|.

In Fig. III a modified form of my invention is shown installed in a two-track system, in which the presence of a train Ill, equipped with end-toend communication equipment on track 32, is shown. Operation of end-to-end communication on tracks 3| and 32 is contemplated.

This installation contemplates the case where both of the tracks 3| and 32 are divided into wayside signal sections insulated frem one another by insulating block joints and further contemplates that the insulation from earth of one or both of the tracks is less than normally occurring.

Between the rails at each end of each wayside signal section is connected at high frequency bypass l sirnilar to those previously described in Figs. I and II as by-passes 4 except that wire I9 (made up of wires IQa and I313) of by-pass I 4 is broken by a switch I6 which is operated by a relay I! connected to the track adjacent the one with which the by-pass I4 is associated. Thus each by-pass I4 of track 3| is opened and closed under the control of a relay II connected to track 32. A train Ii] in a section of track 32 will by shuntingpower source I2 open by-pass I4 associated with the corresponding section of track 3i. In this way, there is a reduction of the shunting effect of track 3 I over the train length which arises out of the abnormally high leakage from the track energized for end-to-end communication currents.

As train I0 progresses along the track 32 the by-passes I4 between corresponding wayside signal sections of track 3| are progressively opened and again closed.

Fig. III contemplates the use of end-to-end communication on two tracks associated with one another, which have an abnormally low leakage resistance to earth.

If, in any case, the main portion of the communication current remains in the rails of the energized track until after it passes beneath the receiver coils, leakage in and beyond this point is very advantageous, but if such leakage takes place prior to reaching the receiver point, that is within the train length, such leakage reduces the strength of the received signal.

An actual connection from the energized track, intermediate of the train length, to a metallic path which would serve as a return path has a similar effect toleakage in this area and results in a reduced strength of received signal. Re-

moval of such connection or the provision of high impedance in them is highly desirable.

In this case, with each track made continuous by high frequency by-passes and one track energized, the other track acts as a metallic return path for such current as may leak onto it after leaving the energized track. This effect of the shunting action of the track associated with the energized track may be unimportant or very detrimental, in the latter case such effect may be reduced by opening the metallic continuity of the associated track.

The circuit of Fig. III is energized by apparatus on train I operating on track 32 made electrically continuous by high frequency by-passes 8, loop circuit I9 and switch i6 around the signal block joints 3. Switch I6 is operated by relay II, the latter being associated with the associated track, in this case relay II of track 32 controlling the loop circuit 9 connected to the high frequency Icy-pass 8 in track BI and vice versa. Relay II is controlled by the presence of a train in the wayside signal section with which relay II is associated.

With track 32 energized by equipment on train it the current flow is along track 32 into the characteristic impedance of the track earth circuit forward and rearward of the energized point with the return path in earth. The characteristic impedance is that of a single track; as there is no bus connection between tracks. A portion of the earth current leaks onto track 3| which portion of current is reduced by opening the metallic continuity of track SI at points intermediate of the length of and behind train I 9. By opening the by-pass It in associated track 3| the admittance of the metallic shunt path coextensive with the train length is reduced and a fuller utilization is made or the extremely low characteristic impedance of the rail-earth circuit composed of the multipled track network formed forward and rearward of the train position. Obviously other tracks could be connected in to the system in the same manner.

Fig. IV contemplates the use of end-to-end communication on two tracks associated with one another, which have an abnormally low leakage resistance to earth. The arrangement of track network is such as to make the train occupied track continuous by the use of high frequency by-passes around the wayside signal block joints; to provide an opening in the metallic continuity of the track associated with the train occupied track in the section opposite and/or behind the train position; to use-the characteristic impedance of the track earth circuit of all tracks forward of and behind the first point when both tracks are bused together to produce a lower leakage resistance to earth outside the train occupied section and to separate the energized track from other tracks--to preclude the direct metallic path interchange of communication current between tracks intermediate the train length.

This figure is similar to Fig. III except that an interconnection between tracks is provided, to function in accordance with the objects above delineated.

This diagram could be applied to tracks of Fig. II by making obvious changes in the connections. The circuit path of Fig. IV consists of an energized point on track 32 by apparatus carried by train I0. Track 32 is made electrically continuous, around wayside signal block joints 3 by high frequency by-passes 8, loop circuit I9 and switch I 6 when the latter is in a closed position. Switch I6 is actuated by relay I'I operated by the wayside signal circuit of track 3|. Forward of train IE1 switches I6 are closed thus providing a continuous forward path along track 32 and 3|.

In the rear of the train the first switch I6 of track 32 is open due to train presence and wayside signal circuit thus opening the Icy-pass 8 of track 3| but by-pass 8 of track 32 is closed through switch It of track 3|. The next signal location further to the rear of the train is a duplicate of that existing forward of the train. This much of the circuit has provided electrical continuity of track 32 and of track 3| except for the single opening of track 3i intermediate or behind train I0.

It is desired to bus the tracks together ahead of and to the rear of the train but not intermediate of the train. Use is made of part of loop circuit I9 with an additional connection and switch I8 actuated by relay I1 and a bus connection I5 which connects switch I8 associated with one track with switch I8 associated with the other track.

Current flowing forward along track 32 arriving at by-pass 3 flows to loop I9 at its point of attachment to the. by-pass, along I9 to switches I6 and I8 operated by relay I! of track 3|, through switch I8 to bus connection I5 thence to switch 28 of track 32 and thence to the forward side of by-pass 8 of track 3|. From loop I9 current also flows to switch I6 of track 3! thence through I9 to the forward side of Icy-pass 8 of track 32. The two tracks are now bused together forward of the train as well as made continuous.

Intermediate of the train length and/or to its rear, track 3I is opened; track 32 is continuous. The circuit at this latter location is identical with that previously described except that due to the presence of the train forward of this location relay I1 is functional to open switches I6 and I8 associated with track 32. The open position of switch It opens the connection from one side to the other of by-pass 8 of track 3I which was formed by loop I9, closed through switch I6. The closed position of switch i6 associated with track 3i together with loop I9 provides electrical continuity of track 32 past this point. The opening of either switch I8 (tracks 3! or 32) opens the bus connection I5 and separates the two tracks at this location.

By these means a larger proportion of current flow originating at the transmission point is passed beneath the receiver point in the rails of the energized track. My invention therefore considerably improves the operating efliciency of end-to-end communication systems and the simplicity and ease of installation, particularly in connection with existing wayside signal apparatus, is also an advance in the art.

While I have described the specific embodiments of my invention in detail above, it is obvious to one skilled in the art that a number of variations may be made without departing from the spirit of my invention as hereinafter claimed.

Having thus described my invention, I claim:

1. In a communication system, a railway track divided into signal sections by block joints of wayside signal equipment, high frequency bypasses around said block joints, a conductor in the vicinity of said track, a bus circuit connectmg each said track section to said conductor, and means for automatically and temporarily opening each bus circuit as a train enters the section associated therewith and closing said circuit as the train leaves said section.

2. In a communication system a pair of railway tracks, one of which is divided into signal sections by block joints of wayside signal equipment, high frequency by-passes around said block joints, a bus circuit connecting each said track section to the other track, and means for automatically and temporarily opening each bus circuit as a train enters the section associated therewith and closing said circuit as the train leaves said section.

3. In a communication system a plurality of railway tracks, buses connecting said tracks at spaced intervals, and means for automatically opening buses at any train occupied section of track and closing said buses behind said train as it progresses along the track whereby none of said buses is operative while intermediate the ends of a passing train.

4. An apparatus according to claim 1 charac terized further by the fact that said means for automatically opening and closing said bus circuits are relays connected to the rails of said track sections.

5. In a communication system, a pair of railway tracks, each being divided into signal sections by block joints of the wayside signal equipment, by-passes around said joints, said bypasses having sufficiently low impedance to pass the high frequency electric current of an end-toend communication system of trains and sufficiently high impedance to limit the passage of current of the wayside signal system to immaterial amounts, buses connecting the corresponding by-passes of each track, means for temporarily opening said lay-passes of one of said tracks, and means for disconnecting each said bus from the other of said tracks when a train is present in the section associated therewith and opening at the same time the corresponding bypass in the other track.

6. In a communication system, a plurality of railway tracks, each being divided into signal sections by block joints of wayside signal equipment, by-passes around said joints of such impedance that the high frequency current used in end-to-end communication systems on trains will flow but the lower frequency currents of the wayside equipment will not flow therethrough in material amounts, buses connecting the rails of corresponding sections of said tracks, and means for disconnecting each said bus from a train occupied section and opening at the same time one of said by-passes of each section of track corresponding to the occupied track section.

7. In a communication system, a railway track divided into signal sections by block joints of wayside signal equipment, high frequency bypasses around said block joints, a second railway track in the vicinity of said first track, a bus circuit connecting each said by-passes to said second track, a switch in each said bus circuit, and a relay for operating each said switch, said relay being connected to the rails of the signal section associated with the switch, whereby said switch is opened during the presence of a train in said section and closed when no train is present therein.

8. In a communication system, a pair of railway tracks divided into signal sections by block joints of wayside signal equipment, high frequency by-passes around said block joints, bus circuits connecting the corresponding sections of the tracks, normally closed switches in said bus sections, relays for operating said switches to the open position by and during the presence of a train in the signal sections associated with the switches, switches in said by-passes, and relays for opening said last mentioned switches by and during the presence of a train in sections of the other track in the vicinity of the by-pass switch.

9. In a communication system, a plurality of railway tracks divided into signal sections by block joints of wayside signal equipment, high frequency by-passes around said block joints, bus circuits connecting corresponding by-passes, a normally closed switch in each by-pass for disconnecting the sections of one of said tracks from the bus circuit, normally closed switches in the by-passes of the other tracks, and a relay for opening each of said first mentioned switches by and during the presence of a train in the section associated therewith and at the same time opening and closing the second mentioned switches in the sections corresponding to sections associated with the first mentioned switches.

10. In a communication system, a plurality of railway tracks divided into signal sections by block joints of wayside signal equipment, high frequency electrical by-passes around each said block joints, bus circuits connecting corresponding by-passes to form a metallic network of tracks with multiple branches having distributed leakage to earth, and means for automatically disconnecting said bus circuits from a train occupied section of track thereby forming said train occupied area in said network of tracks into; an area of high leakage resistance to earth in comparison to the surrounding network.

11. In a communication system, a plurality of railway tracks divided into signal sections by block joints of wayside signal equipment, high frequency electrical by-passes around each said block joints, bus circuits connecting corresponding by-passes to form a metallic network of interconnected tracks with multiple branches having distributed leakage to earth, and means for automatically disconnecting said bus circuits from train occupied sections so that at all times there is ahead of and behind the train position two networks of track connected together by a metallic conductor.

12. In a communication system, a plurality of railway tracks divided into signal sections by block joints of wayside signal equipment, high frequency electrical by-passes around each said block joints, and bus circuits connecting corresponding lay-passes to form a metallic network of interconnected tracks with multiple branches having distributed leakage to earth ahead of and behind the train position, said track network being progressively formed into two networks connected together by a metallic conductor and this metallic conductor energized between the two networks for the electrical transmission of communication signals.

13. In a communication system, a plurality of railway tracks divided into signal sections by block joints of wayside signal equipment, high frequency electrical by-passes around each said block joints, bus circuits connecting corresponding by-passes to form a metallic network with multiple branches and means for breaking said network into two joined sections of network having distributed leakage to earth ahead of and behind the train position as the train progresses, said two sections being connected together by a metallic conductor for use as an integral part of the electrical transmission circuitfor end-toend communication for trains.

14. In a communication system, a plurality of railway tracks divided into signal sections by block joints of wayside signal equipment, high frequency by-passes around each said block joints, bus circuits connecting corresponding bypasses to form a metallicnetwork with multiple branches and means for breaking said network into two joined sections having distributed leakage to earth ahead of and behind the train position as the train progresses, said sections of network being connected together by a metallic conductor for use as an integral part of the electrical transmission circuit for end-to-end communication for trains and a full metallic return path in multiple with the track-earth return path between saidtwo joined sections of said network. 151 The invention of claim 5 characterized further by the fact that a plurality of additional tracks are connected to said buses.

16. In a communication system, a pair of railway tracks separated into insulated sections, high frequency by-passes bridging said insulation, switches in said'by-passes, relays connected to each said sections in each track for controlling the switchesof by-passes of corresponding sections of the other track, and power source for operating said relays.

1'7. In a communication system, a pair of railway tracks separated into signal blocks, high frequency by-passes bridging the insulated joints, switches in said by-passes, relays controlling said switches, each said relay being connected to a difierent track from the one to which its associated switch is connected, whereby the presence of a train on one track opens the by-passes of the other track progressively, and a source of power for operating said relays.

18. In a communication system, a plurality of associated railway tracks separated into Wayside signal sections, means for connecting and disconnecting said track sections for electrically transmitted communication signals to form two connected networks having distributed leakage to earth; said connection between the two networks being the track occupied by a train progressively, and electrical means for transmitting communication signals through said train occupied section of track from one of said networks to the other and electrical means for receiving said communication signals.

19. In a communication system, a plurality of associated railway tracks separated into wayside signal sections, and means for connecting and disconnecting said wayside signal sections for electrically transmitted communication signals to form a loop circuit included in which are the signal section interconnecting means, the rails forming the energized track and the associated tracks, such loop circuit being at least coextensive with the location of the transmitting and receiver points.

20. In a communication system, a plurality of associated railway tracks separated into wayside signal sections, means for connecting and -dis connecting said wayside signal sections for electrical transmitted communication signals to form a loop circuit consisting of the energized track, the associated tracks, and the signal section interconnecting means together with two connected networks having distributed leakage to earth, said connection between the two networks being the energized track; said loop circuit and said distributed leakage circuit being in parallel with one another and means for transmitting and receiving said communication signals through said circuits, both of said circuits progressing in steps concurrently with train movement along the track.

SYLVESTER M. VIELE.

DISCLAIMER 2,095,621.Sylvester M. Viele, Swarthmore, Pa. END-TQ-END COMMUNICATION SYSTEM FOR RAILWAY TRAINS. Patent dated October 12, 1937. Disclaimer filed June 22, 1940, by the inventor. Hereby enters this disclaimer to claims 1 and 4 of said Letters Patent.

[Ofiic'ial Gazette July 16, 1940.]

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