US2052581A - Train traffic control - Google Patents

Description

Sept. 1, 1936.. H. w. RICHARDS 2,052,581

A TRAIN TRAFFIC CONTROL Filed May '7, 1932 2 Sheets-Sheet 1 v Sept-l, 1936. H. w. RICHARDS 2,052,531

v TRAlN TRAFFIC' CONTROL Filed May 7, 1932 2 Sheets-Sheet` 2 s l N 4 N Q z It f5 V) u; INVENTOR:

t; RRY WI Rzcmqkns N2 By :dz-Tommy Patented Sept. 1, 1936 p UNITED .STATESY PATENT Vol-FICE 2,052,581 TRAIN 'mismo CONTROL y Harry W. Richards, Kew Gardens, N. Y. Application May 7, 1932, Serial No. 609,940 11 claims. (Crais- 3) 'I-'his invention relates to train dispatching systems and more particularly to the control, from a central point, of the signals,- switches, etc. of the entire system, wherefore this invention ls directed to a centralized trame control. This con- Another object of the invention is to provideA a line current which will .operate through the entire plurality of. wayside stations whereby similar apparatus at these stations will be similarly affected by being tuned to the particular frequency of the line current at that time, and which frequency is selected in accordance with the desired vcontrol of vthe taic.

A further object of this invention is to provide a normally closed line circuit by which the progress of trains, commonlycalled OS indications, may be indicated at the dispatchers omce.

Referring to the'accompanying drawings forming a part of this specification and in which like legends indicate like parts in all the views:- K Fig. 1 is a wiring diagram of a portion of a system to which this invention has been applied but in which only one wayside orcontrol station is illustrated; and

Fig. 2 is a wiring diagram of the selecting relaysv transformer are connected on one side; 'in parallel relation, with the line wire l which constitutes the common vreturn of currents supplied to the waysidestations. The other sides of said secondaries arje connected to relays at said wayside stations by the closing o f a contact i. n the dispatchers office. Through a contacting device inthe dispatchersv oice the circuit will be completed from one or more of.. said transformers to the Vvv'ire 2 forming the other side of the line circuit.

The contacting device maybe inthelform of a distributor soconstructedj-that its constantly rotating member 3may nialrejconsec'utive contact -with 'segments for closingthe'circuit ofone orM more transformers singly or in combination, and to control operation of relays A, B, and C at the wayside station. Further, said rotating member is permanently connected with a wire -4 connected in parallel to one end ofa plurality of 5 tuned circuits identiiied respectively as OS', C', B', A', 5, 6, .'l, 8 and MC', the other end of said circuits being connected in parallel by the common wire 9.' The wire 4 is continued to the point lll which point is located on the wire Il whose 10 opposite ends are connected to one side .of the secondaries of. the transformers fOS and IMC.

Here it should be stated that the above mentioned tuned circuits are tuned to form path's of low impedance for the frequencies respectively of 15 the transformers IOS, fC, fB, fA, f5, f6, f'l, f8 and fMC. The tuned circuit OS includes a relay OS, and the tuned circuit MC includes a relay MC. The relay OS has an armature l5 connected as by the wire 'I6 to the aforementioned wire Il, 2o

vthe back contact 4of said relay being connected as by the wire I'l tol any suitable source o1' current .I at for the purpose of. simplicity in the drawings this wire il has been shown connected to the positive side of /a battery.

In the dispatchers office on a suitable panel i8 there is/mounted a'pair of keys similar to those `used in .telephone switchboards and by which contacts are made yand broken by the movement of pivoted levers such as the switch con- 30 trolling lever I9 andthe signal controlling lever 20, these levers having three positions, up, down. and center at which they will stay when moved manually thereto. The switch lever I9 controls contacts 2|, 22, 23 and 24 and the signal lever 2li 35 controls similar contacts 25, 26, 2'! and 28, said contacts so arranged that when the levers are in the central position, as shown, the contacts 2|, 24, 25 and 28 will be closed; when an upward movement is given to said levers then contacts ,40

2| and 25 will Vbe opened while at thesame time contacts 22 and 26 will be closed; and when a downward movement is given to said levers then the contact `2li; one side of the secondary of `Vthe transformer jl is connected as by the Swire 3l to one side of the contact 21; one side of the sec- 5o ondaryof the transformer f6 is connected as byj j the wire- 32 to one side vofj` the contactV 22;- and Y one side-of the secondary 'of the;1:1-ansifm-mi-A frff is connected as byh the wire 33 to oner side ofthe contact 2s. l"nie gthersidespr auteure ieve.,

contacts just mentioned are-connected to a seg- Ament of said distributor by the common wire 34.

The distributor has a constantly rotating arm or finger 3 the end'of which successively passes over a plurality of arcuate segments each of which is adapted to be connected in one or more circuits, said segments being arranged in paths concentrically disposed about the axis of the distributor arm. The outer circular path in the drawings is composed of a series of sixl segments generally indicated by the numeral 5l, there being one segment for each of the sixwayside stations intended to be controlled, but it is to be understood that this number of six will be increased or diminished according to thev number of said wayside stations and is always the'same as the total number ofl said stations. Therefore,

in this particular exemplificatiom the distributorhas six active sections, one for each wayside station, and these sections have been identified in Fig. v1 by the heavy numerals I, 2, 3, 4, 5 and 6.

The segment 5I in the outer path of the distributor for controlling wayside station No. 1 is shown connected to the wire 34 from the contacts of the control levers. The next adjacent segment in the outer circular path. and associated with the section for controlling operations at Wayside station No. 2 Will be connected by a wire 52 similar to the Wire 34 but leading to contacts of a duplicate set of levers for controlling current to wayside station No. 2; in a similar manner the next segment in the outer circular path of saidv d istributor and in the successive sections or station groups 3, 4, 5 and 6 will be each connected by a Wire similar to said Wire 34 to additional pairs of levers which will respectively control current to wayside stations Nos. 3, 4, 5 and 6. Thus it will be seen that the segments of this outer circular path are each individuallyconnected tof'the contacts of the respective wayside station control levers.

The reiay Moin the tuned circuit Mc' has an' 28 serially connected, and thence the current will pass over the wire 38 to and through the relay PC back to source. v 'Ihe opening of any one of the contacts 2|, 24, 25 or28 by the up or dowmovement of either or both of the control levers I9 or which latter will cause its armature 35 to drop.4

Relay PC will in'like manner be dei-energized by the openirrg of similar contacts associated with the control levers for stations 2, 3, 4, etc. (not shown), all such contacts being serially connected and in circuit with the coils of relay PC.

The relay PC lis normally energized so that its triple armatures 39, 40 and 4 I will be held out of contact with their back contacts, which latter are respectively connected as by the wires 42, 43 and 44 with one side of the secondaries of the transformers fC, fB, and fA. As relay PC controls the iiow of current of all station selecting frequencies to the, distributor contact segments, the number ber of wayside stations, anarmature being provided for the control of suchV frequency. The

armature 39 is permanently' connected to the wire 45 so that current may at times flow thereover to energize a series of connected segments. generally indicated by the numeral 46; arranged in'a circular' path on said distributor and adapted to be contacted by its -rotating arm 3. In alike manner the armature 40 is permanently connected to the Wire 41 so that current may at' times flow thereover to energize another series of connected segments, generally indicated by theergize still `another series of` connected segments,

generally indicated by the numeral 50, arranged in a circular path on said distributor and adapted to be contacted by its arm. However, it should here be stated that the combination of the Segments in any one station group on the distributor isdiierent from the combination of segments in any of the remaining station groups.

This is done deliberately for two purposes, vi'irst to make possible the selection of a particular wayside station and, second, to control the operation of the desired switches, signals, etc. at that particular station. In Fig. 1 it' will therefore be seen that the distributor arm will contact successively with segments in the outer circular path, such as 5i, each adapted to select a wayside station, and while in contact with any segments 46, 48 and 50 in the' remaining circular paths, which combination will be different' from the combination of said last named segments found in any of theother distributor station control groups. Therefore, it will be appreciated that when the relay PC is deenergized its armatures will drop and cause current to flow from the transformers fC, IB, and fA to the circular 'series of segments 46, 48 and 50 of the distributor. *At

the dispatchers board and associated with the control lever panel I8 is an indication lamp 55 one side .of which isv connected to the wire 34 and the other side of which is connected to theinegative side of the battery or other source of current associated with the back contact of relay OS. Therefore, when relay 0S is deenergized and its armature l5drops, current will flow through wires I6 and 4 to andthrough the distributor arm 3, through segment 5I, and over the wire 34 and lamp 55 back to the source, illuminating said lamp. "The lamii``55 is associated with the control' levers I9 and 20 for waysidenstation No. 1 and another lamp is similarly connected to and asso- 'ciated with the distributor and the control levers of each ofthe remaining wayside stations, and anyone of these lamps will be illuminated upon deenergization of relay 0S at the time when the distributor arm is contacting with the segment such as 5I in the outer circular path and in the distributor section group to which that lamp is connected. l

Also, at the dispatchers office, but not necessarilymounted on the same board ornpanel with the control levers hereinbefore mentioned, is a track diagram wherein 'the'v spots suchas 56, 51 and 58 indicate insulated rail joints in the track;

the heavy lines .59' and 50 indicate straight sections ottrackrl indicates the switch section of said main' line; 62 indicates .the portion -of a the switch of the siding. As distinctly shown, the

line 63 is made vertical instead of oblique as heretofore customary in such diagrams in order -to save space on the indicating board, thereby making possible a considerable shortening of the indicating b oard and on which is amply shown the trackage condition of a long railway system'.

In Fig. 1 is shown station No. l which is one end of a passing siding at which is located a switch machine SM for moving the switch, as well as an entering signal Si and a take-siding signal S2, and in addition thereto the leaving signals S3 and S4. The rails are insulated as shown to provide a track circuit section including a battery 6d and the relay TR. While this figure shows only one wayside station it will be readily understood that this is only for the s'ake of brevity since the wiring diagram for this station No. l is practically duplicated for other wayside stations. Fig. 2 illustrates partial wiring diagrams Vfor three wayside stations, and is 'presented for the purpose of showing the only changes which 4occur in the wiring at said stations. Y

VReferring particularly to Fig. 1 current is taken o the main line at dierenti'requencies for operation of the several relays located at station No. 1 and for controlling the operation of signals, switches, etc. and from Fig. 2 it will be understood that at the remaining wayside stations there will be a similar take-'oil of current, all of the wayside stations being connected serially in the line circuit, wherefore impulses will occur 'simultaneously at all of said stations when the nance with the tuned circuits A', B' and C.

The wire 654 has an extension 61 and the wire t6 has an extension 68 across which extensions are parailelly connected tuned circuits 52, 62, 'i2

. and 32 which contain the control relays 5', 6',

l' and 8' respectively.,

, Each of the relays A, B, and C has an armature with front and back contacts, the armatures 69. lil and 1i of said respective relays being connected to a common wire 12 leading to any suit- -V able source of current which, in the drawings,

is shown as the positive. side of a battery. lSaid iront and back contacts are wired diierently for the different wayside stations, it being observed that at'station No. l the front' contact of relay A and theback contacts of relays B and C are not electrically connected in circuit. On

- the other hand. the back contact of relay A and the front contacts of relays B and Care connected inparallel for energizing `the transmitting. relay T.

With particular-reference to Fig. 2 mentioned construction and connections at sta-'- tion No. 1 are repeated but the connections vat stations Nos. 2 and 3 are somewhat'diierent. At all stations the station selecting relays A, B and C are connected in similar tuned circuits and are 4 provided with similar armatureabut thediii'erence lies inthe wiring of the, front fand back contacts thereof. That is to s ay, at station No. 2 the front contacts of relays Aand B and the the aforeback contact of relay C are not connected, `but vthe backv contacts of relays Avand B and the front contact of relay C are connected in parallel to energize the transmitting relay T. At station, No. 3 the back contacts of relays A and C as well as the front contact of relay B are uns connected, whereas the front contacts of relays A and C and the back contact of relay B are connected in parallel to energize the transmitting relay T.' Where additional wayside stations are to be controlled. further combinations of armature contact wiring are employed, and in this connection it will be understood that the number of segment control sections may be increased on the distributor with attendant change in R.'P. M. of the distributor arm, and the number of station selecting relays may be increased to suit the needs of the control system. Y

The transmitting relay T is normally energized and therefore attracts its doublearmature,

thereby closing the tuned circuit .OS2 which isl .parallelly connected across wires 65 and 66. On

the other hand, when relay T is deenergized its armatures will drop, thearmature 'I3 contacting the back contact and causing current to flow from any suitable source (indicated as a battery in Fig. 1) over the wire 14 through the armature l5 of a track relay 'IR thence over the wire 16 to the back contact of relay T, over the armature '13, thence over the wire 'i1 to the front contacts of all of the control relays 62,1', andI 8'. The armature 18 oi the relay 5' is connected in cir- 4 cuit to one end of the magnet coil 19, the other end'of which is connected to a source of current such as the aforementioned battery; ,and the armature 80 of the relay 6' is connected to one end of the magnet 8i the other end of which is connected to said battery.` Between the juxtaposed magnets 19 and 8| is an armature 8-2 adaptedito be attracted to whichever of said magnets is energized. If the armature be magnetized, then it will stick in the position to which it is movedv even after thev attracting magnet coil has become deenergized, and not be moved there-4 from until energization of the other magnet coil.

In a like manner the control relays 1' and 8' have respective armatures 83 and 84 connected in circuit with juxtaposed magnet coils 85 and 8B between which is an armature 81, all vhaving functions and operations similar to the corresponding parts last described.

The armature 82, in either of its positions, is adapted to make contacts controlling actuation of the switch machine SM, and the armature 81, in either of its positions, is adapted to make contact to control the operation of all of the signals.

Si, S2, S3 and SB at station No. 1 as indicated diagrammatically by the dotted lines in Fig. 1, and as should readily be understood.

The switch machine SM is adapted to actuate a switch circuit controller or contact `member in- 9D.throughwire 92to the front contact of relayTR.

`'armature 93, the wire 94, master control relay M, and thence back to battery. When a train 75 is in the limit of its opposite movement and conv enters the track vsection containing relay TR, said relay will be deenergized whereupon 'its' armatures will drop and break the circuit just described, thereby deenergizing master relay M.

This same open-ing of the circuit will occur should there be a faulty actuation of the switch byl which the contact member 9D does not assume its. -full thrown position in either direction. That lis to say, said member will close said circuit when in the "full limit of movement in one directionand contacting wires 9| and 92, or it will perform the same function of closing the circuit'when it tacting wires 95 and '96 which are connected in parallel `with Wires 9| and 92.

When relay M becomes deenergized,.its double armature will drop thereby opening the-'tuned circuit MC2 connected in parallel with the wires- 65 and 66.- The tuned circuit MC2 is a path of low Aimpedance for the current having the frequency of transformer -fMC, and master control relay M is in series with the tuned circuit MC'.

Therefore', the opening ofthecontacts of the master control relay- M will open the tuned circuit MC2 which in turn opens the path of low impedance for the current having the frequencies of vtransformer fMC, and as relay MC is lserially connected in the tuned circuit including MC'and MC2, the interruption to the flow of .current having the frequency of the transformer IMC will cause the openingof relay MC.

'I'heJ operation of the system is as follows.. A plurality of transformers is provided each having a frequency different from the frequency of any of the others. Should the dispatcher wish to operate-the'switch of station No. l to the reverse position (opposite to that shown) he will move the switch lever` I9 upward as indicatedby the `arrow and the letter R thereby opening contact 2| and closing contact 22.l Opening of contact 2| deenergizes relay PC permitting closing of the circuits from transformers fA, fB, and fC to and .of station No. 1 and the segment 50 controlling the circuit of relay A atall of the wayside stations, thereby attracting the armatures of said relays A against their front contacts and away from their back contacts. This attractiononly accomplishes results, however, at station No. -1 by virtue of the breaking of the battery circuit through transmitting relay T thereby deenergiz-A. ing the latter. 'The corresponding relays T at the remaining stations will not be deenergizedr because the batteryv circuit of sad relay is still maintained at stations Nos. 2 and 3 by the back contacts of relays B. The deenergization of relay T- at station No. 1 therefore completes the battery circuit through its armature 'I3 to the front contacts of the control relays 5', 6', 1' and- 8'.

Simultaneously with the operation of relays A and T, current having the frequency of. transformer f6 will ow from the contact segment 5| to and through the ,distributor arm 3, ,wire *4, the tuned circuit 6, wire 9, the line wire 2 through wires` IiIiV yand 68 to and through the tuned circuit 62 to energize the 4control relay 6' thereby attracting itsr .armature 80 and closing a circuit which energizes. magnet coil switch machine SM causing it to operate and,

the'switch Amachine is thus operated its contact member 90 moves from the position shown in Fig. 1 downwardly to ultimately come in contact move the switch to the4 reverse position. When with the wires 95 and 96, and in this movement 4 the circuit controlled by the member 90 is mo-- mentarily interrupted causing the deenergization -of' relay M, in turn breaking .the tuned circuit- MC2. This'causes relay MC to become deenergized and to cause the breaking of the circuit in- ;cluding relay PC which is thereby de-energized.

When the arm 3 of the distributor again moves around to contact the segments 50 and 5I vof station No. 1, current having the frequency of transformer fA will flow through said arm, wires 4, etc. .to energize relay A there by attracting its armature 69 and deenergizing relay T at station No. 1, the opening of the front contact of said last mentioned relay breaking the tuned circuit OS2 thereby interrupting the path of low impedance of current having the frequency of transformer fOS causing deenergization of relayOS and thedropping of its armature I5 to close a battery circuit over wire Il, armature I5, wire I6, wire 4, distributor arm 3, segment 5I, wire 34, through lamp 55, and thence back to battery. This will cause a momentary illumination of the lamp 55 indicating to'the dispatcher that theswitch is movingto the reverse position. r

Should the switch for any reason fail to complete its reverse movement then the switch convluminated whereas, inthe proper movement of the switch the movement of the member 90 is,`

relatively fast and thus only afmomentary lighting of the lamp'will result. After the proper.

momentary illumination of the lamp has occurred, the dispatcher will then be free to return the switch leverA I9 to the central position shown in Fig. 1 thereby completing the circuit and energizing relay PC, which then picks up its armatures and opens the circuits of the transformers fA, JB, and fC to the distributor, thereby cutting off from the line circuit the current frequencies of the transformers fA, fB and fC, and allowing the wayside station relays A, B and C to come to rest. Should the periodically continuous illumination of the lamp 55 occur, indicating an incomplete switch movement, the dispatcher is free to move the switch lever I9 downward as indicated by the arrow and letter N, thereby causing the switch' machine SM to operate the switch andl switch contact member 90 to the normal position, as hereinafter explained, so that the switch may .be used in thisl position until the trouble is rectied.v

On the contrary, if it is desired to move the switchV back to its normal position, then the dispatcher will throw the switch lever I9 down- Wardly in the direction indicatedr by the arrow and the letter N. This causes anbpening of contacts 24 and a closing of. contacts 23. 'Ihe opening of contacts 24 will break the circuit through the relay PC thereby deenergizing the same to complete the circuits containing the' frequencies of fA, IB. and fCY to the respective distributor segments 50, 48 and 46. The closing of contacts 23 completes a current circuit having the frequency of and including transformer f5, wire 34,

segment 5| and the arm 3 of the distributor,

wirev tuned circuit 5, wire 9, wire 2. wires 6B and 68, tuned circuiti2 energizing control relay 5' to attract its armature 18 and causing a closing of the circuit including the magnet coil 'i9 which attracts its armature l82 in the reverse manner against a contactina, circuit to and through the switch machine SM to operate the switch in the opposite direction. The remaining operations and actuations of relays are th'e same as just previously described and therefore need not be repeated, the lamp 55 again being momen-- tarily lighted when the switch contact member 90 moves properly and synchronously with the switch. Thus, when the dispatcher. gets his "S indication" through the light 55 he is then free to i move his switch lever back to the central position shown in Fig. 1. In this operation as well as Vthe operationin the precedingparagraph, it will, of course; be understood that the dispatcher is manually throwing the switch lever on the panel board I8 associated with station No. 1.

Should similar switch operations be desired, for example a+ station No. 2, the operations would be substantiallyy the same except the dispatcher would manipulate his switch lever on the panel board and associated with station No. 2 wherefore the operations hereinbefore described would not take place until the rotating arm 3 had come into registry with the combination of distributor segments in the section group controlling station No. 3. At this time said arm will be in contact witha segment 50 as will as a segment 48, the segment 50 controlling the current'having the frequency of' transformer fA and the segment 48 controlling the'current having 'the frequency of transformer fB, thereby causing the currents of these 'frequencies t`o flow in the line circuit to and 1 through the tuned circuits of relays A and 'B at all the stations. This attracts the armatures of both relays but at station No. 1 such attraction will still-cause its relay T to remain energized.

'At station No. 2 the movement of said armatures positively opens its relay T wherefore the hereinbefore described operations of switch changes will take place at station No,V 2. There will be' no I switch operation at station No. 3 because the movement of the armaturesof its relays A and B will retain its relay T energized.

In a similar manner should the dispatcher desire to throw the switch at station No. 3, he operates the switch lever associated with station No. 3 which causes the foregoing' circuit manipula- A tions to be eiective only when the distributor arm circuit 'including the signals SI., S2, Sl'or SQ,-

Vcornes into registry with the segments oi' station group 3, and when this occurs only the-segments 68 and 5i` will be contacted. The contacting of segment 48 controls the-current having the frequency of transformer fB and thus energizes the The' operation of the .trackside signals is carried out in a mannersimilar to the description given immediately hereinbeforewith respect to the operation of the switch', except that thevdispatcher will manipulatejshe signal lever 20 for the particular wayside station desired instead of the4 switch lever. This will bring about the functioning of control relays 1 and 8' at the selected wayside stationin accordance with the desired signal control, and the energization of these'relays will throw the armature 81 to close a' battery Like the armature 82, armature 81 may be permanently connected to a battery current to close the circuits of the switch machine and signals, respectively; or it may be merely a mechanical means to close spaced terminals of such circuits, and therefore be supplied with double pole contacting members, all as will be readily under- Stood.

With switches and signals' properly set the. .l

passage of a train over the track circuit including the battery 64 and relay TR causes the deenergization of said relay and the opening of circuitsincluding its armatures. That is to say, the opening of the circuit including armature 93 causes the deenergization of master relay M which in turn opens the tuned circuit MC2 and deenergizes MC and in turn relay PC, when the contact arm 3 engages the distributor segments 50 and 5I of station group 1, whereby the current having the frequency of transformer iA energizes relays A at all the stations. At station No. 1 the attraction of the armature 69 causes deenergization of relay T at said station thereby opening the tuned circuit OS2 and causing a deenergization of OS with consequent completion of battery circuit to and through the lamp 55,- thus ltelling the dispatcher that the train is passing the control station No. 1. When the train has passed out of said control section of the track then the relay TR is again energized by its battery 64, attracting its armatures and closing the circuit through master relay M which in turn at- -tracts its armatures and completes the tuned circuit MC2 causing relay MC in turn to be energized and pick up -its armature 35 and complete a battery circuit including the-relay PC which latter attracts its armatures and reestablishes the normal condition of the system for further control actuation. 4 v

It is obvious that thoseskilled in the art may vary the details of construction as well as arrangements of parts without departing from the spirit of the invention, and therefore it is not desired to be limited to the foregoing except as may be required by the claims.

tane'llsly With control CulTen frequencies'common to all stations.

' 2. In a train trailic control system the combination of a trackside signal and switch actuating mechanism; la main line circuit including selectively operated relays for. controlling said signal and said mechanism; a source of pulsating current of different current frequencies for said circuit: and manually and automatically operated means including a rotating distributor for selectfing a current of a particular frequency for operating the desired relay; and station selecting current frequencies impressed upon said line circuit in different prearranged combinations' simultaneously with control current frequencies common to all stations. 'y Y 3, In a train traflic control system the combination of a tracksidesignal and switch actuating mechanism; a main line circuit including selectively operated relaysA for controlling said signal and said mechanism; a source of pulsating current of different current frequencies for said circuit; and manually and automatically operated means for selecting a current of a particular frequency for operating the desired relay; and station selecting current frequencies impressed upon said line circuit in different prearranged combinations 'simultaneously with control current frequencies common to all stations- 4. In a train traffic control system the combination of a trackside signal and switch actuating mechanism; a main line circuit including selectively operated relays for 'controlling said signal and said mechanism; a source of pulsating current-of different current frequencies for said circuit; and means including a manually operable switch as well as an automatically rotating distributor for selecting a current of a particular frequency for operating the desired relay; and station selecting current frequencies impressed upon.

said line circuit in different prearranged combinations simultaneously' with control current fre-l quencies common to all stations. 1

5. In a train trailic control system the combination of a trackside signal and switch actuating mechanism; a. main line circuit including s'electively-operated relays for controlling said signal and said mechanism; a source of alternating current of different current frequencies for said circuit; and manually and automatically operated means for selecting a current of a particular frequency for operating the desired relay; and station selecting current frequencies impressed upon said line circuit in different prearranged combinations simultaneously with control current frequencies common to all stations.

6. In a train trafc control for a railway having a plurality of trackside signals the combination of a source of current of different current frequencies; a main line, circuit including relays res onsive to said currentl frequencies for contro ling said signals; Iand manually and automatically operated means for selecting a current frequency making responsive the relay for controlling the desired signal; and station'selecting current frequencies impressed upon said line circuit in different prearranged combinations simultaneously with control current frequenciescomi f mon to all stations.

7. In a train traflic control for a railway system having a plurality of wayside stations and including trackside signals the combination of a source of pulsating current having diierent frequencies; a distributor provided with a constantly rotating arm connected to said source, and a plurality of segments adapted to be contacted by said arm in its rotation, said segments arranged in concentric pathsV as well as in wayside station control groups, the segments of certain paths serially signals at saidqstations; and a plurality of relays at each station connected in said line circuit for controllingsignal actuating circuits, each relay tuned for resonance with one of said different current frequencies whereby the signals will be operated irl-accordance with the frequencies of the current flowing in the line circuit.

8. In a traiiic control system, a transmission rent frequencies upon said circuit; station selecting frequencies impressed in different prearranged combinations simultaneously with control frequencies common to all stations; a plurality of current paths arranged in parallel with respect to each other and each beingin series with` said transmission circuit, each path selective to a different one of said current frequencies; and a traiiic controlling device responsive to the flow of current in saidpaths.` l

9. In a traffic control system, a transmission circuit; means for impressing a plurality of current frequencies upon said circuit; a central office and a waysidestation the latter including a plurent frequencies upon said circuit; a central cnice and a wayside station, said central olce including a plurality of current paths arranged in parallel to each other and each beingin series `with respect to said transmission circuit, each path selective to a different one of said current fre-` quencies; and a normally energized trafic control indication means included in said selective paths.

11. In a trac control system, a transmission circuit; means for impressingV a plurality of current frequencies upon said circuit; station select-- ing relays included in said circuit; a normally energized control circuit adapted to maintain the circuit; means' for impressing a plurality of curstation selecting relays in yastate of rest; and

means for deenergizing said control circuit to cause actuation of one or more station selecting relays.

12. In a. tramo control s ystem, a transmission circuit; means for impressing a plurality of current frequencies upon said circuit; station selecting relays included in said circuit; a normally energized control circuit adapted to maintain the station selecting relays in a state of rest; and means for deenergiz'ing said control circuit to cause actuation of one or more station selecting relays in accordance with'one or more of said frequencies.

13. In a trafilc control system, a transmission circuit; means for impressing a plurality of current frequencies upon said circuit; station select- `quency combination.

14. In a trailic control system, in combination a transmission circuit; means for impressing a. plurality of current frequencies uporrsaid circuit: a central office; a wayside station; and a detector track circuit associated with said wayside station 7 5' alsA and including a relay adapted to be de-energized upon the passing of a train, said central oiiice including a normally energized traiiic indication device connected in circuit with contacts controlled by said relay at said wayside stationthe desired relay; and station selecting current frequencies impressed upon said line circuit simultaneously with a control current frequency common to all stations.

16. In a traiiic control system, a main line circuit, a source of pulsating current-of different current frequencies for said circuit; relays controlled from said line circuit and' responsive to current in circuits tuned1 for similarly different.

current frequencies; manually and automatically operated means for selecting current of a particular frequency for operating the desired relay; and station designating current. frequencies impressed upon said line circuit simultaneously with a control current frequency common to all sta.- tions.

17. In a traiilc control system, a main line circuit, a source of pulsating current of'diierent current frequencies for said circuit; relays controlled from said line circuit and responsive to current in circuitstuned for similarly different current frequencies; and station designating current frequencies impressed uponssaid line circuit simultaneously with a. control current frequency common to all stations.

HARRY W. RICHARDS?.

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