US2272106A

US2272106A - Transmitting apparatus for train communication systems

Info

Publication number: US2272106A
Application number: US374267A
Authority: US
Inventors: Philip P Ash
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1941-01-13
Filing date: 1941-01-13
Publication date: 1942-02-03
Anticipated expiration: 1959-02-03

Description

7 Feb. 3, 1942. I s 2,272,106

TRANSMITTING APPARATUS FOR TRAIN COMMUNICATION SYSTEMS F'il ed Jan. 13, 1941 Madahzor Amplz'fibr llazop 4 A. iz'zzalljzk'ell Inbound Yard Patented 3, 1942 -:{TRANSMITTINGAPPARATiiSEOR'TRA N' j a COMMUNICATIONJSYSTEMS v ramp. Ash, iijiiisviue, iKy',

' 'ApplicationJanuary 13, 19 411; Serial No.

OLE 46. 8) I .My invention relates .to "t ransmittiiigsappae ratus tori-train communicationsystems,iand' niore particularly to transmitting apparatus for communication'system's 'for'classification yards; Railway train communication systems :ordi narily use a carriercurrent; For'telep'hone com-L munication ;a carrier of a wpreselected "frequency is modulated "by the voice 'frequencies and :a selected sideband is transmittedfthenarriir and the other side. band being, ordinarily at least,

suppressed. 'In' such fa system a calling orsig naling current equivalent "to a the carrier 'niodulated by a preselected frequency withinthe voice frequency 'rangeis. employed. In railway cla'ssification "yards such communication 'systerris'are usedior directing; the movements ofshifting lo.- comotives from 'acentralzyard oflice,"and it has been proposed that the calling or signaling our U i sw ch-ant S lJQQmPg nYL Pa., a corporation fof Pennsylvania Jtion yard orirbetweeni I oflice: and the crews of all'the locomotives withinthe classificationyardg"a; v; x f Ii The above. features; of Emy invention; as well -as 1 tween the operator, atacentral oifice stati niand the screw of a locomotive operatin ,in either the inbound 'org in 'tlie outbound yard of acIaSSAflOa the operator; at the central other advantages whiohwill become apparent as a the specification ;progresse s-, are attained accordapparatus: ihavin in I0 my-=-invention l by j providingtransmitting a first j. manually operable sw tchin ,nieans at. one os t on o I w 1 th apparatusto rent be transmitted 'at all times except when.

telephonecommunic'ationis desired to provide a) a cab signal indication thattchecks "the operative condition of the apparatus; In classification yards where a humpis use'd,"a fixed wayside sigrial 'of the semaphore 'or I'color light type islo-; cated in the vicinity or the vhump "and is con trolled by the yard conductor to signal to the shifting 'Iocomotiv'the "spee'dand movements desired for thecars' that are being classi'fiedloy n being pushed over the "hump. Such a fixd'signal may not always be effective because of the g:-

limitedv visibility under bad weather conditions. Acc'ordingly'a feature of nay-invention is the the; ap aratus s re h of; t a k transmitting apparatus-is;conditioned to produce a d at; n thenp I tionj at 3 which the apparatus J is conditioned to a carrier signaling current produ e a car ie telephon c rren and e c of whic curr n s s ied @by h t m n .a ion pn E ri ui 1 uch out :c'i cuit *is, connected ;to*;a j transmitting circuit extend n a on -astret a a ed rorjc mm nicat n n, a jclassificationx a c twoermom transmitting G n cu ts i may-she neared-1.0 such ansmi t n circuit ma bex or examp s c d it o h-asthe tracks of the in-,

oundsa d a sec d rans itting circ i may be i asscciated withagsecond stretch of track such asjthe tracks"of-"the;outboundyard. When twotrans i s pi u tsl"are p o ided, th -butprovision of novel andimprovd transmitting apparatus for train communication systems-I Another ieature of my invention is the provision of novel andim'provedtransmitting appa ratus 'for train communication systems for 'classification yards. 7 a I I i Again, a 'feature or "my invention isthe'p'rovision of apparatus for train communication. sys'iterns 'fincorporating novel transmitting {means for supplying a carrier signaling current which -is..coded at differentcode rates whereby-"such coded signaling current may beusedxtoz' govern different'ca'b signal indications.

Another feature of y invention is rtheprovi sion of transmitting apparatus "for' train} comsition of the? putcircui selectivelyconnected to such-trans- Smitting'fci cuits jby ag manually operable switchingumeans lra ing; different positions so that the cu nl t ci cuitinaywb fi nne e to any *on or-t "all oflthe, transmittingjcircuita y A" codetransmi-tteriisi governed by said one po- 7 first switching means tog-code at times the carrier 1 signaling current. "Such: code transmitter is? provided .with f differe'nt contact members twhichzare operated at"different rates {and e'ach'gsuch code contact member is fincluded in a1p'articula'rv circuit 'p'athzof the output circuit..

A second :manual-l'y' :operablei switching: means having-several difierentpositions is provided and byits :positibni determines" which circuit' path: of

the'outputcircuit is closed and hencedetermines by its positionfwhich one of the: code contact membersis effective to code the "signaling curmunication systems for classification yards wherewith a carrier signaling current iscodedat' difierent codes to provide. different cabfsi'gna'ls ;for the different speeds and movements required for classifying cars, and which codes; of'th'e signaling current are madeto correspond .to .thexdife r ferent indications of a fixed signal. Further more, telephone communication 'is efifcted bea tiongsysten offa switching means i would also preferably fgovern I rent-.j Thi'sfseconda switching means'includes an additional position at which" the output circuit is 'by-pass ed around the contact. members oif'the" icode transmitter for *s fpplyingf at V time's 5 a noncoded 'sighalingk current. I I

" When the 'apparat' s isusedfo'r, communi n classification yard, the; second h or :the railway and when the fixed signal usually provided for displaying a different signal indication for each of the different speeds and movements used to classify cars. Under such circumstances the second switching means by its position provides a specific code for the carrier signaling current for each indication of the fixed signal, and hence there is a code for each of'the different speeds and switching movements to be used in classifying cars.

A second position contact of the first switching means, which position conditions the transmitting apparatus for supplying telephone current, completes a circuit path of the output circuit which by-passes the contact members of a code transmitter and the second switching means and hence for telephone communication the telephone current is delivered directly from the transmitting apparatus to the transmitting circuits according to the position of the previously mentioned other or third switching means.

I shall describe one form of apparatus embodying my invention and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention'when used with a train communication system for a'classification yard. Referring to the drawing, the reference character RY designates the inbound or receiving yard of a classification yard, and which inbound yard is shown as comprising three tracks IT, 2T and 3T. The reference character OY designates theoutbound yard of the classification yard, and this outboundyard is shown as also comprising three tracks 4T, ST and GT. Traiiic normally enters the inbound yard RY from a main track (not shown) to the left as viewed in the drawing. Trafiic leaves the yard RY over a hump track HT andfrom this hump track cars move into the outbound yard OY. In accordance with the usual practice, cars are collected on the several tracks of the inbound yard and are then pushed over the hump by a shifting locomotive. I The movements of the cars from the hump to the several tracks of the outbound yard may be governed by car retarders or car riders as desired, the cars being classified in the several tracks of the yard Y according to the destination of their lading. Shifting locomotives operating in the yard RY or in the yard CY and locomotives pushing cars overthe hump are under the direction of a yard master or operator located at a central ofiice station shown atCF in the drawing.

Although only three tracks are shown for each of the yards RY and OY, it will be understood that each yard may be provided with additional tracks, each of which additional tracks would be connected to the hump track by the customary ladder track. It will also beunderstood that my invention is not limited to a classification yard or'to a classification yard using a hump for the classification of'cars, and this one embodimentof the invention will serve to illustrate the many places where apparatus embodying my invention is useful.

' In'order that the operator located at the central ofiice CF may communicate both by cab signaling and by telephone communication with the crews of the locomotives operating on any track of theyard and thereby direct the movements of such locomotives quicklyand efiiciently, apparatus embodying my invention is provided and which apparatus includes transmitting apparatus located preferably at the central oflice CF and transmitting circuits extending throughout the yard.

The transmitting circuits may take different forms and would preferably be of the type covered by the Letters Patent of the United States No. 2,112,364, granted March 29, 1938, to L. O. Grondahl, for Electric train signaling systems and wherewith the track rails are included in the transmitting circuit. In the specific embodiment of my invention two transmitting circuits are provided, one being associated with the yard RY and the other being associated with the yard OY. The first transmitting circuit includes a line wire LI extending from a, point near the central oflice station to a point A at the extreme left-hand end of the yard RY. At point A, the line wire Ll is connected by a wire 4 to at least i one track rail of each of the tracks of the inbound yard RY. From the point A, the circuit extends through the rails of the several tracks of yard RY in multiple to the hump track HT and thence to a point adjacent the central oflice CF. The track rails may be bonded by the usual rail bonds to improve their electrical conductivity, but such bonds may not be required since the rails are electrically continuous due to the splice bars and bolts of the rail joints.

The second transmitting circuit includes a line wire LO extending from a point adjacent the central oflice CF to a point D at the extreme right-hand end of the outbound yard OY. At point D, line wire L0 is connected by a wire 5 to at least one rail of each of the tracks of the outbound yard OY. From point D, the second circuit extends through the rails of the several tracks of the outbound yard in multiple to the hump track HT and thence back to office station CF.

Each of these transmitting circuits is intended to cooperate with locomotive carried receiving apparatus responsive to communication current of the character here contemplated when such communication current flows in the rails, energy being preferably transferred from the track rails to the locomotive carried apparatus inductively through the medium of an inductor mounted on the locomotive in inductive relation to the track rails. It will be observedthat each transmitting circuit is not shunted by the. wheels and axles of a car or locomotive, and the rails of each track form a branch path in the transmitting circuit so that energy will be transferred to the receiving apparatus irrespective of the track occupied by the locomotive, whether the locomotive is facing in one direction or the other, whether the locomotive is preceded or followed by cars on the same track, and whether the other tracks are occupied by other cars. The structure of such receiving'apparatus may be any one of several forms wellknown to the art and may be of the type disclosed in Letters Patent of the United States No. 2,102,435, granted December 14, 1937, to W. P. Place for Receiving apparatus for communication systems. Such receiving apparatus forms no part of my invention, but it may be helpful in the understanding of apparatus embodying my invention to explain that such receiving apparatus .is normally conditioned for reception and is responsive to a carrier signaling current equivalent to a preselected carrier modulated by a preselected voice frequency for governing a cab indicator and is. automatically conditioned for reception of a carrier telephone current when the signaling current is discontinued, the voice frequencies of such telephone ting circuits electrically,

curr n tems: reprhdueed' at a"loud-'-speaker-'or telephone receiveiz i v I played ir'idi'cates that I the transmitting circu' is energized with signaling current and that the system is in awork'ing condition. The z-zab indithat the Signal' g current is discontinued due either-to -a 'failureof the system or that remoteo'flice station is about to initiate tele"-" cator when extinguished indicates the operator at the phone communication. It is clear that suchcab Y consist ytiieumoauratcn are shifted so that a The 'cab 'indicater when: sis; j

indicator may be controlled through decoding apparatus of the Well-known form and made'to display a 1 distinctive. signal for each of several difi'er'entcodes of the signaling current, andsuch cab signa1 when controlle'd'bycoded signaling current may be used to govern the speed and movement of therloco'motive on which the apparall rfangement' isleflected; v 7 Ihelmicrophone 's'lconne'ctedto the modulav and "to'efiectimodulation terssu ppli'd fro up he oscillator OSI by'the volce irequencic produced bywspeaking into "the microph'one. whenthe modulator-is set for i tsubalnnced condition, thevside bands resulting quel lby are: supplied t BPF wiresl 5t and =16; thet'carrier'bein'g suppressed by the balanced arrangement of the nicdulat'orr 'l'he Cfilter BPF is proportioned and actuated as suppress one side b andand' pass the 'l o furtherassis't inunderstanding the invention, :1 shall "assume that the-lower side band? is suppressed 'an'd: the upper side band is paratus "is mounted. It is to be seen therefore that communication may be effected between v the operator at thecentral. oifice vCF and the crew of 'a locomotivedper'ating on'anyltrack of either yard RY 'or'OYwhen communication current issupplied'to either one or both'of the two transmitting circuits, it being understood, of

- course, that receiving'apparatus. of the form described above is :mountedon' eachsuch locomo tive. w

1 In order to better'sep'arate the two transmitinsulated rail "joints 6 maybe helpful :whenplaced in theihump track in the vicinity of the office station CF, but such insulated rail'joints may not be required.

The transmitting apparatus is shown at the upperportion of the'drawing and this transmita ting apparatus would preferably be located at the central office CF and comprises as essential elements, ancscillator OSI, a microphone M, a'modulator MO, a band pass filter BPF, a power amplifier PA, and a code transmitter CT together with an output circuit and threedifierent Q pper side: band "of; by 'filter BPFto th amplifier upanc l coridenser 1 1 manual operable switching means to be later described. v

The oscillator "0ST," modulator MO, filtenBPli and power amplifier PA are shown conventionally in order specific structure'of each ofthese devicesfforms no part of i I may be any one of several'well-known'types. Furthermore these devices'will beexpl'ained only as required for a full understanding of my -inven-' tion. I E I The oscillator OSI is preferably "of electron tube type and generates a carrier current of a preselected frequency, the frequency of'the carrier current being determined in 'part by a condenser 1.. The arrangement is such that when a relay DR to be referred "to later, is released to close back contact 8 and condenser! is connected to theoscillaton a carrier current of a frequency of say, i v generated, andwhen relay DRI is picked upand condenser l disconnected from the oscillator, the carrier frequency 'is'shifted by an amount equal to a preselected frequency of say 1000 cycles so e that the carrier current then generated is of the frequency of 7000 cycles. The carrier current generated by oscillator OSI is delivered to the modulator MO over wires 9 and It]. The modulator MO 7 is preferably of the balanced electron tube type, the connections of which are governed by relay DBL When relay DRl is released, 0105- ing its back contact 'I I ,a connection is completed by which a balanced push-pull arrangementis ef-,

, fected for the modulator and when relay DH! is picked up to close fronthontact M, the connecto simplify the drawing since the for examp1e',-6000-c ycles per second is my present invention andsuch devices ",The' output side of filter BPF is I con- Ver wires l'l and I8 to theinpu't' ter passed; necte min 15 f'ithe power amp'liiier PA. "When the can-i urrent' of- 600 0' cyc1esper second is used a assumedyher einbefor'e, and a voice frequency e 01 Oli t0-2500 cycles is considered, the the' telphone current passed en Trelay so that the; carrier "current 'is of v .7000 rid the modulator lvlb is 'shiftedzto a parallel} rrangement then this, carrier current 'rier 5c renames-med bylthe voice frequency or ioooycynesp- 'This carrier current ofnflOOO u sts use'c l as a 'signaling currcnt. a

Thelam'plifier PA'fsmreferably ofthe electron tubet e andwheneither theftelephone current ofthe r ang-e of 6500 8500 cycles or the signalcmrenitj cf UQO cycles is applied-to its input terminals such "current is amplified to a *rela tively hig energy leveland'supphed to an output r t Theoutput circuit includes -a secondary f an outpu't transformer 20 whose Relay om controlled cui biased ":typeipush button PBand'the relay DR? trp'getl'ierv withffiu'sh buttonfPB f orm' a first 'manu allly operable switching 'meansfor conditioning the itrains'r r-i ittir-ig apparatus to supply either the carrier sigmimgmmm or' the carrier telephone current. It followsthat the normal 'or' first positio'n o-f' thfe first "switohing'ineans conditions'the transmittingapparlatus Itd'fsuppl'y the carrier signaling current to thefsecondary'wi'nding 1 Sci the outp fticircuitand the reverse or "second position I of thisfirst switching 'm'eans conditions "the airparatus'? to supply'the carrier telephone current tothe seconiiarywinding H! of the output circuit.

Additional for this first switching meansiwill appear he'reinafter.v

I l-1e output circuit" connected to secondary o, windingl o'f transformer is provided'with several fdifie'rent circuit paths five of which paths are governed by a second' "manually operable switching ineains', here shown as consisting or four: separate "circuit I controllers P1, P2; P3 and P4. Each suit contr oller" of the second" switch i-r ig means mar in A 4 v Seated in the" drawing by solid l v second orreverse position illustrated lei "dotted lines in the drawing."

Q i A code transmitter orcoder CT'is provided is "of'ith'eran e of i pass'edz bs 'th'e filter BPF 'since- "the carrie'r current of 1000 cycles is the equivahe upper side band' 'of the 6000:0ycle dar o fliiirigirzzrii's connectedit t output I w h over an obvious cir-" t-includi'ng (a normally'closed contact 22 of 'a operable to' ei tlier a norand as here shOWn it is of the relay type having three contact members I80, I20 and I which are operated as long as an operating winding 23 of the coder is supplied'with energizing current. Winding 23 is provided with a circuit which can be traced from terminal B of a convenient source of current, such as a battery, not shown, front contact 24 of relay DRI, winding 23, a normal closed contact 25 of circuit controller P4 and to terminal C of the same source of current. Hence when the first switching means is set at its first position with relay DRI picked up and controller P4 of the second switching means is set at its normal position, coder CT is active to operate its contact members, the arrangement being such that contact member I80 is operated to engage a contact 26 at the code rate of 180 times per minute, contact I 20 is operated to engage a contact 21 at the code rate of 120 times per minute and contact member I5 is operated to engage a contact 28 at the code rate of 75 times per minute. Each of the contact members I80, I20 and I5 is interposed in one of three paths of the output circuit and. which three paths are also controlled by controllers PI, P2 and P3 of the second switching means.

The circuit controllers of the second switching means are also used to govern a fixed signal HS located along the hump track HT for indicating to a locomotive pushing cars over the hump the speed and movement desired. This signal HS may be of any standard type of fixed signal and as here shown is a color light signal capable of displaying any one of four different indications; namely, a green light to indicate proceed at normal hump speed, a yellow light to indicate proceed at slow hump speed, a steady red light to indicate stop and a flashing red light to indicate back up, The control efi'ected by the second switching means over the three circuit paths of the output circuit which includes contact members of code transmitter CT and over the indication of the fixed signal HS is such that a distinctive code for the carrier signaling current is effected for each signal indication with the result that a cab indicator of receiving apparatus mounted on the locomotive would be made to provide a distinctive cab signal for each indication of the fixed wayside signal, and as here contemplated the 180 code for the carrier signaling current controls a cab signal which corresponds to the green light of the fixed signal to indicate proceed at normal hump speed, the 120 code for the carrier signaling current controls a cab signal which corresponds to the yellow light of the fixed signal to indicate proceed at slow hump speed, the '75 code controls a cab signal which corresponds to the flashing red light of the fixed signal to indicate back up and non-coded signaling current controls a cab signal which corresponds to the steady red light of the fixed signal to indicate stop.

The output circuit is provided with additional circuit paths which by-pass the output circuit around the code transmitter and. the second switching means and each of these additional circuit paths includes a second position contact of the first switching means, so that when the transmitting apparatus is conditioned for supplying telephone current the output circuit is completed for by-passing the telephone current around the code transmitter and the second switching means. Such additional circuit paths will be described when the operation of the apparatus is described.

, The connections of the output circuit to the transmitting circuits are further governed by a third manually operable switching means comprising two circuit controllers CI and C2.

It is believed that the manner whereby the three different switching means govern the transmitting apparatus and the connections of the output circuit to the transmitting circuits can best be understood by a description of the apparatus. In describing the operation of the apparatus, I shall first assume that a locomotive provided with proper receiving apparatus is pushing cars over the hump and hence occupies the hump track HT to the left of the central oifice station CF. Since the push button PB is biased to its released position, the first switching means occupies its normal position so that relay DRI is picked up to condition the transmitting apparatus to deliver carrier signaling current. The circuit controller P4 of the second switching means is placed by the operator at its normal position and the coder CT is active. In the event the operator desires the locomotive to proceed at normal hump speed, circuit controllers P2 and P3 of the second switching means are set at their normal positions and circuit controller PI is set at its reverse position. The operator would also set each circuit controller CI and C2 of the third switching means at its right-hand position as illustrated by the solid lines in the drawing.

With circuit controller PI reversed, a simple circuit easily traced is completed for a lamp 29 of signal HS and that lamp is illuminated to display a green light. A first circuit path of the output circuit is also completed at the reverse position of contact 32 of circuit controller PI so that carrier signaling current coded at the 180 code rate flows from the top terminal of secondary winding I9 over front contact 3I of relay DRI, contact I26 of coder CT, reverse position of contact 32 of controller PI, wire 33, contact 34 of controller CI, wire 35, line wire LI of the first transmitting circuit to point A, back the track rails of the tracks of the inbound yard and the track rails of the hump track HT, wire 36, contact 31, of controller CI and wire 38 to the lower terminal of secondary winding I9. Since this signaling current is coded at the code rate, the cab indicator of the locomotive occupying the hump track HT or any of the yard tracks leading to the hump track will be conditioned to display a corresponding indication which indication conveys the information to the locomotive crew to proceed at normal hump speed. This cab signal indication is continuously displayed and would also serve to indicate to the locomotive crew an operative condition of the communication system.

In the event the operator at the central oflice desires the locomotive to proceed at slow hump speed, the first and third switching means are left as above described but controllers PI, P3 and P4 of the second switching means are set at their respective normal positions and controller P2 is reversed. A yellow lamp 39 of fixed signal HS is now provided with a circuit including the normal position of contact 30 of controller PI and reverse position of contact 40 of controller P2, and lamp 39'is illuminated to cause the signal HS to display a yellow light. With the controller P2 reversed a second circuit path of the output circuit, and which circuit path includes contact member I20 of the coder, is closed and made effective so that carrier signaling current flows from the top terminal of secondary winding I9,

It is to be seen, therefore, that I have provided simple and inexpensive transmitting apparatus for train communication systems incorporating novel means for supplying carrier signaling current coded at diiferent code rates or noncoded and for supplying carrier telephone current and which currents can be supplied to one or all of a plurality of different transmitting circuits associated with different stretches of railway track.

Although I have herein shown and described only one form of transmitting apparatus for train communication systems embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In apparatus for a train communication system, the combination comprising, transmitting apparatus capable of producing a carrier telephone current or a signaling current equivalent to said carrier modulated by a given voice frequency, a first manually operable switching means having a first position to condition the transmitting apparatus to produce said carrier signaling current and a second position to condition the transmitting apparatus to produce said telephone current, an output circuit coupled to the transmitting apparatus to receive such currents and provided with three different circuit paths, a code transmitter having a contact member included in a first one of said circuit paths, a second manually operable switching means having a first position for closing said first one of said circuit paths and a second position for closing a second one of said circuit paths, a second position contact of said first switching means for closing the third one of said circuit paths, and a transmitting circuit extending along a stretch of track and connected to said output circuit.

2. In combination with transmitting apparatus capable of supplying a carrier telephone current or a signaling current equivalent to said carrier modulated by a preselected voice frequency, an output circuit to receive such currents from the transmitting apparatus and provided with a plurality of different circuit paths, a code transmitter having a contact member operated at a predetermined code rate and interposed in a selected first one of said circuit paths, a first manually operable switching means having a first position to condition the transmittin apparatus to supply said signaling current and a second position to condition the transmitting apparatus to supply said telephone current and to close a second selected one of said circuit paths, a second manually operable switching means having a first position to close said first one of the circuit paths and a second position to close a selected third one of the circuit paths, two transmitting circuits one extending alon a first stretch of track and the other extending along a second stretch of track, and a third manuall operable switching means having different positions for connecting said output circuit to either one or both of the transmitting circuits.

3. In apparatus for a train communication system, the combination comprising, transmitting apparatus capable of producin a carrier telephone current or a signaling current equivalent to said carrier modulated by a given voice fre- 'quency, a first manually operable switching means having a first position to condition the transmitting apparatus to produce said carrier signaling current anda second position to condition the transmitting apparatus to produce said telephone current, an output circuit coupled to the transmitting apparatus to receive such currents and provided with three different "circuit paths, a code transmitter effective when energized to operate a contact member at a preselected code rate and which contact member is included in a first one of the circuit paths of the output circuit, a second manually operable switching means having a first and a second 'position for closing said first path and a second path of the output circuit respectively, a second position contact of said first switching means for closing the third path of the output circuit, means including a first position contact of the first switching means and a contact of the second switching means to energize said code transmitter, a transmitting circuit extending along a stretch of track, and other switching means to connect at times the output circuit to said transmitting circuit.

4. In apparatus for a train communication system the combination comprising, transmitting apparatus capable of producing a carrier telephone current or a signaling current equivalent to said carrier modulated by a given voice fre- -quency, a first manually operable switching means having a first position to condition the transmitting apparatus to produce said carrier signaling current and a second position to condition the transmitting apparatus to produce said telephone current, an output circuit coupled to the transmitting apparatus to receive such currents, a code transmitter having a first and a second contact member and which members are operated at difierent code rates; a second manually operable switching means having a first position to close said output circuit through said first contact member, a second position to close the output circuit through said second contact member and a third position to by-pass the output circuit around said contact members; means including a second position contact of said first switching means to by-pass the output circuit around said second switching means, and a transmitting circuit effective to transmit such currents and extending along a stretch of track and connected to said output circuit.

5. In apparatus for a train communication system, the combination comprising, transmitting apparatus capable of producing a carrier telephone current or a signaling current equivalent to said carrier modulated by a given voice frequency, a first manually operable switching means having a first position to condition the transmitting apparatus to produce said carrier signaling current and a second position to condition the transmitting apparatus to produce said telephone current, a code transmitter having three difierent contact members which are operated at different code rates, a transmitting circuit effective to transmit such currents and extending along a stretch of track, an output circuit to connect said transmittin apparatus to said transmitting circuit, a fixed signal to govern traffic moving over said stretch of track and capable of displaying four different indications; a second manually operable switching means having four different positions and provided with contacts closed at a first position to. interpose a first one of said code contact members. in the output circuit and to close a first position circuit of said fixed signal, other contacts closed at a around the said second switching means, and still another switching means-having different posisecond position to interpose a second one of said members in the output circuit and to close a third position circuit of the fixed signal, and

other contacts closed at a fourth position to bypass the output circuit around said code contact members and'to close a fourth position circuit of the fixed signal; and means includin a second position contact of said first switching means to by-pass the output circuit around said second switching means.

6. In apparatus for a train communication system, the combination comprising, transmitting apparatus capable of producing a carrier telephone current or a signaling current equivalent to'said carrier modulated by a givenvoice frequency, a first manually operable switching means having a first position to condition the transmitting apparatus to produce said carrier signaling current and a second position to condition the transmitting apparatus to produce saidv telephone current, a code transmitter having at least two different contact members each of which is operated at a code rate distinctive for that contact member, a transmitting circuit effective to transmit said telephone and signaling current and extending along astretch of track, a fixed signal to govern traffic along said stretch of track and capable of displaying at least two different indications, an output circuit to connect said transmitting apparatus to said transmitting circuit and provided with at least three different paths a first and a second ofv which paths each includes a distinctive one of said contact members; a second switching means operable to three 1 different positions and provided'with contacts closed at a first position to close the first path of tions for selectively controlling the connections of the output circuit to said transmitting circuits.

8. In apparatus for a train communication system for a classification yard the combination comprising, transmittingapparatus located at a central ofiice and capable of producing a carrier telephone current or a carrier signaling cur-' rent, a first switching .meansat said central office and having a first position to condition the transmitting apparatus to produce said signaling current and a second position to produce said telephone current, an output circuit coupled to the transmitting apparatus to receive such currents, a code transmitter having a plurality of different contact members operated at different code rates,

a fixed signal located along a track of the yard to govern the classification of cars andcapable of displaying a plurlity ofdistinctive signal indictions, a plurality of operating circuits for said signal to effect said signal indications, a second switching means located at said ofiice and having a plurality of different positions each of which positions is effective to interpose a selected one of said contact members in said output circuit and toclose a selectedone of said operating circuits for said fixed signal, means including a secondposition contact of said first switching means to by-pass the outputcircuit around said second switching means, a transmitting circuit effective to transmit said signaling and telephone ourrents'and extendng at least along the track associated with said fixed signal, and another switching means at said office and effective at times to connect said output circuit to said transmitting the output circuit and to close a first operating circuit for said fixed signal, other contacts closed at a second position to close the second path of the output circuit and a second operating circuit for said fixed signal and other contacts closed at a third position to closethe third path of said output circuit; and means including a second position contact of the first switching means to bypass the output circuit around said second switching means.

'7. In apparatus for a railway train communication system the combination comprising, transmitting apparatus capable of producing a carrier telephone current or a carrier signaling current, a first switching means having a first position to condition the transmitting apparatus to produce said signaling current and a second position to condition the transmitting apparatus to produce said telephone current, a first and a second transmitting circuit extending along two circuit.

v 9. In apparatus'for a train communication system for a classification yard the combination comprising, transmitting apparatus located at a central ofiice and capable of producing a carrier telephone current or a carrier signaling current, a first switching means at said central office and having a first position tolcondition the transl mitting apparatus to produce said signaling current and a second position to produce said telephone current, an output circuit coupled to the transmitting apparatus to receive such currents, a code'transmitter having a pluralityof different contact members operated at different code rates, a fixed signal located along a track of the. yard to governthe classification of cars and capable of displaying a plurality of distinctive signal indications, a plurality of operating circuits for said signal to effect said signal indications, a second a switching means located at said office and having different stretches of track and each effective to transmit said signaling and telephone currents, a code transmitter having a contact member operated at a preselected code rate, an output circuit for connecting the transmitting apparatus to said transmitting circuits, a second switching means having different positions effective at one position to interpose said contact member in the output circuit and at another position to by-pass said output circuit around said contact member, means effective at said first'position of said first switching means to by-pass the output circuit a plurality of different positions-each of which positions is effective to interpose a selectedone of said contact members in said output circuit and to close a selected one of said operating circuits .for said fixed signal, means including a second position contact of said first switching means to by-pass the output circuit around said second switching means, a'first transmitting circuit extending along the track associated with said fixed signal and a first selected portion of said yard, a second transmitting circuit extending along a second selected portion of said yard, each of said transmitting circuits effective to transmit, said signaling and'telephone currents, and a third switching means at said office and having different positions to connect said output circuit to either one or both of said transmitting circuits. I PHILIP P. ASH.