US2168880A

US2168880A - Telephone system

Info

Publication number: US2168880A
Application number: US179124A
Authority: US
Inventors: Edward S Peterson
Original assignee: Associated Electric Laboratories Inc
Current assignee: Associated Electric Laboratories Inc
Priority date: 1937-12-10
Filing date: 1937-12-10
Publication date: 1939-08-08
Anticipated expiration: 1956-08-08
Also published as: FR847279A

Description

Aug. 8, 1939. E. s. PETERSON I TELEPHONE SYSTEM Filed Dec. lO, 1957 3 Sheets-Sheet 1 EDWARD S. PETERSQN ATTORNEYS.

Aug. 8, 1939. E'. s. PETERSON 2,168,880

TELEPHONE SYSTEM Filed Dec. lO, 1957 3 Sheets-Sheet 2 EDWARD S. PETERSDN BYww' M,

ATTORNEYS.

Aug. 8, 1939.

lO, 1957 3 Sheets-Sheet 3 Filed Deo.

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vmm 0mm Oom mmm mm M .mu-n- HVVQVDR. EDWARD 5. PETERSDN BY M, afmy M ATTORNEYS Patented Aug. 8, 1939 UNITED 'STAT-ES r' PATENT O FF I CE TELEPHONE SYSTEM Edward S; Peterson,

Elmwood Park, Ill.,y assignor Application-December 10, 1937, Serial No. 179,124

23 Claims.

The present invention relates generally to-signalling systems and has for one of its objects the provision of an improved telephone system adapt- Ved for use on a train vcomprising a plurality of cars or vehicles.

The utility of providing telephone facilities on av railway train for communicationV between the various cars has been recognized for some time and, as a result, telephone apparatus has been provided as standard equipment in the constructionof the railway cars of recent design. One of the chief points of utility infproviding a system of this character is that of kenabling the engineer in the locomotive cab to be'advised by members Vof the train crew as to the condition ofthe train from telephone stations located at strategic points incertain of the'cars of the train. VSpecically, the greatest use islfound in switching operations wherein a trainattendant may relay information over the telephone system to the locomotive engineer from a telephone station located at the rear Aof the rear car, thereby to control movement of the train in a rearward direction. As is wellknown, it is frequently necessary to provide two locomotives on trains which are heavily 'loaded and which are required to travel over routes having highly gradedv roadbeds. Inthis type'of train, it isihighly desirable that telephone equipment be provided such that communication may be had between the two locomotive cabs and between each of the cabs and other telephone stations located in the other cars of the train. Trains are usually made upby the train crew prior to each run and no set rule is followed as regards the particular cars which will make up the train in any given case or the manner in which these cars will be arranged. This is particularly true with reference to the manner in which the two locomotives of a double-header train are connected for use. By Virtueof this indiscriminate mode of assembling the 'cars making up a train, the problem is raised of'providing a telephone system wherein the telephone stations may be connected in a variety of ways to form a uniied system and wherein the mode of operation of the system is the same irrespective of the arrangement of the component stations.

It is a further object of the present invention! therefore, to provide an improved and exceeding- .ly simple arrangement whereby communication facilities are provided between the cab of either of two locomotives ofadouble-headertrain and other ltelephones located in the other cars of the train, andv also directly between the Vtwo cabs,Y and wherein theapparatus in each cab is so arranged that the locomotives may be'disposedin any-de sired order without disturbingthe communication facilities.

f More specifically, it is an object of theinvention to provide telephone equipment of improved and economical arrangement for use on avehicle, such, for example, as a locomotive cab, which may be connected ina telephone system in'anyone'of a number of ways to providecommunication facilities for the vehicle rand wherein the mode of` operating the equipment is the same'irrespective ofthe manner in'which the equipment-is connected in the system.

In the speciicembodiment of theinvention de- 'scribed hereinafter, lthere are provided a plu- `15 rality of telephone stations respectivelyv located onr certain `of the several vehicles makingup a railroad train, which stations are interconnected by a lline circuit comprising av plurality of conductors. Two telephone stations are located Vin each of the `two locomotive cabs embodied inthe train Yand one station is provided-in eachv of cer- -tainofthe other cars equipped for telephone service. The equipment at each station comprises a telephone transmitter and receiver normally'disconnected from the line circuit and a' manually operable switch operative to connect the associated transmitter and receiver tothe circuit. Since the primary purpose of the system is to provide facilities for transmitting information to the'engineer, a signal device is only provided at one of the stations located in each of the locomotive cabs. The arrangement is such that the signal devicev provided at'the one station in each 'cabmay directly be energized through the operation of a manually operable switch provided at the other station located in the same cab over a circuit independent of the line circuit, or itmay be energized in response to the operation of a manuallyoperable switch provided at one of the 40 stations located in the other locomotive cab. As regards the energization of -thesignal devices on calls initiated at stations other than the locomotive Vcab stations, means are- -provided responsive to the actuation of a manually operable switch at one of these other stations for causing the simultaneous energization of all of the signal devices. When such a call isanswered at one of the stations in one of the cabs, control apparatus is caused to operate to cause the deenergization of all of the signal devices. By this arrangement the method of signalling is rendered selective as regards calls between the cab stations, but is nonselective on calls originating at a station other than a cab station.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the specication taken in connection with the accompanying drawings, in which one embodiment is illustrated. In the drawings, Figure 1 illustrates the apparatus provided at the two telephone stations located in the cab of the rst locomotive of a double-header train, Fig. 2 illustrates the similar apparatus provided at the two stations of a second locomotive, and Fig. 3 illustrates the apparatus provided, respectively, at two telephone stations located in two different cars of the train following the two locomotive cabs.

Referring now more particularly to the drawings, there is illustrated an improved telephone system which is particularly well suited for the application mentioned above, namely, on a train comprising a plurality of Vehicles, at least certain of which, such, for example, as the locomotives, are interchangeable. In brief, the system comprises a plurality of telephone stations |00, |50, 200, 250, 300 and 350 interconnected by a line circuit divided into sections |04, 204, 304 and 301. As indicated in the drawings, the two stations |00 and |50 are located in the cab of the first locomotive of the train, the two

stations

200 and 250 are located in the cab of the following or second locomotive of the train, the station 300 is located in the baggage car, and the station 350 is located at the rear of the rear car, which latter car may be the observation car of a passenger train` or the caboose of a freight train. The enumerated sections of the line circuit extend between the several cars and terminate in voice frequency current repeaters. Thus, the line circuit section |04 comprises a pair of conductors |05 and |06, respectively connected to the terminals of one winding |9l, |92 o1" a repeating coil located in the first locomotive cab at the station |00. The conductors of this pair are also connected to the respective terminals of one winding 293, 294 of a repeating coil 290 located at the station 200 in the cab of the second locomotive. The other winding |93, |94 of the repeating coil |90 has its terminals connected, respectively, to the conductors |02 and |03 of the line circuit section |0I, this section being opencircuited, as shown, with the locomotives arranged in tandem in the order indicated but being provided for use in the event the order of the locomotives is reversed, The repeating coil 290 includes a winding 29|, 292 having its opposite terminals connected, respectively, to the

conductors

205 and 206 of the line circuit section 204. These last-mentioned conductors also terminate at the respective terminals of one winding 343, 344 of the repeating coil 340 located at the station 300. The other winding 34|, 342 of the coil 340` is arranged to be connected by the pair of

conductors

305 and 306 to the winding 313, 314 of the repeating coil 310 located at the station 350. Finally, the other winding 31|, 312 of the repeater 310 is connected by way of the pair of

conductors

308 and 309 making up the line circuit section 301 to the opposite terminals of the telephone hand set located at the station 350.

Eachof the telephone stations 00, |50, 200, 250, 300 and 350 comprises a transmitter and a receiver normally disconnected from the line circuit and preferably in the form of a hand set, and a manually operable switch which is operative to cause the associated transmitter and receiver to be connected to the associated section of the line circuit. More specifically, there is provided at the rear car station 350 a hand set 360 comprising a receiver 36| and a transmitter 362. This hand set also has embodied therein a manually operable switch comprising the springs 364 and an actuating member in the form of a push button 363. Similarly, the apparatus at the station 300 comprises a hand set 330 having embodied therein a receiver 33| and a transmitter 332, together with a manually operable switch including the springs 334 which normally occupy the open-circuited position illustrated in the drawings but may be moved into engagement through the actuation of an associated push button 333. The last-mentioned station also includes a lockout relay 3 0 which forms means responsive to the operation of the switch in the hand set 360 for preventing the transmitter 33| and the receiver 332 from being connected tothe terminals of the repeater winding 34|, 342 when the line circuit is busy in connection with a call from the station 350 to one of the locomotive cab stations. It will be noted that the circuit arrangement of the apparatus located at the station 300 is slightly different from that of the apparatus provided at the station 350 in that the manually operable switch comprising the springs 334 is not effective directly to connect the associated transmitter and receiver to the conductors of the line circuit section 304, but rather is effective to complete the operating circuit for a second relay R320, which relay, in turn, performs the line switching functions. The relay R320 is also operative to prevent a call from being initiated at the station 350 when the line circuit is busy in connection with a call originated at the station 300.

The apparatus provided in each of the locomotive cabs is identical and, hence, it is believed that a brief description of the apparatus located in cab No. l, as illustrated in Fig. l, will suffice for the present, especially in View of the fact that the corresponding elements in cab No. 2, as illustrated in Fig. 2, are identified by the same reference numerals prefixed with the two hundreds digit rather than the one hundreds digit. As illustrated in Fig. 1, the apparatus in the iirst locomotive cab at the station |00 comprises a hand set |40 having embodied therein a receiver |4| and aV transmitter |42 together with a manually operableswtch comprising the springs |44 and the push button |43. Similarly, the apparatus at the station |50 comprises a hand set |10 including a receiver |1| and a transmitter |12 and having embodied therein a manually operable switch comprising the springs |14 which are under the control of a push button |13. This station also includes a device in the form of a relay RI 60 which operates in response to the actuation of the push button switch to connect the transmitter |12 and the receiver |1| across the conductors |05 and |06 of the line circuit section |04. Also included at the station |00 is a signal device in the form of a bell ringer |81 which comprises an operating magnet |89 and Contact springs |88 under the control of the bell striker. This signal device includes an operating circuit which is independent of the line circuit and is arranged to be completed in response to the actuation of a push button switch |15 provided at the station |50. By this arrangement, a person calling the station |00 from the station |50 may signal the first-named station directly and withoutY affecting the'signal device provided at the station 200. The signal device noted also includes van alternative operating circuit, traced hereinafter, which is under the control of each of two relays R||0 and R|20. As will be pointed out in detailA hereinafter, the relay R! |0, and also the corresponding relay R2 l0 provided at the station 200, comprise means responsiveto the operation of either ofthe two push button switches embodied in the apparatus at the station 300 and the station 353, respectively, for'completing the alternative operating circuits for the signal ydevices |81 and-281 locatedprespectively, at the stations |00 and-200. The signal devices noted are deenergized, following rtheir energization, through the provision of a' relay R|30 at the sta- Vtion |00 and a corresponding relay R230 at the station 200, which relays are respectively arranged to respond to the actuation of the manually operable push'button switch provided at the respective two stations or to thel operation of the corresponding relay at the other station.

rI-he alternative operating circuit for the signal device |81'may alsobe completed through the operation of the relay Rl20but, with the cabs arranged inthe order described above, this relay is not susceptible of being energized. At the station 263, however, the'corresponding relay R220, which is arranged to complete the alternative operating circuit for the signal device 281, operates in response to the actuation of a second manually operable switch |80 provided at the station 00. The relay R|30 provided at the station |00 not only functions to cause the signal device |31 to be deenergized under certain conditions, but is also' operative to connect the transmitter M2 and the receiver |ll| across the line conductors |65 and |03 of the line circuit section |04. Similar" functions are performed` by the corresponding relay R230 provided at the' station 200.

Current for energizing the various relays indicated in'the drawings and thetwo signal devices is obtained from a common source which, preferably, comprises the storage battery conventionally 'Y embodied as standard equipment in each of the locomotives. In order to facilitate a description of the circuits involved, this source'has not been illustrated inthe drawings, but it is explained that the positive terminal of the source is connected to all circuit conductors indicated as terminating at ground whereas the negative terminal of the source is connected to the various negative terminals illustratedy in the drawings. Sinceeach of the'transmitter and receiver cells embodied in the various hand sets may be of any standard' commercial construction, these elements have been only schematically illustrated in the drawings. It is pointed out,.however, that reach of the transmitters |02, |12, 242,212, 332

and 332 is preferablyv of the self-powered type which obviates the necessity-of `using an auxiliary current source for voice frequency current transmission. Several Vwell-known transmitters of this type are commercially available. In brief, this type of transmitter usually comprises a diaphragm f which is connected by means of a sturdy but very light connecting rod tovantV armature balanced betweenV the poles of yan extremely powerful permanentr magnet. In its operation, and when sound waves impinge upon thel diaphragm, the diaphragm vibrates in accordance with these waves to transmit the-vibrations'to the armature. The armature, in turn, vibrates and sets up a induced voltage thus generated varies in ampli- 5 tude and frequency in accordance with the amplitude andintensityof the input sound waves.

As indicated above, with the arrangement described, it is only possible for the locomotive cab stations to be called. Referring now to the 0p-- 10 eration of the apparatus to complete a connectionbetween the station 350 and oneof the two stations |00 and 200, it is pointed out that the call is initiated in response to the actuation of the button 333 embodied in the hand set 360. 15

This results in the completion of a simplex circuit for energizing the lockout relay R3|0 provided at the station 360, one branch of this circuit extending from ground on the conductor 365 by way of the closed switch springs 364i, the=20 conductor 366, the winding 313, the conductor 305, RAS i3, RC3 I4, RA323 and through the winding of R3|0 to battery, and the other branch extending from the conducto-r 366 by way of the Winding 311|, the line conductor 306, RA3|6525 RAMI', and RA324 and through the winding oi R3|0 to battery. The relay R3|0, upon operating, opens, at RA3I2, a point in the operating circuit for R320, thereby to prevent the transmitter 332 and the receiver 33| at the station-130 V366 from being connected to the conductors of the line vcircuit in response to the operation of the push button 333. At its armatures RA3|2 and RA3|5 and their respective associated armatures RA3|3 and RA3|3, the relay R3|0 connects' -35 the

line conductors

305 and 306 to the opposite terminals of the repeater coil winding 32E, 322. At RA3|3 and RCSM, the relay R3|6 opens a point in its original operating circuit, but only after an alternative branch circuit has been4 com-i140 pleted, by way of RA3l3, RA3|2 and the Winding 34|, for maintaining itself energized.

At RA3| the relay R3|0 completes a simplex `circuitfor energizing R2|6 located at the station 200,'one branch of this circuit extending-1215 from ground at theV armature noted by way of the conductor 3|8, the Winding 323, the line conductor 205, the winding 23|, the switch springs 285 and 286, RA233, the winding of R2!!! and the conductor 2|5 to battery. The other branchiio of the simplex circuit extends from ground at RA3|| by Way of the conductor 396, the winding 334, the line conductor 206, the winding 292, the switch springs 285 and 286, RA233, the winding of R2|0 and the conductor 2|5 to battery. Thefiffi relay R2|0 now operates to complete, at RA2| i, the above-noted alternative circuit for energizing the signal device 281, which circuit extends from ground as applied to the conductor 2|6 by Way of RAZII, the winding of the magnet 289 andf` the springs 238 to battery. Through the circuitinterrupting action of the springs 230, the signal device 281 is caused to operate to give an audible indication that the station 200 is being called.

`The` relay REW: upon Opelng, also functionsli' to complete a simplex circuit for energizing Ri i0 embodied in vthe apparatus provided at the station |00. One branch of this circuit extends from ground on the conductor 2|1 by Way of the upper winding of R230, the conductor 2|6,-'70

RC2M, RAZIE, the conductor 2|9, the switch springs 283 and 282, the winding 233, the line conductor |05, the winding |9|, the switch springs |35 and |86, RAl33, the winding of Ri i0 `and the-conductor ||5 -tobattery. The otheri'Y-l branch of this circuit is quite similar to that just described but extends by way of the winding 294, the line conductor |06 and the winding |92 rather than by way of the winding 233, the conductor |05 and the winding I9I. Due to the relatively high resistance of the winding of RIIO, the relay R230 does not operate when its upper winding is energized over the above-traced circuit. The relay RI I0, however, operates to complete, at RAIII, the above noted alternative circuit for energizing the signal device |81, this circuit extending from ground on the conductor I I6 by way of RAI I I, the winding of the magnet and the contact springs |88 to battery. Due to the circuit interrupting action of the contact springs |88, the signal device |81 operates to give an audible indication that the station |00 is being called.

Obviously, the above-described operations occur each time the push button 393 embodied in the hand set 360 is depressed. If desired, this push button may be actuated in accordance with a coded signal selectively to indicate which of the two stations |00 and 200 is being called. It may happen that the trainman who initiates the call desires to converse with the engineers in both locomotive cabs, in which case a coded signal indicating the non-selective call may be transmitted through proper manipulation of the push button 363. Following operation of the push button 363 to signal the desired station, this button is held depressed to maintain R3|0 operated. With this relay operated the

conductors

305 and 306 of the line circuit section are maintained connected to the opposite terminals of the repeating coil winding 34|, 342 andthe operating circuit for R320 is held open.

Assuming, for the moment, that the call is intended for the station 200, the desired connection is established when the call is answered at this station by actuation of the button 243 ernbodied in the hand set 240 to move the contacts carried by the springs 244 into engagement. In response to this operation, acircuit is completed for energizing R230, this circuit extending from ground on the conductor 2I1 by way of the upper winding of R230, the conductor 223, the switch springs 244, the resistor 222 and the conductor 2|5 to battery. The resistor 222 is a current determining resistor and the value thereof is selected so that the full rated current for the upper winding of R230 is passed through this winding when the springs 244 are closed. Hence, R230 is caused to operate when energized over the abovetraced circuit and, upon operating, opens, at RA233, a point in the above-traced operating circuit for R2I0. The relay R2|0 now restores to open, at RAZI I, the alternative operating cir- .cuit for the signal device 281. At RA2|2 and RC2|4, the relay R2I opens a point in the simplex circuit, traced above, for energizing RI|0, causing the last-mentioned relay to restore to open, at RAI I I, the alternative operating circuit for the signal device |81. Thus, it will be seen that, when the push button switch incorporated in the Hand set 240 is operated, the two signal devices |81 and 281 are deenergized. At RA232, the relay R230 completes a simplex holding circuit for itself, one branch of this circuit extending from ground, at the operated armature RASI I, by way of the conductor 3I8, the winding 343, the line conductor 205, the winding 29|, the switch springs 285 and 286, RA232, the lower winding of R230 and the conductor 2|5 to battery. The second branch of this circuit is substantially similar to that just traced but extends by way of the winding 344, the line conductor 206 and the winding 292 rather than by way of the winding 343, the conductor 205 and the winding 29| as included in the rst branch of the circuit, traced above. Thus, the relay R230 is held operated independently of the push button 243 so long as the push button 363 is held dev pressed.

When the relay R230 operates, it also functions to complete, at RA23I, a path for connecting the transmitter 242 and receiver 24| across the

line conductors

205 and 206 of the line circuit section 204, this path being more or less obvious and including the

conductors

246 and 241. As thus connected, a talking circuit, comprising the

line circuit sections

204, 304 and 301 and the repeating coils 340 and 310 is completed between the station 200 and the station 350.

Before describing the release of the connection and in order to give a full description of the operation of the apparatus, it will now be assumed that the call is answered at the station |00 rather than at the station 200. In this case, the push button |43 is depressed by the answering party to complete a circuit for fully energizing the upper winding of R|30, this circuit extending from ground as applied to the conductor |I1 by way of the upper winding of R|30, the conductor |23, the switch springs |44, the resistor |22 and the conductor |I5 to battery. Upon being energized over the above-traced circuit, RI30 operates to open, at RA|33, a point in the above-traced circuit for energizing RIID, causing this last-mentioned relay to restore to interrupt, at RAI I I, a point in the alternative operating circuit for the signal device |81. At RAI3 I, the relay RI30 completes a path comprising the conductors |46 and |41 for connecting the transmitter |42 and the receiver I4| across the line conductors |05 and |06 of the line circuit section |04, thereby to complete a talking circuit including the section |04, the repeater 290, the section 204, the repeater 340, the section 304,

the repeater 310 and the section 301, which extends between the stations |00 and 350. At RA|32, the relay RI30 completes a simplex circuit for energizing its lower winding in series with the upper winding of R230, one branch of this circuit extending from ground on the conductor 2|1 by way of the upper winding of R230, the conductor 2|8, RC2I4, RA2I2, the conductor 2 I9, the switch springs 283 and 282, the winding 293, the line conductor |05, the winding |9I, the switch springs |85 and |86, RAI32, the lower winding of RI30 and the conductor ||5 to battery. The other branch of the circuit is similar to that just described, but includes the winding 294, the line conductor |06 and the winding |92 rather than the winding 293, the line conductor |04 and the winding ISI. The relay R230 operates when its upper winding is energized over the above-traced circuit to interrupt, at RA233, a point in the above-traced operating circuit for R2|0, causing the last-mentioned relay to restore to open a point in the alternative operating circuit for the signal device 281. At RA232, the relay R230 completes the above-traced holding circuit for itself. Thus, R230 remains operated for the duration of the conversation and, in its operated position, holds the receiver 24| and the transmitter 242 connected across the

conductors

205 and 206 of the line circuit section 204. Also, with this relay operated, R2I0 circuit.' Hence, if the push button 243` is released Z the deenergization 2,168,880. :is maintained in its restoredposit'io'n .so lthat the f .signal device 281 is prevented from-ringing.

From the foregoing description it will readily c'be .apparent that the call as initiated at the station 350 .maybe answered ateither or both of `.the stations .|00 and 20|).- If the call is simultaneously answered at each of thesetwo stations, the relay R230 at the station 200 functions immediately to cause the restoration .of R2|0 and of the signal device 2181, and 'the relay-R|30l at the station |00 functions to cause the vimmediate restoration of Rl |0 and the .deenergization of the signal device |81. The operation of each of theY relays R|`30. and-R230 .causes the associated transmitter and receiver to be connected to the conductors of the line circuit.

The release of a talking connection as established in the manner described above is dif- .,ferent dependingv upon which of the stations |00 Thus, if it at .the staand 200 is the answering station. be assumed that thecall is answered tion 200, the relay R230, upon operating, immediately completes the above-traced holding circuit for itself, which circuit extends from ground at RA3|| of the operated relay R340.. Since R3|0 is no1'l deenergized until the connection is released` at .the kstation 350, the relay R230 will beheld operated independently of its .operating while the .push button 353 isr still depressed, the transmitter 242 and the Vreceiver 24| atv the station 200remainconnected to the line circuit section 204 by virtuefof the continued energization yof R230. When, however,

the push button 363 is released, the operating circuit for R3 |0'is opened at the springs364 causing this relay to restore. Upon restoring,R3|0 reprepares, atRA3l2, the operating circuitfor R320; opens, at RA3| 2 and RA3|5 and their respective associated armatures RA3|3 and RASIB, a point in the talking connection, as described above; and interrupts, at RA3| a point in the above-traced holding circuit for R230. If the push button 243 has been released prior to the. release yof the push button 363, the relay R230 now restores to disconnect,

24| andv the transmitter conductors. 205. and 200 At its armature restoring, repre pares thev operating circuitlforRZlll. Following this operation, the connection is entirely released and the Systemis in'connection for further use in connection vwith another call.

If the calll is answered at the station '|03 and the answering party releases the push button |43 before the callingk partyreleases the push. button 353, therelay R|33 restores to disconnect the transmitter |42 and the receiver |45 fromacross the conductors of the line section |34, and to reprepare, at RA|33,the operating circuit for R| lil. releases the .push button 353 to open. the operating circuit for R3! @,this last mentioned relay restores to open a point in the talking circuit; to reprepare, at RA3l2, the operating circuit for R320; and to interrupt, at RAS! l, a point in the holding circuit for R233; TheA relay R233 now restores to disconnect, at RAZSH, the transmitter 242 and the receiver 24 Yfrom across theconductors of the line circuit section 234 ,and .to reprepare, at RA233, the operating circuit for R25 0. Thus, the connection is completely released.

It will be apparent that, if the call is answered at RA23|, thereceiver 242 from across the of the line circuit section 204.

, at the station i'and the calling party at the ground as applied Thereafter,'and whenthe calling partyV station 37505releases the push button 333 before the answering 4party releases the push button |43, the order of the operations is the reverseof that just described. -More specifically, when the button 363 is released, the operating circuit for u R3|0 is interrupted at the springs 364 whereupon thisrrelay restores to open the holding circuit for R230. Thereafter and when the push button |43 is released, the operating circuit for -Rl30 is opened at the springs |44 and this relay restores. It is apparent, therefore, that the release of the connection as established between the stations .|03 and 350 is in no way affected by the order in which the push buttons |43 and 363 are released.

The operation "of the apparatus following the initiation. of a call at the station 300 is identical that just described insofar as the apparatus at the stations 33 and 200 is concerned, but differs therefrom in-that the apparatus at the station 333 is locked out and the apparatus at the station 533 is connected .to the line circuit. Thus, when the push button 333 is depressed to initiate a call at the station 303, a circuit is completed for energizing R323, this circuit extending from of the switch springs 333, the conductor 327i', RA3|2 and through the winding of R323 to battery. The relay R323 now operates and, at RA32l, applies ground to the conductor 3|8, thereby to cause the energization and operation of both of the signal .devices E87 and 231 located, respectively, at the stations |00 and 200, in the exact manner set forth above. At its armatures RA322 and RA325, the relay R320 connects the conductors 323 and 333 to the respective terminals of the repeater transmitterl 332v and the receiver `33| are connected across this winding Yto prepare a talking circuit to one or both of the 4two stations .Stil and 200. At RA323 and-RASEthe relay opens pointsin-the aboveftraced operatingcircuit ior R3t0', whereby this relay is preventedrom oper.- ating in response to actuation of the push button 333.50 long as the push buton333 pressed. At RA323and forming the line. circuit nectedirom the repeater coil k343.

The modev of operation of thel apparatus provided `at thestations v|33 and 230..:Eollowingthe initiation of a callat'the station .330 is, as wasy pointed .out above, exactlyfthey same as that .set

forth previously with reference to a call initiated at the station30, and` this is true irrespective the station 200, or both. Also, vthe mode of dis connecting the apparatus l.from theline circuit to release the equipmentcr furtheruse is similar to that describedabove, differingtherefrom only in that ground is removed from theconductor 3! 3 to open the holding circuit for R233. following .the release of the push button 333 to open the operating circuit for R323,V When R320 restores, it not only removes ground from. the conductor 3i 3, but also disconnects the receiver 33H and the transmitter332 from across the winding33l 332 of the repeating coil 343 and repreparesthe operating circuit forR3 0, so. that the last-mentioned relay may be energized in kresponse, to the ,initiation of a call at the station 350.

As indicated above, it is possible for two of the train attendants to hold intercab communication in either of the two locomotive cabs. Thus, a trainman at the station ldmay initiate a call directly to the ,station |30, without in anyway aiecting the apparatus located atthev other statothe conductor 3&6 byV Way l coil winding 34H, 332, whereby the tions, by actuating the push button |15 of the manually operable switch comprising the springs |16. This operation serves to complete the operating circuit for the signal device |81, which circuit extends from ground as applied to the conductor |62 by way of the switch springs |16, the conductor |64, the winding of the operating magnet |89 and the contact springs |88 to battery. The resulting operation of the signal device |81 gives an audible indication that the station |00 is being called. The call is answered at the station |00 in the usual manner by depressing the push button |43 to complete the above-traced circuit for energizing the upper winding of R|30. The relay R|30 now operates to connect, at RA|3|, the receiver |4| and the transmitter |42 of the hand set |40 across the conductors |05 and |06 of the line circuit section |04. At RA|33, the relay R|30 opens a point in the operating circuit for R||0, whereby the signal device i81 is prevented from being energized in response to the initiation of a call at one of the

stations

Since, as was pointed out above, the apparatus located in the second locomotive cab is identical in all respects with that provided in the first locomotive cab, it will be understood that a connectionmay be established between the

stations

200 and 250 on a call from the latter to the former and, further, that the operations involved in completing and releasing such a connection are identical with those just described with reference to the establishment of a connection on a call from the station |50 `to the station |00.

The initiation of a call to the station 200 located in the second locomotive cab from the station |00' located in the first locomotive cab involves the use of the non-locking key switch |80. More specifically, when this switch is operated to its off-normal position, a simplex circuit is completed for energizing R220, one branch of this circuit extending from ground on the conductor ||1 by way of the switch springs |84 and |85, the winding IBI, the conductor |05, the Winding 293, the switch springs 282 and 283,

the conductor 2|9, RA2l2, RC2|3 and through the winding of R220 to battery as applied to the conductor 2|5. The other branch of this circuit is similar to that just described, but extends by way of the winding |92, the conductor |06, and the winding 294 rather than by way of the winding |9|, the conductor |05, and the winding 283. The relay R220, upon operating, completes, at RA22|, the above-traced alternative operating circuit for the signal device 281, which device now operates to give an audible indication that the station 200 is being called. Following operation of the switch in accordance with the coded ring identifying the station 200', this switch ls released to interrupt the above-traced operating circuit for R220, whereby this relay is caused to restore to open the operating circuit for the signal device 281. A talking connection is established by depressing the two push buttons |43 and 243. When the button |43 is depressed, the above-traced operating circuit for R|30 is cornpleted at the switch springs |44, causing this relay to operate to complete, at RA|3|, the path for connecting the receiver |4| and the transmitter |42 across the conductors of the line circuit section |04. When the push button 243 embodied in the hand set 240 is depressed, the operating circuit for R230 is similarly completed at the springs 244, whereby this relay is caused to operate to complete, at RA23I, the path for connecting the transmitter 242 and the receiver 24| of the hand set 240 across the conductors of the line circuit section 204. So long as the two push buttons noted are held inV their respective depressed positions, a talking circuit is completed between the two stations |00 and 200, which circuit specifically comprises the line circuit section |04, the repeating coil 290', and a portion of the line circuit section 204. In order to release a connection as set up in the manner just described, it is only necessary for the two parties to release the two push buttons |43 and 243, thereby to open the respective operating circuits for the relays RI 30 and R230. When these relays restore, the transmitters and receivers embodied, respectively, in the two hand sets located at the respective stations are disconnected from the line circuit and the apparatus is in condition for further use.

The operation of the apparatus to set up a talking circuit Y between the two stations |00 and 200 on a call from the latter to the former is, in general, quite similar to that set forth in the preceding paragraph. In this case, however, the non-locking key switch 280 is operated to its olf-normal position to eiect operation of the signal device |81 located at the station |00. When this key switch is moved to its off-normal position, a simplex circuit is completed for energizing RI ||0, one branch of this circuit extending from ground on the conductor 2|1 by way of the switch springs 28| and 282, the winding 283, the line conductor |05, the winding |9|, the switch springs and |86, RA|33, and through the winding of RI |0 to battery as applied to the conductor ||5. The other branch of this circuit is similar to that just described, but extends by way of the winding 294, the line conductor |06 and the winding |82 rather than by way of the winding 293, the conductor |05 and the winding |9|. When RI |0 operates, it completes, at RAI the above-traced alternative operating circuit for the signal device |81 causing this device to give an audible indication that the station |00 is being called. The talking circuit between the two stationsis identical with that briefly described in the preceding paragraph and is completed in the same manner, namely, through the operates it opens, Aat RA|33, a point in the ab0-ve-;

line conductors

205 and 206 is opened at RA23|. From the foregoing description, it will be apparentthat the position of the two locomotives may be transposed without in any waydisrupting the operation of the systenror in any way modifying its mode of operation. the locomotive having embodied therein the apparatus illustrated in Fig. 2 may be employed as the rst locomotive and the'locomotive having embodied therein the apparatus illustrated in Fig. 1 may be employed as the second locomotive.

In this case, however, the line circuit section |0| will effectively be connected in the line circuit and the line circuit section |04 `will be opencircuitedin the exact manner illustrated for the section |0I. Otherwise, the apparatus located at the station 200 will operate Vin the manner set forth above with reference to the apparatus located at the station |00, whereas-the apparatus at the last-mentioned station will operate in the exact manner set forth above with reference to that located at the station 200.v

While there has been described what is at present considered to be the preferred embodiment of the invention, it Vwill be understood that various modifications may be made therein, and it is contemplated to cover in the appended claims all such modifications'as fall within the vtrue spirit and scope of the invention.

I claim:

l. In'a signalling system, a plurality of signallingl stations,U a linel circuit interconnecting said stations, a signal device at each of certain of said stationsa switch at each of said stations, means responsive to the operation of one of said switches forr causing the energization oi all of said signal devices,rand means responsive to the operation of another of said switches for causing the deenergization of Vall of said signal devices.

2. In ay telephone system, a plurality of telephone stations each comprising a transmitter and a receiver, a line circuit interconnecting said stations, a signal device at each oi certain of 5, said stations, a switch at .each of said stations,

each of said switches being operative to connect the associated transmitter and receiver to said line circuit, means responsive to the operation of one of said switches for causing the v energization of a plurality of said signal devices,

and means responsive to the operation of another of said switches for .causingthe deenergiza-v tion of; said .plurality of signal devices.

3..In atelephone system, a plurality of tele- .phone stations each comprising a transmitter More specically,

and a receiver, a line circuitinterconnecting said stations, a signal device at each of certain. of said stations, a switch at .each of said stations, each of said switches being operative to connect the associatedy transmitter and receiver to said line circuit, means responsive to the operation ofthe switch at a particular calling one of said stations for causing Vthe energization of all of said signal devices, and means responsive to the operation of the switch at an answering one of said stations for causing the deenergizaticn of all of said signal devices.

4. In a telephone system, a plurality of telephone stations each comprising a transmitter and a receiver, a line circuit interconnecting said*r means responsive to the operation of the switch at a particular calling one of said stations for preventing the transmitter and receiver at a second of said stations from being connected to said line circuit, means also responsive to the operationgof said last-named switch for causing the energization of yallof said signal devices, and means responsive to the operation of the switch at an answering one ofI said stations for causing the deenergization of all of said signal devices.

5. Ina telephone system, a plurality of telephone stations each-comprising a transmitter and a receiver, a line circuit interconnecting said stations, a signal device at each of certain of said stations, a switch at each of said stations, a relay at one of said stations operative in response to the operation of the associated switch for connecting the associated transmitter and receiver to said line circuit, an operating circuit for said relay, means at each of the other stations controlled by the respective associated switches for connecting the respective associated transmitters and receivers to said line circuit, a lockout relay cuit in response to the operation of the switch at a particular calling one of said stations, means responsive. to the operation of said lockout relay for causing the energization of. all of said signal devices, and means responsive to the operation of the switch at an answering one of said stations for causing the deenergization of said signal devices.

6.In a telephone system, a plurality of telephone stations each comprising ka transmitter and a receiver, a line circuit interconnecting said stations, a signal device at each of certain of said stations, a switch at each of said stations, a relay at one of said stations operative in response to the operation of the associated switch for connecting the associated transmitter and receiver to said line circuit, an operating circuit for said relay, means at each of the other stations controlled by the respective associated switches for connecting the respective associated transmitters and receivers to'said line circuit, a lockout relay operative to open a point in said operating circuit in response to the operation of the switch at a particular calling one of said stations, a plus rality of relays each associated with. one of saidV 4cause the deenergization of said 5 operating circuit of 5 for preventing 70 said line sively energized in response to the operation of said lockout relay, and means responsive to the operation of a switch at an answering one of said stations for altering said circuit connections to plurality of relays.

7. In a telephone system a pair of telephone stations each comprising a transmitter and a receiver, a line circuit interconnecting said stations 10 and comprising a plurality of conductors, a manually operable switch at each station, means at each station controlled by the associated switch for connecting the associated transmitter and receiver to the conductors of said line circuit, a

signal device, a second manually operable switch at one of said stations, a circuit independent of said line circuit and including contacts embodied in said second switch for energizing said signal device, an alternative circuit for energizing said zo-signal device, a relay at the other of said stations operative to complete said alternative circuit, and means responsive to the operation of the switch at said other station for preventing said relay from operating to complete sald alternative cirl Cuit.

lrelay at each station including contacts for connecting the associated transmitter and receiver to the conductors of said line, an operating circuit individual to each relay, a manually operable switch at each station for completing the the associated relay, a signal device at one of said stations, a second manually operable switch at the other of said stations, a circuit independent of saidline circuit and including contacts embodied in said second switch Oilfor energizing said signal device, an alternative circuit for energizing said signal device, a second relay at said one station and operative to complete said alternative circuit, and means comprising the iirst-named relay at said one station said second relay from operating to complete said alternative circuit when the transmitter and receiver` at said one station are connected to the conductors of said line circuit,

9. In a telephone system, a pair of telephone stations each comprising a transmitter and a receiver, a line circuit interconnecting said stations and comprising a plurality of conductors, a manually operable switch at each station, means at each station controlled by the associated switch 5 for connecting the associated transmitter and receiver to the conductors of said line circuit, a signal device, a second manually operable switch at one of said stations, a circuit independent of said line circuit and including contacts embodied .in said second switch for energizing said signal device, an alternative circuit for energizing said signal device, a relay at the other of said stations operative to complete said alternative circuit, an operating circuit for said relay, said operat- 65ing circuit including at least one of said line conductors, means responsive to the operation of the switch at the other of said stations for preventing said operating circuit from being completed, an additional telephone station associated with circuit, and a switch at said additional station operable to complete said operating circuit only when the switch at said other station is not operated.

10. In a telephone system, a pair of telephone 75 stations each comprising a transmitter and a receiver, a line circuit interconnecting said stations and comprising a plurality of conductors, a manually operable switch at each station, means at each station controlled by the associated switch for connecting the associated transmitter and receiver to the conductors of said line circuit, a signal device,A a second manually operable switch at one of said stations, a circuit independent of said line circuit and including contacts embodied in said second switch for energizing said signal device, an alternative circuit for energizing said signal device, a relay at the other of said stations operative to complete said alternative circuit, an operating circuit for said relay, said operating circuit including at least one of said line conductors, means responsive to the operation of the switch at the other of said stations for preventing said operating circuit from being completed a pair of additional telephone stations associated with said line circuit, a manually operable switch at each of said additional stations, the switch at one of said additional stations being operative to complete said operating circuit only when the switch at said other station is not operated, and means responsive to the operation of the switch at the other of said additional stations for completing said alternative circuit independently of the position of the switch at said other station.

l1. In a telephone system, a pair of telephone stations each comprising a transmitter and a receiver, a line circuit interconnecting said stations and comprising a plurality of conductors, a manually operable switch at each station, means at each station controlled by the associated switch for connecting the associated transmitter and receiver to the conductors of said line circuit, a signal device, a second manually operable switch at one of said stations, a circuit independent of said line circuit and including contacts embodied in said second switch for energizing said signal device, an alternative circuit for energizing said signal device, an additional telephone station associated with said line circuit, a manually operable switch at said additional station, and means responsive to the operation of said last-named switch for completing said alternative circuit.

12. In a telephone system, a pair of telephone stations each comprising a transmitter and a receiver, a line circuit interconnecting said stations and comprising a plurality of conductors, a manually operable switch at each station, means at each station controlled by the associated switch for connecting the associated transmitter and receiver to the conductors of said line circuit, a signal device, a second manually operable switch at one of said stations, a circuit independent of said line circuit and including contacts embodied in said second switch for energizing said signal device, an alternative circuit for energizing said signal device, a relay at the other of said stations operative to complete said alternative circuit, an operating circuit for said relay, said operating circuit including at least one of said line conductors, means responsive to the operation of the switch at the other of said stations for preventing said operating circuit from being completed, an additional telephone station associated with said line circuit, a switch at said additional station, and means responsive to the operation of said last-named switch for completing said alternative circuit independently of the position of the switch at said other station.

13. In a telephone system, a telephone station comprising, in combination, a signal device, a transmitter, a receiver and a manual-ly operable switch, a line extending'to said station and including a pair of conductors, a relay operative in response to the application of a predetermined potential to one of said conductors to cause the energization of said signal device, and means comprising a second relay operative in response to the operation of said switch for causing the de'energization of said first-named relay and for connecting said transmitter and receiver to said line.

14. In a telephone system, a telephone station comprising, in combination, a signal device, a transmitter, a receiver and a manually operable switch, a line extending to said station and including a pair of conductors, a circuit for energizing said signal device, a relay operative to complete said circuit, an operating circuit for said relay, said operating circuit, including one of the conductors oi said line circuit and being adapted to be completed when a predetermined potential is applied to said one conductor, a second relay operative in response to the operation of said switch to connect said transmitter and receiver to said line, and contacts controlled by said second relay for interrupting the operating circuit for said first-named relay when said switch is operated.

15. In a telephone system, a telephone station comprising, in combination, a signal device, a transmitter, a receiver and a manually operable switch, a repeater comprising a pair of windings, a line extending to said station, said line including a pair of conductors respectively connected to the terminals of one of said windings and a pair of conductors respectively connected to the terminals of the other of said windings, means responsive to the application of a predetermined potential to one conductor of one of said pairs of conductors for causing the energization of said signal device, means responsive to the application of said predetermined potential to one conductor of the other of said pairs of conductors for also causing the energization of said signal device, and means responsive to the operation of said switch for causing the deenergization of said signal device only when energized through theoperation or said rst-named means.

16. In a telephone system, a telephone station comprising, in combinaton, a signal device, a transmitter, a receiver and a manually operable switch, a repeater comprising a pair of windings, a line extending to said station, Said line including a pair of conductors respectively connected to the terminals of one of said windings and a pair of conductors respectively connected to the terminals of the other of said windings, means responsive to the application of a predetermined potential to one conductor of one of said pairs of conductors for causing the energization of said signal device, means responsive to the application of said predetermined po-tential to one conductor of the other of said pairs of conductors for also causing the energization of said signal device, means responsive to the operation oi said switch for causing the deenergization of said signal device only when energized through the operation of said rst-named means, a second manually operable switch at said station, said second switch being operative to apply said predetermined potential to one of the conductors of said one pair of conductors without causing the operation of said signal device.

17. In a telephone system, a plurality of telephone stations each comprisingY a transmitter and a receiver, a line circuit interconnecting said stations, a signal device at each of certain of said stations, .and control apparatus located at each of said stations.; said control apparatus, said signal devices, and said line circuit being so connected and arranged that all of said signal devices may simultaneously be energized from certain of said stations, said signal devices may selectively be energized from others of said stations, and talking connections including said line circuit may be established between at least a portion of said telephones.

18. In a telephone system, a plurality of telephone stations each comprising a transmitter and a receiver, a line circuit interconnecting said stations, a signal device at each of certain of said stations, at least one switch at each of said sta.- tions, and control .apparatus located at each of said stations; said control apparatus, said signal devices, said line circuit and said switches being so connected and arranged that all of said signal devices are simultaneously energized in response to the operation of certain of said switches, said signal devices are selectively and individually energized in response to the actuation of others of said switches, and talking connections including said line circuit may be established between at least a portion of said telephones.

19. In a telephone system for use on board a train comprising a plurality of interchangeable vehicles, a pair of telephone stations in each of certain of said vehicles, a single telephone station in each of others of said vehicles, said stations being adapted to be interconnected by a line circuit extending therebetween and each comprising a transmitter, a receiver and control apparatus; the control apparatus, the transmitter and the receiver at each of the two stations in each vehicle having a pair of stations being so connected and arranged that the positions of the vehicles having two stations may be interchanged -in the train without interfering with the operation of said system.

20. A train telephone system comprising a terminal station located at one point on the train, a plurality of telephones located at other and different points on said train, a line circuit extending through the train and adapted to interconnect said telephones and said terminal station, a signal device at said terminal station,

a switch associated with one of said telephones.,

means responsive to operation of said switch for connecting said one telephone to said line, andv means also responsive to operation of said switch for causing the operation of said signal device.

21. A train telephone system comprising a terminal station located at one point on the train, a plurality of telephones located at other and different points on said train, a line circuit extending through the train and adapted to interconnect said telephones and said terminal station, a signal device at said terminal station, a switch associated with one of said telephones, means responsive to operation of said switch for energizing said signal device, and means also responsive to operation of said switch for preventing any telephone other than said one telephone irom being connected to said line.

22. A train telephone system comprising a terminal station located at one point on the train, ,a plurality of telephones located at other and different points on said train, a line circuit extending through the train and adapted to interconnect said telephones and said terminal station, a signal device at said terminal station, .a switch associated with one of'said telephones, means responsive to operation of said switch for connecting said one telephone to said line, means also responsive to operation of said switch for causing the operation of said signal device, and means also responsive to operation of said switch for preventing any telephone other than said one telephone from being connected to said line.

23. In a telephone system for use in a train comprising a plurality of interchangeable vehcles, a plurality of telephone stations in each of at least a portion of said vehicles, said stations being adapted to be interconnected by a line circuit extending therebetween and each comprising a transmitter, a receiver and control apparatus; the control apparatus, the transmitter, and the receiver at each of the stations in each vehicle having a plurality of stations being s0 connected and arranged that the positions of the vehicles having a plurality of stations may be interchanged without interfering with the operation of the system.

EDWARD S. PETERSON-