US1224374A - Two-way, two-wire trunk for multi-office automatic exchange systems. - Google Patents

Description

C. L. GOOURUM.

TWO-WAY, TWO-WIRE TRUNK ron MULTI-OFFICE AUTOMATIC IXCHANGE SYSTEMS.

APPL!CATION FILED DEC-5| I914- HENEWED MAR. 3 I911- 1,224,374.

Patented May 1, 1917.

lflvenfar C/mr/e s L. good/11m. y a

UNITED STATES PATENT OFFICE.

CHARLES L. GOODBUM, OF NEW YORK,, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CO RPORATION OF'NEW YORK.

TWO-WAY, TWO-WIRE TRUNK FOR MUL'II-OFFICE AUT( MA'I'IC EXCHANGE SYSTEMS.

Application filed December 5, 1914, Serial No. 875,579.

provide a two-way trunk having an llllproved and con'iparatively simple arrangement of circuits and. apparatus. One ohject in ]')a-rtienlar is to provide a two-way trunk in which interference with the circuits by varying ground potentials hetween otliees, is avoided.

In accordance with the invention, the trunk circuit is connected at hoth central otfices through repeating coils to the multiple bank of an outgoing selector, and also to the brushes ot-an incoming selector. (Jails at. one end of the trunlcenter at the bank ter minals of the outgoing selector and are extended beyond the other end by the incomin selector at that end] A relay at each endol the trunk controls the connection of the trunk to either the bank terminals or the selector brushes at that end. The circuit established liet-wecu'the outgoing selector at one end of the trunk and the .incoming selector at the other end. includes battery and ground at. one end only oi the trunk, whereby interference with the circuit byyvarying ground potentials between the ofiiecs connected by the trunk is avoided.

The invention may he more readily understood by reference to the accompanying drawing of a systemembodying the invention.

Referring to the drawings, the two-wire two-Way trunk tern'iinates at the central oflice A in the [multiple bank of an outgoing selector 1 at lat the central ollice l in the brushes oi incoming selector 2. For example, a call from the subscribers station C for a called subscriber I), entering the office A, arrives at the bank terminals of the outg'oing selector 1 and is extended heyontlthe other oflicc B the incoming se Specification of Letters Patent.

v Hatented May 1, 1917.

Renewed It arch 3 1917. Serial No. 152,434.

letter 2. li the opposite direction, calls over the. sani trunk arrive at the bank ternunals of an outgonig selector? at the ollice B, and are (Xl(llll(ll beyond the station by ineans oi the incoming selector Thus a call l'roni the subscribefis station [Q for a called subscr her l will enter the ollice l at the hank terninals ol' the outgoing selector 3 and will ie extendcdlrv the incoming selector 4 at the olliee ll will he seen, therefore, that at each end of the trunk there is an outgoingand an incoming selector, and tl at the outgoingselector at one end cooperat s with the incoming selector at the other end to extend a call.

At each e| d, the connection of the trunk to either the outgoing or the incoming selector is not er the control of a relay. the relay 5 at ollice A, and the relay (1 rid. olliee B. Nor-mall" the trunk iseonuected at both ends to the ineoining selectors. at ollice A. through bacl; contacts 7 and h of relay '5 and repeating" coil 9 to the brushes ol the selector-l, an I at ollice ll through hack contacts l0 and l of relay-(5 and repeating coil 12 to the bru ihcs of the selector 2.

The relay .i' is included in a third wire 13' local to the llice A, and the relay (i is |il ewise includel in a third wire l-l local to the. ollice l3. call entering. l'or example. at the bank terminals ol the selector 1 results in the encrglzation,ol' the relay which thereupon dirconnects that end of the trunk from the seltctor 4. and connects it through front contacts 15 and ll) of relay 5 and repeating coil 7 to the outgoing selector I.

When a ca l is being, extended from either ollice over tlu trunk line, a relay at the other Ollie-e, relay l8 at ollice ll or relay .ll) at. ollice A, resp lads, and through circuit connections cont ollcd hy it over the third wire, renders the trunk 'busy at said other ()lllctL, The operat on of the system is as follows: Assume that the subscriber at C, whose line terminates a ollice A, desires to call the suhscribenat 1) whose line' terminates at olliec ll. Th: suhscribefls telephone line is extended in he usual manner through the line tinder 2|! and the brushes ollhc outgoing seleeto- 1 to an idle trunk, the. two wires 21 and 22 of which areconucctml to the contact t1 :ri'ninals of selector 1. Thereupon, a circlitis closed for the relay 5 as follows: from ground, through trunk relay 23, wire 13, relay 5, battery 24 to ground. The resultant energization of relay 5, opens contacts 7 and 8 and closes con tacts 15 and 16,'thereby disconnecting the two wires 25 and 26 of the trunk from the selector '4 and connecting them to the outgoing selector 1. Though the trunk relay 23 is included in the circuit closed over the third wire 13, said relay does not operate, since it is a marginal relay and the windings of relay 5 are of such high resistance that the. current flow in the circuit of the third wire is insufficient to operate the relay 23.

The subscribers line being extended from station 0 to selector 1, a circuit is estab lished for a relay 27, as follows: from batte .24,'rela 27 wire 21, contact terminal an brush 0 selector 1, wire 28 of the telephone line, the subscribers tele hone set,

, brush and contact terminal of selector 1, wire 22, to battery. The resultant'operation of relay 27 closes contacts 30 and 31 of said relay. The closure ofcontact 31 controls the flow of current for the actuation of relay 23 for the. purpose of releasing the selector 1, as will be hereinafter described.

The above mentioned closure of contact 30 establishes an operating circuit from oflice A to ofiice B over the trunk, as follows: from battery 24 at oflice B, through contacts30 and 15, wire 25, contact 10, relay 18 contact 11, wire 26, contact 16 to battery. Thereupon relay 18operates, closing its contacts 32- and 33. The closure of contact 32-completes a circuit for a relay 34," which is thereu on actuated and, through. its contact 35,,p aces round upon the third wire 14, thereby r'e'n ering the trunk busy at oflice B. r v

The closure of contact 33 of relay 18 com- 'pletes the operating circuit for the incomin selector 2 over the wires 36 and 37 whic are connected to the brushes of said selector.

Circuits are thus established for extending the connection from the incomin selector 2 at office B to the called subscrfimers station D. That is, the calling subscriber at'station C, by operatin his dial, inter- .ru ts the above describ circuit through re ay 27. There is, therefore, a corresponding lnte'rruption of the circuit over the trunk wires 25 and 26 at contact 30 of relay 27. In turn, there is a corresponding interruption of the circuit of selector 2 at contact 33 of relay 18. The selector 2 andconnector 38 may thus be actuated in the usual manner from the dial at station C, to extend the connection to the called subscriber at station D. TlIQ'tWO wires 25, 26 of the trunk line being inductively connected through the repeating coil 17 at oflice A with the callin line, and also being inductively 'connecte through the repeating coil contact 31 of relay 27 is to establish a releasing circuit for selector 1 when the callin subscriber hangs up his receiver. This wi 1 now be described. The closure of contact 31, at the time the subscriber at station 1C removes his receiver, completes a circuit for a .slow-actin relay 39. The resultant operation of sa-i relay closes its contact 40, thereby completing a circuit for another slow-acting relay 41, which thereupon closes its contact 42. Relays 39 and 41 bein of the slow-release type, do not respond to interruptions of the circuit at contact 31 by the operation of the calling subscribers dial. However, when contact 31 is opened by the subscriber hangin up his receiver, relay 39 is released and c oses its ck contact 43. Relay'41 being of the slow-release type, maintains its contact 42'closed for an appreciable time after contact 43 is closed, durin which interval operating current is su plied to the marginal relay 23 over the f0 lowing circuit: from grounded battery,

.through contacts 43 and 42, wire 13, relay 23, to ground. Relay 23 thereupon responds to close the circuit of release magnet 44 of selector 1. It will be understood that the structure, operationand circuit connections of the several switches at each end of the trunk may be of an usual or known type and hence further i lustration and description thereof is deemed unnecessary.

What is claimed is:

1. In an automatic telephone exchange system, a two-wire trunk extending between two central ofiices, an outgoin and an incoming selector for said truni at each of said oflice's, and automatically operated means for completing in either direction a battery connection to said trunk at one oflice and a connection free of batte to the incoming selector at the other 0 cc.

2. In an automatic telephone exchange system, a trunk-extending between two central olfices, selecting apparatus and a battery for said trunk at each of said oflices, and

means operating automatically in'setting up a connection through said trunk in either direction for closing the trunk to battery at one end, and for maintaining it as a closed loop free from external connections with 1 battery. at the other end.

3. In an automatic telephone exchange As hereinbefore stated, the function of 70 ing end, and, for maintaining it as a clos loop free fif'om external connections with batter'y at the incoming end.

4. In an automatic telephone exchange system, a repeating trunk extending betwem two central offices, selecting apparatus and a battery for said trunk at each of said ofiices, said trunk being normally maintained at each end as a closed loop tree from connections with battery, means operating. automatically in setting upa connection to said trunk at either office for closing the trunk to battery at one end and for maintaining the normal condition thereof at the other end, and means for interrupting the trunk at the outgoing end to repeat calling impulses to control the selecting apparatus at the incomin; end of the trunk. Q

In an automatic telephone exchange system. a two-wire trunk between two central ofiices, an outgoing and an incoming selector for said trunk at each of said oflices, a

local circuit at each oilice including multiple hank contacts of an outgoing selector and battery, a second local circuit at each ofiice' including brushes of an incoming selector, two connecting circuits at each oflice inductively connected, respectively, to said local circuits. and autrmlatically operated means at each ofiice for controlling the connection of the trunk line to one or the other of said connecting ci :cuits at the respective offices.

6. In an automatic telephone exchange system, atw( Wire trunk between two central offices, an outgoing and an incoming selector forsaic tru'nk at each of said oiiices, a local circuit at each office including multiple bank contacts of an'outgoing selector and necting circuits, and automatically operated means at each office for disconnecting the trunk from tle incoming selector and trans fer-ring the c mnection, over the other connecting and local lector.

In witness whereof, I hereunto subscribe my name the 3rd day of December A. D.,

CHARLES L. GOODRUM. Witnesses E. E01 ER,

.K. L. E ram.

circuits, to the outgoing'se-

Images