US1804822A - Telephone system - Google Patents

Description

May 12, 1931. J. 1. BELLAMY 1,804,822

TELEPHONE SYSTEM Original Filed June 15. 1928 g II I :2. 65 Q: n IE 1 L i s m 5} z *1 r l3 i 1 a L J IrFeTiT:1T-'

' Jahn-LBaZZgmH Patented May 12, 1931 JOHN i. BELLAMY, on nnoonnrnnn, rumors, essrenon T0 RESERVE nonmne com- PANY, or KANSASCITY, srrssoonr, A CORPORATION on DELAWARE .rnnnenonn 's-Ys'rmvr Application filed Juney1328, Seria1*l\'|"o.285,530. Renewed May-24, 1930.

T he present invention relates to telephone systems in jgenerah'thatis concerned more particularly with telephone systems using non-numerical switching apparatus; andthe 5 main object is the production of: new'and improvedarrangements 1 whereby the operation ofth'e so-called plunger-type secondary, non- :numerical' line switches is rendered more satisfactory.

The present invention hasbeen applied to secondary lineswitches of the plunger type used in airautomatictelephone system bei tween one level of the banks of aigroup of automatic'selectors anda. groupioi' trunk lines divided intosub groupsas regards the level 111- question and each sub group has accessto ten trunlrsextending to secondary line 4 switchesin several groups, each secondary line switch group being controlled bya separate master switch andhavingiaccess to a separate sub group of ten outgoingvtrunk lines. g

Although arrangements as outlined above have eenemployed commerciallyfor many years; and-have proven highly satisfactory, an outstanding detect hasEbeen present. This'defect lies in thearrangements provided for rendering the incoming trunks busy to the remaining secondary lines-witches of v a sub group when one of them is seized. The result isthat one or more additional'line switches are often seized and perhaps operated before the remainingtrunksare made busy to the selected switches having access to them, "This'resu'lts in lost calls owing to the tact that two switches often seize thesame trunk. andowing to the'fact thatthe second connection has often released by the time the master switch finds an idle trunk in casethe last seized secondary switchwas seized too late to be operated before the battery potential is removed from the so-ca'lled openhe no further calls should be permitted to come I into the secondary group because. such line switch: takes the last remaining idle trunk.

v Keeping 'in mind the defects Outlined above, the specific. object Of the presentin- 1 ventien is the productionof suitable circuit arrangements 'for rendermgallthe rema1naingidle trunk lines busy in a secondary sub groupwhen one of thenris seizeduntilthe seized lineswitch has operated zand the master switch has located a new-idle trunkline.

Accordingly, the circuit arrangements have .-placin'g:oi i a ground potential onaany: one: of

them seized by a selector renders the; entire sub group busy, arrangements being provided 'forremoving the busy condition only after the seized line switch has operatedand the master switch has found another idle trunk line. By this arrangement, if the: trunk seized is the last-idle one in a group, the masterswitch; is unable to find another idle trunk line and the .busy condition-is maintain-ed on theremainwing idle trunk incoming lines until such time as another outgoing trunk: line becomes idle and is preselected. It: illbe understood of ;.'course,. that while one subgroup of trunk li-nesis,=-busy the callsare routedaby the contain idletrunk lines.

' Referring now, to the drawings comprising :Figs-l and 2, Fig. l'shows a trunk line comprising conductors 2,3, and 4, and leading from the banksof selectors (not shown) tothe secondary line switch SLS. --The repeaterR, which is one ct -the ten-repeaterstowhich the, secondary line 7 switch SLSzhas access :in common with other secondary line switches,

is shown interposed between .theline switch I banks and the outgoing conduotorsg27and 28, according tostandard practice. A. portionzof :tlie master sswitch which :presides (,OVGI thesaidgroup'conta-ining the secondary line switchSLS has been shown in the lowerpartt ot thedrawing, as well as the control groupof relays common I to the sub :group (,of line switches. The secondary, line-switchisarranged through the cooperation 'ofrelays; 5 end 6 to r apply. gr und. potentiallto;releas ,sel-ectors into such other subgroups as may 1 trunk conductor 3 upon the release of the connection for a short interval so as to maintain the trunk line guarded during the restoration of the plunger arm the realignment of the plunger so as to permit the use of the socalled self aligning plungers, which plungers are immediately returned to the control of the master switch without waiting for the master switch to be advanced to where it will pick themu'p again.

' The invention having been described generally, a detailed description of the operation of the'apparatus shown will now be given.

For this purpose it will be assumed that the master switch is standing in the position shown in the drawingwith the trunk line extending to the repeater R preselected and that the idle trunk comprising conductors 24 and extending to the secondary line switch SLS is seized by a selector. When the seizure is made, the calling subscribers loop is extended and placed across conductors 2 and 4 n the usual manner and ground potential is applied by the seizing selector to release-trunk conductor 3. Conductor 3is normally con- I nected through contacts of relays 5 and 6 to guard conductor 39, which is common, as

indicated. to all theline switches of the sub 7 group. Therefore, the placing of ground -potential on conductor 3 extends a ground potential to the similar conductor of each idle line' switch of the sub group, as each idle line switch has its release trunk conductor connected to the common guard conductor 39 in the same way as the trunk shown.

In order to maintain the guarding potential applied to conductor 39, the common relay 34' in the control group energizes over conductor 39 and locks ground on conductor 39 at its'upper contacts through contacts of relays 32 and33, the slow acting relay 33 being normally energized through contacts of relay 34. Relay 34 opens the circuit of the slow acting relay 33, but relay 33 remains operated for a substantial interval, the function'of this'relay being such that it is not required to fall back on every call, as it is provided for a special condition to be hereinafter explained.

' Responsive to the extension of the sub- "scribers loop to the line conductors 2 and 4,

ductor 4 through the lower armature of relay 5. Upon operating, relay 5 looks itself relay 5 whose upper winding is connected to conductor2 energizes over the calling line from the ground potential supplied to coni to release trunk conductor 3 at its inner lower armature and it disconnects release-trunk conductor 3 from the common guard conductor 39 at its inner upper armature and closes a circuit from the grounded conductor 3 through the pull-down winding of the line switch magnet 7 to battery by way of the open-main conductor 38, through normally result of the operation of relay 5 it disconnects its upper winding and ground from conductors 2 and 4, and closes a circuit for the slow-releasing relay 6, which operates and prepares a guarding circuit for the trunk line.

As a result of the extension of theconnection to the repeater R, line relay thereof operates over conductors 21 and 24 from the subscribers loop and closes a circuit for release relay 26 which operates and places a ground potential on conductor 22 which extends back to release trunk conductor 3 of the secondary line switch so as to maintain the secondary line switch and the other apparatus of the connection, including the seizing selector, in an opera-ted condition. As the further result of the operation of relay 25 of the repeater R, a bridge is placed across the outgoing conductors 27 and 28 including the right-hand repeating coil windings, preparing the switch (usually a selector) to which thetrunk line extends in the distant office for operation in the usual manner.

As a result of the depression of spring 10 of the line switch SLS, when the line switch is operated as above described, 'a ground potential is placed on test conductor 23, rendering the trunk line busy to the master switch, with the result that start relay of the master switch operates through test wiper 37, and closes a circuit at its lower armature for driving the master switch away from the busy trunk in search of an idle one. At its upper armature, relay 35 removes battery from the open-main conductor and places a ground potential thereon, closing a circuit for relay 31 of the common control group, which relay operates and closes a new locking circuit for relay 34 at its upper armature, at the same time operating relay 32 at its lowerv armature to open the initial locking circuit.

When the master switch finds an idle trunk as evidenced by the factthat no ground potential is encountered on the test conductor of such trunk line by test Wiper 37, start relay 35 falls back and stops the operation of the master switch by opening its lower contacts. Itremoves the ground potential from the open main conductor 38 and replaces a Q 1 tialhas been removed from the common coninseam battery "potential thereon, wher e'upo'n 'relay 31 of the common grou'p falls back an'd removes the ground otential from thelocking ireuitef reiay 3 l-"and from the guard con- 1 d-uctoi 39, whereupon I relay '34 falls back and opens a further I point in its locking. circuit, at the same timereclosing thecircuit ofthe slow acting relayf33, which relay is usually i'ng -the' test. Relay 31 also opens thercircuit 'pares the initial 1 locking circuit of relay The relative" adjustment o'frelays 32 and 34- issuchthat relay 3 falls back "and opens afurther; point in its locking cireuit 'before re-' -layi32 can fall backandreclosethe initial loeki ng circuit of relay 34.

The master switch has-now selected an otheridletrunk line and the ground potensductor39-so that other calls may benow handle d throughthe saidygroup. It will be understood-of course, that theoperation of preselectingwanother idle trunk andagain -contacts;;of line relay-"of the repeater R over conductors-27-and-28 to set the said switches i'irthe distant office in the usual manner.

lVhen the receiver isreplaced on the calling telephone, relay 25 falls back andjproa armature, whereupon the seizing selector and.

other switching apparatus included in the connect-ion release, and relay 5' ofthe second- I aryline sWitch'SLS'falls back. Uponso doing, relay 5, at its inner upper armature,

closes :a circuit through the operated armature of slow-acting relay 6 toground, reapplyinga-guarding potential to conductor 3 so as to' preverita reseizure ofthe secondary switch during the restoration "and realign 'ment of the'plunger thereof. After sufficient time is allowed for this operation the slow acting relay 6: falls back,in res'pon'seto;

-its-circuit being opened at the-lower armature of; relay 5, and reconnects the conductor 3-. to the common guard conductor 39.

5 Referring again to i the repeater R- and to is a chain circuit for the stop'relay- 36 in the master switch including contacts of relay 26 r and similar contacts'of other relays'suchgas stop relay 36of the inasten switch only when all trunk :linesa cessible to theline switches cuitof relay 34'.

I of the sub group" are 'busy, merely to stop usenecessary drain on "the exchange battery. The-busy' condition is maintained on a sec- 'ondary group because test wiper 3? of 2 the master switch does not encounteran un- Jguarded test contact. Therefore relay 35 is still in anoperatedcondition unless a large:

0 number of trunks have been passed' over durmaintain d operated, with theresult that 'relays 3,1 and3 l- 'are inaintained operated to Regarding the'utility off'the slow acting frelay 33,'it'may' befpointed out that aground "potential'is likely to 'be su'pplied accidentally to one ofthe release trunk conductors, suchas the release trunk conductor 3 of the I secondary line switch SLS, causing relay 34:

tolockup'and hold. a busy condition on the entire sub groupeven after the original ac:

cuit of which opened upon the operation'of relay 34, the locking circuit ofirelay '34 and the busy circuitover conductor 39 isshortly opened removing the guarding potential ate relay '33 to again preparethe locking cir- Referring now tol3ig 2'it will be apparent that the secondary line switch SLS shown therein'is similar in every respect except that no relay corresponding to relay 6 of Fig. 1 is prov'i'ded and that the'back contact of the inner upper-armature ofrelay 5 leads'directly" to the common guard ,conductor instead ofthrough contacts of'a relaysimilar to relay Gas in Fig. 1. This modification is. for use of course wherever the self-aligning plunger'mare not'required and therefore not What is claimed 1. In a telep'hon'e trunking system, a plu ;rality of incoming trunks each terminating in'a'pres'electing switching mechanism, a less- "er' plurality of outgoing'trunks accessible in common to all said mechanisms, means for making busy all idleincomingtrunks whenany incoming trunk is taken for use, n1eans for thereafter operatingthe switching mech- -anism in which theseized' trunk terminates, rn'ea-ns common to all said pr'ese'lecting switching mechanisms forpreselecting another out {going trunk, and means for maintainingthe busy condition'on' the incoming trunks'until the master switch it will be noticed that there said preselecting means has preselected another. trunk.

' 2. In a telephone'system wherein a plurality of non-numerical switching mechanisms are accessible to automaticswitchingappara "tus,-an"d are presided over bya master switch arrangedfto cause all idle "nonmumerical SWitClll11'gmechanisms controlled-thereby to l maintain ground potential on guard con- 7 ductor 39.

froin therelease trunk conductor and permitting relay 34.- to fallback again andreoperpreselect the same idle outgoing trunk, means artifically busy all idle switching mechanisms before the said seized mechanismis operated and for maintaining them busy to said automatic switching apparatus until the said operation of the master switch is performed.

3. In a telephone system wherein automatic switching apparatus has access to non-numerical switches governed by a master switch arranged to preselect an idle one of a plurality of trunks accessible to the non-numerical switches and to presele'ct another idle trunk when the preselected one Is taken for use, means responsive to the seizure of one of said non-numerical switches for making all of them busy simultaneously and for maintaining the busy condition until the preselected trunk has beentaken for use by the seizedswitch and the master switch has operated to preselect another trunk.

4. In a telephone system wherein automatic switching apparatus has access to' non numerical switches governed by a matter switch arranged to preselect an idle one of a plurality of trunks accessible to the non-,

1 numerical switches and'to preselect another idle trunk when the preselected one is taken for use, means responsive to the seizure of one of-said non-numerical switches-for making all of them busy and for maintaining the busy condition until the preselected trunk has been taken for use by the seized switch and the master switch has operated to preselect another trunk, said means including a self locking relay operated over the seized trunk line and unlocked responsive to the operation of the master switch.

5. In a telephone trunking system, a plurality of trunks, means responsive to a seiz ure of oneof said trunks for making all idle ones busy, and means including a progressively movable testing device common to said trunks for removing the busy condition from all of them that are idle. 7

6. In a telephone'system, a plurality of incoming trunks, a plurality of outgoing trunks, switching mechanism for seizing incoming trunks, switching mechanism for connecting seized incoming trunks to idle outgoing trunks, and means common to said incoming trunks and controlled over any one of them for making all idle incoming trunks artificially busy whenever any one of them is seized. V

7. Ina telephone system, a plurality of in-. coming trunks, a plurality a of outgoing trunks, switching mechanism for seizing incoming trunks, switching mechanism for con-.

necting seized incoming trunks to idle outgoing trunks, means common to said incoming trunks and controlled over any one of them for making all idle incoming trunks artificially busy whenever any one of them is seized, and means including a timing device common to all said incoming trunks for rendering idle the artificially busy trunks.

8. In a telephone system, a group of trunk lines, means common to said lines for placing an artificial busy condition on all idle" trunk lines, and means including a timing device common to said trunk lines for removing the said artificial busy condition.

9. In a telephone trunking system, a plus rality of incoming trunks each terminating in a preselecting switching mechanism, a lesser plurality of outgoing trunks accessible in common to all said mechanisms, means for making busy all idle incoming trunks when for thereafter operating the switching mechanism in which the seized'trunk terminates,

means for maintaining the busy condition on the incoming trunks until another trunk is preselected, and means, automatically effective to remove the busy condition at the end of a predetermined time in case the lastnamed switching mechanism fails to operate.

10. In a switching system, a line, an automatic switch arranged to extend said line, a line relay connected to said line and arranged to be energized thereover, an oper ating circuit for said switch controlled by said line relay, a release trunk conductor included in said line, a self-locking circuitfor said line relay including said release trunk conductor, means external to said lineswitch for applying potential'to said release trunk conductor before the lineswitch is operated to prepare the said locking circuit for the line relay, and means external to said switch for removing the locking potential from said release trunk conductor when the connection set up through the switch is to be broken for deenergizing said line relay to permit said switch to release.

11. In a' switching system, an incoming line terminating in a lineswitch, said line in- .cluding a line conductor and a release conductor, means for applying potential to said release conductor and for operating said line relay in a circuit over the line conductor of said line, contacts on said line relay for closing a self-locking circuit for itself to said release conductor and for opening its line circuit, and additional contacts on said line relay for closing an operating circuit for said lineswitch.

12. In combination, a line incoming to a lineswitch arranged to extend the line, said line comprising a line conductor and a release conductor, means for applying a potential to said release conductor and for closing a circuit over the line conductor for said any incoming trunk is taken for use, means line relay, and contacts on said line relay for closing a self-locking circuit over said re lease conductor, for opening its line circuit, and for closing an operating circuit for said lineswitch over the release conductor.

13. In a switching system, an automatic switch, a line incoming to said switch including a line conductor and a release trunk con ductor, means including a line relay in said switch for operating the switch immediately responsive to current flow over the incoming line conductor, and means for maintaining said automatic switch operated responsive to further current flow over the incoming release trunk conductor.

14. In a switching system, a preselecting lineswitch accessible to an automatic switch by way of a trunk line including a line conductor and a release trunk conductor, means for operating said automatic switch to extend a connection to the preselecting switch by way of said trunk line, means for operating the preselecting switch responsive to current flow over the line conductor of the trunk line incoming thereto, and means for maintaining said preselecting switch operated by means of current flow over the re lease trunk conductor of the incoming trunk line.

15. In a switching system, a non-numerical automatic switch, a trunk line incoming to said switch comprising a line conductor and a release trunk conductor, means for extend ing a connection to said switch by way of the said conductors of said trunk line and for setting up a current flow over the line conductor of the incoming trunk line and for applying a holding potential to the release trunk conductor oi the incoming trunk line, means in said non-numerical switch responsive onlyto current flow over both-said incoming conductors for operating the nonnumerical switch, and a circuit for holding said switch operated including the incoming release trunk conductor of said trunk line.

16. In a switching system, a plunger lineswitch having access to a plurality of lines, means for preselecting one of said lines, a trunk line incoming to said switchhaving a line conductor and a release conductor, means including an automatic switch forextending a connection to the lineswitch by way of said conductors, means for operating the lineswitch responsive to current flow over the line conductor incoming thereto, and a holding circuit for both of said switches completed over said release trunk conductor.

17. In a switching system, a plurality of non-numerical switches having access to trunk lines, a line incoming to each of said switches comprising a line conductor and a release conductor, a separate conductor multipling all of said release conductors together, a line relay in each of said switches, means for taking any one of said switches for use oyerithe incomin line. thereof; and for sett ng up; a; current; I

contacts on said line relay for'closing an op,- er'atmg circuit forthe switch andfor dis:

connecting the release conductor. otthe assov ciatedincoming line from thecommoncohductor;

l8: Ina switching system, a, plurality ottrnnlr lines accessible to an automatic switch,

each oiirsaidytrunk lines including a line conductor and aj release conductor, connec tions multiplmgall ofsaid release conductors:

together, a line relay -ineachof said trunk lines responsive to current flow overthe as-1 iow over the line con; 1 1 ductorot the incommgl ne, said line relay being respons ve to sald current flow, and;

s ciated line conductor when the trunk line l is taken for use by, said automatic switch,

and contactsjon saidline relay for, discone. necting the associated releaseconductor, from the common conductor,

19. In a, switching system, ,a plura-lity of automatic switches, a separate trunklineine coming to ea'ch switch, each trunk; line. in

cluding aline conductonanda release conductor, all; of said release conductors-being;

normally connectedtogether so that the: ap; plication of guardingpotential toone ofthem;

results in an application of guardingpotential to all or" them, means for taking anyone of said trunk lines for use, means responsive thereto for operating the switchin which the;

seizedline terminates and for disconnecting;

the associatedireleaseconductor from the other release conductors and for .closinga holdi.

mg circuit for the associated switch over the release conductor, meansfor subsequent ly opening the] holding circuit to permit the operated switch tov release, and means responsive thereto for applying a guarding potential to said release conductor.

20'. In a switching system, a plurality of automatic switches, a separate trunk line incoming to each switch, each trunk line ine eluding a line conductor and a release con erated switch to release, means responsive thereto for applying a guarding potential to said release conductor, and means for subsequentiy removing said guarding potential and for reconnecting said release conductor to the release conductors of the other trunk lines.

21. In a non-numerical switch having a line conductor and a release conductor incoming thereto, a line relay operative over the line conductor, and an operating circuit for said switch including said release conductor and closed responsive to the-energization of the line relay;

22. In combination, -a non-numerical switch, a line conductor and a release trunk conductor incoming thereto from a preceding automatic switch, and a magnet responsive to operate said non-numerical switch depending upon the closure of a line circuit over the incoming line and the application of a potential to said release-trunk conductor when the said preceding switch is operated.

23. In a telephone system, a line, an automatic switch and means for controlling the same to extend said line to an idle trunk line,

a preselecting secondary plunger lineswitch terminating said trunk line, means controlled over a talking conductor of said trunk line for operating said lineswitch when the trunk line is seized by said first switch, a release trunk conductor extending between said switches, means in said automatic switch for applying potential momentarily to said release trunk conductor and for removing it 7 after an interval, and means controlled through said secondary switch for applying potential to said releasetrunk conductor for maintaining the first switch in operated position after the potentialhas been removed from the said release trunk conductor at said automatic switch.

In witness whereof, I'hereunto subscribe my name this 13th day of June, A. D; 1928.

JOHN I. BELLAMY.

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