US1625235A - Automatic telephone system - Google Patents

Description

J. l. BELLAMY AUTOMATIC TELEPHONE SYSTEM April 19, 1927. 1,625,235

Original Filed July 8, 1921 2 sheets-sheet 1 Juhn IE Euamy April 19,1927. 1,625,235

J. l. BELLAMY AUTOMATIC TELEPHONE SYSTEM Original Filed July 8, 1921 2 Sheets-Sheet 2 nusn Dr Jhhn LB allsmg 4iwm Patented Apr. 19, 1927.

fiTATSES @FHQE.

JOHN I. BELLAMY, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

AUTOMATIC ELECTRIC (3F CHICAGO, ILLINOIS, A CORPORATION F DELA- WARE.

AUTOMATIC TELEPHONE SYSTEM.

Application filed July 8, 1921, Serial No. 483,117.

T 1e present invention relates to automatic telephone systems in general, but is concerned more particularly with such systems as include small community automatic exchanges which include party lines and which are connected with tl e main exchange by trunk lines, although some of the features are not confined thereto; and the principal object, broadly stated, is the production of new and improved circuit arrangements whereby the usual small group of incoming connectors in which the main exchange trunk lines terminate is entirely dis ensed with, and the said trunk lines are given access through the medium oi rotary trunk selecting switches to the local connectors which are used for setting up local connections within the C. A. X.

To explain the object somewhatmore fully, it is common practice, when an automatic connector switch is used by an operator in extending connection to a called subscriber, to arrange the said connector to reverse the incoming trunk conductors when the called subscriber answers, so as to give the calling operator answering supervision. However. it such a connector is used in a system of the type disclosed herein, when a subscriber calls another subscriber on the same line, the line relays of the connector switch are locked up in series with the windings of the back bridge relay when the incoming trunk conductors are reversed. in order to eliminate this difiiculty, it has been the usual practice heretofore to provide two groups of connectors. One group, termed inron'iing connectors, is used by the operator only and is arranged to give .so called reversed battery supervision when the called man answers. The connectors of the other group are used by the subscribers only and do not give reversed battery supervision. This arrangement, while obviously satisfactory from some standpoints, is very uneconomical in that each of the two groups of connectors, and especially the group of =t2oming connectors which is the smaller of the two, is very inefficient owing to the small number of switches therein. As pointed out before, the only diiliculty encountered when the connectors used by the subscribers reverse battery upon the answering of the called man, is when a subscriber calls another subscriber on the same line. Accordingly, a special object of the invention is to Renewed February 4, 1926.

provide means whereby a connector switch reverses battery in all cases when the called subscriber answers, except when the called subscriber is on the same line as that of the ailing subscriber, thus allowing the two small inelticient groups of connectors to be combined into one larger and more eflicicnt group.

Other objects notspecifically mentioned now will become apparent from a further perusal of the specification and will be pointed out in the appended claims.

Referring now to the drawings comprising Figs. 1 and 2 the apparatus shown on the left hand end of sheet 1 is located in a nanual exchange which is connected with a small automatic exchange by means of a group of two way trunk lines or which the trunk line comprising conductors 11 and 12 18 one.

T he remainder of the equipment shown on sheet 1, as well as the switching apparatus shown on sheet 2, is in the automatic exchange.

Referring now particularly to Fig. 1, the trunk line comprising conductors 11 and 12 terminates in the manual exchange in the jack J with which there is associated the visual supervisory signal 2 and the drop 3. The key K is a combination calling device and ringing key which, when thrown in one direction, inserts the common calling device S into the circuit, and when thrown in the other direction places the circuit in condition for ringing a called subscriber, as will be explained fully hereinafter.

Relay 5, associated with the jack J, in ad (lit-ion to the usual core, heel piece, and arn'iature, has a permanent magnet secured to the heel piece at one end and joined to the core atthe other end through the medium of a sot't iron yoke, as shown. This combination makes a very desirable polarized relay owing to its extremely simple principle of operation. With no current flowing thru the winding, the armature is not attracted owing to the fact that the connecting .yoke, core, and heel piece form a magnetic shunt around the permanent magnet. When a current flows in the winding of the relay in such a direction as to generate fiuxthat'is the same indirection as that which is normally shunted away from the armature, the armature is still not attracted owing to the fact that not only the core but also the permanent Ill magnet acts as a shunt, each When a current is sent through the windinc; in the opposite direction, however, the magnetic llux pa; through the permanent magnetand the core in parallel and returns through the heel piece and armature in so ries, thus causing the armature to be attracted.

'lhe trunk line comprising; conductors 11 and lil terminates in the automatic exchange in the line switch designated by the rotorence character U. This line switcln as well as the line switch U is of the well known rotary type in which the wipers have no no: d position and move in a :torward direction only and, in common with the other line shill-lies of the exchange, has access to a pluralib ot connector switches such as connector .ll.

ihe connector ll, which mechanically is of the vertical and rotary type and has its bani; contacts arranged in horirontal rows or levels is used by the operator in the manual exchange in exteudinc calls from whose lines terminate in the said manual etc, to subscribers whose lines terminate in the automatic exchange and, when seized by a subscribens line switch the line switch in which the sublino ctnpr' n conductors 1'73 and tern'iinates is us r extending a connrwtion to the nnuu'ial exchange or to other subscribers whose lines terminate in the same exchange, including other Sl1l)SClll1=Ol?F5 on the same line as that of the callingsubscriber.

'lhe substation i, which ln'idged across the line coinprisii conductors 172-5 and 175, is an automatic substation having the usual talking and signalling instrlnnentalities and also a calling device 55 "for controlling the automatic switches. In addition, there is provided a push button P, together with the resistance It. for the purpose of controlling the ringing relay in a connector switch after a number has been dialled. The resistance R, which is normally shunted by a pair of contacts in the callingdevice S, is inserted in the bridge across the line conductors whenever a number is beingdialled. lhe substation A, which is similar to the substation A, is equipped with a resistance R similar to the resistance E 0i substation A, with the exception that it is lower. The substation lir however, which is otherwise similar to the substations A and it, has no resistance corresponding to the resistances ll and R for the reason that it is bridged across the end of a long line equal in resistance to the longest line in the system.

The reason for adding the resistances ll and B to the substations A and A is to bring the resistance oi? each subscribei"s loop, while the impulses are being sent, up to one standard resistance, which is determined by the resistance of the longest line connected val scribor :lior the other.

in the system. By this means all the impulses delivered to the exchange switches are oi the same strength regardless of whether the substation from which they are s; sent is within a few blocks of the i ianc e or several miles away. The resistance it, associated with the operators calling device El, it may be stated, performs a similar tunction when the operator in the manual ei zchange is making an automatic call.

The system, having been described more or less in general, will now be described in connection with a detailed description of the operation ol the apparatus contained thcrein. l or this purpose it will bi assumed that the operator in the manual exchange is ex" tending a connection :t'rom a subscriber whine line terminates in the said exchange to the sidiscriber at substation i l, whose line terminates in the automatic exchange. In order to extend the said connection the operator inserts the other plug of the cord cir call in use into the jack tl, thereby operat ingthe tip spring of the said jack so as to disconnect the winding oi the drop 3, at the same time placing the spring *1; into engagementwith its working contact thereby clos ing the following bridge across the conduc tors 11 and iii: liron'i conductor l2, by way or the normally closed contacts controlled by spring El 0t key 1i, impedance ti, winding); of polarized relay 5, spring *1; and its workin contact, norn'ially closed contacts controlled by spring 7, and the normally closed contact controlled by spring S), to coi'iductor 'lhe conductors 11 and 12 are connected to ground and battery, respectively, in the automatic exchange in series with the line relay ill of the line switch C. .Jrccordingrly line relay ll ener ixes in response to the closure of the pre iously traced ljn'idge; and. upon so doing, closes, at armature 20, a cir cull; for switching relay ill) and stepping magnet in series; and, at armature l connects the test wiper 2:2 to a point between the winding; of relay ill) and the winding; of stepping magnet lirom this point the operation depends upon whether the trunlr line, upon which the wipers 2l-23, inclusive, are standing, ljiusy or idle. ll it is busy there is a ground potential on the re lease trunl: conductor thereot and consequently on test wiper i352; savitching' relay 3t) iort circuited; and stepping): magnet l which .interrn iits its own circuit, operates in l in manner ol. a humor to advance the switch wipers step by step in search cl? an idle trunk line. In the present case. however. we may assume that the trunk line, upon which the wipers or the line switch are siandii'igr, is idle when the call is initiated. That being the case, switching relav is not short circuitcd and stepping niairnct 15 i not operated because 0'! the high resistance of the said relay. Relay 30, however, energizes and at armature 17 places a ground potential on test Wiper so make the seized trunk busy in'nnediately, and at armatures 16 and 13 disconnects the line conductors l1 and 12 from the winding of line relay 14: and ground, respectively, and extends them by way of wipers 21 and 23, bank contacts 24 and 26, trunk conductors 2'7 and 29, normally closed contacts controlled by armatures 120 and 121, to battery and ground, respectively, by way of the Windings of line relays 104i and 102. Line relays 102 and 104 immediately energize over the bridge across conductors 11 and 12 in the manual exchange. Line relay 102, upon energizing, closes at armature 125 a circuit for release relay 103. Upon energizing, release relay 103 prepares a circuit for the vertical magnet at armature 127 and at armature 128 grounds the release trunk conductor 28 by way of the resting contact or" armature 143 and said armature. By means or" this ground potential on test contact and its multiples in the banks of the other line switches, the connector H is maintained busy in the usual manner. This ground potential extends also by Way of test wiper 22 and armature 17 and its working contacts to switching relay 30 thus establishing a holding circuit for said relay before the slow actlng line relay 1 1 has had time to deenergize. A branch of this holding circuit extends by way of private normal conductor 13 to mul tiple test contacts in the banks of the connector switches, thereby guarding the calling trunk line against intrusion in the usual manner.

Returning now to the polarized relay 5, the winding of which is included in the bridge across conductors 11. and 12, the said relay is energized at this time owing to the fact that the flux generated in the core is parallel in direction to that emanating from the associated permanent magnet and con sequently a magnetic circuit is set up through the said magnet and core in parallel and the heel piece and armature in series resulting in the attraction or the armature. The said armature, upon being attracted, places the visual supervisory signal 2 in multiple with the lower trunk conductor and the line relay 102 of the connector H. whereupon the said supervisory signal becomes energized The operator may now throw her key K to calling position, whereupon springs 7 and 8, upon being operated, remove the polarized relay 5 and impedance 6 from the bridge across conductors 11 and 12 and insert the common calling device S, together with its resistance R, therein. Polarized relay 5 and the visual signal 2 now become deenergized. As has been mentioned before, the resistance of R is just high enough to bring the resistance of the calling trunk line up to the resistance of the longest line included in the system.

The operator may now manipulate her calling device in accordance with the first digit of the desired number, thereby interrupting the circuit of line relay 102 of connector H a corresponding number times. Each time the said line relay 102 deenergizes in response to these interruptions it closes at armature 125 the following circuit: From ground by Way ofarmature 125 and its resting contact, armature 127 and its Working contact, resting contact of oil normal spring 116 and said spring, slow acting series relay 107, and vertical magnet 112 to battery. By the operation of the vertical magnet, the shaft and Wipers of the connector H are raised step by step until the latter come to rest opposite the level of contacts in which the line of substation A terminates. The slow acting series relay 107 is maintained energized throughout the series of interruptions and at armature 138 serves to maintain the circuit of the vertical magnet intact after the off normal springs have shifted, as they do upon the iirst vertical step. As a further result of the ener ization of relay 107, it places the resistance R in multiple with line relay 10 1-, at armature 137. This is done so as to afford a better impulsing circuit for line relay 102. At the end of the series of interruptions, slow acting relay 107 deenergizes and at armature 137 moves the resistance R from in multiple with line relay 10%, and shifts the iinpulsing circuit from the vertical to the rotary magnet at armature 138.

The operator may now manipulate her calling device in accordance with the second and last digit of the desired number, where upon line relay 102 is deenergized a corresponding number of times and. upon each deenergization, completes the followi' cir cuit: From ground by way usly of aprevi traced circuit to armature 138, and thence by way of the resting contact of the said armature, slow actin series relay 103, resting contact of armat "e 133 and said armature, resting contact of armature 1&9 and said armature, and the resting contact oi. armature and said armature, to battery by way of rotary magnet 113. By the operation of the rotary magnet, the switch shaft and the wipers 161464;. inclusive, are rotated step by step until they finally come to rest upon the desired set of contacts, which in this case the contacts 1054.68, inclusive. being the ones in which the line of substation A terminates. Slow acting series relay 108 is maintained energiz d through out the series or interruptions and at armature 139 holds the circuit of stepping relay 110 open, and at armature 1 10 maintains the circuit of relay 111 open and closes a circuit --Q= :i new,

in N39, upon for slow acting rclaj lllll. lle

in lrom energizing, disconnects lest \ri arr the upper winding ol' hsich l/l'l l re relay loo :1 armature ill and connects it due o l-- per winding of su'iuhiiu; relay and at armature Mil places the ii" in multiple with lhe wind he relay lll so as to allord a better i h on; circuit lor line relay EH13. M the end oi. the .wrie oi? iuterraplions slow acting); relay llirl l'alh; hack; wanna-ts up the lest rrla if ill) at :llllhllure 11:35 ciwee :1. point in the circuit oi Hix'llilllllrlg, relay ill at lire normally cloreil lfohiizu'iz roui'rolled iiy arinalure ill): cou illlflfi the upper winding); of the dieri'iininan mg relay Hill in series with lhe release lrunl: coiuluclur ii -l at armature ill); and it, lhe normally open contacts controlled i the said arihaliur opens llll circuit of re i itauri i '1 arm: rarer; attracted for an inlerral i Ill 1 :1 now he aired l'rnn rrouiuhl ll ol' armature lie of relrane relay lull, liilll 1 \rorhi rout-act, upper \iiu o; uniting relay loll, rel; a lru c 13%, and thence in war of a prei'iom y iraceu circui" to hatt h way or eu'iti one reiaj. 130 o i line an ll. lliscrneinair reel 10%), upon era: mg, closes a lochiug circuit or m an arinzituie I and c i rcui rere re. 11 g; rel a3 lit Lure 13o.

lhe more operations take place invariel) when a eul uion l5, called th: 1%; on a lll other than llnit oi. the callii aliscrilier. or operate: :15 the 1: i n :13 V ljroin um point, however, 'rurtucr operation depen .1: upon Whether the cal ed line is or. or idle. Assuming new that t u: line ol eh i iil'ion .IL i5 ousy there a guarding 'oiiud potential on test contact in? and consequently no current ilo'ws through the upper Winding; oil :u'iitching rehry ill for the reason that; both ends o t the said \i'indi are cennc "ted to ground and consequently, the said rel-a doc not energize. Slow actiiw relay, 10h upon deenergizing, removes re slance ll; from in multiple with line relay llll at arn1nlure ll-EZ, short circuits the upper winding of rela loll at armature i l-3, and at arrow.- Lure lll disconnects the test wiper 163 from the upper winding ell switching relay ll. and connects it to the upper winding: of he combined liusy and heel; bridge relay 105, by way of the res 'ing contact of armature l3; and said arn'ia'ture. Belay 105, ergiziu; closes the il'ollou'ino; h M cult for itself at arn'ieture L3 3 he its initial circuit hrohen at armature H ll 1* rom ground by '21:; 03'? the working contact elf armature 126 and (l armature, lower said arnmture, resting contact of armature lizlfi Hi3 and Sail", armature, and rotary magnet .llil to battery. l'lehry i053 in; maintained encrsriz-ied over lhii; circuit but the rotary ict ll is not ener ized on account of ":h rer-dulauce ol ll, and the lower windinn; 0! relay um. rile a lurtluir result ol? the euergiizalion o i lay 105, it connects; a lead 'i'ronl the busy signalling machine to the upper heavy talking conductor by Way of a(.'n'ial:ure 1:122 and its working contact,

and the renting; contact olf armature M6 and eaid zirunilure. lly Luis operation, the Lfillilllflf operator )5 given an audible busy l signal to HILULUI her than the called line It:

to i contact 167, Pli'tlle normal conductor ll-l, and the switching relay and stepping 'n-iigisnet oi" the line switch G, to battery. igirritc relay 111 ol the connector H and itching rela i oil the line switch are the 5*. energized in series over the above traced eireuit hut the steppiiu; magnet of the line :rwiich l, is not energized on account of the hin h resistance of the associated switching j- '-3ill 'l he switching; rela ol line switch C, upon energ zing, disconnects the conductors 1723 and 1 5 from battery and ground, respectively, hut owing to a mechanical interlocking device (not shown) between the armature of the said switching relay and that oi the line relay ol the said line switch, the armature oi the Raid switching relay is ope'ated only about; hall we and conse q iently the wipers of the line switch are not connected up at this time.

In the connector H, switching relay 111, upon energizing, closes a locking circuit for l. at armature lll in series with the rotary magnet 11 Without, however, operuh ing; the said magnet on account of the high resistance of the lower Winding; of switching; relay 111. its a further result oi the operation or the said switchingrelay 111 it connects up the line wipers 161 and 16% at ern'ia'tures lle and 150; disconnects the test wiper '2, at armature MT; and at armature lle places direct round on test wiper no, at the some time disconnecting its own upper winding from the raid test Wiper. Blow acting rel-a 105) now deenergizee with the llQl'BllllJCEOl'U mentioned results.

The operator, having finished c; llinp; the desired number, now throws her key K to the oppoeite or ringing position, thereby operating the springs 9 and 10. Spring 10, upon being operated, disconnects the visual signal 2, while spring .9, upon being operated, inserts the resistance E into the bridge across conductors 11 and 12. In the connector H, line relay 102, being adjusted relatively stiflj', falls back in response to the placing of the resistance E into the brid across conductors 11 and 12 but line relay 104, being adjusted relatively light, is maintained energized. Upon deenergizing, line relay 102 completes the following circuit: From ground, by way of armature 125 and its resting contact, armature 127 and its working contact, normally open contacts controlled by 06? normal spring 116, armature 138 and its resting contact, relay 108, armature 129 and its working contact, armature 117 and its resting contact, ringing relay 101, resting contact of armature 145 and said armature, and rotary magnet 113 to battery. Neither relay 103 nor magnet 113 are energized over the above traced circuit, but ringing relay 101 is energized and at armature 123 maintains the release relay 103 energized, while at armatures 122 and 124 it disconnects the wipers 161 and 164 from the upper and lower windings of back bridge relay 105 and connects them to a source of ringing current, as shown. As long as ringing relay 101 is energized ringing current is sent over the established connection, thereby operating all the bells on the called line.

When the operator restores her key K to normal position line relay 102 is energized. Upon energizing, line relay 102 opens the circuit of ringing relay 101 and closes the initial circuit of release relay 103 at armature 125. Upon deenergizing, relay 101 removes the multiple ground from the circuit of release relay 103st armature 123 and at armatures 122 and 124 disconnects the called line from the source of ringing current and connects up back bridge relay 105 again. The operator may repeat this process until the code of the called substation has been sent out, it being understood of course that each substation is signalled by sending out a different combination of rings. lVith the key K in normal position, the visual supervisory signal which falls back each time the key K is thrown to ringing position, is operated over its previously traced circuit.

When the called subscriber responds by removing his receiver, a direct current bridge is closed across the conductors of the called line, whereupon back bridge relay 105 energizes and at armature 134 completes the following circuit: From ground by way of reversing relay 100, armature 134 and its working contact, working contact of armature 136 of discriminating relay 106, and said arnlature, working contact of armature 149 and said armature, resting contactof armature 145 and said armature, and rotary magnet 113 to lmttery. Rotary magnet 113 is not energized at this time owing to the high resistance of reversing 100 but the latter relay is energized and slur the control circuit of the ringing relay 101 from the said relay to release relay 103 at armature 117', so that in case the ringing key is operated, either by intent or accident, after the called subscriber has answered, the ringing relay is not operated and the release relay is held up over the ringing relay control circuit. as a further result of the operation of reversing relay 100 it reverses the trunk conductors 27 and 29 at armatures 120 and 121 rela as regards their connection with the line re-.

lays 102 and 104 thus causing a reversal of the direction of current flow in the bridge across conductors 11 and 1.2 in the manual exchange. Polarized relay 5 now retracts its armature owing to the fact that the major path of the magnetic flux extends through. the electro magnet and the permanent magnet in series and consequently does not include the armature and heel piece, the said arn'iature being kept from completely touching the iron yoke by the usual brass residual screw (not shown). Upon falling back, the armature of relay 5 opens the cir cuit oi the supervisory signal 2 which deenergizes to give the calling operator answering supervision.

Assuming that the jack J isconnected with the jack in which the calling line terminates, as has been mentioned before, by means of a cord circuit or by any other suitablemeans, the two subscribers may now converse with each other, the talking circuits that are shown being outlined by heavy conductors,

Vhen the conversation is finished the two subscribers replace their receivers. Then the receiver is replaced at substation A the circuit of back bridge relay 105 is opened and the said relay, upon deenergizing, opens the circuit of reversing relay 100 at armature 134. Upon deenergizing, reversing relay 100 reverses the trunk conductors 27 and 29 back to normal, whereupon polarized relay 5 attracts its armature, thereby closing a circuit for the visual supervisory signal 2 which operates to give the operator a disconnect signal.

In order to release the connection to substation A, the operator removes the plug from the jack J, thereby connecting up the drop 3 to the tip spring of the jack, at the same time opening the bridge across conductors 11 and 12 at spring 4. The current through the winding of polarized relay 5 now ceases and the magnetic flux emanating from the permanent magnet takes its normal path through the soft iron core, whereupon the armature, which as mentioned hereinbetore is provided with the usual so called resiilual screw, 'lalls hack, thereby opening; the eircuit of supervisory aignal l which heronicf ileuerpgizetl.

lu theeonnerror l-l line relays .ll'l'l El'lUl 102 (lemma-ghee in responee to the opening: ol? the la". acrosa coutluctora ll and lil. liiue relay 10?, upon (lenergiaiug, opens the cir euil o releat'ie relay 103 at armature lilo. lleleai e relay 1.025, upon (lenerginiau. removes the gllfillllll potential from release trnnlr con- (lat-tor Q8 and private normal conductor l'i'el, and open the looking circuit oil? IOlll tl 108 and ill at armature 128, whereupon the said relays cleenergize. As a further result oi? the leenereyieation oi? release relay 103, a circuit is; cloretl by way of armature 1255 and its resting contact. and oil norinal contacts 115, tor the release mag-net lll. rly the operation ot the release mag-net, the shaft ancl wipers of the connector H are restoretl to normal poeitioln the circuit of the saiil release magnet being opened at o'll' normal. cortacta no h the shatt when it reaches normal position. The switching r lays of the callinn and CllllOtl line switches olniouel (leenerchange now releztsetl.

ll e shall assume now that the suhi-eoriher at euhstation A desires to *all the sutuseriher at substation [V which is another substation on the same line.

llhen the receiver is removed at substation A, a circuit is eloeerl over line conductors lit-l and 175 for the line rela r' of line switch C and the eaitl line switoh C operates in the same manner as the line switch C hi l in the previous call to give access to an idle trunk line leading; to a connector switch. We shall assume. in this case also. that the connector ll is the first one found to he ii'lle ancl is consequently the one seized.

'lhe calling suhscriher now manipulates his eallin lGVlCQ in accordance with. the digits ol the elesiretl number whereupon the connerlor ll. operates in exactly the same manner as it (ll(l in the previous call until the wipers: Mll 131i. inclusive, are hrongrht into eugaheiuent with the contacts .lllii-"l.lll-h ineluszire, ol. the callecl line.

It .may he pointeil out that while the call.- illgl ilevice 51 of the euhstation A is of? non mal, and conaequentl v while it is interrupting; the circuit of line relay l0? o'lf eonneetor ll. the resi tance ll is inelutletl in the hriiln'e across ("OlKlllC'i'OlS l and lit) an (l hrinais the reaiatauce ot the calling; line. up to the resietanee oi the lougreatline connect-ail in the system.

lVe shall now lahe up the operation of the connector H at the point where it (litters from its operation in the preceding: call. at the earl of the rotary movement, slow acting relay 108 (leenergizes with the hereinhetore (lOSClllKKl. results, of which one is the inserting' of the upper whirling; of discriminating relay 1am in series with the release trunk mnnluetor QR. lliscrin'iinatiunrelay 106, heineg nia e'inally atl iusterl, not energized in lllllease. lunrerer, owing to the tact that it is i-lllllll'((l hy the upper winding); oli switchinn; relay I ll which in at this time connected in series with the switching relay ot the line switch C. which is not only the line switch oil? the ealleil line hut also the line switch ot the calling: line. Switching; relay 111, however. owing to the variation of the potential. of the release trunl: conductor 23 caused by the inserting of the upper winding of relay 106 therein. is able to operate sulliciently to cause armature M8 to make contact with its working: contact, thereby closing its previously (leseriherl looking circuit which causes the saicl rela '1 ll. to pull all the way up with the hereinhetore ileserihetl rosull'a. As one result of the operation ol switching); relay ll 1, direct ground is plaeecl on the test wiper H53 at armature 13118. ohviously short eirouitino the upper winding: of discriminating relay 106 complet ly. as soon as the line wipers lli'l anrl ltel are eonneeterl up at armatures 1.4-6 and 1.50. of switching; relay 111i hack hritleje rela; 105 energizes over the ffl lffl line. which in this case is the calling line. in eeries with the hrirla e across COUClHO- tors 1.73 and 175 at auhstation A. lt will he noted that the upper anrl lower windings of the saicl rela are in multiple with line relay ill-l a. (l line relay 102. respectively, and that, it may he statetl. is the principal reason for arrane'ine the connector l-l. so as not to rererae hattery when a call. such as the one now leinn" tlescrihecl, is made.

The suhsc iher at suh tation A mav now operate the push hutton P a numher of times corresponil i to the numher of rings necesearr to s' jnal the suhaeriher at substation l-"i. whereupon line relay 102 o connector ll rleeneruizecl a corre ponding numher oli' tirees anrl upon each rleenergization eanses rineino current to he sent out as: here inhe'lore tleserihetl. therehy ringing; the hells at su stat ons 1V anrl JV.

When the suhseriher at suhstation A hears hie ootle heina' set out; he reaponrls hv reinoviurr his receiver. therehy placing: a see- Olli'l rlireet cu rent hrirlege acroe conductors l7? and l? whereupon the Further operin tion oi the rinoinp; pueh hutton hecomes olwiouslv inetlectire to cause ringing" current to he sent out. lhe calling; and eallerl suhserihers mar now eonroree with each otheix tallrinp; cu rent heine' sunnlietl to the transmit-ten: througrh the lVlllillllfl'S o l haeli hriilge relar I05 anil also through the Whirlinns of line relays 10 laml I02,

l l hen th ronxe aation ie finie zwl the two subscribers replace their receivers whereill) upon the established connection is released in the manner hereinbetore described.

We shall now assume that the subscriber at substation A desires to call subscriber whose line terminates in the manual exchange.

When the receiver is removed at substation A the line switch operates in the. usual manner to extend the calling line to an idle connector switch and, assuming that the connector H is the one to which the connection is extended, the line and release relays energize iii the usual manner thus preparing the switch for operation.

The calling subscriber now operates his calling device in accordance with the digits of the desired number, thereby causing the connector H to bring its wipers 161-164, in elusive, into connection with the contacts 169-17 2, inclusive, to which the normal conductors 11, 12 and 13 of the trunk line comprising conductors 11 and 12 are connected.

The sending of impulses from the substation A is accomplished in the same manner as the sending of impulses from either the substation A or the substation A with the exception that no resistanceis introduced into the bridge across conductors 173 and 175 when the calling device S is moved from its normal position. Owing to the fact that the line resistance is equal to the resistance oi the longest line in the system,

any added resistance is unnecessary.

Since there are a plurality of trunk lines, such as the trunk line comprising conductors 11 and 12, any one of which suliice to extend a connection to the manual exchange, the connector H is adapted to automatically rotate in search oi an idle one of these trunk lines it the first one of the group happens to be busy. The trunk line comprising conductors 11 and 12 is assumed to be the first one in the group and consequently the two test contacts 170 and 171 are jumpered together. The same is true for the test con tacts of the succeeding trunk lines, with the exception that those of the last trunk line in the group are not connected together.

Returning new to the operation of the connector H, it will be taken up at a point where it differs from that already eX- plained. At the end of the rotary movement slow acting relay 108 falls back fol lowed by the energization of the discriminating relay 106 which energizes in series with the switching relay of the calling line switch in a manner hereinbefore described. From this. point the operation depends upon whether the. trunk line comprising conductors 11 and 13 is busy or idl.. Assuming that it is busy, there is a ground potential on test contact 170 and stepping. relay 110 energizes immediately after armature 139 falls back, over the following circuit. From ground by way of test contact 170, test contact ot' the armature of rotary magnet 113 and the said armature, and stepping relay 110 to battery. Upon energizing, stepping relay 110 closes a circuit for slow act'- relay 109 at armature 144 before the s: d relay has tallen back, and at armature 145 closes the Following circuit for rotary i'i'iagnet 113: From ground by way of armature 12S and its working contact, normally closed contacts controlled by armature 140, working contact of armature 145 and the said arn'iature, and rotary magnet 113 to battery. Upon energizin rotary magnet 113 advances the wipers 161464, inclusive, into engagement with the contacts of the next trunk line, at the same time opening the circuit of stepping relay 110; upon decncrgizing, stepping relay 110 opens the circuit of slow acting relay 109 at armature 144, and at armature 14.5 opens the circuit of rotary magnet 113 which deenergizes and closes a pointin the circuit of stepping re lay 110. This process is repeated over and over as long as the wipers of the connector engage contacts of a busy trunk line, but it all the trunk lines of the group are busy. when the last one is reached, or the one that does not have a jumper between its test contacts, there is no circuit closed for the step ping relay and consequently the rotary movement ceases. lVith this condition existing slow acting relay 109 finally falls back, and at armature 141 disconnects the test wiper 163 from the winding of switching relay 111 and connects it to the upper winding of the combined back bridge and busy relay 105 with the final result that a busy signal is sent back to the calling subscriber in the same manner as has been described hereinbefore, when the operator was calling.

In the present case however, we shall assume that the trunk line terminating in bank contacts 169172, inclusive, is idle when the call is made as described. Such be the case, when the wipers 161-164, inch...ive, of the connector H arrive on the set of contacts of the said idle trunk line, there is no operative circuit closed for the steppirelay 110 (the resistance of the upper winding of switching relay 111 being high enough to prevent the said stepping relay 110 troni energizing in series with it) and switching relay 111 energizes in the usual manner; opens the circuit of the ro tary magnet 113 and closes a locking circuit for itsel; at armature 149; opens the circuit of stepping relay 110 at armature 147 grounds the test wiper 163 at armature 14o. and at armature 146 and 150 connects up the line wipers 161 and 164.

In response to the placing of ground on lit) icst wiper use, switching relay 30 of line switch t." is cncrgiucd over private normal his push button 2nouiciuurily. thereby causing); the conzwcior ll to seal ruining: current out ()\'(l the established connection to operate the drop 3. When the operator in the manual ctcchau 'c by inserting: a plug}; in the jack ill the drop 3 is cut oil and bed nr d 'o is placed across res line are 1x versed at the bun ol' connector fl thus sending; 11 ci'u'rout through the said ulariaed relay in :1 direction opposite to i 1 in which it must llow to operate the 'ihe cal subscriber and the operator now convcr: with each other in the usual manner and the ope ator may er;- tcnil the connection to the desired subscriber in any well known or approved way.

.ii'lter the conversation iinishcd the subscriber at substation A replaces his receiver, whereupon the connector ll restores itself to normal position in the usual lnani'ier. As soon as i the around potential is removed -from the private normal conductor 12 switching relay 30 ot the line switch C deenergjr us and again connects up line relay 14: which energizes over the bridge across coiuluctors l1 and in the manual exchange and is operated in the usual manner to picl: out an idle trunh line. whereupon the i'iolarized relay 5 is energized and closes a circuit for the visual supervisory signal 2 which becomes operated to a" "'c the operator a disconnect si nal.

ll hen the operator removes the plug; from the jack J? supervisory signal 2, polarized relay a, line switch U. and the connector to which the connection has been extended, assume normal. position in the usual manner.

llarino described and ascertained the tealures of the invention, what is considered to be new and desired to be protected by the l icttcrs Patent will be pointed out in the appended claims.

lVhat I claim as my intention is:

1. ln an automatic telephone system including party lines, a connector switch for connecting: a calling and :1 called line, means in said connector for reversing; the direction at current i low in the calling line, and means tor preventing such reversal in case the calling: and called lines are the same.

2. in an automatic telephone system including; party lines, a connector switch tor connecting calling and called lines, means in said connector for reversing; the direction of current flow in the calling line when the subscriber on the called line answers, and means for preventing such reversal in case the calling and called subscribers are both on the same line.

3. In an automatic telephone system in cluding party lines, a connector switch controlled 'lroin a calling station to extend a connection to :1 called station, means in said connector tor reversing the talking battery supply connections of said calling station when the subscriber at the said called station answers, and means for preventing such reversal in case the said called station is on the same party line with the said calling station.

%l. In an automatic telephone system including party lines, an automatic connector switch for connecting calling and called lines, a reversing relay in said connector iulapted to reverse the direction of current flow in any calling line connected to such connector, circuit connections for energizing said relay in case the calling and called stations are not on the same line, and other citcuitconnections for preventing the energization of said relay in case the calling and called stations are on the same line.

ln an automatic telephone system ineluding); party lines, an automatic connector switch tor connecting calling and called lines. a reversing relay in said connector adapted to reverse the direction of current How in any calling line connected to such connector, circuit connections for energizing said relay in case the calling and called stations are not on the same line, a discriin inating relay for rendering said circuit connections e'llectivc. and circuit arrangements tor preventing the energization of said discriminating: relay in case the calling and called stations are on the same line.

(5. In a telephone system, main and branch exchanges, party lines in the branch exchange terminating in individual line switches, trunk lines extending from the main exchange to the branch exchange and also terminating in individual line switches, connector switches in the branch exchange accessible to all said line switches in common, said connectors being controllable either by an operator in the main exchange or by calling subscribers in the branch exchange to connect with branch exchange lines, suitable circuit arrangements in said connectors whereby any calling party line subscriber in the branch exchange can call another party on the same line, and reversing relays in said connectors for reversing the direction of current flow in the said trunk lines when the connectors are used in main to branch exchange connections in order to give supervision to the main exchange operator.

7. In an automatic telephone system, subscribers lines, automatic switches for c0nnecting said lines. calling devices at the stations on said lines tor controlling said switches, resistances at the said stations nor mally excluded from the line circuits, and a switching device controlled. by each calling device when the san'ic is operated. t'or inserting the ass'ciated resistance in the line cir cuit. V

S; In an automatic telephone system, sub scribers lines. automatic switches for con nccting said lines, calling devices at the sta tions on said lines for controlling said switches, a resistance at each of said stations, each resistance having a value such that when added to the resistance of the associated line the total line resistance will approximate the line resistance of the longest line in the system, said resistances being normally out of circuit, and a switching device controlled by each calling device for inserting the associated resistance in the line circuit when the calling device is operated.

9. Inan automatic telephone system including party lines, a connector switch for connecting a calling and a called line, means in said connector for reversing the current flow in the calling line, and means for preventing the operation of said reversing means in case the calling and called lines are the same.

10. In a telephone system including party lines, an automatic connector switch controllable over a calling party line to complete a connection to the calling line or to another line, a signal controlling device at the calling station, signalling equipment in said connector controllable by said device. to signal the desired station. means in said connector controlled through the direct current talking bridge at the called station for rendering said signalling equipment unresponsive to said device, and means for rendering the operation of the last named means ineffective when the called station is on the calling line.

11. In an automatic telephone system, a party line, other lines, an automatic switch controlled from a calling station on said party line for connecting said party line with any one of said other lines, and an artitical resistance at each of certain ones of the stations of said party line, each of said resistances being of a value such that when it is added to the resistance of the portion of line between the associated station and the exchange the total resistance approximates a definite value determined by the length of the longest line of the system.

12. In an automatic telephone system including party lines, a connector switch for connecting a calling and a called line, and means in said connector switch for reversing the current flow in the calling line only in case the calling line is not also the called line.

13. In an automatiotelephone system including party lines, a connector switch for connecting a calling and a called line, a reversing relay in said connector switch for reversing the current flow in the :alling line, and circuit arrangements for operating said reversing relay to make such reversal only in care the calling line is not also the called line.

It. In an automatic telephone system, lines, certain of said lines being party lines, a connector switch for connecting a calling and a called one of said. lines, a relay in said switch for reversing the current flow in a calling line, and a discriminating relay in said switch for preventing the operation of said reversing relay ii the calling and the called parties are on the same line.

15. In an automatic telephone system, party lines, other lines, switches for establishing connections between said lines, each station on said lines equipped with a calling device for controlling said switches, a resistance at each of certain ones of the stations on said lines for changing the resistance of the associated line to approximate the resistance of the longest line in the system, said resistances being normally out oi":

circuit, and means for inserting the asso ciated resistance in the line circuit only during the operation of the calling device.

16. In a party-line telephone system, a connector switch responsive to a control over a calling line to complete a connection to a called line. and responsive to control from said called line when the latter is a calling line for completing a connection to said called line, the control exercised over said connector being the same in both cases. a relay included in said connector, and means for operating said relay incidental to only one of said connections.

17. In a party-line telephone system, a connector switch responsive to a control over a calling line to complete a connection 1 to a called line. and responsive to control from said called line when the latter is a calling line for completing a connection to said called line, the control exercised over said connector being the same in both cases, and means included in said connector for discriminating between said connections.

18. In a party-line telephone system, a connector switch controlled over any calling line to set up a connection to another called line and to set up a connection to the said calling line as a called line, and means automatically operated by said connector to discriminate between said connections, said connector being subjected to the same ex ternal control in each case.

19. In a party-line telephone system, a connector switch controlled over any calling line to set up a connection to another called line and to set up a connection to the said calling); line on :1 called line, a supervisory control device inclnded in said connector and operated incidental to only one of said connections. and a supervisory device ontaide ot raid connector and under the control ol said anperrinory controlling device.

220. ln a narty linc telephone system. a (.onnector switch controlled over any calling line to set up a connection to another called line and to set up a connection to the said calling; line as :2 called line, a anperrisory controlling; relay in said connector auton'iatically operated iini'idental to only one of said connections. and a supervisory device ontaide o't eaid connector and under the control of mid supervisory relay.

2-1. In a party line telephone system, a connector switcln a pair of talking conductors and a release trunk conductor incoming to said switch, ineana :[or controlling said switch over an calling; line and orer one oi said incoming talking conductors to set up a connection to another called line and to set up a connect-ion to the said calling; line as :1 called line and means automatically operated by said connector over said release trunk conductor to discriminate between said connections.

22. In a party line telephone system, a connector switch, a pair of talking conducmamas tors and a releaao trunk eonl'lnctor ll'lCOlTling to said switch talking: wipers and a test wiper for said switch. means for con trolling said connector awitch over any calling line and orcr one ot eaid incoming !alking conductors to set up a connection to another called line and to set up a connection to Faid calling: line as a called line. said (OINHCl'lOHH including: said incoming condnctora and said wipera. and means auto matically :qqerated liy eaid connector and controlled jointly over the incoming release trnnk conductor and said lest wiper to diacriininate hetwecn eaid. connections.

In a party line tclei vhone syslenn a connector switch controlled over any calling line to set up a connection to another called line and to set up a connection to said calling line as a called line. a discriminatiinr relay in said connector means for operating" said relay when the connector completes a connection to a line other than the calling line and circuit connections for preventing the operation of said discriminating relay when the connector completes a connection to the calling line.

In witness whereof, I hereunto subscribe my name this 30th day of Jane, A. D. 1921.

JOHN I. BELLAIXIY.

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