US1128469A - Automatic telephone-exchange. - Google Patents

Description

G. W. LORIMBR. AUTOMATIC TELEPHONE EXCHANGE.

APPLIOATION LB Y 31' m Patent-,ed Feb. 16, 1915.

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UNITED sTA'rEs PATENT oEFi'cE.

GEoRGE W. LomMEn, or PIQUA, onio, Assionon, BY passim AssmimEN'rsQD y WESTERN ELECTRIC COMPANY,

A CORPORATION F ILLINOIS.

AUTOMATIC TELEPHONEEXCHANGE.

for its object to enable calls made by a substation equipment in an automatic exchange to be held in abeyance for future completion, if the necessary connecting devices for such completion are first found engaged,

and to accomplish this result without de` rangement of connecting devices or loss of tra/flic. Its further object is to regulate the control of the unitary groups of connecting devices without wasteful operations on the part of the controlling devices.

My invention is of a character to operate in harmony with and as a part of the system of automatic telephone exchanges which Ihave invented jointly with James Hoyt Lorinier, and which is disclosed in Letters Patent of Great Britain granted to us in 1901, and numbered 8648 of that year. In this System-the lines of the exchange ai'e divided into groups, each group comprising a convenient or desired number ofy lines, say for example 100. Our earlier invention permits switching apparatus to be' provided in a relatively small plurality of connecting units, each like another.` For example, for 100 lines'tliere may be provided from three to seven unitary connecting outfits. These are practically duplicates of one another and are adapted alike to be used by -any one' of the substations of a group of lines for effecting connection with the line of another. substation -in that or vanother group. Each of these. sets of apparatus for connecting purposes is termed a division,

r and in practice as many divisions are to be employed as may be necessary to switch the calling lines at the time of the greatest trnllic which is considered at the time the extent of the installation is determined. .In -connection with a plurality of divisions installed for switching a group of lines, is installed one set of devices for the group, and these have to do with the control of various operations performed `by the divisions. One of these devices common to a plurality Specification of Letters Intent.

appucauonliiied my 31,1906. semi-m. 819,416.

ratenteanenie, 1915.

lof divisions, eine decimal indienen@- .other is the division starter or division .se-

lector and another is'the vdec'zimal register cont-roller. 'particular that my presentinventionisaddressed, although itis as well related l-to other devices which coperate withithe division starter in its functions. i

My invention is illustrated lin the aecompanying drawings in which similar letters referto similaiparts, and in which:

Figure 1 shows the decimalindicatons another rotary switchFig. 3 shows thefdivision starter and Fg. 4 details of thedivision starter clutch.

It is to the division starter' in relays and one :rotary switch; Fig. 2 shows .f

The three sheets of. drawings comprising l these figures are capable of beinglviewed as one drawing by causing the lines 3. angdj'of Fig. 1 to register with those'lines ofvFigsy 5e and lines 2f) and 26 of Fig."1 to register' with those lines of Fig. 2. When' so'joined,

Figs. 1, 2. and 3 become a single drawing through which the various circuits may be traced.

The decimal indicator shown in-I1`ig.-1I is a.

combination ofi several commutatore and collecting rings, having variouseircuits permanently connected to the segments ofthe commutators or to the collecting ringsv themselves. In the form here considered, the decimal indicator has four commutator rings and tivo collecting rings, upon eachof which one brush moves. The brushes are adapted to revolve each in the circumference friction clutch connecting it with a main power; shaft. This carrier is further adapted tothe capable of arrest when required,

andthe brushes, when the carrier is so ar- I rested, will stand, while the driving shaft continues to rotate in the friction clutch.

.lVhe'n/ the arrest is interruptedthe brush .ciated with a third, the latter being* for guarding purposes,to prevent a busy from'being calledY lOnlyone of-the'ltiil wiresvof the line 1s lcarriedto the decimal I of its own ring, w-hile the rings themselves are stationary, and the carrier which bears all the brushes is constantly drivenrby-a indicator, "such-wiresvone.. each ctl00 insulated segment. The act of instituting a call from a substation is to connect one wire of the line with the earth or common return wire, this conductor, whether earth or wire, having connection at the central olice with one of the terminals of the central oilice battery orvequivalent. In this specification the terminal so grounded is taken as the negative one. The wire grounded at the substation in institutingr the call is in this specification designated as L'; the wire so marked in Fig. 1 will be engaged by the brush 37 lwhen the decimal indicator is in the position shown in that drawin When such Contact is made, current Wil flow from the positive pole of the battery, through the collector ring 38, by brush 39, wire 40, relay 27, back Contact of relay 28, wire 41, brush 3T, Wire L', to the substation, and by ground to the negative pole of the central oilice battory. Relay 27 closing will operate the clutch magnet 30, causing the pawl 42 to engage the circular rack 43. As the pawl 42 is carried with other relays and magnets with the brushes of the decimal indicator, and as the rack 43 is stationar with the commutatore and rings, all t e brushes will be arrested so long 'as the rack 43 is engaged. The circuit by which the magnet 30 is energized is as follows: positive battery terminal, wire 40, magnet 30, contacts of relay 27, wire brush 45, ring 46, wire 25, pair of brushes 24 or 24, either or both, perhaps in parallel with others equivalently related, then b wire'26 and relay 33 to the negative terminal of the battery. ln addition to operating the clutch to stop the decimal indicator, the relay 33 is operated. But it will be observed that neither the clutch magnet 30 nor the relay 33 could have received current but .for the path 'between the wire 26 and the wire 25 beingl closed by la" `brush 24, 24, or some other similarly related connection.' These brushes, such as 24, are in the rotary switches, of which one is shown in Fig. 1, and another in Fig, 2, And the relation of such switches to other devices is that there is one of them in each division of connecting apparatus, and that they assist in setting up the connection by changing functions and relations among the devices as their brushes step from one position to another. These rotary switches, as Well as the division startershown in. Fig. 3, are conveniently made in `acylindrical form, being composed of contact pieces set in insulating material, and adapted to be engaged, where exposed on the Inner surface of the insulating cylinder, by brushes attached to an. axis at the center of the cylinder. Permitting the cylinder. to remain ixed, Wires can be attached to the various Contact pieceson the outside, leaving their inner endsl free to be en aged by the brushes as described, In t ese drawings masses the cylinder switches are all three shown as developed surfaces, and the same is true of the commutatore and rings of the decimal indicator. Likewise I have shown the cortactpieces in. the form of circles, for clearness 1n the drawings, whereas they may loe in this form, or may be flat conducting pieces adapted to be engaged by fiat brushes in the common manner,

The position of lthe brushes 24 and 24 in the ligures is a normal one, and one in which they would rest iii the division owning the rotary switch were not in use setting upa connection or permitting a conversation; but ii it is doing either, the brushes 24 and 24afwil1 be insome other than normal position, and exceptin the very berotary switches of a given group of divisions exactly' as they are to the two which l' show, Thus, for eachdecimal indicator there are a number of divisions; for each division there is one rotary switch; in each. rotary switch there is a. tap from the wire 25, and one from the wire 26; if any one rotary switch Aassociated witha given decimal indicator (a given section is in normal position, the wires 25 and 26 will be connected togetherd It none is in normal position these wires will not be connected together, while if more than. one is in normal position the condition will be the same as that of one only being in normal position. Recalling that the relay 33 operated siniult'arieously with the clutch magnet 30 in the act which stopped the decimal indicator in rotation, it may now be seen that at the relay 33 the negative terminal of the battery is connected at the contact to the wire 3. In the division starter (Eig. 3) it Will be seen` that the brush connecting with the wired is also connected to the wire 3 iti-whatever position that cylinder switch may stand, The circuit then continues from wire 4 to 5, thence to wire fl, unless the brush of the wire 5 be out of Contact with one of the terminais of the wire 6; this will extend circuit through one winding of the magnet 19 to the positive terminal of the battery, so energizlng the magnet 19. But this magnet is that of a clutch adapted to startand stop the rotatable brushes of the division starter shown in Fi 3, and as a result of being en ergized by e described connections, the division starter will be caused to rotate through an angle, for the following reasons and with the 'Following results: The magnet 19 opcrates the pawi'Q'i, shown in Fig. 4, and this is adapted to engage notches in the periin eter of the disk 20. This perimeter is shown developed in the lower part of F ig. 3,' and it should be observed that the notches bear a relation to the vertical rows of Contact pieces in the upper part of Fig. 3. The perimeter of the disk 2O has twenty notches in two sets of ten each. 1f the pawl 21 be in any normal notch, as indicated in Fig. 4, the brush of the wire 5 will rest upon a contact connected with the wire 6. But if the pawl be out of a notch, or in any other than a normal notch, connection between wires 5 and will he broken. The disk 20 is related to a constantly rotating shaft in a relation somewhat similar to that described concerning the decimal indicator. The relation. is

vthat the shaft continually rotates while the disk 20 is only geared to it when the pawl 21 is drawn out of a notch. The described operation of the vclutch 19 draws the pawl 21 out of the notch in which it rests,this being a normal or N noteh,-in each .Successive beginning of operation of the division starter. Assuming. the 'leftnhand N notch et 2O in Fig. `3, the pair o fA brushes 7 will be caused to move two steps, producing `Contact fourth row of contacts, coiinting downward,

between the positive batteryterminal of the and the wire 8 of the third rowgr thence through the pair of `brushes 9. off thertirst f rotary switch, and the clutch magnet'lfto normal position the negative batteryterminal. Theclutch 3l is #similar to that fof'. other selector switches, and upon operation causes`the brushes to begin rotation within thatrotary switch. vThe reason for clutch 31 operating instead of the clutch 32, or thatof stillv some other rotaryswitchoisi that the wire 8, rather than the w1re18 or 18, etc., was engaged by this step of the division starten If, ho'wfA ever, the wire 8 were one representing a rotary switch already' engaged by another connection, the

criminated, and would vhave sought' and found a non-busy rotary switch aswillybe described later.. lt is to be noted'that on,l

the division starter brushes moving-from' the N position of 20, 5 isfbroken. from 6,A so

denergizing, the connectedcoil of the clutch ,place immediately uponfthe movement of thedivisionstarter;

19, and' ith'at this. took Butas shown in Figf; theY pawl 21 when' out of a vnotch in 20,-cannot` stop thatydisk until it vpresents division starterwill turn until pawl-j21^-falls in the next S,- or sub-normal notch; and

similarly there occurs a movement from that notch vto vthe next normal notch, becausef'ff the following-reasons; The construction'fof I the rotary-'switch is such that upon the 'ogeration of .its clutclil, it moves from t e ofFig. 1, so as to bring the brushes into the fourth vertical row to the right?v of the shown normal position.y At

this point '23a or 23 will engage wires` 11 division starter would havedisf starterL relay 33 another notch,l so thiitthev magnetl would have been open. Als, in- 120 and se or 11s and 22a This will connect the wire`11 onli withxthe negative terminalgof the battery, so energizing all foutofthe suc# cessive Icontacts in the division starter, which are connected to the Wire'll, and'by the wire 12, .whose brush rests on these points, will extend this circuit to the relays 34 and 35 respectively. Through the conductor.13 and its brush, this circuit then extends from the relays mentioned to the positive` terminal of' the battery, in all positions of the division starter except when the pawl 2l is in anN notchof the disk 20. .In 'any S position, therefore, the relays willjbe energized with the described conditions. f Any operationof the relay .34 is immaterial' in this connection, but-1 the operatioiiof the relay vi'will connect wires 15 and.16,"wit h the result that the clutchimagnet19 'will .be energized over the path from negative?."hath tery 15, 16, .17,1I magnetll), tofthe positive battery terminal. Pawl `21willy be vdrawn outoif the S notch in 20, and the 'g^'ea,rir1'g-ozA 20 Etoy the? constantly' rotating shatwill move therbiushes b'orn'e vby 2 0' forward' untilg.; i. the breaking-off contact. btween thebrus `ofthe wired andithe positiveterminal of the' battery, thefelutch magnetxlQ' is d enerl gized;V Because of this, thepawl 21 engalges 2D", .Tbut` thisr time in 1 an N notch; ready 1to1' a successivecompleteycle: AIt -is tohe'nbted I that' theengwgement, 1n therbtryswitch,

can only exist when a rotary switch is out of its normal position, and will be maintained after once established', untilv the rotary switch .returns to `itsnormal position. If in 110 receiving its .originalil impulse,l theV 'division d set the divis'onstarter inxnotion' from the 'normal position selected in .this descript'iim, 'aiidni the brushes of conductor 9`fhad been' out of engagement 115 withiconductors @and libecause-that rotary switch'viiee` out of iiormal position,- there would have been no seizing of thaty rotary: Switch,A because the circuit of the clutch stead .of the brush of. 12 finding no potential on the. last contact ofthe'wire r11, 1t would have,i found .negative potential, preventing, through the aetion'of the relay 35, a stoppage fof the dvisionfstarter in the S posi tion. If the contacts'of 111, 11", etc., correspondin to successive rotary switches, had been ound of negative vpotential by the brush'nf 12, it would mean 'that the rotary switch of those groups of lcontacts' were in 130 use, that is, outI of normal position. Therefore in engaging each such group, the relay 35 would be caused to continue the division starter in motion, and it would not stop on an S position until it had en aged an idle .rotary switch, operated its c utch, and moved its brushes far enough from normal position to denergize the clutch 19, leaving the division starter finally in one of its normal positions. Of these, it will be recalled, there are ten.

ln the absence of special precautions to the contrary, an operation of the division starter relay 33 would set the division starter in motion in Search of an idle rotary switch and if there were no rotary switch so idle, and in normal position, the division starter would repeat its cycles of search indefinitely, until a rotary switch, having passed out of use, might receive an impulse through its clutch magnet, and in response furnish potential over its conductor 11, 11,etc. This useless and continuous search is obviated by the extension of con ductors 25 and 26 through an entire section with taps to the various rotary switches. It will be observed that the conductor 26 so taps in parallel to the various rotary switches, and ends by passing through the winding of the relay 33 to the negative terminal of the battery. The lconductor 25, in a. somewhat similar manner, is tapped into the rotary switches in arallel, but terminates in the ring 46, having a circuit finally ending in the positive battery terminal. As previously described then, current may reach the relay 33 under certain conditions, but never when all rotary switches are oil' their normal position. The division starter,l therefore, may not begin a search for P. row tary switch unless the existing fact is that some rotary switch of' that section is idle and is waiting to be selected.

The main control circuit from positive battery terminal through 38, 39, 40, 30 and Q9 in parallel, contact of 27, 44, 45, 46, 25, 26, 33 to negative battery is adapted to start the main starting switch only when'one or more subsidiary switches are in normal position, thereby providing one or more bridges 24, 24a between wires 25 and 26. This circuit constitutes at the same time a. main control circuit for the main starting switch, and a stop circuit for the decin indicator. The storting circuit or control circuit for each subsidiary switch extends from negative battery terminal through 31, 9, 8 and is under control of brush T in the main starting switch, and also is inoperatiwv when brush 9 is not in normal position. A. secondary control circuit or guard circuit exists for cach subsidiary switch` extending from negative battery terminal through 22, 23, 11.,l 12, v 34 and 35, `13, ,le to positive terminal of battery, this circuit being closed in the subsidiary switch only when such switch is olf normal. The starting circuit extending through 19, l6, 5, 4, 3, 33, is con.-

trolled directly by contact of relay whose helix is included in the .main starting circuit, or stop circuit lor4 the line-seeking brush. c f

The relay 29 is a relay whose function is the placing of a busy test upon the line detected by the division indicator during the period between the stopping of the indicator upon the line and the taking of the line by an answering device ory ivision. The wire G is the guard wire or busy-test wire of the line L', and by the contact of relay 29 this wire is connected during the period mentioned through 4O-'-3 9-38 to the positive terminal of the battery. The relay 29 is in parallel with the clutch magnet 3() and is energized only during the period when that clutch magnet is energized. The operation of the relay 29 therefore is dependent upon the continuity oit the circuit through wires Z5-9.6. The object of the relay 29 therefore is to prevent the calling line from being talren by some distant automatic selecting and connecting dei/ici` which, under control of another subscriber through a distant answering device may be seeking the line herein assumed to be calling through the decimal register of Fig. 1.

Having thus described my invention, what claim as new and desire to secure by Letters Patent is:

l. In an automatic. telephone exchange, a main starting switch, one o1' more associated switches each adapted to be moved from normal position in response to current under control of said main startin switch, a circuit for said starting switch Xtending to cach of said associated switches. and means in said circuit adapting said main starting Switch to move onlyv when one or more o1"V said associated switches is in normal position.

2. n an automatic telephone exchange, u main starting switch. one or more subsidiary switches, acontrol circuit for said main starting switch adapted to start the same only when one or more of such subsidiary switches is in normal position. a starting circuit for each said subsidiary switch under control of said main'sturting switch and means rendering said starting: circuit inoperative when its associated switch is not in normal position- 3. ln un automatic telephone exchange, :i main (Tntrol circuit, u starting switch controlled A..thereby, one or more `subsidimy switches under control oi said starting switch, :i control circuit for euch subsidiary switch open when the sulisirliarjfY switch is not in normnl'position. und over which its .subsidiary switch muy be controlled. and a secondary control circuit lending from osu-h Y switch.

ofV said subsidiary switches to said' starting switch and closed when such subsidiary switch is in predetermined positions awayv from normal, and controlling said starting switch.

4. `In an automatic telephone, a malin control circuit, and a Arelay therefor, a startingswitch controlled thereby, one or more subsidiary switches under control of said startin switch, a control circuit foreach sub si iary switch, 'open'when its switch ,is not in normal position', and a'secondar'y control circuitfleadingfrom each said subsidiary switch and closed when such switch has movedefrom normalposition, said secondary circuit controlling in 'part said starting 5. In van automatic -telephone exchange, a main starting switch an controlled said main sta'iltng switch, and

a current supply circuit for `said control relay, open when all saidsubsidiary switches 4. ,y i are out of normal position. '2% (5L-Inailv automatic telephone exchange having lines in groups'i a starting switch, one or more subsidiary witches and a con.-

A trol relay for each/group; [a clutch magnet ,v for each subsidiary switch, operable -over 3B a control circuit ,from said y s tarti switch except .wliensaidfsujbsidiary yswitch'is out of lnormal"I p sil'. i,` o'n3"l a .glmrd circuit for" each subsidiary switch, open when the subsidiary switch is in normal posi'tiomand contactsv in 3i; said starting',switch,'.pneor` more for each .guard circuit.v` I, v u Y ,7 an auto l ftic .telephone .exchange 'giving lines in groups, a starting switch for each group, one ormore subsidiaryswitches .lo yfor eachI group, ai control relay for said starting switch, a .control oircuitthercfor, "open when lall thesubsidi'ary switches of a group are out of normal" position, a second control relayfor said startin switch and a .33S clutch magnefoperable there y.

8. In anautomatic-telephone exchange, a unitary group of .switches comprising a startinv switch rand subsidiary switches and .,i; controlbcircuits for each; each of said sub- S) sidia-ry switches being controlled .initially only through said starting switchg. successive series ofrcontacts in said starting switch, one for each control circuit of said subsidiary switches and a brush ada ted to 575 vengage .them one at a time; means a apting .plione *el changes', a` clutch magnet having i twofwi'n" ,ings-,the saidlwindings having like operative effect on the clutch 'and each in a .l A,a control relay therefor,` one or more-sinsidiary switches circuit normally open, means closing one circuitonly when a'call is instituted by a subscriber, and means closing the other circuit only thereafter.

10. In a starting switch for automatic telephone exchanges, fixed contacts and movable brushes therefor, a clutch-magnet having two windings, the said windings having like operative effect onA the clutch erable only when one or more rotary switches are in lnormal position.

12. In an automatic telephone exchange, a starting switch, a line-seeking brush, a line commutator and a stopping clutch therefor, one or `more rotary switches, a stop circuit for said line-seeking brush operable only when one or more" rotary switches are in normal position, and a start- `ing circuit for said starting switch operable only when said stop circuit is energized.

13. In an automatic telephone exchange, a normally moving line-seeking brush, aline commutatoiga normally idle starting switch, subsidiary switches, a stop for said line brush, starting .means for said stai-ting switch, and means simultaneously energizing said stop and said starting means, said u last means being operable only when one or more subsidiary switches are in .normal pol sition.

14. In an automatic telephone exchange, a normally moving line-seeking brush, a line commutator, a normally idle starting switch, subsidiary switches, a stop for said line brush, starting means for said starting switch, and means simultaneously energizing said lstop and said starting means when 'a call instituted by a line, said last means being operable only when one or more subsidiary switches are in normal position.

15. Iir. an automatic telephone exchange, a normally moving line-seeking brush, a line c mmutator, a normally idle starting switchi subsidiary switches, a lstop for said line brush, starting meansv for Said starting switch, and means simultaneously cnergizing said stop and'said starting means only when a subsidiary switch is in normal position.

16. Inn an automatic telephone exchange, a normally moving line-seeking brush, aline commutator, a normally idle starting switch, subsidiary switches, a stop for said l,inebrush, starting means for said starting Switch', and means simultaneously energizing said stop andsaid starting means only when a call is instituted by a line while a subsidiary switch 'is in normal position.

17. In an automatic telephone exchange, a division starter, a decimal indicator clutch-magnet, one or more rotary switches, a control relay for said division starter and a control circuit including said clutch magnet, said control relay and parallel contacts in all'said rotary switches.

18. In anautomatic telephoneexchange, a stop magnet, a starting relay, cordinate rotary switches and a circuit closer in each, and a control circuit serially including the stop magnet, the starting relay and one or more oS-aid circuit closers in parallel if two or more are included.

19. In an automatic exchange, a rotary switch, a starting circuit normally closed in said switch, a guard circuit normally open, a control circuit normally closed included therein, and means openin said starting and control circuits when sald guard circuit is closed. c. Y

20. In an automatic telephone exchange, a starting switch; a line-seeking brush; a

line commutator for said brush; a sto pingir clutch for said brush; a plurality or subsidiary switches; and a stop circuit for said line-seeking brush, said stop circuit passing through normall closed contacts of 'said subsidiary switc les, said contacts being open when said subsidiary switches are ofl' scf normal and said contacts being in multiple with each other,said stop circuit thus being closed through said switches when one switch is in its normal position, substantially as described.

21. `In an automatic telephone exchange, a starting switch; a line-seeking brush; a line commutator for said brush; a sto ping clutch for said brush; a plurality o subsidiary switches; and a stop circuit for said y line-seeking brush, said stop circuit passing through normally closed contacts of a plurality of said subsidiary switches, said con- ,tacts being lo en when said subsidiary switches are o normal and said contacts being in multi le with cach other, said stop circuit thus eing closed through said switches when one switch is in itsnormal position, substahtially as described.

22. In an atomatic'telephone exchange, a starting switch; a line-seeking brush; a line commutator for said brush; a stopping clutch for said brush; a plurality of connective units having off-normal'switches; and a stop circuit for said line commutator and passing through the off-normal switches of said connective units and lclosed when any f.

connectivedevicel is in normal position, substantially as described.

23. In au automatic telephone exchange, e starting switch; a Ene-seeking lbrush; .a

@munter fof .sad bruhsa .stepping and a starting circuit for said starting 'v switch operable only when said stop circuit is operated, substantially as described.

24. In an automatic telephone exchanve, a starting switch; a line-seekingbrush; a line commutator for said brush; a sto. ping clutch for said brush; a plurality o subsidiary switches; a stop circuit for said line-seeking brush, said stop circuit passing through normall closed contacts of a plurality of said su sidiary switches, said contacts being open when said subsidiary switches are off normal and said* contacts being in multi le with each other, said stop circuit thus eing closed through said switches when one switch is in its normal position; and a starting circuit for said starting switch operable only when said stop circuit is operated, substantially as de,- scribed.

25. In a telephone exchange system, a normally moving line-seeking brush; a line commentator; a normally idle starting switch;` subsidiary switches; a stop device for said line-seeking brush; a start-ing means for said starting switch; and ar circuit'controlling said stop dcviceand deswitch operable only when said stop circuit is operated, substantially as described.

27. In a telephone exchange system, a group `of lines; a call-seeking device pertaining to sai-d lines; connective devices for' answering calls upon said lines; means whereby said call-seeking device may indicate a calling line when a connective device is available for use; and means .rendering said call-seeking device inoperative to indicate a call when a connective device is not available, substantially as described.

l 28. In a telephone exchange system, a. group of lines; a call-seeking device pertaining to said lines; connective devices for answering calls upon said. lines; means whereby said call-seeking device may indicate a call and designate the calling line when a connective device is available for use; and means rendering said call-seeking device inoperative when a connective device is not available, substantially as described.v

29. In a. telephone exchange system, a

oup of lines; a call-seeking device pertaining to said lines; connective devices for answering calls upon said lines 5 a connectivedevice starter; means whereby said callseeking device may indicate a calling line when aconnective deviceis available for use; and means rendering said call-seeking device andi said connective-device starter inoperative when a connective device is' not available, snbstantially as described.

30. In a. telephone exchange system, a group of lines; a call-seeking device pertaining to said lines; connective devices for answering calls upon said lines; a connectivedevice starter; means whereby said callseeking device may indicate a calling line when a connectivedevice is availabe for use; and means rendering said connectivedevice starter inoperative when a connective device is not available, substantially as de'- scribed.

31. In a telephone exchange system, a group of lines; a call-seeking device; connective devices; a connective-device selector; and means for rendering said connectivedevice selector inert when all connective devices are busy, substantially as described.

32. In a telephone exchange system, a group of lines; a call-seeking device; connective devices; a connective-device starter; and means for rendering said call-seeking device inoperative when all of said connective devices are in positions other than their normal position of waiting, substantially as described.

33. In a telephone exchange system, a group of lines; a call-seeking device; connective devices; a connective-device selector; and means for maintaining said connectivedevice selector inert when all connective devices ,are in positions other than their normal position of waiting, substantially as described.

In a telephone exchange system, a group of lines; connective devices for said lines; a connective-device starter; a call seeking device; means whereby a. calling line may act through said call-seeking device to control said connective-device starter; Asaid means acting through oinorinal switches of all of said connective devices and being inoperative when all of said ofi'- normafl. sivtchcs are out of their normal positions, substantially as described.

taining to said'lines, connective devices for answering cal'lsupon said lines, a starting device for said connective devices, said starting and said connective devices being each adapted to control the starting of the other.

37. In a starting switch for automatic telephone exchanges, lvfixed contacts and movable brushes therefor, a clutch magnet having two similarfwindings, means for momentarily including one winding in aclosed circuit when a subscriber institutes a call, and means for thereafter including the other winding in a. closed circuit.

38. In a telephone system, the combina,-

tion with a telephone line, of a plurality of switches for association with said line, a common relay and a circuit for its winding having branches extending to a plurality of said switches, andimeans controlled bv said relay for starting an idle one of said switches when a call is initiated on said line.

39. In an automatic telephone system, one

or more connecting switches, a. starting'l switch associated with. said connectin switches, a circuit therefor, branches of sai circuit controlled by the connecting switches to prevent the operation of the starting switch if all of said connecting switches are out of norma] position, and means controlled by the starting switch to start said connecting switches.

40. In a telephone system includibg a telephone line, a line relay, a plurality of similar'switches, a common starting device for said switches and a circuit therefor controlled by said relay, saidcirouit havin branches extending to a plurality of sai switches.

Signed by me at Piqua, county of Miami, State of Ohio, in the presence of two witnesses. GEORGE W. LORIMER.

Witnesses:

GEORGE A. V'ANomR, WILBER C. RolsoN.

lois

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