US938541A - Telephone-exchange system. - Google Patents

Description

I G. L. ZAHM.

TELEPHONE EXCHANGE SYSTEM.

APPLIOATION FILED SEPT. 19, 1905.

Patented Nov. 2, 1909.

3 SHEETS-BHEET 1.

Witumoeo U. L. ZAHM. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. 19, 1905.

Patented Nov. 2, 1909.

3 BHEETB-SHEET 2.

3mm C01,

G. L, ZAHM.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED SEPT.19, 1905.

938,541 v Patented Nov.2, 1909.

' 3 SHEETS-SHEET 3.

Witnesses 3 i l Application filed September 19., 1905: Serial No. 279,123.

- unirnnsrarps rarnnr OFFICE.

oHAnLiis L. zAHM; or'Los ANGELES, CALIFORNIA, Assrenoa or ONE-FOURTH 'ro- EDWARD n CLEMENT, or WASHINGTON, msrnrc'r or COLUMBIA.

TELEPHONE-EXCHANGE SYSTEM.

To all whom'vlt-may concern:

Beit known that 1,.CI1ABLES 'L; ZAHM, a citizen, of the United States,

State. of California,-have inventednew and useful Improvements change Systems, of which the following'is a specification.

My invention relates to telephone ex.-v change systems, and has for itsiobject to produce means whereby subscribers working on an automatic system may trunk directly into the manual system, without making any substantial change in either the automatic or ,manual .equipment, but retaining allthe advantagesof both. v

According .to one arrangement I cause a subscriber who comes in on a first selector of the well known-'Strowger type, to select an idle second selector switch through which connection maybe had directly to a manual switchboard through axtrunk'line, or, if-

desired, any of the ordinary connector switches maybe reached and through any of them the call may also bemade to a sub scriber who may also have manual switch board -conne'ctions., With this arrangement it must be obvious that I obtain a verygreat degree of flexibility in my system. possible through the second selector to get onto a toll board,

the tool or other manual My invention is illustrated in the accompanying drawings, wherein,

Figure 1 shows indlagram a subscribers' station, a standard lfirst selector-switch. of

Strowger type, and a second selector switch of thesame type-wherein I have made cer-. tainchanges so as to be-able totrunk. d1-

rectly to a manual switchboard. Fig. 2 is a similar diagram showing-fatr11nk'. ack, -on. the manual sw tchboard. with the connectlve I -cord clrcuit and also a scribers' station with its linel terminating on a manual switchboard Fig. 3;is a simi.-

lar. diagram showing a Strowger connector switch wlth certain changes,- which allow Specification of Letters Patent.

residing at Los Angeles,-.1n the county of Los Angeles'and in Telephone Exinformation. apparatus, etc.. with expedition and certainty; while The first selector switch Z -lar Strow'ger type without change, need not common battery sub Patented Nov, 2, 1909.

,V Whose line terminates in a Referring now to vFig. 'l, the subscribers I station A isequipped with apparatus usually v found in local battery systems, consisting of the transmitter T, receiver R, hook H, and

. ringerQ. In addition to the foregoingtalk ing set there is added the sending apparatus .for' transmitting impulses to operate the switches at central. I have .for I represented the sending apparatus by the two push buttons K, K. when depressed grounds number. 1 side of the line, and sendsimpulseswhich operate vertical relays in the various switches, while the button K when depressed ,sendsin an impulse over number 2 side of the line which operates the rotary'relays. At the end of the conversation, both buttons are depressed sending in an impulse-over both sides of the line simultaneously, afiecting both the verti- Simplicity 1' The button K cal and rotary relaysand releasing the varivousjswitches. Button K, when depressed,

after sending in the last set of impulses, o crates the ringing relay in the connector switch.

V The switches I employ at thecentral oflice are preferably of the 'Strowger type.

shown in Letters Patent Nos 815,176 and 815,321 to Keith and Erickson, dated March 113, 1906, although Ido not limit myself thereto, reserving the right to employ others Where desired, with the necessary non-essential" changesin circuit-s and connections.

being the rogu be described in detail. The vertical relay S responds. to impulses over one side of the -line,.and operates the vertical magnet E whose armature 0 controls a pawl which engages a ratchet on thespindle z causing it to step up in a vertical position. This spindle carries the'trunk w per-s12, 2 andthe The rotary. relay S responds to which causes themechanically voperated side ,switches s, 2 stand ,2 to turn one point, cutting-on. the rotary ma 'net D w hfi turn movesthe side swltclies another oint connecting the line wires to the trunk Wipers.

The'release relay X is connected to the test wiper a 'and' controls the circuit of the release magnet W which, when operated, restores the switch to its normal position.

In the second selector switch Z wherein part of my invention lies, I have inserted additional apparatus and wiring which enables me to signal and be connected to a manual exchange without the necessity of using the ordinary connector switch. I will point out the additions and changes as I proceed with the description. The vertical relay S which responds to impulses over the vertical side of the line, operates the magnet E which steps up the spindle .2 vertically, in the same manner as described for switch Z. The rotary relay S which responds to impulses over the rotary side of the line, operates the relay A, which I have inserted. One tcrminal of this-relay is connected directly to battery, while the other terminal is connected to the ring of a trunk jack on a manual.

switch-board. The trunk wires 25 and 26 are continued through to the tip and sleeve springs of the same jack. I have also added the two normally. closed contact springs .12 and :0 to the release relay B1, so that in stead of the spring 8 of the relay S being connected directly to the spring f of the re lay F it is connected indirectly through these two additional contacts. In addition to theforegoing, I have added the three contact springs 2 2 and 2 which are 0perated mechanically by the spindle a To the contact 2 I have connected the terminal of the release relay X which leads to the private wiper 2. The normally open con tact a is connected to one terminal of the lamp L on the manual switchboard Fig. 2. I have connected the firstcontact in the sideswitch a to battery through the contacts of the relay A, the reason for whichwill becxplained later. l

Referring now to Fig. 2, I- have shown the manual switchboard end of the trunk which consists of the lamp L and jack J having the tip spring 7', sleeve spring 7', and ring f.-

The cord circuit which forms the connecting link between the second selector switch and the subscriber whose station is equipped with plug P by the following path: 101, condenser C 103, contacts 0?, 0*, 105, to 7). The ring p ,of the plug is connected to ground by the wire 113. The relays K and K are connected to the tip and sleeve respectively, of the plug P,'and are connected permanently to battery at their middle pomts,

while the other terminals are connected to normally open contacts. Both of these relays are of the locking type, and each one controls the circuit of the lamp L. The relay K after becoming locked, is released manually by the operator throwing forward her listening key which opens the circuit of the relay. The-relays K, K are connected to the tip and sleeve of the calling plug P ,w respectively, one terminal of the relay K being connected to grounded battery, and one terminal of the relay K being connected to the free side of batte thus supplying current for talking to the called subscriber; These two relays jointl control the circuit of the lamp L e relay K cannot become locked unless the'calling plug P'is inserted in the jack of 9. called line which energizes the relay K, closin the locking circuit of the relay K, so it'fo ows that after this rela becomes locked it cannot be released unti the calling plug is withdrawn from the jack, denergizing the relay K The subscribers station A is equipped with apparatus usual in common battery systems, which consists of the trans mitter T, receiver R, hook H, ringer Q, and

condenser C; The wires from t is station terminate ina central office on a line relay M throu h the normally closed contacts of the cut-oil relay N. This relay when energized upon the insei ion of the plug P, attracts its armatures, disconnects the line rela and connects the line wires to the springs 3 7''- cf the jack J'.

Referring now to 3 I have shown a connector switch Z wherein I have added apparatus and wiring which in connection with the equipment already described in Fig. 2 enables me to call automatically 8. subscriber in a common battery exchange. I V

will point out as we go along the additionsand changes I have made. The vertical reside of the line, operates the vertical magnet E causing the spindle z to step up vertically The rotary relayS" responds to imsecond point in the switch z".- This second v lay S responds to impulses over the vertical ave point in the Strowger system is connected to a normally open contact in the private relay F and the contact which engages it is conrelay connected to the ing connected to the free side of the battery.

Battery being thus bridged between the two windings supplies talkmg'current to the subscrib'er 1n the manual system, and also fur-- nishes means for pulling up the cut-off relay,

- therelay S";

I connects disconnecting the line signal, and providing a busy test as will be explained later.

In the Strowger system, the arm of the side-switch e is connected directly to the private wiper 2", but between these two points I have-insertedthe release relay 'X having the contact an grounded, and the .contact a connected to one terminal of therelease magnet and to the contact 8 of It will be seen that instead of having-the magnet IV act as the test as in the Strowger system, local circuit of the relay X to, or becomes energized, by 015 current such as would be a small amount received in test ing a busy line in a manual system." The test in such cases is generally produced by the difference in potential between two relays or coils. spon'd to'such currents" as it is simply built and requires a certain amount of currentvto operate. I have not changed the circuits of the ringing relay Y in the slightest, which when becoming energized opens the calling end of the trunk and generator current to the calling end.- I'have connected the test contacts 2 which in the Strowger system are normally free from any connection, to the tip contacts of the lines in the manual exchange which are in parallel with the multiple and jacks of the manual switchboard. Thetip and sleeve. contacts in the switch are coin nected in parallel with the tip and sleeve springs respectively in the same answeringand multiple jacks.

In the operation of thatpart of my system where a connection in a common battery manual exchange where the conditions are such that he cannotcallthe subscriber automatically,the procedure is as follows: He is first connected, to a second selector switch and from there Strowger system have respectively, the other I have placed it in the which responds The magnet W will notre-' answeringcalling subscriber wishes for a' operator completes the connection through her cordcircuit tothe wanted subscriber.-

The calling subscriber first depresses the button K sending impulses, the numberof which will" correspond .to the exchange Wanted. The impulsescoming in over number I side of the line operate the relay S,whi ch at tracting its armature closes the circuit of the magnet E- by the 'following path: ground, 36, s,-s,v 34, f, f, 31, E, 35, t obattery B, The operation of this magnet causes the spindle 2 carrying the trunk-wipers a, 2 and the test wipers and come-oppositearow of contacts'leadlng to a groupof second selector switches of my to step up vertically; I

changed typeewhi'ch have 'accessdirectly to,

a manual switchboard;

over number=2 side of the" line, operating, the relays, which in turn closes of the private relay Fby the follo ing path;

ground, 36, s, 8. 37, F, 38, to battery B This relay operating opens the contacts f, disconnecting the verticalmagnetE andpre-,

yentingthe spindle z from making'a Verticalmovement, F also causes the to move one oint, and in the switch -The 'subs'criber now depresses a buttonfK, sendinganqimpulse;

'85.v the circuit;

The operation of the relay side-switches a, 2 z, 27,

at, clos 3 ing the circuit of the rotary magnet D. The

circuit of this magnetbeing'closed causes its armature to vlbrate, which in turn rotates the spindle 2 until the Wiper a finds a con tactiu the row not busy, that is'to say, free from grounds. As soon as such'a contact is foulhd the relay F becomes deenergized and causes the side switches to take the third I position cutting off the rotary magnet I and causing the spindle to come to reist with' the wipers on contacts leading to, an idle second selector. switch; fgized while the switch is rotating and the wiper ,2? is passing over -tacts by the following path: 5, 44,37, F, 38, 35 tobattery X does not become energized on account of its winding being and in series of The side switches in wires 1, 2 to the wires the grounded-con- B.- The 'relay' of a verylow resistance;

.the winding of the relay F .which is of comparatively high resistance. f

10 5'. The relay F is keptener-,

3 and 4 respectively leading to the Wipers 2? I I and eiand ground the test contact .2 \following path: ground, 65, toe. The calling subscriber is now con nected to a second selector I leads directly to a manual switchboard; Instead ofsending inadditional set of impulses'he now'simply depresses the buttonKj "which in the ringing button. sends. an impulse ov'er operating the vertical the circuit of the vertical magnet-E by the following path: ground, 8}, s 49, mt,

switch which ye ,,X, 435 5 i v v 2 Strowger system would be'the I [The pushing of this button No.1 side of. the line relay S which closes f, f, 47,1 3, 45 to battery B. The energiz- 1 mg of this magnet causes the spindle e to step up vertically to thefirst row of contacts, closing the contacts z and 2 which 5 completes the circuit of the line lamp on the switchboard b the following pathzxbattery B, 45, 61 a, a, a .62, 50, 2 57, X, 58, 59,. 2 2 2 27', lamp'L to ground. The re lease of the difierent switches is effected by 10 :the release'magnet first becoming energized and then deenergized thus constituting a two-step escapement. As the back release relay X is in series with the lamp L it becomes energized and, attracting its armature,

16 closes the circuit of the release magnet W 53; the following path: ground, m :0 54, 60, to battery B. This magnet becoming energized takes the first step toward releasingthe switch'Z. The contacts m and w 20 of the magnet X are broken, disconnecting the vertical magnet "E, thus preventing the spindle z -from taking a second step in case t e subscriber should depress the button K the second time. The calling subscriber has 2 5 now signaled and is connected to the manual switchboard over No. 1 side of the line by the following path: 1, 2 3, e, 5, j of the jack J and over No. 2 side of the line by the following path: 2, z, 4, e 6, 26, to j of the jack J.

Referring now to 2, the operator at the manual exchange erceiving the lamp L glowing inserts the p 11g]? into the jack J throws forward her listening key 0 in the ordinary manner, and asks for the number wanted, The insertion of this plug Hoses the circuit of the cut-off relay A in the sec-U ond selector switch Z log the following path: ground, 113, p ,j ,-28, 6,4, to battery B.

4 This relay becoming energized attracts its 1 armature opening the contacts a, a, a disconnecting the vertical and rotary relays S and q and opening the'circuit of the back release relay X whose armature now as sumes its normal position and opens the circuit of the release ma et W restoring the switch Z to its norma position. The spindle in returning'to its normal position "opens the contacts 2 and e extinguishing thewsignal lamp L,

Referring a ain to'Fig. 2, the operator upon finding t e number wanted inserts the calling plug P into the jackJ of the desired line. This insertion closes the circuit #5 of the relay K and the cut-off relay N by the following path: battery B, 120, K 117,

0 0, 105, pfij', 124, N toground. The

I relay N becoming energized attracts its armatures and disconnects the line relay M 6.0 and connects the line wires 125, 126 to the The relay K in becoming energized attracts its armature and closes the circuit of the supervisory lamp L and places a ground on the contact is of the relay K by the followin path: ground, is, 10 115, 7c. The

suhscriber at station A. upon answering closes his line circuit energizing the relay K extinguishing the lamp L thus notifying the operator that he has answered. At

the end of the conversation the subscriber at station A hanging up opens his line circuit, deenergizing the relay K causing the lamp L to again glow. The subscriber at the automatic station A in hanging up depresses I normal position. These same impulses operate the relays K and K in Fig. 2 in a similar manner. The relay K attracting its armature closes the circuit of the lamp L by the following path: ground, 70 is, 112, 111, L, 109, to battery B and locks itself by the following path: battery B 109, 110, 108, K, 10 70 115, 118, 70 is to ground.

The operator upon perceiving both lamps glowing takes down theconnection, that is withdraws both plugs P, P- from the jacks J, J respectively. The relay K now becomes deenergized extinguishing the lamp L and releases the relay K which in turn extinguishes the lamp L. If the calling subscriber wishes to signal the operator while theplugs are in their respective jacks, he depresses the ringing button which sends in an impulse'over the vertical side of the line operating the relay K which, attracting its armatures, closes the contacts is and is causing the lamp L to flash. This relay K cann'ot lock itself at this time because the contacts 70 and is of the relay K are broken. Su pose the calling subscriber hangs up be ore the operator has placed the calling plug P- into the jack J of the want ed line. Impulses coming in over both sides of the line simultaneously operate both the relays K and K but looking only the relay K by .the following path: battery B, 109,

110, 108, K, e, k, 114, 0 0 119, I610, 16 to ground, The circuit of the lamp L is also closed and the operator noticing the lamp glowing throws her key 0" into the listening position breaking the contacts 0 and '0 releasing the relay K which in turn .extinguishes the lamp L.

It will be seen from the foregoing description that I have provided for any contingency which might arise while the subdisconnect the relays S? pressing the button K he private inagnet .F'

nected to asubscriber in a connnon-battery exchange through a manual switchboard.

I will now describe the operation of that partof my invention wherein a subscriber in subscriber in acommon battery exchange .an automatic. exchange is enabled to 'call a i on the manual switchboard complete the coir nection. This is done by callinggthrough to a connector switch of mytype which I have described. This connector switch cooperates with the selector switches already described in Fig. 1. While I have' made certain changes in the second selector-switch Z enabling me to be connected directly to a manual switchboard it also can perform the ordinary function as in the regular Strowger system by pickingout-the connector switch of the desired hundred. I y

Ihave already described the operation of the first selector switch Z in -connectionwith the first part of my invention and itw'ill not be necessary to repeat it. e will take it for granted that the callingsubscriber is connected through the first selector; switch toa second selector switch of my type. -De- Y sends in impulses over No. 1 side of the line operating; the relay S in the switch Z which in turn closes the circuit of the vertical magnet E by the following path: 'gro'und, s", 8 49. m. 02 ,51}

f 'ffi 47. E" to battery B. This magnet in operating causes the spindle a to step up a row of'contacts leading 'to a connector switch of the desired hundred. The subscriber now depresses the button' K sending an impulse over-No.2 side of the line operating the relay S which in turn closes the circuit of the ground, 8 s, 55, F, 63; 4'5, Thefmagnet F? becoming energized opens the contacts 7?, f disconnecting the vertical magnet E" preventing the spindle", from making. a vertical movement.

by the following path to battery B.

The operat ing-of this relay causes the side switches a,

23?, a, 'to move one point closing the circuit of the rotarymagnetD-which'causes the spindle tov rotate and continue to rotate until the wiper a finds 'a contact free from ground. F becomes deenergized and "the contact of the connector switch upon which the As soon asthishappens the relay' the side switches move another pointdisconnecting the rotary magnet causing the, wipers'to rest on con 'tacts leading to an idle and ground priyate wiper-rests by the follow- 1 mg path: 2 58, X', 57, to ground. The ca ling subscriber is nowconnected .to the connector switch the desired line;

The operation o f the containing the contacts I of .-.of the vertical magnet E pressesthe button K" over No. 2 side of the line operating'the relay N. If I would connected to it visory relays of'the'operators cord circuit on up vertically is much too rapidto cause the lamp L onl-the manual switchboard to glow and as soon as the switch makes asecond vertical movement its, circuitis broken at springs-c -a that is the relay X is' no longer 'connectedto thewire 27. This rapid j movement of the spindle inthe first step is without the necessityof having an operator also too rapid to operativelyenergize the "connected to a. connector switch of the desired hundred, depressesthebutton K sending in impulses over No 1; side of the line operating the vertical relay S which in turn closes the'icircuit of the vertical magnet E by the-following path: ground, S "S 73, f, 7", 72, 2?, 85,13 92, 7S-to batteryB. The operation of this ma net causes thespindle 2 to move up Verticajly bringing the wipers c",- .2 and 2: oppositethe rowcon'tamin'g 4 the COIitaCtS'OftllG desiredline. The subscribernow depresses the-bo tOm K'- sending an impulse o'verNo. 2' side oflirieoperatmg the relay :3 which in turncloses the circuit'of the relay F? by the'following path:

ground, 8*, 8 8 75,"F?,77, tobattery B. This relay opens the contacts f, f. dis,- connecting the vertical magnet E and cansing the side switches 2 2 2 and a to rotary magnet I isnow connected infplace "The subscriber now depresses the butto'nK sending impulses over No. 1 side of the line-operating the re-.' lay Sthe second t-imvwhich now'in'turn .move one point; Inthe side switch-2 the closes the circuit of.'the rotary magnet I the'following path ground, 8 sf, 73, fflf, 72, at, 84, 1 92, 7 8 to battery, B. i This mag-T netinoperatingcauses the spindle to rotate] bringing the wipers to restjon the contacts of the desired line. The subscriber now, de-' sending an impulse lay S which in turn closes the circuit of the relay F as before and at thesame time pla'cing the relay} X 91, to wiper i2 and v y the contact 2 upon which it rests,

Normallythis contact as w'ill be"seen by referringiito the diagram", is"

open being. multip'ledto' p the tip spring of the multiple jacks J J? in a test position by the following, path? ground, 8 s", 76, 2 90, X

and from there to I the normally open c onta'ctyof the cut-off 're= this line was busy. the battery through the superthe manual switchboard, If onjthe other hand" the line was engaged by another coni nector' switch'the' tip supplied 'withbatte'ry, throu retardatioiijcoil which furnishes the battery ppl in 'talk pu re side of line would be. gh the talking or release magnet W restoring theswitch to its normal position. We will take it for granted that the line is not busy; The operation of the private magnet F the second time causes the side switches to move another point. In the side switchle the rotary magnet I is disconnected and the ringing relay Y connected. in. its place. The trunk wires 11 and 12 are connected res ectively to the trunk wipers z" and 2- tirougn the normally closed contacts of the ringing relav Y. In the side switch 2 the circuit of.

the relay X is opened. As soon as the trunk wires of the switch are connectedto the wipers resting on the contacts of the desired line the circuit of the cut-ofi relay N is closed by the following path: battery B, 7 8, 82, one winding of the coil 1, 81, 12, a, 14, y, 3 ,16, 2 18, 20, N to ground. This re lay becoming energized attracts its armatu're, disconnects the relay M and connects the line wires 21 and 22 respectively to the trunk contacts 17 and 18. The calling subscriber is now connected tothe desired party and depressing the button K'which now acts as the rin ing button, he operates the vertical relay path; ground, s s 73, f, f, 72, 2

9, 78 to battery B. This relay becoming energized attracts its armature, disconnects the calling end of the trunkv and connects generator current to the wipers leading to the-desired line. The subscriber in the com mon battery. exchange removin his telephone is supplied with battery i012 talking pur oses through the windings of the retar ation coil 1. The condensers C and. G;

being inserted between the wires 9,11 and 10, 12- prevent battery from flowing back over the trunk operating. the vertical and rotary relays.

At the end subscriber in hanging up. depresses the but tons K and K groundin (both sides of the line simultaneously "whic in the switch-Z operate the relays S and S two relays becoming ener 'zed atthe sametime close the circuits 0 the release magnets'in the connector switch Z and in theisecend selector switch Z" in the following manner:

cit

First the circuit of the release"magne -VV is closed in series through the back release relav X by the, following path battery B,;78, W 87 8 8",. I4, 2 32 58, X, 57, e*,;to ground. -The magnet W? becoming energized restores the switch Z to its normal position. The relay X. becoming fenergized attraetsits armature and closes the cir-' cuit of the release agnet'W by the' following path ound, 412 ,03, 54,53, W, to bat tery B. T is magnet becoming energized restores the switch Z to itsnornial position. In thefirst selectonswitch Z, the vertical and rotary relays S and S are connected permawhich in turn closes the circuit of the ringing relay Y bv the followiig' of the conversation theicalling' nently to the trunk and the impulses coin lllg ll l over both. sides of the line simulta neously energize these relays which close the circuit of the release magnet 'W by the fol:

lowing path: ground,.36, s, s, 34:, f, F. of the relay F ,as-it is ener ized at this time, it), W, 35, to battery B; 1%16 energizing of this relay restores .the switch Z to its normal position.

It will be readily seen from the foregoing description that the second selector switch Z is a combination switch, and performs two functions,v first in connection with a first selector. switch it connects the subscriber directlytoa manual switchboard where he can be connected to any subscriber inthe manual common battery exchange.

The operator at the manual switchboard can also act in the capacity of an information operator in case the subscriber desires some information relating to new subscribers or changes of numbers, etc. Second, this switch can be used as the ordinary second selector switch and connect the calling subscriber directly to a connector switch which is operated in the ordinary manner and enables him to call a subscriber in an automatic exchange jorin picking out a group of selectors of my typehe can call a subscriber in the manual full common battery exchange in the same manner as calling a party in the automatic exchange. v v 1 Having thus described my invention, what Iclaim and desire to secure by Letters Patent of the United States is:

lector switches for interconecting the line.

with other lines as determined by the subscriber, one of said switches permanently associated with and controlled by said subscribersline, a manually operated switchboard having trunk terminals and signals therefor, a trunk-line permanently connected to one of said selector switches accessible by asingle selective operation from the subscribers switch, and to one of said-trunk terminals on the manual board, with means whereby the-said signal may beset and connection obtained througli'the manual switchbeard by a. single operation of the subscribers switching apparatus, and further mean -whereby continued or repe t p rlines without operating ations may eonnectthe line directly to other the trunk signal, substantiallyas described.

3.-In a telephone exchange system, a plurality of subscribers lines and a plurality of automatic switches for interconnecting them as determined by repeated current changes caused-by the calling subscribers, one of sald switches assoclated with. each line and, used as a'first digit selector, a plu-' requiring an appreciable time nal, substantially as described.

4. In a'telephone exchange system, aasubscrib'e'rs line, a first selector switch con-- trolled thereby and-having means to pick out and connect with a, trunk to asecond selector switch, thence to further switching;

means and to subscribers linesfautomatidally, a; permanent extenslon of the trunk troni the second selector to a manually operat'ed switchboard, ajconnective terminal and iISlLIlitl on saidboard for said trunk extension, and means whereby the second se lector switch may be advanced one step to.

display 'the switchboard signal, without clian sing the connection of the trunk, substantially as described. 4 c

In a telephoneexchange'system, a, sub

scribers line, a firstselector switch con-f trolled thereby, and liayingmeans to pick. out and connect with a" trunk'jto a second selector switch, thence to further switching meansand to subscribers"lines automatic;

ally,- a' permanent extensionof the' second se-. lector trunk to a, manually operated switchboard. a connective terminaland a signal,

on said board for said trunk. extension,

means operated in one step of the second select-or switchto set said signal to attract the attention of the operator, and means'controlled by the operator to. release and restore the switch and thereby restore the signal. substantially as described.

(5. In a telephone exchange system, a selector switch having "a releasemagnetop erating to release the switch mechanism,

means to control the switch-as determined by a calling subscriber, and means to select other switches and subscribers lines automatically thereby, a perma11entconnection of the talkingcircuit of the selector switch to a manually operated switchboard and a signal thereon for the same, whereby the talking circuit is complete when a line has selected the said switch without moving-its operating parts, means fordisplaying said signal on actuating the switch,'and means controlled by the operator inanswering the call on the manual switchboard to cut oil and decnergize said release magnet, whereby the switch will be restored and the signal reset, substantially as described.

7. In an automatic telephone exchange system, a second'selector switch, means controlled by a subscriber to connect his line therewith and thence with other subscribers 1 i lines automatically, a back release relay for said switch,-and a release magnet 'cont1 olle d thereby, a'n'extension of the talking circuit of the switch to a manually operatedswitchboard, a -signal on said board associated therewith, a circuit for said signal closed in the first mo'i ement of the switch and including the Saidback release relay to cause the,

initiation of the release movement when the signal'is'dlsplayed, a cut-oft relay for the signal'and release relay circuit, and means actuated by an'operator inanswering a call on the manual switchboard to energize said cut-oil relay, substantially as described.

8. In-anautomatic telephone 'eXcl i ange' system, a selector switch, means controlled by a subscriber to select other subscribers through saidswitch, an extension of the circuit of said switch-tea manuallycontrolled switchboard, whereby a callmgsubs'criber ,can' connect his talking circuit to said manual switchboard without operating theswitch, a signal associated with the extension on the manual switchboard, a circuit for'said signal closed in the first-move;

ment ofthe selectorswitch without affecting the talking-circuit, and a cut-off relay associated with the selector switch controlled by the operator in-answering a 'call on the;

switchboard, and-acting to cut elf the signal and restore the switch, substantially as de scribed. I

9. In an automatic telephone exchange system, aselector switch having a trunk,

means controlled by a subscriber. to connect hisline with said trunk and through the selector switch with other subscribers lines,

an extension of said trunk ."to a manual switchboard, a spring jack thereon and a- 7 signal associated with the trunk extension, a circuit closer for saidslgna-l actuated m cut-off relay in the selector switch connected to a contact in the springjack closedby the operator in answering a call and acting to disconnect the controlling means in the switch to leave a "clear, talking circuit and also meat on the signal, substantially asv described.

10. In a telephone s stem, at second selector switch having ridged controlling the selector switch by the subscriber, and a,

magnets, a trunk accessible to a calling subscriber and connected to give control of said magnets and the switch, an extension of said trunk to a manually operated switchboard with a signal associated therewith, a springjack for the trunk extension, opera tors plugs and cords cooperating therewith, a circuit closer for the signal operated in the first step up of the selector switch, a

release magnet therefor, and a cut-oft'relay in a circuit closed in the jack when a plug is inserted by the operator, whereby the controlling magnets are cut off, the release is operated, and the signal is restored substantially as described. 11. In a=telephone exchange system, a selector switch, controlling magnets therefor after the first impulse repeated im ulses by the subscriber will produce no e ect, substantially as described. 7

12. In an automatic telephone exchange system, selector switches and means con-' trolled thereby to directly interconnect sub scribers lines, an extension from a selector switch circuit to a manual switchboard anda signal therefor, a circuit closer for said signal actuated by the first movement of they switch, means at a subscribers station for sending a rapid succession of impulses to set I up the switch, and means also to send a single impulse to close ,the manual switchboard signal circuit, the succession of impulses being too rapid in every case to set the switchboard signal, substantially as described.

13. A combined automatic and manual switchboard system ofthe type described,

comprising a pair of connective terminals and cord conductors, with three-bridged relays on opposite ends thereof and responding to current in opposite directions to the connected stations, two bridged across one end of the cord with a battery connection from a point between them, the first relay having a circuit whereby upon attraction of its armature it will be self-locking through the listening key of the cord and a normally closed contact of the third relay, the second relay being similarly self-locking through contacts normally open of said relays in the third relay but closed when a connection is completed, substantially as described.

- 14.'In an automatic telephone exchange system, a plurality of selector switches and connector switches working therewith to seminals therein, vertical and rotary relays therein, manual switchboard connections and relays for said subscribers lines, a sensitive test relay, and means controlled by the rotary relay in a connector switch in completing a connection with a called line, to connect said test relay to the testwi er of the said connector switch, whereby di erences of potential on the manually connected lines described.

15. In a telephone exchange system, a subually operated switchboard having trunk line connective terminals and signals associated therewith, connections from said selector switch to said switchboard, means acswitch to display a signal and indicate that board, and means actuated onthe second substantially as described.

lector switch having a release magnet operto control the switch as determined by :11.

thereby, a permanent connection of the talkually -operated switchboard and a signal circuit is complete when a line has selecte the'said switch without moving its operating parts, means for setting the signal and closing circuit tothe release magnet on thefirst step of the switch, means controlled by an operator in answering-a :call to cut oif and denergiz'e the release magnet, and other means controlled in a subsequent step of the switch when making a selection other than ing the same, substantially as described;

in presence of two witnesses.

CHARLES L. ZAHM.

5 Witnesses: g I

Gi-io. E. Hreems, Rm: GARRETT.

tuated in the first motion of the selector a connection is desired on the manual switch-- 'motion orstep thereof to cutoff the same,

calling subscriber, and means to select ptheri switches and subscribers lines automatically ing circuit of the selector switch to a man-,

thereon for the same, whereby the talkin that of the manual operator, to cut oil the release magnet without effectively energizlect and connect with subscribers line termay be detected in testing, substantially as scribers line, a selector switch controlled. thereby having-means to connect the line by*' successive motions with other lines, a man 16. In a telephone exchangesystem, a se-' ating to release the switch mechanism, means In testmmny, whereof I aflix my signature i

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