US1672990A - Telephone system - Google Patents

Description

1,672,990 A, SCHEUNERT TELEPHONE SYSTEM Orrin? Filed June l2. 1924 Sheets-Sheet 2 June l2, `1928.

@Sw N 3 Sheets-Sheet 3 y A. scHEUNERT TELEPHQNE SYSTEM original Filed June 12, 1924 June 12, 1928.y

Patented .lune 12,` `1928.

UNITED lsita-'russ' PATENT OFFICE.

ALFRED scHEUNER'r, or cHAnno'rfrnNBURc, enRMANYQAssIGnoB. To SIEMENS" e@ HALSKE AKTIENGESELLSCHAFT, or WERNERWERK, s IEMENssTADT, NEAR-Jann,-

LIN', GERMANY.

TELEPHONEMSYSTEM.

Application led June 12, 1924, Serial No. 7197568, and in GermanyJune 16, 1923. Renewed November 9,

The invention relates to a circuit arrangement for setting up connectionswith private branch exchange subscribe-rs in automatic telephone systems. It consists in that after a switch has been set on a contact of a line group leading to a private` branch exchange, switching means become operative, which place the positioning members o'f the switch `under the control of switching arrangements belonging to a preceding connecting stage. y The arrangement according to theinvention can. for instance, be usedwith advantage in systems in which connections vof different value may be set up. for instance local and tollk connections.` The switching arrangements which render a switch suitable for effecting special circuit changes that only required forfhigh valueconnections are, for instance, not associated with the `switches over which the subscribers lines are reached but are associated with other preceding switches, ofwhich only a small quantityfare provided." In that case the invention enables the positioning members of a switch to be controlled by devices associated `with the switch itself in the case of low value connections; but for high value connections the positioning members are controlled from the point provided with switching means for converting the switch.

The drawings comprising Figs. `l-4, inclusive, show by way ofexainple one method of carrying out the invention.

Fig. l shows diagrammatically the arrangement of theswitches 'for setting up local and toll calls in a telephone system. Fig. 2 .showsy the calling end `ot" the toll operators cord FA *provided with the calling plug Fat, an outgoing line accessible at the jack KZ and terininating in the preselector IFVVV, and the first groupselector IGVV. The detail circuits ot the above have been omitted since they do not concern the invention. y y

In Fig. 3 is shown by means of thefnsual circuit diagrams the second HGVVfcL and IIGWfb. c 1

In Fig.`4 is shown the final selector LW. Local connections betwee-nthe subscribers TZn l and Tla 2 are setup by positioning group selectors the following switches: first preselector LVW, second preselector ILVV, first local group selector LGWO. second local groupselector ILGVVo and final selector LW.

back contact al;` second toll group selector ILGVV/u, final selector LWlto subscriber If "the subscriberfl'llw). is `Wantedby the tollexoliange, the operator at the" toll eX- change FAplugs into` a 'free jack KZ withV lher plug Fst. itself in known manner on a free succeedf The preselector `LFVW sets in switchcnamely on a first group selector I. Wj that can onlybe used for toll 'connections. This "first group selector, by

means of number impulses, is set on a particular contact group and then in this group seeks a free second toll group selector, namethe lpair of group selectorsILGWfa and ILGWf). Bothgroup selectorsgare simultaneously positioned. A free final selector LWis taken-into use over the group selector lllGWfa. The final selector having `been positioned, the switch ILGWfa is disl connected and the switch IILGVVfb connected up. This `is "effected by switching over suitable contacts, one of which 1s shown in Fig. 1 and` is designated by u1. The .final lsettingup of the toll connectionv and of the speaking routetakes selector IIGWfb. y p y @The different yconnections that can be set up over the group "selectors Il GWfa and ILGWI) will now be described. y

The casewill firstbe `considered.`in which place Aover the group a local connection is to be set up Withthe v direct` line subscriberTM, 2 and in which this local connection must extend over a toll group selector IIGWfa owing to all second group selectors ILGlVo arranged only for local calls being engaged.

The individual circuit changes will now be explained with reference to Figs. 3 and 4.

Vhen the pair of roup selectors II.GVVfa and ILGWfb are ta en into use by a preceding first group selector, a circuit is closed over the test wiper of this first group selector, this circuit extending from earth over the test relayl (not shown) of the first group selector, the test lead 1, the ofi-normal con-l tact 2 cf'a. and the windings I of the relays B1 and C1 and battery to earth. The relays B1 and C1 operate. The relay C1, by closing its contact 3 c1, prepares a holding circuit over both its windings I and II. By the opening of the contact 4 c1, the release magnets M1 and M2 are disconnected and in place thereof the circuit of the rotary mag nets Dl and D2 is prepared at the contact 5 c1. At the contact 6 c1 the test relay P1 is connected to the test Wiper 7 of the group selector IIGWfa. `The relay B1, which was energized at the same time as the relay C1, at its contact 8 b1 connects the impulse receiving relay A1 to the lead 9 and at the contact 10 bl connects its second winding II B1 to the lead 11. Furthermore, by closing the contact 12 b1, it prepares the circuit of the vertical magnets H1 and H2 of the group selectors IIGWfa and IIGWfb. By the opening of the contact 13 b1, a premature connecting up of the rotary magnets D1 and D2 is prevented. When thc calling station transmit-s impulses for positioning the second group selector, battery potential is connected to the lead 11 `in known manner at a preceding impulse repeater and thereby the relayV Bl/is maintained energized for the duration the Winding I of the relay of the train of impulses. Impulses are transmitted over the lead 9. The relay A1 is energized ateach impulse and at the contacts 14 a1 and 15 al closes the circuits of the vertical magnets H1 and H2: earth, contacts 12 b1 and 14 c1, vertical magnet H2, battery, earth. The off-normal contact 2 cfa is opened at the first vertical ste and thereby y 1 is disconnected. Furthermore the oil' normal contacts 16 kf@ and 17 rfb are closed. At the end ofthe train of impulses, battery is disconnected from the, lead 11. thereby de-energizing the vrelay B1. This closes its contacts 13 b1, hence the rotary magnets D1 and D2 of both the group selectors are now energized. The circuit for the rot-ary magnets extends as -t'ollows:-earth, contact 13 b1.l contact 16 fa and in parallel therewith contact 17 kfb. contacts 18 p1, 5 c1, 19 al. rotary magnet D1. battery earth and parallel thereto contact 20 a1, rotary magnet D2, battery,earth. When both rotary'magnets have operated, the relay A1 is locally energized: earth, contacts 2l d1, 22 (l2, relay A1 battery,'earth. The relay A1 opens its contacts 19 a1 and 20 al, so that the rotary inagnets D1 and D2 are (le-energized. Both the group selectors have been moved on one step and the relay A1. on releasing, again closes its back contacts 19 al and 20 a1. Thereupon the rotary magnets D1 and D2 can again energize and close the circuit for the relay A1. which again opens the circuits of D1 and D2. The intermittent opening and closing of the circuits of the driving magnets Dl and D2 causes the two group selectors to be synchronously operated.

vWhen a free iinal selector LIV is found, the following test circuit is established: earth, windings I and II of the test relay P1, contact 6 c1, wiper 7, contact 23, lead 24, side switch contact 25, (Fig. 4) position 1, winding I of the relay C2, battery, earth. The relays P1 and C2 operate. The relay P1 at contact 18 [11 (Fig. 3) opens the. circuit of the rotary magnets D1 and D2`y marks the selected final selector engaged by short circuiting its highresistance winding I at contact 26 Pl and at contacts 27 p1 and p1 it switches through' the speaking leads 9 and 11 over the back contacts 29 u1 and 30 u1. the leads 31 and 32. theuwipcrs 33 and 34, the contacts 35 and Bti to the leads 37 and 3S extending to the filial selector LlV, where the bridging relays A2 and B2 are connected up over the side switch contacts 39 and 40 (Fig. 4) in the positions 1 and 2 ofthe side switch.

The relay C2, operated at the same time as the relay P1, by closing its contact 41 prepares a holding circuit` which functions when the side switch leaves its position 1. The relay C2 furtherniore opens and closesy a number of other contacts. over which however circuit changes onlytake place at later stages'in the setting up of the connection.

When the calling party transmits current impulses for setting the final selector on a particular contact `group the control relay B2 is energized by the application of' battery potential to the lead 11. The relay B2 opens its contact 42 b2 and thereby prevents the side switch moving on prematurely into the position 2. Impulses are sent over the leads 9. 31 and 37 and operate the impulse receiving relay A2. This at each impulse closes the circuit of the vertical magnet H3: earth, contact 43 a2, side switch contact 44 position 1 vertical magnet H3, battery, earth. yAt the end of the train of impulses, the dis connectionof battery potential from the'lead 11 causes the release of the relay B2. which at its contact 42 b2 closes the circuit ofa' f relay F2 :V earth. contacts 42 b2, 45 (L2, 46 k3. side switchycontact'47 position 1, relay F2, resistance 48, battery, earth. T he relay F2 at its contact 49 f2 connects up the sideI switch magnet St, which at its contact 5() st short circuits the relay F 2. Thereby the side switch lis moved into the second position, in which the rotary magnet D3 is connected up in place oif the vertical magnet H3. i During the second train of impulses which serve to set the tinal selector on aV particularline, the relay B2 is again energized and opens the contact 42 b2. The impulses, which are received by the relay A2, operate the rotary magnet D3 in the following circuit: earth, contacts 511. p2, 52 g, 53 (r2, side switch con` tact 55 position 2, rotary magnet D3, battery, earth. At the end of this train of impulses the relay B2 airain releases and closes the circuit ot the relay F2, which connects up the side switch magnet S/f earth, contacts 42 b2, Li5 a2, 56 zo?) (closed on the tlrst rotary step of the switch), side switch contact 57 position 2, relay F2, resistance Llt, battery, earth. The side switch moves into its po. ltion 3, in wl'iich `the 'relay lll; is energizcd over the contaets4-2 b2 and i5 a2 and the side switch contact tlposition i `and causes the side switch to more on into the position 4. In position 3 o'f the side switch a relay U2 is energized over its winding l: earth, side switch contact 59 position 3, winding I of the relay U2, i 'stance 48, battery, earth. The relay U2 is provided with a slow releasing; armature, so that the. contact (i0 u2 remains open a little while 'after the circuit of the relay U2 has been opened. i i

In position 4 the free or engaged condition of the wanted line is tested. It will first be assumed that the wanted line is idle. In that case the following test circuit is established: earth, contact 6l yf, side switch contact 62 position et, windings I and II o'f the relay P2, wiper 63, contact G41-, relay 65 associated with the wanted line, battery, earth. Therelay P2 operates and marks the selected line engaged `by short circniting its high resistance winding I at contact 66 p2. Furthermore at contact `67 ,r2 it opens the circuit of the release magnet M3 and at contact 5l p2 it 'opens the circuit of the rot-ary niagnetDS. 4This switching operation is required for a connection describedlater on. f

When the relay U2 has released, the relay F2 is energized in the following circuit: earth, contacts GS a2, 6() u2, side switch contact 69 position 4t, `relay F2, resistance 48, battery, earth. The relay F2 in the manner already described causes the side switch `to move on into the position 5. `Since theselected line is freeiand the relay P2 has therefore been energized, the relay F2 is energized as follows in the position 5 of the si de switch: earth, contact 7() p2, side switch con tact 71 position 5, relay F2, resistance 18, battery, earth. The `side switchY therefore nieves to position 6. In this position the first call is transmitted to the selected line:

`leases and elo `the cont-act yo c1. The opening of this conearth, `source of ringing current 72a, side switch contact 73 position 6, wiper 74, contact 75, lead 76 of the snbscribers line, subscribers instrument Tln. 2, lead 77 of the snbscribers line contact 78 wiper 79, side switch contact 80 position 6. earth. In the position 6 ot the side switch the relay F2 controlling the side switch magnet St is connected over the side switch contact 8l position 6 to a slow interrupter 82. The side switch is moved on into the position '7 with the assistance of the interrupter S2 andin this position 'further calling takes place.` A relay L2 is repeatedly energized as follows over an interrupter (10 second switch): earth, contact 83 n2, side switch contact 84e position 7, ringing` relay L2, 10 second switch 85, battery, earth. Each time the ringing relay L2 operates, ringing current is transmitted as follows: earth, source ot ringing current 72b, contact 86 1. windingr II oi" the relay U2, side switch contact 87 position over the wipers and thev selected subscribers line back over the side switch cont-act 8() position 7, earth. The callingparty receives a ring back tone in positions (5 and 7 oit the side switch, since a buzzer Su 1 is connected to the windings II ot the relays A2 and B2 over the side switch contact 93, positions 6 and 7. During each ringing' pause battery isconnectcd up over the back contact 88 Z2.

lV hen the wanted subscriber answers during a ringing,r pause, the removal of' his receiver establishes a direct` current path, in which `the relay U2 can be energized `by its winding II. The relay U2 opens the contact 83 'M2 and prevents a furtl'ier energization of the relay L2. It also closes its `contact 89 n2, thereby energizing the relay F2 in the following circuit: earth, contacts'Q() e2, 89 n.2.,side` switch contact 91 position 7, relay F 2, resistance 48, battery, earth. The side switch reaches its position 8, in which the speakinirleads are switched through over the side switch contacts and f 93. The bridging relays A2 and B2, which now torni the feeding;r bridge ol" the selected subscriber', operate over the subscriliiens line. The relay A2 opens its contact 90 a2 and thereby prevents the `side switch moving on :l'rom the po.,r tion 8 into the position 9.

When the wanted subscriber hangs up at vthe end ot the conversation, thc relays A2 and B2`areide-energized so that the side switch moves on into theposition 9, since the relay FZ is energized over: earth, contact il() a2, side switch contact 92 position S relay F2, resistance 4 8, battery, earth.

y then the cal ing;` party also hangs up, the circnitover the lead l (Fig. 3) leading,r to the secondgronp selector is opened in lrnown maniicr. rl"he relay Cl thereiipon res its contact f t cl and opens tact interrupts the circuit over the relays P1 and C2 (Fig. 4). The relay P1 (Fig. 3)

closes its contact 18 p1, thereby connecting up the release magnets M1 and M2 of the group selectors lLGWfa and ILGWfZ): earth, contacts 13 b1. 10 ffa and 1T fb, 18 p1, e1 c1, magnets M1 and M2, battery, earth. Both group selectors return to .their normal position, in which the off-normal contacts l0' /cfa and 1T kf?) are opened and the off-,normal Contact 2 /cfa is closed. The group selectors can now be taken into use for another connection.

At the final selector (Fig. 4) the interruption of the current flowing over the lead 24 causes the relay C2 to release and opens its holding circuit at the contact 41 It thereupon causes the side switch to move from the position 9 into the position 10, since the relay F2 is energized over the contact 94 c2 and the side switch contact 95 pozition 9. In position 10 the relay F2 is energized over the contact 90 a2 and side switch contact 92. Vhen the side switch reaches position 11 the winding 1I of the relay P2 is short circuited over the side switch contact 96, so that relay P2 releases. The circuit of the release magnet M3 is now closed: earth, contacts 9T c2. 67 p2, side switch contact 98 position 11, release magnet M3. battery, earth. The final selector therefore returns to its normal position, in which the of-normal contact 99 le?) is closed. The side switch is now moved on from the position 11 into the position 1, because the relay F2 connected up over: earth, contacts 94 c2, 100 p2, side switch contact 101Y position 11, off-normal contact- 99 k3. relay F2, resistance 48, battery, earth.v The final selector has now been completely restored to normal.

If the line of the selector subscriber Tln were engaged, the relay P2 would not have been energized in the position 4 of the side switch. Hence the side switch will remain at present in the position because the contact 70 p2 has not. been closed. Over the side switch contact 102 position 5 an engaged tone is connected to the relays A2 and B2, so that the caller is notified that the wanted line is engaged.

lVhen the caller hangs up, the second group selector is released in the manner described. whereupon at'ter the release of the relay C2 the release magnet M3 is connected up over the Contact 97 c2 and the side contact 1.03 position 5, and returns the final selector to its normal position. After the release of the final selector, when the off-normal contact 99 7a3 is closed, the relay F2 is energized over the contact 91 c2. the side switch contact 104 position 5 and the off-normal contact 99 lf3. The side switch is moved into the position 6 and thence into the position 7 by means of the interrupter 82 connected up over the side switch contact 81. The relay F2 is now energized over the Contact 105 02 and the side switch contact 91 position 7. In the positions 8 and 10 of the side switch the relay F2 is energized over the contact 90 a2 and the side switch contact 92. In position 9 the relay F2 is energized over the contact 94 c2 and the side switch contact 95 and in the position 11 it is energized over the contacts 94 c2, 100 p2, side switch contact 101 and oft-normal contact 99 7c3.

The case will now be'considered, in which a connection is being set up to a private branch exchange. After the final selector has been set on the first contact of a P. B. X. it is necessary to select a. free line going to the P. B. X. At the end of the train of impulses for setting the final selector on a particular Contact, the side switch reaches the position 4 in the manner described. The first contact allotted to a P. B. X. subscriber at the filial selector is a blank contact, to which no line is connected. The side switch momentarily remains in the position 4, because the slow releasing relay U2 was energized in the position 3. At the final selector a contact 54 mic is provided, which is closed as soon as the final selector is set on the blank contact of a P. B. X. Uver this contact the relay A2 is energized: earth, contacts 51 p2, 52 g, multiple contact 54 mk, side switch Contact 106 position 4, relay A2,

resistance 107, battery, earth. The relay A2 connects up the winding I of the slow releasing relay U2: earth, contacts 108 a2, 109 b2, Winding I of the relay U2 resistance 48, battery, earth: hence the rela U2 is maintained energized and the site switch remains for the present in the position 4. Furthermore the relay A2 also closes its contact 53 a2 and thereby connects up the rotary magnet D3: earth, contacts 51 p2, 52 g, a2. side switch contact 55 position 4, rotary magnet D3, battery, earth: the final selector is therefore moved on t0 the next line. At the same time, however, the magnet D3 at its Contact 110 i3 short circuits the relay A2, which releases and by opening the Contact 53 a2 interrupts the circuit of the rotary magnet D3. The rotary magnet D3 releases, removes the short circuit round the winding I of the relay A2, so that this can again operate and can again close the circuit of the rotary magnet D3. This cycle is repeated until a free line to the selected P. B. X. has been found. Thereupon the relay P2 operates, and by opening the contact 51 p2 prevents the relay A2 and the rotary magnet D3 being again energized and it also efii'ects the other operations described for a connection with a direct line subscriber. As the contact 108 c2 is no longer closed, the relay U2 releases after a little while. The relay F2 is then energized over the contact u2 and moves the side switch into the position 5. The further setto the l. l5. K. it cornes to rest on this con` tact even though this line be engaged. This is achieved because the contactl 'httpdocs not remain closed when the s'witi-zh is Vset on the last contact oi a l. l1. llheycircuit changes occurring" when the `last P. B.l X, line is engaged are the saine those occurring when it is set on an engaged line o1l a direct line subscriber; hence this condition need not be described. i y i A description will now .be given of the cir cuit changes that occur when toll connections are set up. The case will first becon-` sidcred in which direct lineV subscriber, namely the subscriber T/n 2 is called by the toll exchange. ln known manner `the `toll operator (FA) with the tip of the plug Frs-t (Fig. 2) tests the jacks lil oi" the outgoing lines to see which are idle; (.)nlinding an idle line, she inserts the plug into the corresponding jack thereby cloeiini,` the followingl .fircuit: Vearth, battery, re:-:ista1'ice 1.11, rplug contact 112, ack bush l 1.3, relay CF 1, earth. The relay CF1 in known manner starts up the preselector `IFVW associated with the jack, and the switch `sets itself on "a free` succeeding numerical switch, for instance 1.171117'. Aitcr the preselector hasbeen po` eitioned, a circuitis established over,V its` r Wiper 111-1-, which eiiergizesthe relay CF 2',

which then at contact `.L (172 connects irth to the test relay 13 After the lgroup selector LGlV/i has been raised to a particular level by a train ol impulses transmitted by the operator, the switch hunts tor a free line in the selectedcontact group. When this has been found, the following circuit is estal'ilished i earth, contact 115 cj2, relay P3, wiper 111i, contact 1.17, lead113 to. Fig. 3, lead l, contact2 11,711, windinglv of the relay :11. winding l of the relay (11, battery, earth. The relay 153 at the contacts 119 and 12() p3 (Fig. 2) in known manner switches through` the speakii'ig leads.

Thesetting of the second group selectors H GrlvVfa and lLGVVf?) on to a particular contact` group, the selection of a tree final selector LW' and ythe ignositioning of the lat ter on the contact o'lthe wanted sl;ibscribei"s line Tlfny 2 effected in the manner described for a local connection.

At the end oi the train ot impulses for setting the final. selector' on the contact ot the wanted line., 'when the side switch reaches the position 3, the relay B2 is energized inthe following circuit because battery is automatically connected lo one lead by theoperators impulse sender: earth, battery,` i1npulse sen der Nu! `in the cord circuit to the operator (Fig. 2), contacts 1121, 121 and 122,

tip 123 of the plug Fst, jack spring 124, l

Wiper 125, contacts 126, 119 p3, Wiper 127,

contact 128, lead 129 to Fig. `3, lead 9, con` tacts 27,101, 29.171, lead 31, wiper 33notthe groupl selector ILGWfa, contact 35, lead 37 to Fig. 4, contact 130 g, side switch contact 131..position 3, Winding I of the 1elay`B2. The relay` B2`opens its contact 42 b2 and thereby prevents the side switch` being moved beyond the position 3. Vllurthermore the relay VB2 energizes relay G in the followmg circuit: earth, contacts 132 52,133 f2,

side switch contact 134 position 3, `relay G,

battery, earth. The relay G 33 operates and at contact 130 y opens the circuit for enen gizing the relay B2, which however closed relay G was connected up: earth, winding I of relay B2, side switch contacts 131 and .135

position 3, contact 136 b2, lead 137, contact 138 (Fig. 3)` and wiper 139 o1' the group Selector lllGw'b, contacts 1410 p1, 141 f1, winding of the relay U1, battery, earth, When the relay Grv at the final selector operated, it locked itself at its contact 142 g in a holding circuit, which remains closed in the positions 3-5 of the side switch. At the second group selector the relay U1` operates and connects itself at contact `114 yn1 in the following holding circuit: earth, contacts 143 c1, 1411 u1, winding 1I of the relay U 1, battery, earth. The relay U1 disconnects the speaking leads 31 and 32 and the wipers 33 and 34 of the group selector ILGVVfa `from the incoming line by opening the contacts 29 u1 and 30 u1. and switches the incoinin line over to the group selector ILGl/YJ at the contacts 145 'n1 and 146 u1. The test relay P1 Which is connected to the test wiper 7 of 11.(irlV/a is not disconnected however and maintains the group selector 1n its, operated position.

The connection to the wantedv subscriber `has now been so tar set up that the toll opof the plug Fat, jack spring 151, wi per 152,

contacts V153 and 120 p3, wiper 154, contact 155, lead 156 to Fig. 3, lead 11, contacts 28 p1, 146 u1 and 157 S1, relay F1, battery,

earth. The relay F1 operates and opens the holding` circuit o'it the `relay B2 at Vthe final selector (Fig. 4), which circuit extends over the lead 137, the wiper 139 andthe windingI of the relay U1.` The relay B2 releases and causes the. side switch to move on into the position 4, 1n position 3 of the side switch the relay U2, having a slow releasing armature,

was also energized, as explained in the de scription of the local connection: hence the side switch momentarily remains in the position 4. When the relay U2 has released, the side switch moves into the position 5, in which it remains until the release of the con nection. All the switchin devices for effecting the special circuit c anges that only occur 1n toll connections are associated witi the pair of roup selectors Il GWfa and II.GWfb. T e testing to ascertain whet-her the selected subscriber s line is free or locally or' trunk engaged is effected by test relays of these group selectors. It should now be mentioned that a slow acting relay V1 is connected up when the relay U1 is'energized earth, contacts 158 u1, 159 w1, relay V1, battery, earth. The relay V1 at the contact 16() c] repares the circuit over the winding I of t e relay X. When the relay F1 operates, owing to the actuation of the test key PT, the circuit is closed for the slow acting relay X1: earth, contacts 160 lv1, 161 f1, relay X1, Winding I, battery, earth. At its contact 162 m1 the re lay X1 connects the relay O1 to the wiper 164 of ILGVVfb, thiscircuit having been prepared over the contact 163 c1 by the relay V1. The relay O1 is not operated for calls to direct line subscribers.

The relay X1 also connects the test relay HB1 to the test wiper 139. The test circuit extends as follows: earth, relay HB1, contacts 165 01, 166 l, 167 hr1. 168 o1, 140 p1, wiper 139, contact 138, lead 137, contact 169 b2 (Fig. 4), test wiper 63 of the final selector, contact 64, relay 65, battery, earth. The

relay HB1 tests whether the line is toll engaged. Only if it is toll engaged does the relay not operate, since in that case earth is directly connected to the contact 64, but the relay operates if the subscribers lineis free or is locally enga d.

If the selected subscribers line is toll engaged, the toll operator receives a buzzer `Slgnal, which' is connected up as follows:

earth, induction coil 17() (Fig. 3). contacts 171 f1, 172 hr2, condenser 17 3, contacts 174 hr1, 17 51 winding II-o'f the relays E1 and F1, battery, earth. The buzzer signal is repeated to the toll operator by the relays E1 and F1 and she is notified that the wanted line is toll engaged. n

If. however', the selected line is not engaged by a toll call and the relay HB1V scribers line is free. Ifthe selected line locally engaged,the relay HB2 cannot operate. Hence the buzzer circuit for the locally engaged signal is closed as follows: earth, induction coil 179, relay B1, contacts 18() hr1, 17 51 windings II of the relays El and F1, battery, earth. The relay B1 operates in this circuit and closes its contact 181 1-1 thereby connecting the relay HB1 in parallel with the relay HB2. Thus two toll connections are prevented from being simultaneously connected through to a line. Until the existing local connection has been released over the switch shown in the draw ing, another toll operator can set up a toll connection over other switches and from them can immediately release the local connection. Thereupon earth is directly con-iv ne'cted to thecontact 181 at another final selector LW (Fig. 4) as is shown dotted. Hence current is withdrawn from the relay HB1 and it releases and gives the toll operator the toll engaged si al. V

If the subscribers line 1s free, the relay HB2 (Fig. 3) operates as described above and locks itself in aholding circuit over its winding II: earth, contacts 182 hr2, 140 p1, 183 kr2,'winding II of the relay HB2, battery, earth. But over the Contact 182 hr2 earth is also directly connected to the test .contact 64 of the select/ed line, hence the latter is completely blocked to other connections. This circuit extends as follows: earth, contacts 182 hr2, 140 p1, wiper 139, contact 138, lead 137, contact 169 b2 (Fig. 4) wiper 63, contact 64, relay 65, battery, earth.

To call the wanted line, the toll operator presses the release key TT (Fig. 2) and thereby applies battery to one speaking lead, namely t e lead to which the relay Elat the second group selector is connected. The circuit extends as follows: earth, battery, contact 184 of the release key TT, plug tip 123, jack spring 124, wiper 125, contacts 126 and 119 p3, wiper 127, contact 128, lead 129 to Fig. 3, lead 9, contacts 27 p1, 145 u1, 185 s1, re ay El, earth. The energizing of the relay E1 causes theringing relay L1 to be connected up: earth, contacts 186 f1, 187 hr2, 188 s1, 189 e1. 190 r1. ringing relay L1, battery, earth. The ringing relay L1 is energized at each operation of the release key TT, it opens its contacts 191 and192 11 and at the contacts 193 11 and 194 1l connects ringing current to the speaking leads. It

remains to be mentioned that when the relay lil) instrument T207, 2, lead 77, `contactl, wiper 79, contact 202 u2, lead, 203,contact 204 (Fig. 3), wiper 205, contacts 19d/W2 and 194 1 earth. i i

When the wanted subscriber answers, the feeding j bridge relay `S1 operates and by kopening the contact 18S s1 preventsthe relay L being again connected up. The relay S1 also, by opening the contacts 185 s1 and 157 s1, interrupts the circuit containing the relaysEl and F1 of the second group selec-` the operator that the wanted subscriber has answered.` l i y Whenthe wanted subscriber hangs up at i the end of the conversation, the relay S1 is cle-energized and closes its'contacts 157 s1 and 18551; Hence the relay SB (Fig 2) in the toll operators cord circuit is energized together with the relays El and Fl (Fig. 3). The relay SB connects up the clearing lamp SL, thereby notifying the operator that the (.:onversation has finished.

The release of the connection etfected by withdrawing the plug at the tollposition,

whereby the relay CF is de-energized. This then opens the existing circuit over the wiper 1,14, causing the relay CP2 at the nrst toll group selector to release.

relay P1 (Fig releases and at contact 18 p1 closestlie circuit for the release magnets M1 and M2: earth, contacts 13 b1, 16 cfc,

and 17 .7c/fb, 18 p1, 4 c1, release magnets M1,`

and M2, battery, earth. Both group selectors are thereupon released.

` The .side switch ol the tinal selector (Fig. 4) stands in position 5 for toll connections as above explained. Upon the release of the relay C2 the release magnet M3 is connected up over the side switch contact 103 position 5 and releases the final selector LW. When the iinal selector' has reached its normal posi-- tion, the oif-nornial contact 99 7c3 is closed.

` The relay` @F2 opens its contact 115 @f2 whereupon the` i lines to the P. B. X..

switch contact 104 position 5, oiinornial.`

contact 99 7c3, relay F2, resistance 48, battery, earth. )Vlien the side switch reaches the position 6, the relay F2 is energized over the side switch contact `81'. and interrupter 82. In the further` positions of the side switch the relay F2 is energized as follows: in position 7 over thecontact105 c2 and the side switch contact 91, in )osition S over the contact 9U a2'and side switch contact 92, in

the position 9 over the contact 94 c2 and. `the side switch contact 95, in position 1l) over the contact 9() a2 and in position 11 over the contacts 94 c2, 100 p2, side switch conn tact 101, off-normal contact 99 c. The side switchis thus returned to its normal position(position Y Y i yIfthe selected subscribei"s line locally engaged, this being indicated to the operator by a buzzer signal as above described, the operator can speak to the subscriber, because the speaking leads have been switched through over the condensers l235 and 236 (Fig. and the contacts 237 c1 and 238 el. and 239 w'l. `and 240 hr1. After the subscribers have been notified of the operatoids intention to disconnect their local connection, the release key '.lT is pressed and thereby the relay El energized in the saine manner as when ringing current is connected up. The relay E1 opens the contacts 237` e1, 238 e1 and 241 e1 and closes the contacts 242 `e1 and` 243 e1. VAt the last mentioned contacts earthis connected to both speaking leads and thereby the release of the local connectionis brought about in known inanner. The relay HB2 operates when the local connection has been released, because the contact 176 hr1 stillreinains closed. The relay HB2 short circuits the relay HB1 at the `contact 177 laf/'2 and switches through the speaking leads at the contacts 197 hr2 and 198 hr2. It the wanted subscriber has hung up, he is called in the same manner as when the line is free. i

Itiwill now be assumed that a toll call is As previously mentioned no line is connected to be set up with a P. B. subscriber.

to the irst contact o1 a first P. X. subscriber, this blank contact being for preliminarily testing Whether there are any free 1t is assumed that the contact 22() (Fig. 4) is the blank contact in Afront of the line group leading to a P. B. X. Earth is connected to this contact so long as there is a line still idle. When all the lines to the P, B. X. are engaged, the relays 65 I, 65 I1, etc. associated with these lines, are en ergized either by outgoingor incoming calls. Over the contacts 221./65 I, 222/65, II,

etc. a relay V4 is connected up, which, by opening the contact 223 o4, disconnects earth from the blank contact 220.

The contact 54 mk is closed at the same time when the final selector is seton the blank contact 220. lVhen the. relay B2 releases at the end of the train ol impulses for setting the final selector on the blank contactot the wanted P. B. X. the side switch is brought into the position 3 in the manner described. In this position the relay B2 is again energized over the lead'', the contact 130 g and the side switch Contact 131. The relay B2 keeps the side switch in the position 3, because the contact Ll2 b2 is opened. Furthermore in position 3 oi the side switch the relay UQ is energized over the side switch contact .59. The relay Ul at the sec ond group selector is now again energized over the lead 1.37, the contact 136 b2 and the winding I of the relay B2. The relay U1 then connects` up the relay V1.

When the toil operator presses the test key PT (Fig. 3) the energizing of the relay F1 (Fig. 3) opens the circuit over the relays U1 and B2. The relay B2 releases and the side switch reaches the position Ll. Here. it remains because the relay U2, which was energized in the position 3, is provided with a slow releasing armature. The energizing of the relay F1 causes the relay X1 `to be energized by its winding l over the contact 161 f1 and furthermore the Contact 9.28 f1 is also closed. Testing now takes place to ascertain whether any lines to the P. B. X. are free. If there are any free., the

' relay O1 is energized over its winding I follows: earth, battery, winding 1 of the re lay O1, contacts 163 2:2,162 :121, 195 hr2, wiper 164` contact 200, lead 201, wiper 74 (Fig. 4), blank contact` 220, contact 223 nel., earth. The relay O1 operates and opens the short circuit round its holding winding II at the contact i226 01. At the same time, however, the following circuit is closed: earth, contacts 228 f1, 225 el, windings ll and III otl the relay X1, winding Il ot' the relay Ol, contact Q99 hr1, 196 hr2, wiper Q01, lead Q03, contacts 230 u2 (Fig. 4), g. 54 mit. side switch contact 106 position 4, relay AQ, resistance 107, battery. earth. The relay A12 operates and the relays X1 and O1 are maintained energized. T he relay A2 closes its contact 53 (z2 and thereby connects its own winding in parallel with the rotary magnet D3. The latter cannot operate, at present however. owing to the high resistance winding l] oit' the relay X1. The relay' AQ, by closing the contact 16S (12, maintains the relay U2 energized, so that the side switch remains in the position 4 since contact 'u2 remains open. As the relay O1 is energized, the relay HB2 is connected to the test wiper 139. Testing for a free line now takes place.

lVhen the slow relay V1 at the second group selector has released after its circuit was opened at contact 159 :n1 upon the energization of the relay X1, the high resist-- alice winding Il of the relay X1 is short circuited at the contact 231 lvl. Thereupon the rotary magnet DB (Fig. 4) can be energized by earth connected upover the contact 327 :rl (Fig. 3). The rotar magnet D3 moves the tinal selector on to tie next contact, and at the contact 110 d3 short circuits the relay A2, which opens the contact 53 a2. The rotary magnet D3 releases. This cycle is now repeated until a free line is found whereupon the relay H122 operates, and locks itselt up over its winding II and the con.- tacts 182 hr2. 140 p1, and 184 k12 and at the same time marks the selected line toll engaged hy applying earth over the contact 18;! 'fr/'2. 1 Y

lt may happen that While hunting tor a tree P. B. X.y line is taking place, the last vtree line taken into use by another party. When the tinal selector reaches the last line, the contact 54 m: is opened, thereby releasing` the relays O1 and X1. The relay X1 is, however, rendered slow releasing owing to 'the winding Il being short cireuited, hence the contact 166 afl remains closed a little while utter the contactl 165 01 has vbeen closed. If the. last line is locally engaged therefore, the relay HRI operates and at its' contact 18() lil-'1 connects up a buzzer, which notities the toll operator that the line is locally engaged. 1n order that the toll operator can communicate with the speaking subscribers, the speaking leads are switched through by the relay HRl in the manner de scribed for setting up a toll call to a direct line subscriber. Also the local connection is released and the. toll coi'mection finally set up in the same manner. If, however, the line toll engaged, the relay HR-l cannot operate and the operator receives the toll engaged signal over the contact 174 rrl.

It there are no free lines when the linal selector' is set on the blank contact, earth is discennected from the contact 220 and the relay O1 therefore cannot Operate. Hence the relay l-lRl. remains connected to the test- '.rl, 167 hr1, 168 o1. and 140 p1. It operates as soon as the final selector LW reaches a locally engaged line, stops the final selector by opening the circuit over the relays Xl` and A2 and gives the locally engaged signal to the toll operator. The release of the local connection and the calling and the release ot the switches at the end of the conversation take place in the manner described tor a toll connection to a direct line subscriber.

.ln the examples shown it is assumed that there are two group selectors lLGWfa and ILGV), connected in parallel each of wiper 1259 over the contacts 165 o1, 166' which has separate driving and release mag-v nets. Instead of having two switches, however, it is obvious that one switch with two sets of wipers can be used, both the sets of wipers being mounted on the same shaft and arranged to wipe over different Contact banks.

What l claim is :4-

l. In a telephone system, means including a selector and a rotary connector for extending a connection to the first idle line in a group, means in said connector including an impulsing relay and a stepping magnet controlled by said impulsing relay for giving its wipers a hunting movement, and means in the selector for controlling said impulsing relay.

2. In a telephone system, means including a selector', a trunk line and a rotary connector terminating said trunk line `for extending a connection to the first idle line in a group, means in said connector for giving its wipers a hunting movement, and means in the selector controlled over a nontalking conductor of said trunk line for stopping suc-h hunting movement when an idle line is found. i

In a telephone system, means including a selector and aconnector for extending a connection from a calling line to a called line, means in the selector for testing the connected called line to determine if' the sameis busy or idle, and means controlled over the calling line after the connection is established for starting the testing operation at will.

4. In telephone system, a combination toll and local connector for extending a connection to a called line, toll and local selectors for extending toll and local calls to said connectors, respectively, means in said combination connector forNtesting a called line effective in case the connector has been seized by a local selector, and testing means in each toll selector so that in case the connector is seized by a toll selector thecalled line is tested from such toll selector.

5. In a telephone system, a group of lines, any number of which may be idle, locall busy, or toll busy, a first automatic switc having access to said lines, a second automatic switch, means 4for operating said second switch to connect with said first switch, means for operating said first switch to successively connect with the first idle line providing one exists, or the first locally busy line providing none of the lines is idle` and one of the linesis locally busy, and means in. said second switch for controlling said second means.

6. In a telephone system, a group of lines, a first automatic switch having access to said lines, a second automatic switch, means for operating said second switch to connect with said first switch, a first and a second trunk terminating in said second switch, means controlled over either' of said trunks for operating said first switch into selective relation with said lines, means for then operating said first switch to successively connect with said lines, testing means in` said first switch rendered effective when the operation of' said first switch is controlled over one of said trunks, and testing means in said secondy switch rendereifl e'ective when the operation of said `first switch is controlled over the other of' said trunks.

7 In a telephone system, a group of lines any of which may be idle, engaged in a toll connection, or engaged in a local connection, a first automatic switch having access to said lines, a second automatic switch, means for operating said second switch to connect with said first switch, means for operatinor said first `switch into selec-tive relation with said lines, means in said first switch for giving its wipers a hunting movement, testing means in said second switch for controlling the hunting movement of said first switch sensitive to idle lines, second testing means in said second switch for controlling the hunting movement ot said first switch sensitive to locally busy lines or idle l'inesmeans for placinor the hunting movement Linder the cont-rol of' said first testing means in case there is an idle line available, and for placing said hunting movement under the control of' the other' testing means in case all of said lines are busy. i

8. In a telephone system, a group of lines any of which may be idle, engaged in a toll connection, or engaged in a local connection, a first automatic switch having access to said lines, a second automatic switch, means for operating said second switch to connect with said first switch, means for operatinor said first switch into select-ive relation with said lines, testing means in said second switch, andv means controlled by said` test-ing means for causing said first switch toconnect with the firstk idle line in Asaid group providing there is one idle, or connect with the first locally busy line in said group providing all of said linesare either toll or locally engaged. Y

9.. `In a telephone system, means including a selector and a rotary connector :for extending connections to a line in a group, means in said connector for giving its wipers a hunting movement, testing means in said selector, and means under the control of said testing means for stopping such hunting movement when an idle line isfound providing there is an idle line in the group, and means for stopping such hunting movement when a locally engaged line is found providing all said lines are either toll or locally engaged.

10. In a telephone trunking system, combination tolly and local connectors, combination toll and local selectors having access to said connectors, discriminating means in each combination switch for causing it to operate differently in toll and in local connections and local selectors also having access to said connectors.

11. In a telephone trunking system, toll first selectors and local first selectors, combination toll and local second selectors accessible to said toll first selectors and to said local first selectors, local second selectors accessible only to said local first selectors, and combination toll and local connectors accessible to said toll and local second select/ors and to said local second selectors.

12. In a telephone system, a rotary con* nector having a controlled directive movement and an automatic hunting movement for extending a connection from a calling station to an idle line of a group, an impulsing relay in said connector, a stepping magnet in said connector under the control of said relay, means for operating said relay responsive to and in accordance with the calling device `at the calling station for controlling the directive movementof said connector' and means for utomat-ically operating said relay to contro* said hunting movement.

13. In a telephone system, a subscribers line which may be either idle, engaged in a local connection, or engaged in a toll con* nection, means including a selector and a connector for extending a connection to said line, and means in said selector for testing said line to determine whether the same is idle, is busy in a local connection, or is busy in a toll connection.

14. In a telephone system, a group of lines any one or more of which may be idle, locally engaged, or toll engaged, an automatic switch, and means for operating said switch to select an idle line of said group providing one of saidlines is idle and for operating said switch to select a locally engaged line providing all the lines of said group -are either toll engaged or locally engaged.

15. In a telephone system, a group of lines any one or more of which may be idle, locally enga-ged, or toll engaged, an automatic switch, means for operating said switch into selective relationwith said lines, and means automatically operative thereafter for causingsaid switch to selectv the first idle line of said group providing one or more is idle, or the first locally busy line of` said group providing none of the lines is idle kand one or more is locally busy.

16. In a telephone system, al group of lines any one ormore of which may be idle, locally 17.5111 a telephone system, a group of lines any one or more of which may be idle, locally engaged, or toll engaged, an automatic switch, means for operating said switch into selective relation with the lines of said. grou successively, and means for stopping sai operation when an idle line is reached or when a locally yengaged line is reached providing none of' the lines of said group is idle or when the last line of the group is reached providing all the lines are toll engaged.

18. In a telephone system, a group of lines any one or more of which may be idle, locally engaged, or toll engaged, an automatic switch, a trunk comprising talking conductors and a non-talking cond terminating said switch, means controlled over one talking conductor for operating said switch into selective relation with the lines of said group successively, and means controlled over said non-talking conductor for stopping said operation when an idle line is reached, or

wihen a locally engaged line is reached providing none of the lines is idle.

I9. In a telephone system, a grou of lines any one or more of which may be id e, locally engaged, or toll engaged, an automatic switch, means for operating said switch into selective'relation withsaid lines successively, a first test. relay responsive when an idle line is reached for stopping .said operation, a second test relay responsive when a locally engaged line. is reached for stopping said operation,l and means for determining which of said relays is to lgovern the stopping of said operation.

20. In a telephone system, agroupof lines any .one or more of which may be idle, locally engaged, or toll engaged, an automatic switch having line wipers and a test wi er, means` for operating said wipers into selective relationy with said lines successively, aV first testv relay responsive when controlled over said test wiper when an idle is reached for stopping said operation, l. second test relay responsive when controlled over said test wiper when a locallv engaged line is reached for `stopping said operation, and means controlled over one of said line wipers for determining which ofsaid relays is to be controlled over said testwi er.

In testimony whereof Iv my signa-ture.

ALFRED SCHEUNERT.

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