US1742920A - Telephone-exchange system - Google Patents

Description

Jan. 7, 1930. w, H 155 1,742,920

TELEPHONE EXCHANGE SYSTEM Filed June 20, 1928 8 Sheets-Sheet 2 Q or lNVENTOR WILL/AM 1?! Aarmlcs ATTORNEY Jan. 7, 1930. w. H. MATTHIES TELEPHONE EXCHANGE SYSTEM Filed June 20, 1928 8 Sheet-Sheet ma /w ,4 TTORNE) Jan.7, 1930. w. H. MATTHIES TELEPHONE EXCHANGE SYSTEM 8 Sheets-Sheet 4 Filed June 20, 1928 1 WRQF 1 wvmron M/ILL/AM h. MTTH/ES ATTORNEY Jan. 7, 1930. w. H. MATTHIES 1,742,920

I TELEPHONE EXCHANGE SYSTEM Fild June 20, 192B 8 Sheets-Sheet 5 v /NVEN7'0H Q: w W/LL/AM h. MA TTH/ES ATTORNEY Jan. 7, 1930. w. H. MATTHIES TELEPHONE EXCHANGE SYSTEM FiledJune 20, 1928 8 Sheets-Sheet 6 INVENTOR WILL/AM h! MITTH/ES A TTOHNEY Jan. 7, 1930. w. H. MATTHIES 1,742,920

TELEPHONE EXCHANGE SYSTEM Filed June 20, 1928 8 Sheets-Sheet 7 INVENTOR W/LL/AM hf MA TTH/ES Y A TTORNE Y Patented Jan. 7, 1930 UNiTED .ST TES PATENT OFFICE WILLIAM H. MATTHIES, 0F HACKENSACK, NEW JERSEY, ASSIGNOR TO BELL TELE- PHONE LABORATORIES, INCORPORATED, 015 NEW YORK, N. Y.,' CORPORATION OF NEW YORK TELEPHONE-EXCHANGE SYSTEM Application filed. June 20,

This invention reiates to a telephone 'exchange system employing automatic selector switches and more particularly to a system employing a repeating sender associable with the incoming ends of interofiice trunks, to which the numerical portion of a wanted line number is transferred from the subscribers sender and which in turn controls the setting of the selector switches at the terminating oilice. The invention has for its object the more accurate control of selector switches over long interofiice trunks and the simplification of apparatus for repeating control impulses from one sender to another.

In large machine switching telephone exchanges it often occurs that certain ofiices of such exchanges are located at the outskirts of such areas and that therefore long interoffice trunks are necessary to interconnect certain offices which may be quite widely separated. Under these conditions the revertive control of panel type selectors over such long trunks is not always reliable since the fixed speed at whichthe selectors at the terminating office operate on local connections may be faster than can be accurately controlled from a sender in an originating oliice, especially where a long length of interoffice cable intervenes. I-Ieretofore, it has been the practice to establish such connections through a tandem switching otiice, the digits registered on the sender in an originating office being first transferred to a sender in the tandem office, which latter sender then controls the setting of the selectors in the terminating office. Unless the exchange area is very large and comprises a large number of oflices, such tandem ofiice-s are not warranted from an economic standpoint and direct trunking between oflices of the area is desirable.

, A tandem trunking system of the type above described is illustrated in the patent to VJ. L. Dodge, No. 1,531,080, issued March 24, 1925. In this system the oiiice and line designations registered on the registers of the sent er in the originating office are transferred to the registers of the tandem sender by the so-called relay call indicator pulse method. That is, for each digit registered in the first sender a special code of impulses of negative 1928. Serial No. 286,842.

and positive polarity is transmitted to the tandem sender which is arranged to receive and register such codes on relay registers in much the same manner as impulses are transmitted to and registered in the well known call indicators. For local calls of a full mechanical nature the originating sender functions in the well known manner to control selector switches by impulses set to the sender revertively by the selectors. Since such tandem senders must perform substantially all of the functions of the senders in the originating oiiice, they must of necessity be as com plicated in structure and function as such originating senders.

In accordance with the present invention calls from originating oiiices may be trunked directly to terminating oflices without extension through a tandem oflic e. Th'is'is accomplished through the provision of a group of small repeating or so-called spill senders in each office, accessible in common to all interoflice incoming trunks. Each of these senders comprises a means for sending trains of revertive impulses back to the originating sender in the same manner that impulses are revertively sent from a selective switch commutator to satisfy the originating sender in accordance with the line designation digits registered on the registers thereof. The registers of the repeating sender are set in accordance with the impulses of each train so sent and therefore assume settings equivalent to the settings of the registers of the sender in the originating oifice. Counting relays are also provided which count the impulses so transmitted and assist in the setting of the registers and also in the usual manner count the impulses later transmitted from the selectors of the terminating oflice to control the setting of such selectors in accordance with the setting of the sender registers. I v

The apparatus of the repeating sender is thus very simple and since it controls the transfer of registrations to its registers revertively in the same manner as selectors control their own settings, it is not necessary to employ special call indicator code apparatus in originating senders for this purpose but the same apparatus employed in the originating senders for setting selector switches may be employed. Further, since there is no fixed speed of impulsing established such as is present in pulsing revertively from selector. switches, the speed of impulsing from the repeating sender to the originating sender may be made such as is more suitable for pulsing over longer interoffice cables than could be used for controlling selectors originating office in which the calling line termimtes. When. a call is incoming to an incoming selector in which an interofiice trunk terminates a start circuit is closed to start a pair of trunk finders individual to an allotted repeating or spill sender of a group serving the group of trunks in which the seized trunk is located, in search of the selected trunk. When one of the trunk finders finds the calling trunk a circuit is extended fromthe sender, over the 'interoffice trunk, to the sender in the originating ofiice. Series of impulses are thereupon sent back over such established circuit from the spill sender to the originating sender in simulation or" usual action of commutators of inco-nr ing and final selector switches. In response to these series of impulses the registers of theoriginating sender are satisfied and incoming: brush and group, and final brush, tens, and unitsregisters of the spill sender are set into correspondence with the similar registers of the originating sender. A fundamental-switch controlling circuit is then established between the spill sender and incomingand final selectors of the terminatingofiice Such selectors are controlled from the spill sender in much the same manner as theyqwould be controlled from the crigi nating sender in accordance with the prior art. As soon as the-originatingsender has 1 completed the transference of its registra- .5. com-ing and final selectors it is also dismissed.

, The invention has been disclosed by way of illustration inthe accompanying drawings in which Fig. I shows diagrammatically afcall- .ing line terminating in an automatic dial switching oilicfe: having a line finder, district selector, oilice selector and common sender;

Fig;v 2- showsz-a-nincoming selector of a terminating officeof-the exchange: Fig.3 shows a final selector; of such terminating ofiice and 1 one subscribers line terminating therein;

of the four subgroups of senders; and'Fig. 9

shows the manner in which the figures of the drawing should be assembled to completely disclose the invention.

The apparatus of the originating oflice disclosed in Fig. 1 may be of the type fully disclosed in the patent to .F: A. Stearn No. 1,505,171, granted August 19, 1924.

The trunk finders510 and 520 of'the spill sender, shown in Fig. 5, may be of the well known panel type with the exception that each finder is provided with'but a single set of brushes and no tripping mechanism is provided. Two sequence switches are provided for controlling the spill sender. One of these sequence switches has a driving magnet 500 shown in Fig. 5. All the cams shown at the left of the dot and dash line of Fig. 5 and all of the cams shown in Fig. 6 with the exception of cams 605, 631, 633 and 638 are operated by magnet 500. The other sequence switch whose magnet is shown at 550 of Fig. 5 controls all of the cams shown at the right of the dot and dash line of Fig. 5 and earns 605, 631, 633 and 638 of Fig. 6.

Extension of connection to spill sender It is believed that the invention may be best understood from a detailed consideration of the manner in which a callmay be established from the line ofsubscriber 100 in Fig. 1

to the line of subscriber 325 inFig. 3. For thispurpose it will be assumedjthat the number of subscriber 325 is CORtlandt 3983. When the calling subscriber removes his receiver from the switchhook his line becomes extended by means of the line finder 101 to the district selector 102 and through link mechanism not shown to an'idle'sender diagrammatically illustrated by the rectangle 103. The line finder 101, district selector 102, sender 103 and link mechanism may be of the type disclosed in the patent to W. H. Matthies No. 1,567,072 granted December 29, 1925. A sender of the type disclosed at 103 is shown in detail in the patent to O. H. Kopp No. 1,589,402, granted June 22, 1926.

Upon the extension of the calling line to the sender'a pulsing circuit is established extending from battery, winding of pulsing relay 104, the left contactof cam 105, the ring brush of line finder 101 and the line terminal with which it is in engagement over the subscribers line loop, returning over the tip" brush of line finder 101, the left contact of cam 106 to ground through the left winding of coil 107. Relay 104 energizes in this circuit, closing an obvious circuit for relay 108 which in turn establishes a tone circuit from the source 109 through the right winding of relay 107, the left contact of relay 108 to ground. A tone is thereby induced into the pulsing circuit and is heard by the calling subscriber apprising him that he may commence to dial the office and numerical designations of the wanted line. In the manner fully set forth in the aforementioned patent to Kopp, in response to the manipulation of dial 110, the office code and numerical registers of the sender are set to record the number of the wanted line. As soon as the office code has been registered and the proper translation has been made in the sender, the sender proceeds in the well known manner to control the setting of the district selector 102 to extend the calling line to the terminals of an idle oflice selector 150. The control of this selector is exercised through the operation of the sender stepping relay 112 in conjunction with the usual. train of counting relays, the last pair of which 113 and 114 are disclosed, and with the translator of the sender, not shown. As soon as the district selector has found an idle office selector such as 150 the district sequence switch advances to position 10 in which position a controlling or fundamental circuit is extended from the sender to the oflice selector which may be traced in part from the tip brush of the district selector 102, the right contacts of cam 115. the back contact of counting relay 113, the winding of stepping relay 112, the upper left and lower right contacts of-cam 116, to the ring brush of the district selector. The office selector 150 which is of the well known type is then set from the translator of the sender to complete the extension of the calling line to the offi-ce in which the wanted line 325 terminates.

Upon the seizure of conductors 201 and 202 of an idle trunk terminating in the incoming selector 250, the previously traced fundamental circuit is extended from the tip brush of the selector 102, over the tip brush of selector 150, conductor 201, the lower right contact of cam 203, resistance 204, to battery through the right winding of relay 205 and from the ring brush of the district selector 102, over the ring brush of oflice selector 150, conductor 202, the lower left contact of cam 206, to ground through the left winding of relay 205. Relays 112 and 205 energize in this circuit, relay 112 preparing the sender for controlling the transfer of the incoming brush registration from the sender 103 to the sender of Figs. 5, 6 and '7. lVith sequence switch 200 in position 1, relay 205 upon energizing establishes a circuit for control relay 207, extending from battery, right winding of relay 207, upper left contact of cam 208,

front contact of relay 205, right back contact of relay 209, to ground at the lower contact of cam 210.

Relay 207 energizes in this circuit and closes a start circuit for associating an idle sender with the trunk circuit 201, 202. This circuit extends from ground at the left front contact of relay 207, the upper right and lower left contacts of cam 211, start conductor 212, the upper back contact of relay 400, the left back contact of relay 401 to battery through the left winding of relay 402, provided there is an idle sender in the subgroup of senders normally assigned for serving the trunks in which trunk 201, 202 is located. Relay 402 upon energizing extends the start conductor 212 over the upper back contact of relay 400, the outer right front contact of relay 402 to conductor 403, the outer left back contact of relay 501, the upper contact of cam 502, to battery through the right winding of relay 503 and resistance 504. Relay 503 upon energizing closes a circuit for advancing se quence switch 550 out of position 1 into position 2 extending from battery, Winding of sequence switch magnet 550, the upper left contact of cam 505 to ground at the right front contact of relay 503. With sequence switch 550 in position 2 relay 503 is locked from battery through resistance 504 and the as follows: battery, winding of up-drive -magnet 511, the lower left contact of cam 509 to ground at the right front contact of relay 503. In response to the energization of magnet 511, the brushes of switch 520 are ad-' vanced to the first set of terminals connected to the first trunk of the group to which this trunk finder has access. It will be assumed that this trunk is in a non-calling condition and that the control relay thereof corresponding to relay 207 is deenergized. When the brushes of switch 520 are centered on the first set of terminals, the locking circuit of relay 503 is opened at the'commutator strip 507 as the brush 508 is then resting on an insulating segment thereof, but relay 503 is maintained energized over a locking circuit extending from battery at the upper right contact of cam 600, conductor 601, the left winding and inner left front contact of relay 503, bridging type test brush 512 and the terminal upon which 1t is resting, over a conductor similar to conductor 513 thence over the left contacts of a cam similar to cam 213 to ground at the back contact of the control advanced beyond position 1, then the conducto'r 513 would-"be grounded at the lower left contact of a cam similarto cam 214 and relay 503 would remain locked. With relay 503 thus-locked the circuit of the up-drive magnet 511i ismaintained' to advance the brushes of switch 520 to the next set of terminals.

It will be assumed thatthe next set of terminals is connected as shown to the trunk 201, 202' and that the test conductor 513 is therefore open both at the back'contact of relay 207 and at the contact ofcam 214. Re-

. 'tial upon the terminals upon which it is resting therebypreventingthebrushes of another trunk finder associated with. another sender finder from. connecting therewith.

Relay 503 at its outerright back contact also establishes a circuit from ground over the inner right back contactof relay 501, the upper contacts of cam 517, conductor 404 to battery through the winding of relay 401. Relay 401 upon operating opens the start circuits through the windings of relay 402 to prevent the starting of another pre-allotted trunk finder until after the started trunk finder has found the calling trunk. With sequence switch 550 inposition 3 acircuit is closed to advance sequence switch 500 out of position 1 into position 2' extending from battery through the winding, of magnet 500, upper left contactof cam 514" to ground over the upper left and lower right contacts of cam 515. A circuit is also established from ground at the outer right backcontact of relay 503, the inner right back contact of relay 501, the lower contact of cam 516, the uppercontacts of cam 516 of a sender similar to the one disclosed whose sequence switch corresponding to 550 is standing in position 18 awaiting allotment, thence to the lower right contact of a cam similar to 505 to battery through the magnet of such sequence switch advancing such sequence switch into position 1 in readiness for serving the next incoming call.

At its inner right back contact relay 503 establishes a circuit extending from ground at the outer right back contact of relay 501, inner right'back contact of relay 503, upper left contact of cam 518, brush 519, and the terminal upon which it is resting, conductor 405., upper contact of-cam 215, winding of relay 209tobattery. Relay 209 energizes opening at its right back contact the circuit of relay 207 which in turn deenergizes",;opening the circuitzthrough relay 402, and at its right front contact closes a circuit for advancing sequence switch 200 out of position 1 into position 2. This circuit may be traced z from battery through the winding of magnet 200, lower left contact of cam 216, rightfront contact of relay 209, to ground at the lower contact of cam 210. W'Vith sequence switch 200 in position 2, ground is placed on conductor 513 atthe lower left contact of cam 214 to mark the incoming selector and associated trunk as busy before all sender. trunk finding switches having access thereto.

When sequence switch 200 left position 1 the windings of relay'205 became disconnected from the, tip and ring conductors 201 and 202 of the trunk and relays 112 and 205 became dee'nergized. The fundamental circuit'is now extended from trunk conductor 201 over con ductor 217, brush 521, the lower right and upper left contacts of cam 522 tov battery through the winding of control relay 523 and from trunk conductor 202 over conductor 218,

left front contact to ground at the lower right contact of cam 527, closing a holding circuit for itself directly to ground over its right front contact and the front contact of relay 523 to prevent its deenergization after sequence switch 500 leaves position 2, and closinga'circuit over its left front contact, upper right front contact of cam 514 throughthe winding of sequence switch 500 for advancing sequence switch 500 into position 3.. With sequence switch 500 in position. 3 the shunt which normally exists around relay 529 is removed at the left contacts of cam 527 and relay 529 energizes over the fundamental circuit. Setting the sender registers Two circuits are now effective in parallel with each other, the first extending from bat: tery over the left contact of cam 60 0through the winding of the N o. 9 counting relay of the train of counting relays disclosed at the contacts of cam 603. The second circuit ex tends from ground on conductor 604 over both contacts of cam 530 to battery through the winding of relay 532. Relay 532 and the No. 9 counting relay energize, the No. 9 count-- ing relay locking through the winding of the No. 9 counting relay, the front contact of the N0. 9 counting relay, the lower contacts of cam 605 to ground at the lower contacts of cam 606. The number 9 counting relay, however, does not energize in this locking circuit since at this time both of its terminals are connected to ground. Relay 532 upon energizing closes an obvious holding circuit for relay 523 in shunt of relay 529 and also in shunt of the sender stepping relay 112. Both of these relays thereupon deenergize, the stepping relay 112 causing upon its energization and deenergizaton the operation of a pair of counting relays of the sender 103 in the well known manner. Upon the deenergization of relay 529 ground is removed from one terminal of the No. 9 counting relay and this relay energizes in the locking circuit of the No. 9 counting relay. Thus a pair of counting relays in both the sender 103 and in the spill sender shown in Figs. 5, 6 and 7 have been operated and locked.

Upon the deenergization of relay 529, the energizing circuit of relay 532 is opened and the shunt again removed from the windings of relays 529 and 112 and these relays again energize, the relay 112 operating another counting relay of the next pair in the train of sender 103 and relay 529 again closing the circuit for operating relay 532 and in parallel therewith the No. 8 counting relay, over a circuit extending from conductor 602 through the front contact of the No. 9 counting relay, the back contact of the No. 8 counting relay through the winding of the No. 8 count-- ing relay to battery over the circuit previously traced. Relay 532 and the No. 8 counting relay energize, the No. 8 counting relay locking through the winding of the No. 8 counting relay and relay 532 again shunting the stepping relay 112 and the relay 529. This cycle of operations continues until the originating sender 103 is satisfied as to its in coming brush selection registration whereupon the fundamental circuit 1S opened at the sender 103 and relay 523 deenergizes.

Relay 523 up deenergizing opens the hold ing circuit ofrelay 528, which. later relay cleenergizes closing a circuit from battery through the magnet winding of sequence switch 500, the lower right contact of cum 514 for advancing sequence switch 500 into position 4:. It has been assumed that the number of the wanted subscriber 325 is 3983.

' Thus, two pairs of counting relays, No. 9 and No. 9 and No. 8 and No. 8 have been operated and locked to cause a registration of the fact that it will be necessary to trip the second set of brushes in the incoming selector 250. The manner in which this registration is set up on the incoming brush register relays of Fig. 7 will now be described.

When sequence switch 500 passes into posicontact of cam 606. Until the No. 9 counting relay energizes, a shunt around the right winding of relay 700 exists which may be traced from the junction of the two windings of relay 700 over the left back contact of relay 700, conductor 703, the upper left and lower right contacts of the cam 608 to the back contact of the No. 9 counting relay to ground at the lower contact of cam 606. As soon as the No. 9 counting relay energizes relay 7 00 energizes.

A circuit is also established for relay 7 05 extending from battery over the lower contact of cam 600, conductor 701, both windings of relay 705, conductor 706, the left contacts of cam 609, the back contact of the No. 6 counting relay, the lower contacts of cam 605 to ground at the lower contact of cam 606. Until the N0. 8 counting relay energizes there is a shunt around the right winding of relay 705 which may be traced from the unction of the two windings of relay 705 over the inner left back contact of relay 705 and conductor 707, the left contacts of cam 610, the back contact of the No. 8 counting relay to ground at the lower contact of cam 606. This shunt is opened at the back contact of the No. 8 counting relay when that relay is energized and relay 7 05 thereupon energizes.

A circuit is also established for relay 710 extending. from battery, conductor 701, through both windings of relay 710, conductor 708, lower contact of cam 611, back contact of the No. 41 counting relay to ground as traced at the lower contact of cam 606. This relay, however, does not energize since its right winding is shunted over its outer' right back contact, conductor 709, the right contacts of cam 612, the back contact of the No. 5 counting relay to ground at the lower contact of cam 606 and, since the No. 5 counting relay has not been energized this relay "710 cannot operate. Thus, in response to the operation of the counting relays two incoming brush selection register relays 700 and 7 05 I have been operated and when sequence switch 500 advances into position 4 locking circuits are established therefor. The locking circuit of relay 7 00 may be traced from'battery, conductor 7 01, through both windings and the inner right contact of relay 700, conductor 7 04- to ground at the upper left contact of cam 606. The locking circuit for relay 705 may betraced from battery on the conductor 701 through both windings and the inner right contact of relay 705, conductor 704 to ground at the upper left contact of cam 606.

It will be recalled that upon the termination of the transference of the incoming brush registration from the sender 103 .to the spill sender that sequenceswitch 500 advanced into position 4. The fundamental circuit is 110w reestablished from battery through the winding of relay 523 thence as traced to the winding of relay 112 at the sender 103, returning overthe right back contact of relay 526 to ground at the upper left contact of cam 527. Relay 529 is at this time shunted at the left contacts of cam 527. Relay 523 upon energizing over the fundamental circuit again operates relay 528 which locks .as before de scribed and closesa circuit from ground over its-outer left front contact and the .upper contact of cam 514 for advancing sequenceswitch 500 into position 5. Relay 528 remains locked over the contact of relay 523 and its own right contact aftersequence switch 500 lea-ves position 4. Theoperated counting relays No. 9, No.9, No. 8 and N0. 8' are at .this time released as their locking circuits were opened at the lower contacts of cam 606 when sequence switch 500 passed out of position With sequence switch. 500 in position 5, the shunt around the winding of'relay 529 is removed and this ,relaycnergizes over the fundamental circuitclosing the previously traced parallel circuits through the winding of relay 532 and the winding of the No. 9 counting relay.

In the manner previously described relays 523, 529 and 112 cooperate to successively operate and lock pairs of counting relays in operationwof relay, 113, releasing relays i523,

the spill sender and inthe sender 103 until suflicient counting relays in the-sender 103 have been operated to satisfy'the incoming group registration therein, when the fundamental circuit will "be opened through the 529 and 112. The release of relay 523-in the manner previously described opens the holding circuit of relay 528 which releases and causes the advance of sequence switch 500 into position 6. Since it has been assumed that the subscribers line number is 3983, it

'will be necessary to select. a groupof final selectors terminating in the fourth group of the second brush group of the incoming selector and therefore, four pairs of counting. relays, No.9, No. 9, No. 8, No. 8, No.7, No.

7 and No. "6, No. '6 will be operated during the transference of theincoming group registration in the manner previously described.

As the sequence switch 500 passesinto position 5, the following Icircuits will :be established for operating relays of the incoming group register: the first clrcuitextends from battery at the lower contact of cam 600 over conductor 701, through both windings of re-1 ilay 711,-conductor 712, the lower contacts of cam 607, the back contact :of counting relay No.- 7, the lower contacts :of cam 605 to ground at the lower contact of cam 7606.

Until the No. 9counting relay energizes the right winding of relay 711 is-shunted over a circuit from the junction point between the windings of relay .715, conductor 716, the

lower contacts of cam 609, the back contact of the No. 6 counting relay to ground at the lower contact of cam 606. Until the No. 8 counting relaylenergizes, relay 715 is shunted in acircuit from the junction point between the windings of relay 715, the inner left back contact of relay 715, conductor 717, the upper right and lower left contacts of cam 610, the back contact of the No. 8 counting relay to ground ajttlie lower contact of cam 606. As soon as the No. 8 counting relay energizes this'shunt-is opened and-relay v715 operates. When the No. 7 counting relay operates the operating circuit of relay 7-11 is opened at the :back contact of the No. 7 counting relay and relay 711 deenergizes. As soon as the No. '6 counting relay operates the circuit of the relay 715 is opened at the back contact of the No. 7 counting relay. Thus, when the sequence switch advances out of position 5 into position 6 at the end of the transference of the incoming group registration, no relays of the incominggroup register remain oper-' 112 of the sender 103. In the manner previ- V V ously described relay 528 operates and locks upon the operation" of relay 523, advancing sequence switch 500 into position 7and thereby including relay 529 in the fundamental circuit. Counting relays of the spill sender and of the sender 103 are thereupon operated and locked in the manner previously described until the sender 103 is satisfied as to its final brush registration when relay 1 13 operates, opening the fundamental circuit at the sender 103. Thereupon relays 112,523 and 529 are deenergized, relay 523 unlocking relay 528 which in turn deenergizes advancing sequence switch 500 into position 8. Since it has been assumed that the subscribers number is 3983 the terminals of the wan-ted line will appear in'thefifth brush group of the final selector and therefore five pairs of counting relays from No. 9 No. 9f

to No. 5, No. 5' inclusiye will .have been operated.

out of position 7 a circuit will be effective from battery on conductor 701 through both Prior to the advance of sequence switch 500 windingszof final brush register relay. 718, conductor 719,-the upper right and lower left con-' tactsof-cani- 607 the back contact of the No. 7 counting -,relay, the lower contacts of own 605 to ground at the lower contact of cam 6%. Until the No. 9 counting relay operates a shunt exists around the right winding of relay 718, extending from the junction point between its windings over the left contact of 10 .relay 718,conductor 720, the right contacts of cam 608, the bacl; contact of the No. 9

counting relay to battery. As soon as the- No. .9 counting relay operates this shunt is opened andrelay 718 operates. A circuit is also closed from battery on conductor 701, through both windings of relay 721, conductor 7 22,.the upper right and lower left contacts of can1.609, the back contact of the No. 6-

counting relay, thence to ground at the lower contact of am 606. Until theNo. 8 counting relay operates a shunt exists around the right winding of relay 721 extending from the unction pointobetween its windings over the inner left back contact of relay 721, conductor 723, the lower contacts of cam 610, the back contact of the N o. 8 counting relay to ground at the lower contact of cam 606. As soon as the No; 8 counting relay operates this shunt is opened andv register relay 721 operates. A circuit. is also established from battery on conductor 701, through both windings of re lay 724,]conductor 725, the lower contact of cam 613, the back contact of the No. 3 counting relay to ground at the lower contact of cam .606, and a shunt around the I right winding of relay 72% exists from the junction of itstwo windings over its right back contact, conductor 726, the lower contacts of cam 612,1the back contact of the No. 5 counting relay to ground at thelower contact'of cam 606. This shunt is removed when theNo.

5 counting relay energizes and relay 724 thereupon operates.

As soon as the. No. 7 counting relay energizes the operatingcircuit of relay 718 is opened [at the back contact of this counting relay and relay 718 releases. Theoperation of the No. 6 counting relay-also opens the operating circuit of relay 721 at the backv contact of the No. 6 counting relay and-relay 721 ;releases.- Thus at the end of the trans-.

tact of cam 606 and as the sequence switch arrives in. position 8 relay 523 is again opere atedover the fundamentalcircuit in series with "relay-112' .of the sender; 103. Inthe manner previously described relay 528 Opera atesand locks uponthe operationeof relay; 523,ladvancing sequence switch 500 into poa sition9 and-thereby includingrelay 529 in;- the fundamental circuit. Counting.- relays of the; spill sender and'of the sender l03 arethereupon operated and locked in :themanner-previously described'untilthe sender 103- is satisfied as to its final'tens registration. when relay 113 operates" opening the funda-;

mental circuit at the sender 103a Thereupon relays 112,523 and 529 deenergize,-z-relay 523 unlocking relay 528. which in turn deenergizes; advancingsequence switch 500 into position- 10. Sinceit has been assumed .that the wanted dine-terminates in the ninth group of thefifth brush group of thezfinali selector, all

of the, pairs ofcounting relays from No.29,

upper right contact of .can1p614, the lower right contact of can1608, the'back contact of;v

the No. 9 counting relay. togroun'dat the lower contact of cam 606. As soon asthe'No.

9 counting relay operatesthis;shuntis opened and relay .728 energizes... A circuit is. also closed frombattery on conductor. 701;.through both'windings of. may? 31, conductor 7 32, q

the. upper-left'contact of ca1n613, the back contact: of the No. 3 countingrelayto,ground at the lower contact of can ..606. Until the 1 No.8 counting relay. operates a .shuntexists 1 around the right. winding .of. relay 7 31,..eX a tendingcfr'oin the. unction between .its. windings over its inner left back contact; con-n vductor 733, the lower leiftl'contact of 021111 615,...

the lower left contactv of. cam -610, the. back contact ofthe No. 8 counting relayto groundat thelower contact of ca1n.606. :Assoonas the, No. .8 counting relay operates this shunt is opened thereby and relay 731 operates. j 1 A circuit is also established from battery on. conductor. 701, through .bothwindings of. r lay 73 i, conductor 735, the, leftcontact of; cam. 616, theback contact of the No. 2 counting relay to. ground. at thelower contact of cam 606. Until, the. No. 7 countingrelay operates a shunt exists .aroundthe right winding of re lay. 734,.extendiiig from the junction between the windings thereof,.over the inner leftback contact of relay 734:, .conductor 7 36,-the upper: left; contact. of earn. 617, the lower .left. cont;- I tactof cam'.607, .the-baclncontact of-the No.1

.. 7 counting relay te-ground atitheebackcon-s 4 3 the back contact of the No. 1 counting relay to ground at the lower cont-act of cam 606. Until the No. 6 counting relay operates a 10 shunt exists around the right winding of relay 737, extending from the junction between the windings thereof, over the inner left back contact of relay 7 37 conductor 739, the upper left contact of can1'6l9, the lower I left contact of cam 609, the back contact of the No; 6- counting relay to ground at the lower contact of cam 606. As soon as the No. 6 counting relay operates this shunt is opened and relay 737 energizes. Still another cirzolcuit may be traced from battery on the conductor 701, over both windings of relay 740, conductor 741, the upper contact of cam 620, the back contact of theNo. 0 counting relay to ground at the lower contact of cam 606.

Until the No. 5 counting relay operates the right winding of relay 740 is shunted in a circuit extending from the junction point between the windings thereof, over the inner left back contact thereof, conductor 742, the

so upper left contact of cam 621, the, lower right contact of cam 612, the back contact of the No. 5 counting relay to ground at the lower contact of cam 606. As soon. as the No. 5 counting relay operates this shunt is removed I and relay 740 operates.

When the No. 4, No. 3, No. 2 and No. 1 counting relays operate, previously traced operating circuitsfor relays 728, 731, 734 and 737 are opened atthe back contacts of such Am -counting relays and therefore at the time sequence switch 500 advances out of position 9 into position 10 only one register relay 740 of the final tens register remains, operated. This relay locks from battery on'conductor 4'01, through both of its windings and its inner right front contact, conductor 743, to

7 ground at the lower left contact of cam 603 as soon as sequence switch 500 reaches position 9 Upon leaving position 9 the -locking circuits for all operated counting relays are opened at the lower contact of cam 606 in readiness for the registration of final between the windings thereof, over its inner 7 units impulses. V 7

With sequence switch 500 in position 10 relay 523 is again operated over the fundamental circuit in series with relay 112 of the sender 103. In the manner previously described relay 528 operatesand locks upon the operation of relay 523, advancing sequence switch 500 into position 11 thereby including relay 529 in the fundamental circuit. Counting relays of the spill sender and of thesender 103 are thereupon operated and locked in the "manner previously described until the sender 103 is satisfied as to its final units registration when relay 113 operates opening the fundamental circuit at the sender 103. Thereupon relays 112, 523 and 529 deenergize, relay 523 unlocking relay 528 which in turn deenergizes, advancing sequence switch 500 into position 12. Since it has been assumed that the units digit of the wanted line is three and the line therefore terminates in the fourth set of terminals of the ninth tens group, the No. 9,, No. 9, No. 8, No. 8, No. 7, No. 7, No. 6 and No.6 count-ing relavs will have been operated. 7

Prior to the advance of sequence'switch 500 out of position 11 a circuit will be effective from battery on'conductor 701,-thr0ugh both windings of relay 744, conductor 745, the right contact of cam 611, the back contact of the No. 4 counting relay to ground at the lower contact of cam 606. Until the No. 9 counting relay operates a shunt exists around the right winding of relay 744, extending from the junction between its windings, the left back contact of relay 744, conductor 746, the upper left contact of cam '614,'the lower right contact of cam 608, the back contact of the No. 9 counting relay to ground at the lower contact of cam 606. As soon as the No.

9 counting relay operates this shunt is opened and relay 744 energizes. A circuit is also closed from battery on conductor 701, through both windings of relay 747, conductor 748,

the right contact of cam 613, the back con-' tact of the No. 3 counting relay to ground at the lower contact of cam 606. Until the No. 8 counting relay operatesa shunt exists around the right winding of relay 747, extending 7 from the junction between its windings, over its lnner left back contact, conductor .749, the lower right contact of can] 615, the lower left contact of cam 610, the back contact of the relay 750, conductor 751, the right contact of cam 616, the back contact of the No. 2 counting relay to ground at the lower contact of cam 606. Until the No. 7 counting relay left contact of cam 617, the lower left contact of contact 607, the back contact of the No. 7

counting relay to ground at the lower con- '11:; operates a shunt exists around the right windtact of cam 606. As soon as the No. 7 counting relay operates this shunt is opened and relay- 7 50 operates. A circuit may also be traced from battery on conductor 7 01, through both windings'of relay 753, conductor 754, the

right contact of cam 618, the backfcontact of the No. 1 counting relay toground at the lower contacts of cam 606. Until the No. 6

counting relay operates a' shunt exists around the right winding of relay 753, extending from the junction of the windings thereof, over its inner left back contact, conductor 755, the lower right contact of cam 619, the lower left contact of cam 609, the back contact of the No. 6 counting relay to ground at the lower contact of cam 606. As soon as the No. 6 counting relay operates this shunt is opened and relay 7 energizes. Still another circuit may be traced from battery on conductor 701, over both windings of relay 756, conductor 757, the lower contact of cam 620, the back contact of the No. 0 counting relay to ground at the lowercontact of cam 606. Until the No. 5 counting relay operates the right winding of relay 7 56 is shunted in a circuit extending from the junction between the windings thereof, over its inner left back contact, conductor 758, the upper right contact of cam 621, the lower right contact of cam 612, the back contact of the No. 5 counting relay to ground at the lower contact-of cam 606. Since it has been assumed that the No. 5 counting relay is not energized this shunt is not opened, and relay 756 does not energize. V] hen therefore sequence switch 500 advances out of position 11 into position 12 only register relays 744, 747, 750, and 753 of the final units register remain operated. These relays then look as soon as sequence switch 500 reaches position 11 from battery onronductor 701, over both windings of these relays, the inner right front contact of each, conductor 759 to ground at the upper left contact of cam 603. Upon leaving position 11 the locking circuits of alloperated counting relays are opened at the lower contact of cam 606 and these relays deenergize. I

/Vith sequence switch 500 in position 12 the fundamental circuit through the windings of relays 523 and 112 is again closed but the winding of relay 523 is at this time connected over the left contacts of cam 52 to conductor 521, thence to the ring conductor 202 of the trunk and ground is connected over the upper left contact of cam 527, the right back contact of relay 526, the lower left and upper right contacts of cam 525, to tip conductor 201 of the trunk. This reversal of current advances the sender in the well known manner for making talking selection at the district talking position a circuit is established from battery through resistance 534, the right winding of relay 533, conductor 622', the upper contacts of cam 615, conductor 623, the left contacts of cam 535, brush 521 of trunk finder 520, conductor 217, trunk conductor 201, tip brushes of office selector 150 and district selector 102, the upper contacts of cam 115, the upper right winding of repeating coil 117, the winding of relay 118, the lower right winding of'repeating coil 117 the lower contacts of cam 116, the ring brushes of selectors 102 and 150, trunk conductor 202, conductor 218, brush 524 of trunk finder 520, the left contacts of cam 536, conductor 624, the lower contacts of cam 614, conductor 625 to ground through the left winding of relay 533. Relay 533 energizes in this circuit but relay 118 being polarized does not. Relay 533 upon energizing closes a circuit from ground on its front contact over conductor 626, the right contacts of cam 617, conductor 627, to battery through the winding of relay 537. Relay 537 energizes closing at its left front contact a locking circuit for itself extending to ground at the front contact of relay 533 and over conductor 626 to ground at the lower contacts of cam 621. At its right front contact relay 537 closes an obvious operating circuit for relay 538 which uponenergizing closes a circuit extending from ground over its outer right front contact, the upper contact of cam 539 to battery through the winding of sequence switch magnet 500 advancing this sequence switch out of position 14 into position 18. 1

Incoming brush selection Upon reaching position 15 a circuit is closed from ground at the upper right contact of cam 527 over the lower left contact of cam 540 to battery through the winding of magnet 550 advancing sequence switch 550 into position 4. With sequence switch 200 in position 2 a fundamental switch controlling circuit may be traced from the incoming selector of Fig. 2 to the spill sender, extending from battery through the right winding of relay 207, the lower contacts of cam 219, conductor 221, brush 541 of the trunk finder, the left contact of cam 542, the lower contacts of cam 525, the right back contact of relay 526, the winding of relay 529, the outer right back contact of relay 543, the contacts of cam 544, conductor 628, the back contact of the No. 0 counting relay, conductor 629, the contacts of 0am 545, the right winding of polarized overflow relay 546, resistance 547, brush 549, conductor 222, to ground at the lower contact of cam 220. Relays 207 and 529 energize in this circuit but relay 546 being polarized does not operate.

Relay 207 upon energizing closes a circuit for advancing sequence switch 200 into position 3 extending from battery through the magnet winding of sequence switch 200, the

upper right contact of cam 216 to ground at the left front contact of relay 207. Relay 207 also closes a lockingcircuit for itself extending from battery through its right Winding, the left contact of cam 223, the right frontcontact of relay 207, the left contacts 1 of cam 219 to conductor 221 of the funda mental circuit for holding itself energized over the fundamental circuit after sequence switch 200 leaves position 2. With sequence switch 200' in position 3, a circuit is established for the up-drive magnet 22% extendover the right front contact of relay 207 and the left contacts of cam 219. Relay 207 is held energized over'this circuitbut the'sender ste ping relay deenergizes. V

' it will be recalled that relays 700 and 705 of theincoming hrush register of the spill senderhave' been operated and therefore upon the initial energization of stepping relay 529' over the fundamental circuit 'just traced a circuit is established from ground at the left contact of cam 548, the contact of relay 529,

' conductor630, the upper left contact of cam 631, conduct-or 632', the left back contact of relay 710, the outer right front contact of relay 700, the outer left front contact of relayj 7 05, conductor 760, the back contact of the No. 1 counting relay, the winding of the No. Icounting relay to battery at the left contact of cam 600; The No. 1 counting relay energizes in this circuit looking through the winding of the No. 1 counting relay through the right front contact ofthe No. 1 counting .5 relay over the lower contacts of cam 605 to "'50 round at the lower contact of cam 606; The il'o'. 1 counting relay being shunted at this time over the front contact of the stepping relay 529 does not operate. 'When, however, the stepping relay 529 deenergizes at the time Q the incoming selector reaches its first brush tripping position, theNo. 1' counting relay energizes and extends conductor 7 60 over its front contact, the contacts of cam 633, the winding of'the No. countingrelay to battery at the left contact of cam 600. r 4

As the switch shaft of the incoming selector 250 advances, the brush 226 engages the next insulating segment of commutator strip 227. and the shunt about stepping relay 529 is removed and relay 529 again energizes completing the circuit of the No. 0 counting relay. This counting relay now looks through the winding of the No. 0 counting relay and the winding of relay 634 in parallel over the front contact of the No. 0 counting relay to ground at the lower contact of cam 606. Relay 634 and the No. 0' counting relay do not energize in this circuit until the switch shaft of the incoming selector approaches the next brush selection position when the shunt previously traced is closed permitting stepping relay 529 to'again deenergize. As soon as relay 634 energizes a circuit is closed from its front contact over the upper right contact of cam 540 through the magnet winding of sequence switch 550 advancing such sequence switch into osition 5. In position 5 a circuit is closed through magnet 550,, the upper left contact of cam 540, the left back contact of relay 526, to ground at the inner right front contact of relay 538 for advancing sequence switch 550 into position 6. The; No. 0 counting relay upon energizing opens the fundamental circuit at its back contact thereby7 releasing stepping relay 529 and relay out of position 4 the locking circuits of. the. operated counting relays are opened at the lower contacts of cam 605.

Incoming group selection At the incoming selector relay 207 is held energized over the circuit previously traced to ground over the brush 226 until the switch shaft has been positioned to enable the second set of brushes to be tripped, when the brush 226 will engage an insulating-segment of commutator strip 227. Relay 207 upon deenergizing opens the circuit of the up-drive magnet 224 and closes a circuit extending from battery through thewinding of sequence switch magnet 200, the upper left contact of cam 216, to ground at the left back contact of relay 207 for advancing sequence switch 200 out of position 3 into position 41.v In position 4 a circuit is closed for the trip mag- As the sequence switch 550 advances" net 228 extending from battery through magnet 228 to ground at the right contact of cam 229 Also in posit-ion 4 the fundamental circuit previously traced in again closed'and relays 207 and529 energize thereoven. Relay 207 upon energizing again closes the previously traced circuit for advancing sequence switch 200 out of position 4 intoposition 5, locking itself to the fundamental circuit in the manner previously described. With sequence switch 200 imposition 5 the circuit of the up-drive magnet 224 is again closed over the front contact ofrelay 207 for advancing the switch shaft in its group selection movement. I

During the initial portion of the group selection movement of the switch shaft the sec,- ond set of brushes is tripped in the well- 2 known manner. As the switch shaft approaches its first group selection position the brush 230 engages the first conducting segment of commutator strip 231 closing a circuit for relay 207 extending from ground at the left contact of earn 229, brush 230, commutator strip 231, the upper contact of cam 223 to battery through the right winding of relay 207. This circuit being in shunt of the sender stepping relay 529, the latter relay deenergizes.

At the sender upon the reestablishment of the fundamental circuit for controlling incoming group selection relay 529 energizes and since it has been assumed that no incoming group register relays are at the time en- A right back contact of relay 711, the right back contact of relay 715, conductor 761, the back contact of the No. 3 counting relay to battery through the winding of the No. 3 counting relay and the left contact of cam 600. The No. 3 counting relay energizes and looks through the winding of the No. 3' counting relay and its own front contact to ground at the lower contact of cam 606, but the No. 3 counting relay being shunted does not energize until the stepping relay 529 deenergizes as above described. As the switch shaft of the incoming selector advances the shunt about relay 529'is intermittently established and broken until the counting relays including No. 0 and No. 0 relays and relay 634 become energized in the manner previously described. At that time the brush shaft of the incoming selector will have been positioned at the bottom of the fourth or upper brush group accessible to the tripped 'set of brushes.

Upon the energization of relay 634 the sequence switch 550 is again advanced out of position 6 into position 8 over the circuits previously traced, unlocking the operated 4 counting relays, and the fundamental circuit is opened at the back contact of the 17o. 0 counting relay. As soon after the opening of the fundamental circuit as the commutator brush 230 engages an insulating portion of strip 231 relay 207 releases opening the circuit of the up-drive magnet 224 and advancing sequence switch 200 into position 6. In position 6 a circuit is established from ground at the upper contact of earn 214 to battery through the left winding of relay 207, whereupon relay 207 energizes. At its left front contact relay 207 closes the previously traced circuit for advancing sequence switch 200 into position 7.

As the sequence switch leaves position 6 the energizing circuit of relay 207 is opened at earn 214, but relay 207 remains locked up over its right winding, the left contact of cam 223, the right front contact of relay 207, the upper contacts of cam 232, sleeve brush 233 to ground on the sleeve terminal of the first trunk of the selected group, if the trunk upon which the brushes 233, 235, and 236 are standing is busy. In that event, relay 207 establishes a circuit over the right contact of cam 225, to battery through the winding of up-drive magnet 224. The switch shaft is thereupon advanced in a trunk hunting movement until the brushes are positioned on the terminals of an idle trunk when the holding circuit for relay 207 over the test brush 233 will be opened. Until the brush set is so centered on the idle trunk terminals, relay 207 is held energized over its left winding, the lower contacts of earn 237, commutator strip 238, brush 239, to ground over the lower left contact of cam 225 and the left front contact of relay 207. When the brushes are properly centered relay 207 deenergizes opening the circuit of the updrive magnet 224 and advancing sequence switch 200 into position 8.

Until the sequence switch 200 reaches position 8 ground is placed on the sleeve terminal of the selected trunk over brush 233, the upper contacts of cam 232, the right back contact of relay 207, the upper right and lower left contacts of earn 240 to ground. As soon as sequence switch 200 reaches position 7% direct ground is connected to brush 233 over the right contacts of cam 232. In position 8 a circuit is established from battery through the right winding of relay 207, the lower, right and upper left contacts ofcam 219 to ground over the upper left and lower right contacts of cam 232. Relay 207 energizes and closes the previously traced circuit for advancing sequence switch 200 into the'selection beyond position 9. After the sequence switch 200 leaves position 8, relay 207 remains energized over a holding circuit eX- tending from battery through its right winding, the left contact of cam 223, right front contact of relay 207, the upper contact of cam 242, brush 236, conductor 306, the upper left and lower right contacts of cam 307 to ground at the lower left contact of cam 338.

Finalbrush selection lower left contact of cam 304, conductor 305,

brush 235, lower left contact of cam 241, thence as previously traced over conductor 221, through the winding of sender stepping relay 529, returning over conductor 222 to ground at the lower contact of cam 220. Re-

lays 302 and 529 energize in this circuit. Relay 302 upon energizing locks in a circuit from battery over the upper contact of cam 301, its right winding, the upper contact of cam 308, the inner left front contact of relay 302,

theupper left contact of cam 303, thence over the fundamental circuit, and closes a circuit extending from battery through the left winding of relay 310, the left contact of cam 311, the outer left front'contact of relay 302 to ground at the lower left contact of cam 312. Relay 310 energizes and looks through its left winding, the back contact of relay 313, the left front contact of relay 310, to ground on sleeve conductor 234 and at its right front contact establishes a circuit from ground over the lower contacts of cam 309 to battery through. the magnet winding of sequenceswitch 300' for advancing the sequence switch into position 2. With sequence switch 300 in position2 and relay 302 energized a circuit is closed for the high speed up-drive magnet 314 which may be traced from battery through the magnet 314, the upper contact of cam 315,.the outer left front contact of relay 302 to ground at the lower left contact of cam 312. Magnet 314 upon energizing causes the switch shaft to be moved upwardly in its brush selection movement. During the upward movement of the switch shaft an intermittent ground is connected to thefundamental circuit for intermittently shunting the: stepping relay 529 of the sender over a circuit which may be traced from trunk conductor 305, the lower left and upper right contactsof cam 304, commutator strip 316,

brush 317, to ground at the lower right contact of cam 338. "On the initial closure of the fundamental circuit relay 529 energizes and since it has been assumed that relay 724 of thefinal brush register of the sender is at the time energizeda circuit is established from ground at the left contact of cam 548 contact of relay 529, conductor 630, the lower left contact of cam 631, conductor 636, the left front contact of-relay 7 24, conductor 762, the back contact of the No. 4 counting relay to battery through the winding of the No. 4

countingrelay and the left contact of cam 600. The No. 4 counting relay looks over a V circuit through the winding of the No. 4

counting-relay and its own front contact in the manner previously described, the No. 4

' counting relay operating in this locking circuitpupon the first deenergization of relay 529.. In response to the intermittent shunt viously traced through the windingsof relays 302 and 529. Until the selector switch shaft reaches a position in which the fourth brush set may be tripped, relay 302 is held. energized over the previously traced shunt path ex tending to ground over the commutator brush 317. Relay 302 thereupon deenergizes opening the circuit of the up-drive magnet 314 and at its outer left back contact closes acircuit extending from battery through the winding of sequence switch magnet 300, the

left contact of cam 318, the outer left back contact of relay 302 to ground at the: lower left contact of cam 312 for advancing sequence switch 300 into position 3. In posi tion 3 a circuit is established for the trip magnet 319 over the upper right contact of cam established. 'Relay 302 also establishes the previously traced locking circuit for itself" extending through its inner left front contact for maintaining itself energized over the fundamental circuit after sequence switch 300 leaves position 3. Upon the energization of the high speed up-drive magnet 314, the switch shaft isdriven upwardly in its group or tens selecting movement and during the intial portion of this movement the fifth set of brushes is tripped. During the remainder of the group selecting movement the tripped set f brushes travels upwardly in contact with the terminals of the bank with which it is associated. During this movement an intermittent ground is connected to the fundamental circuit in shunt of the sender stepping relay 529, from conductor'305 over the lower left contact of cam 304, upper right contact of cam 303, commutator strip 320,

brush 321 to ground at the lower right contact of cam 338. Relay 302 is held energized over this shunt path. 7

The stepping relay 529 of the sender upon energizing over the fundamental circuit, with sequence switch 550 in position 10, clo'ses a circuit for the Not 8-counting relay extend? ing from ground at the left contact of cam 548 through the contact of relay 529, conductor 630, the lower right contact of cam 631, conduct-or 637, the right back contact of register relay 728, the outer right front contact of relay 7 40, the outer right back contact of relay 739, conductor 763, the back contact of the N o. 8' counting relay, the wind ing of the N o. 8 counting relay to battery at the left contact of cam 600. 'In the man

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