US1815169A - Multioffice telephone system - Google Patents

Description

Jul 21, 1931. R. F. STEHLIK MULTIOFFICE TELEPHONE SYSTEM Original Fild March 14, 1927 4 Sheets-Shee't l hm??? feudal/3h F ETEhlik R. F. STEHLIK Rudolph F. STEhh'k July 21, 1931.

MULTIOFFICE TELEPHONE SYSTEM July 21, .1931. R. FysTEHLlK MULTIOFFICE TELEPHONE SYSTEM Originl Filed Mai-ch 14.

1927 4 Sheets-Sheet s Inusfi Eudnl h R. F; STEHLIK 1,815,169

4 Sheets-She et Av 1:1 1 w k I I MULTIOFFICE TELEPHONE SYSTEM Original Filed March 14, 1927 Jul 21, 1931.

lmren ur' FuduZphFE'lEhlik Patented July 21, 1931 STATES RUDOLPH F. STEI-ILIK, OF CHICAGO, ILLINOIB, ASSIGNGR TO RESERVE HOLDING COM- PAHY, GF CI-IECAGG, 11111131013, .91 CC-RPCRATION OF DELAWARE IVEULTIOFFICE TELEPHONE SYSTEM Original application filed March 14, 1927, Serial No. 175,187. Divided and this application filed December 31, 1958, Serial No. 329,493.

This invention relates in general to multioflice telephone systems but more particularly to such systems as comprise in one network ofiices or exchanges of two different kinds, the oflices of one kind being manual oilices wherein connections are completed by means of automatic switches, and the object of the invention is to provide new and improved cir cuit arrangements for handling interofiice calls between the automatic and manual exchanges.

Systems having both kinds of exchanges as above pointed outare becoming quite common and may arise either by consolidation of existing manual and automatic systems, serving the same territory, or by the process of changing over a manual system to an auto matic system. Usually in the latter case only one office at a time is converted from manual to automatic and it follows that during the period of transition there will necessarily be both kinds of offices in operation. However the above situation may arise, it is necessary to provide suitable circuit arrangements for handling calls from the manual offices to the automatic oflices, and from the automatic offices to the manual o'llices. The present invention is concerned only with the latter class of calls, and provides certain improvements in systems comprising automatic to manual trunks which are accessible to selector switches in the automatic othces and terminate in plugs in front of a B operator at the manual office, together with call registers for registering the digits in telephone numbers called by automatic subscribers when the trunks are taken for use, and an indicating device upon which such numbers are shown to the operator one after the other as fast as she can complete the desired connections.

This application is a division of my copending application Serial No. 175,187, filed March 14, 1.927, on which United States Patent No. 1,775,83 was granted Sept. 16, 1930.

The main feature of the invention in this divisional application relates to the special method of multipling switches at an intermediate distributing frame.

. In the drawings, comprising Figs. 1, 2, 8,

Renewed July 14, 19130.

and 1', there is shown by means of the usual circuit diagrams the apparatus and circuit connections thereof which is involved in a complete connection extending from the automatic substation A, Fig. 1, to a manual substation A, Fig. 2.

The apparatus indicatedin Fig. 1, is located in an automatic exchange, while the apparatus indicated in Figs. 2, 3, and 4, is located in a manual exchange. Inasmuch as the automatic switching equipment itself and the manual equipment are both well known and of the usual type, no detailed description of the mechanical features of this apparatus will be given, except insofar as it is found convenient or necessary to do so in the explanation of the operations of the circuits.

Referring to Fig. 1, the substation A is one of a plurality of ordinary automatic substations terminating in the automatic exchange previously referred to, and is provided with the usual talking equipment and ringer, and also with a calling device of a well known type which is indicated by the reference character S, through the medium of which the subscriber controls the central office switches.

The line conductors 11 and 12 extend to the exchange where they terminate in the line switch C, which may be briefly described as a rotary line switch whose moveable terminals or wipers have no normal position, and which have movements in a forword direction only. The construction of a line switch of this type is well known in the art, and its function, also well understood, is to extend its associated line when calling to an idle trunk line. In carrying out this object, a plurality of these individual line switches are given access to a group of trunk lines extending to first selector switches. One of the trunk lines to which the line switch C has access is shown in the drawings as extending to the first selector D, which is a vertical and rotary selector of the well known Strowger type. In a multi-oflice system of the kind herein contemplated the first selector switches are usually known as o-flice selectors and the selector D in common with a plurality of similar selectors has access. to a plurality and its resting contact, upper left hand winding of the repeating coil of the cord circuit O, normally closed springs controlled by armature 237, and upper Winding of the line relay 206 to battery. Upon energizing, line relay 206 causes the energization of the release relay 205. The latter relay upon energizing connects ground at armature 235 to the lower winding of the line relay 206 so that the line relay may be maintained energized by a bridge at the repeater E.

Referring now to the repeater E, the relay 104 is energized from ground at armature 114 but is slow to pull up so as to allow time for operating the line relay at the cord circuit 0 over the upper talking conductor as explained. On energizing, relay 104 disconnects ground from the conductor 130 and the initial energizing circuit of the line relay 206 of the cord circuit 0. At armature 120 and its working contact, relay 104 connects ground to the release trunk conductor 77; at armature 121 and its working contact closes a circuit through the polarizing winding of the electropolarized relay 105; and at armature 118 and its working contact completes a bridge across the trunk conductors 130 and 131 which may be traced over the following path: conductor 130, armature 113 and its working contact, working contacts of armature 118 and said armature, armature 116 and its resting contact, lower winding of the electro-polarized relay 105, normally closed springs controlled by armature 108 of relay 100, right hand winding 01'' the impedance coil 106, and working contact of armature 111 and said armature to conductor 131. By the closure of this bridge across the trunk line a circuit is completed for maintaining energized the double wound line relay 206 of the cord circuit O.

hen the line and release relays of cord circuit 0 are operated, as above explained, the latter relay at armature 232 opens a point in the circuit of the supervisory lamp SL and at its working contact connects ground to conductor 257. At armature 233, relay 205 prepares a point in the impulsing circuit; at armature 235 and its working contact connects ground to the lower winding of the line relay 206 as previously explained.

It may well be mentioned at this point that the register selector C is a preselecting switch, and it is assumed that the switch C has preselected the register set shown in the drawings in Fig. 3. The method of preselecting an idle register set will be fully described hereinafter. Vhen relay 205 pulls up it closes at armature 234 an energizing circuit for relay 204 as follows: from ground by way of armature 224 and its resting contact, lower winding of relay 204, working contact of armature 234 and said armature, armature 222 and its resting contact, resting contact of armature 218 and said armature, conductor 301, wiper 301, bank contact connected to terminal pin 305, jumper 308, terminal contact 311, conductor 372, armature 331 and its resting contact, terminal 379, jumper 380, terminal 381, armature 334 and its resting contact, and winding of relay 325 to battery.

When the above traced circui; for relay 325 is closed, said relay energizes and at armature 338 and its resting contact opens a normally closed short circuit from around the relay armature 339 and its working contact closes a circuit for operating the time switch P, and at armature 340 and its resting contact opens one of the several energizing circuits for the relay 392.

Returning now to the cord circuit 0, relay 204 is energized over the previously traced circuit and at armature 227 and its working contact prepares a point in the circuit for the call lamp CL, at armature 228 and its working contact prepares a circuit for relay 201, at armature 230 and its working contact closes a locking circuit for itself through armatures 220 and 217 to grounded conductor 257, and at armature 231 and its working contact connects direct ground to the release trunk conductor 301 to guard the seized register set from being seized by other register selectors such as C. At armature 229 and its restin contact, relay 204 opens a point in the circuit for the busy relay 202, so that when impulsing is started the busy relay will not be energized from ground at armature 236, and at its working contact prepares the impulsing circuit extending over conductor 303 to the register set. 7

Everything is now in readiness for the transmission of the second series of impulses. The subscriber will now operate his calling device in accordance with the digit 3, which will cause line relay 101 of the repeater E to fall back a corresponding number of times, which results in the operation of slow relay 103 for placing a direct bridge across the trunk conductors 130 and 131. The operation of line relay 101 causes the circuit of the line relay 206 to be interrupted a like number of times. Each time line relay 206 falls back an impulse is transmitted to stepping magnet 461 over the following circuit: ground, armature 236 and its resting contact, working contact of armature 233 and said armature, armature 229 and its working contact, impulse conductor 303, wiper 303, Fig. 3. bank contact engaged by wiper 303, terminal pin 306, jumper 309, terminal contact 312,conductor 371, winding of relay 327, wiper- 355 of the register controlled switch RCS, conductor 360, stepping magnet 461 of the register switch R1 to battery. By the operation of the stepping magnet 461 wiper 464 of the register switch R1 is advanced three steps and is brought to rest in engagement with the third contact of its bank. The slow acting relay 327 is energized in series [His with stepping magnet 461 -and retains its armature 344 attracted while the said magnet is being operated. In operated position, relay 327 closes, a circuit for the slow acting relay 328, which is held in operated position also during the operation of the first register switch. After the last impulse has been transmitted, the slow-acting relay 327 will deenergize and break the circuit of relay 328 at armature 344. Since the latter relay is slowa-cting, however, a circuit will be closed for an instant which extends from the grounded armature 344 by way of its resting contact, working contact of armature 345 and said armature, and the winding of stepping magnet 359 of the register control switch BCS to battery. One impulse is thus transmitted to the stepping magnet 359, and the wipers 355 and 356 are advanced one step into engagement with the second contacts in their respective banks. The advance of wiper 356 is of no eii'ect, but when wiper 355 moves from its first contact to the second, the operating C11- cuit is thus transferred to conductor 361 which extends to the stepping magnet 441 of the register switch R2.

It may well be mentioned at this time that relay 32 3 was energized as soon as the register switch R moved oft-normal. The circuit for relay 323 may be traced as follows from ground through low resistance windlng of relay 322, winding of high resistance relay 323, conductor 405, off-normal springs 463, winding of release magnet 462, to battery. The relay 322 and release magnet 462 are not energized in this circuit on account of tee high resistance of relay 323. At armature 364, relay 323 removes ground from conductor 37 6 and prepares a circuit for relay 324 at its working contact. Relay 324 how ever does not energize at this time on account of the ground connection at armature 231, Fig. 2, extending over conduct-or 301.

The calling subscriber will now operate his calling device in accordance with the next digit in the desired number. As a result, the line relay 206 in the cord c1rcu1t operates the same as before, but now sends four impulses over the operating circuit to the stepping magnet 441 of the register switch R2. The stepping magnet 441 is thus operated to advance its wipers 444 four steps and the wiper is brought to rest in engagement with the fourth contact in its banks.

The slow acting relays 327 and are energized during the transmission of the second series of impulses the as durn tne first, and when the impulses cease another impulse of current is transmitted to the stepping magnet 359 or" the register control switch RCS, thus advancing the wipers and 356 another step, and transferring the operating circuit by way of conductor 362 to the stepping magnet 421 of the register switch R3.

It will not be necessary to consider in (13-. tail the manner in which the register switches R3 and R4 are operated. lVhen the digit 5 is called a series of five impulses are transmitted to the stepping magnet 421 of the register switch R3 and the wiper 424 is advanced into engagement with the fifth con-v tact in its bank. At the end of the series of impulses, the register controlled switch is op-- erated one step and the operating circuit is transferred by way oi conductor 000 to the stepping magnet 401 of the register switch R4. The series of six impulses which results from the calling of the final digit thus causes the operation of tne stepping magnet 401 and the wiper 404 is advanced into engagement with the sixth contact in its bank. The stepping magnet 359 of the register control switch is given another impulse of current also at the end of the last series of impulses and wipers 355 and 356 are advanced one more step.

By the last operation or the register control switch RC5 wiper 356 is brought into engagement with the fifth contact in its bank and ground is placed on conductor'369, resulting in the energization of relay 326. Upon attracting its armature 342, relay 326 steps the operation of the timing switch P, while at armature 341 ground is connected by way of armature 330 for lighting the setup lamp 370 thereby indicating to an operator that a call has been set up on the third register set. Relay 326 at armature 343 and its resting Contact removes a short circuit from around the relay 329 and at its work ing contact closes a circuit over the conductor 377 for energizing the relay 231 of the switch CCS in Fig. 2. Armature 343 also removes ground from conductor 376 thereby removing ground from the bank contact in the switch CCS which corresponds to the reg ister set shown in Fig. 3.

The consecution switch CCS has all its bank contacts normally grounded over conductors such as conductor 376 and as soon as relays such as relays 326 and 323 are energized ground is removed from the bank contact corresponding to the register set in use.

Responsive to the energization of relay 281 over the above traced circuit, said relay at armature 282 and its working contact closes a circuit for operating the stepping magnet 283 by way of the grounded bank contacts of the consecution switch CCS. The stepping magnet 2S3 energizes from ground on the grounded bank contacts encountered by wiper 280, interrupts its own circuit, and continues to operate in a buzzerlike manner until the wiper 230 encounters the bank contact connected to conductor 376 from which ground has been previously removed. Responsive to the wiper 280 coming into engagement with the bank contact connected to conductor 376, a circuit is no longer closed for inn the stepping magnet and acircuit may now be traced for energizing the high resistance relay 329 Fig. 3, as follows: from ground winding of relay 329, armature and its resting contact, conductor 378, conductor 376, bank contact individual to the register set shown in Fig. 3, wiper 230, working contact of armature 282 and said armature, interrupter springs of the stepping magnet 233, and winding of stepping magnet 283 to battery. Due to the high resistance of relay 329 the stepping magnet 283 is not energized over the above traced circuit. Relay 329, however, is energized and at armature 353 connects ground to conductor 373 for lighting the call lamp CL over a circuit as follows: from ground, working contact of armature 353 and said armature, conductor 373, terminal 3 3, jumper 310, terminal 307, bank contact of the register selector C, wiper 304, conductor 304, armature 227 and its working contact,

Winding of relay 211, resting contact of ar mature 219 and said armature, armature and its resting contact, call lamp CL to bat tery. Relay 211 is energized over the above traced circuit and at armature 24S disconnects the supervisory lamp SL. Other calls may be registered on the other register sets at any time now and when the registration is completed the set-up-pilot lamps, such as lamp 370, corresponding to the register sets in use will be lighted, but this has no effect on the consecution switch CCS, which makes no further movement until the call on the third register set has been disposed of.

Relay 329 is the relay which switches over the registered call to the lamps of the indicating device and the manner in which this is done will now be pointed out, it being recollected that the wipers 464, 444, 424 and 404, are now resting on the 3rd, 4th, 5th, and (3th contacts in their respective banks. When the armatures 348 of relay 329 are operated, ground is connected to conductors 349 to 352, inclusive. the conductors 349 to 352, inclusive, grounded the conductors 476, 455, 343, and 413 will also'be grounded. These latter mentioned conductors extend to the indicating device V and terminate in the #3 lamp of the first group, the #4 lamp of the second group, the #5 lamp at the third group, and the #6 lamp in the fourth group, respectively. The other side of the lamp is connected to battery and the lamps mentioned are accordingly illuminated.

The manner in which the operator handles the call thus displayed before her will now he considered. When the relay 3.29 in Fig. 3 pulls up and closes the circuit for displaying the registered number to the operator, it also closes at'its armature 353 the circuit for the call lamp CL in the cord circuit 0. The lighting of the lamp CL which is individual to the cord circuit O-is lighted simultaneously It follows, therefore, that with with the lamps in the indicating device V,

thus enabling the operator to know which one of the cord circuits is being used by the automatic subscrioer, whose wanted number is at this particular time being shown on the indicating device; Having observed the #3456 and knowing by the lighting of the called lamp CL that the cord circuit 0 is the one in use, the operator will test the multiple jack of the line with the tip of her plug in the usual manner in order to find. out whether or not the-line is busy. If the line is found tohe in use, the operator will hear the well known busyclick, and will imme. diately operate her busy key BK. The two keys indicated by BK are in reality one key and have been shown as two keys so as to simplify the drawings. By the operation of the upperbusy key BK the stepping magnet 283 of the consecution control switch CCC is energized. A circuit is also closed through the lower busy rey BK from ground at said key, through worring contact of armature 242 of relay 209 which was previously energized in parallel with relay 211, armature 243 and its resting contact, winding of relay 202 0 battery. Relay 202 at armature 220 opens l e locking circuit of relay 204 which there-. upon deenergizes, at armature 222 removes ground from the release trunk conductor 301, and at armature 223 and its working contact connects the busy tone through the condenser 259, through the lower right hand winding of relay 208 to battery. The busy tone is now transmitted to the calling subscriber in the well known manner and need not be explained in detail. I

By the removal of ground from the release trunk conductor 301, the short circuit around relay 324 has been removed, and said relay energizes over a circuit from ground at armature 364 in series with relay 325. Relay 324 upon energizing closes at armature 336 and its working contact a circuit for releasing the register control switch, the time switch T, and all of the register switches R1 to R4 inclusive, as follows ground through the low resistance winding of relay 322, armature 336 and its workin contact, off normal springs 357 of the register control switch l-ZCS, release magnet 358 to battery; to the resting contact of arn'iature 347 and said ar mature, elf normal springs 337 of the time switch P, release magnet 366 to battery; to conductor 405 from which point ground is connected to tie release magnets 402, 422, and 462 through oil- normal contacts 403, 423, 443 and 463, respectively. The register control switch RC8, the time switch P, and the register switches R1 to R4. inclusive,

release in the well known manner. Relay 322 is enei zed in series with the various release magnets and at armature 334 and its working contact connects ground to the conductor 372 thereby rendering the register set busy until the apparatus in the set has been completely restored to normal. lVhen relay 324 operates its armature 336, relay 323 is short circuited and after an interval, said relay deenergizes. Relay 323 upon deenergizmg opens at armature 364 the circuit of re lays 324 and 325 which thereupon deenergize. At armature 364 and its resting contact, relay 323 connects ground to conductor 376 so as to busy the register set in the consecution control switch. Relay 325 deenergizes before relay 324 thereby maintaining at armature 338 the short circuit around relay 323. As soon as all of the register switches, the register control switch and the time switch P have been returned to normal, the circuitof relay 322 is opened at the various olf normal contacts. In case any one of the above switches did not properly release, relay 322' would be maintained energized, thereby maintaining the register set busy. The relay 326 was also deenergized responsive to the release of the register control switch thereby causing relay 281 of the switch COS to deenergize. Relay 329 is again short circuited and said relay releases and disconnects ground from conductors 349 to 352, inclusive. All of the apparatus shown in Figs. 3 and 4, have been returned to their normal positions, and are available for use in another call.

When the operator releases the busy key BK, the stepping magnet 283 of the consecution control switch GCS deenergizes and advances the Wiper 280 one step.

The reason for holding stepping magnet 283 energized during the time the busy key is depressed is to prevent the operation of the switch CGS thereby preventing the operation of busy relays in other cord circuits when calls on the other cord circuits are waiting to be displayed.

Assuming however, that the line is found to be idle, the operator will at once insert the plug Pintothe jack of the wanted line, which in the present case is the jack J. As soon as the plug is inserted into-the jack, a circuit is completed for the sleeve relay 210 in series with the cut-oil relay 261 of the called line, and the latter relay is energized to clear the line of its normal battery and ground connections in the usual manner. Relay 210 is energized also and at armature 240 prepares a circuit for the supervisory lamp SL, at armature 241 opens the circuit of relay 209 at its resting contact and at its working contact closes acircuit for energizing relay 201, at armature 243 and its resting contact opens the circuit of the busy relay 202', at armature 244 and its resting contact opens the circuit or" the call lamp CL, at armature 245 and its working contact connects ground to conductor 279, at armatures 246 and 247 and their'working contacts completes a ring back circuit for transmitting ringing induction to the calling subscriber, at armature 247 and its working contact connects generator to the called line, and at the restl-ng contact of armature 247 disconnects the operators head-set. Ringing current is now connected tothe cal-led subscriber over the P, tip of jack J through the called subscri=bers ringers, back over the ring conductor of plug P, armature 250 and its resting contact, resistance 259, to battery.

l/Vhen the sleeve relay was energized it closed a circuit for energizing relay 201 as follows: grounded conductor 304, armature 227 and its working contact, armature 241 and its working contact, working contact of armature 228- and said armature, normally closed springs controlled by armature 217, and winding oil relay 201 to-ba-ttery. Relay 201, upon energizing, closes alocki-ng' circuit for itself at armature 217 and its working contact and at armature 217 and its restingcontact opens the locking circuit of relay 204. At armature 2118, relay 201 disconnects ground from the release trunk conductor 301', and at armature 21'9prepares a substitute circuit for the call lamp- CL whichincludes the interrupter I for flashing the call lamp CL in case the operator removes the plug P fromthe ack prematurely.

Responsive tothe removal of ground from the conductor 301 the short circuit around relay 324 is removed and said relay energizes in series with relay 32-5. The operation of the relay 322' and the release magnets of the various switches in- Figs. 3 and 4 are now the same as previously described and the apparatus is restored to normal. The register control switch, the register switches, and the consecution control switch are now in readiness to be used for another call.

Referring now tothe cord circuit 0, it has been explained how the connection has been completed to the line of the called station A, and how ringing current is' projected over the called line to signal the subscriber. During the ringing operation a tone is induced in the lower right hand winding of the repeating coil of the cord circuit 0- by means' of which the calling subscriber is advised that the called subscriber is being' sig-' nalled When the called subscriber answers, the ring cut-oil" relay 212 energizes-in a well known manner and closes a circuit at a-rma-- ture 249 for relay 213 from ground over the sleeve of plug P' and jack J. Relay 213, upon energizing, at armature 251 completes a locking circuit foritself and at armatures 250 and 256 and their resting contacts disconnects the generator from the called line and at their working contacts connects the line of the called subscriber to the right hand windings of the repeating coil thereby completing a talking circuit for the called subscriber which includes the lower and upper windings of relay 208 and the right hand windings of the repeating coil. Relay 208 is energized over the called subscribers loop and at armature 239 completes an energizing circuit for the reversing relay 207. In energized position, relay 207 reverses theetrunk conductors 130 and 131 as regards their connections with the windings of the line relay 206, and the direction of current flow in the trunk line is thus reversed. Due to the reversal of current flow in the trunk line the polarized relay in the repeater E is now energized and at armature 119 and its working contact completes a circuit for energizing the reversing relay 100 of the repeater E. Upon energizing relay 100 reverses the trunk conductor 7 6 and 78 as regards their connections with the winding of the line relay 101, and the direction of current flow in the calling line is thus reversed. This operation may be used for operating a meter or for similar purposes, and is provided in accordance with standard practice, although it is of no utility in the particular system shown herein.

The required connection having been established, the subscribers may now converse as desired. When the. conversation is finished both subscribers will hang up their receivers, and the replacement of the receiver at the 'alling station A causes the deenergization of the line relay 101 in the repeater E and also the release of slow acting release relay 102. Relay 101 upon releasing, completes a circuit for relay 103 so that when relay 102 deenergizes, ground is removed from release conductor 77 thereby allowing the automatic switches to be restored to normal in the usual manner. The bridge across the trunk conductors 130 and 131 being broken by the deenergization of line relay 101 of the repeater E the circuit of the line relay 206 in the cord circuit 0 is thereby o ened whereupon said relay deenergizes. fter a short interval of time the slow acting relay 205 also deenergizes and closes a circuit for the supervisory lamp SL at armature 232, and at the same armature also opens the circuit of relays 207 and 201 which thereupon deenergize. Relay 205 also removes ground from conductor 279 and prepares a circuit for relay 203. When the slow-acting relay 102 of the repeater E deenergizes it opens at armature 114 a circuit for relay 104 and at the same armature by way of its resting contact substitutes another circuit for energizing relay 104 as follows: from ground by way of armature 245 and its working contact, conductor 279, lower winding of line relay 206, normally closed springs controlled by armature 238, lower left hand winding of the repeating coil, resting contact of armature 216 and said armature, conductor 131, resting contact of armature 114, and winding of relay 104 to battery. Relay 104 energizes over the above traced circuit but due to its high resistance, the line relay 206 is not energized. At armature 120, relay 104 connects ground to the release conductor 77 thereby 1naintaining-tl1is trunl: circuit busy to the automatic switches in the automatic office as long as the plug P remains inserted in the jack J.

The automatic switches now have been re leased, disconnect signal has been given to the operator, and the trunk line in use has been made busy pending the pulling down of the connection. lVhen the operator observes the lighted supervisory lamp SL she will remove the plug of the cord circuit 0 from the jack and relays 210 and 213 are deenergized and restored to normal. By the falling back of relay 210 the circuit of the supervisory lamp SL is broken at armature 240 and at armature 245 ground is removed from conductor 279 thereby permitting the relay 104 of the repeater E to deenergize and remove ground from the release trunk conductor 77. All the apparatus has now been restored and is ready for use in handling another call.

Certain details of the system will now be explained which it was not convenient to go into before, and the first thing which will be considered is the preselecting operation of the register selector C. For this purpose, it will be assumed that the cord circuit 0 is idle, that the wipers of the register selector switch C are standing in the position shown in the drawing, Fig. 3, and that the register set associated with these bank contacts becomes busy. Under the above conditions circuit can now be traced to the lower winding of the diiterential relay 203 of the cord circuit O over the following path: from ground on the bank contact associated with the busy register set, wiper 301, conductor 301, armature 21S and its resting contact, resting contact of armature 222 and said armature, armature 234 and its resting contact, and lower winding of relay 203 to battery. Relay 203 energizes over the above traced circuit and at armature 225 maintains the above traced circuit independent of armature 234 so that if the cord circuit should be taken into use, the circuit of the relay 203 would not be opened by the operation of the release relay 205. At armature 224 and its resting contact, relay 203 opens the energizing circuit for relay 204 so that relay 204 cannot energize until after an idle register set has been selected. In addition to the above, relay 203 at armature 224 and its working contact connects ground to conductor 302 thereby closing a circuit for the stepping magnet 320 of the register selecter C" so that said stepping magnet will operate in a manner of a buzzer until ground is removed from conductor 302, Although relay Jim contacts of the register selectors.

203 is a difierential relay the resistance in serted in series with the upper winding will not permit the relay to be deenergized when armature 224 connects ground to the upper winding of said relay. As long asthe wiper 301 encounters grounded contacts of busy register sets, relay 203 will be maintained energized through its lower winding- It will now be assumed that an idle register set is reached and when the test wiper 301 engages the bank contact associated therewith, said contact will not be grounded, but will have a battery potential thereon. Under this condition the circuitto the lower winding of relay 203 is opened. Due to the current flow through the upper winding of relay 203, magnetic flux will be built up in opposition to the magnetic flux created by the circuit through the lower winding and when the flux reaches a certain point said relay is quickly deenergized, thereby removing. ground from. conductor 302' and stopping the operation of the register selector on the idle registerset.

Having described the operation of the system as a whole, adetailed description will now be given of the main feature of th s invention which relates to the method of multipling the register sets, which are only eight in number to the register selector banks. The multipling of the register sets in the banks of the register selectors is accomplished by the aid on an int rmediate distributing frame. The banks of all the register selectors at the position are connected in multiple and a cable connects the multiply connected banks with one side of the distributing frame, where the cable is terminated on twenty-five sets of terminal pins.

In the bottom half of Fi 4, the distributing frame is indicated by the reference characters I. D. F. The lower row of twentyfive terminals are the terminals for the release trunk conductors coming from the bank The release. trunk conductors of the eight registe sets are connected to. eight terminal contacts on the other side of the I. D. F. Although only therelease trunk terminals are shown, it will be understood that there are three terminals to each set. As the register selectors have access to only eight register sets the terminal pins are divided into three groups, the first group comprising terminal pins 1 to .8, inclusive, the second group 9 to 16, inclusive, and the third group 17 to 25, inclusive. The eight register sets are cross connected by jumpers atv the I. D, 13., to. the terminal pins numbered 1 to. 25, inclusive. The number 1 register set is multipled to the #1, #13,. and #19 terminal. pins, the num her 2 register set is multipled to the #2, #9, and #22 terminal pins, the number 3 register set is multipled tothe #3,. #14, and #17 terminal pins,,ihe number-.4 register set is multipled to the #4, #10, and #20 terminal pins, the number 5 register set multipled to the #5, #15, and #23 terminal pins, the #6 register set is multipled to the #6, #11, and #18 terminal pins, the number 7 register set is multipled to the #7 and #21 terminal pins, and the number 8 register is multipled to the #12 and #24 terminal pins. The eighth, sixteenth, and twenty-fifth terminal pins are dead and are cross connected in such a manner that they provide stopping positions for the register selectors in case all eight register sets become busy. lVith the register sets multipled at the I. D. F, in the manner pointed out it neces sarily follows that each of the register sets is accessible to a register selector at a plurality of points in its bank. Although the corre sponding bank contacts of all the register selectors at the position are connected in a straight multiple, the cross connections at the l. D. E, divides each bank into a plurality of groups of bank contacts and provides a slip between the bank contacts in each of the groups. Considerable saving is effected by mul ipl-ing the register sets at the I. D. F., because it permits changes such as varying the number of register sets to. be used or for varying the slip in the multiple between bank con tacts to be readily and easily made at the same time keeping the multiples straight between banks.

The slip in the register selector bank contac s between groups is provided for the purpose of preventing all the idle preselecting register selectors from preselecting the same dle register set on their next operation in case hey had previously selected the same regiser set. For example, it will be assumed that here is a register selector in engagement with the multiples 'otthe first register set of the difterent groups that is, a first register selector is in engagement with the #1 bank contact in the first group of its associated bank, a

r v re second register selectoris in engagement with the #13 bank contact in the second group of its associated bank, and a third register selector is in engagement with the #19 bank contact in the third group. of its associated bank. Assuming now that the #1 register set becomes busy, ground is connected to the mul iples of said set causing all of the register selectors which are in engagement therewith to start hunting topreseleet another idle register set. The said first register selector will step one step into engagement with the 2nd bank contact or the multiples-of the #2 register set, the said second register selector will step one step into engagement with the 14th hankcontact or the multiples of the #3 register set, and the said third selector will step one step into engagement with the 20th bank contact or the multiples of the #4 register set. It can be seen from the foregoing that each. register selector, which havetheir wipers positioned in different groups,selects a different register set for each corresponding step when they are initially started from multiples of the same register set.

Having explained in detail how the bank contacts of the register selectors are connected in a slip multiple by means of jumpers at the I. D. R, when eight register sets are to be used, I will now briefly point out how the bank contacts of the register selectors are cross-connected to the register sets at the I. D. F., when a variable number of register sets is to be used at an operators position.

The following is a chart showing the slip multiple arrangement for cross-connecting the bank contacts of the register selectors at the I. D. F., to the register sets Chart Register sel. 8 Reg. 7 Reg. 6 Reg. 5 Reg. bank Contact sets sets sets sets 1 1 2 2 l 1 3 3 2 2 4 4 3 3 5 5 4 4 6 Dead 5 Dead 7 6 Dead 5 #1 dead 7 2 2 2 2 4 4 4 4 6 1 6 6 1 Dead 8 Dead 3 3 1 1 Dead 5 3 3 5 1 5 5 1 4 #2 dead 7 6 Dead 3 3 3 2 6 6 2 5 1 Dead Dead 4 4 1 4 3 7 4 1 Dead 2 7 5 1 5 2 2 5 8 5 6 3 #3 dead Dead 3 2 A Dead Dead Reading from left to right, the lefthand column indicates the numbers of the register selector bank contacts which are connected to correspondingly numbered terminal pins on.

the I. D. E, and the other columns indicate the number of the register sets which are multipled to the selector bank contacts in the following manner. In order to explain the chart it will be assumed that only six register sets are to be used at an operators position and therefore only the first and fourth columns may be considered. The #1 bank contact is multipled to the #1 register, the #2 bank contact to the #2 register set, the #3 bank contact to the #3 register set, the #4 bank contact to #4 register set, the #5 bank contact to the #5 register set, and the #6 bank contact is connected to a dead terminal pin. In the next group of bank contacts the #7 bank contact is multipled to the #2 register set, the #8 bank contact to the #4; register set, the #9 bank contact to the #6 register set, etc. In case 5 or 7 register sets were to be used at an operators position, the register sets would be cross-connected at the I. D. F., in an obvious manner. It can plainly be seen from the foregoing that in order to change the number of register sets to be used or in order to change the slip multiple it is only necessary to change the cross connections or jumpers at the I. D. F.

It can plainly be seen that this method of multipling is not necessarily limited to the register sets shown in the drawings and is readily adaptable for use with other switches.

There are provided in the instant case eight register sets per operators position, seven of which are normally available for use while the eighth is artificially made busy. hen all seven register sets become busy, a circuit will be completed forenergizing the all trunk busy relay ATB to busy the operators position. A still further feature of the invention which may be described in conjunction with the preceding, relates to the means for rendering the eighth register set idle so that if a call should come into the operators position before said position has been made busy, the call would seize the eighth register set and the connection would be completed in the same manner as previously described.

Referring now to Fig. 3, the first seven register sets have their terminals 379 and 381 connected by a jumper 380 and have their armatures 3&0 connected by a conductor such as 386 to terminal 387. All of the terminals 387 are connected to a common conductor which extends to the relay 392. The eighth register set, or the register set normally held in reserve, is connected in the following manner: the jumper, such as jumper 380, is cut and the terminal 379 is connected to terminal 383 and the terminal 381 is connected to the terminal 382. At armature 340 the conductor such as conductors 386 is moved from terminal 387 to terminal 388 which in turn is connected to an individual conductor 390 for controlling the relay, 391.

It will now be assumed that the first seven registers are busy and'under such conditions ground at the various seven register sets have been disconnected from the common conductor 389, thereby permitting relay 392 to deenergize. Relay 392, upon deenergizing, removes ground from armature 396 thereby rendering the eighth register set selectable. At armature 397 and its resting contact, relay 392 prepares a circuit for relay 393. At armature 398 and its resting contact, relay 392 connect-s ground to conductor 399 for energizing the all trunk busy relay ATB Fig. 2. Relay ATB, upon energizing, connects ground to the lower winding of all line relays such as 206 at the operators position. The ground connections to the lower inding of the line relays extend over the conductors 131 causing the energization of the relays 104las previously explained. The latter relays, upon energizing, connect ground potentials to armatures 120 thereby rendering the outgoing trunks extending to the operators position busy.

It will now be assumed that a call has come in during the interval in which the last of the seven register sets was seized and the trunks extending to the operators position were made busy. Under this conduction such a call would operate the register selector such as C to seize the eighth register set. The call would then be completed in the same manner as previousl described. However, as soon as the eighth register set is seized, the circuit for relay 391 will be opened due to the removal of ground from conductor 390 whereupon said relay will deenergize and close a circuit for operating relay 393. At armature 394 relay 391 closes a shunt around the armature 396 so that if one of the first seven register sets becomes idle the operation of relay 392 will not interfere in any way with the call being set up on the eighth register set. When relay 393 is energized over the above traced circuit said relay removes ground from conductors 406 and. the dead contacts in the terminal block on the I. D. E, Fig. 4, thereby providing a. plurality of stopping posit ons for the idle register selectors when all eight register sets are busy. As soon as one reg ster set becomes idle the circuit of relay 393 is broken and ground is again applied to the dead contacts.

Having described my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out in the-appended claims:

I/Vhat I claim is:

1. In a telephone system, a group of automatic switches each having a plurality of bank contacts, multiple connections between corresponding bank contacts of said switches, an intermediate distributing frame, a termlnal block on said frame having terminal pins corresponding in number to the number of bank contacts in each of said switches, conductors extending from each one of said multiple connections to corresponding terminal pin, said terminal pins divided in a plural ty of groups, a. group of register sets, said register sets being less in number than the number of said terminal pins and terminating on said frame in terminal contacts, a jumper for connecting each one of said terminal contacts to one of said terminal pins, and other multiple connections extending between terminal pins of different groups by means of which said register sets are multiply connected in an irregular manner to the terminal pins in different groups.

2. In a telephone system, a group of line switches having corresponding bank contacts connected in multiple, and means including an intermediate distributing frame for dividing the bank contacts of said switches into. a plurality of groups and for introducing a slip multiple between bank contacts of said groups.

3. In a telephone system, a group of line switches having corresponding bank contacts connected in multiple, a group of trunks less in number than the number of bank contacts in each of said switches, and means including an intermediate distributing frame whereby the bank contacts of each switch are divided into a plurality of groups and whereby said trunk lines are connected to said bank contact groups in slip multiple connections.

l. In a telephone system, a group ofline switches having corresponding bank cont-acts connected in multiple, agroup of trunks less in number than the number of bank contacts in each of said switches, and means including an intermediate distributing frame for dividing the bank contacts of said switches into a plurality of groups and for cross-connecting said trunk lines to said bank contact groups in slip multiple connections.

5. In a telephone system, a group of switches having corresponding bank contacts connected in multiple, and means for dividing the bank contacts of said switches into a plurality of groups and for producing a slip multiple between bank contacts of said groups.

6. In a telephone system, a group of switches having corresponding bank contacts connected inmultiple means for dividing the bank contacts of said switches into a plurality of groups, a group of trunk lines less in number than the number of bank contacts in each of said switches, and means whereby the corresponding bank contacts in each group are connected to a difl'erent one of said trunk lines.

7 In a telephone system, a group of switches having corresponding bank contacts connected in multiple, means for dividing the bank contacts of said switches into a plurality of equal groups, trunk lines terminating in the bank contacts of one of said groups, an d multiple connections between said groups such that the order of access to the said trunk lines from each of said bank contact groups is different.

8. In a telephone system, a group of preselecting rotary line switches having corresponding bank contacts connected in multiple, and means including an intermediate distributing frame for dividing the bank contacts of said switches into a plurality of groups and for introducing a slip multiple between bank contacts of said groups to eliminate the tendency of a number of switches to line up on the same trunk.

9. In a telephone system, a group of preselecting rotary line switches having corresponding bank contacts connected in multi-. ple, means for dividing the bank contacts of said switches into a plurality of groups,

trunk lines terminating in the bank contacts of one of said groups, and multiple connections between said groups for introducing a slip multiple between bank contacts of said groups to eliminate the tendency of a number of switches to line up on the same idle trunk line when the switches are operated from a multiple of the same trunk line.

10. In a telephone system, a group of preselecting rotary line switches having corresponding bank contacts connected in multiple, an intermediate distributing frame Jior dividing the bank contacts of said switches into a plurality of groups, a plurality of trunk lines less than the number of bank contacts in each of said switches terminating in said intermediate distributing frame in one of said groups, and multiple connections between non-corresponding contacts in said groups at said intermediate distributing frame to reduce the tendency of said switches from simultaneously preselecting the same trunk line when the switches are stepped from a multiple of the same trunk line.

11. In combination, a plurality of multicontact switch banks each comprising groups of contacts, multiple connections between corresponding contacts of the different switch banks, and slip multiple connections between the contacts of the different groups of contacts.

12. In combination, a plurality of multicontact switch banks each comprising groups of contacts, multiple connections between corresponding contacts of the different switch banks, and a cross-connecting rack for multiply connecting non-corresponding contacts of the groups.

13. In combination, a plurality of switch banks each comprising groups of contact sets, multiple connections between corresponding contact sets of said banks, multiple connections between non-corresponding contact sets of the different groups, and connections from the individual contact sets comprising one of said groups to switching devices.

14. In combination, a plurality of switch banks each comprising groups of contact sets, multiple connections between corresponding contact sets of said banks, multiple connections between non-corresponding contact sets of the different groups, connections from the individual contact sets comprising one of said groups to switching devices, and a cross-connecting rack for effecting said last two connections.

15. In combination, a single level switch bank comprising a plurality of groups of contact sets, a cross-connecting rack, and means including said rack for inter-connecting contact sets of the various groups so that the order of access to connected contact sets is diilerent for each group.

16. In combination, a single level switch bank comprising a plurality of groups of contact sets, registering devices connected to the contact sets of one group, and a crossconnecting rack for inter-connecting the contact sets of the various groups so that the order of access to said registering devices is different for each group.

17. In combination, a group of switches having corresponding bank contacts connected in multiple, means for dividing the bank contacts of said switches into a plurality of groups, registering devices connected to the bank contacts of one of said groups, and multiple connections between contacts of said groups such that the order of access to said registering devices from each of said contact groups is different.

In witness whereof, I hereunto subscribe my name this 4th day of December, A. D.

RUDOLPH F. STEHLIK.

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