US1762700A - Connecter switch - Google Patents

Description

L mi2 NYS. m5: *QN N lQk An N. H. SAUNDERS CONNECTER SWITCH Filed April 18, 1928 Imran Ur' NnrmanHEaun/:ZEPS

5* z H`U u v @Y u .mkw@

l ma KK [II .n N

`lune 10, 1930.

Patented June 10, 1930 'airain stares PATENT OFFICE NORMAN H. SAUNDERS, OF HOMEWOOD, ILLINOIS, ASSIGNOR- TO RESERVE I-IQLDING COMPANY, OF KANSAS CITY, MISSOURI, A CGRPORATION F DELAWARE CONNECTER SWITCH Application filed April 1,8,

The present invention relates in general to automatic telephone systems and the principal object, stated briefly, is the provision of an improved connecter switch for use in e a small automatic exchange for connecting with local subscribers lines or with trunky lines extending to a toll recording operators position lor to adjacent branch exchanges.

The improved connecter switches are del0 signed primarily for use in small automatic exchanges in which the capacity docs not eX- ceed a hundred lines, and, in addition to having access to local subscribers lines, have access to groups of trunk lines, one group of which extends to a toll recording operators position while the other groups extend to adjacent branch exchanges. In order to complete connections to the trunk lines, the connectors are directively operated into engage- ZU ment with the lirst trunk line in the group from where, if such trunk line is busy, the connecters automatically hunt for an idle trunk line in the group, and in case all the trunk lines of the group are busy, come to rest on the contacts of the last trunk line of the group and transmit the busy tone to the calling subscriber.

@ne of the features of the invention relates to the'improved impulsing and stept ping control circuits of the connecter for directively and automatically controlling the operation of the connecter switch.

Another feature relates to the method of maintaining the automatic stepping circuit and for quickly switching through on trunk hunting levels by rendering a relay slow to release by short-circuiting the same as long as the switch wipers engage busy trunk lines, y, and by removing the short circuit when an i idle trunk line is encountered to-allow said relay to fall back quickly and establish the switching through circuit.

Another feature relates to the provision of two switching relays for a switch having only a single set of switch wipers and in which each switching relayris operated, when an idle line is encountered, independent of the other, depending, however, upon whether the 5c kswitch has been operated to a trunk hunting 1828. Serial N0. 270,879.

level or to a level in which local subscribers lines terminate.

A further feature relates to the provision of a single condenser of relatively small capacity which is included in the circuit for transmitting a dial tone, a busy tone, or a ring-back tone to the calling subscriber.

In a system of this size, it often happens that it is desirable to meter all completed local connections and also to restrict certain subscribers to local connections, while other subscribers are allowed unrestricted service; that is, the unrestricted subscribers are entitled to originate toll calls and calls to the adjacent branch exchanges, while the restricted subscribers are unable, from their lines, to extend a connection to a toll operator or to a trunk line extending to an adjacent branch exchange. In this manner, the operators know that all callsextcnded thus far are entitled to have their desired connections completed. Another feature, in connection with the above, relates to the novel circuit arrangements by means of which metering and restricted service is controlled over the same conductor.

`In order to provide supervision to the operator in a hundred-line system employing plunger type lineswitches, separate connecter switches, which reverse battery .when the called party answers, were vheretofore provided solely for the use of operators in completing connections to local subscribers, lwhile the regular connecters accessible to the local subscribers lineswitches did not reverse battery when the called partyV answered. It was impracticable, heretofore, to have connecter switches which reversed battery accessible to both subscribers and operators because on local connectionsvhen the calling subscriber hung up `his receiver before the called subscriber, there was danger of the bridge cut-oif armature of the lineswitch fluttering or releasing and re-operating intermittently until the called subscriber hung up. rlfhis fluttering would occur in the following manner: When the calling subscriber replaces his receiver, the line and release relays of the connecter deenergize, and the release relay, upon removing holding ground from the release trunk, causes the release of the bridge cutoff armature of the lineswitch before the plunger arm is effectively withdrawn from the switch banks. As soon asv the bridge cutofi" springs close, a circuit is established from ground through the lower winding `of the line relay of the connecter, through the upper reversing springs of the back bridge relay which is held energized by the called party, through the lineswitch bank contacts, and through the bridge cut-off armature springs ofthe lineswitch to the line relay and battery at the lineswitch. This results in thereenergization of the line relays of both the lineswitch and connecter, the re-energization of the release relay of the connecter before the connecter has had time to release, and the re-energization of the pull down winding of the lineswitch. The release relay of the connecter again connects ground to the release trunk, thereby re-establishing the holding circuits for the ring cut-off and switching relays of the connecter before they could return to their normal positions and for the bridge cut-off windings. Since the bridge cut-'off winding of the lineswitch is Vagain energized, the circuit of the line relay of the connecter isopened at the bridge cut-ofi1 springs with he result that the line relay again deenergizes, causing the deenergization of the release relay. rlhis same cycle of operation is repeated as long as the baclz bridge relay is held in energized position. According to another feature of the invention, the flutteringv e of the calling line switch, as above set forth,

is prevented by providing the back bridge relay with a pair of springs for grounding the release trunk, thereby holding the lineswitch operated until the back bridge relay or connecter switch is released.

These and other features of the invention not specifically mentioned at this time will be better appreciated when the following description is taken in conjunction with the accompanying drawings.

Referring now to the drawings comprising Figs. 1 and 2, there is shown, by meansof the usual circuit diagrams, a sucient amount of the apparatus embodying the principles of the invention to enable theinvention to be described and understood.

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

The line conductors 11 and 12 extend to the exchange, where they terminate in the multipled connecter bank contacts 13 and 14C in thelineswitch PLS, which may briefly be described as the well-known plunger type or Keith lineswitch having a plunger which controls the connect-ionl of the subscribers line to an idle trunk line. The plungers of all the lineswitches are controlled by a common master switch (not shown) in such a manner that the plungers of all the idle lineswitches of the grouparel always standing opposite an idle trunk. A plurality of these lineswitches are given access to Group of trunk lines extending to connecter switches. One of the trunk lines to which the lineswitch PLS has access is shown in the drawing as extending to the improved connecter switch CONN, which is mechanically the same construction as .the well-known Strowger type of switch. The .connecter switch has access to subscribers lines, such 'as A', from certain levels and to a plurality of groups of trunk lines from a special level or levels. Shaft-controlled springs, such as springV 84, which operate when thev switch shaft and wipers are raised opposite a trunk hunting level, are provided in orderto permit a switching through relay to switch the talking conductors straight through to the trunk line in the same manner as in the wellhnown Strowger selector switch. Similar shaft springs, such as 85, are also operated on the special levels in order to prevent the restricted subscribers front-completing connections with thetrunk lines therein. J ust below the connecter is shown the well-known busy, dial tone, and ringing machines which are common to the connecters.,

The substation A is similar to the substation A and is accessible to the connecters over bank contacts 94, 95, and 97. rEhe line of i f battery or ground by way of terminals such as terminals 101, 102, and 103, depending upon whether or not the subscriber is` entitied to unrestricted or 'restricted service.

With the meter connected by the jumper exfil ' the is divided into three groups of trunks, the first group consisting of the first four pairs of contacts, the second group consisting of the next vfour pairs of contacts, and the last group consisting of the last two pairs of contacts. rlhe first group of trunks eXtend to the toll. recording operators position, while last two groups extend to nearby eX- changes. lt will be noted that all but the last pair of test contacts in a group are connected by jumper, such as jumper 106, while the last pair of testcontacts of the group are not connected. This is done in order to permit the connecter to rotate from all busy trunk lines in the group except the last, where if the last trunk is busy the connecter stops and transmits the busy signal to the calling subscriber. The individual subscribers test contacts, such as 95 and 96 (Fig. l), are not connected; therefore, there will be no automatic rotation therefrom in case such line is called and found busy.

Wlith this general description of the drawings in mind, the operation of the circuits will now be described in detail. For this purpose, it will now be assumed tliat subscriber A desired to complete a local connection to the line of subscriber A.

Responsive to the removal of the receiver by the calling subscriber A, a circuit is closed for energizing line relay of the lineswitch PLS as follows ground by way of the master switch supervisory ground lead, the B. C. t). springs 18, subscribers line conductor 12, through the calling subscriber-s loop, subscribers line conductor 11, the B. C. t). springs 17, and through the winding of line relay 15 to battery. Line relay .15 energizes over the above-traced circuit and at armature 16 closes a circuit from ground over the master switch supervisory ground lead for operating the pull down winding 19 of the lineswitch PLS. The pull down winding 1i) energizes and causes the operation of the plunger arm. The operation of the plunger arm forces the bank contacts 21 to 2li, inclusive, into engagement with their associated bank contacts 21 to 24, inclusive, it being assumed that the plungers of the idle li .eswitches of the group containing the lineswitch PLS have been standing oppos' Le this set of bank contacts. ln addition to the operation of the plunger arm, the B. C. a 'mature operates and opens the B. C. O. springs 17 and 18, thereupon opening the ci cuit r the line relay 15. As soon as the plunger closes the line contacts 21 and 21 and and 2li', a circuit for energizing the line relay 2 of the connecter CONN may be traced as fcllows: from ground by way of the lower winding of line relay 26, normally closed sprii p. controlled by armature 3S, resting contact of armature 70 and said armature, conta-ct 2li', contact 24, line conductor 12, over the calling subscribers loop, line conductor 11, Contact 21, contact 21', armature 66 and its resting contact, normally closed springs controlled by armature 37, and through the upper windof line relay 26 to battery. Line relay 26, upc-n energizing, closes a circuit for energizing release relay 27 in series with relay 28. Due to the high resistance of relay 27, relay 26 is not energized over this circuit. Release relay 2?" at armature Ll1 connects ground to release trunk conductor 68 in order to estailish a holding circuit by way of contacts and 23 for the BCO winding 2O of the lineswitch before line relay 15 has had time to deenergize. fit contact l0, release relay 27 prepares a circuit for the discriminating relay which will now energize in case the calling subscribers meter is connected to ground through terminal 103. At armature 41, release relay 27 closes a circuit for energizin the combined change-over and ring cutoff relay 32 as follows from grounded release trunk conductor S8, normally closed off-n mal springs S2 and through the lower winding of relay 32 to battery. At armature 42 release rela-y 27 prepares the impulsing circuit for the operating magnets of the switch, at armature 43 and its resting contact it opens the circuit of the release magnet ELSE and at armature Il?) and its working contactpreparcs a circuit for relays 28 and 29. combined change-over and ring cut-olf relay 32, upon energizing, at armature 62 prepares a locking circuit for itself and at armature 63 prepares the circuit for the vertical magnet VERT. rlhe operation of armatures 60, 6l, and 64 at this time are without effect. At armature 65, change-over relay 32 connects the dial tone machine to the lower talking conductor of the connecter as follows: from armature 65, resting contact of armature and said armature, resting contact of armature Z8 and said armature, the small capacity condenser C, the lower talking condenser, resting contact of armature TO and said armature, to the lower talking conductor of the connecter from where the tone is transmitted to the calling subscriber in the well-known manner. lt should possibly be mentioned here that the combined change-over and ring cut-cli' relay 32 is made slightly slow to pull up in order to permit the discriminating relay to pull np and lock in case a restricted subscriber is calling.

Upon receipt of the well-k tact, to the vertical magnet and battery.

trolled by armature 39 and through the winding of relay 28 to battery. A branch of this circuit continues by way of armature 59, resting Contact ot armature 53 and said armature, interrupter contacts of the rotary magnet, and through the winding of relay 29 to battery. lt should also be mentioned at this time that the normally closed springs can trclled by armaturV 39 close a direct short around the release relay2l to render this relay slow to release. Relays 28 and 29 energize over the above-traced circuit and relay 28 at armature 44 closes a circiut for e; ergi ing relay 3l; at armatures 45 and 4'? completes a new i. l more direct circuit for the relays 28 and 29. lThis circuit may be traced rcm gr und at arn ature spring 89 by way ot armature 48 and its working contact, normally close-d springs controlled by armature 39, to the relay 28 and by way of iature to relay 29. Relay 29, upon ener ing, at armature 49 completes a circuit energizing the vertical magnet l/lEiP- as tollows: ground by way of armature 42, armature 49, armature 63 and its working con- By the operation of the vertical magnet the switch shaft is raised one step, thereby opening the ott-normal springs 82. Relay 32, however, is maintained in. operated position over a circuit extending` from ground the working contact of armature 5"? and the loching contact of armature 52 of relay 32.

lifter the termination ot the first impulse, line relay 25 is again energize-d, thereby reestablishing the circuit for relay 2T. lt should pcssibly be mentioned at this time that the current 'fl-ow rover the circuit through the high resistance win-:ling of relay-27 to relay 28 and 29 is insutl'icient to maintain relays 28 29 in operated position. Relay 28, however, is so adjusted that it will slowly tal baclr only after a long energir/ation or relay 2?. Relay 28, therefore, maintains its matures attracted for the duration of a series of impulses, while the relay is so adjusted that it attracts and retracts its armatures for each impulse. TWhen relay 25 pulls up at the end of the first impulse relay 29 releases and opens the circuit ot the vertical magnet.

Each succeeding impulse or the series operates relay 29 and the vertical magnet to cause the switch shaft to raise the wipers 90 to 93, inclusive, oppositeVA the group in which the called line terminates. Shortly alter the last vertical impulse, relay 28, which has been maintained energized throughout the Vertical impulses, releases and at armature 44 opens he circuit of relay 31 whereupon the latter relay deenergizes. llelay`31, upon deenergizing, at armature 57 opens the locking crcuit of relay 32, whereupon the deenergizes and switches the im ulsing circuit at armature 63 from the vertical magnet .Lucene latter relay armature and its working ccntact,

to the rotary magnet ROTf At armaturel 62 relay 32 opens another point in its locking circuit n and at armature disconnects the dial tone from the lower talking conductor.

The connecter switch is now ready to receive the next series of'impulses for rotating the switch wipers into engagement with the banlr vously described. Each time the impulse repeating relay 29 energizes, a circuit may be vtraced for operating the rotary magnet as follows: grcund by way of armature 42, arh mature-49, armature 63 and its resting contact, armature and winding of rotary magnet RQT to battery. By theoperation et the rotary magnet the switch 4wipers 90 to 93, inclusive, are -directively operated into engagement with the benl: contacts 94 to 97, inclusive. llhe operation of the connecter now depends upon whether the called lineis busy or not. Y Y

It will now be assumed that the line ol substation A is busy when called. Under these circumstances, there will be a ground potential upon the test Contact 95and when the test Wiper 91 comes to rest in engagement lwith contact 95, busy relay '30 willl be energized. lt will be remembered that relay 28, being slow to release, has maintained relay 31 in operated position so that a circuit tor energizing' busy relay 30 may be traced as follows: from ground on test contact 95, wiper 91, resting contact of armature and said armature, normally closed springs controlled by armature 7 3, armature 67 and its resting contact, armaturej56 and it worke ing contact, and through the winding ot' busy relay 30 to battery. Shortly after the termination of impulses, the slow acting relay 28 deenergizes and opens the circuitot relay 31. Relay 31 is rendered slow to release because said relay is short-circuited by the operation of armature 51 of relay 30. Relay 30, upon energizing, at armature 52 opens a point in the circuit of switching relay 34, at armature 53 prepares a circ-uit to wiper 92 which, however, is without eEect at this time, and at armature 54 and its working contact prepares a locking circuit for itself and at its resting` contact opens the initial energizing` circuit for relay 28. Shortly after relay 28 deenergizes, relay 31 deenergizes and at armature 56 and itsresting contact closes a point in the circuit for the switching relay 34 which heretofore has been held open. At the normally closed springs controlled by armature 56, relay 31fcloses a locking circuit for maintaining busy relay 30 in energized position, at armature 58 opens the circuit extending` to the wiper 92, and closes the contacts 59 which, however, at this time are without eect'. The

CII

circuit for maintaining busy relay 30 in energized position may be traced as follows: ground by way of armature 69, armature 43 and its working contact, armature 54 and its working contact, armature 76, normally closed springs controlled by armature 56, and through the winding of the busy relay 30 to battery. At armature 55 and its working con tact busy relay 30 connects the well-known busy tone by way of armature 78 and the small capacity condenser C to the lower talking conductor. The calling subscriber A is now given the busy tone in the well-known manner.

l/Vhen the calling subscriber hears the wellknown busy tone, he will replace his receiver, thereby opening the circuit of the line relay 26. At armature 39 line relay 26 opens the circuit of release relay 27 which thereupon deenergizes and at armature 41 removes ground from the release trunk conductor 88, thereby permitting the release of the calling lineswitch. At armature 42 release relay 27 opens the impulsing circuit to the 'vertical and rotary magnets and at armature 43 and its working contact opens the locking circuit of busy relay 30, whereupon said busy relay releases. At armature 43 and its resting contact release relay 27 closes the circuit for operating the release magnet RLSE as follows ground by way of armature 69, armature 43 and its resting contact, oflnormal springs 83, and through the winding of the release mag net RLSEto battery. The release magnet energizes over the above-traced circuit and restores the switch wipers to the normal position, after which the off-normal springs 83 open the circuit of release magnet in the usual manner. All the apparatus used to extend the connection has now been returned to its nolimal position and may be used for other ca s.

Having explained what occurs when a called line is busy, it will now be assumed that the called line is idle. Such being the case, when the test wiper 91 comes to rest in engagement with the test contact 95, it will find no ground potential and the busy relay 30 will not be energized. Instead, when the slow acting relay 28 falls back, thevcircuit of relay 31 will be opened, whereupon said relay will quickly fall back because the busy relay has not been operated to short-circuit relay 31 at armature 51. As soon as relay 31 falls back, a circuit may be traced for energizing switching relay 34 as follows: from ground by way of armature 42, armature 52, shaft control spring 84 and its resting Contact, upper winding of switching relay 34, resting contact of armature 56 and said armature, resting contact of armature 67 and said armature, normally closed springs controlled by armature 73, armature 8O and its resting contact, test wiper 91, bank contact 95, and winding of the BCO winding of the called lineswitch (not shown) to battery. Upon the closure of the above-traced circuit, the BCO winding of the called lineswitch operates to clear the line of station A from its normal battery and ground connections. Switching relay 34 also energizes over the above-traced circuit in series with thc BCO winding` of the called lineswitch and at armature 74 completes a locking circuit for itself. At armature 72 switching relay 34 prepares the circuit for operating the calling subscribers meter; at armature 73 connects ground to the test wiper 91 in order to hold the called lineswitch; at armature 74 and its two working contacts closes a locking circuit for the lower winding of relay 34 and by the upper contact prepares a locking circuit for the ring cut-on relay 32; at armature 75 opens the rotary magnet circuit; at armature 76 opens a point in the locking circuit of the busy relay 30; at armature 7 8 prepares the circuit for transmitting the well-known ring-back tone to the calling subscriber by way of the small capacity condenser C; and at armatures 71 and 77 connects the ringing current to the line conductors of the connecter for ringing the called subscriber A. The ringing current may be traced as follows: Interrupted generator by way of armature 87, resting contact of armature 64 and said armature, armature 77, wiper 93, line contact 97, through the bridged ringer and condenser at substation A', line Contact 94, wiper 90, armature 71, armature and its resting contact, and through the upper winding of ring cut-off relay 32 to battery. The ring-back tone extends from armature f-r- 1 lr l by way of armature (8 and the small capacity condenser C to the lower talking conductor from whence it is transmitted to the calling subscriber in the usual manner.

TvVhen the called subscriber answers, the ring cut-off relay 32 energizes and at armature 62 completes a locking circuit for itself. At armatures 60 and 64- relay 32 disconnects the ringing current from the called line and completes the talking circuit between the call ing and the called subscribers. In addition, relay 32 at armature 61 completesA a circuit for energizing the calling subscribers meter magnet 100 over the following circuit: ground by way of armature 79, armature 72, working contact of armature 61 and said armature, armature 40, contacts 22 and 22, through the winding of meter magnet 100, terminal 101, jumper, and terminal 102 to battery. The calling subscribers meter is operated over this circuit to register the call.. Responsive to the operation of the ring cutoff relay a circuit is closed for energizing the back bridge relay 25 as follows: ground by way of lower winding of back bridge relay 25, working contact of armature 64 and said armature; armature 77, wiper 93, bank eontact 97, the subscribers loop, bank contact 94, wiper 90, armature 7l, armature 60 and its loop.

In practice, it has been found necessary to have the back bridge relay ground the release trunk in order to prevent the fluttering of the calling lineswitch. This difficulty, however, is not encountered when there are intervening switches between the calling lineswitch and the connecter switch. l-leretofore, the fluttering of the calling lineswitch was apt to occur when the calling subscriber hung up before the called subscriber. After conversation, assuming that the calling subscriber is the first to replace his receiver, the

connecter line relay releases and at armature 39 opens the circuit of the slow to release relay 27. Assuming that the back bridge relay at armature'36 does not ground' the release trunk conductor 88, the release relay 27 upon d'eenergizing will, in the assumed case, remove ground from release trunk conductor 88 thereby opening the energizing circuit of the BCO winding 20 of the calling lineswitch. When the circuit to the BCOl winding is opened theBCO armature will release and permit the closure of springs 17 and 18 whereupon a circuit may be traced for'energizing line relays l5 and 26 as follows ground by way of lower winding of line relay 26, armature 37 and its working contact, resting contact of armature 66 and said armature, contacts 21 and 2l, contacts 17 and to the winding of line relay l5 to battery. Line relay 15 and line relay 26 will energize in seriesy over the above-traced circuit. At armature 39 line relay 26 again completes the circuit for slow to release relay 27 before release relay 27 has had time enough to permit the release Vof the ring cut-oli" and switching relays and before the closure ofv the release magnet circuit through armature 43 is edective. In this manner the release relay'27 is again energized and again grounds the release trunk conductor 88 to again cause the operation of the BCO armature springs. VDue to the operation ofthe BCO armature thek circuits of the line relays are opened with the result that the circuit of the slow to release relay 27 is again opened. This intermittent operation Vof the line. relays and the slow to release relay 27 continues until the called subscriber hangs up or until the circuit of the back bridge relay 25 is opened. Since, however, in the present case the back bridge relay 25 at armature 36 grounds the release trunlr conductor 88, it is impossible for the BCO armature to release and close the circuits to the line relays of the lineswitch and while the back bridge relay 25 is maintained When i energized by the called subscriber. the release relay deenergizes it closes at armature 43 the circuitfor operating the releasey magnet whereupon said magnet operates and releases the switch. Due to the release of the y;

switch the circuit of the back bridge relay is opened by the release of the ring cut-ofi:l and switching relays or when the wipers 90 and 93 are removed from the bankcontacts of the called line in case the ring cut-0E and switching relays are slow in releasing. lBack bridge relay 25, upon releasing, removes groundv from the release trunk conductor 88 thereby permitting t-he calling lineswitch to return to normal position. In case the called sub scriber is the first to replace his receiver the back bridge vrelay releases and straightens out the current flow so that there is no danger of'causing the lineswitch to flutter when the calling subscriber replaces his receiver.

Having described the detailed operation of the connecter CONN in establishing a conf nection between subscriber A and subscriber' A', a detailedV description will now be given of the operation whenthe subscriber A desires to complete a connection with an idle trunk line in one of thegroups in the re- 'j strlcted level. The operation of the connecter'is the same regardlessof whether the subscriber is calling the tollrecording operl ator or either one of the branch exchanges by way of the restricted level shown in Fig. 2. Responsive to the removal of the receiver at substation A, the lineswitch PLS operates inthe same manner as previously described v to seize an idle connecterswitch.` It will be assumed that the connecter @GNN shown in Fig. l is'the connecter seized bythe lineswitch PLS. The operation of the connecter is'identical with the operation previously de'- scribed with the exception, however, that when the switch shaft wipersr are raised opposite the restricted level shown in Fig. 2 the shaft control springs 84 and 85 are operated. Shaft spring 8a, whenr operated', opens the circuit of the regular switching relay 34 at its resting'contact and at its working contact prepares the circuit for the switching through relay 33. Switching through relay 33, however, does'not energize at this time p because it is necessary for wiper 91 to find negative battery potential. Since the calling` subscriber is an unrestricted subscriber and therefore entitled to extend calls overL the restricted level, the operation of the shaft control spring 85 at this time is without effect because the discriminating relay 35 has not been operated. Since the operation of the connecter is the same regardless of whether connecter is rotated onto the first contact of the group is the same as previously described. lf the first trunk line is idle the connecter will stop and complete the connection to the toll recording operator in the same manner i as described for the connection to the called subscriber rlhe operation of the connecter, however, is different in case the first trunk line is busy. Assuming that the first trunk line is busy, a circuit may then be traced for' the busy relay 30 as follows: from ground by way of test contact 104C, test wiper 91, resting Contact of armature 80 and said armature, normally closed springs controlled by armature 73, armature 67 and its resting contact, armature V56 and its working contact, and through the winding of busy relay to battery. lt will be remembered that relay 28 is slow to release after the end of the rotary impulses and therefore relay 31 is held by relay 28 until relay 28 releases. Before relay 28 releases, however, the busy relay 30 is energized over the above traced circuit and at armature 5l prepares the short circuit for relay 31 so as to render relay 31 slow to release as soon as the normally closed springs controlled by armature lll have closed. As soon as relay 28 releases a circuit for energizing relay 29 may be traced as follows: ground by way of test contact 104.-, jumper 106, lower test contact engaged by wiper 92 and said wiper, armature 58, armature 46, working Contact` of armature 53 and said armature, interrupter springs of the rotary magnet, and winding of relay 29 to battery. Relay 29, upon energizing, at armature 48 opens the short circuit around the relay 31 and at the same time substitutes a circuit for maintaining relay 3l in energized position. rlhis circuit extends from grounded armature 48 by way of its working Contact and through the normally closed springs controlled by armature del. At armature 50 relay 29 closes u locking circuit for itself as follows: ground by way of armature 69, armature 43 and its working contact, armature a7 and its resting contact, armature 50, interruptor springs of the rotary magnet, and winding of relay 25) to battery. Relay 29 at armature 9 closes a circuit for energizing the rotary magnet. rlhe operation of the rotary magnet causes the switch Wipers to be stepped into engagement with the next set ofv bank contacts associated with the next trunk line. The rotary magnet, near the end of its stroke, opens its interrupter contacts, thereby interrupting the circuit of relay 29 which, thereupon, deenergizes and in turn opens the circuit of the rotary magnet. Relay 29, upon deenergizing, again establishes the short circuit for relay 31 in case the test relay 30 is operated and at armatine 50 opens its own. locking circuit. Assuming that all but he last trunk line extending to the toll recording operator-s position is busy, the ,connecter will be rotated to this last set of contacts in the same mannerl as just described. Assuming that the last trunk line is idle no circuits will be completed for the busy relay or relay 29. Since relay 30 is' not energized relay 3l is not short-circuited, therefore the latter relay immediately deenergizes and closes the circuit for operating the switching-through relay 33 as follows: from ground by way of armature Ll2, armature 52, shaft control spring 84 and its working contact, upper winding of switching through relay 33, resting contact of armature 56 and said armature, resting Contact of armature 67 and said armature, normally closed springs controlled by armature 73, armature and its resting contact, wiper 91, and test contact 107 to negative battery. Switching through relay 33, upon energizing, at armatures 66 and 70 disconnects the line relay 26 and connects the talking conductors of the connecter straight through to the wipers and 93. At armature 68 relay 33 establishes a locking circuit for itself iefore its energizing circuit is opened at armature 67; and at armature 69 opens a point in the circuit of the release magnet in order to prevent the release of the switch when tl e line and release relays 26 and 27 deenergize.

Before release relay 27 deenergizes, however, ground is sent back over the seized trunk line in the well-known manner in order to hold the switching through relay in operated position. rlhis circuit extends from ground which is now connected to test contact 107, wiper 91, resting contacts of arma-- ture 80 and said armature, normally closed springs controlled by armature 73, armature 67 and its working contact, armature 68, and through the lower winding of switching through relay 33 to battery. rlhe remainder of a connection to the toll recording operators position may be set up in anv wellknown manner. The release of line relay 26 and release relay 27 at this time are without effect since the circuit of the release magnet is open. rlhe ground which holds up the switching through relay 33 also extends over the trunk conductor 88 and maintains the calling lineswitch PLS in operated position.

After conversation, ground is removed from contact 107 in the well-known manner, thereby removing the holding ground from the release trunk conductor 88 and from the holding winding of switching through relay 33. Responsive to this removal of ground the lineswitch PLS returns t0 normal posi- LTI sires to complete a connection to subscriber- A. rlhe operation of the lineswitch PLS and the connecter CONN is identical with the operation previously described except that the discriminating relay 35 is energized as soon as the release relay 27 pulls up. The circuit for energizing the discriminating relay 35 may be traced as follows: from ground by way of terminal 103, umper, terminal 101, meter magnet 100, contacts 22 and 22', armature 10, armature 61 and its resting contact,

- normally closed springs controlled by armature 81, and through tile high resistance winding of relay 35 to battery. Due to the high resistance winding of relay 35 the meter magnet 100 is not operated. Since ring cutoif relay 32 is slightly slow to pull up, the circuit of relay 35 will not be opened at armature 61 until relay 35 has had time to pull up. Relay 35, upon energizing over the above-traced circuit, at armature 81 closes a locking circuit for itself by way of grounded release trunk conductor 88 and at armature 79 prepares the circuit for operating the calling subscribers meter. At armature 80 discriminating relay 35 closes a new circuit by way of shaft springs 85 for test wiper 91. Since a restricted level in this case has not been'called the shaft control springs 85 are not operated. The testing circuit now extends by way of armature 80 and its working contact, shaft control spring 85 and its resting contact to the test wiper 91. The operation of the connecter `is the same as previously described with the exception that when the called subscriber Vanswers a circuitv is completed for operating the calling subscribers meter as follows: from ground by way of terminal 103, jumper, terminal 101, meter magnet 100, contacts 22 and 22', armature 10. armature 61 and its working contact, armature 72, armature 79 and its working contact and through the low resistance to battery. The meter magnet 100 is held energized over this circuit until the connecter is released which it doos in the same manner as previously described.

It will now be assumed that the restricted subscriber A attempts to complete a call with one of the trunk lines in the restricted level. In this case the operation of the connecter is the same as previously described and when the scriber should attempt to dial another digit the line relay would operate in the same man* ner as previously described but no impulses would be sent to relays 28 or 29 because at armatures 54 and 53 the busy yrelay 30 has opened the initial energizing circuit for relays 28 and 29.v The switch, therefore, remains standing opposite the restricted level. TWhen the relay 31 deenergizes, which it does shortly after the termination of the vertical impulses, a locking circuit is closed for the busy relay from ground by way of armature 69, armature 43 and its working contact, armature 54Land its working contact, armature 75, normally closed springs controlled by armature 56 and'through the winding of the busy relay 30 to battery. At armature 55 the busy relay transmits the busy tone to the calling subscriber in the same manner as previously described. lt will be noted that by the combined operation of the discriminatingrelay 35 and shaft springs 85the circuit to test wiper 91 is opened so that in case the subscriber should rotate the switch Vwipers the said circuit to the test wiper is open.l

W hen the calling subscriber hears the welllrnown busy tone he will replace his receiver and the lineswitch PLS and connecter CONN will release in the same manner as previously described.

Although only one level has been shown as a restricted level the shaft springs 84 and 85 could also be made to operate on other restricted levels in case the same were provided.

Incomingv calls from the toll recording operators position and calls from the nearby branch exchanges can be made over trunk lines extending to the local exchange and terminat-ing therein in lineswitches similar to the lineswitch PLS. These lineswitches have their bank contacts connected in multiple with the banlr contacts such as the lineswitches illustrated by the lineswitch PLS.V rlhe connecters suchv as the connecter CONN, therefore, are accessible from these trunk lines by way of the lineswitches. YAssuming that the connecter switch CONN has been seized by one of the lineswitches associated with one of the incoming trunks the connecter will be operated in the usual manner to complete the connection to the desired subscriber and when the called subscriber answers the back bridge iso relay 25 will energize and reverse the flow of current in the talking conductors of the trunk line in order to provide supervision to the calling operator. The release of the connections takes place in the well-known manner.

Having described the invention, its utility and operation, what is considered new and is desired to have protected by Letters Patent will be set forth in the appended claims.

. What is claimed is:

l. In a telephone system, a release relay for controlling the release of an established connection, an impulse repeating relay for repeating impulses to cause the establishment of a desired connection, means for shortcircuiting said release relay in order to send impulses to said repeating relay, and a change-over relay connected in parallel with said repeating relay to assist in the establishment of the desired connection.

2. In a telephone system, a release relay for controlling the release of an established connection, an impulse repeating relay for repeating impulses to cause the establishment of a desired connection, means for short-circuiting said release relay in order to send impulses to said repeating relay, a .changeover relay connected in parallel with said repeating relay and connected in the circuit of said release relay, and means controlled by said change-over relay for assisting said repeating relay in establishing the desired connection.

3. In an automatic switch having directive and hunting movements, an impulse repeating relay having only a singlewinding, means for controlling said repeating relay over its Winding to send impulses to the operating magnets to directively operate said switch, and means for energizinganddeenergizing said repeating relay over its winding thereby sending impulses to cause the operation of said switch in its hunting movement.

4'.- In anfautomatic switch having a directivemovement and a hunting movement, an impulse repeating relay for sending impulses to the operating magnets, a change-over relay connected in parallel with said repeating relay' for controlling the change-over from the directive to the hunting movement, means for controlling said change-over andV said repeating Yrelays'to directively operate said switch, and means for energizing and deenergizing said'repeating relay to send impulses to cause the operation of said switch in its hunting movement v 5.l In Van automatic switch having a directive movement and a hunting movement, an impulse repeating relay for sending impulses to the operating magnets, a release relay connected in series with said repeating relay for controllingthe releaseof said switch, means orcontrolling said release. and repeating rrelays to directively operate said switch, and means for energizing and deenergizing said repeating relay to send impulses to cause the operation of said switch in its hunting movement.

6. In an automatic two-motion connecter switch for use in telephone systems, a release relay for controlling the release of said switch, an impulse repeating relay for sending impulses to the operating magnets of said switch to cause said switch to be operated in its two motions, means for sliort-circuiting said release relay in order to send impulses to said repeating relay, and a change-overcontrol relay :tor controlling the change-over from one motionA of the switch to the other connected in the circuit of said release relay and controlled independent of said repeating relay.

7 In a telephone system, a group of trunk lines, a connecter switch having directive and automatic hunting movements, means for operating said switch in its directive and automatic movements to select an idle one of said trunk lines, testing and stepping circuits for controlling the automatic movement of said switch, a relay for controlling said testing and stepping circuits, means for rendering said relay slow acting as long as the switch encounters busy trunk lines, said means ineii'ective when the switch encounters an idle trunk line thereby permitting said relay to fallback quickly, and means responsive to the falling back of said relay for causing said switch to seize said trunk line.

8. In a telephone system, a group of trunk lines, a connecter switch having directive and automatic movements, means for operating said switch in its directive and automatic movements to select an idlev one of said trunk lines, a test relay and a stepping relay in said switch for controlling the automatic movement orq said switch, a circuit for said test relay, a circuit for said stepping relay` a third relay for controlling the circuits of said test and stepping relays, contacts on said stepping relay for closing an energizing circuit for said third relay, and contacts on said test relay for short-circuiting said third relay to render said third relay slow to release during the automatic movement of said switch.

9. In a telephone system, subscribers lines, a connecter switch having access to said lines, a release trunk conductor in said switch, means controlled by a calling subscriber for seizing said switch and for operating said switch to complete a connection to one of said lines, means in said connecter responsive to its seizure for grounding said conductor, a relay in said connecter, means responsive to the called subscriber answering for operating said relay to reverse the direction of current flow to the calling line, and contacts on said relay for connecting an additional ground to said conductor. n

10. In a telephone system, aplunger lineswitch, ak calling subscribers line terminating in said lineswitch, a connecter switch accessible to said lineswitch, a called subscribers line accessible to said connecter,

rection of current flow to the calling line-y switch, means responsive to the calling subscriber replacing his receiver for removing said ground connection from said release trunk conductor and for releasing said switch and contacts on said relay for grounding said conductor to prevent said lineswitch from fluttering due to said reversal.

Y 11, In a telephone system, a calling subscribers substation set, a connecter switch, means including tone circuits in said connecter for transmitting a dial tone, a busy tone, and a ring-back tone to the calling subscriber, and means comprising a small capacity condenser included in said tone circuits for reducing the tone heard by the calling subscriber in order to prevent disagreeable noises in the receiver of the calling subscribers substation set.

12. In a telephone system wherein a connecter switch transmits ya dial tone, a busy tone, and a ring-back tone to the calling subscriber through the same small capacity condenser, va combined change-over and ring cut-0E relay for controlling the transmission of the dial tone, a busy relay Jfor controlling the transmission of the busy tone, a switching relay 'for controlling the transmissi-on of the ring-back tone, said combined relay controlling the disconnection of said ringbaelr tone,'and means for operating said relays for the purposes set forth.

13. In a telephone system, subscribers lines, a connecter switch accessible from said lines and having access to said lines, trunk lines also accessible to said connecter, a measured service device for each subscribers line, some of said subscribers lines having their vdevices connected in such a manner as to restrict such subscribers from operating said connecter to complete connections to said trunk lines, and means including only asingle conductor for operating saiddevices and for preventing the restricted subscribers from operating said connecter to complete connections with said trunk lines.

14. In a telephone system, a subscribers line, other subscribers lines, groups 'of trunk lines, a'connecter switch having access to said subscribers lines and said trunk lines, a measured service device, means including a circuit in said connecter for operating said device responsive to the connecter completing a connection from said subscribers line to an idle one of said other lines, and means including a circuit in said connecter for preventing said subscriber from completing a connection with any one of said trunk lines, said circuits including a common conductor extending :from said device to said connecter switch.

15. In a telephone system, subscribers lines, a connecter switch accessible to said lines and having accessto said lines, trunk lines accessible to said connecter switch, a measured service device for each subscri'bers line, terminal connections for connecting said devices to either battery or ground, the subscribers lines having their devices connected to ground being restricted to connections to said subscribers lines whilepthe subscribers lines having their devices connected to battery are unrestricted andare entitled to establish connections to both the subscribers lines and sai trunk lines, a discriminating relay in said connecter, means for operating said relay over a circuit including a restricted subscribers device responsive to the seizure of said switch by a restricted subscriber, said relay non-operative when a non-restricted subscriber seizes said switch, means controlled by said relay when in operated position for preventing said connecter from completing a connection with any trunk line but not preventing said connecter from completing a connection with any subscribers line if idle,fand normally lclosed and normally open contacts on said relay for operating said devices over a circuit including a portion of said first circuit when the called subscriber answers, said normally closed contacts for operating the non-restricted subscribers devices and said normally open contacts for operating the `restricted subscribers devices dependent upon the operated condition of said relay. i y ,l

16. In a connecterl switch, a release relay for controlling the release of said switch, an impulse repeating relay `for repeating impulses to the magnets of said switch to control said switch in the establishment of a desired connection, and a line relay controlled vby a calling lineV for Yshort circuiting said release relay in order to send impulses to said repeating relay.

17 .Y In a connecter switch, a release Yrelay for controlling the release of said switch, an impulse repeating relay forrepeating impulses to operate said switch, and means for short circuiting said release relay to send impulses to said repeating relay.

18; In av connecter switch, anrimpulse repeating relay :tor repeating impulses to operate said switch, a change-over relay connected in parallel with said repeating relay, and means controlled by said change-over relay for assisting said repeating relay in operating said switch.

19. In a telephone system, subscribers lines, a connecter switch having access to said lines, means controlled by a calling line v for seizing said connecter and operating it to complete a connection to one of said lines, a release trunk conductor in -said connecter grounded when said connecter is seized, and means responsive to the answering of the called subscriber for placing an additional ground on said conductor.

20. In an automatic hunting switch, a relay, means for sending impulses to said relay during the hunting movement of said switch, and means for making said relay slow acting as long as said switch continues its hunting movement and for making said relay quick acting as soon as the hunting movement ceases.

21. In an automatic hunting switch having access to a group of trunk lines, a relay, means for sending impulses to said relay during the hunting movement of said switch, and means for making said relay slow-acting as long as said switch encounters busy trunk lines and for making said relay quick acting as soon as an idle trunk line is found.

22. In an automatic hunting switch, a testing circuit, a relay for closing said circuit during the hunting movement of said switch, and means for making said relay slow acting as long as said switch continues its hunting movement and for making said relay quick acting as soon as the hunting movement ceases.

In witness whereof, I hereunto subscribe my name this 16th day of April, A. D. 1928.

NORMAN H. SAUNDERS.

Images