US2362619A - Telephone system - Google Patents

Description

Nov. 14, 1944. R. c. DAVIS ETAL 2,362,619

TELEPHONE SYSTEM 1 Filed Oct. 21, 1943 4 Sheets-Sheet 1 FIG.

R CZDAl/IS INVENTORS (H MATT/"ES ATTORNEY W 14, 1944- R. c. DAVIS ETAL 2,362,619

TELEPHONE SYSTEM I Filed Odt. 21, 1943 4 Sheets-Sheet 2 ATTORNEY TELEPHONE SYSTEM Filed Oct. 21, 1943 4 Sheets-Sheet s INVENTORS: R 620,4 l/IS W H. MA TTH/ES ATTORNEY Nov. 14, 1944. c, pm'ns 1 A 2,362,619

TELEPHONE-SYSTEM Filed Oct. 21, i943 4 Sheets-Sheet 4 b Y mag $3 A TTORNEY i this manner.

Patented Nov. 14, 1944 UNITED STATES PATENT OFFICE" TELEPHONE SYSTEM Richard C. Davis, Great Neck, N. Y., and William H. Matthies, Hackensack, N. J assignors to Bell Telephone Laboratories, Incorporated, New York, N.- Y., a corporation of New York Application October 21, 1943, Serial No. 507,062 7 Claims. (01. 119-22) This invention relates to telephone systems and particularly to improvements in automatic telephone systems employing cross bar switches.

An object is to simplify cross bar switching mechanism and the circuit control means therefor for trunk group selections and trunk hunting operations,

Heretofore cross bar switches have been employed in which select rods and hold rods are coordinately arranged to operate contacts at the intersecting points of said two types of rods when actuated. In some instances a common step-bystep mechanism was provided for selecting and operating the select rods, and in other instances the hold rods were similarly selected and oper-. ated, while in still other cases both the select rods and the hold rods were selected and operated in Cross bar switches illustrating these types of mechanisms have been disclosed in the Patents 2,350,458 to F. H'. Hibbard and 2,350,464 A. L. Keller.

It is to switches of these types that the applicants invention may be applied. A feature thereof is in the selector arrangement of line connections and operating circuits whereby a group of outgoing lines may be selected by a calling incoming line and then'by actually establishing a connection through the cross bar switch to the first line in this group, the sleeve conductor thereof may be tested to determine the idle or busy condition of said line. If the test shows that the first line is busy the switch is operated to perform the same test on the sleeve conductor of the next line, whereas in the case the test shows that the first line is idle, the connection through the switch to this line remains and the circuit between the calling incoming line and selected idle outgoing line is completed. To carry out this feature of the invention in its simplest form an incoming line may be connected to contacts at all the intersecting points of the two coordinate select and hold bars of the switch and each outgoing line connected to the contacts at a single cross-point, while the operating mechanism and control circuit arrangement may be such that when the incoming line is seized and a desired series of impulses is received by the stepping mechanism for 'the select bars, said mechanism will select a particular corresponding select bar and actuate it and thereby select a particular level or group of outgoing lines from which a first idle outgoing line will be chosen.

The mechanism for this choosing of a first idle operated to established connections at the crosspoints between these bars and the actuated select bar from the calling incoming line and a succeeding outgoing line in the selected group. After the outgoing lines are multipled to other switches for connection to other incoming lines, some of said outgoing lines may be busy. Thus when the connection is established at the cross-point between the incoming line and the first outgoing line in the selected group and the outgoing line is found to be busy as indicated by a'particular identifying potential on the sleeve conductor, the circuit control is such that the motor and camming mechanism are actuated to return the actuated hold bar to release this connection and to actuate the next succeeding hold bar to establish a connection to the next outgoing line. If the line is idle as indicated by a corresponding identifying potential on the associated sleeve con- 1 ductor this mechanism will stop and hold the hold bar in actuated position and the connection is then cut through between the incoming line and this-idle outgoing line at thecont'acts at this cross-point. V

This invention may also be applied to selector arrangements of incoming lines and outgoing lines when organized in the well-known primary and secondary selector switching arrangement with intermediate links. The means and'mechanism for accomplishing connections of this type embody another feature of the applicants invention'. In this case, a single switch may be arranged with a primary selector switch section and a secondary selector switch section, or separate switches may be; employed if desired. The wiring arrangement, however, is such that each of a plurality of incoming linesterminates in contacts in a separate horizontal level or row of a switch, while the contacts of' each link circuit are arranged in a separate vertical row with the contacts of the outgoing lines in each group arranged in a horizontal level or row so that a corresponding outgoing line in each group may be connected to a separate link. Thus a conmotion from a calling incoming line to an idle outgoing line maybe established by the operation of a horizontal select bar for the calling line and the horizontal select bar for the group of outgoing'li-n'es in which the desired outgoing line is located and a vertical hold bar may be operated for selecting and connecting a particular link and thus connect the calling incoming line at one point to the link and this link at another point to the chosen idle outgoing line in the selected group.

To establish such a connection the seizure of an incoming line causes the corresponding horizontal select bar in the primary switch section to be operated by the associated select magnet. The

subsequent reception of dial pulses over the inline in the primary line section and the idle out- 4 going line in the secondary line section.

To accomplish the necessary testing and connecting in this case, instead of operating the hold bars in succession for the succeeding links to connect them with a calling line and the outgoing lines in the selected group, the usual hold magv nets are provided for the operation of the hold bars in the primary switch section and in the secondary switch section and a special cam switch controlling contact sets in succession may be provided to test the sleeve conductors of the succeeding links and succeeding out-going lines in the selected group. That is, if the sleeve conductor is found busy this busy condition may be because the link is engaged in a connection to an outgoing line in another group than the chosen group 3 while the corresponding outgoing line in the chosen group having access to this link is idle,

on the operation of a select bar followed by the operation of a hold bar, corresponding connections are closed between contacts at the intersecting point of said two bars such as for example are shown at the intersecting point marked 3. In this particular disclosure each select bar is arranged to serve two horizontal rows of contacts by being rotated in one direction or the other as is well known in the art. The operations of these select bars may be controlled by mechanisms of the type, for example, disclosed and described in detail in the above-mentioned Patent No. 2,350,458, F. H. Hibbard. That is, the individual magnets for the operation of the select bars are displaced by two common magnets 5 and 6 and a common mechanism marked generally by the numeral 1 which control the operations of the select bars to be operated in opposite directions or else the link may be engaged with a busy outgoing line in the chosen group. In either case when a busy sleeve conductor'is encountered by the contact set being tested by the cam mecha-- nism, this mechanism will be actuated further to test the next-succeeding contact set and associated sleeve conductor. When an idle sleeve conductor is found, the motor for actuating the cam mechanism is stopped and circuits provided through the actuated contact set whereby the hold magnets of the chosen link areoperated to establish a connection between the calling incoming line and the link 'at the cross-point of the actuated select bar and hold bar-in the primary switch section, and between this link and the outgoing line at the cross-point of the actuated select bar and hold bar in the-secondary switch section. When these connections are established means are provided in the usual manner fdr completing the talking circuit between the calling line and the outgoing line.

This invention has been illustrated in the accompanying drawings, in which:

Fig. 1 discloses a cross bar switch arranged in accordance with the applicants invention;

Figs. 2, 3, 4, and 5 show various details of the mechanism shown in Fig. 1;

Fig. 6 shows a circuit diagram of an automatic telephone system to which the applicants invention has been applied employing a switch of the type disclosed in Figs. 1 to'5; and

Fig. 7 shows a similar circuit diagram for an automatic telephone exchange in which the applicants invention has been applied to an'arrangement using primary and secondary line switch sections and interconnecting links.

Referrin now to the drawings and particularly to Figs. 1 to 5, these figures disclose a cross bar switch structure of the ordinary type with special camming mechanisms for controlling the operating bars. This cross bar switch includes select bars I and hold bars 2 arranged coordinately and with the usual mechanisms whereby to perform their selective functions. With this switch in which there are five select bars and ten hold bars, a vertical shaft is provided shown at one end of the select bars and provided with ten projections I I thereon arranged in a helical formation, while each select bar is provided with a cross-piece l2 havin oppositely extending arms I3 and M with each arm in a position in line with a corresponding projection l l on the vertical shaft ID. This vertical shaft is rotatable in steps by a pawl and ratchet mechanism I5 controlled by the magnet 6. This magnet B, pawl and ratch mechanism I5, and shaft ID are mounted on a frame. l6 which may be shifted by the magnet 5 to swing away from the arms I3 and I4 on the select bars and to be returned to normal by a spring IT. The function of this mechanism is .such that the frame 16, carrying the shaft H] and the pawl and ratchet mechanism l5, and the magnet 6, is shifted in a position where the projections on the shaft would not interfere with the arms on the select bars. The shaft is then rotated in step until a certain projection on the shaft is placed opposite a particular arm. The frame is then released to normal position so that the selected projection will engage the corresponding arm on a corresponding select bar to rotate it'in the proper direction. The shaft now remains in this rotated position after the operation of the select bar. until it is restored to normal position at the time the connection through the switch has been completed when magnet -5 is operated through off-normal contact l8 controlled by shaft in. That is, this succeeding operation of the magnet 5 shifts the frame again and a pawl mechanism I9 is provided which permits the shaftto return to its normal position under tension of the return spring 20 in readiness for succeeding rotation thereof by the pawl and ratchet mechanism l5 and magnet 6 to select and actuate another select bar. These operations will be described more fully hereinafter in connection with the circuits in Figs. 6 and 7.

To operate the hold bars 2 in this switch in succession in accordance with the applicants invention, the arrangment is provided consisting of a motor 25 having a clutch mechanism 26 connected to a shaft 21. This shaft 21 is provided With helically arranged cams 28 which operate individually on levers such as 29 so that for a complete rotation of the shaft 21 the ten different levers have each been operated upon once' The operation of a lever 29 causes the associated bar 2 to' be rotated on its usual knife edge mounting. such as 30, as in any other cross bar switch structure, for completing a selected connection at a cross-point of said bar and an operated select bar. TheshaftiJ hasfa normal position in which it acts on off-normal rcontacts 3| land :thewstoppins 'of the .shaft 2.? in any ipanti'cular position may be accomplishedhy-the opening-10f the clutch 26 of :a clutch magnet :33 and its armature and Operating lever 3.1 so that if the motor 30 is started with 'the shaft 2 in normal position and the clutch is closed, the shaft rmay belrotated to cause levers 23 torrotate the hold bars-'2 inrsuccession untilzacertain desiredhold-baris rotated when the clutch magnet .33 may 'be :operatedto open the clutch .26 :so that the shaft will maintain this particular :hold bar inzopemted position. Then when the connectionheld by this hold is to be opened, the magnet -33 may be :deenergized to "close the clutch to permit "the motor to return :the short "to normal at which gposition the 'motor is stepped lby 'the offenormal contacts opening iihe circuit therefor as will be described hereinafter.

If reference is now made to Fig. :6, the supplicants" invention maybe embodied in the in which the switch :showniin :l igs. 1 .to forms ta part. .In this case this :switch acts "as a :selector switch in which .a single incoming line may be connectedxto an idleroutgoin'g trunk in any one ofa p1urailityoi groups adf :such itrunks. .Arsubscriberfs line, such as '53, may terminate :a usual line switch \51l and the tbrush'es thereof are connected "to a trunk *hun'ting selector switch :52 of the type disclosed in Figs. 1 to 5. These brushes are connected ito-a line -53 'terminzitingzin the vertical rows of contacts at all :of the crosspo'in'tsi'n this switchi52, while the outgoingtrunks may be divided in groups. switch is provided with' =ten horizontal and ten vertical rows of intersecting contacts, teach horizontal row of contacts would constitute :one group of outgoing trunks "of ten trunks each, that is, each trunk is connected at lbut asingle crosspoint; The circuit arrangement is such that on the seizure "of the line switch i l by acalllingsubscriber "50, the selector 53 will operate to select by the reception of a particular number of impulses a corresponding horizontal level oftrunks For example, if the a marticular level iofltrunks in "switch it should be noted thatlrelay fill in operating T010888 a holding circuit or the magnet-,5 :as the assigned energizing circuit ltherefor .is opened at the '01?- normal contact 18 .on thefirstrotary step "of the shaft 10. all the impulses have been sent, the relay 60 releases and thereby causes the :re-

lease of 'the'm'agnet '5 330 that :the shaft 10 now Z8 and'c'auses the first cam 128 to operate on the first. lever Mr-to rotate the firstrhold bar? and thus cause this bar to establish a connection at the cross-pointer this bar and the actuated select bar, for 'exampleyat the cross-point 3 in this figure throughicontacts marked 68. As is the general practicethe trunks I"! outgoing from the selector switches of this type are multipled to corresponding contacts of other :switches :so that any one of these "trunks may been'gaged through some otherrswitoh. ali'wruiik H zto which the incoming line Wis connected 'isbu'sy; :a. ground'will be found on the sleeve :conductor and :the clutch magnet '33 will 'thereforeinot be op'erated "at this and hunt for an idle trunk in this level. The

closes an obvious circuit "for relay 5'! and relay 51 in operatingcloses a circuit for the operation of the magnet '5 over a circuit from battery. winding of magnet 5, off-normal contacts I8 controlled by the shaft J ll and contacts of relay 51 to ground. This magnet 5 now moves theframe in the switch structure 53, shown in detail .in Figs. .1 to .5, in preparation for selections through this switch, that is, this magnet when operating prepares the mechanism .for the selection and operation of a desired select lbar.

To this end the calling subscriber will not transmit aseries of dial pulses which will operate and release relay 55 accordingly. On the first release of relay 55, the relay G ll operates and also the stepping magnet 6 from battery through the windin of this steppingmagnet 6, winding of relay 30, contacts of relays 51 and -55 'to ground. Relay being slow to release remains operated during the pulsing. The succeeding operations and release of relay 555 operate and release the nectionipresent on the sleeve conductor of the idle itmmk which causes the operation of the clutch .magnet 33 "from this battery through the sleeve zconductor antlsleeve contact, for example,

at the rcross point H2 for the trunk 13 throughcontacts of' relay i'fi, winding 'of clutch magnet '33 to ground. The operation of this clutch magnet 33 now opens the clutch 26 to separate shaft '21 from the motorss so that this shaft will now come to rest and maintain the associated "hold bar in actuated position to maintai the connectionat'therctoss-pomt 12 'for the trunk 13 to the incoming line 53. *Clutch magnet '33 also opens the original energizing circuit for the motor at its conta'cts but the motor will be maintained operated =over a olrouit from the source 61, winding of the motor, the off-normaTcontacts 31 controlled by the shatt 21 'to ground at contacts of relay 56; T flhe clutch magnet provides a locking circuit for itself from battery through the contacts of relay 51, contacts of clutch magnet 33, winding of this magnet to' groundl As the connection to the outgoing trunk 13 is now ready I for cutting through to the calling subscriber 5'0',

stepping mag-nevi to rotate the sh t 0 select the relay 56 operates over a circuit frombattery.

- winding of this relay; contacts of clutch magnet 33 to ground. Relay '56 provides 'alocking circuit for itself from "batterythrough its winding and its own contacts to ground on the sleeve conductor to the line finder .51. The above-mentioned operating circuit .I'or the motor 65 is now opened and contact of relay 56 causes it to stop and magnet 56 also-opens the circuit :for the relay-'65 which releases, causing the release of relay 51,, which in turn causes the release of the clutch magnet 33. Relay 56 .a'lsoexten'ds the ground mal.

connection from the line finder 5| to the sleeve of trunk I3. Relay 51' in releasing closes a circuit for the operation of magnet 5 from battery, Winding" of this magnetoiT-normal contacts-I8, contacts of relay 5l to ground. Magnet 5 in operating releases the shaft I to normal and the actuated select bar is thereby restored to nor- The circuits now .remain inthis position until the connection isbrokendown which is accom plished by the removal of ground from the sleeve conductors. The ground causes the release of the relay 56 and this closes the circuit for the motor 65 from source 61 through the'motor, oil-normal contacts 3| toground at contacts of relay 56.

As the-clutch magnet 33 is released the motor 65 Will rotate shaft 21 back to normal position until the off-normal contacts 3I are openedto stop the motor. The return of shaft 21 to normal will, of course, open the connection at the cross-point I2 to release trunk 13. i

Referring now'to Fig. 7, the arrangement is such that a plurality of connections may be es tablished to various groups of trunks from a plurality of different incoming lines. This figure therefore shows a primary selector switch arrangement 80, a secondary selector switch 8| and a special cam switching mechanism 83.- The primary switch is of "the'regular standard type consist of a motor 84-driving through a clutch 85 controlled by a clutch magnet 86, a shaft 81. The clutch 85 is normally open and is closed by clutch magnet 86 when it-is energized. This shaft when in normal position actuates oil-normal contacts 89 and when rotated actuates contacts such as 90 and 9| and others through cams, such as 92 and 93 spirally arranged on 'the shaft-81. That is, one of these sets of contacts and controlling cam are provided for each link such as Hand 96 and others. The switch 80 may have ten lines such as HM and I02, each incoming from a separate line finder such as I03, I04 and I05, and others, and terminating in ten horizontal rows of contacts with ten outgoing links terminating inten vertical rows of contacts. 'Thus ten separate con-' nections may be established through this switch. Each of these ten links terminates also in a vertical row of contacts in switch 8l and at each cross-point in each horizontal row of contacts is connected a separate trunk such as trunk I06 I01 of one group and I08 and I09 of another group in the samemanner as the trunks are connected in the switch shown in Fig. 6;- That is, there will be ten horizontal groups oftrunks with ten trunks in each group by, means of which,

therefore ten links may establish ten separate connections to anyv one of the ten trunks'in the ten groups. Individual equipment is provided for.

each line incoming from a line finder. For example, the group of relays and the circuits shown at IIO are individual'to the first line IOI andthe groups IIIand Hz for other lines. These latter When shaft I0 is released the circuit formagnet is opened at the off-normal contact I8.

If it is now assumed that the subscriber at II5 establishes a connection through the line finder I03 to the equipment I I0, the first result of this connection will be the operation of relay I I 6 from battery and ground through contact of relay I I1, line finder I03 over the loop at the station II5. Relay H6 in operating closes an obvious circuit for relay III! which in turn closes an obvious circuit'for relay I20. The operation of relay I20 prevents connections from any other line finder from being established while the connection from the line finder I03 is in progress as it removes battery connection from a common lead for operating the relay such as I2I or I22 in the line finder circuits III and H2 or other circuits. Similarly, if, for example, relay I2I hadbeen operated, this relay would have removed battery from the circuit for relay I22, while on the other hand a chain circuit through the contacts of the relay would have been broken to prevent relay I20 from extending a connection to seize common equipment at H3. The operation of relay I20 closes an obvious circuit for the operation of the select magnet I25 for this incoming line I0 I so that the connection will be established through contacts in this horizontal row in which this line IOI terminates. The circuit for this magnet may be traced from battery through the winding of this magnet, contacts of relay I20, over the chain circuit through contacts of the intermediate relays I2I and I22 to ground. Another circuit will be established by the operation of relay I20 from battery through the common relay I26, contacts groups have been shown 'in skeleton form only.

A common equipment is provided for all of the incoming lines and is indicated by the numeral I I3.

of relay I20 to ground to prepare the special mechanism 83 of the switches 00 and BI for the selection of an idle link and an idle outgoing trunk group. The immediate results of the operation of the relay I26 is the closing of a circuit from the source of current I2'I through the motor 84 and contacts of relay I26 to ground for the starting of this motor and the operation of the magnet I28 from battery through the winding of this magnet, off-normal contacts I29 for the stepping mechanism and ground at contacts of relay I26.

The dialing of the desired groups of trunks now proceeds by the alternate operation and release of the pulsing relay I I6. With each release of this relay a circuit is completed for the relay I30 and the stepping magnet I3I to battery through the windings of this magnet and relay, contacts of relays I22, I2I and I20 to ground at contacts of relay II6. Magnet I3I steps the shaft I32 to' select a desired select bar in switch 8|.

' R'elay I30 remains operated during the dialing and this relay maintains the magnet -I28 operated from battery through the winding of this magnet, contacts of relay I30 to ground as the assigned energizingcircuit is opened at oil-normalcontact I29 on the first step of the shaft I32. When the dialing ceases, relay I30 released causing the release of the magnet I28 which now causes the corresponding select barto be operated in a manner as described in connection with Fig.

l. The clutch magnet 86 is now operated from essert in rotating as stated will operate in succession the various groups of contacts 90', etc; associated with succeeding corresponding links. It should now be observed that the test performed by the various succeeding groups of contacts 90,- etc, determines whether a link'such as 9501' succeeding links are idle or busy andwhether a tItunk'in the chosen group associated with an' idle link is idle or busy.

If it is assumed that the two'trunks I08 and I01 belong to the group-of trunks chosen by the associated select bar and the first trunk I08 and the first link are busy by being connected at the cross-point I40 or the link 95 only is busy by being engaged for example at the cross point I4'I to trunk I88whi1e trunk I06 is idle, there'will be in either case a ground on the sleeve conductor I42. Thisground is present dueto the fact that under either of these assumed busy conditions =the hold magnets,- such as I35, I 38 for the switches 80 and 8I, arein operated condition if it is"assumed that the linki 95 is engaged in aprevious connection. Hence this previous connection f-i'om an incoming lineto a trunk-provides this ground from the sleeve conductor at the.:-connected line finder over contacts. of a relaycorresponding to relay II I in the individual circuit for the engaged incoming line through the established connection at a cross-point in the switch 80 over the sleeve conductor of'the busy link 95 to contacts of the operatedset, such as 90, to the winding of test relay' I31. Therefore when contacts 90' are; operated to test for these conditions the presence of this ground will prevent the operation of the test relay I31, the windings of which arealso connected to ground. The motor 84will therefore continue to rotate shaft 81 to actuate a. next succeeding group of. contacts such as, for example, contacts 81 and if the associated link 86 is also engaged the same testwill be performed and the shaft 811 will be rotated further. on the other hand, if neither: link 95' nor the trunk I06 is busy, then when contacts 90' are opera-ted -the associated hold magnets I and I36wil1be'actuated over a circuit from battery; windings of these magnets, contacts 90; contacts of clutch magnet 88 to ground at contacts of relay I28; These hold magnets in: operating will actuate the associated hold bars andthus establishuconnec tio-ns at the cross-points I43 and I respectively, and thus connect the line I04 over link'95 and trunk I08. Theseholdmagnets' in operating will close locking circuits for themselves through their own contacts to the sleeve conductor I42, contactsBIl, windings of testrelay I31 to ground. In thiscase test relay I31 will operate over this circuit and open the locking circuit for clutch magnet 85 and provide a circuit shuntin the lefthand winding to ground over its own contacts, contacts of magnet I28, ofi-normal contacts I29 and contacts of relay I26. The clutch magnet in releasing will open the clutch 85 and thus shaft 81 is stopped when contacts 90 operate. As these connections are established, a circuit will now be completed for the operation of relay II! from battery through the winding of this relay, sleeve contacts at the cross-point I43, sleeve conductor I42, contacts 90, one winding of test relay I31, contacts of magnet I28, off-normal contacts I29 to ground at relay I26. Relay III in operating completes the circuit from the calling subscribers line at I I5 over the tip and ring conductors to the trunk I06 and closes a locking circuit for itself through its contacts to ground on the sleeve at the line finder I03. This ground -the relay II-B- which releases and this relay in turn releases relays-II 8 and I20 and relay I2-0- in releasing releases relay I281 Relay I 26' 1 in releasing closes a circuit for the operation ofmagnet I 28 which in operating releases the shaft I32 to normal and this circuit ist'hen opened at the offnormal contact IZS to release magnet I28.- Relay I2 6" alsoopensthe circuit for the circuits for hold magnets I35 and I36 and ground" on thesleeve permits relay I31: to release. The circuit for motor 84 is still closed at the ofi -normalcontacts 89 and the clutch magnet86 vv ill now againoperate from battery through the windingof this magnet; contacts :89, contacts of relay 26 toground to again cause the clutch to engag'e' shaft 811 and rotate itlback-to normal: position when the circuit for the motor M is opened at cit-normal contacts 89 :as-well as. the circuit, for-the clutch magnet'88 so thatthe shaft 8 will now remain'in normal position and the common circuit control circuits 90 will be available for use in establishing other. connectionsthrough the switches 80 and 81'. whenthezsubscriber at 'Ill'5 'relinqui'shes this con nection by replacing his receiver on his-switchhook; theground on the sleeveat the line switch 103 is removed. causing the releas'e o'i relay- II 'I and the release of this relay causes the release of the .hold'smagnets I 35.: and I 36 and switches. 88 and at in releasing" open the connection to the trunk I06 at the points I43 and I40.

Whatis claimed is:

1. In a telephone. system; at cross. bar switch having horizontal. and verticali bars, a. stepping mechanism for selecting and'actuating'any horizontal bar, a common mechanism: for actuating the vertical bars in succession,:contact's. at each cross-point of said coordinate bars; eachsetactm ated on the operation .of the associated horizontal andivertical bars; anin'comi'n line connected to contacts at. each cross-point of said: bars; outgoing lines each connectedat' a. separate crosspoint' to contacts thereattcircuitmeans: responsive to impulses received over" the incomingline a for actuating the 'steppin'gtmechanism' to selectand actuate a: corresponding horizontal bar; and means thereafter operative for actuating the common mechanism to operate the vertical bars in. succession to connect th'e' incoming line with succeeding J outgoing lines until anidle outgoing linesisfoundt 2;. Int. a telephone 1 system; a crossbar switch havinghoriZontal and vertical bars, a stepping mechanism for selecting and actuating any one of said horizontal bars, a motor mechanism for actuating succeedingvertical bars, contact sets at each cross-point of said bars, each set actuoperated horizontal bar is idle or busy and to stop.

the motor mechanism if this outgoing line is idle and to continue to operate the motor mechanism to succeeding outgoing lines if said first line is having select bars and hold bars coordinately arranged, contacts at each cross-point of said bars, an incoming line terminating in contacts at each cross-point, outgoing lines each terminating in contacts at a separate cross-point, means responsive to impulses received over the incomingline for selecting and operating a corresponding select bar, means responsive after a select bar has been operated for actuating the hold bars in succession until a connection is established between the incoming line and a first idle outgoing line over the contacts at the cross-point of said operated select bar and hold bar.

I 4. In a telephone system, a cross bar switch having select bars and hold bars coordinately arranged, contacts at each cross-point of said bars, anincoming line terminating in contacts at each cross-point, outgoing lines each terminating in contacts at a separate cross-point, means responsive after a select bar has been operated for temporarily actuating one hold bar after another to establish a connection between the incoming line contacts and succeeding outgoing line contacts at the cross-points of said operated select bar and said succeeding actuated hold bars to test for busy outgoing lines and when an idle outgoing line is found to maintain the established connection between the contacts at the crosspoint of said hold bar and said actuated select bar and the complete talking connection between said lines.

5. In a telephone system, a cross bar switch having horizontal and vertical cross bars, contacts at each cross-point of said bars, a plurality of incoming lines each terminating in contacts at the cross-points between a particular horizontal bar and all vertical bars, a plurality of groups of outgoing lines, each outgoing line in a group terminating at an individual cross-point between a common horizontal bar to said group and all vertical bars, a plurality of links each terminating in contacts at the cross-points beof a particular group of outgoing lines, means thereafter operative for testing succeeding links to determine whether they are idle or busy and operative when a first idle link is found for actuating the associated vertical bar to connect the calling incoming line with an outgoing idle line in the group selected through the contacts at the cross-points of said vertical bar and said two actuated horizontal bars.

6. In a telephone system, a cross bar switch having select bars and hold bars coordinately arranged, contacts at each cross-point of said bars, incoming lines terminating in contacts at the cross-points of said bars, outgoing lines arranged in groups and terminating in contacts at the cross-points of said bars, links in said switch each having access at the cross-points to all of the incoming lines and to one outgoing line in each group, means responsive to the seizure of an incoming line for actuating a corresponding select bar, means responsive to impulses received over said seizedv incoming line for selecting a group of outgoing lines by the operation of a corresponding select bar, and means thereafter operating to test for and select the first idle associated link and outgoing line in said selected group and connect said idle outgoing line to said incoming line over said idle link by the operation of a corresponding hold bar.

'7. In a telephone system, a cross bar switch having a first and a second group of select bars, a common group of hold bars crossing all of said select bars, contacts at each cross-point of said two types of bars, incoming lines each terminating in the contact at the cross-points where a particular select bar of the first group crosses all of said hold bars, outgoing lines arranged in groups with the outgoing lines of each group terminating at individual contacts at the crosspoints where a particular select bar of the second group crosses all of the hold bars, links in said i switch each terminating in the contacts at the cross-points where a particular hold bar crosses all the select bars, means responsive to the seizure of an incoming line for actuating the corresponding select bar in the first group, means responsive to impulses received over said incoming line for actuating a particular select bar of the second group to select a corresponding group of outgoing lines, and means thereafter operative for testing for a first idle link and a first idle outgoing line in the selected group of outgoing lines, and then actuating the corresponding hold bar to establish a connection at the cross-points where the actuated select bars cross the-actuated hold bar to extend the said incoming line over the select link to the selected outgoing line in the selected group.

RICHARD C. DAVIS. WILLIAM H. MATTHIES.

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