US2054910A - Telephone system - Google Patents

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US2054910A
US2054910A US28860A US2886035A US2054910A US 2054910 A US2054910 A US 2054910A US 28860 A US28860 A US 28860A US 2886035 A US2886035 A US 2886035A US 2054910 A US2054910 A US 2054910A
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relay
switch
over
switches
primary
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Nelson Stanley Foushee
Shipley Frank Foster
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AT&T Corp
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American Telephone and Telegraph Co Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/0004—Selecting arrangements using crossbar selectors in the switching stages

Definitions

  • This invention relates to telephone systems and particularly to systems of the character in which automatic switching apparatus is employed for establishing connections. l
  • the object of the invention is to enable a more eicient and economical use of the switching and controlling equipment in the establishment of connections through group-selecting stages comprising switches of the cross-bar type which receive the successive series of designation impulses directly from the subscribers dial or other sending device.
  • the present invention secures advantages over rthese prior systems by the use of a more efficient connecting arrangement in which an incoming circuit is selectively connected to an outgoing circuit through primary and secondary switches, these switches being interconnected by link circuits and controlled and operated by associated equipment that receives the digit impulses directly from the dial.
  • each group-selecting stage comprises a plurality of primary and a plurality of secondary cross-bar switches interconnected by iinks, a plurality of incoming circuits or trunks appearing in each of the primary switches, the successive digital series being sent directly to the controlling apparatus associated with each successive stage as the connection progresses from stage tostage, and in which all of the trunks incoming to a particular primary switch are served by the same digit receiving mechanism forming a part Vof the controlling apparatus associated with that stage.
  • Another feature of the invention is a circuit arrangement such that if a plurality of calls reach a group-selecting stage simultaneously they are disposedof one at a time. This prevents interference between two incoming calls seeking trunks in the same outgoing group, and it also enables an incoming call at one primary switch to reach any idle outgoing trunk through any available link without interference from an incoming call at some other primary switch that may be seeking connection to a trunk in either the same or another outgoing trunk group.
  • Another feature is an arrangement for testing the outgoing trunks of a group and the interconnecting link circuits in which each outgoing trunk is tested in conjunction with the link circuit that interconnects the secondary switch in which such outgoing trunk appears andthe particularprimary switch in which appears the calling incoming trunk, and in which the busy condition of the link is determined by the fact that the test circuit therefor is completed through the closed contacts 'D of the link at the primary selector switch.
  • the test relay that tests a particular outgoing trunk is also applied to all links extending from the respective primary switches to the secondary switch in which the outgoing trunk appears, but since 3 only one call can be in progress at a time a complete circuit for the testing relay can be closed only through the primary switch in which appears the call that is in progress.
  • a further feature is a circuit arrangement for 2O operating the magnets of the switches in which a battery potential is applied to the magnets of all link circuits incoming to the particular secondary switch in which appear the idle outgoing trunk to be selected for use at the same time that 25 the opposite potential of the battery is applied to the magnets of al1 links outgoing from the calling primary switch to the several respective secondary switches. Since one of these links interconnects the primary and secondary switches involved, 30 their magnets are operated in series to complete the connection through the stage to the groupselecting stage beyond.
  • the following description Will cover only the operation of an intermediate group-selecting stage of a telephone system embodying this in- 40 Vention since other intermediate stages are practically identical, differing only in the quantities of apparatus required.
  • the initial or line-finder stage, as well as the final or connector stage may be assumed to be of whatever type is best 45 suited to perform the particular functions of these said stages and may consist of any combination of crossbar switches, Strowger switches, Keith line switches or any other suitable equipment, the functions and operation of which are Well 50 known to the art.
  • Fig. 2 shows the invention applied to a plurality of group-selecting stages.
  • Fig. 3 illustrates, in part, one switch of the primary switch group in which appear three trunks TI, T2 and T3 incoming from the preceding stage. Associated with this primary switch Pl is shown the level selector LSI which, under control of dial impulses, selects a linktrunk selector corresponding to the dialed digit.
  • Fig. 4 illustrates, in part, two other primary switches P2 and P3 together with their associated level selectors LSE and LS3 respectively.
  • Appearing in switch P2 are trunks Tl, T5 and T6 inco-ming from the preceding stage.
  • switch P3 appear incoming trunks Tl, T3 and T9.
  • the individual trunk relays for trunks T4 to T9, inclusive, as well as the relays for switches P2 and P3 and the magnets and springs for controllingY level selectors LSE and LS are not shown since these trunks, switches and level selectors are identical with, and function in the same manner as trunks Ti to T3 inclusive, switch Pl, and level selector LSl respectively.
  • Fig. 5 illustrates the iink-trunk selector LTSI associated with the trunks outgoing from the upper level of the secondary switches to the succeeding stage.
  • Fig. 5 also shows a link circuit selector LCS, common to all link-trunk selectors, which selects an idle outgoing trunk in the proper level on a secondary switch to which there is an idle link from the primary switch.
  • Fig. 6 illustrates two other link-trunk selectors LTSZ and LTS3 which are respectively associated with the trunks outgoing from the middle and lower levels of the secondary switches.
  • Fig. 7 illustrates, in part, one switch of the secondary switch group, in which appear the trunks Tll, TiZ, and Tit outgoing to the succeeding stage.
  • Fig. 8 illustrates, in part, two other switches of the secondary switch gro-up, in which appear outgoing trunks Till to TiS, inclusive.
  • Fig. 9 shows how Figs. 3, 4, 5, 6, 7, and Bare to be arranged with respect to each other in disclosing the switches and associated equipment which comprise an intermediate group-selecting stage.
  • Switches Pl, P2, P3, P5, Sl, S2, S3, and S5 shown in Figs. i, 2, 3, 4, "I, and 8 are of the crossbar type and consist brieily off a plurality of sets of contacts arranged in horizontal and vertical rows or units. Associated with each horizontal row of contact sets is a horizontal operating magnet under control of which the said horizontal contact sets are prepared for operation. Associated with each vertical row of contact sets is a vertical magnet under control of which any set of contacts in that vertical row, after being prepared by the operation of its respective horizontal magnet, is operated and held in that position until the release oi the vertical magnet takes place.
  • J. N. Reynolds Serial No. 702,453, led December 15 1933, granted as Patent 2,021,329, Nov. 19, 1935
  • Fig. l for the purpose of simplicity only such portions of three of the primary and secondary switches are shown as is required to illustrate, in general, the manner in which a connection is extended through a group-selecting stage. It will be apparent, however, that the system is applicable to any number of primary and secondary switches and that these said switches may be comprised of any number of horizontal and vertical rows or units of contact sets.
  • trunks such as Ti, T2 and T3, incoming from the preceding stage.
  • the horizontal rows of contacts of primary switch Pi connect to the first Vvertical rows of contacts on the secondary switches SI, S2 and S3 over links Li, L2 and L3, respectively.
  • the horizontal contact rows of primary switch P2 connect to the second rows of vertical contacts on the secondary switches over links L4, L5 and L6, and the horizontal contacts of primary switch P3 connect to the third vertical rows of contacts on secondary switches Sl, S2 and S3 over links Ll, L8 and L9.
  • Each incoming trunk such as trunks TI, T2 and T3, therefore has access to each secondary switch and, through the secondary switches, may be extended to the succeeding stage over outgoing trunks such as trunks Tl l, Ti2 and Tl3. While a single link is shown from a primary to a secondary switch, it will be understood that the invention is not so limited and that more than one link could be used if desired.
  • a horizontal operating magnet such as magnets lill, IUZ and 103
  • a vertical operating magnet Associated with each vertical row of contact sets on the secondary switches Sl, S2 and S3 is a vertical operating magnet, such as magnets H04,
  • a vertical operating magnet such as magnets H04,
  • Each primary switch horizontal magnet connects to a vertical magnet of a secondary switch over a conductor such as conductors itl, H88,
  • a relay such as relay i i@ of switch Pl, which connects battery to the windings of all horizontal magnets of a particular primary switch.
  • a relay such as relay Il l of switch Si, which connects ground to the windings of all vertical magnets of a particular secondary switch.
  • a call extended to this stage over incoming trunk TI may be extended to the succeeding stage over trunks Tl I, Tl2 or TIS outgoing from the secondary switches Si, S2 or S3 respectively, depending upon the selection made by the linktrunk selector which is associated with primary switch Pl at that time.
  • horizontal magnet IDI of the primary switch Pl energizes in series with vertical magnet Hill of the secondary switch SI, over conductor il, upon the operation of relaysY HD and Ill.
  • magnet li in conjunction with the operation of a vertical magnet (not shown) causes the upper set of contacts in the first vertical row of switch Pl to operate.
  • magnet lilll in conjunction with a horizontal magnet (not shown), causes the upper set of contacts in the rst vertical row of switch ⁇ SI to operate.
  • the connection incoming over trunk TI is therefore extended to the succeeding stage over outgoing trunk TII,
  • 02 of switch PI and of switch S2 are energized over conductor
  • a call is extended tothis stage over the incoming trunk T3 and that the link-trunk selector (not shown) associated with switch P3 at this time selects idle trunk TIS.
  • Horizontal magnet II3 oi switch P3 and vertical magnet I I4 of switch S3 are energized in series, over conductor I I2, upon the operation of relays II5 and H0, and the call is extended to the succeeding stage over the lower set of contacts of the rst vertical row of ccntacts of switch P3, link L0, over the upper set of contacts of the third vertical row of contacts of switch S3, and over the outgoing trunk TI3.
  • battery is connected simultaneously to all horizontal magnets of a particular primary switch at the same time that ground is connected to all vertical magnets of a secondary switch, only one primary switch horizontal magnet and one secondary switch vertical magnet can operate, in series, since each link from any primary switch horizontal magnet leads to a separate secondary switch.
  • 30 having a dial ISI is shown terminating in a line switch I32 and a called line
  • the rst of these comprises primary switches PI and secondary switch SI, and the second stage includes primary and secondary switchesP5 and S5. There may, of course, be other stages.
  • a stage may consist of any desired number of primary and Y secondary switches and each switch, in turn, may
  • the group-selecting stage herein disclosed is as sumed to consist of ten primary and ten secondary switches, each switch having ten horizontal and ten vertical rows or units of contacts. For clarity of illustration and description, only the first, second and tenth switch of each of the group ci" ten primary and ten second switches are shown. ln addition, only the first, second and tenth rows of horizontal and vertical sets of contacts for each of the switches illustrated are shown. Three link-trunk selectors are illustrated, one being Mw scciated with the trunks outgoing from each of the secondary switches shown.
  • operates in a circuit from batt-ery through its upper winding, over the lower back contact of vertical magnet 302, ring conductor 303 of trunk TI, ring conductor of the preceding stages, over the subscribers station loop (not shown) ,tip conductor of the preceding stages, tip conductor 300 of trunk TI, middle armature and back contact of magnet 302, lower winding of relay 30
  • instead of being connected directly to the back contact of the make-before-break contacts of relay 305 as in this case for an intermediate stage, is supplied through one winding of a coil through which a dial tone is induced to provide the calling subscriber with an indication that the circuit is ready for dialing.
  • in operating connects ground over its inner front contact to the lower armature of the off-normal springs 305 associated with the level selector LSI, and also operates relay 30'?
  • Relay 30? in operating, connects ground over its upp-er inn-er front contact to sleeve conductor 303 of trunk TI, and also connects ground over its upper outer iront contact, over the neXt-to-inner back contacts of magnets 332, 309 and 3
  • This ground on the sleeve conductors of all of the incoming trunks provides for making this primary switch busy so that no other call can be extended to it until the call which has come in over trunk TI is extended to the succeeding stage.
  • Relay 30? in operating, also partially closes the operating circuit for vertical magnet 302, partially closes the locking circuits for relays 305 and 3I3, and closes, in part, the operating circuit for rotary magnet 3M of switch LSI.
  • releases and reoperates twice in response to the two corresponding open intervals in the subscribers loop.
  • Relay 301 being of the slow-to-release type, remains operated during the intervals in which the circuit through its winding is opened by the release of relay 30
  • energizes rotary magnet 3M of the level selector LSI in a circuit from .ground over the back contact of relay 30
  • Each operation of magnet 3M causes brushes 3I5 and 3
  • Relay 3Ii in operating, operates relay SIS in an obvious circuit.v and connects ground over its right outer front contact and over the right back contact of relay 305 to the winding of relay Relay 3 3, in operating, locks over its right inner front Contact to ground over a previously traced circuit, and opens the circuit to the winding of Y magnet 3 I0.
  • a pair of sequence relays such as relays 3
  • the operating circuits for these relays extend over a chain circuit through the entire group of switches in such manner that only one pair of relays can operate at a time.
  • Ground is connected over the normally closed right contacts of relay 3
  • 9 the operation of only one relay, such as relay 3
  • battery is connected to the winding of relay 449 of the last switch of the primary group and over the left back contact of relay 450 to the winding and left back contact ofthe corresponding relays of each preceding switch, finally connecting to the winding of relay 3
  • relay 450 removes the battery from the windings of the relays corresponding to relay 3
  • a With ground connected to the winding of relay 3
  • 9 in operating, operates relay 320 in an obvious circuit, and removes the ground from the chain circuit extending over the right contacts of relay 4
  • Relay 320 in operating, operates relays 32
  • in operating-connects ground over its front contacts to conductors 326, 321 and 328, thereby grounding the lowest make contact of every set of contacts in the vertical and horizontal rows of switch PI.
  • Relay 322 in operating, connects battery to the windings of horizontal magnets 323, 324 and 325.
  • in operating, associates the trunks outgoing to the succeeding stage from the selected level of each secondary switch, in this case the second level since the digit 2 was dialed, with the link circuit selector LCS. Assuming that the trunk T
  • in operating, opens the circuit over its back contact and the neXt-to-inner front contact of relay 60
  • relay 503 The winding of relay 503 is connected over the outer front contact of the previously operated relay 60I, and over conductor 604, to the sleeve conductor 8
  • VRelay 50i-3 operating after an interval, closes a circuit from ground over its front contact, brush 508, iirst terminal of its associatedbank, conductor 5534, armature and front contact of relay 50
  • Relay 506 is slow-to-operate to provide an interval suflicient for the selection of a link to a secondary switch having an idle trunk before ground is connected to conductor 500, thereby preventing the operation of the horizontal magnet of any other secondary switch.
  • Horizontal magnet 804 operating over the circuit previously traced, prepares the sets of contacts in the middle row of switch S3 for operation, and operates relay 805 in an obvious circuit.
  • Relay 305 in operating, connects ground to the upper windings of vertical magnets 003, 801 and 808.
  • connected battery to the windings of the horizontal magnets 323, 324 and 325 of that switch.
  • horizontal magnet 804 of switch S3, in addition to operating relay 805, also prepares the middle horizontal row of contact sets of that switch for operation. Therefore, upon the operation of vertical magnet 800, the middle set of contacts in the rst vertical row of switch S3 operate.
  • the operation of horizontal magnet 325 of switch PI prepares the set of contacts in the lowest horizontal row in switch Pl for operation, and in addition, closes a circuit from ground over its front contact, left back contact of relay 305, left outer front contact of relay 3i3, lower inner front contact of relay 301, to battery over the inner back contact and through the winding of vertical magnet 302. Magnet 302,
  • Relay 30I in releasing, removes the ground over its inner front contact from the windings of relays 3
  • in releasing removes the ground from the winding of slow-to-release relay 301, and energizes the level selector release magnet 3
  • 1 in energizing, restores brushes 3
  • Relay 301 being slow-to-release, provides for holding vertical magnet 302 operated and for maintaining the busy Vground on the sleeve conductor of trunk T untilthe selected trunk circuit of the succeeding stage has had time to function and return a ground for this purpose.
  • This holding ground Vfrom the succeeding stage is traceable over sleeve conductor 3
  • relay 301 releases and removesY the ground from conductor 336, this conductor having since been grounded from the succeeding stage as set forth above.
  • Relay 301 in releasing, also opens the holding circuit for relay 3
  • 0 in releasing, opens the operating circuits for relays 3
  • 9 in releasing, o-pens the circuit through the winding of relay 320 and again connects ground to the sequence relay chain circuit extending over the normally closed right contacts of relays, 3
  • Relay 320 in releasing, releases relays 32
  • in releasing, removes the ground from conductors 32B, 321 and 323. The purpose for which these conductors were grounded will be set forth in detail subsequently.
  • Relay 322 in releasing removes the battery from the windings of horizontal magnets 323, 324 and 325. Magnet 325 releases and the lowest set of contacts in the first vertical row of switch PI are held in the operated position by vertical magnet 302 which is locked to ground from the succeeding stage.
  • releases upon the release of relay 30
  • Allotter switch A which, together with the link circuit selector relays 50
  • the release of the particular link-trunk selector relay used deenergizes rotary magnet 501 and the brush of switch A advances to the next lower terminal of its associated terminal bank.
  • brush 533 perpares the operating circuits for the horizontal magnets of the i'lrst to tenth or last secondary switch consecutively, thereby changing the order of the first choice trunk in any group. In this foregoing manner, an even distributionof traffic through the groups of trunks outgoing from the various corresponding levels of the secondary switches is obtained.
  • magnets 302 and 856 Since only magnets 302 and 856 remain operated, the common equipment associated with the primary and secondary switches is ready to receive another incoming call.
  • ground is removed from sleeve conductor 8
  • Magnet 302 in releasing, restores the lowest set of contacts of the rst vertical row in primary switch Pi'.
  • Magnet 806, in releasing restores the middle set of contacts of the irst vertical row in secondary switch S3 and this group-selecting stage is thereby restored to normal.
  • primary switches P2 or P3, respectively function in the same manner as set forth for switch Pl.
  • switches Sl vand S2 function in the manner identical with the operation of switch S3.
  • 3 opens the chain circuit ground to prevent the operation of relay 449, on a simultaneous call incoming to switch P3, from operating relay 450.
  • the operationrof relay 423 of switch P2 opens the operating circuit for relay 319, to prevent the operation of relays 3i@ and 320 on a simultaneous call incoming to switch Pl.
  • the operation of relay 450 opens the operating circuits for relays 3
  • 9 opens the ground Similarly, secondary mally closed right contacts of relays 3
  • level selector LSZ will step its brushes to the terminals of its associated bank, the number of steps taken corresponding to the dialed digit.
  • the off-normal springs (not shown) of level selector LSZ operate and close the operating circuit for relay 4
  • 9 operates but, since there is no ground on its right front contact, it does not cause relay 420 to operate.
  • the call over switch P2 is not cut through to the link-trunk selector since ground over the right front contact of relay 420, and over brush 4
  • 9 releases and closes ground to the sequence chain circuit over its normally closed right contacts, thereby permitting relay 420 to operate.
  • Relay 420 in operating, completes the operating circuit for the link-trunk selector relay associated with the particular level dialed, and the call incoming to switch P2 is extended in the manner identical with that hereinbefore described for the call incoming to switch PI.
  • relays 449 and 450 associated with switch P3 remain operated until the call has been extended to the succeeding stage.
  • RelayV 450 in operating, removes the battery over its left back contact from the chain circuit extending to the winding of relay 4 I9, and over the left back contact of relay 420 to the winding of relay 3
  • relays 449 and 450 release.
  • Relay 450 in releasing, reconnects battery to the windings of relays 3
  • 9 operates, in turn operating relay 320 thereby closing the operating circuit for the associated linktrunk selector relay over brush 3
  • the call incoming over switch PI is now extended through the stage in the manner hereinbefore described.
  • 9 in operating, also removes ground from the chain circuit extending over the right contacts of relays 4
  • the call incoming over switch P2 now awaits the release of relay 3
  • Trunk TI which at this time is already in use, has its sleeve conductor 308 grounded from the succeeding stage over Aa previously traced circuit.
  • Relay 339 therefore releases and reoperates ten times in response to the ten dial pulses corresponding to the digit 0.
  • rotary magnet 394 advances brushes 3
  • 8 operates in a circuit from battery through its winding, over the lower contacts of springs 306, to ground over the inner front Contact of relay 339.
  • 8 in operating, operates relay 3
  • Relay 320 in operating, operates relays 32
  • Relay 322 in operating, connects battery to the windings of horizontal magnets 323, 324 and 325.
  • Relays 696 in operating, associates the trunks outgoing to the succeeding stage from the lowest level (which corresponds to the dialed digit 0) of each secondary switch with the link circuit selector LCS.
  • and 502 operate since the trunks associated with these relays are busy.
  • may be traced from battery through the winding of the relay, fourth inner front contact and armature of relay 605, over conductor l, to ground from the succeeding stage over sleeve conductor '
  • Relay 532 operates in the circuit from Ybattery through its winding, over the seventh inner front contact and armature of relay 60B, conductorV 308, to ground from the succeeding stage over sleeve conductor 320 of trunk T
  • 9 of the last secondary switch of the group is assumed idle at this time but, since the link consisting of conductors 333, 334 and 8
  • Relay 503 operates in a circuit from battery through its Upon the operation of the off-normalVY winding, over conductor 510, neXt-to-outer front contact and armature of relay 333, conductor 333,
  • Relay 8I9 also operates in a circuit from battery'through its winding to the ground on conductor 338, the circuit for which has just been traced.
  • Relays 53E, 532 and 533 in operating, open the circuits to horizontal magnets 133, 82l and 324 of secondary switches SI, S2 and S3 respectively, to prevent the operation of these magnets upon the operation of the slow-to-operate relay 536 the circuit for which was. closed by the operation of relay 606.
  • Relay 335 operates in this aforementioned circuit and locks through its left winding from battery over the right outer front contact of relay 3l3, its left winding and left front contact, toground over the lower middle front contact of relay 348.
  • Relay 335 in operating, removes the direct ground over its left outer back Contact from the lower winding of relay 339 and connects ground through the left winding of transformer 332, over its left outer armature and front contact to that point instead.
  • the right winding of transformer 342 connects to a source of a characteristic busy tone over conductors 343 and 344. This busy tone is induced in the left winding of transformer 332 and thence to the calling subscriber since relay 339 is operated over the calling subscribers loop.
  • Relay 305 in operating also opens the operating circuit for relay 3l9.
  • Relay 3l9 in releasing, r'eleases relay 323, connects ground over its normally closed right contacts to the sequence chain circuit extending through the other primary switches of the group, and, in addition, opens the operating circuit for relay 636 which releases.
  • Relay 329 in releasing, releases relays 32
  • Relay 32H in releasing, removes ground from conductors 325, 321 and 323 thereby releasing relay 8l9 which was being held operated by the ground on conductor 326 over cross-point 331 and conductor 338.
  • Relay 322, in releasing opens the circuits from battery to horizontal magnets 323, 324 and 325.
  • Relay 605 in releasing, opens the circuits through the windings of relays 531
  • the release of relay 8I9 opens the chain circuit between conductors 822 and 823.
  • Relays 395, 3l3, 3I8, 339 and 349 remain operated pending disconnection.
  • relay 339 releases due to the opening of the subscribers loop by the switchhook contacts.
  • release magnet 3 l1 of the level selector LSI is energized from battery through its winding, over the upper contacts of springs 333, left inner front contact of relay 3I3, lower outer front contact of slow-to-release relay 340, to ground over the back contact of relay 339.
  • 1 causes brushes 3l5 and 3
  • Relay 339 in releasing, also opens the circuit through the winding of relay 343'.
  • the release of relay 340 also removes the ground over its upper front contacts from the sleeve conductors 3H and 3l2 of trunks T2 and T3 respectively, and these trunks may now be selected in the preceding stage by another call.
  • relay 199 operates if the link between that primary switch and secondary switch Sl is in use.
  • relay 825 operates if the link between that primary switch and secondary switch S2 is in use.
  • the contacts of relays 139 and 825 parallel the twO lower multiple cross-points in each horizontal row oi contact sets in secondary switches SI and S2 respectively.
  • the operation of either relay 103 or 825 causes the all-trunks-busy chain circuit to be extended over secondary switch SI or S2 since the outgoingtrunk in the desired level, although not busy, is unavailable due to its associated link being in use.
  • the all-trunks-busy chain circuit is completed over the entire secondary switch group'and provides for the operation 0f relay 335 yof switch PI or the corresponding relay of any other primary switch being used, and a busy tone is returned to the calling subscriber in the manner hereinbefore described.
  • each of said switches comprising rows of separately operable contacts and coacting bars for operating the same, and means responsive to the impulses incoming to a stage for selectively operating the bars of the primary and secondary switches thereat.
  • a plurality of selecting stages each comprising a number of primary .and a number of secondary cross-bar switch-es, links interconnecting each primary and each secondary switch, means for sending successive series of designation impulses directly to the successive stages, and means responsive to the impulses incoming to a stage for selectively op-i' erating the primary and secondary switches thereat.
  • a plurality of selecting stages each comprising a number of primary and a number of secondary cross-bar switches, links interconnecting each primary and each secondary switch, a plurality of groups of trunks outgoing from the secondary switches, each group having trunks appearing in a plurality of said secondary switches, means for sending successive series of designation impulses directly to the successive stages, and means responsive to the impulses incoming to a stage for selectively op" erating the primary and secondary switches thereat.
  • a series of groupseiecting stages each comprising a plurality of primary and a plurality of secondary cross-bar switches, impulse receiving mechanism associated with each of said stages, means for sending the successive series of impulses of a wanted designation directly to the impulse receiving mechanisms at the corresponding stages, and means responsive to the receiving mechanism at each stage for selectively operating the primary and secondary switches thereat.
  • serially related group-selecting stages each comprising a plurality of primary and a plurality of secondary cross-bar switches, a plurality of trunks incoming to each of said primary switches, impulse receiving mechanisms, each serving to receive the impulses incoming over any one of the trunks appearing in a primary switch, means for sending the successive series of impulses of a wanted number directly to the mechanisms at the corresponding stages, and means controlled by said mechanisms for operating the primary and secondary switches at the respective stages.
  • serially related group-selecting stages each comprising a plurality of primary and a plurality of secondary cross-bar switches, a plurality of trunks incoming to each of said primary switches, impulse receiving mechanisms, each serving to receive the impulses incoming over any one of the trunks appearing in a primary switch, means for sending the successive series of impulses of a wanted number directly to the mechanisms at the corresponding stage- ⁇ means effective when impulses are being received over one oi said trunks for rendering busy all other trunks incoming to the same primary' switch, and means controlled by said mechanisms for operating the primary and secondary switches at the respective stages.
  • a group selecting stage comprising a plurality of primary and a plurality of secondary cross-bar switches, groups of incoming trunks, each group appearing in a separate one of said primary switches, trunks outgoing from said secondary switches, links interconnecting the primary and .secondaryY switches, impulse receiving devices individual respectively to said primary switches and responsive to a call on one of the incoming trunks for selectively operating the corresponding primary switch and one of said secondary switches to extend the call to an outgoing trunk and means effective when a number of incoming calls appear simultaneously for causing said calls to be extended one at a time through said switches to the outgoing trunks.
  • a group-selecting stage comprising a plurality of primary and a plurality or" secondary switches, trunks incoming to said primary switches, trunks outgoing from said secondary switches, link circuits interconnecting each primary switch with each of the several secondary switches, and means for testing the outgoing trunks and the link circuits comprising a test circuit extending to each of said outgoing trunks and a test circuit for each of the link circuits extending through contacts of the corresponding primary switches.
  • a group-selecting stage having primary switches and secondary switches thereat, trunks incoming to the primary switches, trunks outgoing from the secondary switches, link circuits, each primary switch having one of said link circuits extending to each of the secondary switches, test relays for testing the condition of said outgoing trunks. and the condition of said link circuits, a test circuit for each outgoing trunk extending to the winding of a particular test relay corresponding thereto, a test cir-cuit for each of the links having access to such outgoing trunk extending to the winding of said relay, and means for closing the test circuit 01 any one of said links through contacts of the corresponding primary switch.
  • a group-selecting stageI comprising a plurality of primary cross-bar switches and a plurality of secondary cross-bar switches, link circuits interconnecting said primary and secondary switches, operating magnets for said primary switches, each magnet individual to a particular one of said link circuits, operating magnets for said secondary switches, each magnet individual to a particular one of said link circuits, and means for applying a source of potential to a plurality of magnets at said secondary switches and to a plurality of'magnets at said primary switches to cause the simultaneous operation in a series circuit of a desired magnet at the secondary switch vand a desired magnet at the primary switch.

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US28860A 1935-06-15 1935-06-15 Telephone system Expired - Lifetime US2054910A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US28860A US2054910A (en) 1935-06-15 1935-06-15 Telephone system
CH234264D CH234264A (de) 1935-06-15 1936-06-15 Telephonanlage.

Applications Claiming Priority (1)

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US28860A US2054910A (en) 1935-06-15 1935-06-15 Telephone system

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US2054910A true US2054910A (en) 1936-09-22

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2559702A (en) * 1946-02-23 1951-07-10 Kellogg Switchboard & Supply Selector switching system
DE967404C (de) * 1954-07-02 1957-11-07 Standard Elek K Ag Schaltungsanordnung fuer Gruppenwahlstufen in Fernmelde-, insbesondere Fernsprechanlagen, mit Mehrfachschaltern nach dem Kreuzschienenprinzip

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2559702A (en) * 1946-02-23 1951-07-10 Kellogg Switchboard & Supply Selector switching system
DE967404C (de) * 1954-07-02 1957-11-07 Standard Elek K Ag Schaltungsanordnung fuer Gruppenwahlstufen in Fernmelde-, insbesondere Fernsprechanlagen, mit Mehrfachschaltern nach dem Kreuzschienenprinzip

Also Published As

Publication number Publication date
CH234264A (de) 1944-09-15

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