US1274654A - Telephone-exchange system. - Google Patents

Description

J. L. WRIGHT.

TELEPHONE EXQHANGE SYSTEM. APPLICATION HLED'OCT. e. 1914.

l g'mfim. Patented Aug. 6, 1918.

3 SHEETSSHEET I.

V/Z f Mai? of /AM@ W J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED OCT. 6, IBM.

Patented Aug. 6, 1918,

3 SHEETSSHEE]' 2.

W$IVESSE6T Ma J. L. WRIGHT.

TELEPHONE EXCHANGESYSTEM.

APPLICATION FILED OCT. 6 I914.

Patented Aug. 6, 1918.

3 SHEETS-SHEET 3.

WITNESSES.-

"UNITED STATES PATENT oFFioE.

JOSEPH L. WRIGHT, OF CLEVELAND, OHIO, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Aug. 6, 1918.

Application filed October 6, 1914. Serial No. 865,261.

To all whom it may concern:

Be it known that I, JOSEPH L'. WRIGHT, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a specification.

My invention relates to telephone ex-' change systems employing automatic switching mechanism for interconnecting subscribersv lines. My invention is applicable to such systems whether of the full automatic or semi-automatic types.

The manner in which the switches are controlled allows two-wire or metallic circuits to be used. In systems employing such circuits for controlling the automatic switches it has been customary to employ a combination of slow and quick acting relays. The quick acting relays are responsive to rapid makes and breaks in the metallic circuits caused by the sending devices and in turn. transmit these impulses to the control magnets of the automatic switches to cause them to assume a piedetermined position. The slow acting relays act in response to current changes of long duration produced at the sending devices and shift the various circuits at the automatic switches and serve to control their release.

With my invention no slow acting relays or retarded devices are used. The impulses from the sending devices which are produced by simply making and breaking the metallic circuit operate designating devices associated with the automatic switches at the central oflice,

Each automatic switch is provided with its individual stepping or actuating circuit After such contacts are rendered selectable the automatic switches travel at their own speed and after selecting the active conpredetermined individual contact in the group to be selected.

In the present instance I have shown my invention applied to a system of the full automatic type, but, of course, it can be equally well applied to systems of the semiautomatic type.

For illustration I have shown in detail the designating means as consisting of a group of step-by-step relays. Relays of this character and for selective purposes are shown in Patent No. 965,976 to J. L. Wright; of August- 2. 1910.

I My invention is illustrated in the accompanying drawings, wherein:

Figure 1 shows a subscribers line equipment.

Fig. 2 shows a first selector switch and its associated designating device.

Fig. 3 shows a connector switch and its associated designating device. Fig, 4 showst-he Wiring of the designating cont-acts associated with a connector switch.

Fig. 5 shows a modified form of designat ng. means consisting of a step-by-step switch.

Referring to Fig. 1, the subscribers station AA is equipped with apparatus usual in common battery systems and in addition is provided with a sending device. In the present instance I have designated this (le vice by means of a push button *0. The operation of the sending device serves to open and close the line conductors and so cause impulses to be transmitted to control the automatic switches.

The first selector switch J (Fig. 2) is of the two-motion type. It first rotates to select the proper group of contacts and then steps, vertically to select a particular contact in the group. The row wiper 33 sweeps over the row designating contacts while the switch is rotating and when an active contact is engaged, the rotary action of the switch is arrested and it then steps in a vertical direction.

The designating device consists of the step-by-step relays marked K, 1-K, etc., and L, 1-L, etc. In the present instance I have shown but five sets of these relays,

and, consequently, have shown but five row designating contacts in association therewith. In practice, however, there would be ten row designating contacts such as shown in Fig. 4:. In providing ten contacts there would, of course, be ten sets of step-by-step relays.

The designating relays are controlled by relay A, which respondsto-impulses transmitted at the subscribers station.

Fig. 3 shows a connector switch X and its associated set of designating relays R, 1R, etc., and S, 1S,- etc. In the present instance I have shown but three sets of designated relays and three sets of row and 1n dividual designating contacts assoc1ated with the switch X. In practice, however, there would be ten sets of contacts and ten sets of designating relays.

The designating contacts in the connector switch X are arranged and connected in accordance with Fig. 4. No. 1 row contact is connected in multiple with No. 1 individual contact of each row or group. The same arrangement is made in connection-with the remaining row and individual contacts. These row and individual contacts are rendered active or selectable by the same set of designating relays.

The switch X like switch J also first rotates and then steps in a vertical direction.

Fig. 5 shows how designating contacts are rendered selectable by means of a step-bystep switch 500. The magnet'50l of this switch responds to the impulses caused by the sending device and engages a particular contact in the bank of a selector or connector switch, as the case may be. As soon as the designating contact is selected by the selector switch, relay 5M is operated and closes the circuit of the release magnet 6-M, thereby causing the switch 500 to. restore.

The details of the various circuits can best be understood by describing the operation of the apparatus in tracing a call from a calling to a called subscriber. For illustration we will assume that subscriber at station AA desires to'converse with a subscriber whose number is 32-1.

The subscriber at station AA removes his receiver and then operates the sending device circuit and causes theoperation of relay A.

springs 40, 26, winding of relay C to battery B. Relay C after operating remains locked to ground through the back contacts of relay M. The operation of relay C connects battery to the locking contacts of the set of relays L, 1L, etc., and K, 1K and also connects battery to a contact of relay A.

The subscriber at AA in operating his sending device causes ,relay A to respond and transmit impulses to the set of designating relays. During the first impulse when relay A restores, the circuit of relay L is completed by the following path: battery B, contacts of relay C, 9, contacts of relay A, 10, contacts of relay K, 11, winding of relay L to ground. The operation of relay L places relay K in condition tobe operated at the next energization of relay A by the following path; battery B, contacts of relay C, 9, contacts of relay A, 12, contacts of relay L, 13, contacts of relay 1L, 14, winding of relay K to ground. The operation of relay K connects ground to No. 1 row contact of the switch J by the following path: ground, contacts of relay etK, 3K, 2K, 1-K and K. The operation of relay K also completes the circuit of the rotary magnet E of the switch J by the following path: ground, contacts of relay K, 29, winding of magnet E, 30, contactsof relay F to battery B,

The next impulse transmitted at the substation causes relays 1L and 1K to be operated and the operation of the latter relay causes ground to be connected to No. 2 row contact of the switch J and to be removed from No. 1 contact. The next impulse at the substation causes relays 2L and 2K to be operated, and the operation of the latter relay causes ground to be disconnected from No. 2 contact but connected to No. 3 contact.

It will be noticed that the operation of relay K completes the circuit of the rotary magnet E. Theoperation of this magnet causes the switch J to step in a rotary direction. At each operation of the magnet E the relay F has its circuit completed by contacts associated with the magnet and in operating opens the circuit of the magnet. This coiiperation between the relay and the magnet causes a vibrating effect and the vibration of the magnet E causes the switch J to step accordingly.

The impulses, however, which are transmitted at the substation are at a faster rate orin advance of the stepping of the switch J controlled by the magnet E, and, consequently, the ground connections to the various row contacts are always shifted in advance of the row wiper After the first set of impulses have been transmitted, however, and which in the present instancearc three in number. there is an interval caused for the next set of impulses. During this interval the wiper 33 engages No. 3 contact which was grounded by the operation of relay 2K. As soon as connection is effected with this contact the circuit of relay M is completed and it in operating remains locked to ground through contacts of the release magnet H of the switch J. The operation of relay M removes ground from the locking contact of relay C and this relay in restorin removes battery from the locking contacts 0' the set of designating relays. These relays which were energized by the transmission of three impulses from the substation restore and the restoration of relay K opens the circuit of magnet E, causing the switch J to come to rest with its wipers 34, 35 and 36 in line with the proper row or group of contacts leading to connector switches.

The operation of relay M completes the circuit of the test relay D of the switch J by the following path: ground, contacts of relay M, cam sprlngs 45, winding of rela D to battery B. The operation of relay completes the circuit of the vertical stepping magnet G of the switch J. This magnet in operating closesits associated contact springs and operates relay F, and this relay in operating opens the circuit of the magnet itself. This action between the relay and the magnet causes a vibrating efiect and the operation of the magnet causes the switch J to step vertically until relay D restores. This relay restores when the test wiper 34 engages an idlecontact leading to a connector switch. As soon as such a contact is found relay D restores, thereby opening the circuit of the magnet G and causing the switch J to come to rest and engage contacts leading to an idle connector switch. The restoration of relay D completes the circuit of the cut-0E relay N by the following path: ground, contact of relays D and M, 23, winding of relay N to battery B. The operation of relay N removes battery and ground re-.

spectively from the windings of relay A and the coil I.

From the foregoing it will be noticed that as soon as connection is effected with an idle trunk, the battery supply relay and coil are When the first'selector switch J engagescontacts leading to an idle connector switch,

relay Y has its'circuit completed as follows I battery B, resistance coil 100, winding of relay Y, test contacts34, contacts of relay D, 7, winding of magnet H to ground. Re lay Y is of low resistance, but is adjusted to operate in series with the winding of the coil 100 and the winding of the magnet H. The magnet H, however, is so adjusted that it will not operate in series with the winding of the relay Y and the coil 100, but it will, however, operate in series with the winding o'f-relay Y alone. ,In addition to relay Y becoming energized as soon as the connector switch is selected, relay 1A will also be operated as it has its winding connected directly to the tip conductor and supplies battery to the calling line while the coil 1I supplies ground to the other conductor eX- tending to the calling line. The operation of relay 1A completes the circuit of the locking relay lC by the following path: ground, contacts of relay 1A, 77, winding of relay 1G, 76, contacts of relay 4M to battery B. I The operation of relay l-C connects battery to the contact of relay 1A which controls the operation of the set of I relays R, 1R, etc., and S, 1S, etc.

The subscriber at station AA operating his sending device the second time causes two impulses to be transmitted, thereby operating relay 1A accordingly. Relay 1A restoring during the transmission of the first impulse completes the circuit of relay S by the following path: battery, contacts of relay 1- C, 64, contacts of relay 1A, 201, contacts of relay R, 69, winding of relay S to ground. The operation of relay 1-A following the transmission of the first impulse completes the circuit of relay R by the following path: battery, contacts of relay 1C, 64, contacts of relay 1A, 65, contacts of relay S, 66, contacts of relay 1-S, 67, wind- .of the switch X by the following path:

ground, contacts of relay 4-M, contacts of relay R, contacts of relay 2M, 97, winding of magnet U, 98, contacts of relay V to battery B.

The operation of magnet U causesits associated contact springs to be closed, thereby operating relay V, which in turn opens the circuit of the magnet U. This action causes a vibrating efl'ect between the magnet "and relay and the operation of the former causes the switch X to rotate. As'soon as the row wiper 1 10 engages No. 2 contact. which '13. grounded, then relay 1-M-is operated. The operation of this relay disconnects battery from the locking contacts-of relays S, 1S,

R and 1R, thereby causing them to restore. The restoration of relay R opens the circuit for controlling the stepping magnets of the switch X. The operation of relay 1M also completes the circuit of relay 2-M by the following path: ground, contacts of relay 1-M, 70, winding of relay 2M to battery B. The operation of this relay disconnects the rotary magnet U and in its place connects the vertical magnet W.

From the foregoing it will be noted that after the second group of impulses have been transmitted and the'designated row has been selectedby the row wiper 110 then the designating relays are released and the circuit of the "ertical magnet WV substituted for that of the rotary magnet U.

The subscriber at station AA transmitting one impulse operates relay lA accordingly, which in turn causes the operation of relays S and R. The operation of relay B connects ground to No. 1,.contact in the designated row, and also completes the circuit of the vertical magnet 1V of the switch X. The operation of the magnet W causes the switch X to step vertically and when the wiper 115 engages No. 1 contact, which is grounded, then relay 3M has its circuit completed and in operating completes the circuit of relay 1M. The operation of this relay (t-M) opens the circuit of the vertical magnet W of the switch X, causing the wipers to rest on contacts leading to the called-for line.

In case the called-for line is busy then the test relay 0 will be operated by current flowing over the following path: ground, test contacts of the called line, test wiper 105, contacts of relay 3-M, winding of relay 0 to battery B.

The operation of relay 0 completes the circuit of the release magnet P, thereby causing the restoration of the switch X. The operation of this relay also connects a suitable busy tone test "to the trunk conductor notifying the calling subscriber that the called-for line is busy. The relay 0 remains locked to ground through the contacts of relay Y. Relay Y is deenergized when the calling subscriber replaces his receiver and it in restoring releases relay 0.

In case the called-for line is not busy then relay 0 will not be affected. The operation of relay 4M completes the circuit of relay T, the action of which closes the tip and sleeve conductors and completes the circuit between the calling and 'called subscribers lines. The circuit of the cut-oil relay of the called-for line, which corresponds to relay N of Fig. 2, is operated by the following path: ground, contacts of relay 1C, (which was restored by the action of relay 4=M) 107, contacts of relay 3M, 106, test wiper 105 to the winding of cut-oil relay N to battery B. The operation of this latter relay disconnects battery from' the relay A and ground from the coil I, thus clearing the tip and sleeve conductors of the called-for line The operation of relay 4-M completes arness the circuit of the ringing relay Z. This latter relay is operated intermittently by the commutator 200 and when operated connects generator current to the called-for line.

When the called subscriber removes his receiver in response to the call, tip relay Q isoperated. The operation of this relay opens the locking circuit of relay 2M and this latter relay in restoring opens the circuit of ringing relay Z.

At the termination of the conversation, the called subscriber replacing his receiver causes relay Q to restore. The restoration of this relay completes the circuit of the release magnet P by the following path: ground, cam springs 101, 72, back contacts of relay Q, 71, back contacts of relays 2M and l- -C, 74, winding of magnet P to battery B. The operation of this magnet causes the switch X to restore to its normal position. The switch in reaching its normal position opens cam springs 101, thereby causing relay 4-M to restore.

The calling subscriber replacing his receiver causes relay 1A to restore. This relay in restoring connects battery between the winding of relay Y and the coil 100 by the followin path: battery B, contacts of relay 1- 62, contacts of relay Y to the winding of coil 100 and the winding of relay Y. The effect. of battery being applied in this manner shunts the coil 100, thereby allowing the release magnet H of the first selector switch J to be operated. The operation of this magnet H causes the restoration of the switch J and also removes ground from the locking contact of relay M causing it to restore. The restoration of switch J removes ground from the winding of relay Y, thereby allowing it to restore, and it in restoring removes the shunt from coil 100.

In case the calling subscriber replaces his receiver first, the first selector switch J is released in the manner previously described and the called subscriber retains control of the connector switch X. If, however, the called subscriber does not respond then the connector switch X, as well as the first connector switch J, is under control of the calling subscriber. In the latter event the release of the switch X is efiected by the circuit of the release magnet P being operated by the following path: ground, cam springs 101, 72, contacts of relay Q, 71, contacts of relay 1A, 73, contacts of relay'1-C, 74, winding of magnet P to battery B.

Referring to Fig. 4, it will be noted that the last set of designating contacts are shown connected to ound. This ground connection is provi ed in case the calling subscriber should start the operation of the apparatus and then re lace his receiver before connection is established. Relay L (Fig. 2) is shown provided with an armature which controls the starting circuit for stepping magnet E of the switch J. The connection is shown in dotted lines in multiple with the connections on relay K. The same provision is made i connection with the connector switch.(F1g. 3) as relay S is provided with a set of contacts connected in multiple to si .iar contacts on relay R.

In case the calling subscriber should remove his receiver and then fail to operate his sending device relay C (Fi 2) would be operated as well as relay L. elay C is operated at the energization of relay A and relay L operated at the denergization of relay A. In such an event relay L being operated would complete the circuit of the rotary magnet E and cause-the switch J to rotate until the wiper 33 engages the permanently grounded designating contact. As soon as this contact is engaged relay M operates in the manner previously described and the switch J will then automatically select an idle switch. As soon as such a switch is selected the release magnetH would be operated in series with the winding of relay Y as relay 1-A would be deenergized as the receiver of the calling subscriber is replaced.

I [and thereby operate relay S. Relay S would complete the starting circuit for stepping magnets of the switch X and this switch would rotate until the last row of designating contacts, which is grounded, is reached. After this operation the switch X would then step vertically until the last designating contact in the row is engaged, whereupon relay 3-'M would become energized and operate relay 4-M. The operation of this latter relay would restore'relay 1C-, thereby allowing relay Y and, the release magnet H to be placed in series and the operation of the magnet would cause the switch J to restore. The restoration of relay 1C also allows the circuit of the release magnet P of the switch X to be completed.

From the foregoing it will be noted that after the tip relay of a selector or a connector switch is operated and should the calling subscriber replace his receiver the initial starting circuits for the switches is completed and they will step just as though the subscriber had actually operated his sending device.

The designating devices,,whether consisting of step-by-step relays or step-by-step switches should respond to impulses delivered at a faster rate of speed than the stepping of the main switches. The speed of the .main switches can be controlled by proper adjustments or.other means well known 1n the art. Instead of depending entirely upon combination with an automatic switch and a control circuit therefor, of means individually associated with said switch for designating any one of a number of contacts,

thereon by changing the electrical condition thereof, a sender associated with said control circuit for variably actuating said designating means, and additionalmeans for said switch for selecting the designated contact.

2. In a telephone exchange system, the combination with an automatic switch having associated contacts, designating means individual to said switch for automatically rendering selectable at Will a particular contact therein by changing the electrical condition thereof, a sender adapted to operate the same, and additional means associated with said switch for selecting the particular contact, substantially as set forth.

3. In a telephone exchange system, the combination wlth an automatic switch having associated contacts, of a control circuit for said switch, of designating means individual to said switch, a sender in said control circuit for operating at will said designating means to automatically render a particular contact. in said switch selectable by changing the electrical condition thereof, and additional means associated with said switch for selecting the particular contact, substantially as set forth.

4. In a telephone exchange system, the combination with.an automatic switch having associated contacts, of means associated with said switch for selecting said contacts, additional step-by-step means individual to .said switch. for rendering a particular one of said contactsselectable by said selecting means by changing the electrical condition of said particular contact, and a sender adapted to operate the same, substantially as set forth. 1

5. In a telephone exchange system, the combination with an automatic switch having associated contacts, designating means individual to said switch for rendering. any one of said contacts selectable by changing the electrical condition thereof, a control circuit for said switch, a sender therein, means associated with said control circuit and operated by said sender for automatically operating said designating means to render any one of said contacts selectable by said switch, substantially as set forth.

- 6. In a telephone exchange system, the combination with an automatic switch having a bank of contacts, of an auxiliary stepby-step device individual to said switch for rendering a particular contact in said bank selectable by changing the electrical condition thereof, a sender adapted to operate the same, and additional means associated with said switch for thereafter selecting the particular contact, substantially as set forth.

7. In a telephone exchange system, the combination with an automatic switch having a bank of contacts, an auxiliary stepby-step device individual to said switch for designating any one of said contacts by changing the electrical condition thereof, a sender for operating said auxiliary device, additional means associated with said switch for selecting said designated contact after the operation of the auxiliary device, substantially as set forth.

8. In a telephone exchange system, the combination with an automatic switch having a bank of contacts, of an auxiliary stepby-step device individual to said switch, of a control circuit for said switch, a sender therein adapted to operate said auxiliary device to designate a particular contact in said bank by changing the electrical condition thereof and additional means associated with said switch for selecting the designated contact, substantially as set forth.

9. In a telephone exchange system, the combination with an automatic switch having a bank of contacts, of a control circuit extending to said switch, a sender therein, of an auxiliary step-by-step device individual to said switch and controlled by said sender for designating a particular contact in said bank by changing the electrical condition thereof, and additional means associated with said switch for selecting the designated contact, substantially as set forth.

10. In a telephone exchange system, the combination with an automatic switch having a bank of contacts selectable thereby, of a metallic control circuit for said switch, a sender therein, an auxiliary step-by-step device individual to said switch and controlled by said sender to designate the particular contact in the bank to be selected by said switch by changing the electrical condition of said particular contact, substantially as set forth.

11. In a telephone exchange system, the combination with an automatic switch having an associated bank of contacts, of a two conductor metallic circuit for said switch, means individual to said switch and responsive to makes and breaks in said circuit for rendering a particular contact in said bank selectable by changing the electrical condition thereof, additional means associated with said switch for selecting said contact. substantially as set forth.

12. In a telephone exchange system, the combination with a plurality of calling and Largest called subscribers lines, means comprising automatic switches for connectin said lines, a set of step-by-step relays individual to each of said automatic switches, impulse sending meansv for controlling the step-bystep relays, and additional means whereby the automatic switches assume positions controlled by their respective sets of relays, substantially as set forth.

13. In a telephone exchange system, automatic switches having associated sets of contacts, sets of step-by-step controlling relays for said switches adapted to determine in advance the particular contacts to be selected by said switches, a sender for operating said relays, and means associated with said switches for selecting the designated contact, substantially as set forth.

14. In a telephone exchange system, subscribers lines, connective links therefor provided with automatic switches, impulse actuated means associatedwith said switches, contact banks for said switches, means controlled by said impulse actuated means for variably designating contacts in said banks by changing the electrical condition of said contacts, and means for causing said switches to move to a position corresponding to the designated contact.

15. In a telephone exchange system, subscribers stations and a central station and metallic circuits interconnecting them, automatic switching apparatus at the central station for interconnecting lines, designating devices individual'to said switching apparatus, means at each subscribers station for varying the flow of current over the two sides of his line in series to produce roups of impulses varying in number accor ing to a predetermined code, said designating devices being responsive to said impulses in the metallic circuit to desi nate by changin the electrical condition thereof the switc contacts to be selected by said switching apparatus whereby said switching ap aratus effects connectlons corresponding to t ecode changes produced by a calling subscriber, substantially as set forth.

16. In a telephone exchange system, a connector switch, a release magnet, a metallic circuit having answering and calling ends,

a relay arranged to be energized by current over the answering end of said metallic circuit, a relay arran ed to be energized by current over the cal ing end of said metallic circuit, means controlled by both of said relays when denergized to operate said release magnet, and means controlled by only one of said relays when denergized to operate said release magnet.

17. In a telephone exchange system. a calling line, a called line, a metallic circuit having answering and calling ends, means for connecting saidcalling line to said answering end, a connector switch for con- 180 necting said calling end to said called line, means for completing a talking connection between said lines, a relay arranged to be energized by current over the answering end of said metallic circuit, a relay arranged to be energized by current over the calling end of said metallic circuit, a release magnet, a circuit for said magnet completed through the armatures and back' contacts of both relays in series before the completion of a talking connection between said lines and a circuit for said magnet'complete through the armature and back contact of only one of said relays after the completion of a talking connection between said lines.

18. In a telephone exchange systein, the combination with an automatic switch having associated test contacts, releasing'means for said switch, a control circuit extending to said automatic switch, means associated with said test contacts comprising a relay and a resistance coil having their windings in series, means exercised over said control circuit for short circuiting said resistance coil through contacts of said relay to eflect the release of the automatic switch, substantially as set forth.

19. In a telephone exchange system, the combination with an automatic switch having associated test contacts, of releasing means for said switch, a control circuit extending to said switch, means predeterminedly associated with said contacts having an appreciable resistance, means exercised over said control circuit for diminishing said resistance to affect the releasin means of said automatic switch over sai test contacts. substantially as set forth.

20. In a telephone exchange system, subscribers stations and a central station, automatic switching mechanism at the central station for interconnecting said lines, designating devices individual to said switching mechanism, a two-conductor control circuit, means associated with said control circuit for varying the flow of current over the two sides of said control circuit in series to produce groups of impulses varying in number according to a predetermined code, said designating devices being responsive to said impulses in'said circuit to designate by changing the electrical condition thereof the switch contacts to be selected by said switching mechanism whereby said switching mechanism eflects connections corresponding to the code which is produced by said means in said control circuit. substantially as set forth.

21, In a telephone exchange system, the combination with automatic switching mechanism having associated contacts, designating devices individual to said switching mechanism, a two-conductor control circuit, sending means associated with said control circuit for varying the flow of current over the two sides of said control circuit in series to produce groups of impulses varying in number according to a predetermined code, said designating devices being responsive to the impulses in said control circuit to designate by changing the electrical condition thereof the contacts to be selected by said switching mechanism whereby said 'series according to a predetermined code,

said designating devices being responsive to said variation of current for rendering selectable certain contacts of said switching mechanism by changing the electrical condition of said contacts. and means for causing the automatic switching mechanism to be set upon said contacts, substantially as set forth.

23. In a telephone exchange system, the combination with an automatic switch. a device individual to said switch for designating the positionvto be assumed by said switch, electromagnetic motive means for said switch, means for operating said designating means step-by-step in accordance with a predetermined code, and additional electromagnetic means for disabling said motive means when the automatic switch assumes a position designated by said device, substantially as set forth.

24. In a telephone exchange system, the combination with an automatic switch having associated contacts, a designating device individual to said switch for changing the electrical condition of any of said contacts to select the position to be assumed by said switch, electromagnetic motive means for said switch, and a sender for variably operating said designating device step by step in advance of said motive means.

25. In a telephone exchange system, the combination with an automatic switch, a designating device individual to said switch, electromagnetic motive means for said switch, means for operating said designating device step-by-step in accordance with a predetermined code, electromagnetic means associated with said switch for disabling the motive means when it assumes a position corresponding to that of the designating device in accordance with said code. substantially as set forth.

26. In a telephone exchange system, the combination with an automatic switch having associated contacts, a designating device individual to said switch for changing the ing associated contacts, an auxiliary device individual to said switch responsive to current impulses transmitted according to a predetermined code, self-acting electromagnetic actuating means for said switch, electromagnetic means controlled by said device for disabling said actuating means when said switch engages a contact corresponding to said code, substantially as set forth.

28. In a telephone exchange system, the combination with an automatic switch, a designating device individual to said switch, said device responsive to current interruptions transmitted in accordance with a-predetermined code, self-acting electromagnetic actuating means associated with said switch, electromagnetic nieans controlled by said designating device for disabling said actuating means when the switch assumes a position corresponding to said code, substantially as set forth.

29. In a telephone exchange system, the

combination with a device for producing a predetermined number of signals, of an automatic switch provided with a plurality of contacts, an auxiliary designating device individual to said switch and responsive to said device for rendering any one of said contacts selectable by said switch by changing the electrical condition of said contacts, additional means associated with said switch for thereafter selecting contacts rendered selectable by said designating clevic'e, substantiall as set forth.

30. In a telep one exchange system, the combination with a two-motion automatic switch having associated contacts, an auxiliary device individual to said switch responsive to current impulses transmitted according to a predetermined code, self-acting actuating means for operating said switch in both directions, and means controlled by said auxiliary device for changing the electrical condition of any of said contacts to determine the positions to be assumed by said switch in accordance with said code.

In testimony whereof I afiix my signature in presence of two witnesses.

JOSEPH L. WRIGHT.

Witnesses:

ANNA MCCUNE, Ana DEHN.

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