US1376371A

US1376371A - Automatic telephone system

Info

Publication number: US1376371A
Application number: US123267A
Authority: US
Inventors: George A Yanochowski
Original assignee: Kellogg Switchboard and Supply Co
Current assignee: Kellogg Switchboard and Supply Co
Priority date: 1916-10-02
Filing date: 1916-10-02
Publication date: 1921-04-26
Anticipated expiration: 1938-04-26

Description

G. A. YANOCHOWSKI.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FlLED OCT. 2, 1916.

m 9 w v 5 9 Aw u w x m M Q E i F m H/EV r Lam T 7' P H m W EUFQE 4 G. A; YANOCHOWSKI.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED OCT. 2, 1916.

1,376,371; Patented Apr. 26, 1921.

4 SHEETS-SHEET 2.

G. A. YANOCHOWSKI.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED OCT. 2, 1916.

m rT P F. A 0 a4 F m m E M iii 590F475 174/527 Urban/5A z' 22755555 Wag/9% NW G. A. YANOCHOWSKI.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED OCT. 2. 1916.

1,376,371 Patented Apr. 26, 1921.

4 SHEETS-SHEET 4.

n OR m 2 22272755555: JUL/52222721 UNITED STATES PATENT OFFICE.

GEORGE A. YANOGHOWSKI, or cnrono'o, ILLINOIS; ASSIGNOR 'ro xELLooG swrrcn- BOARD AND sunny compan or cnxcaoo, rumors, A CORPORATION or ILLI- NOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Apr. 26, 1921.

Application filed October 2,1918. Serial No. 123,267.

To all whom it may concern:

Be it known that I, GEORGE A. YANO- CHOWSKI, a citizen of the United States of America, residing in Chicago, county of Cook, andState of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates to telephone exchange systems and more particularly to automatic telephone systems of the two-wire or metallic line type of that kind in which the subscribers lines are provided with primary or individual line switches which have access to trunks that terminate in secondary line switches which in turn have access. to trunks that terminate in first selector switches, thereby causing at least two nonnumerical trunking operations before the call reaches the first selector switch or other 4 apparatus.

The object of my invention is the provision of a system of the above type which is provided with rotary primary and second ary line switches, that is, primary and secondary line switches which are each provided with their own individual operating mechanism.

One of the features of my invention is the use of rotary primary and secondary line switches of the type in which the wipers of the switches do not return to normal when a connection is released but remain upon the terminals used in extending the connection from a subscribers line to a first selector. Another feature of my invention is the provision of means in the primary and secondary line switches to permit their wipers to remain stationary in connection with the last bank terminals used when a subscriber initiates a call, providing that the trunks extending from the contacts engaged by the primary and secondary line switch wipers are idle ones, thus providing a system in which a calling subscriber may extend a call through to an-idle first selectorwithout moving either. the primary or secondary line switches but allowing them toremain in their antecedent position. The. provision of switches of this type greatly decreases the average time taken for connecting a subscribers line 'to an idle first selector switch.

Still another feature of my invention is the provision of means for rendering all of the trunks extending from primary line switch groups to a secondary line switch group busy as soon as the first selectors assoclated with the secondary line switch grou become busy. The features as above described and others will be more fullv described in the ensuing specification.

Fora more complete understanding of my inventlon reference is to be made to the accompany ng drawings which illustrate diagrammatlcally the apparatus used in estabhshmg a connection from a calling to a called line, and in which- Flgure 1 shows a calling line and its primary line switch B; and a secondary line swltch to which it has access.

Fig. 2 which is placed to the right of F1g. 1, shows a first selector switch.

F1g. 3, which 1s placed to the right of Fig. 2, shows a connector switch, a called l ne and part of its primary line switch c1rcu1t.

Fig. 4 illustrates diagrammatically one method of extending the trunks from the prlmary line selectors to the secondary line selectors.

Referring to Fig. 1, I show a substation A which is of a Well known form of apparatus, and comprises a calling device CD in addition to the usualsubstation apparatus. The hne conductors 1 and 2 connect the substation A with the primary line switch B.

The line switch B is preferably a ten point rotary switch comprising ten sets of contacts 7, 8, 9 and 10, circularly disposed in a well known manner and having cooperating Wipers 3, 4, 5 and 6, respectively, each and 6 are moved from one contact set to the next. In the selecting operation of the switch B, the wipers are advanced to an idle set of contacts and after conversation is completed they remain in connection with the said contacts until another selecting operation of the switch. The wiper 3 may be called an auxiliary'wiper and each contact 7 leads to a normally open contact 23 of a relay 22, the said relay 22 controlling cera apted to be energized when switch B connects with an idle secondary line selector to extend the circuit of the calling line to said selected secondary line selector. A second cut-ofi' relay 00 is also provided for the switch B, the said relay being adapted to be operated only upon connect1on to the line of substation A as'a called line; The operation of this relay c0 removes thesubstation control of its line switch B. A relatively slow-acting relay R is also provided for the line switch B, the said relay being adapted to be energized upon energization of its associated line relay LR to control certain operations, as will be more particularly pointed out in the ensuing specification. Each line A is multiply connected to contacts their. operat on will be more in the ensulng specification.

201 202 203 of ten connector switches which have access thereto. 4

The secondary line switch D is similar in construction to that of the primary line switch B, and in addition a train of

relays

19, 19 19 is provided. The said chain of relays is associated with a group of secondary switches and is adapted to busy the incoming trunks from the primar groups to the. secondary groups when al of the trunksleading from the group of secondary line switches to the first selector switches are busy. The train of

relays

19, 19 19 brings about the energization of relay 22 to place a ground on conductors 23 to brin about the above result, and fully described The first selector D illustrated in Fig. 2 comprises a set of wipers 24, 25 and 26, and cooperating sets of contacts 27, 28 and 29, divided into ten groups of ten contacts each. The ten groups of contacts are arranged in ten rows, each row containing ten sets of contacts. The wipers are'so arranged that in the operation of the switch they are primarily adjusted in one direction to select a row of contacts, and then secondarily adjusted to select a contact in the selected row. For adjusting the wipers in a rimary direction the primary magnet M and associated ratchet pawl mechanism are provided, while for adjusting the wipers in a secondary direction a secondar magnet SM and associated ratchet mec ianism are provided. Primary off normal springs PON .are adapted to be moved to their alternate position upon the first primary step mary relay PR is connected in bridge of the primary and secondary conductors 1 and S, the said relay being energized upon connection made with its associated first selector switch by current flowing over the calling line. The'relay PR being connected Q in bridge of the 'lineas stated is responsive to any interruption. of its circuit as by means of the calling device CD. A slowacting secondary relay SR is provided which controls the starti of the secondary movement of the switc A slow-acting main release relay MR is also provided .and is adapted to control the release of the switch. A test relay TRis adapted to be energized after the primary movement of the switch and controls the secondary movement of the switch in selecting an idle set of contacts. In the release of the first selector D, secondary magnet SM is again actuated to advance wipers 24, 25 and 26 beyond the last contact in-the selected group, whereby a release awl is actuated to .allow the wipers to erestored by a spring, the restoring movement of the wipers taking a different path from .the actuating movement. In restoring they return from their primary adjustment first and thereafter from their secondary adjustment. From this it will be seen that in a complete opera tion of the switch, that is, in a selecting and releasing operation, the wipers are first moved in a horizontal plane, but in a rotary direction, to a certain row or group of contacts, and thereafter moved in a vertical plane, but also in a rotary direction, to select a contact in the selected group. Then when released, this secondary vertical movement is continued until the wiper passes the last contact in the selected row whereby a release pawl is operated to allow the wiper to restore by a spring first backward in a rotary horizontal direction and thereafter downward in a rotary vertical direction, to normal.

The connector switch E as illustrated in Fig. 3 comprises a switch structure similar to the switch structure of first selector D. The relays, operating magnets and oif-normal contacts of the connector switch E which are similar to the corresponding parts of the first selector D have similar reference characters but with the suffix prime added. The connector switch E also includes a line test relay LT which is adapted, following the connection of the wipers to the terminals of the called line. to cause ringing current to be applied through the medium of an interrupter relay RI to the terminals of the called line if idle, while if the called line is busy a charcuits, but I preferably employ such a switch as is disclosed in patent to William Kaisling for automatlc switch for telephone systems, No. 1,131,140.

The called substation F is equipped similar to substation A and is connected by means of line conductors '1 and 2 to the primary line switch 13 at the central ofiice.

Having described in general the apparatus,

scribed, and we will assume that the number of the called substation F is 243.

To initiate a call the subscriber at the substation A removes his receiver from its switch hook whereby a circuit for line relay LR is established, the circuit being traced from battery through the windin of line relay LR, the normal contact 30 0 relay R, normal contact 31 of relay )0,- the normal contact 32 of relay CO, the line conductor 2, through the substation A, back over line conductor 1, normal contact 33 to ground at normal contact 34. The closing of alternate contact 35-of relay LR closes an energizing circuit for the relay R from battery through the winding of the relay R to ground at alternate contact 35. As the primary line switch is of the rotary non-restor ing type, one of its wipers is always engaging a contact leading to a secondary line switch, and'should the contact 8 that is engaged lead to a busy secondary line switch a locking circuit is established for the relay LR, when it energizes, from battery through the winding of the said relay LR, its alternate contact 36, conductor 37 to the grounded contact 8. The circuit for motor magnet M is thus established from the ungrounded pole of the generator G through the winding of the magnet M, and the alternate contact 20 of relay R to ground at alternate contact 38 of relay LR. The motor magnet is thus energized to step the wipers 3, 4, 5 and 6 into connection with the next set of contacts. If this next set of contacts is busy. the wipers are stepped until an idle secondary line switch is encountered, and as soon as this takes place the locking circuit of relay LR is interrupted due to the wiper 4 A switching relay. SW is ar- 1 relay engaging an idle contact 8 leading to an idle secondary line switch. The relay LR in restoring opens the circuit of relay R, but relay R being slow to release remains operated until a substitute circuit is established for it as will now be described.

The opening of alternate contact 38 of rela LR opens the circuit of motor. magnet M t us preventing further operation of the wipers. U on the deenergization of relay LR relay 0 is energized over a circuit traced from batterythrough the alternate contact 40 of rela R, through the winding ofthe said relay 0 to round at the normal contact 35 of relay L The closin alternate contacts 32 and 33 of relay C tends the calling line to the selected second-.,

ary line switch. As soon as the relay C0 of the primary line switch B is energized a circuit for l1ne relay LR of the selected secondary line switch C is established from battery through the winding of the said relay LR normal contact 41 of relay R normal contact 42 of relay CO contact 10, wiper 6, alternate contact 32, the line conductor 2 through the substation A, back over the line conductor 1, alternate contact 33, wiper 5, contact 9 to ground at normal contact 43 of relay CO. The closing of alternate contact 44 of relay LR establishes a circuit for the relay R traced from battery through. the winding of the saidrelay R to ground at alternate contact 44 of relay LR The closing of alternate contact 45 of rela of primary line switch B, the said circuit being traced from battery through the winding of the "said relay R, alternate contact 46 of relay CO, conductor 47, the wiper 4, and bank contact 8 to ound at alternate contact 45 of relay R he energization of the relay R opens the initial energizing circuit of relay LR at contact 41 but should the test wiper 16 of the secondary line switch C be engaging a busy contact 13 a locking circuit is established for the relay LR traced from battery through the winding of the said relay LR alternate contact 48 of relay LR to the busy grounded contact 13 which leads to a busy first selector D. The relay LR and relay R are thus energized establishing an energizing circuit for the motor magnet M traced from battery through the alternate contact 49 of relay LR, alternate contact 50 of relay R and through the interrupter I to ground. The wipers 16, 17 and 18 are thus stepped from one contact to the next, by the motor magnet M until an idle first selector has been encountered. When this takes place the locking circuit for the relay LR is interrupted at the idle contact 13 which has been engaged by the test wiper 16 and the restoration of the said line relay LR opens the circuit of the motor magnet M R closes the substitute circuit forcontact 52 of relay LR.

thus preventing further stepping of the W1 ers.

he restoration of the line relay LR closes a circuit for the cut-off relay CO traced from batter through the alternate contact 51 of rela R and through the winding of the cut-0 relay CO to round at normal Ihe circuit of relay R is interrupted upon the restoration of relay LR but it being slow to release remains energized until a substitute circuit is established for it as will now be described. V

Although the opening of alternate contact 44 of relay LR? interrupts the energizing circuit for said relay R the relay R being slow to release does not immediately restore due to its slow to release action, and therefore upon the energization of relay CO the calling subscribers line is extended to the idle first selector bringing about the operation of the rimary relay PR, the circuit of said relay R being traced from ground throu h the left hand winding of the said relay R, the primary conductor P, contact 14, wiper" 17, alternate -contact 43, contact 9 and wiper 5, alternate contact 33, the line conductor 1, through the substation back over the line conductor 2, alternate contact 32, wiper 6, contact 10, alternate contact 42, wiper 18, contact 15, secondary conductor S and tllIOligh the right hand winding of the relay P to battery. Relay PR upon energizing, causes the closing of its alternate contact 53 whereby a locking circuit for relay R is established, traced from battery2 through the winding of the said relay alternate contact 54 of relay CO wiper 16, contact 13, and through the alternate contact 53 of relay PR to ground, thus maintaining the said relay R energized. This ground connection at alternate contact 53 also places a busy or ground potential upon the multiple contacts 13, thereby preventing any other secondary line switch from connecting with the selected first selector D. Also responsive to the energization of rela PR, a circuit for the main release rela hlR is established from battery through t e winding of the said relay MR, and through alternate contact 55 of relay PR to ground at normal contact 56 of the primary off-normal switch PON, rela MB is thereupon energized and establis es a substitute circuit for itself through its alternate contact 57, this circuit being provided to take the place of its initial energizing circuit which is interrupted upon the first movement of the primaryotf-nop mal switch PON. It will thus be seen that the substation now is connected to a first selector D and that relay PR is energized over a metallic circuit including the line conductors and the calling substation A.

The closing of alternate contact 53 of retends from ground at contact 53 of relay PR at the first selector through the winding of said relay 19 to battery. The last rclay of the train of relays has ground connected to its contact and upon the energization of all the relays of the series a circuit is closed for relay 22 over a circuit extending from battery through the. relay 22 and through the alternate contacts of the chain of relays to ground. There is such a relay 19 associated with each first selector of the group of first selectors associated with a group of secondary line switches. Should all of the first selectors of the group of secondary switches become busy the said ground is connected through the alternate contacts of relays 19, etc., to the relay 22 and to battery. The relay 22, upon energizing, closes its alternate contacts 23, placing ground upon all of the trunks leading from the groups of primary line switches to this group of secondary line selectors.

Assuming now that a subscriber associated with one of the primary groups having access to this secondary group initiates a call and should the subscribers primary switch be standing in connection with a trunk leading to this particular secondary group, it will find the bank contact 7 grounded and the relay LR of the said primary switch will cause the primary switch to step to the next contact. The said circuit for relay LR extends from ground at relay 22, through contact 7,rwiper 3, conductor 201, alternate contact 36 alternate contact 36, and through the winding of the relay LR to battery, thus bringing about the stepping of theprimary line switch wipers to the next set of contacts which lead to another group of secondary line switches. If the next contact 7 now engaged by the wiper 3 be idle, and should the contact 8 engaged by the test wiper 4 be idle, the relay LR w1ll be deenergized thus extending the calling line to an idle secondary line selector. But if the test wiper 4 engages a busy contact 8, or should the wiper 3 engage a busy contact 7, the wipers 3, 4, 5 and 6 are stepped to the next set of contacts. From the foregoing it is apparent that a ground from either bank contacts 7 or a ground from a bank contact 8 brings about the movement of the wipers of the primary. line switch from one contact set to the next until an idle trunk leading to an idle secondary line switch in an idle group is encountered. When this takes place the relay LR- deenergizes as before stated and extends the calling line to the idle secondary line switch.

N ow assuming that upon the initiation of a call by the calling subscriber A that both the primary line switch B and secondary line switch C wipers are resting on idle contacts leadin to an idle secondary line switch and an iille first selector, respectively, the operation of the primary and secondary switches is as follows: The subscriber upon the removal of the receiver at the calling substation A brings about the energization of the line relay LR of the primary line switch B, as previously described, and the said relay, upon energizing closes a circuit for the relay R. Relay R, upon energizing opens the circuit for relay LR and as wipers 34 are in engagement with idle contacts relay LR immediately deenergizes. The contacts 20 and 30 relay R are so adjusted that the normal contact 30 breaks before contact 20 makes, and as the relay LR is a quick-acting relay it immediately restores and opens its contact 38 before contact 20 of relay R completes the circuit for the motor magnet M. LR restoring opens the initial circuit for relay R, but a substitute circuit is established as described in the pre vious description of the operation of the circuit. Immediately upon the denergiza tion of relay LR, an energizing circuit for relay CO is established as previously traced and closes its alternate contacts 32 and 33 to extend the calling subscribers line to the secondary line switch. Upon the energization of relay C0, of primary line switch B, a circuit for the line relay LR of secondary line switch C is established, as previously traced. Relay LR upon energizing closes the circuit for relay R as before described. Immediately upon the energization of the relay R the circuit of relay LR is opened at contact 41 and the wiper 16 being on an idle contact no substitute looking circuit is established for relay LR The relay LR deenergizes due to the fact that contact 41 opens before contact 50 is closed, and therefore no circuit for motor magnet M is established.

The closure of alternate contact 45 of relay R closes a substitute circuit for relay R of the switch B. The relay R is slow to release and remains operated until a substitute circuit is established from round at the alternate contact 53 of relay RR of the first selector D. Upon the deenergization of relay LR a circuit for relay CO is established, and the closure of the alternate contacts 42 and 43 extends the circuit of the calling subscriber to the idle first selector upon which the wipers 16, 17 and 18 are resting. From theforegoing it is apparent that a subscriber may connect his line through his individual line switch and a secondary switch to a first selector switch l without moving the wipers of either switch.

The calling subscriber having seized an idle first selector switch byeither connecting them without moving either primar or secondary line switches, or by moving oth or by moving only one,.either the primary or secondary, is now read to operate his dial to call the first digit of the called number.

It will be remembered that the number as signed to the called substation F is 243. and therefore, the first act of the calling subscriber to complete the call is to operate the calling device CD to cause two interruptions of its contacts 21 which results in two deenergizations of relay PR. Although the deenergization of the relay PR causes the interruption of the circuit of main release relay MR at contact 55, relay MR being a sluggish relay does not retract its armature until a continued deenergization of relay PR is efi'ected as that of replacing the receiver upon the switch hook at the calling substation A. The said operations of relay PR which are effected by the calling device as stated will cause two current impulses to be transmitted to the rimary magnet PM and secondary relay ER over a path traced from ground at normal contact 53 through alternate contact 58 of relay MR, over conductor P, normal contact 59 of secondary off-normal springs SON to the point 60, the current dividing, one path continuing over conductor 61 and through the winding of the primary magnet PM to battery, the other ath passing through the secondary relay R to battery. Relay SR being a sluggish relay is energized responsive to the first impulses and maintains its armature attracted until the cessation of the impulses, thus maintaining its normal contact .62 interrupted during the transmission of the impulses. Two operations of magnet PM affect two primary steps of the wipers '24, 25 and 26 to the second row of contacts which are the contacts 27, 28 and 29 which lead to the connector E which is adapted to extend the connection to the called line in a well known manner. After the said two impulses have been transmitted the secondary relay SR restores, thus closing its nor mal contact 62 and as the primary oif-normal springs PON have moved to their alternate position upon the first primary ste of the wipers, the circuit for test relay T is established from ground at said normal contact 62, through alternate contact 63 of the primary off-normal springs PON, the normal contact 64 of the secondary ofl normal springs SON and through the winding of the relay TR to battery. The relay TR is thereupon energized closing its alternate contact 65 to establish an energizing circuit for secondary magnet SM whereby the wipers 24, 25 and 26 are stepped into engagement with the first set of contacts 27, 28 and 29 of the group selected.

Upon the first secondary step of the wi ers the secondary off-normal springs S N move to their alternate position and the opening of normal contact 64 interrupts the initial energizing circuit of the relay TR, but assuming that the first set of contacts 27, 28 and 29 lead to a busy connector and the test contact 27 grounded, relay TR does not deenergize as a substitute malntalning circuit is established from the said grounded contact 27, through the wiper 24, alternate contact 66 of relay TR, alternate contact 67 of relay MR, conductor 68 and through the winding of the relay TR to battery, thus maintaining the operating clrcuit for the secondary magnet SM. The magnet M is again operated to advance the wipers 24, 25 and 26 and continues to do so until an idle set of contacts is reached, and the circuit for relay TB is interrupted, thereby allowing it to deenergize and open the cir cuit of magnet SM. Upon the deenergization of relay TR ground is connected to the multiple contacts 27 from normal contact 66, thereby rendering the selected set of contacts, 27, 28 and 29 busy and preventing any other switch from connecting thereto. The closing of normal contact 66 of relay TR establishes a circuit for the relay 70 of the connector switch E traced from batte through the winding of the said relay 70, the normal contact 71 of release relay BB contact 27 and wiper 24 to ground at normal contact 66. The'operation of the relay 70 at this time is only incidental.

The subscriber at the calling substation A now actuates his calling device to transmit four impulses of current which brings about four denergizations of the primary relay PR. Four denergizations of the relay PR bring about the operation of the primary magnet PM and the secondary relay SR of the connector switch E, the circuit thereof'being traced from ground to normal contact 53, alternate contact 58 of relay MR, conductor-P, normal contact 72 of relay TR, wiper 25, contact28, conductor P normal contact 73 of relay 110, conductor 74, normal contact 75 of the secondary off-normal springs SON to the point 7 6, the current dividing, one path continuing to the normally closed contact 77 of theswitching re lay SW and through the winding of the primary magnet PM to battery, the other path continuing from point 76 through the winding of secondary relay SR to battery and ground. Responsive to the first impulse,

the secondary relay SR is energized and being 'a sluggish relay maintains its arma ture attracted. until thecessation of the fourimpulses. The four impulses of current flowing through the magnetPM causes four.

operations of the said primary magnet PM and effects four primary steps of the

wipers

77, 78 and 79 to the fourth row of contacts rent dividin which includes contacts 80, 81 and 82, this row of contacts including the terminals of the line of the called substation F. Following the cessation of the said four impulses, secondary relay SR denergizes closing a path for current through the switching relay SW the circuit being traced from battery through the winding of the relay SW normal contact 83 of switching relay SW the normal contact 84 of the relay SE to ground at alternate contact 85 of the pri mary off-normal contact PON. The relay SW upon energizing, closes a locking circuit for itself established throughits alternate contact 83. over the conductor 86 to the grounded private conductor 87. The opera tion of relay SW disconnects the primary magnet PM and connects secondary magnet SM in circuit with the conductor P to take the next set of impulses. The calling subscriber now actuates the calling device CD to effect three interruptions of the calling device springs 21 thereby causin three operations of the primary relay P Responsive to these three operations three impulses of current are transmitted through the secondary relay SR and secondary magnet SM traced from ground at normal contact 53 of relay PR over the previously traced ath over conductor P to normal contact 3, conductor 74, normal contact 75 to the point 7 6, the circuit dividing, one path continuing through alternate contact 77 of relay SW normal contact 88 of release relay RR through the winding of the magnet 'SM and normal contact 89 to battery and ground. The other path of current continues from the point 76 through the winding of the relay SR to battery. Relay SR is energized upon the first impulse closing its alternate contact 90. Upon the first secondary step of the switch the secondary olfnormal switch contacts SON are moved to their alternate position, and the contact 75 assumes its alternate position thereby interrupting the initial path for the current imulses through the said normal contact 75. owever, a new ath for impulses flowing through magnet M is provided, extending from conductor 74, through alternate contact 90 of relay SR to the point 76, the curpart passing through alternate contact 7 of SW to normalcontact 88 and through the winding of magnet SM? to battery and ground at normal contact 89, and part passing through relay SR to battery. The result of these three impulses of current is that magnet S'M. steps wipers 77, 7 8 and 79 into engagement with the desired set of contacts 80, 81 and 82 which are the con- 12 tacts connected with the called subscribers line. Following the last impulse relay SR de'nergizes closing its normal contact 91 thereby connecting the upperwinding of the line test relay LT-tothe terminal 80 of the 30 calied line for the purpose of testing said iine for its idle or busv condition.

to this period in the operation of the system, the operation is the same whether connecting to an idle or busy line. Assuming that the called line is idle, a path for current through the upper Winding of relay LT is provided by the closing of normal contact 91, the circuit being traced from ground at normal contact 92 of relay 93, through the alternate contact 94 of relay 70, the normal contact 91 of relay SR through the 'upper winding of the relay LT, the conductor 95, the wiper 77, contact 80, and throu%h the winding of the relay (:0 of switch 1 to battery and ground at normal contact 40 of relay R The relay LT upon energizing closes a locking circuit for itself through its alternate contact 96, over a circuit traced from battery through the alternate contact 97 of relay 70, the lower winding of the rela LT, the alternate contact 96 of relay L conductor 197, alternate contact 94 of relay 70, and the normal contact 92 of relay 93 to ground. The closing of alternate contact 100 of relay LT shunts its upper winding and places a direct ground from the conductor 197 through alternate contact 100, over conductor 95, to test wiper 77 maintaining the relay c0 energized and also preventing any other connector switch from establishing connection with the terminals of the called line F. The closing of alternate contact 101 of the relay LT establishes an energizing circuit for the relay 102 traced from battery through the winding of relay 102, the alternate contact 101 of said relay LT to ground at normal contact 92, bringing about the energization of the said relay thereby interrupting its normal contact 103 to disconnect the busy back apparatus BB from the secondary conductor S The closing of

contacts

104 and 105 of relay 102 connects battery and ground to the termi-- nals of the ringing control relay RC. Also upon the energization of the relay LT an energizing circuit for the ringing interrupter relay R1 is established, the circuit being traced from battery through the normal contact 106 of relay 93, the alternate contact 107 of relay LT and through the windin of the relay RI through the interrupter to ground. The relay R1 is thus intermittently energized and denergized to connect ringing generator G with the terminals of the called line, the path of the ringing current being traced from the ungrounded pole of the generator G through alternate contact 108 of relay R1, the wiper 78, bank contact 81, through the condenser and call bell of the called substation F, back through bank contact 82, wiper 79 to the grounded pole of the generator Gr through the alternate contact 109 of the '7, II relay RT. The bell of the called substation F is thus intermittently rung, and upon the response of the called subscriber at the substation F a circuit for the ringing control relay RC is established, traced from ground through the alternate contact 104, the upper Winding of the relay RC, the normal contact-108 of relay RI (when relay R1 is in its deenergized position), the wiper 78, contact 81 through the now closed contacts of the substation switch hook back through contact 82, wiper 79, normal contact 109, through the lower winding of the relay RC, and alternate contact 105 to battery at alternate contact 97 of relay 70.

Upon the energization of relay RC an energlzing circuit for the relay 110 is closed, sald circuit being traced from battery through the winding of the said relay 110 to ground at alternate contact 111 of the relay RC. The closing of alternate c011- tact 112 of relay 110 establishes an energizlng circuit for the relay 93, said,circuit being traced from battery through the alternate contact 112 of relay 110, through the winding of the relay 93, the conductor 113, to ground at alternate contact 85 of the primary off-normal springs PON. The relay 93, upon energizin closes a locking circuit for itself traced from battery through its alternate contact 106 and through the winding of the said relay 93 to ground at contact 85 of the primary off normal springs PON The opening of normal contact 106 interrupts the circuit of the relay RI thus preventing further application of ringing current. The energization of the relay 110 brings about the closing of contacts 73 and 114 which establishes the continuity of the talking conductors to the called subscriber 105 at substation F. The talking circuit between the calling subscriber A and the called subscriber F may now be traced over the heavily marked conductors, the said conductors having the condensers K at K interposed at the first selector D.

After the subscribers have finished conversation, they may cause the restoration of the switches used in establishing the connection, the calling subscriber A controlling the 115 r estoration of the first selector D, while the subscriber at the called substation F controls the restoration of the connector switch E. Assuming that the subscriber at A is first to replace his receiver upon the switch hook, the circuit of the primary relay PR is interrupted causing the restoration of the said rela and bringing about the interruption oft e alternate contact 55 allowing the deenergization of the main release relay MR. Thedeenergization of the main release relay MR establishes a circuit for the test relay TR effecting the restoration of the switch D in the following manner. The circuit of relay TR established by the deener- I gization of the relay MB- is traced from ground at normal contact 62 of relay SR, alternate contact 63 of the primary oif-normal springs PON to conductor 120, the normal contact 67 of relay MR, the conductor 68 and through the windin of the relay TR to battery. Following t e energization of the relay TR, the circuit is a-galn closed for the secondary magnet SM due to the closure of alternate contact 65. The wipers 24, 25 and 26 are step d ahead by the operation of the magnet M until they have passed one ste beyond the last contact set in the row. llpon reachin this position, a release pawl is automatical y tripped whereby the wipers restore from their PIlma ry ad'ustment by a spring whereby switch P( N is restored interrupting its alternate contact 56 to effect the restoration of the switch D from its secondary adjustment as will be described. Upon the wipers being restored from their primary adjustment, a second pawl is tripped whereby they are restored by a spring from their secondary adjustment to normal causing the restoration of the switch SON.

It will be noted that while wipers 24, 25 and 26 are being adjusted to their normal position, the line conductors are open at

normal contacts

72 and 72 thus preventing interference with any existing connections. When the wipers restore from their primary ad'ustment, the primary off-normal springs PN restore bringing about the opening of the off-normal contact 63 thus interrupting the circuit of relay TR which restores. As soon as alternate contact 56 of switch PON is interru ted as stated, the locking circuit for relay T1 of the secondary line switch C is interrupted as it will be remembered that relay R has been maintained energized by current flowing over the test conductor to the grounded alternate contact 56. Therefore, relay R restores opening its alternate contact 51 thus interrupting the circuit of the relay G0 which is deenergized and switch 0 is again available for use in establishing other connections. The opening of alternate contact 45 of relay R of secondary switch C brings about the restoration of the relay R of primary switch 'B and the o ening of alternate contact' lO of the relay opens the circuit of the relay C0 of primary switch B, permitting the relay CO to restore, the .switch C being again available for use in establishing other connections.

To release the connector switch E, the subscriber at the substation F restores his receiver whereby the circuit for ringing control relay RC is interrupted causing its deenergization. Its contact 121 is therefore interrupted, disconnecting ground from the conductor 122 thereby interrupting the circuits for relay 102 and LT of. connector E,

aiid relay 00 of the primary selector B associated with the called substation F causing their restoration. The restoration of the cut-off relay c0 restores the substation control of the. primary line switch B Also, upon the deenergizatlon of relay RC, its alternate contact 111 is interrupted, allowing the restoration of rela 110 whereby a circuit for release relay R 1 is established from battery at normal contact 112, alternate contact 123 of relay 93 through the winding of from said generator to advance

wipers

77, 78

and 79 beyond the last contact in the row whereby they are automatically restored by spring tension as in the case of the first selector. Upon retraction of the primary ofi'-' normal springs PON, the circuit of relays 93, RR, and SW are interrupted causing their restoration. The switch E now being at normal is available for use in establishing other connections.

Assuming now that the called line is busy, the operation of the system will proceed as previously described up to the final deenergization of the secondary relay SE of the connector switch E. It will be remembered that at the final deenergization of relay SR after the wipers have connected to the terminals of line F, relays SW and 7 0 are in an energized condition. Therefore, upon the denergization of relay SR the upper winding of relay LT is connected in circuit with the test wiper 77 of the test contact 80 of the called line as before.

Assuming the line F busy as a calling line, its test contact 80 is on open circuit as relay R is energized or if the line F is busy as a called line, its test contacts are con- .nected to ground back over conductor 95 as previously described. I Therefore, when the upper winding of relay LT is connected in circuit with the test contact 80, there will be no energizing circuit for the said winding as its left hand terminal is connected to ground at normal contact 92 and there will be no flow of battery and therefore relay LT does not energize. Relay LT failing to energize, neither relays 102 nor R1 are energized so that the busy back signal BB remains in connection with the secondary conductor S through'alternate contact 130 of the switch SON and normal contact 103 of relay 102 to the heavily marked'conductor over line conductor- 2, through the receiver of the substation returning over line con ductor 1 and overthe heavily marked rimary conductor P to the left hand win ing of the-.relay PR. of the first selector D to -ground. The subscriber upon replacing hisreceiver upon the switch hook causes the restoration of theapparatus used in establishing the connection in the following manner.

Due to the replacing of the receiver at substation A, the circuit of relay PR is interrupted causing itsdeenergization followed by the deenergization of the main release relayMR thereb causin the restoration of-the switch D ollowed y the restoration of the switches C and'B as previously described. It will be remembered in a previously described connection that the connector .E is restored by the subscriber at the callecl'sub-station F, but in this instance its restoration is controlled by the calling subscriber. It will be remembered that relays and SW are theonly relays energized in switch E, in this instance being locked up'over a circuit including test conductor 87 and the ound at normal contact 66 of relay TR of selector D. Therefore, upon the energization of relay TR and the restoration of switch D as described, its normal contacts 66 being'interrupted, relays 70 and SW are deenergized. Following the deenergization of relay 70, a circuit for release relay BB is established from ground at alternate contact of PON through the winding of said relay RR, normal contacts 123 and 97 to battery. Relay RR, upon energizing, closes its contact 71 connecting ground to its test conductor 87 and contacts 27, preventing any other switch from making connection with connector E during its release. Although relay SW deenergizes as just stated at the time its en ergizing circuit is interrupted at relay TR it immediately energizes again upon the closing of its normal contact 83 due to the main connection for PON and is again locked up through its alternate contact 83 to ground at alternate contact 71, remaining so until the restoration of PON Returning now to relay RR the closing of its

alternate contacts

88 and 89 causes the releasing operation of magnet SM as previously described whereby switch F is restored to normal causing the restoration of the primary off normal contacts PON and relays RR and SW Switch E is now at normal and available for use in establishing other connections.

Havin given the description of the operation of t e system in extending a call from a calling substation to a called substation, I will now describe one method which may be employed in distributing the trunks beswitches.

,ary selectors.

tween the rimary and secondary, line switches. owever, it is to be understood the primary and secondary trunks are applicable to m invention, one method being shown for i1 ustrative purposes only. The primary line switches are arranged in ondary line switches are also divided into ten groups In Fig. 4 I illustrate dia ammatlcally two groups B and B of pnmary switches, each group containing 1,000 line This illustration is made on the basis of three equals ten. That is ten line switches are shown by three smal and three groups of three small circles equal ten times ten or one hundred line switches and so on. At T and T I show two groups of primary trunks, each group comprising 1 circles,

that various other methods of distributing v three groups of ten trunks, that is one hundred trunks each trunk leading to three groups C, d and C" of secondary switches, each group of secondary switches compris 111g two groups of ten each of said secondary line switches, making twenty secondary line switches in a group for each of the tengroups of secondary line switches. With each of these three groups of secondary switches, I show a group of first selectors D, D and D,- each group comprising ten first selectors. As herein shown, the first trunk of the first primary group leads to the first switch of the first secondary group, the second trunk of the first primary group leads to the first secondar switch of the second secondary group an the third trunk of the first primary group leads to the first secondary switch of the third secondary group, etc., for the ten trunks. The first trunk of the second hundred primary switches in the first group B leads to the second secondary switch of the first secondary grou and the second trunk of the second hun red group of the first grou B leads to the second secondary switch and so on. The first trunk associated with the first one hundred primary switches of the second group B leads to the eleventh secondary switch of the first group of second- It is thought that the scheme of trunking of the diagram as illustrated in Fig. 4 may be readily followed out from the above description. It may also be readily seen that a method of ten per cent. trunking is maintained, and in the above description the trunks of each group of one hundred subscribers have access to one hundred first selectors making a system of this kind more flexible and distributing the load among all of the one hundred first selectors. Should all of the selectors of the first group D be busy, the train of

relays

19, 19 etc., associated with this first group D would operate to energize relay 22, as previously described, and all of the idle trunks leading to the first group C of secondary selectors would be made busy.

While I have ilustrated my invention operating in connection with a certain form of selector and connector, it is to be understood that my invention is readily adaptable to other systems and that changes and modifications may readily suggest themselves, and I therefore do not wish to be limited to the exact structure and method of trunking as illustrated, but aim to cover all such changes and modifications which come within the spirit and scope of the'appended claims.

What I claim as new and desire to secure by United States Letters Patent is:

1. A telephone system including groups of primary switches, secondary switches accessible to said primary switches and divlded into groups, said primary and secondary switches being provided with contact makers adapted to remain in their antecedent progressive positions, a group of first selector switches for each group of secondary switches, and means for preventing any primary switch from connecting to an idle secondary switch in a group where all the first selector switches are busy.

2. A telephone system including a sub- 'scribers telephone line, a first selector switch, a secondary progressively movable non-restoring trunk.selecting rotary switch provided with an individual driving magnet and wipers for directly connecting to a trunk leading to said first selector switch, a primary progressively movable non-restoring trunk selecting rotary switch provided with an individual driving magnet and with wipers for directly connecting said calling subscribers line to a trunk extending to said secondary switch, said switches being arranged to directly connect the calling subscriber to the first selector switch without moving said switch wipers if said switches are idle at the time the calling subscriber initiates a call, and means for afterward operating said first selector switch in accordance with the first digit of the called number.

3. A telephone system including subscribers telephone lines, a first selector switch, a secondary non-restoring automatic trunk selecting switch provided with wipers for directly connecting to a trunk leading to said first selector switch, a primary nonnumerical automatic trunk selecting switch provided with wipers for directly connecting a calling one of said subscribers lines to said secondary switch, said switches being adapted to remain in their antecedent progressive positions at the time of release and to extend connections without moving their wipers if said wipers are in engagement with idle contacts, and substation-controlled means for operating said first selector switch in accordance with a digit of the called number to extend a connection in the direction of the called subscriber.

41-. A telephone system including subscribers telephone lines. non-restoring rotary trunk selecting primary switches, non-restoring rotary trunk selecting secondary switches, contact makers for each of said primary switches normally in engagement with the last secondary switch used, contact makers for each of said secondary switches normally in engagement with the last first selector switch used, first selector switches, operating mechanism for said rotary switches, and substation controlled means for operating the'mechanisms of said primary and secondary rotary switches to connect idle first selectors with calling lines, said actuations of the switches to connect calling lines with first selector switches being established Without operating the motor magnets of the primary and secondary switches if the wipers of the same are in engagement with idle trunks.

5. A telephone system including subscribers telephone lines, non-restoring r0- tary primary switches, non-restoring rotary secondary switches, contact makers for said primary switches normally in engagement with the last secondary switches used, contact makers for said secondary switches normally in engagement with the last first selector used, first selector switches, operating mechanism for said rotary switches, substation controlled means for operating the mechanisms of said primary and secondary rotary switches toconnect idle first selectors with calling lines, said connections being eilected without operating the motor mechanism of the primary-and secondary switches if the wipers of the primary and secondary switches are in engagement with. idle trunks at the time that calls are initiated, and means for disassociating said calling subscribers lines and said first selector switches while maintaining said rotary switches in their antecedent progressive positions.

6. A telephone system including subscribers telephone lines, a first selector switch, a secondary non-numerical non-restoring trunking switch having movable contact makers normally in engagement with a trunk directly connected to said first selector switch, a primary non-restoring non-numerical trunking switch having contact makers directly in connection with a trunk leading to said secondary switch, said primary and secondary switches being for use in efi'ecting connection between a calling one of said lines and said first selector switch, and means controlled by the removal of the receiver at the substation of said calling line for effecting said connection while maintaining said non-numerical switches in their antecedent progressive positions, without moving the contact makers of sald trun ing switches, 1

7. A telephone system including a subscribers telephone'line, an individual switch for said line, secondary switches accessible to said individual switch, first selector switches accessible to said secondary switches, trunks inter-connecting said individual and said secondary switches, contact makers for said individual switch normally in engagement with its bank contacts connected to said secondar switches, contact makers for said secon aryswitches normally in engagement with bank contacts connected direct y to said first selector switches, trunks interconnecting said secondary and said first selector switches, and means controlled over the calling subscribers line for operating said individual switch and an idle one 0 said secondary switches to extend a connection to .an idle first selector switch while maintaining said individual and secondary switches in their antecedent progressive positions if they are in connection with idle trunks.

87in automatie progressively movable switch, a pair of test wipers for said switch, banks of coiiperating contacts for cooperation with said wipers, a control relay for said switch, means for energizing said relay, and means controlled by said test contacts and wipers to maintain the said control relay in energized position if either of said wipers are inengagement with busy contacts. p

9. An automatic progressively movable trunk selecting switch, a pair of test wipers for said switch, coiiperating bank contacts for said wipers, a control relay, means for energizing said control relay, and means for maintaining said relay energized as long as either of said wipers engages busy bank contacts.

10. A telephone system including subscribers telephone lines, groups of primary rotary non-restoring switches for said subscribers lines, contact makers for said primary switches adapted to always be rotated in the same direction, secondary rotary nonrestoring switches accessible to said primary rotary switches, a group of first selector switches for each group of secondary switches, and means for preventing a primary switch from connecting to an idle secondary switch in a group where all the first selector switches are busy.

11. A telephone system including subscribers telephone lines divided into groups, individual rotary non-restoring switches di vided into groups corresponding to the groups of subscribers lines, groups of secondary switches accessible to said individual switches, contact makers for said secondar switches adapted to always be rotated in the same direction, a group oi first selector switches for each group of secondary switches, said first selector switches of any group being less in number than the number of secondary switches in a group,and means for preventing, a primary switch fromconnecting to an idle secondary switch in a said primary and secondary switches adapt-- ed to always rotate in the same direction, a numerical switch, means controlled by the calling subscriber for connecting to said numerical switch via said primary and secondary switches, and substation controlled means for operatin said numerical switch in accordance with t e first digit of the called number to extend the connection in the direction of the called line. i

13. A telephone system including a calling subscribers line, a first selector switch, a secondary trunk selecting switch having its wipers normally in engagement with a trunk extending to said first selector switch, a primary switch having its wipers normally in engagement with a trunk extending to said secondary switch, meansfor connecting said calling subscribers line to said first selector switch via said primary and secondary switches while maintaining the wipers of said primary and secondary switches in connection with said trunks, and means -for disconnecting said calling line from said first selector switch while maintaining said primary and secondary switches in their antecedent positions.

14. A telephone system including subscribers telephone lines divided into groups, primary switches likewise divided into groups and individual to the subscribers lines, secondary switches divided into groups, contact makers for said primar switches always in engagement with secon ary switches, a group of' first selector switches for each group of secondary switches, and means common to a group of first selector switches for rendering busy all idle secondary switches associated with said group of first selector switches when said rst selector switches all become busy.

15. A telephone system including primary switches divided 1nto groups, secondary switches divided into groups and accessible to said primary switches, a group of first selector switches for each group of secondary switches, contact makers for said secondary switches always in engagement with said first selector switches, means for including all the first selector switchesin one group in conversational circuits, and means for preventing primary switches from connectin with any idle secondary switch associate with said group of first selector switches.

16. An automatic switch having a pair of test wipers and a pair of line wipers, cooperating contacts or said wipers, a relay individual to said sw1tch,-means for energizing said relay, and means for maintaining said relay energized as long as either of said test wipers engages busy bank contacts.

17. A telephone system includ ng a subscribers line, an automatic swltch individual thereto passive ank contacts for said test wipers a test relay for said switch, and means or maintaining said relay in its operative pos1- tion as long as either of said wipers engages busy passive contactsr vl8. A telephone system including a subscribers telephone line provided w1th an individual rimary switch, a secondary trunking swltch having only three movable contact makers accessible to said prlmary switch, a first selector switch accessible to.

said secondary switch, bank contacts for said secondary switch having conductors connected thereto and directly extending tosaid first selector switch, and subscriber controlled means for extending a connection through said primary and secondary switches to said first selector switch without moving the wipers of said primary and secondary switches.

19. A telephone s stem includlng a subscribers telephone ine, a trunk selecting switch individual thereto, a secondary trunk selecting switch, having only three contact makers, bank contacts for -said secondary trunk selectin switch, a first selector switch, trunk con uctors connecting the bank contacts of the secondary switch directly to said first selector switch, movable contact wipers for said individual switch, means for extending a connection from said subscribers line through said individual and secondary switches to said first selector switch, and means for releasing said connection without alterin the antecedent progressive positions 0? said individual and secondary switches.

20. A telephone system including a sub-. scribers telephone line, a trunk selecting switch individual thereto, a secondary trunk selecting switch provided with only three contact wipers, a air of talking wipers and a test wi er, a rst selector switch, bank contacts or said secondary trunk selecting switch conductors extendin directly from said bank contacts to sai first selector switch, individual contact wipers for said individual switch, means for extending a connection from said subscribers line through said individual and secondary switches to said first selector switch, means for releasing said connection, and means for reestab- Erovided with a pair of test wipers,

lishing said connection without moving the wipers of said individual and seconda swltches.

of primary switches, secondary switches divided into groups accessible to said primary switches, contact makers. for saidprimary switches always in engagement with secondary switches, a group of first selector switches associated with each group of secondar switches, contact makers for said secon ary switches always in engagement with the first selector switches, and means for reventing any one of said primary switc es from connecting to a secondary switch in a group associated with a group of busy first selectors.

. 22. A telephone system including subscribers telephone lines, non-restoring rotary primary switches, non-restoring rotary trunk selecting secondary switches, trunks leading from the banks of the primary switches directly to the said secondary switches, connective links, trunks leading directly from the banks of the secondary switches to said connective links, individual operating mechanism for said rotary switches," substation. controlled means for operating the mechanisms of said primary and secondary rotary switches to connect idle connective links with calling lines, means for disassociating said cal-ling subscribers lines and 'said connective links while maintaining said rotary switches in their antecedent progressive positions and without actuating said operating mechanism, said switches now being effective to extend other connections from the calling lines to theconnective links without actuating the operating mechanism of the switches whereby said connections are completed without moving the active contacts of the rotary switches.

23. A telephone system including groups .of primary trunks selecting non-numerical progressively movable switches of the nonrestoring type adapted to remain in their antecedent progressive positions, secondary trunk selecting progressively movable non-numerical switches accessible to said primary switches divided into groups, a group of first selector switches for each group of secondary switches, trunks leading directly from the banks of the secondary switches to said first selector switches, and means for preventing any primary switch 21. A telephone system including a. group from connecting to an idle secondary switch aeaasvl numerical switches, means controlled by the removal of the receiver at the substation of said calling line for effecting said connection while maintaining said non-numerical switches in their antecedent progressive positions, and means for disconnecting said line from said connecting link while maintaining said contact makersin their selective positions.

25. A telephone system including a group of primary switches, secondary switches of the non-restoring type adapted to remain in their antecedent progressive positions and divided into groups accessible to said primary switches, a group of first selector switches associated with each group of secondary switches, and means for preventing any of said primary switches from connecting to a secondary switch in a group of secondary switches where all the first selector switches associated therewith are busy.

26. A telephone system including a calling subscribers line provided with an individual non-numerical trunk selecting rotary switch, a secondary non-numerical trunk selectin rotary switch accessible to said indi- 'vidua rotary switch, motor mechanism for each of said switches, a connective link, trunk conductors extending directly from said connective link to bank contacts of said secondary switch, and means under the control of the calling subscriber for operating the individual motor mechanisms of said rotary switches to operatively connect the calling line with said connective link, said switches being operative to extend a second connection from said calling line to said connective link without operating the motor mechanisms of the switches if said switches are on idle contacts when the second connection is efiected.

27. A telephone system including a calling subscribers line, an automatic non-numerical trunk selecting switch individual thereto, a secondary automatic non-numerical trunk selectin switch accessible to said first automatic switch, motor mechanism for each of said switches, a connective link, conductors extending directly from the bank of said secondary switch to said connective link, means responsive to the removal of.

the receiver at the calling substation to connect said connective link with said calling line via said rotary switches without operating the motor mechanisms of said rotary switches, and means for extending a connection from said connective link to a called subscribers line, thereby completing a talking connection involving the said primary nd secondary switches and the said connective link.

128. A telephone system including subscribers telephone lines, non-restoring primary rotary trunk selecting switches, nonrestoring secondary rotary trunk selecting switches, connecting circuits, trunk connections extending directly from the banks of the rotary switches to, the connecting circuits, individual operating mechanisms for said switches, substation controlled means for operating the mechanisms of said primary and secondary switches to connect idle connecting circuits with calling lines and for disconnecting subscribers lines from said connecting circuits without operating sa d operating mechanisms, said switches being operable to now extend other connections from calling lines to idle connected circuits without operatin the mechanism of the switches, and means or completing connections from said connecting circults to called subscribers lines, said connections includlng primary and secondary trunking switches and one of said connecting circuits.

29. A telephone system including a calling subscribers line, a connective link, a secondary trunk selecting non-numerical switch having its wipers normally in engagement with a trunk extending to said connective link, a primary trunk selecting non-numerical switch having its wipers normally in engagement with a trunk extending to said secondary switch, means for connecting said calling subscribers line to said connective link via said primary and secondary switches while maintaining the wipers of said primary and secondary switches in connection with said trunks, and means for extending a connection from the connective link to a called subscribers line, the completed connection includin the primary irndr secondary switches and t e connective 30. A telephone system including subscribers telephone lines, groups'of primary non-restoring switches for said subscribers" lines provided with individual motor mechanisms, secondary non-restoring switches accessible to said primary switches, a group of connective links for each group of secondary switches, and means for preventing a primary switch from connecting to an idle secondary switch in a group where all the connective links are busy. 1

31. A telephone system including a group of primary switches, secondary switches di-' said connective link via said primary and secondary switches while maintaining the wipers of said primary and secondary switches in connection with said trunks, means for disconnecting said calling line from said connective link while maintaining said primary and secondary switches in their antecedent positions, and means for completing a talking connection between said calling subscribers line and a called subscribers line, said talking connection when completed including said connective link and said primary and secondary trunking switches.

33. A telephone system including a subscribers telephone line, connective links, primary and secondary rotary switches for connecting said calling line to an idle connective link, said primary and secondary switches being of the non-restoring type and provided with movable contact makers to always rotate in the same dlrection, and substation controlled means for connecting said calling line to an idle one of said connective links and for operating the switch adjusting mechanisms of said primary and secondary switches only if the trunks that they are in connection with are busy.

34. A telephone system including a 'subscribers telephone line, an individual nonnumerical trunking switch for said line, secondary switches accessible to said individual switch, connective links accessible to said secondary switches, trunks interconnecting said individual and said secondary switches, trunks interconnecting said secondary switches and said connective links, means controlled over the calling subscribers line for operating said individual switch and an idle one of said secondary switches to extend a connection to an idle connective link while maintaining contact makers of said individual and secondary switches in their antecedent progressive positions if they are in connection with idle trunks, and means for directly extending the talking connection from an idle connective link to a called subscribers line.

35. A telephone system including primary switches divided into groups, secondary switches divided into groups and accessible to said primary switches, individual stepby-step motor mechanism for each of said primary and secondary switches, a group of connective links for each group of secondary switches, means for including all of the connective links in one of said groups in conversational circuits, and means for preventing primary switches from connecting with secondary switches associated with said engages busy bank contacts.

37. A telephone system including an automatic switch provided with a line wiper and with a pair of test wipers, individual motor mechanism for said switch, cooperating bank contacts for said wipers, test, means for said switch, means for operating said testmeans and for maintaining said test means operated as long as either of said test wipers engages busy bank contacts.

38. A telephone system including a subscribers telephone line, connective links, primary and secondary non-restoring trunk selecting switches for connecting said telephone line to an idle one of said connective links, contact makers for said switches, trunks extending directly from the bank of the primary switch to the secondary switch and from the bank of the secondary switch to the said connective links, substation controlled means for disconnecting said subscribers line from said connective link while maintaining the contact makers of said switches in their antecedent progressive positions, and means for completing talkingconnections from the calling telephone line through the primary and secondary trunking switches and the selected connective link to a called subscribers line, said completed connection including the idle connective link, and subscriber-controlled means for releasing the idle connective link.

39. A telephone system including a subscribers telephone line provided with an individual non-numerical trunk selecting primary switch, a non-numerical secondary trunking switch accessible to said primary switch, a connecting linkaccessible to said secondary switch, a trunk extending directly from the bank of the secondary switch to the connecting link, subscriber controlled means for extending a connection through said primary and secondary switches to said connecting link without moving the wipers of said primary and secondary switches, means for extending a connection directly from the connecting link to a called subscribers line, and subscriber-controlled means for disconnecting the connecting link from the called subscribers line.

40. A telephone system including a subscribers line, a link circuit, a primary and a secondary non-numerical trunk selectin switch for extending connection from sai line to said link circuit, a trunk extending directly from said primary to said secondary swltch and a second trunk extending directly from the bank of said secondary switch to said link circuit, movable contact makers for each of said switches, subscribercontrolled means for connecting said line to said link circuit without moving the contact makers of said switches, means for completing a talking connection with a called subscribers line, and subscriber-controlled ,means for disconnecting the link circuit from the called subscribers line.

Signed by me at Chicago, county of Cook and State of Illinois, in the presence of two witnesses.

GEORGE A. YANOCHOWSKI.

Witnesses:

MARIE F. O. BREEN, M. R. Roonronn.