US1694623A - Telephone system - Google Patents

Description

Dec. 1l, 1928.

J. E. OSTLINE TELEPHONE SYSTEM Original Filed Dec. 5l, 1924 2 Sheets-Sheet 1 Imran D1"- Jnhn E. lme

HIT:

Dec. 11, 1928.

J. E. OSTLINE TELEPHONE SYSTEM Original Filed Dec. 31, 1924 2 Sheets-Sheet 2 Patented Dec. 1l, 1928.

I lUNITED STATES PATENT OFFICE.

JOHN E. OS'JYJLINE,y D13-LIVERPOOL, ENGLAND, ASSIGNOR, :BY MESNE ASSIGNMENTS, TO

AUTOMATIC ELECTRIC INC., OF'CHICAGO, ILLINOIS, A CORPORATION 0F DELA- WARE.

Application led December 31, 1924, Serial No. 758,998, and in Great Britain January 24, 1924. Renewed May 3, 1928.

The present invention relates to improvements in automatic or semi-automatic telephone systems and more particularly 'concerns an improvement in circuits of switches 5 of the type known as rotary connectors Such switches are provided for the purpose of establishing connect-ions to an idle line of a group of lines which are all allotted the same number in the directory. The switches used are of the two directional type having ten levels of ten sets of contacts in the level. The contacts in a level may be arranged in onetwo,`three or more groups, depending upon the size of the groups in question. Now

for n'ght service it is often desirable to have an attendants telephone connected to one line only and for this purpose a special number is allotted in the directory which is different from the number allotted for day service. The number allotted for day service corresponds to that of the first line of the group, while that allotted for night service corresponds to some number other than that of the first and it is desirable that when the number of the first group is called, if the first l'ne is busy, the switch should automatically rotate and come 4to rest on the first idle lline of a group and further that it should stop when the last line is reached and give thebusy signal if all the lines in a group are-busy, while if the night number is called then, if the night number is/busy, the busy signal is given immediately and no hunting takes place over the remaining ylines of a group. Various arrangements have been proposed for bringing about the above result which have necessitated special construction cf switch banks or have limited the grouping so that the grouping on diiicrent levels must be the same. l

It is the object of lthe presentinvention to evolve a rotary connector for bringing about the above result, which is of the same construction as that used when night service r facilities are not provided, the only alteratact of a group is connected up in one way, the second and intermediate contacts of a group are connected up .in another, while the last contact of the group is connected up in vet a third way.

More specifically avrelay controlling the automatic hunting circuit is adapted to be energized from a source of current over two test wipersupon the termination of the final series of impulses whenever the first line of a group is dialled and found busy. A terminal block having special termz'nalsadapted to be connected to an additional set of contacts in the connector switch is arranged intermediate to the other sets of contacts so that the special terminals may be`connected by a strip to one or other of the other set of contacts or left disconnected to enable the movement of the. switch to be controlled in the desired manner. The auxiliary test bank contacts in the first lne of a group are connected to battery, the auxiliary and normal test bank contacts are connected together, while the auxiliary test bank contacts of the last line of the group and of the individual lines are left disconnected.

A further` object of the invention is to reduce the number of relays in the switch and to this end the relay employed for transferring the impulsing crcuit from the primary magnet to the secondary magnet is also adapted to function as a stepping relay for controlling the automat-ic operation of the secondary magnet when the first line of a group is dialled by a calling party.,y

Another object of the invention is to connect a busy tone current and a signalling current to the calling line when all lines of a group or the line dialled .are busy-so that if the call originates from an automatic exchange the calling party'will receive a busy tone, while if the call originates from a manual exchange the operator will receive an iiio5 termittent visual signal.

In order that the invention may be clearly understood and readily carried into effect a connector or final selector switch inv accordance with the invention will now be more fully described with reference to the annexed drawings which is a diagram of connections' of two forms of the invention.

In the drawings, Figs. 1 and 3 show circuit connections of the improved connector or final selector while Figs. 2 and 4 show the special terminal blocks.

The apparatus having been described more or less in general, a detailed description of the operation of the apparatus shown in Figs. 1 and 2 will now be `given. For this pur ose, it Will be assumed that an automatic su scriber desires to obtain connection with a subscriber in a private branch exchange served by a group of trunk lines. The customary subscribers substation, individual line switch, and selector switches as used by an automatic subscriber in completing a connection are well understood by those skilled in the art and form no part of the present invention. It will therefore sufiice to say that in response to the removal of the receiver by the, calling subscriber, his individual line switch seizes an idle trunk line leading to an idle selector switch, and in response to the operations of the subscribers calling device, the selector switches are operated to select an idle trunk line leading to a connector switch.

Let us assume that the calling subscriber has established his connection as far as the last selector, and that the selector has come to rest on bank contacts connected to the conductors 20, 21 and 22of the connector switch shown in Fig. 11, this being the first idle connector accessible to the said selector. When the selector switch comes to rest upon the contacts associated with conductors 20, 21, and 22, the switching relay of the selector completesan energizing circuit for the line relay 4 of the connector switch as follows: from earth by way of lower winding of ,line relay 4, normally closed springs controlled by armature 31 of relay 3, conductor 21, over the intervening switches and the subscribers loop back to conductor 20, normally closedsprings controlled by armature 30, and through the u per winding of line relay 4 to battery. elay 4 atfarmature 33 and its working contact completes an energizing circuit for slow-to-release relay 5. Relay 5, upon energizing, connects earth to the release trunk conductor 22 at armature 34 and its working contact. This earth completes a holding circuit for the switches preceding the connector switch for maiutaining said switches in an operated position, and, in addition, maintains the trunk line leading to the connector busy to all other selectors having access thereto. Fur thermore, relay 5, at armature 35 and its working contact prepares the circuit for the vertical magnet 15 and at its resting contact opens a point in the release circuit; and at armature 36 and its working contact earths the holding conductor 51.

The calling subscriber may now manipulate his calling device in accordance with the remaining digits in the number of the private branch exchange, which in this case are assumed to be 1 and 1. In response to the operation of the calling device by the calling subscriber, the circuit of the line relay 4 is interrupted in known manner and the relay therefore deenergizes for a short interval. A circuit may now be traced for the vertical magnet 15 as follows: from earth by way of armature 33 and its resting contact, armature 35 and its working contact, normally closed off normal springs 60 and 61, slow series relay 6, and vertical magnet 15 to battery. The vertical magnet 15 and relay 6 energize in series, and by the operation of the vertical magnet. 15, the shaft and wipers are raised until the Wipers to 73, inclusive, are opposite to the first level. Relay 6 maintains its own circuit and that of the vertical magnet intact after the shifting of the ofi normal springs which takes place on the first vertical step.

After the first impulse, since there is only one in this case, the line relay 4 energizes again and opens the circuit for relay 6 and vertical magnet 15 at armature 33. Relay 6, upon deenergizing after a short interval, transfers the lmpulsing circuit from the vertical magnet to the rotary magnet at armature 40. Upon the dialling of the final digit of the called subscribers number, in this case the digit 1, the circuit of relay 4 is again interrupted. The line relay 4, upon deenergizing, completes parallel circuits for the rotary magnet 16 and relay 11 as follows: from earth, armature 33 and its resting contact, armature 35 and its working Contact, oif normal springs 60 and 62, armature 40 and its resting Contact, armature 41 and its resting contact, armature 42 and its resting contact, and the resting contact and armature 43 to rotary magnet 16 and the upper winding of relay 11 in parallel. The rotary magnet 16 and relay ljfenergize in parallel. The rotary magnet-16 steps the wipers 70 to 73, inclusive, into engagement With the bank contacts of the first trunk in the first level. Relay 11, upon energizing, at armature 54 and its working contact shunts armatures 42 and 43 so that the impulsing circuit will not be opened at armature 42 if the wiper '71 passes over busy trunks; at armature 56 disconneet-s the busy machine; and at armature 5;) completes a temporary holding circuit 'for its lowcr'winding including the resistance 53 and the earthed holding conductor 51. This holding circuit takes the place of the usual copper collar for preventing the relay 11 from deenergizing during impulses. The resistance 53 and the lower winding of relay 11 are so chosen that the relay will de- `energize shortly after the impulses stop. In

practiceit has been found that this tempo- 'rary holding circuit 'enables a greater number of contact springs to be provided than can be when the usual copper collar is used to render the relay slow to release. Relay 11, at armature 55 and its resting contact opens the circuit of the switching relay 9, and at the working contact of the same armature iprepares the testing circuit for relay 10. ssumn that the first set of bank contacts in the rst level are those of the first line of a group, in which case the bank contacts 74, 75, 76, and 77 will be connected tov terminals 7 0?, 71, 72", and 7 3",.respectively, of the terminal block TB, Fig. 2. Furtherlnore, let it be assumed that theV first line of the {i1-st level is busy, that is the bank contact 75 is earthed by the test wiper of another connector. The earth on bank contacts 75 energizcs test relay 10 by way of wiper 71, arma-ture 55 and its working contact, armature 64 and its restingRcont-act, winding of relay 10 to battery. clay 10, upon energizing, at armature 42 opens a point in the rotary impulsing circuit, at armature 18 prepares a locking circuit for itself, and at armatures 46 and 47 prepares a circuit for relay 8. A short interval after the rotary impulse is terminated, the slow relay 11 deenergizes, as its temporary locking circuit will not maintain lthe relay permanently energized, and at armatures 55 and 57 completes the following circuit for relay 85 battery, resistance 50, terminal 79, connecting link 58,'terminal 72a, bank contact 76, wiper 72, armature 57 and its resting contact, working contact and armature 46, lower winding of relay v8, working contact and armature 47, resting contact and armature 5,5, iwiper 71 to the earthed test contact 75. Relay 8, upon en irgizing, completes at armature 44 a locking circuit for its upper winding as follows: battery, upper winding of relay 8, working contact and armature l4.4, resting contact and armature 52 to the earthed holding conductor 51.

Stepping, relay 12 energizes in multiple with the upper windlng of relay 8 and in series with contacts 45. Stepping relay 12, upon energizing completes at armature 49 the :tollowing holding circuit for relay 8: battery, upper winding of relay 8, armature 49 and its working contact to the earthed holding conductor 51; at armature 32, completes parallel energizing circuits for relay 11 and rotary magnet 16. 'Rotary magnet 16. upon energizing advances the wipers to 73, inclusive, into engagement with the next set of bank contacts which, as will be seen from Figure 2, have their contacts corresponding to contacts and 76 connected together by the link 59. Rotary magnet 16 at its interrupter contacts 45, opens the circuit ot stepping relay 12 and the latter opens the circuit of the rot-ary magnet at armature 32. Relay l2 also opens the locking circuit for the upper winding of relay 8, which,

however, will not deenergize unless the test .contact of the next line is free. If it is bus its test contact will be earthed and the fo lowing circuit will be completed for relay 8: from the earthed test contact, link 59, contact in engagement with wiper 72, armature 57 and its working contact, armature 44 and its working contact, upper winding'of relay -8 to battery. Rotary magnet 16, upon deenergizing, closes its interrupter contacts 45, and stepping relay 12 ener 'zes again in multiple with the upper winding of relay 8, and again closes the rotary magnet circuit. The alternate operation of stepping relay 12 and rotary magnet 16 continues, if all the intermediate lines of the group arc busy, until the last line of the group is reached.

The last line of a group and also the individual lines do not have their test contacts connected by links such as 59 and consequently if the last line of a group is busy the contact engaged by wiper 72 will not be earthed. Relay 8 will now deenergize and open the circuit of rotary magnet 16 which will therefore leave the wipers 70-73, inclusive, in engagement with the last line of the group. The earth on the test contact engaged by test wiper 71,will maintain the busy relay 10 energlzed until its locking crcuit is completed by the make-before-break contacts controlled by armature 55 of relay 11. Relay 11, upon deenergizing connects at armature 56 and its resting contact the lead from the busy machine over armature 37 of 100 relay 10 to the lower speaking conductor 21. The calling party upon hearing the busy signal will replace his receiver upon the switch-hook whereupon line relay 4 will deenergize and open the circuit of slow relay 5 105 at armature 33. Slow relay 5 upon deenergizing disconnects earth from the release trunk conductor 22 at armature 34, whereupon the precedin switches are released in known manner. removes earth from the holding conductor 51 whereupon busy relay 10 deenergizes; at armature 35 completes the following circuit for release magnet 14; earth, armature 33 and its resting contact, armature 35 and its 115 resting contact, oil normal springs 13, release magnet 14 to battery. By the operation of the release magnet the switch shaft and wipers 70 to 73, inclusive, are restored to normal whereupon the off normal springs 12e 13 are shifted, opening the circuit of the release magnet 14 which thereupon deenergizes.

Returning now to the operation of the connector when it established connection 125 with the last line of a group', we will assume. that this line was idle and give a. detailed description of the operation of the connector under these circumstances. If the last line of the group is idle no earth poten- 130 elay 5 at armature 36 110 tial will be encountered by test wiper 71 and busy relay 10 will deenergize. Battery potential through thecut-off relay and rotary magnet of the wanted subscribers line switch (not shown) will now be encountered by test wiper 7l, and the following circuit will be completed for switching relay 9. Battery through the rotary magnet and cut ofi' relay of the line switch of the wanted line to test wiper 71, armature and its resting contact, armature 47 and its resting contact, lower Winding of switching relay 9, resting contact and armature 48 to the earthed holding conductor 51. Switching relay 9 and the line switch cut-off relay energize in series over the above traced circuit. The cut-off relayenergizes slightly before the switching relay 9 owing to the core of the latter relay being provided with a copper collar at its armature end. This is done to ensure that the cut-ofi' relay will have disconnected the normal battery and earth connections from the called line before the switching relay connects ringing current thereto. Switching relay 9, upon energizing, completes at armature 63 the following locking circuit for itself; battery, upper winding of relay 9, working contact and armature 63 to the earthed holding conductor 51; at armature 64 opens a point in the circuit of busy relay 10; at armature 65 earths the test wiper 71 thereby rendering the wanted line busy to -other connector switches; at armatures 66 and 67 connects interrupted ringing current from the ringing machine GEN. to the negative and positive line wipers 70 and 73 respectively; at armature 68 connects the small capacity con- `denser 80 across armature 38 and its working contact, whereby the calling subscriber is given the well known ring-back tone when ringing current is applied to the wanted line.

The wanted subscriber upon removing his receiver in response to the ringing of his bell, completes the following circuit for the ring-cut oif relay 7; earthed generator or booster battery at armature 69, lower winding of ring-cut off relay 7, resting contact and armature 38.l working contact and armature 66, wiper 70 over the wanted part-ys loop to wiper 73, armature 67 and its working Contact, armature 39 and its resting contact to battery. The ring-Cut ott relay 7 energizes over the above traced circuit and completes a locking circuit foritself at armature 78, and at armatures 38 and 39 disconnects ringing current from the called line and completes the talking circuit between the calling and called subscribers, and in addition, completes a circuit for the back bridge relay 3 as follows: From earth, lower winding of said relay by way of working contact and armature 39, working contact and armature 67, wiper 73 over the calling partys loop to wiper 70, armature 66 and its working contact, armature 38 and its working .contact to the upper winding of said relay and battery. The back bridge relay, upon energizing, reverses the flow of current to the calling subscriber at armatures 30 and 31. After the conversation has' been completed the release of the connection takes place in the hcreinbefore described manner upon the calling party replacing his receiver upon the switchhook.

Having described the operations which take place when the last line of a group is found idle it is not thought necessary to describe the operations which take place 'when an individual line is connected with as these are identical, the switch functioning in every respect as a non-rotary connector. A brief description will now be given of the operations which take place when a number corresponding to an intermediate line of a group is dialled. Referring now to the initial energizing -circuit for relay 8 it will be seen that this relay can only be energized through its lower winding being connected to battery and earth over wipers 72 and 71 respectivly. On referring to Fig.. 2 it will be seen that battery is only connected to the iirst line of a group, so that ifan intermediate line is dialled battery will not be encountered by wiper 72 and no circuit will be completed for relay 8 if the particular intermediate line should be busy. Since relay 8 controls the circuit for stepping relay 12 no hunting operation can take place when an intermediate line of a group is dialled. This feature is of great practical use as it enables any line of a group except the iirst to be listed in the directory for night service.

Referring now to the modification shown in Figures 3 and 4 we will assume that the calling subscriber has established his connection as far as the last selector, and that the selector has come to rest on bank contacts connected to conductors 120, 121 and 122 of the connector switch shown in Figure 3, this being the tirst idle connector accessible to the said selector. Vlien the selector switch comes to rest upon the contacts associated with conductors 120, 121 and 122, the switching relay of the selector completes an energizing circuit for the line relay 104 of the connector as follows: from earth by way of the lower winding of line relay 104, armature 112 and its resting contact, armature 113 and its resting contact, normally closed Contacts controlled by armature 131 of relay 103, conductor 121, over the intervening switches and the subscribers loop back to conductor 120, normally closed contacts controlled by armature 130 to the upper winding of line relay 104 and battery. Relay 104 at armature 133 and its working contact completes an energizing circuit for its slow to release relay 105. Relay 105 upon energizing earths to all other selectors'having access thereto.

Furthermore, relay 105 at armature 135 and its working cont-act prepares the circuit for the vertical magnet 115 and at its rest-ing contact opens a point in circuit for release magnet 114, and at armature 136 earths the holding conductor 151.

The calling subscriber may now manipulate his calling device in accordance with the remaining digits .in the number of the wanted party lin the private branch exchange, which in this case are assumed to be 1 and 1. In response to the operation of the calling device by the calling subscriber, the circuit of the line relay 104 is interrupted in known manner and the relay therefore deenergizes for a short interval. A circuit may now be traced for the vertical magnet 115was follows: from earth, by way of armature 133 and its resting contact, armature 135 and its working Contact, normally closed i" normal springs 160 and 161 to the vertical magnet 115 and battery. A circuit is also completed for relay 106 in parallel with the vertical magnet 115 as follows: oil' normal springs 161, resting contact and armature 116 to the lower winding of relay 106 and battery. The vertical magnet -115 and relay 106 energize in parallel, and by the operation of the vertical magnet 115, the shaft and wipers are raised one step. The wipers -7 3, inclusive, 'are now opposite the first level. )relay 106 maintains its own circuit and that of the vertical magnet intact at armature 117 after the shifting of the oil' normal springs which takes place on the first vertical step. Relay 106 also short circuits its upper winding at armature 118 thereby rendering the relay 106 slow to release during impulse transmission to the vertical magnet 115. Relay 106 is adapted to function as a slow to release change over relay from the directive vertical movement to the directive rotary movement and also is a quick acting stepping relay when the rotary magnet 116 is caused to operate automatically.

After the lirst impulse, since there is only one in this case the line relay 104 energizes again and opens the circuit for relay 106 and vertical magnet 115 at armature 133. Relay 106 deenergizes after a short interval, and transfers the impulsing circuit from the vertical magnet 115 to the rotary magnet 116 at armature 117. Upon the dialling of the final digit of therwanted number, in this case the digit 1, the circuit of line relay 104 is again interrupted Relay 104 upon deenergizing completes parallel circuits for the rotary magnet 116 and relay 111 as follows: from earth, armature-133 and its restmg contact, armature 135 and its working contact, oli'A normal springs 160 and 162,` armature 124 and its resting contact, armature 117 and its resting contact, resting'contact and armature 144, restingcontact and armature 153 to the rotary magnet 116 and the lower winding of relay 111 in parallel to battery. The rotary magnet 116 and relay 111 energize in parallel. The rotary magnet 116 steps the w1 ers 170-173 inclusive, into engagement wit the bank contacts 0f the first trunk in the first level. Relay 111 .upon energizing, shunts armature 153 and its resting contact at armature. 140, to prevent the impulsing circuit from being opened at armature 144 should the busy relay` 160 be energized by the test wiper 17 2 in passing over busy test contacts, at armai ture 141 short circuits its upper winding thereby rendering the relay 111 slow to de energize, at armature 142 opens the circuit of the switching relay 109 and connects test wiper 172 to the busy relay. 110; at arman ture 143 disconnects test wiper 171 from the upper winding of relay 108; and at armature 112 opens the normal short circuit about resistance 137 which includes its back contact and completes another over itsfront contact. y

Assuming that the first set of bankv contacts in the first level are those of the first line of a group in which case the bank contacts 174-177 inclusive will be connected to terminals 170-173 inclusive, respectively, of the terminalblock TB, Figure 4. Furthermore let it be assumed that the rst line of the group in the first level is busy, that is the bank contact 176 is earthedv by the test wiper of another connector. The earth on bank contact 17 6 energizcs test relay 110 by way of Wiper 17 2, armaturel 142 and its working contact, resting contact and armature 155 and ,the Winding of relay 110 to battery. Relay 110, upon energizing, opens -at armature 144 a point in the rotary impulsing circuit; prepares a locking circuit for itselrl at armature 146; prepares a circuit for relay108 at armature 145; and at armature 113 prepares a circuit for connecting the combined busy tone and busy flash conductor BET. to the' calling partys line. A short interval after the rotary impulse termina-tes the slow relay 111 deenergizes and at armatures 142 and 143 completes the following circuit for relay 10S: battery, reel sistance 163, terminal 164, connecting link 165, terminal 171', bank Contact 175, wiper 171, armature 143 and its back contact, upper winding of relay 108, Working contact and `armature 145, resting contact and armature 142, test wiper 162, to the earthed b ank contact 175. Relay 108, upon energizmg completes at armature 125 the following locking circuit for its lower winding, battery, lower winding of relay 108, armature125 and its working contact, resting contact and armature 141, conductor 151, working contact and armature 136 to earth. Relay 108 also prepares at the same armature one point in the circuit of the lower winding of relay 106; and at armature 127 completes the following circuit for lthe lower winding of relay 106; battery, lower winding of relay 106, armas ture 127 and its working contact, rotary interrupter springs 132, armature 125 and its working contact, resting contact and armature 141, to the earthed holding conductor 151; at armature 128 opens a point in the circuit for short circuiting the upper winding of relay 106; at armature 124 opens a point in the impulsing circuit and at arnia-` ture 126 prepares a circuit for the rotary magnet 116. Relay 106, upon energrzing completes at armature 123 the following locking circuit for the lower winding of relay 108 independently of relay 111; battery, lower winding of relay 108, armature 123 and its working contact, armature 126 and its working contact to the earthed holding conductor 151. Relay 106 at armature 119 completes parallel energizing circuits for rotary magnet 116 and relay 111 Rotary magnet 116, upon energizing advances the wipers 170-173 inclusive, into engagement with the next set of bank contacts which, as will be seen from Fig. 4, have their contacts corresponding to contact 176 and 175 connected together by a link 166. Rotary magnet 116 at its interrupter contacts 132, opens the circuit of relay 106 and the latter opens the circuit of the rotary magnet at armature 119. Relay 106 also opens at armature 123 the locking circuit for the lower winding of relay 108, which, however, will not deenergize unless the test contact of the next line is idle. If it is busy its test contact will be earthed and the following circuit will be completed for relay 108: from the earthed test contact, link 166,

. contactin engagement with wiper 171, armature 143 and its working cont-act, working contact and armature 125, to the lower winding of relay 108 and battery. Rotary magnet 116, upon deenergizing, closes its interrupter contacts 132, and relay 106 will energize again through contacts 132 and the working contact and armature 127 in multiple with the lower winding of relay 108. This alternate operation of relay 106 Aand rotary magnet 116 will continue, if all the 'intermediate lines of the group are busy,

until the last line of the group is reached.

The last line of a group and also the individual lines do not have the test contacts connected by links such as 166 and consequently if the last line of a group is busy the contact engaged by wiper 171 flash and busy tone lead BF T to the lowerA conductor 121 over resist-ance 137 and the normally closed contacts controlled by armat-ure 131. If the calling party is connected to an automatic exchange he will receive the busy tone over conductor 121. The busy Hash which consists of battery and earth alternately connected to the lead BFT will have no effect in this connection other than to maintain relay 104 energized over its lower winding should the calling party hang up at the instant when battery is connected to the lead BFT. Relay"104 will of course deenergize when the calling party hangs up and earth is connected to the leadBFT.

If, however, the call originates from an operators position the alternate connection of battery and earth to condutcor 121 will flash a supervisory signal in her cord circuit. When the calling party hangs up or the operator takes down the connection line relay 104 will deenergize and open the circuit of slow relay 105 at armature 133. Slow relay 5, upon deenergizing, disconnects earth from the release trunk conductor 122 at armat-ure 134, whereupon the preceding switches are released in known manner. Relay 105 at armature 136 removes earth from the"holding conductor 151 whereupon busy relay 110 deenergizes; at armature 135 relay 105 completes the following circuit for release magnet- 115; earth, 133, 135, 129, 114, battery. By the operation of the release magnet 114 the switch shaft and wipers are restored to normal whereupon the off normal springs 129 are shifted opening the circuit of release magnet 115 which deenergizes.

Returning now to the operation of the connector switch when it established connection with the last line of a group, we will assume that this line was idle and give a detailed description of the operation of the connector switch under these conditions. If the last line of the group is idle no earth potential will be encountered by test wiper 17 2 and busy relay 110 will deenergize. Battery potential through the cut-off relay and rotary magnet of the wanted partys line switch (not shown) will now be encountered by test wiper 172 and the following circuit will be completed for switching relay 109. Battery, through the driving magnet and cut-off relay of the line switch of the wanted line to test wiper 172, armature 142 and its resting contact, armature 145 andits resting contact, upper winding of switching relay 109 to the earthed holding conductor 151. Switching relay 109, u on energizing completes a locking circuit or itself at armature 154; at armature 155 opens a point in the circuit of busy relay 110; at armature 156 earths the `test wiper 172, at armatures 158 and 152 connects interrupted ringing current from the generator lead GEN. to the line wipers 170 and 173 respectively; at armature 157 connects the small capacity'ringing tone condenser 150 across armature 149 and its working contact.

W'heu the Wanted party removes his receiver the ringing current cut-off relay 107 energizes over the wanted partys loop and completes a locking circuit for itself at armature 148. Relay 107 also disconnects the ringing currentand completes the talking circuit at armatures 149 and 147. Relay 107 moreover completes at the same armatures a circuit for the back-bridge reversing relay 103. The back bridge relay 103 energizes and reverses the current over conductors 120 and 121 at armatures 130 and 131 for metering or supervisory purposes. After the conversation has iinished the release of the connection will take place in the hereinbefore described manner when the calling party replaces his receiver upon the switch hook.

The operat-ions which take place when a connection is made to an individual line are be energized by battery and earth over wipers 171 and 172. Since battery is only connected to the first line of a group relay 108 will not be energized when an intermediate line is dialed.

From the foregoing description it will be appreciated that a new and useful connector or final selector switch has been devised which functions as a rotary connector only when the first line of a group is dialed and as a regular non-rotary connector when any other number is dialed.

What is claimed is:

l. In a telephone system, a switch, groups of lines terminating in said switch, each group including more than two lines, means for directively operating said switch to select any line in any group, means effective only in case the first line in a group is selected and is found busy for auto atically causing the switch to hunt for an idle line,

a set of test contacts for each line, and

-lect any line in any group, means effective only in case a particular line in a group is selected and is found busy for automatically causing the switch to hunt for an idle line,

a set of test contacts for each line, and suitable circuit 'connectlons to said test contacts, the Cont-acts of some of sald sets being conconnected to the battery, for controlling the hunt-ing operation of said switch.

3. In a telephone system, a-switch having primary and secondary directive movements and an automatic hunting movement, groups of lines accessible to said switch, each group including at least threelines, means for operating the switch in its two directive movements-to selectvany group of lines and any line in the selected group, means responsive only to the selection of the first line in a group and then only in case said first line is found busy for causing the switch to operate in its hunting movement toautomatically select an idle line, a set of test contacts for each line, and suitable circuit connections to said test contacts, the contacts of some of said sets being connected together and other contacts being connected to the battery, for controlling the hunting operation of said switch.

4. In a telephone system, a switch having two test wipers, groups of lines accessible to said switch, means for operating said switch in a directive primary movement to select a group, 'means for operating said switch in a directive secondary vmovement to select a line in the selected group, and means operated over both said wipers in series and only in case the first line in the selected group is selected for automatically continuing the secondary movement to find an idle line.

5. In a telephone system, a connector switch having two test wipers, groups of lines accessible to said switch, means for directively operating said switch to select any line in any group, and means operated over both said wipers for causing said 4switch to automatically hunt for an idle line only in case the first line in a group is selected and is found busy, whereas if an intermediate line or the last line of a group is selected the switch is stopped whether the selected line is busy or idle.

6. In a switch, three different classes of terminal sets, means for directively operatnected together and other contacts being loo Cil

ing the switch' to preliminarily select a terminal set of any class, means etl'ective only in case a terminal set of the first class is selected and is found busy for operating the switch automatically to hunt over terminals of the second class, and means for stopping the hunting movement when the switch finds a terminal of the third class.

7. In a telephone system, a switch having two test wipers, a relay, means for bridging said relay across said wipers, and means responsive to the energization of said relay over a circuit including both said wipers in series for operating said switch in an automatic hunting movement.

8. In a telephone system, a switch having a directive movement and an automatic hunting movement, two-test wipers in said switch and contacts engaged thereby responsive to the directive movement of said switch, and a relay in said switch energized over a circuit including both wipers in series to start the hunting movement.

9. In a telephone system, a switch, groups of lines accessible to said switch. a set of terminals in the bank of said switch for each linc, each set of terminals including a regular test contact connected to the cut-off relay of the associated line and a special test contact, a conductor connecting the special test contact of the first terminal set of each group to the ungrounded pole of the battery, and conductors connecting the special test contacts of the intermediate terminal sets of cach group to their associated regular test contacts, respectively, the special test contact of the last terminal set of each group being left open.

10. In a connector switch having directive primary and secondary movements, a relay controlling the change over from the'first movement to the second, a local circuit for operating said switch in an automatic hunting movement. and contacts on said relay for sending impulses over said circuit.

11. In a connector switch having directive primary and secondary movements, a relay controlling the change over from the first movement to the second, a local circuit for operating said switch in an automatic hunting movement, contacts on said relay for controlling said circuit, and means for rendering the said relay slow acting while it controls the change over and quick acting while it controls said circuit.

12. In a telephone system, a switch, groups of lines terminating in said switch, each group including more than two lines, means for directively operating said switch to select any line in any group, and means efiective only in case the first line in a group is selected and is found busy for causing the switch to hunt for an idle line, said last means comprising test contacts for said lines and a distributing frame at which con- 1,ee4,623 l nections are made to certain of said .test contacts.

13. In a telephone system, a switch, groups of lines terminating in said switch, each group including more than two lines, means for directively operating said switch to select any line in any group, and means effective only in case a particular line in a group is selected and is found busy for causing the switch to hunt for an idle line, said last means comprising test contacts for said i lines and a distributing frame at which con-v nections are made to certain of said test contacts.

14. In a telephone system, a switch, groups of lines terminating in said switch, each group including more than two lines, means for directively operating said switch to select any line in any group, means including two test wipers for causing said switch to hunt for an idle line, and means controlled over .the said two test wipers for insuring that the hunting movement will take place only in case the first line in a group is selected.

15. In a telephone system, a switch,

groups of lines terminating in said switch, each group including more than two lines, means for directively operating said switch to select any line in any group, means including two test wipers for causing said switch to hunt for an idle line, and means controlled over the said two test wipers for insuring that the hunting movement will take place only in case a particular line in a group is selected. 16. In a telephone system, a switch havmg primary and secondary directive movements and an automatic hunting movement, groups of lines accessible to said switch, each group including at least three lines, means for operating the switch in its two directive movements to select any group of lines and any line in the selected group, and means responsive only to the selection of the first line in a group in case said first line is found busy for causing the switch to operate in its hunting movement to automatically select an idle line, said last means comprising test contacts for said lines and a distributing frame at which connections are made to certain of said test contacts.

17. In a telephone system, a Switch, groups of lines terminating in said switch, aypair of test terminals for each line accessible to said switch, means for directively operating said switch to select any line in any group, means effective only 1'n case the first line in a group is selected for starting the switch to hunt for an idle line, and means controlled over conductors connecting certain pairs of test terminals for continuing the hunting movement.

18. In a connector switch having directive primary and secondary movements, a

' from the first movement to the second, and

means for again operating said relay only in case the first line in a group of lines is selected for causing said switch to hunt for an idle line in said group.

19. In a rotary connector switch having,

directive primary and secondary movements to select a group of lines, a relay for controlling the change-over from the first to the second movement, and means for intermittently operating said relay to cause said switch to automatically hunt for an idle line in the group.

20. In an automatic switch having pri mary and secondary movements, a relay for controlling the change-over from the first to the second movement, and means for automatically operating said change-over control relay as a stepping relay during the secondary movement.

21. In a rotary connector having directive primary and secondary movements to select a group of lines, a primary magnet for the primary movement land a secondary magnet for the secondary movement, a relay for transferring the directive operating circuit `from the primary magnet to the secondary magnet, and means for automatically operating said relay as a stepping relay lfor controlling the operation of the secondary ma net to cause said switch to automat-icalIy hunt for an idle line in the group.

22. In a rotary connector Switch having directive primary and secondary movements, test terminals in the bank of said switch, a test wiper having access to said terminals, a relay for starting the operation of said switch in an automatic hunting movement, a circuit for said relay including said wiper and one of said test terminals having ungrounded pole of battery connected thereto, another wiper included in said circuit, and contacts engaged by said second wiper for continuing the hunting movement.

23. In a telephone system, a. switch, a group of lines accessible to said switch consisting of a rst line, intermediate lines, and a last line, a set of test contacts in the bank of said switch for each line, a set of auxiliary contacts for each line, a connection from each test contact in said switch bank to a corresponding one of said auxiliary contacts, a connection from one auxiliary vcontact of said first line to the un rounded pole of battery, and a connection tween the auxiliary cont-acts of each intermediate line, the auxiliary contacts of said last line being left unconnected.

24. In a telephone system, a calling subscribers line, a connector switch having two test wipers, groups of lines accessible to said switch, means controlled by the calling subscriber for directively operating said switch to select any line in any group, means operated in case said switch is directively operated to a first line in a group and said first line is idle for completing the desired connection from the calling line to said first line, and means operated over both said wipers for causing said switch to automatically hunt for an idle line in the selected group in case said first line is busy, said last means rendered inoperative in case a line of a group other than the first line of such group is d1- rectively selected whereby said switch is prevented from hunting regardless of the busy or idle condition of the selected line.

25. In a telephone system wherein a rotary connector switch having two test wipers is directively operated by a calling subscriber to connect with a first line, an intermediate line, or a last line in a group of lines depending upon the number of impulses transmitted by the calling subscriber and in case the line connected with is idle to seize the same for completing a connection, means operated over both said wipers for Causing said switch to automatically hunt for an idle line in said lgroup of lines in case the said first line is connected with and is found busy, whereas if an intermediate line or said last line in said lgroup is directively connected with by said switch the switch is stopped vhether the line connected with is idle or usy.

In testimony whereof, I hereunto subscribe my name, this 2nd day of December, 1924.

JOHN E. OSTLINE.

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