US1374184A - Telephone system - Google Patents

Description

E. C. BRITTON.

TELEPHONE SYSTEM.

APPLICATION FILED JULY 9.1917.

Patented Apr. 12, 1921.

2 SHEETSSHEET I.

Alfy.

E. C. BRITTON.

TELEPHONE SYS TEM.

APPLICATION FILED JULY 9,1917- 1,374, 184. Patented Apr. 12, 1921 2 SHEETS-SHEET 2.

Fig. 2.

v UNITED s'rA'r Es PATENT OFFICE.

ERNEST C. BRI'I'TON, OF NEW YORK, N. Y;, ASSIG'NOR TO -WESTERN ELECTRIC COM- PANY, INGOBPORATED, OF NEW YORK, N. Y.,'A. CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Apr. 12, 1921.

Application filed July 9, 1917. Srial'No. 179,412.

new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems and more particularly to telephone systems employing machine switching.

The object of this invention is the provision of means whereby switches employed in such systems may be operated to per? form either one of two selective functions each of which is usually performed in such systems by se arate SWItChGS.

More speci cally the object of this invention is the provision of means whereby a switch (which hereafter in the specification will be called a. combination switch) may be operated either as a selector'switch or as aconnector switch.

In accordance with this object the manner in which the combination switch op"- erates is determined by the path over which connection is made to theswitch. The trunk leading to each combination switch is multipled to contacts in line switches and to contacts in second selector banks.

When an idle one of the trunks is seized by a line switch, the combination switch connected thereto will be operated as a selector switch to extend the connection to a second selector switch. If the same idle tr is seized by'a second selector switch,

the combination switch will be operated as a connector switch to establish connection to a desired subscribers line. Each combination switchhas two sets of brushes and two terminal banks. arranged to move over contacts in a terminal bank in which trunks leading to second selector switches terminate. The other set of brushes is arranged to move over the contacts of the other terminal bank in which subscribers .lines terminate. The

One set of brushes is binationswitch. In response to the thousands series of impulses this combination switch is operated as an ordinary first selector switch to extend the calling line to an 1dle second selector. In response to the hundreds series of impulses this selected second selector switch is operated to extend the calling line to an idle combination switch in which multiple contacts of the desired subscribers line terminate. Since connectlon is made to this last combination switch from a second selector switch, this combination switch will be operated by the next two series of impulses, namely, the tens and units series of impulses, as an ordinary connector switch and the proper set of brushes will be selected to establish connection with the desired subscribers line.

In most of the full automatic systems now 1n use, the switches are provided on a ten per cent. basis, so that in a 10,000 line exchange there are 1,000 line switches or other equivalent non-numerical trunkhunting switches, 1,000 first selector switches, 1,000 second selector switches and 1,000 connector switches,. or a total of 1,000 switches. Theoretically 1,000 combination switches, or ten foreach group of 100 sub scribers lines, would be capable of performing the functions performed by the 1,000 first selector switches and the 1,000 connector switches. But since two combination switches are required for each connection, the maximum load on the system could be only one-half the maximum load on the system laid out on the ten per cent. basis. Therefore in each group of a hundred lines where 1,000 combination switches are used in a 10,000 line exchange, only ten subscribers could be using their telephones at the same time, whereas twent subscribers, ten calling and ten called, can e using their telephones in the system laid out on the ten per cent. basis.

In practice it has been found that twenty subscribers in a group of 100, do not as a rule use these telephones at the same time and that sixteen is much nearer the largest number. Therefore adopting sixteen combination switches for each group of 100 lines, we have 1,600 combination switches oria saving of 4,00 switches in an exchange of 10,000 lines. The use of this arrangement of combination switches also allows a wider flexibility of operation, for example,

there may be from O to 16 calling lines or 0 to 16 called lines at any instant in each group of 100 lines, if eight ordinary first selectors and eight ordinary connectors are used instead, the largest number of callin lines in a group of 100 lines is eight, an the largest number of called lines in a group of 100 lines is eight, although the maximum total number of calls at any one instant is the same, namely sixteen.

It is believed that the invention will be more clearly understood from the follow ing description of the accompanying. drawings, in which Figure 1 and Fig. 2 taken together diagrammatically show a circuit arrangement whereby a connection may be established between a calling substation 1,000 and a called substation 2,222, In Fig. 1 the circuits of a combination switch are diagrammatically shown whereby the calling line is extended to a second selector switch. At the left of Fig. 2 the circuits of a second selector switch are diagrammatically shown whereby thecalling line is extended to a combination switch, thecircuits of which are diagrammatically shown at the right of Fig.2. This combination switch extends the calling line to the called line.

In the present disclosure theinvention' is applied to a full automatic 10,000 line telephone exchange system, but it will be observed that the invention can be readily applied to larger or to smaller exchange systems or to semi-automatic telephone systems without departing from the. spirit of the invention.

The resent invention is specially designed or use with a switch of the general construction shown in patent to Keith et al, No. 815,176, March 13, 1906, but it will be necessary to modify this switch by providing it with an additional setof brushes and an additional contact bank to be traversed thereby. This would mean that the switch shaft would be extended upwardly, and a second set of brushes willbe secured to the shaft in the same manner as in the switch shown in said patent. bank would be provided havin terminals to be engaged by the upper set 0 brushes. As the switch structure shown in the above mentioned patent to Keith et al, is well known, a detail descriptionthereof is believed to be unnecessary.

It should be noted that the second selector switch is also provided with two sets of brushes. The reason for this is to reduce the time re uired for trunk hunting after the hundred s series of impulses has been transmitted. In the present disclosure 1 am assuming that there are 16 combination switches allotted to each group of 100 lines. Therefore, if only one brush set 'was used in each second selector switch, it would have to take sixteen steps before all the trunks station 1,000, contacts 2 and 5, conductor 9 A second terminal aeraiea leading to the combination switches, containing the lines of a particular group have been tested. In order to reduce the number of steps required, two brush sets are provided and operated simultaneously, each brush set being arranged to traverse half of the contacts of each group of the selector bank. In this way only eight steps at the most are required to test all the trunks in a selected group.

The preferred ty e of line switch to be used in the system isclosed is shown in Reissue Patent No. 14,236, reissued December 26, 1916, to J. N. Reynolds.

It is believed the invention will now be better understood by tracing a call from a calling subscriber at substation 1,000 to a called subscriber at substation'2,222.

en a subscriber at substation 1,000 removes his receiver from the hook, a circuit is completed for the line switch A for causing the contacts 1, 2 and 3 thereof, to move into engagement with the contacts 4, 5 and 6 of a trunk leading to an idle combination swltch. As soon asthe contacts 1 and 2 engagecontacts 4 and 5, a circuit is completed from grounded battery, right-hand winding of relay 7,,conductor 8, contacts 1 and 1 at line switch A, sender S, apparatus at subleft-hand winding of relay 7 to ground.

The energization of relay 7 completes a circuit from roundedbattery, winding of relay 10, con uctors 11 and 12, front contact and armature of relay 7 to ground. Relay 10 by attracting its left-hand armature connects ground through resistance 2( to contacts 6 and the multiples thereof, to cause these contacts to test busy. This ground is also connected to contact 13 and multiples thereof at the contact banks of second selector switches to cause these contacts to test busy. The attraction of this armature also completes a circuit from grounded battery, winding of relay 14, conductor 15, resistance 20, front contact and left-hand armature of relay 10 to ground. The energization of relay 14:. opens the circuit of release magnet 100 and thereby prevents the energization thereof when the secondary off-normal contact 138 is closed. The attraction of the right-hand armature of relay 10 prepares a circuit for the primary magnet 16 and the escape magnet 17. In response to the first series of impulses transmitted, the line relay 7 will be deenergized twice in the case I have assumed. Upon the first denergization thereof, a circult is completed from grounded battery, winding of primary magnet 16, side-switch arm 18, conductor 19, side-switch arm 21, ri ht-hand armature and front contact of re ay 10, outer left-hand armature and back contact of relay 22, back contact and armature of relay 7 to ground. A cirthe two sets of brushes carried thereon are placed in operative relation with the first level of contacts in their respective banks. In res onse' to the second denergization of relay the primary magnet 16 is again energized and moves the brush sets into op erative relation with the second level of contactsv 'in their respective banks. The relay 10 and the side-switch magnet 23. are

.so constructed that they remain energized during the short interruptions their circuits during the transmission of the roduced in impulses. After the second im ulse has been transmitted, the line relay remains energized, causing the esca e'relay 17 to remain deenergized for a su cient length of time to cause the denergization of the escape magnet 23 and thereby move the sideswitch arms to their .second position. In position 2 a circuit is completed from grounded battery, winding of secondary magnet 24, conductor 25, side-switch arm 18, conductor 19, side-switch arm 21, righthand armature and front contact of relay 10, inner right-handarmature and back contact of relay 22, side-switch arm 26, secondary off-normal contact 27 to ground. A circuit is also completed in parallel with the secondar magnet 24; from grounded battery, win ing of escape relay 17, con- -ductor 19 to ground at the secondary offnormal contact 27 over the circuit previously described for secondary magnet 24:. The energization of escape relay 17, completes an energizing circuit for the escape magnet 23 from grounded battery, winding of escape magnet 23, front contact and lefthand armature of escape relay 17 to ground. The energization of secondary magnet 24 moves the two sets of brushes on the brush shaft into engagement with the first set of contacts in the second level of their respective banks. It will be seen that since the relay 33 is denergized at this time, the brushes45','46 and 35 are connected through the back armatures and contacts of this re lay to the side-switch arms 43, 4:4: and 32 respectively, and that the circuits leading to the brushes 101, 102 and 103 are opened at the front contacts and armatures of this relay 33. Therefore, at this time, the movement of brushes 101, 102 and 103 over the terminals of the bank associated therewith does not aifect the operation of the combination switch. If the first set of terminals "engaged by brushes 45, d6 and '35, is busy,

ground will be found upon the test terminal thereof and a circuit will be completed from grounded battery, winding of test relay 29, conductor 31, side-switch arm 32, lower armature and backcontact ofrelay 33, conductor 34:,brush 35, terminal 36 to ground at the combination switch in engagement withthis busy trunk. This ground may be traced at said combination switch from contact 36, brush 35, conductor 34, sideswitch arm 32 in its third or fourth,

position to ground. The energization of 'test relay 29 completes at its inner armature and front contact a holding circuit for the escape magnet 23 from grounded battery, winding of escape magnet 23,

side-switch arm 37, conductor 38, front contact and armature of testrelay 29 to ground. Test relay 29 completes at its outer armature and front contact a stepping circuit for the secondary magnet 24 from grounded battery, winding of secondary magnet 24, conductor'25, side-switch arm 18, conductor 19, side-switch arm 21, right-hand armature and front contact of relay l0, inner right-hand armature and back contact of relay '22, side-switch arm 26, secondary off-normal contact 27 and its upper contact, which is closed by the first secondary movement of the switchv contact 28,

outer armature and front contact of test relay 29, interrupter 30 to ground. The secondary ma et 24 will be intermittently energized an deenergized vby the current flowing through thiscircuit. his operation of the magnet will cause the brushes 45, 46 and 35 and the brushes 101, 102 and 103 to move 'from one set of terminals to the next in the selected level of their respective banks until the brushes 45, 4:6 and 35 engcge a set of terminals of an idle trunk.

hen brush 35 engages the contact 36 of an idle trunk, no ground will be found thereon. and the test relay 29 willdeenergize and open the stepping circuit of the secondary magnet 24. The escape magnet 23 will also be deenergized by the relay 29 retracting its armature and it will move the side switch arms into their third position. In position 3, a circuit is completed from grounded battery, winding of escape relay 17, conductor 19, side-switch arm 18, back contact and armature. of marginal ringing relay 39 to ground. The energization of relay 17 completes a circuit for the escape magnet 23 from grounded battery, Winding of escape magnet 23, front contact and left hand armature of escape relay 17 to ground. The energization of escape magnet 23 completes a circuit from ground, ringing generator 10, marginal ringing relay 39, outer right-hand armature and back contact of relay 22, conductor 41, secondary ofl -normal contact 42, front contact and armature of escape magnet 23 to ground. The current flowing through this circuit is sufiicient to energize the marginal relay 39, which by 49 of the second selector switch, conductor 50, contact 36, brush 35, conductor 34, lower armature and back contact of relay 33, sideswitch arm 32 to ground. The release relay 49 by attracting its armature maintains the energizin circuit of release magnet 104 of the-secon selector switch open. As soon as side-switch arm 44 engages its third contact a circuit is completed for the line relay 51' r of the second selector switch from grounded battery, winding of line relay 51, sideswitch arm 52, line conductor 53, contact 48,

brush 46, conductor 54, middle armature and back contact of relay 33, side-switch arm 44, to ground. When the arm 44 moves into position 4 this circuit extends through conductors 11 and 12, front contact and armature of, relay 7 to ground. The arm 44 is so constructed that it engages its fourth con,- tact before it disengages its third contact. Therefore the circuit through line relay 51 is maintained closed duringthe movement of the arm 44 from its third to its fourth position. The energization of line relay 51 completes a circuit from grounded battery, winding of relay 55, front contact and armature of relay 51 to ground. The energization of relay 55 prepares a circuit for the side-switch magnet 56 and the primary magnet 57. The apparatus is now in condition for the second series ofimpulses which will again cause the line relay 7 to be deenergized twice in succession. Each'deenergization of line relay 7 opens the circuit for line relay 51 and causes the deenergization thereof. Relay 51 by retracting its armature completes a circuit from grounded battery, winding of primary magnet 57, side-switch arm 58, front contact and armature of relay '55, back contact and armature of relay 51 to ground. A circuit is also completed in parallel with the primary magnet 57 from grounded battery, winding of switch magnet 56, front contact and armatureof relay 55, back contact and armature of relay 51 to ground. The energization of primarymagnet 57 moves the brush shaft of the switch so that the two sets of brushes carried thereon are placed in. operative relation with the first level of contacts of their respective banks. In response to the second definergization of relay 5]., the primary magaraaea net is again energized to move the sets of brushes into operative relation with the second level of contacts in their respective banks. The .escape magnet 56 is so constructed that it remains energized during the transmission of the impulses; After the second impulse has been transmitted, the circuit of line relay 51 is again closed for a relativel long length of time, thereby causing the energizatlon of the escape magnet 56 to move the side-switch arms into their second position. The side-switch arm 52 in moving into its second position, opens the circuit of the-line rela 51, causing the deenergization thereof. ince relay 55 is made slow to release its armature, a circuit will be completed foruthe secondary magnet 59 at this time-from grounded battery, winding of secondary magnet 59 and its'armature and back contact, conductor 60, side-switch arm 58, front contact and armature of relay 55, armature and back contact of relay 51 to ground. A circuit is also completed in parallel with the secondary magnet 59 from grounded battery, winding of escape magnet 56, front contact and armature of relay 55, back contact and armature of relay 51 to ground. The f energization of secondary magnet 59 moves the two sets of brushes carried by the brush shaft into engagement with the first set of terminals in their respective banks. The movement of the brush shaft also closes the secondary off-normal contact 61.

We will assume that the first set of terminals engaged by each set of brushes is busy. This set of terminals will have ground connected to its test terminals. Therefore assoon as brushes 69, 68 and 67 engage ter minals 72, 71 and 70, a circuit will be completed from grounded battery, winding of relay 64, side-switch arm 66, test brush 67,

contact 70 to ground. A similar circuit will 1 be completed from grounded battery, winding of relay 65, side-switch arm 79, brush 73, contact 76 to ground. The energization of both of relays 64 and 65 completes a circuit from grounded battery, winding of test relay 62, side-switch arm 63, lower armature and front contact of relay 64, armature and front contact of relay 65 to ground. Test relay 62 becomes energized and completes a circuit for the secondary magnet 59 to move the brushes into engagement with thesecond set of terminals in their respective banks. This circuit may be traced fromgrounded battery, winding of secondary magnet 59 and its armature and back contact, conductor of the secondary magnet closed, but if either of these test brushes engages a test terminal of an idle trunk, the circuit of the test relay 62 will not be closed and the circuit for the sectndary magnet 59 will be maintained opened at the front contact of the test relay 62. v

We will assume that the second set of terminals-engaged by the two sets of brushes are both idle, therefore neither of the relays 64 and 65 will become energized and the test relay 62 will remain deenergized, The two sets of brushes will be left in engagement with the selected terminals of the respective banks. Since test relay 62 remains deenergized the circuit of the escape magnet 56, which is maintained closed through the front contact of this relay, is opened and moves the side-switch arms into position 3.

It will be noticed that since the relay 64 is deenergized at this time, the brushes 69, 68 are connected to the side-switch arms 81 and 80 at the back contact and armatures of the relay 64. Therefore, the trunk, which the brushes 69 and 68 have seized, will be used to establish the connection to the called line. The side-switch arm 66 in moving into position 3, completes a circuit from grounded battery, winding of release relay 82 of the Selected combination switch, conductor 130, test terminal 70, brush 67, side-switch arm 66, armature and back contact of relay 64 to ground. It will be observed that when side-switch arm 79 moves into position 3 ground will not be connected to the test terminal 76 because relay 64 is not energized. Therefore the idle trunk which the brushes 73, 74 and 7 5 have seized but which is not being used, may be seized and used by some other switch.

The energization of relay 82 opens the energizing circuit of release magnet 108 of the selected combination switch. The round which is connected to the .test terminal is also connected to the other multiple test terminals 70 and causes this trunk to test busy and it is also connected to the multipled terminals 131, at the line switches for the same reason.

As soon as the side-switch arm 80' moves into its third position, a circuit is completed from grounded battery, winding of relay 83,

conductor 132, contact 71, brush 68, armature and back contact of relay 64, side-switch arm 80, conductor 53, contact 48, brush 46-, conductor 54, middle armature and back contact of relay 33, side-switch arm 44, conductors 11 and 12, front contact and armature of relay 7 to ground. Relay 835by attracting its left-hand armature completes a circuit from grounded battery, winding of relay 107, conductor 110, front'contact and left-hand armature of relay 83 to ground.

Relay 107 by attracting its right-hand armature prepares a circuit for the primary magright-hand armature of relay 83 completes a circuit from grounded battery, winding of relay 84, front contact and armature of relay 83 to ground. Relay 84 by attracting its armatures removes this combination switch from under .the control of line relay 109 and places it under the control of relay 83. This relay alsocompletes a circuit from rounded battery, winding of relay 86, con uctor 85, inner left-hand armature and front contact of relay 84 to ground. Relay 86 by attracting its armatures disconnects the brushes 87, 88 and 89 from engagement with the side- switch arms 123, 124 and 125 and connects the side-switch arms to the brushes 90, 91 and 92,.which traverse the terminalsof the subscribers lines. The apparatus is now,

in condition for the last two series of impulses.

Tn response to the third series of impulses, line relay 7 will again be deenergized twice in succession. Each denergization of this relay opens a circuit of the relay 83, which causes the deenergization thereof. Relay 83 by retracting its armature completes a circuit from grounded battery, winding of primary magnet 111, side-switch arm 112, conductor 113, side-switch arm 114, righthand armature and front contact of relay 107, conductor 115, inner right-hand armature and front contactof relay 84, conductor 116, back contact and armature of relay 83 to ground. A circuit is also completed in parallel" with primary magnet 111 from grounded battery, winding of escape relay 117, conductor 113, to ground, at the armature and back contact of relay 83, over the circuit previously described for the primary magnet 111. Relay 117 by attracting its leftshand armature completes a circuit from grounded battery, winding of escape magnet 118, front contact and armature of relay 117 to ground. The energization of primary magnet-111 moves the brush shaft so as to place the two sets of brushes carried thereon into; operative relation with the first level of contacts of their respective banks.

In response to the second deenergization of relay 83, the primary magnet is again energized and moves the brushes into operative re ation with the second contacts of their respective banks. Relays 107 and 84 and escape magnet 118 are so constructed that they remain energized, during this operation deenergization of relay 83, however now described The first energization of the secondary magnet 126 moves the two sets of brushes into engagement with the first set of terminals in the selected levels. The second de'e'nergization moves the brushes into engagement with the second set of terminals. The brushes 90, 91 and 92 will thereby be in engagement with the terminals of the called line.

We will assume that this line is idle and therefore no ground will be found upon the test terminal thereof. As soon as relay 83 remains energized for a sufficient length of time to cause the dee'nergization of escape magnet 118, the side-switch arms move into the third position. A circuit is then completed from ground, generator 129, ringing relay 130, outer right-hand armature and front contact of relay 84, conductor 131, side-switch arm 125, upper armature and front contact of relay 86, brush 92, contact 133, sender S, apparatus at substation 2222, co'ntact'134, brush 91, middle armature and front contact of relay 86, side-switch arm.

124 to ground. A circuit at this time will also be completed from grounded battery, winding of relay 117, conductor 113, sideswitch arm 112, contact and armature of relay 130 to ground. Relay 117 by attracting its armature completes a circuit for rela 118 in a manner reviously described.

e circuit previously escribed through relay 130 is insuflicient to cause the energization of the rela due to the resistance of the rin r 136 atlt e substation 2222. As soon as t e called part removes his receiver, this relay receives su cient current to cause its energization, which 0 ens the circuit of the escape relay 117. he deenergization of relay 117 causes the deenergization of escape magnet 118 to move the side-switch arms into their fourth or talking position. As soon as the side-switch arm 123 moves into its third position, ground is connected through the -side-sw1tch arm .123, lower armature and front contact of relay 86, brush 90 to contact 135 and the multiples thereof, to prevent the called line from being selected by any other switch. The apparatusis now in condition for the subscribers to carry on conversation. The talking current is supplied to the calling side of the line from grounded battery, right-hand Winding of relay 7, conductor 8, contacts 4 and 1 through the apparatus at substation 1000,, sender S, contacts 2 and 5, conductor 9, left-hand winding of relay 7 to ground. The talking current is supplied to the called line from grounded battery, resistance 137, side-switch arm 125, upper armature and Lemma front contact of relay 86, brush 92, contact 133, sender S, apparatus at substation 2222, conductor 134, contact 91, middle armature and front contact of relay 86, side-switch arm 124, conductor 110, front contact and left-hand armature of relay 83 to ground.

When the subscribers are through talking and the calling subscriber at substation 1000 replaces his receiverupon its hook,'line relay 7 becomes decnergized, causin in turn the de'nergization of relaylO. lay 10 by retracting its left-hand armature removes ground from the test terminals 6 and 13 and also causes the denergization of release relay 14. A circuit is-then completed for the release magnet 100 to return the switch to its normal position. This circuit is traced from grounded battery, winding of release magnet 100, secondary off-normal contact 138, armature and back contact of relay 14 to ound. Relay 100 by attracting its rig t-hand armature completes a locking circuit for itself which remains closed until the switch reaches its normal position, at

which time the secondary off-normal contact 138 is opened. As soon as the side-switch arm 32 returns to its normal position, the circuit for release relay 49 is opened, causing the energization of release magnet 104 of the secondselector switch from grounded battery, winding of release relay 104, secondary off-normal contact 139, outer and back contact of release relay 49 to ground.

The energization of this magnet allows the switch to return to its normal position and also closes the locking circuit for itself from grounded battery, winding of release magnet 104, secondary off-normal contact 139, front contact and armature of release magnet 104 to ground. As soon as the switch reaches its normal osition, this locking circuit is opened at t e secondary off-normal contact 139. As soon as the side-switch arm 66 leaves its third position, the circuit of release relay 82 is opened and a circuit is completed for release magnet 108 from grounded battery, winding of release magnet 108, secondary off-normal contact 140, back contact and armature of. relay 82 to ground. The energization of release ma net 108. causes the release of the combination switch associated therewith and also completes a locking circuit for itself from grounded battery, winding of release magnet 108, secondary ofi-normal contact 140, front contact and armatureof release magnet 108 to ground. As soon as the combination switch reaches its normal position, this locking circuit of release magnet is opened at the secondary off-normal contact'140.

If the called line has been busy at the time the brushes 90, 91 and 92 engaged the terminals 135, 134 and 133, ground would have which of said functions said switch will' perform.

2. In a telephone exchange system, a

for relay 121 from grounded battery, winding of test rela 121, conductor 122, sideswitch arm 123 1n its second position, lower arnrature and front contact of relay 86, brush 90, contact 135 to ground through arm 123 and its third or fourth position of the switch connected to the called line. The energization of test relay 121' completes a holding circuit for theescape magnet 118 and prevents it from denergizing and moving the sideswitch arm into position 3. This holding circuit is traced from grounded battery, winding of escape magnet 118, side-switch arm 128, conductor 127, front contact and inner armature of relay 121 to ground. A circuit will also be completed at this time for connecting the busy tone to conductor 119 leading to the calling subscribers substation. The circuit is traced from ground, busy device 141, middle armature and front contact of test relay 121, middle armature and front contact of relay 84, back contact and armature of relay 117, which will be deenergized at this time, conductor 142 and conductor 14:3 to conductor 119. The calling subscriber hearing this busy tone will replace his receiver on its hook and cause the apparatus to release in the same manner as above described. 7

What is claimed is:

' 1. In a telephone exchange system, a switch arranged to perform the functions of either a selector switch or of a connector switch, said first mentioned switch being reached by a plurality of paths, and means controlled by the path over which connection is made to said switch for determining switch arranged to perform the functions of either a selector switch or of a connector switch, said first mentioned switch being reached by a plurality of paths, means comprising a relay for determining which of said-functions said switch will perform, and a circuit for said relay controlled by the path over which connection is made to said switch.

3. In a telephone exchange system, a

' tromagnetic switching device for determining which of said functions said switch will perform, and a circuit for said device controlled by the path over which connection is made to said switch.

5. In a telephone exchange system, a switch arranged to perform the functions of any one of a plurality of different kinds of automatic telephone switches, a connecting circuit extending to said switch, multiple terminal contacts for said circuit at which said circuit may be selected, and means dependent on at which of said multiple terminal contacts said circuit is selected for determining which of said functions said switch will perform.

6. In a telephone exchange system, a switch arranged to perform the functions of any one of a plurality of different kinds of automatic telephone switches, a connecting circuit extending to said switch, multiple terminal contacts for said circuit at which said circuit may be' selected, an electromagnetic switching device for determining which of said functions said switch will perform,

and a circuit for said device controlled by' the path over which connection is made to said connecting circuit.

7. In a telephone exchange system, subscribers lines, a switch having an automatic secondary movement and a secondary movement under the control of a calling subscriber, a connecting circuit extending to said switch, multiple terminal contacts for said switch at which said circuit may be selected, and means dependent upon at which of said multiple terminal contacts said circuit is selected for determining the secondary movement of said switch.

8. In a telephone exchange system, subscribers lines, a switch having an automatic secondary movement and a secondary movement under the control of a calling subscriber, a connecting circuit extending to said switch, multiple terminal contacts for said switch at which said circuit may be selected," an electromagnetic switching device for' determining the secondary movement of said switch, and a circuit for said device. completed when said-connecting circuitsis selected at certain of its multiple terminal contacts.

9. In a telephone exchange system, subscribers lines, a switch havingan automatic secondary movement and a secondary movement under the control of a calling sub-- sets of brushes for said switch, series of.

. contact sets, one for each set of brushes, means for moving said brushes to simultaneously traverse said contacts, a connecting" circuit extending to said switch, multiple terminal contacts for said switch at which said circuit may be selected, and means dependent upon at which of said multiple terminal contacts said circuit is selected for determining which of said brush setswill be rendered operative and which of said functions said switch will perform.

11. In a telephone exchan e s stem, a switch arranged to perform t e' unctions of any one of a plurality of different kinds of automatic telephone switches, a plurality of sets of brushes for said switch, series of contact sets, one fonieach set of brushes, means for moving said brushes to simultaneously traverse said contacts, a connect- .ing circuit extending to said'switch, multi le terminal contacts for said switch at WhlCh said circuit may be selected, an electromagnetic switching device for determining which of said brush sets will be rendered 0p erative and which of said functions said switch will perform, and a circuit for said device controlled by the path over which connection is made to said connecting cir cuit.

12. In a telephone exchange system, subscribers lines, trunk lines, a switch in which said lines terminate, said switch being arranged to perform the functions of a line connector or a trunk selector, a connecting circuit extending to' said switch, multiple terminal contacts for said connecting circuit at which said circuit may be selected, and means dependent upon at which of said multiple terminal contacts said circuit is selected for determining which of said flmc- I tions said switch will perform.

13. In a telephone exchange system, a switcharran ed to perform the functions of a selector switch or a. connector switch, subscribers lines,trunk lines,'a plurality of sets of brushes for said switch, groups of contacts in which said subscribers l1nes terminatearran ed for engagement by one of said sets 0 brushes, groups of contacts in which said trunk lines terminate arranged for engagement by another of said sets of brushes, a connecting circuit extending to said switch, multiple terminal contacts for said connecting circuit at which said circuit may be selected, and means operative when connection is made to said connecting circuit at certain multiple terminal contacts for selecting the set of brushes which traverse the contacts of subscribers lines and for causing said switch to perform the functions of a connector switch and when connection is made to said connecting circuit at certain other multiple terminal contacts for selecting the set of brushes which traverse the contacts of the trunk lines and for causing said switch to perform the functions of a selector switch.

14:. In a telephone exchange system, a switch arranged to perform the functions of. a selector swltch or a connector switch, subscribers" lines, trunk lines, a plurality of sets of brushes for said switch, groups of contacts-in which said subscribers lines termi'nate arranged for engagement by one of may be selected, an electromagnetic switching device arranged when energized to select the set of brushes which traverse the contacts of subscribers lines and to cause said switch to perform the functions of a connector switch and arranged when denergized to select the set of brushes which traverse the contacts of the trunk lines and to cause the switch to perform the functions of aiselector switch, and a circuit for said device controlled by the path over which connection is made to said connecting circuit. 1

V 15. In a telephone exchange system, a switch arranged to perform the functions of either a selector or a connector, a plurality of paths by which said switch may. be reached, a plurality of brush sets for said switch, contacts for said brush sets, means .for simultaneously moving said brush sets over said contacts and means controlled by the path over which connection is made to said switch for determining which of said brush sets will be rendered operative to ex tend said path.

16. In a telephone exchange system, a switch arranged to perform the functions of either a selector ona connector, a plurality

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