US1504293A

US1504293A - Telephone-exchange system

Info

Publication number: US1504293A
Application number: US332918A
Authority: US
Inventors: Jr Samuel B Williams
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1919-10-24
Filing date: 1919-10-24
Publication date: 1924-08-12
Anticipated expiration: 1941-08-12

Description

Aug? my mm 1,504,293

' 8. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM Filed Oct. 24. 1919 4 Sheets-Sheet l flung m 1924..

S. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM Filed Oct. 24 .1919

4 Sheets-Sheet 2 S. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM w km mm Patented Aug. 1%, i924,

SAMUEL B. WILLIAMS, 31%., OF BROOKLYN, NEW YORK, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INGQRE'ORI? YORK.

, G l? NEW YORK, N. Y., A GQBIPQRATION OE" NEW aiXCIi-LANGE SYETEH.

Application flied Gctober 24;, 1919. fierial No. 332,918.

To all whom it may concern:

Be it known that I, SAMUEL B. VVILLIAMS, Jr, a citizen of the United States, residing at Brooklyn, in the county of Kings and 5 State of New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

My invention relates to an improved telephone system, and more particularly to emergency apparatus for use in a telephone system of the call distributing type.

It is the particular object of my invention to provide a telephone organization of such a character that alternative or duplicate operating parts are available for use when the normal operating parts fail to function properly, and such that these alternative or duplicate parts are brought into service as the result of a test periodically and automatically made upon the parts normally in service, which test is responsive to the failure of the normally operating parts to function properly.

In a telephone call distributing system of the type in connection with which this invention is particularly designed and adapted to be used, the switches that act to extend the circuit of any calling line to the operators position are controlled through the medium of a distributor switch or test ing switclr that continuously operates to make consecutive tests upon all of the lines in the group with which the distributor switch is associated. When the terminals of a calling line are passed over by the distributor switch, certain. group apparatus is operated which identifies the particular group in which the calling line is located, and which also causes the operation of common starting apparatus to start one of the line finding switches and trip the set of brushes corresponding to the identified calling line group. As the distributor switch is the medium 4 through which the calling lines of the associated group control the line finding switches and through which therefore the lines of this group have access to the operator, any failure of the distributor switch to function properly may serve to shut out all of the lines served by this switch in order to minimize the possibility of such a shutting out of all of the lines of a group, the system herein disclosed is so organized that while each group normally has control over line finding switches through the medium of one distributor switch, there is an alternative path provided for each group of lines through another distributor switch; and in order to reduce the amount of apparatus and simplify its operation, each distributor switch is constructed and connected so as to have the ca pacity for serving two groups of lines, one of which groups is served normally and the other of which is served alternatively in case of the failure of the distributor switch normally serving that group of lines. The distributor switches are thus arranged in teams or pairs, and are connected with the group testing apparatus of their respective groups through the medium of switches which may be operated in case of emergency, or when desired, to throw all of the load onto one of the switches and leave the other switch idle for inspection and adjustment or repair.

Furthermore, the organization is such that each distributor switch at a certain point in its line testing operation, and preferably once in each complete group testing operation, establishes a testing circuit to which certain associated signal devices respond in case the distributor switch is not operating properly. Upon the operation of these sig nal devices, indicating trouble in the associated distributor switch, the attendant may throw a switch that disconnects the associated group circuit from the defective switch and connects it with the other distributor switch of the team or pair. The organization is such that, in order to economize apparatus and simplify the operation, the periodical test is made in part through the medium of certain of the apparatus which also acts as a part of the line testing apparatus in the line finder switch starting operation; and provision is also made to suppress the periodical test when the group apparatus associated with the distributor switch is engaged in responding to a calling line, and to prevent the periodical test from interfering with the normal operation of the line testing and switch starting apparatuses of the other associated line groups. The manner in which these and other ad vantageous results are accomplished will be fully explained in the detailed description of the system that follows.

' The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. 1 shows a side elevation, partly in section, of a form of distributing switch adapted for use in the system of the invention; Fig. 2 is an end elevation of the distributor switch with parts shown in section; and Figs. 8, a and 5 inclusive, taken together and placed side by side so as to join the lines extending to their margins, represent diagrammatically as much of a complete circuit organization as is necessary to an understanding of the invention.

Theportion of the entire circuit organ-.

ization thatis shown, comprises two groups of lines G and G, represented by two lines in each of these groups. One line in each group is represented as extending to a subscribers station, A A. respectively. The

t- M. 3 N -wo groups of -ines J and u are 1epre sented as being multipled to stationary terminals on the line finder switches LF and LF, these switches being two of a larger group of line finder switches serving the two groups G and G and other like groups of telephone lines. In the typ 2 oi call distributing system which is chosen for the purpose of illustrating a practical embodiment of the invention, there are customarily ten groups G, G, etc, of lines, with fifty lines in each group; and these ten groups of lines are served by some sixty line finder switches LF, LE, etc., each line finder switch having ten sets of brushes and ten groups of terminals, one for each of the groups of fifty lines served.

Associated with each two line groups G and G, are two distributor switches D and D. Each of these distributor switches is provided with one hundred sets of stationary line terminals, to fifty of which thelines of one group of fifty are connected, and to theother fifty of which the lines of the other group of fifty are connected, the lines of each group of fifty being multipled. to corresponding terminals on each of the two distributor switches. Each of the distributor switches also has certain additional terminals which cooperate in the periodical test which is made of the switches operativeness.

Each of the line groups has associated with it certain regular test relays 10 and 11, special or

periodical test relays

20, 21, 22 and 23, and

group relays

12 and 13. Starting apparatus including the relays 71, 72 and 73 is provided which is common to and under the control of all of the sets of

group relays

12 and 13 of the various line groups, the starting apparatus acting to control the starting oi one of the group of line finder switches LE, LF, when any telephone line of any of the groups calls. There is also an alarm relay 74:, a signal or hell 89 and a control key 7 5 common to the periodical testing relays of the various line groups. and an emergency lam) 20 for identifying the particular group in which trouble occurs. The above-mentioned responsive and controlling apparatus of each group has operative connection with the distributor switches of the correspondins group through the medium of a switch he 50. by means of which the group and testing apparatus may be brought into operative relation with the telephone lines of its group by way oi either one or the other of the pair out disi ributor switches D and D that serve this and the associated line group.

Each line finder switch LE, Li etc. serves as one of the terminals of one oi the finder circuits F, F, etc, respectively; the other end of each finder circuit terminating in a switch CS through the medium of which the circuit of a calling line that ha. been connected with by a line finder switch 1112i be further extended. These finder circuits F, F, etc., are so interrelated that only one of them at a time is in readiness to respond to the operation of the starting apparatus to cause the starting of the corresponding line finder switch to find a calling line. The wiring of finder circuits is illustrated only to such an extent as is necessary to show the manner in which the line finder switches are operated to connect with and disconnect from the calling lines, and the manner in which the finder circuits of a group oi such circuits are interrelated. Inasmuch as The invention has to do only with certain tom turcs of such call distributing telephone system as has been chosen to illustrate zuembodiment of the invention. such parts of the system as are unnecessary to a lull u de standing of the invzntion are omitted. A complete call distributing system oi the type to which the present invention pertains. and in connection with which the particular teatures herein disclosed may be used, is illustrated and described in Patent 1304.041. issued to S. B. ll illiams, J12. May 2?. MW).

The preferred form of distributing switch illustrated in Fig. 1 and Fig. 2 comprises a stationary drum on which the line terminals and test terminals are mounted, a rotating yoke or pair of arms carrying two sets of brushes for engaging the GXDOSG-il surfaces of the line and test terminals on the periphery of the stationary drum. a commutator with two sets of stationary brushes 111, 112. 113, 114i and 121. 122, 123, 124 through which the two sets of rotating brushes are connected with the external circuit, and driving mechanism comprising the

spur gear wheels

104 and 109 and the bevel gear wheels 119 and 129 with the clutch 136 for connecting the train of gears with the driving shaft 135. The above-mentioned parts are mounted upon the supporting frame 101. The stationary drum 100 is made ill) I Iii IIEU minals being located close together.

up of four divisions or

discs

130, 1 10, 150 and 160, each consisting of a series of alternate conducting and insulating segn'ients. The conducting segments of the disc 130 are used as test terminals, and the conducting segments of the discs 1 10, 150 and 160 serve as the line terminals of the switch; in addition to which each of the

discs

130, 1 10, and 150 is provided with supplementary test terminals 14.1, 151 and 161. The terminals of the four discs are arranged in two symmetrical semi-circular series. The test disc 130 has two sets of

test terminals

131, 132 and 133 placed at diametrically opposite points in the disc, there being a relatively long insulating space between the terminal 131 and the

terminals

132 and 133, the last two ter- The balance of the disc 130 is of insulating ma terial. Each of the discs 1 10, 150 and 160 has two series of fifty consecutive terminals,

the two series being separated by relatively long segments of insulating material. Upposite these relatively long segments of in sulating material in the

line terminal discs

140, 150 and 160 the

test terminals

131, 132 and 133 of test disc 130 are placed, and each of the line discs has a

supplementary test terminal

141, 151 and 161, respectively, placed opposite the insulating space between the

test terminals

131 and 132 of the test disc.

These stationary terminals of the drum 100 are engaged at diametrically opposite points by two sets of

brushes

115, 116, 117, 118, and 125, 1.26, 127, 128, carried on the yoke 110, and insulated from the yoke and from each other. These sets of brushes are electrically connected with two sets of corresponding semi-circular segments 1.05, 106, 107 and 108 on the commutator 120. The commutator 120 with its two sets of four semi-circular segments is mounted on the shaft 103 and rotates therewith. The seg ments of the rotating commutator 120 are engaged by two sets of

stationary brushes

111, 112, 113, 1141- and 121, 1.22, 123, 12 1. The relationship between the various parts is such that the

brushes

121, 122, 123 and 124 come into electrical connection through the segments of commutator 120 with the rotating

brushes

115, 116, 117 and 118 an instant before the rotating brushes commence to pass downward over the contact terminals in the lower semi-circular divisions of the

discs

130, 140, 150 and 160; and at the same time the

stationary brushes

111, 112, 113 and 114 come into electrical connection with the rotating

brushes

125, 126, 127 and 128 an instant before they start to move upward over the stationary terminals in the upper semicircular divisions of the

discs

130, 1410, 150 and 160. The fact that there are two sets of rotating brushes constantly engaging diametrically opposite portions of the contact drum 100 causes each of the stationary sets of brushes to be constantly in ire relation with its corresponding of the contact terminal drum one or the other of the two sets o if rotating brushes,

The rotation of the brush carrying yoke 110 and commutator 120 of the distributor a .Jitch is brought about through the agency of a train of gears COUpllDg the driven shaft 103 of the distributor switch with the driving shaft 135. The driven shaft 103 carries a gear 10 1 meshing with a pinion 109 journaled on the supporting frame 101; and at the other of the short shaft carrying the pinion 109 is one member 119 of a pair of bevelled gears, the other member 129 of which is idly mounted on the driving shaft 135, and is rotatably connected with or disconnected from the driving shaft by means of a jaw clutch 136 operated by means of a lever 137;

The line finder switches LF and LF may be substantially like the switch illustrated and described in Patent No. 1,177,041 to James L. McQuarrie, issued March 28th, 1916. The line tinder switch comprises a longitudinally movable shaft 1, carrying as many sets of brushes 2 as there are groups of stationary terminals to be engaged. To move the shaft up, an extension at the lower end of the shaft is brought into engagement with the constantly rotating power member 3 by means of an idler wheel operated by the up drive magnet 61; and to move the shaft down, the extension is brought into engagementwith the power member 41 by means of an idler wheel operated by the down-drive magnet 62. Normally the brushes of each of the sets 2 are held apart so as to clear the terminals of the associated groups by means of aseparating cam 5 located between the innermost brushes of the set. The earn 5 is rotatably mounted, and when swung in one direction releases the brushes and permits them to engage the associated terminals. The tripping or releasing of the brushes is controlled by a number of trip magnets, 16 and 17. Each of these when energized rotates an associated trip rod 6 that extends transversely of the switch shaft 1 and carries as many trip yokes 7 as there are finder switches in the group. The trip rod in rotating brings all of its trip yokes 7 into position to operate the brush controlling cams 5 of the corresponding sets of brushes onall of the switches, so that whichever of the finder switches is caused to more up, has that set of brushes tripped that corresponds with the

particular trip magnet

16, 17, that is at the time energized. When the finder switch that has been in use is returned to its normal position, any of the associated controlling cams 5 that has been tripped is engaged and rotated in a reverse direction to separate its switch springs again and thus render them inactive. Each of the line finder switches has associated with it a commutator 8, which comprises a number of stationary commutator segments and a set of movable brushes carried at the top of the switch shaft 1 and cooperating with the stationary segments. -This commutator serves to make and break certain of the controlling circuits in various stages of the movement of the associated switch shaft.

F or cooperating in the control of its conductors, each of the finder circuits F has as sociated with it a sequence switch that is generally indicated by the reference number 200. These sequence switches may be of the type disclosed in a Patent 1,127,808 issued February 9th, 1915, to Reynolds & Baldwin. Each consists of an electromagnetically controlled motor or driving mechanism and a number of associated switch cams. These cams are designated 201 to 217 inclusive. Each cam has one or more contact points associated Wlt-h'it to which are applied certain numerals; In the case of cam 201 of sequence switch 200, these niunerals indicate the only positions of the associated sequence switch in which this cam opens its contact. The numerals applied to the contacts of all the other sequence switch cams indicate the only positions of the sequence switch in which the contacts to which the numerals are applied are closed. As cam 201 acts directly to close the energizing circuit of the motor magnet of the sequence switch 200 in all positions of the sequence switchexcepting those that areindicated by the numerals applied to the contact of cam 201, the sequence switch 200 can come to rest only in

positions

1, 2, 3, 5, 6, 7, 8, 14, 15, 16 and 17.

In outline the operation of the system in so far as the features to which the invention particularly pertains, is as follows :Each two groups of telephone lines, as determined by the group arrangement of the line terminals on the finder switches LF, are provided with two distributor switches D and D. The lines of the two groups served by each pair of distributor switches are connected respectively with the two semi-circular divisions of line terminals on these switches, and the brushes of the two switches constantly move over and test these line terminals, the brushes of one distributor switch normally testing the line terminals of one group and the brushes of the other distributor switch normally testing the line terminals of the other group. When the brushes of either distributor switch pass over the terminals of a calling line in the group that this particular distributor switch is testing, the test relays 10 and 11 of the associated group of lines respond in such a way as to cause the energization of the associated group relay 12, and also the energization of the associated group relay 18, provided the relays 72 and 73 of the starting apparatus are not at the time operated in response to a calling line of some other group. The operation of the group relay 13 energizes the trip magnet, 1.6 or 1. of the corresponding group, and also operates the start relay 72 to cause the starting of the particular line finder switch LF which is in readiness to a call, this being determined by the fact that its sequence switch is standing in position lVhen the upward movement. oi the line finder switch starts, the set of brushes corresponding to the

particular trip magnet

16, 17, etc., that is operated is tripped, and the upward movement of the tripped set of brushes continues until the terminals of the calling line are encountered, when the movement of the switch is stopped and the brushes brought to rest in engagement with the terminals of this particular line. As the brushes are tripped at the outset of the upward movement of the switch, the starting relay '1' 2, the group relay 13, and the trip magnet 16 are released, and a moment later upon the release of relay T3 the circuits are made available for responding to a. call from another telephone line.

Immediately before the brushes of each distributor switch commence their testing movement over the line terminals of a group of lines, the switch brushes come into engagement with the special or periodical testing contacts. The result of this is that the relay 20 of the periodical or special testing group first operates to rearrange the circuits in readiness for the special test, so that the test will not cause the starting of a line finder and the tripping of its ln'ushes, or prevent a calling line in another group from having access to the starting circuit; then a special testingcircuit through an artificial line, consisting of resistance coils 21- and 25, is closed for relays 10 and 11 to bring about the response of the relay 12, in case the dis tributor switch is functioning properly; then the relay 22 is connected in circuit in such a way as to cause it to respond and operate the common alarm 89 and light the group emergency lamp 26 in case relay .12 has not responded to the closure of the special testing circuit; and finally the relay 23 is operated to release the special test relays 20 and 21 and the group relay 12 and restore the circuits to their normal condition in readiness to commence the normal testing operation of the lines of the associated group. In case the automatic periodical testat any time indicates by the sounding of the alarm 89 and the lighting of the group lamp 26 that a distributor switch is not functioning properly, the switch 50 is thrown to bring the distributor circuits of that group into operative relation with the telephone flu lines of the group .through the medium of the other distributor switch of the pair.

The operation of the system will be now described in detail upon the assumption that the subscriber at stationv A is calling. lVhen the subscriber takes his telephone receiver from its hook a connection is established between the two sides or limbs of the line by way of the switch hook contacts. The two distributor switches D and D that serve the group in which the calling line is located have their brushes constantly rotating; and in this rotation, first one and then the other set of the two sets of rotating brushes of each distributor switch is caused to pass over the terminals of the line group that includes the line extending to station A. As each set of brushes of each distributor switch comes into engagement with the terminals of this line group, these brushes are connected through the medium of the com mutator and the lower set of commutator brushes 121, 122, 123 and 12 i with the con tact points of the switch 50. The switch springs of the switch 50 may be thrown to engage either one or the other of its sets of contact points to extend the conductors leading from either one or the other of the distributor switches D and D to the relays and 11. In the present instance, as illustrated in Fig. 3 of the drawings, the switch is thrown toward the left so as to connect the relays 10 and 11 with the rotating brushes of the distributor switch D. Consequently when either set of rotating brushes of the distributor switch D passes over" the terminals of the line extending to the calling station A, a circuit is completed for the energization of the relay 11 by way of contacts of the relay 10. The circuit of the relay 10 is completed from battery through the winding of the relay, switch spring 52 and lett-hane corresponding contact of the switch 50, thence by way of commutator brush 122, rotating brush 126, sleeve contact 1412 of the calling line and sleeve resistance 27 oi that line to ground. Relay 10 operates to cut the line relay 11 into circuit; and a path for energizing relay 11 is completed from the two poles of the battery by wayof both windings of relay 11, both arn'iatures and front contacts of cut-in relay 10, switch springs 53 and 5% of switch 50 and their left-hand contact points, thence through the brushes 12? and 128 and line contact points of divisions and of distributor switchl) to the two limbs of the calling line, the metallic circuit of which is completed at the closed switch hook contacts at calling station A. lhis results in the operation of line relay 11. it may here be noted that the passage of the sleeve brush of division or disc 140 of the distributor switch D over sleeve terminals of lines that are busy does not result in the operation of cut-in relay 10, for the reason that a line, when connected with, has a path established from its sleeve conductor to battery, such as that by way of the resistance coil 82 of the finder circuit F, which path serves to shunt current flow from the cut-in relay 10 to such an extent so as to prevent the relays operation. Consequently the relay 11 is cut into circuit only when the distributor brushes pass over terminals of lines that are not connected with; and only in the case of a line that is not connected with or in use but which has its telephone receiver off the hook is the relay 11 operated.

When relay 11 operates it closes at its front contact an energizing circuit for the relay 12, and that relay locks up by way of a circuit that is closed through its lefthand front contact and armature, letthand switch spring and resting contact of relay 13, and right-hand switch spring and rest ing contact of relay 21 to ground. This causes av continuing energization of the relay 12 as a result of the momentary energization due to the momentary operation of relay 11 as the continually moving distributor switch brushes pass over the terminals of the calling line; and relay 12 remains energized until it has caused the operation of the line finder starting and brush tripping apparatus to bring about the extension of the calling line to the finder circuit, as will be described.

When relay 12 operates it also closes a circuit that extends from battery through the left-hand winding of the group relay 13, right-hand front contact and armature of relay 12, right-hand resting contact and switch spring oi relay 20, conductor (38, outer back contact and armature of start relay 72, and resting contact and left-hand switch spring of relay T3 to ground. This causes the operation of the group relay 13. H the common starting apparatus is not at the time in use in response to the initiation of the call in some other group the relays 72 and 73 are inert; and under these circumstances the operation of relay 12 and consequent operation of relay 13 closes a circuit that extends from battery in parallel branches through the right-hand winding of group relay 13 and winding of trip magnet 16, right-hand trout contact end armature of relay 13, conductor 65, winding of start relay T2, and resting contact. and left-hand switch spring of relay 73 to ground. The closure of this circuit locks up the group relay 13, and energizes the magnet 16 of the associated group, and

o the common start relay 72. Relay :1 operating closes a circuit th extends battery through the right-hand vindi relay 71, and the inner front contact mature of relay 72 to ground.

Relay '71 in operating closes a direct i from conductor 6t to ground by way or the left-hand switch spring and armature of relay 71. But an instant before this path is closed, the normal path from conductor 64: to ground by Way of inner back contact and armature of relay 72 is opened by the same operation of relay 7 2 that brings about the operation of relay 71. Therefore for an instant conductor 64- is entirely disconnected from ground, and during this instant 10,. the locking path for the recording group relay 12, by way of left-hand front contact and armature of relay 12 and left-hand switch spring and armature of relay 13, is opened, thus releasing relay 12. The reason for providing this alternative path to ground from conductor 64 immediately after the release of relay 12, is so that relay 12 may be in condition to respond to another calling line immediately after it has per-- formed its function of operating the starting apparatus in response to a call, and before the starting apparatus has been re leased by the starting of a finder switch, as will be described. In this way the relay 12 in effect may store and hold in readiness a succeeding call while the immediately preceding call is still occupying the starting apparatus.

When the start relay 7 2 operates, it breaks at its outer back contact the normal connection of conductor 63 with ground, thus preventing the operation of the relay 13 of any other group. It also closes a circuit for. appropriating the particular finder circuit F, F, F, which is next in order and Waiting to receive a call, and for starting the line finder switch of appropriated circuit. The energizing circuit that the start relay 72 thus closes extends from battery through the left-hand winding of finder circuit relay 33 (see Fig. 5), sequence switch contact 209 (2), conductor 76, outer front contact and armature of start relay '72, and restin contact and left-hand switch spring of relay 7 3 to ground. Relay 33 in operating closes a locking circuit for itself that extends from battery through resistance coil 36, sequence switch contacts 214 (2 to 3), right-hand winding of relay 33, sequence switch contact 213 (2 to 3), left-hand front contact and armature of relay 33, sequence switch contacts 212 (2 to 3), and armature and back contact of relay 31 to ground. Relay 33 also closes a circuit that extends from battery through the lip-drive magnet 61 of the associated line finder switch LF, c0nductor 66, sequence switch contacts 213 (2 to 3), left-hand front contact and armature of relay 33. sequence switch contacts 212 (2 to 3) and armature and back contact of relay 31 to ground. The energization of the up-drive magnet 61 as a result of the closure of this circuit starts the upward movement of the line finder shaft 1 with its sociated switch brushes and commutator brushes. Relay in operating also closes a circuit that extends from battery through the motor .i'nagnet and contact 202 oi the sequence switch 200, right-hand front contact and armature of relay 33, and sequence switch contact 210 (2 lo 5) to ground. As a result of the closure of this circuit the sequence switch moves out of position 2 and comes to rest in. position 3.

At the outset of the upward movement of the elevator shaft or rod 1 of the line tinder switch, all of the brush trip levers are moved past the corresponding trip yokes T. The only trip magnet that is energized in this case is the magnet 16 which corresponds with the group G in which the calling line is located; and consequently the only trip yoke in position to engage a trip lever on the elevator rod is the one which controls the brushes all), 11, 4-2 and 43 that are to engage the terminals of that particular group of lines. This set of brushes therefore is released ann made operative, and the other sets are held clear of their associated line terminals.

As soon as the set of brushes is tripped that corresponds with the group in which the calling line is located, the group apparatus, by means of which the lines control the brush tripping and line finder starting operations, may be returned to its normal position. This is effected by the closure of acircuit which extends from i il-Ii1-,l by Way of the winding of relay T3, conductor 77, sequence switch contacts 208 (2- to 3). conductor 69, and segment G of the line finder commutator and its correspoiuling brush to ground. is a resultof the closure of this circuit, which is timed to occur an instant after the brushes are tripped and before they engage the line terminals in the upward movement of the elevator shaft, re lay 73 is energized to open, at its left-hand switch spring and resting contort, the circuit by way of conductor (35 that up to this time has been holding energized the starting relay 72 and the trip magnet 16 and nest ciated relay l3. Relays 13 and T2 and trip magnet 16 are consequently released. liclay T3 in operating closes a circuit that extei is from battery through the lcftlu nd winding" of relay T1 and the left-hand rmature and switch spring of relay 7:) to ground. This serves to hold relay Tl. cn-- ergized after its initial energizing circuit through its right-hand winding and inner front contact and armature cit rcluv 'Z'! is broken by the release of relay T2. Consequently conductor (31 is kept grounded to ensure the maintained energizl'aation of the group relay 12 if it had stored a call while the starting apparatus was occupied with the preceding call. The stored call. h wever, does not obtain acc to the starting apparatus and the associated line tripping magnet 16 of its group until conductor 65 is again grounded; and this does not happen until relay 7 3 is released.

When relay '73 operates it also closes a locking circuit for itseli that extends trom battery through the winding and upper right-hand front contact and armature of relay 73, conductor 79, and contacts 520i" to 1) ol the series of tinder circuits to ground at the end of the series. This locking circuit is complete at this time, -for the reason that there is no tinder sequence switch resting in position 2, the sequence switch of the finder circuit that had. been resting in position 2 and was appropriated, having moved to position 3, as described, and all of the other sequence switches either resting in their normal position 1, or in some position beyond position 3. The locle ing circuit of relay 7 3 is consequently maintained until a finder switch of the series that has been resting in position 1 is moved to position 2, its waiting position. T his is efiected by means 01" a circuit that is closed by relay T3 when it operates, this circuit extending from battery through the motor magnet and contacts 206 (1.) of the SQrfllQDCB switch of the neizt finder circuit in order (assumed in this case will be tinder circuit F") that has been resting in position 1, conductor 57, contacts 206 oi the quence switch of the finder circuit F that has been appropriated, conductor 78, righthand lower front contact and armature of relay 73, conductor 79, and thence to ground by way of the series of tinder se quence switch contacts 207 (2%; to 1). The closure of this circuit moves the sequence switch t finder circuit F from its normal position i to its waiting position 2; and when this occurs the locking circuit for relay 73 of the starting apparatus is broken at sequence switch contact 207 to l) of finder circuit F and relay '73 is released. Upon the release of relay 73 ground reapplied at the'le'lfthand switch spring and back contact of that relay to

conductors

63 and 65, and the starting apparatus again lie-- comes available for respondin to a calling line, or to line whose call is stored in one of the relays 12 ot the various groups. The release of relay 73 breahs'the energizing circuit of the relay '71 by way oi the left-hand winding of that relay: and the release of relay 71 opens the path of conductor 64 directly to ground at'the armature of relay Tl and permits conductor G l again to extend to ground by way of the bacl: contact and inner armature of relay '1' 2. V

in the condition of the apparatus exist ing at this stage of the operation, the finder switch elevator is moving up with the set of brushes tripped that corresponds with the group in whlch the calling line s located, the sequence switch of finder circuit F is standing in position 3, the sequence switch of finder circuit F has been moved into its waiting position 2, and the starting apparatus has been released to render it responsive to another calling line. As the tripped brushes rise they come into engagement consecutively with the sets of terminals corresponding with the different lines of the group. At the instant oi engagement of the brush 4:2 with the corresponding line terminal 46 of each line, a circuit is closed that extends from battery by way of relay 30, sequence switch contact 217 (2 to 3), con ductor 87, brush 42, line terminal 46. conductor 83 and resistance 27 to ground. In case a line is busy either as a calling line or as a called line, a path to battery exists from conductor 83 (for instance by way oi finder circuit resistance 32 in case the line ,is busy as a calling line) that serves to shunt the relatively high resistance relay 30 and prevent its operation. If a line over the terminal of which the brushes are passing is not busy, the relay 30 is operated and in attracting its armatures closes a circuit that extends from ground through the lower winding of relay 31, inner armature and front contact of relay 30, sequence switch contact 216 (2 to 8), conductor 86, brush ll, line terminal l5, conductor 82, to one limb of the telephone line, thence by way of the path controlled in contacts of thesub-station switchhook to the other limb of the line. conductor 81, terminal a l, brush 40, conductor 85, sequence switch contact 215 (2 to 3), outer armature and frontcontact of relay 30, and upper winding of relay 31 to battery. The circuit traced above is not completed until the finder switch brushes engage the terminals of the calling line, as the calling line is the only line that has its telephone receiver oil the hook, and at the same time is not connected with either as a calling line or as a called line. The completion of this circuit energizes the relay 31 and causes that relay to interrupt at its back contact the circuit by way of the sequence switch contact 212 (2 to 3), left-hand armature and front contact of relay 33, sequence switch contacts 213 (2 to 3), and conductor 66, vhi'ch up to this time has been keeping the lip-drive magnet 61 energized and causing the upward movement of the switch brushes. Therefore the operation of the relay 31 upon the finding of the calling line acts to effect the instant deenergization of the lip-drive magnet 61 and thus to stop thebrushes on the terminals of the calling line. As the locking circuitof the relay 33 through the left-hand armature and front contact and the right-hand winding of that relay has been dependent upon the path to ground controlled in the resting contacts'of relay 31. the energization of that relay brings about the release of relay 33.

When relay 33 releases, it closes a circuit that extends from battery through the motor magnet and contact 205 of the sequence switch, right-hand back contact and armature of relay 33, and sequence switch contact 210 (2 to to ground. As a result of the closure of this circuit the sequence switch moves out of position 3 and comes to restin position 5. In moving out of position 3 the sequence switch disconnects the test relays 30 and 31 at

sequence switch contacts

215, 216 and 217 and at contact 217 to 12;) it connects the sleeve conductor 87 with battery through the resistance coil 32 in order to make the calling line busy and guard it against intrusion.

As the invention herein disclosed and claimed with the particular manner in which the connection of the calling line, after it has once been extended to a linder circuit, is further extended and completed to the line of a called subscriber, it is not thought necessary. that such part of the organization be particularly illustrated or described. The conductors of the finder circuit may be extended to the called line through the medium of the brushes or connecting device shown diagrammatically at CS, which connecting device may be operated if desired to make connection with a circuit terminating in a plug that is adapted to be inserted in a spring jack of the called line, such spring jacks being shown at 55 in association with the lines of groups G and G. It is assumed that the circuits through which connections of calling lines with called lines are extended are provided with such ordinary equipment as will enable the switchboard operator to receive the instructions from the calling subscribers, and control the apparatus involved in the completion of the connections. \Vhen the calling line has been found, as has been described, and the sequence switch moved to position 5, the next stage of the operation moves the switch out of position 5 by way of an energizing circuit for the sequence switch motor magnet completed by way of sequence switch contact 202 (5), right-hand front contact and armature of relay 33, and sequence switch contact 210 (2 to 5) to ground, the relay 33 being energized to effect this result by way of a circuit completed through its left-hand winding and sequence switch contact 209 (5 to 8). In succeeding stages of the operation the sequence switch 200 is moved out of positions 6 and 7 by way of circuits completed first through sequence switch contact 203- (6) and then through sequence switch contact 203 ('7) and a subsequent ener 'ization of relay 33 over the circuit extending through the left-hand winding of that relay and sequenceswitch contact 209 to 8) closes an energizing circuit for the sequence switch motor magnet by way of contact 202 (8) right-hand front contact and armature of relay 33, and sequence switch contact 210 ('7 to 10), that moves the sequence switch out of position 8. The sequcnce switch thereupon moves to its talking position 14-, in which position the talking

conductors

85 and 86 are extended through by way of sequence switch contacts 215 (8 to 1 1) and 216 (8% to 111-), while the sleeve conductor 87 is extended through by way of sequence switch contact 217 (12 to 141:), right-hand winding of relay 33, sequence switch contacts 211 (12 7 to 1 1), the third brush from the top of the connecting device CS, switch 58 that at this time is closed, and resistance coil 59 to battery. As long as the talking condition continues, current flows over the above-traced sleeve conductor circuit to ground by way of resistance coil 27 of the calling line, and keeps relay 33 energized. At the end of the conversation, switch 58 is moved to open the sleeve conductor circuit, and the consequent release of relay 33 closes a circuit that extends from battery through the motor magnet contact 202 (1st of the sequence switch, left-hand back contact and armature of relay 33, and sequence switch contact 211 (14c) to ground. hen the sequence switch reaches position 15 it is moved through this position by the circuit tor its motor magnet closed by way of contact 205 (15), right-hand back contact and armature of relay 33, and sequence switch contact 210 (15) to ground. hen the sequence switch reaches position 16 a circuit is closed that extends from battery through the down-drive magnet 62 of the line finder switch, conductor 67, and sequence switch contact 210 (16) to ground. Upon the return of the line finder switch to its normal position a circuit is closed that extends from battery through the motor magnet and contact 204 (16) of the sequence switch, conductor 68, and segment Y oi. the line finder commutator and corresponding brush to ground. The sequence switch is moved out of position 17 by a circuit subsequently completed for its motor magnet by way of sequence switch contact 204 (17) and thereupon the sequence switch continues its movement until it comes to rest in its normal position 1, out oi which it may be moved into its waiting position 2 in the manner hereinbefore described.

The foregoing description will serve to make clear some of the more relevant characteristics of a call distributing system of the type in connection with which the present invention is particularly designed to be used and to show the manner in which the particular features of the invention as subsequently claimed cooperate with the rest of the organization in such a call distributing system. It may be seen from the foregoing that the response of the circuit extending "neonate of lines in case the normal testing apparatus is not operating properly, will now" be specifically described. 3

The organization of the system is such that the relays 10 and 11, which test the lines of each group for the presence of the calling condition on any of them, are also utilized for making a special test once in each cycle of operation of the distributor switch, and, pursuant to this test, for controlling certain emergency or periodical test apparatus. Taking for example the operation of the distributor switch D; at the beginning of each cycle; of operation of that switch in testing a group of lines, a circuit is closed that extends from battery through the resistance coil 56, switch spring 51 and lefthand contact of the switch 50, stationary brush 121 of the disc or division 130 of the distributor switch 1) and the commutator segment with which that brush has just come into engagement, rotating brush 125, contact 131, right-hand winding of relay 20, left-hand restin contact and switch spring of relay 21,.left-hand back contact and armature of relay 12, switch spring and resting contact of relay 13, and righthand switch spring and resting contact of relay 21 to ground. If immediately before this circuit is closed at brush 125 and contact 131 the engagement of the terminals of a calling line has caused the locking up of relay 12 to store a call in that relay for subsequent transmission to the starting apparatus, or if relay 13 of the group is still held energized as the result of an immediately preceding call still occupying the starting circuit, the path above traced will be open at either the left-hand back con tact of relay 12 or the left-hand. resting contact of relay 13, or at both places, and the relay 20 will not be energized. But if the

relays

12 and 13 of the associated group are not thus engaged by a previously encountered call, the relay 20 will operate the instant distributor brush 125 encounters test contact 131. It may here be noted that, referring to Fig. 1, the interval or space between the test contact 131 and the last preceding line contacts of

discs

140, 150 and 160 is made suflicient so that in the normal operation of the system if the

relays

12 and 13 have been operated as the result of a call picked up on the last line of the group,

there will have beentime' for them torelease before the test circuit is closed by the engagement of the brush with test contact 131.

Relay'20 in operating closes a circuit extending from battery through the left-hand winding of relay 20 and the winding of relay 21 in parallel branches, thence through the left-hand front contact and armature of relay 20, and the back contact and" arma 'ture of relay 23 to ground. The closureof this circuit operates relay 2.1 and locks up relay 20.

1n. the normal calling line testing operation, relay 12 in operating operates the as" sociated relay 13 andalso interrupts the extension of conductor 63 to the

relays

12 and 13 of other groups so as to prevent other groups from having control over the starting circuit. But in making the special or periodical test, it is desirable that relay 12 shall neither operate the associated group relay 13 nor interrupt conductor 63 to disconnect the other groups fromthe starting apparatus. Therefore the system is arranged so that relay 20 in operating to prepare the way for the periodical test, breaks at its right-hand switch and resting contact the connection of conductor 63 with the right-hand armature of relay 12, thus preventing the immediately subsequent operation of relay 12, from actuating relay 13; and so that the relay 20 in operating closes at its right-hand switch spring and armature a direct connection of the conductor 63 with the continuation of that conductor leading to the other groups of the series. Relay 21 in operating, as a result of the closure of test contact 131 of the distributor switch, substitutes: the upper winding of relay 22 for the right-hand winding of relay 20 in the conducting path that is normally closed at the. left-hand back contact and armature of relay 12 and the left-hand switch spring and back contact of relay 13. By this operation of relay 21 the energization of relay 22 in a succeeding'stage of the periodical testing operation is placed under the control of the above-mentioned circuit leading through the normal resting contacts of

relays

12 and 13, just as the energization of the relay 20 was under the control of the circuit leading through these contacts in the first stage of the periodical test.

Immediately after the above described preparatory operation, the brushes 126,127 and 128 of the distributor switch engage. the

test ing contacts

141, 151 and 161, respectively. As a result of the engagement of the brush 126 with test contact 141, a circuit is completed for the energization of the cut-in relay 10 by way of the path to ground from contact 141 through resistance coil 24; and as a result of the engagement of brushes 12'Zand 128 with

contacts

151 and 161, a.

circuit is completed for the energization of the line relay 12 by way of the resistance coil 25 that bridges

contacts

151 and 161, the.

line relay 11 having been cut into circuit by the operation'of the cut-in relay 10. Line relay 11 in operating closes at its front contact and armature the energizing circuit for relay .12, and relay 12 in operating closes a locking circuit for itself that extends by way of its left-hand front contact and armature, left-hand switch spring and resting contact 'of relay 13, right-hand switch spring and armature of relay 21, and back contact and a circuit that extends from battery through resistance coil 56, lever 51 and associated left-hand contact of switch 50, brushes 121 and 125 of the distributor switch, test con- .tact 132, upper winding of relay 22, lefthand armature and switch spring of relay 21 and thence to the left-hand back contact of relay 12. If the apparatus is functioning properly, the relay 12 has operated, as described, and the conducting path is open at this point. If the apparatus has failed to function properly the relay 12 has been. left inert, and the conducting path is continued by way of the left-hand armature of relay 12, left-hand switch spring and resting contact of relay 13, right-hand switch spring and armature of relay 21, and back contact and armature of relay'23 to ground. Under these circumstances therefore relay 22 is energized and closes a locking circuit for itself that extends from battery through the common alarm relay 7 1, conductor 48, emergency lamp 26 of the associated group, lower winding and front contact and armature of relay 22, conductor 49, and lever and resting contact of release .key 7 5 to ground. The closure of this 0111311113 energized relay 74, which closes at its armatureand front contact a circuit that causes the ringing of the alarm are consequently released and restore to normal the circuits that they control. As the locking circuit of relay 12 also includes the resting contacts of relay 23, the operation of 23 effects the release of relay 12. The distributor circuits are thus returned to their normal condition, so that they are in readi ness to respond to the calling line test, which is taken up by the distributor switch brushes immediately after testing contact 133 is passed over. But relay 22 remains locked up, and continues to cause the ringing of the alarm bell and the illumination of the group emergency lamp 26 until the attendant has taken appropriate action and has op cratcd the release key 75.

hen the distributor switch fails to operate properly, the operation of the emergency signal apparatus informs the attendant that action must be taken in order to prevent calls in the group served by the dicating that the testing paths by way of distributor switch D are not operating properly, the attendant actuates the switch 50 to throw its levers 51, 53 and to the right. This act instantly connects the group and periodical testing apparatus of line group G with distributor switch D and disconnects the apparatus from distributor switch D. As a result, the distributor switch D is relieved of its functions, and may then be stoppedby throwing the lever 137 (see Fig. 1) so as to disengage the clutch members. Such adjustments or repairs as may be necessary to make it again operative may then be made. As the distributor switch D, as illustrated in the drawing, is normally making the tests for the group G of telephone lines, the throwing of the switch 50 to the right, with the consequent shifting to the distributor switch D of the group and periodical testing circuits of group G of telephone lines, causes the distributor switch D to make the tests for all of the lines of both line groups G and G. In like manner, if it should be the emergency lamp 26 that was lighted upon the ringing of common alarm bell 80, this would indicate that the trouble was in the distributor switch D, and the attendant, by throwing switch 50 to the left, would transfer the load, or work of testing the fifi ' alternative testing switch for the line group that the other switch of the pair normally serves.

The terminals of each of the'two groups of lines served by each distributor switch are being continuously passed over by one or the other of the two sets of travelling brushes of the switch; but normally these brushes are connected with the external group testing circuit only while they are passing over the terminals of one of the groups of lines that the switch is adapted to serve- As described, all that is necessary in order to make the single distributor switch serve as a testing switch for both groups of lines, is to throw the switch or 50 so as to connect the travelling brushes of the distributor switch with the external group testing circuit of one group during halfof their rotation and with the external group testing circuit of the other group during the other half ot'their rotation. Each g"oup testing circuit has symmetrical connections with the test terminals and the brushes of the two distributor switches that serve the associated group of lines.

o A separate set of resistance coils, 24, 25, and

' 8e, 35, respectively, is shown as being connected with the test terminals of each of the distributor switches that serve a particular group of lines; but if desired one of these sets of resistance coils, as for instance the

set

84, 35, may be dispensed with and the

set

24, 25, may have multiple connections with corresponding terminals of both switches D and D.

What is claimed is:

1. The combination with telephone lines divided into groups, of finder switches for connecting with calling lines of said groups, a distributor switch and associated starting mechanism for starting one of said tinder switches, and means for bringing said distributor switch at will into operative relation with one or another or a plurality of said line groups.

2. The combination with a plurality of lines divided into groups, of switching mechanism for extending the circuits of calling lines of said groups, a distributor switch for controlling the operation of said switching mechanism, and means for bringing said distributor switch into operative relation with the lines of one or another or a plurality of said line groups.

3. The combination with a plurality of telephone lines divided into groups, of

-"s'witchi.ng mechanism for extending the cirtributor switch normally associated with each of said line groups and controlling the response of said. switching mechanism to a calling line of the associated group, and means for bringing each of said distributor switches into operative relation with the lines oi another of said line groups.

4. The combination with a plurality oi groups of telephone lines, of a plurality of finder switches for making connection therewith, starting apparatus for said finder switches, group apparatus for eachof said line groups, a plurality of dis tributor switches each adapted to serve a plurality of line groups, and means for bringing the group apparatus of any line group into operative relation with that line group through the medium of one or another of said distributor switches.

5. The combination with a group of telephone lines, of a plurality of finder switches for making connection with the lines of said group, starting apparatus for controlling the starting oi? one of said finder switches, group apparatus for controlling said starting apparatus, a plurality of distributor switches, and means for bringing said group apparatus into operative relation with said line group through the medium of one or another of said distributor switches.

The combination with two groups of telephone lines, of two testing switches each of which is arranged normally to test the lines of a different one of said groups and is adapted also to test the lines of the other group, means for making either of said testing switches operative to test the lines of both groups, and line circuit extending switches automatically operative responsive to the test oi said testing switches.

'7. The combination with a plurality of groups of telephone lines, of a plurality of multiple brush finder switches for making connection with the lines of said groups, starting apparatus for said finder switches, group apparatus for each line group, means actuated by said group apparatus to opcrate said starting apparatus and to render operative an associated set of brushes of the started one of said finder switches, a plurality of testing switches for testing the lines of said line groups, and means for bringing the group apparatus of any line group into operative relation with the associated line group through the medium of one or another of said testing switches.

S. The combination with a group of telephone lines, of a distributor switch having sets of terminals to which the lines of said group are connected, means made operative when said distributor switch engages the terminals of a calling line for extending the connection of said line, test terminals on said distributor switch periodically engaged by said switch, and signal means controlled by the engagement of said switch with said test terminals.

9. The combination with a group of telehone lines, of a continually operating test- 'ng switch having terminals to which the s of said group are respectively con cted, means made operative upon the eniagcn'ient of said switch with the terminals a calling line to extend the. connection of aid line, an artificial calling line having ierminals on said switch, and testing apparatus controlled by the engagement of said switch terminals of said with the artificial calling line.

it), The combination with a group of telephone lines, of a continually operating testing switch having terminals to which said lines are respectively connected, means made operative upon the engagement of said switch with the terminals of a calling line to extend the connection of said line, periodical testing means associated with said testing switch, and a signal device controlled by said periodical testing means.

11. The combination with a group of telephone lines, of a testing switch having ter minals to which said lines are respectively connected, means for extending the circuits of said lines, arelay responsive to the engagement of the terminal of a calling line by said testing switch for operating said circuit-extending means, test terminals on said testing switch to the engagement with which by said testing switch said relay is also responsive, and signal apparatus operated by the failure of said relay to respond to the engagement of said switch with said test terminals.

12. The combination with a group of telephone lines, of a distributor switch having terminals with which said lines are respectively connected, test terminals on said distributor switch, switching mechanism for connecting with any of said telephone lines, a signal device, a relay responsive to the engagement of said distributor switch with the terminals of a calling line and to the engagement of said switch with said test terminals, and means for bringing said relay alternatively into controlling relation with said switching mechanism and with said signal device.

13. The combination with a group of telephone lines, of a testing switch having terminals to which the lines of said group are respectively connected, switching mechanism for establishing connection with said lines, a signal device, test terminals upon said, testing switch, and apparatus associated with said testing switch responsive to the engagement of said switch with the terminals of a calling line and with said test terminals, and means for bringing said apparatus alternatively into controlling relation with said switching mechanism and said signal device.

14. The combination with a plurality of telephone lines, of a testing switch to terminals of which said lines are respectively connected, switching mechanism for completing connection with any one of said lines, a signal device, testing mechanism associated with said testing switch for periodically testing the operation of said switch, apparatus associated with said testing switch and adapted when operated to render operative said switching mechanism, and

'means associated with said testing switch and controlled by said apparatus for rendering inoperative said periodical testing means when said apparatus is operated to render operative said switching mechanism.

15. The combination with a group of telephone lines, of a distributor switch to terminals of which said lines are respectively connected, switching mechanism for making connection with any of said lines, apparatus associated with said distributor switch and adapted when operated to render operative said switching mechanism, periodical testing means associated with said distributor switch, and means for rendering inoperative said periodical testing means when said apparatus is in its operated condition.

16. The combination with a plurality of groups o'f'telephone lines, of a plurality of finder switches for making connection there with, a distributor switch for each of said groups of telephone lines to terminals of which said lines are respectively connected, group apparatus for each of said groups under the control of the associated distributor switch, common starting apparatus for said finder switches actuated by the operation of any of said group apparatuses, means operated in the operation of any of said group apparatuses to prevent the operation of any other of said group apparatuses, periodical testing means associated with each distributor switch and operating through the medium of the associated group apparatus, and means for preventing the operation of any of said group apparatuses by the associated periodical testing means from operating said common starting apparatus and from interfering with the operation of said common starting apparatus by any other of said group apparatuses.

17. The combination with a group of tclephone lines, of a plurality of finder switches for making connection therewith, a distributor switch to terminals of which said lines are respectively connected, group apparatus under the control of said distributor switch, starting apparatus for said finder switches actuated by the operation of said group apparatus, periodical testing means associated with said distributor switch and operating through the medium of the associated group apparatus, and means for preventing the operation of said group apparatus by the associated periodical testing means from operating said common starting apparatus.

18. The combination with a plurality of groups of telephone lines, of a plurality of distributor switches to terminals of which said lines are respectively connected, a plurality of finder switches for making connections with said lines, a common starting apparatus for said finder switches, group apparatus for each line group adapted when operated to operate said common starting apparatus, a signal device, periodical testing means associated with each distributor switch for controlling said signal device through. the medium of the group apparatus of the associated group, means operated in the operation of each group apparatus for preventingany other group apparatus from operating said common starting apparatus,

and means for rendering inoperative said preventing means of any group during the operation of said periodical testing means of that group.

In witness whereof, I hereunto subscribe my name this 20th day of October A. D.,

SAMUEL B. WILLIAMS, JR.