US1173560A - Semi-automatic telephone-exchange system. - Google Patents

Description

H. P. CLAUSEN.

SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED IULY 6.,1914.

1,173,560. I. Patented Feb. 29,1916.

2 SHEETS-SHEET l.

H. P. CLAUSEN.

SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED JULY 6.1914.

1,173,560. PafentedFeb. 29, 1916.

- 2 SHEETS-SHEET 2. Hg. 2.

W/f/vessesx //7 van for:

@3 m Henry F C/awen.

HENRY PETER CLAUSEN, or

mounrvnanon, New YORK, assrenon, BY MESNE ASSIGNMENTS, TO'WESTEBN ELECTRIC COMPANY, INCORPORATED, A CORPORA- TION OF 'NEW YORK.

SEMI-AUTOMATIC 'rnnnrnonn-nxennnen SYSTEM.

Specification of Letters Patent.

Patented Feb. 29, 1916.

Applicationjiled July 6, 1914. Serial No. 849,219.

To all whom it may concern:

Be it known that I, HENRY PETER OLAUSEN, a citizen of the United States, residing at Mount Vernon, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Semi-Automatic Telephone-Exchange Systems, of which the following is a full, clear,'concise, and exact description.

This invention relates to a semi-automatic telephone exchange system, and particularly to the provision of means to obtain a reverting busy test without at any time removing the busy potential from the calling line test terminals. For this purpose means are provided which permit the seizing of the line in spite of the busy test potential existing on the test terminals.

Another feature of the invention provides for the disconnection of the answering end of the cord circuit on all reverting connections before the signaling current for the desired party on the calling subscribers line is projected out over the circuit.

A further feature of this invention provides means whereby an operator may seize a busy line, disregarding the busy test, for

connections other than reverting calls. Conditions warranting this would arise when at any time an operator receives speclal mstructions to connect to a line circuit regardless of the busy test condition maintained on the test terminals 6f the circuit. This feature is' of particular value when used in connection with the circuits of the recording operators of a toll system, as it is necessary that the recording operators be able to seize a line that has been rendered busy by a connection that has been established at the local board.

Other features of the invention will become apparent from time to tlme from the following description and the appended claims. a

This invention may be adapted to various types of telephone systems, but the present embodiment is especially designed for use in semi-automatic systems wherein sending apparatus is located at'the central oflice, and arranged for actuation by an operator in accordance with the instructions received from the calling'subscriber. In such systems, the initial connection with the calling line may be made by, any suitable means,

but in the system herein disclosed this connection, is made by the operator by the insertion of the plug at the answering end of the cord circuit into the jack of the calling hne. Each cord or connecting circuit ter- Inmates at one end in a cord and plug, and at the other end in a selector or connector switch. To simplify the drawing and the following description no selector switches have been shown, but to any one skilled in.

the art, it will be apparent that selector switches can very readily be inserted between the operators controlling apparatus and the connector switch without affecting the operation of the system. The sending mechanism, which is located at the central oflice, is temporarily associated with the cord circuit while the connection is being established, and serves to control the operation of the selector switches, not shown, and the connector switch.

The invention is illustrated in the accompanying drawings in which- Figure 1 illustrates the specific embodiment of the connecting or cord circuit and an associated line circuit; Fig. 2 shows theoretically the connections to the test' or sleeve conductor when the connector switch is testing an idle line circuit; Fig. 3 shows these connections when testing a busy line circuit; and Fig. fl: illustrates these connec tions for a reverting test.

The sending mechanism located at the central office is shown in conventional form in the drawing. Any type of sending mechamsm can be used for this purpose, the simplified form here shown being used merely to avoid complications. The sending mechamsm consists of a circular plate 30 rotatable about an axis 31. On the plate 30 is mounted an arm 32 and the springs 33- and 34. The arm 32 may be rotated a slight distance to the right independently of the plate 30, this movement being controlled ing by a long contact.

moving the arm 32 and the plate 30 to the right.

Mounted below the plate 30 is a stationary plate 8? bearing the numerals 0 to 9 inclusive. These numerals serve to indicate the amount of movement which is to be given to the plate 30 for the production of the desired number of current impulses which are required to move the automatic switches to the desired position. The sending mechanism is equipped With a spring 38 provided with a roller bearing which normally rides in a notch in the plate 30. Whenever the plate 30 is displaced from normal, the roller rides on the outer edge of the plate 30 and causes the spring 38 to connect with contact 39. A part of the circumference of the plate 30 contains ten teeth on .which rides a roller attached to a spring 40. The spring 40 will intermittently engage the contact 41 as the roller rides over the top portion of each tooth.

The controlling circuits associated with the various parts, of the connecting circuit, which must be established ina definite order at successive stages of the operation of the system to bring the various devices or arts into operation as required, are established by automatic. switching mechanisms which are called sequence switches. Qne of these sequence switches is associated with each connecting circuit. Each of these sequence switches consists briefly of a plurality of circuit changing contacts adapted to be operated in a definite sequence. The particular structure is unimportant for the purposes of the present invention, but a satisfactory type is conventionally illustrated as consisting of a plurality of rotating disks or wipers which are represented in the draw- A plurality of springs or brushes are provided for engagement with each pair of conducting disks.

In the following description of the system the brushes or springs, which cooperate with each plate, will be referred to as contacts 1, 2, 3 and 4, representing respectively the upper left-hand, the upper right-hand, the lower left-hand and the lower righthand contacts. By means of these brushes and a proper cutting away and arrangement of the conducting plates on the insulating disk, any two or more brushes arranged for engagement therewith may be electrically united at any stage of rotation of the shaft. The sequence switch positions, at which the various springs or brushes are in engagement with the rotatable disk, are indicated by numerals placed adjacent to the several contacts respectively. Motor mechanism is provided for rotating the shaft in its. successive step-by-step movement. These mechanisms, in the embodiment herein shown, comprise continuously rotating friction disks 42. The rotatable shaft of each sequence switch is provided with a cooperating friction disk 43, and an electromagnet is provided for causing effective engagement of the friction disks whereby the switch shaft may be rotated. Each sequence switch is provided with a specialcontact A. The numerals, appearing adjacent to this contact, represent the only positions in which it is open, and consequently the only positions at which the'sequence switch can stop.

The operation of the system will now be described in detail in connection with the accompanying drawings.

When the subscriber removes his receiver from the hook he will close the subscribers line loop and thereby operate line relay 1. The operation of this relay will display the line signal 2, and the operator upon seeing this signal will plug into the line jack. The act of plugging in the line jack will complete a circuit from the ground at the cut-ofi relay 4 by way of the sleeve of jack, and the sleeve of the plug employed, through the sequence switch contact R and relay 5 to battery. This will cause the operation of the cut-oil relay 4, which will extinguish the line signal. The operation of relay 5 will complete a circuit from the ground on the left-hand armature 3 of res. lay 6 to the left-hand armature of relay 5, through contact 3 of sequence switch, spring B to the sequence switch magnet and battery. The sequence switch will consequently move to its second-position. In the second position of the sequence switch a circuit is completed from the ground at the cut-ofi relay 4, over the test conductor of the line and cord to switching relay 24, and thence by way of contacts 3 and 4 of sequence switch spring Q, to coil 25 and battery. This will energize relay 24. The operation of relay 5 will also close a circuit from the ground on right-hand armature 2 of relay 5, through the resistance coil 7 and the supervisory lamp 11 to battery. In position 2 of the sequence switch a circuit will be completed from the ground at sequence switch spring D, through contact 1 to the repeating coil winding 8, and then by way of the tip of the cord and line to the subscriber desires connection with subscriber #64. The operator will consequently move the arm 32 of her sending mechanism to numeral 6 on the indicating plate and then .move to its fourth position.

release the same. In moving the arm to the right the contact between springs 33 and 34 will be opened, but as soon as the operator releases this arm, it will return to its normal position and close a contact between these two springs. lVhen the plate 30 of the sending mechanism is displaced from normal. a circuit is completed from battery, through relay 13, sequence switch spring (7, springs 39 and 38, left-hand armature of relay 5, left-hand armature 3 of relay 6, to ground. This will operate relay 13, which completes a circuit from the ground on the armature of relay 13, through sequence switch contact 1 of spring E. and the sequence switch operating magnet to battery. The sequence switch will consequently mOVe into its 3rd position. The plate 30, in returning to its normal position, will cause the roller 40 to ride over six of the teeth placed on the outer edge of the plate 30, and consequently six intermittent connections will be made between springs s0 and ll. These intermittent contacts will close a circuit from battery, through the vertical magnet 12, contact 4 of sequence switch spring N, contacts 2 and 1 of sequence spring H, springs 33 and 34:, springs 40 and 4:1, left-hand armature of relay 5 and left-hand armature 3 of relay 6, to ground. The vertical magnet will consequently be attracted six times and will therefore raise the selector shaft to a position opposite the sixth row or" contacts. When the plate 30 returns to normal, the connection between springs 38 and 39 will be opened. This will deenergize relay 13, and a circuit will be established from ground on the armature or" this relay by way of contact 3 of sequence switch spring E, to the sequence switch operating magnet and battery. The sequence switch will therefore The operator next moves the arm 32 to numeral 4: on the indicating plate of the sender. This will again energize relay l3, and a. circuit will be established from ground on the armature of this relay by way of contact 1 of sequence switch spring E, through the sequence switch operating magnet, to battery. The sequence switch willconsequently move to its fifth position. A circuit is now completed from battery, through the rotary magnet 14. contact 3 of sequence switch spring N, contacts 2 and at of sequence switch spring H, springs 33 and 34, springs 40 and 41, the left-hand armature of relay 5, the left-hand armature 3 of relay 6, to ground. The return of the plate 30 from its displaced position to normal will cause the repeated energization and deenergization of the rotary magnet, due to the intermittent making and breaking of the circuit just traced at the contacts 40 and 41, and the selector switch contacts will be moved so as to rest on the contact terminals of the subscribers line desired.

A circuit will now be completed from the ground on the cut-off relay of the called subscribers line, by way of the test terminal to the selector test Wiper l5, and thence over contacts 1 and 4 of sequence switch spring L, through the windings of relay 16 in series and sequence switch spring M, to battery. This circuit will be closed, due to the fact that the-sequence switch moved through its sixth position, when the plate 30 of the sending mechanism returned to its normal position, and opened the connection between spring 38 and contact 39, thus releasingrelayl3. This completed a circuit from ground, on the armature of relay 13, through contact 3 of sequence switch spring E, to and through the sequence switch operating magnet to battery, thus moving it from the fifth through'the sixth position and into the seventh position. The completion of the circuit over the test terminal caused the operation of relay l6. Relay 16 has a two winding, the right-hand winding being wound to a high resistance and the left-hand winding being wound to a comparatively low resistance. Upon the operation of relay 16, the high wound right-hand winding is short-circuited and the relay is locked up by means of the lefthand low wound winding. The application of battery, through the two windings of relay 16 to a test terminal, does not place the busy test on this terminal, due to the reduction of the battery potential by the high wound right-hand winding. However, when this winding is short-circuited, due to the operation of the relay, the battery is applied directly to the test terminal through the lefthand low-wound winding only, and this maintains the busy test potential on the test terminal of the line.

A theoretical circuit or" the test or sleeve conductor, when the sequence switch is in position 7 and for the conditions just described, is illustrated in Fig. 2. The operation of the various relays, that constitute a part of the test connection, will be more easily appreciated by reference to this circuit. Thus, when the sequence switch is passing through position 6, sequence switch spring K is open and the test relay 16 will receive full battery potential through the cut-0H relay 4. The test relay will consequently be energized and short circuit its high resistance winding before the contact at sequence switch spring K is closed. /Vhen this contact is closed in position 7, switching relay 24 will remain energized. A flow of current is maintained through this relay, in spite of the fall of potential at its winding terminals, which is large enough to hold up the armature of the operated relay, but

insufficient to cause its initial actuation.

lua

This relay must be maintained in its actuated position to prevent a false reverting busy signal. The operation of this busy test will be more fully explained herein- 5 after; for the present it will be assumed that the called subscriber is not busy.

When the sequence switch moves into its seventh position, a circuit will be completed from battery through calling supervisory lamp '20, resistance coil 21 and contact 2 of sequence switch spring D, to ground. This will light the calling supervisory lamp. The operation of relay 16 will close a circuit from the ground on the left-hand armature of relay 16, to contact 3 of sequence switch spring J, contacts 2 and 4 of sequence switch spring P, through the operating magnet of the sequence switch, to battery. The sequence switch will consequently move into 20 its 8th position. and will continue to move into its 9th position, due to a circuit which can be tracedfrom the ground on the left hand armature of relay 22, through contact 2 of sequence switch spring B and the operating magnet of the sequence switch, to

battery. In position 9 of the sequence switch, the connecting circuit to the calling subscriber is closed at sequence switch springs J and N, and the operator is therefore in a position to ring the desired subscriber. This ringing circuit may be traced from the generator current on the tip side of the ringing key, through contacts 1 and 2 of sequence switch spring P, contact 4 of sequence switch spring J, to the selector switch wiper and contact to the tip side of the line, returning by way of the ring side of the line, the selector sw1tch-w1per,

contact 2 of sequence switch spring lfl, con- 7 tacts 2 and 1 of sequence switch spr ng Q,

to the ground onthe ring side of the ringing key.

' \Vhen the subscriber answers, he will close the subscribers line loop, and battery will be fed out on the line through the calling supervisory relay 23.

0 removal of this plug will open the circuit of relay 5, and it will consequently be deenergized, closing a circuit from ground on left-hand armature 3 of relay 6, through the left-hand armature of relay 5, contact 1 of sequence switch spring B, to and through to battery.

.scribers line.

the operating magnet of the sequence switch. Contact 1 of sequence switch spring B is closed in positions 2 to 18, and therefore the sequence switch will. continue to revolve until it reaches its first or normal position. In passing through its 16th position a circuit will be closed from ground, through contacts 3 and 2 of sequence switch spring L, to and through a release magnet 29, to battery. The operation of the release magnet 29 will return the connector switch to its normal position, and since the sequence switch has also moved to its first position all the apparatus in the circuit will have returned to normal.

It will now be assumed that the party desired is busy. In this case it will be necessary to note that when the o erator plugs into the jack of the calling ine, a circuit will be completed from the ground of the cut-01f relay, over the sleeve of the line and cord, through relay 24, contacts 3 and 4 of sequence switch spring Q and resistance coil Contacts 3 and 4 of sequence switch spring Q are closed in positions 2 to 7. Therefore switching relay 24 is energized immediately after the plug is inserted in the line jack and the sequence switch is moved out of its normal position. Consequently the core of relay 24 will be thoroughly saturated when the sequence switch reaches position 7, and relay 24 will remain energized when a busy line, not of the reverting kind, is being tested, notwithstanding the reduced flow of current due to the shunting action of line and cord connected to the busy terminals. This will be more fully explained hereinafter. 1

When the operator, in response to the request from the calling subscriber, has stepped the selector wipers to the terminals of the desired line, which in this case is assumed to be busy, a circuit will be completed from battery, through sequence switch spring M, relay 16 contacts 4 and 1 of sequence switch spring ll, to the test contact, connected in multiple to similar contacts of other switches and associated with the line contacts of the desired busy sub- However, as the line is busy, a relay, similar to relay 16 of another connecting circuit, will be connected to the test contact of this particular line, and as said relay will be operated the high resistance winding of the relay will be short circuited. Therefore, when the test wiper of the present connection is switched on to this test contact, the relay 16 of this connecting circuit will not operate because of the high re sistance of the right-hand winding of this relay the relay being so proportioned that it will not receive suflicient current to cause its actuation when connected in multiple with a similar relay, in which the high resistance winding has been short-circuited, or

when connected in multiple with low wound sleeve relay 5 of a busy line. Relay 16 of the connecting circuit, which is switched to the busy line, will therefore not operate; A. circuit I will be completed, however, from battery, through interrupter 26, resistance coil 27, sequence switch spring F '(it being remembered that the sequence switch isat this time in its seventh pesition), armature of relay 24,- resistance 28 and calling supervisory lamp 20, to battery. As previously stated, relay 24: is operated as soon as the sequence switch moves to its-second position. W hen the sequence switch moves into its seventh position, relay 24 is shunted bya circuit containing sleeve relay .5 and resistance coil 50 in series, sequence switch it being open in the seventh position. it is likewise shunted by the cut-off relay 4 of the line-connectcd to the busy test terminal. Due to these shunt circuits, the flow of current through relay 24 will be materially. de-

creased, but since the relay core is magnetically saturated, suilicient current will continue to flow through the coil of the relay to maintain it in its operated position; The function or" coil 50 is to increase the resist ance of the shunt circuit, containing relay 5, by an amount sullicient to-raise the complete resistance of this shunt circuit to a value which would allow enough current to traverse the winding of relay 2%"to maintain it in its actuated position. The coil 50 is likewise given a resistance low enough so that the path from battery over the parallel circuit, consisting of the two branches containing respectively the coil 25 and the relay 24, and the relay 5 and the coil 50, will have a resistance high enough to reduce the potential on the sleeve or test conductor of the calling line to a value suiliciently low to prevent the actuation of relay 16 of any other connecting circuit which maybe switched "to the multiple terininals'of thisli'ne. These .circuit conditions are shown theoretically in Fig. 3. Whenever the sequence switch steps into'its seventh position, calling supervisory lamp 20 will be lighted, and the closing. of

the circuit just traced, due to the action of the interruptenwill periodically shunt out calling supervisory lamp 20 at a predeter mined rate, and thus indicate to the operator that the line desired is busy. The operator may now inform the calling subscriber that the line is busy and take down the connection and restore the apparatus to normal, as previously described, or if so desired, she may seize a busy line in spite of the busy condition maintained on the test terminal of the line.

If the operator desires to obtain connection with the busy line, she will operate key 44:. This will complete a circuit from ground on the make contact of the key, to sequence switch spring S, and thence through the operating magnet of the sequence switch, tobattery. The sequence switch will therefore move to its eighth position. In this position a circuit will be completed from battery, through resistance coil 48,-contact of key as, contacts 3 and 2 of sequence switch spring H, contact 3 of sequence switch spring K, to the high resistance winding of relay 16. This will shunt out this high resistance winding and the circuit just traced may be continued throughthe low resistance winding of relay 16, contacts 4: and 1' of sequence switch L, to. the test wiper of the connector switch and the ground at the-cutofi relay. As the high resistance winding of relay 16 is now short-circuited, this relay will receive enough current for its actuation, which will cause the sequence switch to move into its ninth position, as previously described in connection with the non-busy line. A simplified circuit, showing the elec trical connections for forcing the operation of the test relay 16, is shown in dotted line in Fig. 3. The connectingcircuits for the subscribers, and the circuits employed in restoring the apparatus to itsnormal position, are the same for a connection of this type as those described in connection with the nonbusy subscriber.

When the subscriber has been informed by the operator that the party desired is busy, the subscriber may request a connection with another subscriber. In this case the operator will not remove her plug from the calling line jack, but it'is obvious that it will be necessary to restore the switchingv apparatus to normal before connection with another subscriber can be made. This is accomplished by the operator by the actuation of key 51. The operation ofthis hey completes a circuit from the ground on the make contact of the key, to and through relay 6, to battery. Relay 6 will consequently be energized and will be looked over a circuit which may be traced from battery, through relay 6, the make contact and righthand armature of relay 6, contact 3 of sequence switch spring D, to ground. Contact 3 of sequence switchDis closed in positions2 to 18, and consequently relay 6 will be locked up until the sequence switch returns to its normal position. The attraction of lefthand armature 3 of relay 6 closes a circuit from ground, through its armature and make contact and the-operating magnet or" the sequence switch, to battery, and since the relay is locked up for positions 2 to 18,

the sequence switch will continue to revolve until it reaches its first position. It consequently becomes evident thatthe operator may wipe out a connection at any stage of the connection except when the sequence switch is in position 1. When the sequence switch returns to position 1, it will continue to revolve to position 2 because of the oper ation of the sleeve relay 5, which is actuated because the cord of the connecting circuit is connected to the line jack of the calling subscriber. V

For the purpose of preventing lnterf erence by the manipulation of the sending apparatus, during the period in which the sequence switch is returning to normal, the ground of the impulse sending circuit is broken at armature 3 of relay 6. Consequently, the sendin circuit will be open until the relay 6 is energized, which will not occur until the sequence switch .has returned to its first position.

Whenever a subscriber desires a connection on a recall, or under the circumstances just explained the wipe-out operation is accomplished without openingjthe tip or ring side of the cord circuit, the cord circuit being normally 0 en' in position- 1' at sequence switch springs C and D. Since, in

a complete rotation of the sequence switch, it Wlll become necessary to pass by position 1, the circuit to the calling subscriber would ordinarily be opened at sequence switch springs C and D, and thus cause an undesirable noise in the receiver "of the calling subscriber. This is prevented by shunt circuits which are maintained about these contacts, the shunt circuit about sequence switch spring C being traceable from the contact 1 of sequence switch spring Q, through righthand armature 1 of relay 5, left-handarmature 2 of relay 6, and contact 2 of sequence switch spring C. The other shunt circuit may be traced from contact 1 of sequence switch spring D, through right-hand armature 3 of relay 5, and left-hand armature 1 ofrelay 6, to the circuit, which takes place in position 1 at sequence switch springs C and D, will be bridged over by these shunt circuits, and the subscribersreceiver will not become noisy during any portion of the wi e out period. It will now be assumed that the callin subscriber is a party line subscriber, an that connection is desired with another party onthe' same line. In a reverting call of this 7 7 nature, when the operator, in response to the request of the subscriber, has stepped the connector switch wipers to the terminals of the line desired, the circuit will again .be completed through relay 16, but, as exlained in the description of a call for a usy line, relay 16 will not receive enough current to cause its energization. In this case, however, a circuit will be completed which will shunt out relay 24. This circuit can be traced from the sleeve of the jack, to the test terminal at the connector switch, the test wiper of the connector switch, contacts 1 and '4 of sequence switch sprili? L, contact 1 of sequence switch spring contacts 2 and 4- of sequence switch spring Q and resistance coil 25, to battery. Switching relay ground. Thus, the break in 24fwil1 therefore be deenergized and a circuit willbe completed from battery, through the interrupter 45, relay 22, sequence switch the'break period is of insufiicient duration to cause itsdeiihergizatibn, The attraction of the left-hand armature of relay 22 will close a circuit from-theground on the arma ture tovcontact. 2 of sequence switch spring E, and thence throughtthe operating magnet of the sequence-switch, .to battery. This 'will move the sequence switch into its eighth position. 7 When the operator ascertains that it'is a reverting call, she will request the calling subscriber to hang up his're'ceiver. When the calling subscriber hangs up'his receiver, the answering supervisory lamp 8 will be lighted, and the operator, upon seeing this signal, will actuate the proper ringing key so as to project out on the line ringing current of the required character for calling the particular party line subscriber -the high resistance winding of relay 16.

This wilhin effect, shunt out the high resistance winding of relay 16, and this relay will be operated, due to the increased flow of current, the cause of which was pointed out in the description of a connection with a busy subscriber. These circuit conditions are shown theoretically in Fig. 4, in which the dotted lines show the electrical connections for forcing the operation of the test relay 16. The operation of relay 16 will move the sequence switch into its 9th position, but due to the energization of relay 22, a-circuit will be completed in this position of the sequence switch from the ground on the left-hand armature of relay 22, through contact 2' of sequence switch spring E, and the operating magnet of the sequence switch, to battery. The sequence switch will consequently move into its 10th position. When the sequence switch leaves the 9th position, the answering end of the cord circuit will be 0 ed at contact 1 of sequence switch D, an contacts 1 and 2 of sequence switch spring C. Consequently, when the operator rings out on the line in the 10th position of the sequence switch, the ringing current will not be shunted back through the answering end of the cord circuit. When the answering end of the cord circuit is thus opened, the two subscribers on the party line are connected in multiple to the calling -end of the connecting circuit, and the battery for conversation purposes is fed to these two subscribers over a circuit which may be traced from ground, through winding 16 ,of the repeating coil, the tip contacts of the ringing key, contacts 1 and 2 of sequence switch spring P, contact 4 of sequence switch spring J, to the tip side of the line, and back over the ring side of the line to contact 2 of sequence switch spring N, contacts 2 and 1' of sequence switch spring Q, the ring contacts of the ringing key, supervisory relay 23 and winding 17 of the repeating coil, to battery. When the answering end of the connecting circuit is opened, answering supervisory relay 9 will be deenergized, and consequently the answering supervisory lamp 8 will light. 1 The calling supervisory lamp will also be lighted. These two lamps should now be placed under the control of the. calling supervisory relay 23, and this is accomplishedby means of relay 49. When the sequence switch moves into its 10th position, a circuit is completed from battery, through the left-hand winding of relay 49, contacts 3 and 4 of sequence switch spring C, resistance coils 28 and 21, contact 2 of sequence switch D, to ground. This will operate relay 45. When either the called subscriber answers or the calling subscriber again removes his receiver, the subscribers loop will again be closed causing the energization of calling supervisory relay 23. The attraction of the armature of relay 23 will shunt out the calling supervisory lamp 20. A shunt will also be established for the answering supervisory lamp 8, which may be traced from battery, through the armature and make contact of relay 23, the armature of relay 49, right-hand coil of relay 49 and resistance coil 52. This will raise the potential of the left-hand side of the answering supervisory lamp, which will decrease the How of current sufficiently to extinguish the lamp. When the subscribers have completed the conversation and they both hang up their receivers, relay 23 will be denergized and the shunt circuits about supervisory lamps 8 and 20 will be removed, and these lamps will be-relighted. This will indicate to the operator that conversation has been completed and she will withdraw the answering plug from the calling line jack, which will restore the switching apparatus to normal, as previously described.

The specific embodiment of my invention herein described may be considerably changed or varied without departing from the spirit of my invention, and hence I do not herein-specifically limit myself to the exact detail construction and arrangement of apparatus. The invention may obviously be applied to many other types of telephone systems.

What is claimed is:

1. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of aconnecting circuit adapted to be united. therewith,means to placea busy potential -on all of the multiple test 'contacts of the telephone line whenever ,a connection is made therewith and to continuously maintain this condition to prevent automatic connection with other lines until the line is released, and means under the control of the operator toautomatically connect with said busy contacts irrespective of the existing busy condition when connection with a party on the same line is desired by the calling subscriber.-

2. In a telephone exchangesystem, the combination. .v with telephone lines having multiple terminals, of connecting circuits of a single type common to all of said lines adapted to be connected with and interconnect saidlines, means to render telephone lines bu'sy whenever a connection'is made therewith and to'continuously maintain this condition to prevent automatic connection therewith until the lines are released, and means underthe control of an operator" to .0 automatically connect. with any busy line irrespective of the existing busy condition.

3. In a telephone exchange system, the combination with a-party telephone line having multiple terminals, of a connecting 105 circuit adapted to be united therewith having ananswering and a calling end, means under the control of an operator to automatically interrupt theanswerinlg end of 7 said connecting circuit, and means to auto.- matically connect two subscribers of the party line overthe calling end of said connecting circuit. a

4. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, means to place a busy test condition upon said terminals when the telephone line is connected to said connecting circuit, means under the control of an operator to automatically connect the calling end of said connecting circuit to the subscribers lineirrespective of the existing busy test, and means to automaticallyinterrupt the answering end of said connectin circuit.

5. In a semi-automatic telephone system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, multiple test terminals rendered busy whenever a connection is established with said line, a signal device associated with the connecting circuit to indicatewhen the connecting circuit isincontact at both ends with multiple terminals of the same line, automatic means under the control of the operator to disconne'ct the answering end of the connecting circuit and to connect the party line subscribers over the calling end 0 cuit. v

6. In an automatic telephone system, the combination with a party line having mul-' tiple terminals, a testc'onductor extending to contacts at each of said multiple, terminals, means for maintaining abusy potential on said test conductor whenever a connection is made with said line to prevent connection with'said line by other subscribers when saidline is busy, an indicator, autothe connecting cirmatic means to control said indicator in one adapted for connection with the same line when the "line is called, a' test conductor extending to contacts at each of said multiple terminals, means for maintaining a busy test on said conductor whenever a connection is made with said line'by either of said devices, means to' revent an automatic connection with said lme when it is busy, means to indicate a busy line, means to-indicate a revertive call, automatic means controlled by an operator to connect with a busy line without removing the busy potential from said line, and means controlled by the operator to connect with a busy line on a reverting call without removing the busy potential from said line.

8. In a telephone exchange system, the combination with a party line having null jtiple connections, of e connecting circuit adapted to be united therewith, means to ren er the telephone line busy when taken for use to prevent connection therewith by other lines, and automatic means under the control of thee rater for completin a revertin connection notwithstanding t e continue application of said busycondition.

e. in a telephone exchange system, the combination with a arty line having multiple connections, o a connecting. circuit adapted to ho united therewith, automatic means for connecting a party line subscriber to both ends of the connecting circuit, means including an indicator to' indicate such a connection, and means controlled by an operator to interrupt the answering end of the controlling circuit when such a connection has been indicated .and to. complete the connection by means of the calling end of the connecting circuit.

10; In a telephone system, a plurality of subscribers lines, cord circuits for interconnectmg them, automatic means in the cord circuit for testing a subscribers line, a relay inssaid cord circuit, an indicator associated with the callin end of said cord circuit, said relay controlling the indicator whereby characteristic signals are given for either a busy line or a reverting busy line.

' 11. In a telephone system, the combination with party line subscribers, of manual means for connecting with a calling subscriber, automatic means for connecting with a called subscriber, means to render a calling or called line busy to prevent other subscribers from connecting therewith, means including a signal to indicate that the called line is idle, means including the same signal to indicate that the line is busy, means vincluding the same signal to indicate a retest relay, the operation of the first test relay shunting out one winding and thus raising the potential of the said test terminal to prevent the operation of said second test relay connected to the terminal, and means controlled by the operator 'to shunt out one winding ofsaid second relay and effect its operation.

13. In a tele hone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be unitedtherewith, an answering and a calling end for said connecting circuit, a ringing key, means operated by said key on a reverting connection to automatically interrupt the answering conductors of said connecting circuit without severing the connection at the answering line terminals, and means to automatically connect two subscribers of a party line over the calling end of said connecting circuit.

14. In a telephone exchange system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, means to render the telephone line busy whenever a connection is made therewith and to continuously maintain this condition to prevent automatic connection with said line until it is released, a ringing key, means actuated by said key when operated to automatically connect with said line irrespective of the existing busy condition when connection with a party on the same line is desired by the calling subscriber.

15. In a telephone exchange system, the combination with telephone lines having multiple terminals, of connecting circuits of a single type common to all of said lines adapted to be connected with and interconnect said lines, means to render a telephone line busy whenever a connection is made therewith and to continuously maintain this condition to prevent automatic connection with said line until the latter is released, a key, means actuated by said key when operated to automatically connect with a busy line irrespective of the existing busy condition.

16. In a telephone system, the combination with telephone lines having multiple terminals, of a connecting circuit adapted to be connected with said lines, means to render a line busy whenever a connection is made therewith, a switching relay, means to operate said relay whenever a connecting circuit is taken for use, a signal controlled thereby to indicate a connection to the terminals of a busy line, means to shunt and deenergize said relay when connected to line terminals on a reverting call, thereby controlling said signal to indicate a reverting call.

17. in an automatic telephone system, the combination with telephone lines having multiple terminals, connector switches of a single type common to all of said lines, oi means including one of said connector switches for interconnecting said lines, means to render a line busy whenever a connection is made therewith to prevent automatic connection therewith until the line is released, and means to cause said con nector switch to automatically connect with a busy line irrespective of the existing busy condition.

18. in a telephone system, the combination with a party telephone line having multiple terminals, of a connecting circuit adapted to be united therewith, a connector switch as sociated withsaid connecting circuit, means to render a telephone line busy whenever a connectionis established therewith, means to advance the connector switch wipers to the terminals of the line in establishing a connection regardless of its busy or idle condition, a sequence switch, means to operate the sequence switch to close the connecting circuit when saidwipers connect with an idle line, means to render the sequence switch inactive when said wipers connect with a busy line, and means controlled by an operator to operate the sequence switch to close the connecting circuit to connect two subscribers of a party line regardless of the busy condition of the called line terminals.

19. In a telephone system, the combination with a subscribers line having multiple terminals, of a connecting circuit, a con nector switch associated therewith, means to connect the wipers of said switch with the terminals of a busy or idle called line, a sequence switch, a relay whih operates whenever a connection is estab ished with an idle line thereby operating said sequence switch to close a connecting circuit, means to prevent the operation of said relay when connected to a busy line and thereby prevent the operation of the sequence switch, and a key operable to energize the relay, when said wipers are connected to a busy line, thereby operating the sequence switch and closing the connecting circuit.

20. In a telephone system, the combination with a party telephone line, of a connecting circuit, a connectorswitch associated there with, means to render a line busy whenever a connection is established therewith, means to connect the wipers of said connector switch with the calling terminal of a calling subscribers party line, means including a signal to indicate a reverting call, a relay which operates whenever said wipers connect with an idle line and which does not operate when said wipers are connected to a busy line, a sequence switch, a ringing

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