BE411026A - - Google Patents

Description

       

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  Improvements to telephone systems or similar systems.

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   The present invention relates to telephone systems and relates more particularly to systems in which connections are made by means of automatic switches,
In general, the object of the invention is to provide an improved control apparatus for establishing a connection in which the operating speed of the switches must not be kept within determined limits because the apparatus used for the establishment of the connection will always wait until the desired position of the switch is reached,
According to one of the characteristics of the invention, the switches have access to groups of lines and each switch must perform an automatic movement which makes it pass over each group until the desired group is reached,

   when the automatic movement in a group is completed a signal is transmitted to the common apparatus which controls the establishment of the connection and the beginning of the automatic movement in each subsequent group is triggered under the control of the common apparatus by the action identical signals to determine when the desired group is reached.



   In a group selector when the desired group is reached a signal is transmitted from the common switchgear to the switch to prevent any subsequent automatic movement in groups and to cause a search movement for a free line in the group, while that in a connector the signal causes a forward movement on the individual lines of the group under the control of the common equipment.



   In one of the most interesting embodiments of the invention, the signals transmitted to the common equipment

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 consist of a change in the resistance of the circuit connecting the common equipment to the switch while the signals transmitted to the switch are given by the transfer of a negative polarity from one wire of the circuit to another wire of the same circuit.



   According to another feature of the invention in a switch which performs step-by-step movement on the individual lines to which it has access signals consisting of variation of resistance of the circuit are counted by the common apparatus to determine the extent of the step movement. stepping while when the desired line is reached a signal is transmitted from the common equipment to the switch to stop the stepping movement and to establish the connection to the desired line.



   The features and operation of the invention will be described in detail in the following specification with reference to the accompanying drawings comprising Figs, 1 to 10 inclusive. Fig. 1 gives a diagram in single lines showing the junction system of two groups of 500 lines. Fig. gives the mode of juxtaposition of figs. 2 to 10, inclusive. Figs. 2 to 10 inclusive, show by the usual means the selector, the connector, the improved combined call controller as well as the associated apparatuses which are necessary for the understanding of the invention.



   Referring now to the upper part of fig. 1 it can be seen that the subscriber lines are divided into groups of 5 hundreds and that these groups are in turn divided into groups of 100 lines. The rectangles marked 100 in the upper left part each represent the circuits of 100 lines which are connected to the banks of the primary line seekers,

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 assuming that there are 10 primary line seekers for each group of 100 line circuits.



   Researchers end up with primary junctions which are multiplied on the benches of secondary researchers and in the benches of researchers of groups associated with call controllers. The secondary investigators result in secondary groups of trunk relays and primary group selectors. There are as many secondary investigators and secondary groups of trunk relays as necessary to account for the conditions of the traffic transmitted by. the group of 500 lines. The banks of the primary group selectors are connected to secondary group selectors and are multiplied as shown in the figure. The secondary group selectors have access to connectors and the connectors in turn have access to subscriber line circuits in the usual manner.

   Each group of 100 subscribers has a starter wire leading to a starter relay associated with the distributor. The distributor has access to as many combined call controllers as necessary to account for the traffic in this subgroup.



  As previously said the group finder of each call controller is connected to the primary trunks while a secondary trunk finder associated with each call controller is used to do so. selection of a secondary group of junction relays.



  The combined call controller includes a number of relays and switches which will be described more fully when examining the other figures. The lower part of fig. 1 shows the second or last group of 500 lines, it is identical to the upper part, it is given to show the normal links between the primary and secondary switches.



   In fig. 2 the circle on the far left re-

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 shows the station of subscriber A whose number is 1121. Line wires 1 and 2 go from the station to the line circuit including relays 10 and 20. Wires 1, 2 and 3 are the connector wires, they end via the cable 4 to the connector bench shown in fig. 5. The wires 6 and 7 are the starting wires intended to mark the calling group and to trigger the operation of the devices. The calling end of the line circuit terminates at the primary finder banks.

   Mechanically, the mechanism of the primary seeker is identical to the mechanism of the well-known rotary switch except that it was provided with two groups of single brushes, connected in multiples, mounted on the same axis, the brushes 101, 103, 105 and 107 constituting a group and the brushes 102, 104, 106 and 108 constituting the other group.



  A separate group of benches is provided for each group of brushes, the two groups of benches being placed side by side. The two groups of brushes are wedged at 180 on the axis so that when a group of brushes leaves the last group of contacts on its bank, the other group of brushes engages on the first group of contacts on its bank. . As each bank represented has a capacity of 50 lines, the primary researcher therefore has access to 100 subscriber lines. In the present case, the primary researcher only includes the brushes, the benches and the appliances for the control of his movement.



   Primary searchers are connected to primary junctions that lead to secondary searcher banks and group searcher banks associated with combined call controllers. The secondary researcher shown in fig. 2 comprises a 50 point switch which is mechanically and operationally identical to the well known rotary switch. Each

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 secondary researcher leads to a secondary group of junction relays shown in fig. 3.



   The secondary group of junction relays shown in fig. 3 includes conversation power relays for calling and called subscribers and connection blocking relays after release of the combined call controller. In the lower part of fig. 3 bn has been shown the secondary junction searcher brushes associated with the particular combined call controller shown in fig. 6, 7, 8 and 9. Each secondary group of junction relays is connected to a primary group selector such as the one shown in fig. 4. The primary group selector shown in fig. 4 includes a certain number of relays and an electronic control of the movement of the brushes on the contacts of the benches.

   The brushes and banks are mechanically arranged in a manner similar to that of the primary seeker brushes and banks and in this case the primary group selector brushes have access to one hundred secondary group selectors represented by the rectangle. In addition, the bench contacts are subdivided into groups of 10 contacts each numbered as shown schematically for the contacts accessible to brushes 341 and 342. The primary selector brushes are always returned to the normal position for which the shaft springs 515 and 316 are open as shown in the figure.

   One of the junctions accessible in the 4th group of bank contacts of the primary selector and in the fourth group of bank contacts of the other primary selectors similar to the first is shown in the plan, it includes the wires 352, 356, 358 which lead to the selector switch. secondary group represented by a rectangle in fig. 4. The secondary group selector is identical in circuit point of view and in point

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 mechanical construction view to the primary selector shown. The banks of this secondary selector as well as the banks of similar secondary selectors are connected to a number of groups of connectors in the well known manner.



   The connector shown in fig. 5 is accessible to the fifth junction group of secondary selectors.



  The connectors, from a mechanical point of view, are identical to the group selectors, each of them includes 6 relays and an electro controlling the movement of the brushes. The brushes of the connector have access to one hundred lines, they are returned to the normal position when the connection is released.



  The connector banks are likewise divided into groups of 10 lines and the lines end in the connector banks of these groups in the manner indicated by the numbering applied to the banks accessible to brushes 471 and 472. To the right of the connector in fig. . 5 shows the line circuit, the banks of the primary researcher and the station of subscriber B.



   A number of two-stroke relays are represented in the selector and the connector, these relays by attracting at the first beat close only the armatures marked I in Roman figures, while at the second time they close the armatures marked II in figures Romans.



   At the extreme left of fig. 6 shows the distributor and the associated starting relays 31 and 41 for two of the groups of 100 lines, it being understood that a relay such as 31 or 41 is provided for each group of 100 lines. The starter wires 6 and 6 'each come from a group of 100 lines and terminate at the brush 33 of the distributor. The distributor has access to as many combined call controllers as necessary to take into account the traffic sent by this group of 500 lines. The part

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 top of fig. 6 shows the group finder brushes associated with the particular combined call controller shown in fig. 7, 8 and 9. As shown, group finder brushes have access to primary junctions such as the one shown in fig. 2.

   Marker wires 7 and 7 'pass through start relays, such as relays 31 and 41, and are connected to multiple bank contacts accessible to group finder brushes 611 to mark the calling group. The mechanical construction and operation of the group finder is identical to the mechanical construction and operation of the well-known rotary switch. The group finder and the secondary junction finder are part of the combined call controller shown in fig.



  7, 8 and 9.



   In fig. 7 shows a number of relays of one of the combined call controllers. The relay 740 of fig. 7 has a weighted armature 741 by means of a weight 742 at its right end which vibrates between contacts 743 and 744 when the armature is released. The relays shown in fig. 8 are also part of the combined call controller. At the extreme right of fig. 8 is shown the OS counting switch which from a mechanical point of view is identical to the 11-point rotary switch in which the brushes are returned to the normal position and in which the brushes advance step by step with each attraction of the electro 885.

   In fig. 9 we have shown the emission control switch S comprising the brushes 913 to 915, included, the electro 91o which advances the brushes step by step at each release and the shaft springs 912 which control the re-installation of the brooms after the show. The emission control switch S is mechanically identical,

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 to the CD count switch. The SS sequence switch and the 4 recording switches RA, RB, RC and RD are mechanically identical to the well-known rotary switch, but in this case the switch brushes are set in motion and advance one step further. not when the control electro is pulled in.

   Each of these latter switches has shaft springs controlling the repositioning of the brushes after emission.



   Fig. 10 shows a busy relay 500 placed in a remote office and two jumper wires 505 and 507 terminating at the local office where the line wires arrive at an RC translator coil and an incoming repeater comprising several relays. Relays 510 and 520 are polarized relays which pull only when current is flowing through the windings in a suitable direction. Incoming repeaters lead to secondary group selectors which have access to connectors as shown in fig. 4.



   General operation.



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For the purposes of description it was assumed that the subscriber lines were arranged in groups of 500 lines, that each group of 100 lines was served by 10 primary searchers, and that these primary searchers were concentrated through the secondary searchers in a group. of 50 secondary junctions. Each primary junction includes a primary searcher for the calling line search and this junction leads to the secondary searcher banks for establishing the final connection. Each primary jonctipn is also multiplied at the benches of group researchers in order to associate a combined call controller with the

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 calling line.

   Each secondary junction consists of a 50-point secondary line finder for searching for primary junctions, each secondary junction is also associated with secondary junction relays for blocking the connection, for metering control and for power supply. subscribers calling and called. These groups of secondary junction relays result in primary group selectors.



   When a subscriber makes a call the line relay of his line circuit draws in the usual manner to trigger the operation of a free call controller through the distributor and to mark the calling group in the group finder bank of the subscriber. selected controller and to mark the calling line in the banks of the primary researchers. The group finder associated with the entered controller will first search for a free primary trunk in the particular subgroup of 100 lines from which a call originated. As soon as this operation is completed, the primary searcher associated with the selected primary junction will search for the calling line. As soon as the calling line is found the subscriber's cut-off relay pulls in and the connection is established through the controller.



   As shown in the preceding description, it is clear that for each call sent two selection movements are necessary to find the calling line.



  Because the call controllers can only serve a maximum of 5 sub-groups of 100 lines, it is possible that the sending of the invitation to be transmitted is delayed when calls are sent simultaneously in different sub-groups. . This is avoided by the following provision, if, for example, calls are

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 sent in 3 sub-groups at practically the same time, the first controller entered will find, through its group finder, the sub-group in which the call was made, at that time and before the calling line has A second call controller will be found as a result of advancement of the distributor to serve the second call, etc.

   In other words, each subsequent call, if it is from a different subgroup, does not require waiting for the complete selection of the calling line but only sufficient time to allow the call controller selected to find a free junction in the subgroup from which the call originates.



   As soon as the caller is connected to the controller, the invitation to transmit tone is given online indicating that transmission of the desired number can begin.



  The pulses are then stored in the call controller by the registration switches RA to RD inclusive. As soon as the call controller has been put into service, its associated secondary junction finder searches for a secondary junction. free. As soon as the junction is found, it is kept available by the call controller to receive the transmission of a call as soon as the impulses sent by the subscriber have been collected by the recording switches:

   Immediately after the seizure of the primary junction by the group finder and the seizure of the secondary junction by the junction finder, a local circuit is established, its function is to advance the secondary finder associated with the seized secondary junction to 'at the primary junction on which the call was made by the calling subscriber. The connection between the primary junction and the secondary junction is

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 does independently of all the other operations which are carried out at the same time and does not require for its establishment any relay or any apparatus other than that of the call controller. After that the secondary finder has been connected to the primary junction. desired the circuit between this one and the secondary junction remains open.



   Instead of sending control pulses to the selectors and connectors to bring the brushes in front of the desired group, taking a selector or connector causes it to automatically advance to the start of the first junction group in the case of a. group selector or up to the first group of "ten" in the case of a connector. At this moment a signal is sent by the call controller following a variation in the value of the current. This variation causes a release and a re-pull of the line relay in the selector and the same operation is repeated until the brushes are at the start of the desired group, the desired group being determined by the position of the controller's register switches.

   By this operating mode, the forward speed of the switch must not be kept between certain particular limits because the controller will always wait until the suitable position is reached. Assuming that the called line can be seized the connector will send an appropriate signal to the controller as soon as the connection has been established. At this point, the call controller, associated group finder, and trunking finder release and a talk circuit is established between the subscriber lines through the primary line finder, finder of secondary lines, disassembly of secondary junction relays, the

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 group selector associated with it, the secondary selector and the selected connector.



   In the event that one of the selectors encounters a busy trunk or in the event that the called line is busy, the entire connection, including the primary selector and the secondary selector, will be instantly released and made available for other calls; the busy tone will be transmitted from the call controller to the calling line.



   After having given a general description of the operation of the system, we will now move on to a detailed description. For this purpose, it will be assumed that subscriber A wishes to make a call; unhooking his receiver, he closes the circuit of his line relay 10 as follows: positive, armature 23, wire 2, loop of the subscriber's set, wire 1, armature 21, winding of line relay 10, negative. At armature 11, relay 10 disconnects the winding of cut-off relay 20 from wire 3 coming from the connector and connects the negative through the winding of relay 20 through wire 5 to the contacts of the line finder bench primary to mark the calling line.

   At armature 12 relay 10 connects positive to wire 6 to close the vibrating relay 740 circuit of the controller as follows: positive, armature 12, wire 6, armature 32, brush 33 of the distributor which has preselected the call controller free, wire 628, armature 715, top winding of relay 740, negative. At armature 13, relay 10 marks the calling group in the banks of group seekers associated with call controllers by marking as many multiple bank contacts accessible to the brooms - such as the broom 611 - as there are seekers primary in the group of one hundred calling lines. This marking

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 Calling Group allows group finders to locate the particular group of one hundred lines that is calling.

   Relay 740 attracts its weighted armature 741 to close contacts 743 thereby establishing the pull circuit of slow release relay 750 through armature 762. Relay 750 pulling to l armature 751 connects the secondary junction finder test brush 275 to the upper winding of the secondary junction finder test relay; at armature 752 it closes its own control circuit through armature 733 and wire 288 to electro 290 of the secondary junction finder through switch contact 289; at armature 753 it prepares at one point the circuit for connecting the invitation to be transmitted to the calling line, at armature 754 it prepares the blocking circuit of relay 770;

   at armature 755 it completes its own blocking circuit independent of armature 762; at armature 756 it closes the attraction circuit of the slow relay at attraction 720; and at armature 757 it prepares the advance circuit of the emission control switch S. The electro 290 of the secondary junction finder draws in the circuit described above and to its switch springs 289 it interrupts its own circuit which makes it relax, so it causes its brushes to advance by one step at each release.

   The electro 290 interrupts its circuit like a vibrator to cause the brushes of the secondary junction finder to advance step by step until the test brush 275 engages on a free junction characterized by the presence of a negative on the bench contact encountered by the brush 275. When the test brush 275 encounters a free junction, the test relay 770 attracts following

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 the circuit: positive through the top winding of the test relay 770, armature 751, wire 285, test brush 275, control wire 256, top winding of relays 320 and 330 of the primary group selector, negative.



  The test relay 770 alone draws along this circuit, at the armature 771 it prepares a grounding circuit for the negative wire 252 or the positive wire 268, depending on the state of the relay 810. At the armature 772 the relay 770 prepares a circuit for connecting the negative through the winding of relay 830 to negative wire 252 or positive wire 258, depending on the state of relay 810.

   At armature 773, relay 770 immediately opens the circuit of electro 290 to stop the brushes of the secondary junction seekers on the selected free junction; at armature 774 it prepares at one point the circuit of release relay 210 in the group of secondary junction relays; to the armature 775 it connects the capacitor of the spark arrester and the resistor 779 to the electro 161 of the secondary line finder; at armature 776 he prepares the attraction circuit of the alternating current relay 790; at armature 777 it prepares the circuit of relay 780 which is short-circuited by the positive taken at armature 791;

   and at armature 778 it bypasses the top winding of test relay 770 to connect a direct positive to wire 256 through armature 751, wire 285 and brush 275 to cause the relay to attract two-stroke 320 of the primary group selector at the first stroke to operate armature 324 only. Relay 350 being a marginal relay will not attract with its top winding in parallel with the top winding of relay 320. Relay 320 only pulls its armature 324 to open the primary group selector pickup circuit.



   The slow relay at attraction 720 attracts next

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 the circuit: positive, transmission control switch brush 913 engaged on its first bank contact or normal position contact, wire 792, armature 756, winding of relay 720, negative.

   At the armature 721, the relay 720 closes the own control circuit of the electro 618 of the group finder by means of the armature 711 and the wire 620; at armature 722 it closes the blocking circuit through the lower winding of the test relay 770 and completes the blocking circuits of relays 700 and 710 through their upper windings, but these two relays being marginal relays do not attract in this moment by their upper winding; at armature 723 it prepares at one point the circuit of the group finder test relay and at armature 724 it closes the circuit bypassing the lower winding of the group seeker test relay 710 when the searcher test brush of group 614 encounters a busy primary junction.

   When brush 614 encounters a grounded bank contact indicating that the corresponding primary junction is occupied the lower winding shunt circuit of the group seeker test relay 710 is established as follows: positive, bank contact on which the brush 614 is engaged, wire 624, armature 712 and contact at rest, armatures 724 and 723, lower winding of the group finder test relay 710, contact at rest and armature 705, positive.

   When the group finder's 611 test brush meets one of the multiple bank contacts to which the calling group negative is connected at the same time as the 614 primary test brush does not encounter a grounded bank contact the circuit attraction of the researcher test relay

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 group 710 closes as follows: positive through armature 705 and closed contact, lower winding of group seeker test relay 710, armature 723, wire 627, group 611 test brush, one of the multiple bank contacts through the winding of relay 31, common starting wire 7 for this group of 100 lines, armature 13, resistance, negative.

   Relay 31 draws in series with group test relay 710 and armature 32 disconnects the start positive from brush 33 in the event that no other call is pending. The group test relay 710 by drawing in series with the relay 31 when the calling group is found, to the armature 711 opens the circuit of the electro 618 to stop the brushes of the group finder on the bank contacts which lead to a free primary junction; at armature 712 and at rest contact it opens the shunt circuit of the lower winding of relay 710 and at its working contact it prepares the test circuit of the line test relay 700 which will attract when the primary searcher is selected will reach the calling line.

   At armature 713, relay 710 puts wire 625 to earth through armature 706 to close the attraction circuit of electro 118 of the selected primary seeker; at armature 714 it closes a common spark arrester circuit for the electro of the primary line finder, at armature 715 it opens the circuit of the upper winding of relay 740 and at armature 716 it puts the wire 629 to earth to attract the electro 36 of the distributor to cause the distributor brushes to start and to search for a free combined call controller which will be used for the next call.



  The distributor electro 35 attraction circuit includes: ground wire 629, bank contacts

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 on which the brush 34 is engaged, the switch springs 36, the winding of the electro 35, the negative.



  Electro 35 works like a vibrator as long as brush 34 remains engaged on grounded bank contacts to advance the distributor brushes to a free calling controller. The circuit of attraction of the electro 118 of the primary researcher is as follows: at armature 713, armature 706, wire 625, brush 613, wire 621, switch springs 119, winding of electro 118, negative. Electro 118 works like a vibrator interrupting its own circuit at switch springs 119 until line test relay 700 pulls in and opens the above circuit to armature 706.

   During the step-by-step movement of the electro 118 the common spark arrester circuit closes through the wires 120 and 626 to the capacitor 716, the resistor 717 and the earth to the armature 714.



   Relay 740 releases when its circuit is open to armature 715 or as a result of operation of the distributor, and on releasing it releases its armature 741 thereby causing vibration of the weighted armature between springs 743 and 744 for a time determined. Each time the armature 741 comes into contact with the springs 743 or 744 the slow-to-release relay circuit 750 closes again to keep this relay engaged. The ballast 742 of the spring 741 can be adjusted so that this spring vibrates for a number of seconds before it returns to rest between the springs 743 and 744. In this case it is assumed that the weighted armature 741 will vibrate for a period of time. period of approximately 4 seconds and that it will therefore keep relay 750 engaged during this period.

   Relay

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 750 in normal system operation, however, will not release unless a fault occurs or the caller does not transmit for the required period. Busy subscriber test leads are grounded and therefore when primary finder test brush 105 or 106 encounters a grounded bank contact and a busy line terminates a circuit closes as follows: wire 115, 614 brush, 624 wire, 712 armature and NO contact, lower winding of line test relay, positive to shorted relay 700.



  The 700 line test relay being shorted will not draw in this circuit. When a calling line is found the test brush 105 or 106 will encounter a negative passing through the winding of the cutoff relay 20 and the armature in parallel to cause the pull of the test relay 700 following the circuit described above. .

   Line test relay 700 drawing to armature 701 connects positive to wire 281 to close the electro 161 clean control circuit of the secondary seeker; at armature 702 it closes the circuit of the secondary winding of transformer T in series with alternating current relay 790; armatures 703 and 704 it closes the circuit containing the subscriber's line to attract the line relay 730; at armature 715 it puts wires 624 and 115 to the ground to attract the cut-off relay 20, and to mark the primary junction for occupancy, at armature 706 it opens the circuit of electro 118 for stop the primary searcher brushes on the bench contacts where the calling line wires end.

   The cut-off relay 20 by attracting to the armatures 21 and 23 disconnects the line relay 10 and the positive of the line wires 1 and 2, at the armature 22 it disconnects the negative

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 with its contact at rest and its contact at work it closes its blocking circuit to wire 5 earthed by wire 115. Line relay 10 releases and armature 11 occupies the called party's test wire. 3 by connecting the positive to it through the grounded wire 115, the brush 105, the wire 5, the on contact and the armature 22, the armature 11 and the off contact, the wire 3. At armature 12 relay 10 removes the positive of wire 6 to remove the starting positive and at armature 13 it disconnects the group marking negative of wire 7 and relay 31.

   Relay 31 circuit has been opened at armature 705 as a result of pulling relay 700. Additionally pulling relay 700 to armature 705 opens the original pull circuit of group test relay 710 , on contact with the work of the spring 705 it short-circuits the lower winding of the relay 700 but these two relays, 700 and 710 are now blocked by their upper windings and the positive to the armature 722.



   The line relay pull circuit 730 in the call controller is established as follows: positive, lower coil of relay 730, armature 704, wire 623, broom 615, wire 117, broom 107, wire 2, loop of calling subscriber A, wire 1, broom 101, wire 111, broom 616, wire 622, armature 703, top coil of line relay 730, negative. At armature 731, relay 730 closes the attraction circuit of the slow relay on release 760.



  To armature 761, relay 760 connects the invitation to be transmitted to the line of the calling subscriber as follows: current generator (fig. 9), shaft springs 933, wire 789, contact on and armature 755, armature 761, TC tone capacitor, armature 703, wire 622, broom 616, wire 111, broom 101, wire 1, caller loop.

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  At armature 762, relay 760 opens the original attraction circuit of relay 750, but this relay is kept attracted through its armature 755; at frame 763 it closes a shunt around frame 756 to keep release relay 720 attracted; to armature 764 it closes a circuit comprising the ground armature 815 and wire 793 as well as the lower winding of the relay 740 and the negative to make the relay 740 attract and keep the slow relay to release 750 in attracted position. At armature 765, relay 760 closes the draw circuit of relay 870 as follows: positive at armature 765, wire 794, coil of relay 870, negative.

   At armature 766 relay 760 closes the SS sequence switch electro 920 pull circuit as follows: positive to armature 766, wire 798, armature 901, electro coil 920, negative.



  Electro 920 attracts in the above circuit and engages brushes 923 on the first contact of the bank; it operates the switch spring 923. The SS switch shaft springs 922 close when the brush 923 engages the first contact of the bench.



   Relay 870, attracting, to armature 871 connects an alternating current source through the primary winding of transformer T through wires 787 and 788. At armature 872, relay 870 opens at one point on. CS count switch automatic return circuit; at armature 873 it prepares the circuit of relay 820; at armature 874 it prepares at one point the blocking circuit of relay 840; and to armatures 875 to 882, inclusive, it disconnects the earthed relay 880 of the emission control switch S, the sequence switch SS and the switches, recorders RA, RB, RC and RD so as to open the circuits

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 reminder of these switches.



   The circuit of attraction of the electro of the secondary researcher is as follows: positive to armature 791, contact at rest and armature 782, armature 777, armature 701, wire 281, brush 271, wire 160, switch spring 162 , winding of electro 161, negative. Electro 161 works as a vibrator to advance the secondary finder brushes step by step until brush 159 finds the wire marked by the group finder associated with the activated call controller.

   The wire marked by the group finder corresponds to the primary junction put into service, in this case it is wire 122 and therefore when the brush 159 engages on the contact of the bench where the wire ends. 122 AC relay 790 circuit closes as follows: AC relay right terminal 790, transformer secondary winding T, wire 283, brush 273, wire 160, brush 159, wire 122, finder brush 617 group, wire 621, armatures 702, 776 and 781, left terminal of ac relay 790. Since the circuit of the primary winding of transformer T was closed previously due to the operation of armature 871, the AC relay 790 draws following the circuit described above.

   At armature 791, relay 790 opens the control circuit of electro 161 and connects the secondary finder to the primary junction entered by the group finder, likewise, it removes the shunt to earth from the winding. of relay 780 which now draws through a negative taken through the winding of the high electro 161. As a result of the resistance / winding of relay 780 the electro 161 will not draw in series with this causes the brushes of the secondary researcher to stop on the selected primary junction, At armature 781, relay 780 opens the circuit of the relay to

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 alternating current 790 which now releases, at armature 782 it locks independently of armature 777 in the event that relay 770 releases.



   A brief summary will now be given of the operations which result from making a call, prior to the sending of the impulses by the caller. (1) The distributor has placed a call controller available in service. (2 ) The controller has placed its associated group finder on an available primary trunk to the calling hundreds group. (3) The controller at this time has moved the dispatcher forward so that another call controller can be activated if another call is pending. (4) The call controller ¯ has advanced the primary searcher associated with the selected primary junction to the calling line. (5) The associated secondary junction searcher the controller entered has selected a free secondary junction and a primary selector. (6)

   The call controller has brought the secondary seeker associated with the selected secondary junction relay group to a position where it can connect to the primary seeker already selected by the controller. Setting up the secondary searcher associated with the primary searcher does not establish any connection circuit. (7) The calling party's set is now connected to the controller and the controller is connected to the primary selector. The equipment between the primary selector and the primary searcher, i.e. the secondary searcher and the group of secondary junction relays, permanently associated with the secondary junction are kept ready to establish the connection, but are not put into operation. circuit so far and do not perform any function in establishing the connection.



   The calling subscriber can now send the

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 digits corresponding to the called party's number, in this case we assume that the calling subscriber transmits digits 4 - 5 - 6 - 7. following the transmission of digit 4, line relay 730 releases 4 times and at each time transmits an earth pulse through armature 732 in the following circuit: winding of relay 900, brush 923, engaged on its first bank contact, winding of electro 930 of the commu- recorder recording the first digit RA, negative.

   The recording switch RA being of the type with direct attack causes its brushes 934 to advance by one step under the action of each attraction of the electro 930 and since 4 earth pulses are transmitted via the armatures 766 and 732 , the brush 934 will come to engage on its fourth bank contact which ends with the wire N 4 contained in the cable 890. At the first step of the brush 934, the shaft springs 933 disconnect the invitation to transmit from the calling line and operate the springs. shaft 932 to prepare the return circuit of switch RA, which, however, is currently open at armature 877. Relay 900 draws in series with electro 930 and therefore maintains its release / sound delay. armature 901 operated for the duration of the pulses of each digit.

   At armature 901, relay 900 opens the circuit of the electro 920 which releases accordingly. At the end of the sending of the first digit, the slow release relay 900 releases and again closes the attraction circuit of the electro 920 to cause the advance of the brush 923 of the sequence switch. which engages on its second bank contact to prepare the second register switch RB for the transmission of the second digit.



   When the caller sends the second digit or digit 5 the line relay releases 5 times and as a result of these releases closes the next circuit; positive to

  <Desc / Clms Page number 25>

 armature 766, armature 732, wire 797, winding of slow release relay 900, brush 932 engaged on its second bank contact, winding of electro 940 of second register switch RB, negative.



   The electro 940 attracts 5 times and places the brush 944 on its fifth contact to which the wire ends? 5 of the cable 890. At the first step of the brush 944 the shaft springs 943 close the attraction circuit of the relay 820 to retransmit the first digit stored towards the primary group selector and to the shaft springs 942 it prepares the circuit of RB switch recall.

   The slow release relay 900 draws in the manner previously described to open the circuit of the electro 920; shortly after sending the second digit, the relay 900 releases to again close the circuit of the electro 920 which engages its brush 923 on the third bank contact to prepare the recording of the third digit. when the caller emits the third digit, i.e. 6, the line relay 730 releases 6 times and each time transmits an earth pulse through the relay 900 and the brush 923 towards the winding of the electro 950 and the negative . Electro 950 in an identical manner brings its brushes 954 to the sixth contact of the bench where conductor N 6 of cable 890 ends.

   At the first step of the brush 954 the shaft springs 952 close the return circuit of the RC recorder at one point. The shaft springs also close on the first step of brush 954 to prepare the circuit for relay 820 so that the call controller retransmits the second digit stored at the time the third digit is stored. The relay 900 and the electro 920 attract and release in the manner already described to bring the brush 923 to its fourth bank contact, after the emission of the third digit, to register the fourth digit.

  <Desc / Clms Page number 26>

 



   When the caller emits the fourth digit or digit 7 the line relay 730 releases seven times and on each release it transmits an earth pulse through the relay 900 and the electro 960 of the RD switch to the negative. The electro 960 moves its 964 broom forward by one step at each pull to bring the 964 broom to the seventh contact of the bench to which the N 7 wire of the 890 cable ends. At the first step of the 964 broom the shaft springs 962 close the RD switch auto-recall circuit at one point and also close the springs 963 to cause the controller to retransmit the stored third and fourth digits.



  After sending the fourth digit the relay 900 releases and the armature 901 again closes the attraction circuit of the electro 920 to bring the brush 923 to the fifth contact of the bench. The called number is now registered on the registrars RA, RB, RC and RD.



   As soon as the brush 944 advances one step at the moment of the emission of the second digit by the calling subscriber, the shaft springs 943 close the attraction circuit of the relay 820 to start the cycle of search operations of the group by the controller. Operation of shaft springs 943 closes the draw circuit of relay 820 as follows: positive to shaft springs 943, first bank contact on which brush 915 of the emission control switch is engaged. S, wire 853, armatures' 873 and 841, coil of relay 820, negative. The relay 820 by attracting, to the armature 821 closes the attraction circuit of the slow relay on release 850 as follows: positive to the armatures 813 and 821, first contact of the bank and brush 886 of the counting switch CS, winding of the relay 850, negative.

   At armature 822, relay 820 closes via a positive

  <Desc / Clms Page number 27>

 taken from the armature 813 the attraction circuit of the electro 885 of the counting switch CS, which by attracting puts its pawl in the attack position of the brushes 886 and 887 because the counting switch is of the type in to attack / direct.

   At armature 823 relay 820 prepares its blocking circuit and at armature 824 connects the negative through the winding of relay 830 to negative jumper wire 252 to draw line relay 310 into the wire. primary group selector as follows: positive to the normally open contact and to the 321 armature (fig. 4), lower high resistance winding of line relay 310, 323 armature, low resistance winding of line relay 310, closed contact and armature 321, wire 252, brush 277, wire 287, armature 811 and its idle contact, wire 784, armature 772, wire 785, armature 824, marginal relay winding 830, negative.



  Due to the high resistance of the lower winding of relay 310, relay 830 will not draw in the circuit described above.



   Relay 850 by attracting to armature 851 prepares the blocking circuit of the slow relay for release 860 and armature 852 closes the attracting circuit of the electro 910 of the emitted control switch. - Sion S via wire 854. The electro 910 by attracting puts its pawl in position to attack the brushes of the emission control switch and at the 911 switch springs it opens its control circuit at one point. reminder. The emission control switch S, as well as the counting switch CS as has been said previously, is of the type with indirect attack, the brushes being set in motion when the control electro is released.



   In the primary group selector shown in

  <Desc / Clms Page number 28>

   4 freezes the line relay 310 by attracting following the circuit described above, to the armature 312 closes the circuit for the automatic advancement of the selector brushes as follows: positive to the armature 312, switch contact 339 and contact at rest , armature 333, electro winding 338, negative. The electro 338 puts its pawl in position for the attack of the selector brushes and at its switch contacts 339 it interrupts the circuit described previously via the electro 338 to cause its release if the brushes 345 or 346 are engaged on a grounded contact.

   In this case since the brush 345 is normally engaged on a grounded group bank contact, the circuit closes by: positive in contact with the grounded bank, the brush 345, the armatures 313 and 333 and the winding of the electro 338 to keep it attracted. Line relay 310 high resistance lower winding short circuit closes as follows: positive to armature 312, switch springs 339 and its make contact, high resistance lower coil of relay 310, armature 321 and its contact at rest, positive. Since the high resistance winding of relay 310 is shorted the marginal relay 830 of the call controller draws in series with the low resistance winding of line relay 310.

   The operation which has just been performed, i.e. the modification of the resistance of the circuit leading to the relay 830 occurs each time their grounded group contact is encountered by the brushes 345 and 346. Since the contact of the grounded bank, accessible to brushes 345 and 346, designates the different junction groups, as mentioned previously, the modification of the resistance of the circuit towards the call controller takes place

  <Desc / Clms Page number 29>

 at the start of each junction group. The marginal relay 830 by drawing in series with the low resistance winding of the line relay 310, to the armature
831 closes the extraction circuit of relay 840, at frame 832 it prepares the blocking circuit of relay 810.



   The relay 840 by attracting the armature 841 opens the circuit of the relay 820 which consequently releases; at armature 842 it closes its own blocking circuit at armature 874 grounded. Relay 820 releases and armature 821 momentarily opens the relay circuit
850, at armature 822 it opens the circuit of the electro
885 of the counting switch CS to release the electro which causes the brushes of the counting switch 886 and 887 to advance on the second contacts of its bank. In this position the slow relay to release
850 remains attracted by means of the contacts multiplied to the ground on which the brush 886 of the counting switch CS is engaged in the second position and in the following positions.

   At armature 829, relay 820 opens the circuit of line relay 310 of the group selector and that of marginal relay 830 of the call controller, at armature 823 it closes the short-circuit of the coil of relay 840 to bring about his release. This short circuit is established as follows: left of relay 840, armature 825, armature 842, right terminal of relay 840.



   In the primary group selector releasing the line relay 310 at armature 312 opens the short circuit of the high resistance winding of line relay 310 and at armature 313 it opens the circuit maintaining the electro 338 attracted. The electro 338 therefore releases and advances the group selector brushes on the first contact of the first group bank.



   In the call controller the release of the relay
830 to armature 831 opens the circuit of relay 840. The

  <Desc / Clms Page number 30>

 relay 840 is slow to release since its winding is short-circuited to armature 825, and by completely releasing at armature 841 it again closes the attraction circuit of relay 820. Relay 820 attracts again and to the armature 822 closes the circuit of the electro 885 of the counting switch OS, to the armature 824 it again connects the negative to the winding of the marginal relay 830 through the low and high resistance windings of the line relay 310 to make it attract.



   Line relay 310 by drawing to armature 312 closes the automatic control circuit of electro 338 to advance the selector brushes automatically to the contacts of the first group. Closing armature 313 has no effect at this time because brush 345 does not encounter a grounded group bank contact until the last row of that group is reached. During the automatic operation of the electro 338 the "make" contacts of the switch spring 339 are closed for a sufficient time to practically short-circuit the high resistance winding of the line relay 310 and so that the relay 830 does not attract. during this operation.

   When releasing the electro 338, it continues to advance the selector brushes step by step until the brush 345 engages on a grounded group contact, in this case the last junction in the first group , at this time the electro 338 remains attracted by the group contact earthed by means of the brush 345 and the armatures 313 and 333 as described previously.

   At armature 312 and switch springs 339 and its on contact the low resistance lower winding of line relay 310 is set.

  <Desc / Clms Page number 31>

 short-circuited again to modify the resistance of the circuit leading to relay 830 in the call controller and again cause the pulling of relay 830 and to operate the call controller relays following the same cycle of operations as the one described above. That is to say that the relay 830 attracts and causes the relay 840 to attract as described previously. Relay 840 attracts and releases relay 820.

   Relay 820 causes the counting switch CS to advance one step and opens the circuit of relays 310 and 830. Releasing line relay 310 in the group selector advances the brushes of this selector to the first contact in the second group. Relays 830 and 840 release and relay 820 re-attracts as before.



  The relay 820 by re-attracting again closes the attraction circuit of the line relay 310 via the armature 820 to again cause the automatic advancement of the selector brushes on the last junction of the second group. From the above we can see that at this moment the brush of group 345 is engaged on a bank contact designating another group, the resistance of the circuit between the call controller and the selector is modified to cause the renewal of the cycle. operations which have just been described and to cause the advancement of one step of the counting switch CS in the call controller.



   Since the digit 4 has been registered in the RA register switch, 4 cycles of relay operations must take place and the CS count switch advances 4 steps, at this time the 887 brush meets the 4 grounded wire of the cable. 890, this earth extends through the brush 914 of the transmission control switch S, the brush 934 of the first recorder RA en-

  <Desc / Clms Page number 32>

 pledged on the fourth contact of the bench to which the wire ends? 4 of cable 890, through the fourth bank contact on which the brush 887 of the counting selector CS is engaged and through the winding of the slow release relay 860 to negative to attract this last relay.

   The relay 860 by drawing to the armature 861 closes the recall circuit of the counting switch CS; to the armature 862 it closes its blocking circuit specific to the armature 851 and to the armature 863 it closes the attraction circuit of the relay 810. The relay 810 by attracting to the armature 811 connects the positive of the armature 771 to negative wire 252 through wires 783 and 278; to the armature 812 it prepares the circuit for connecting the negative through the winding of the marginal relay 830 to the positive wire of line 258 through the intermediary of the wires 785, 784 and 286 when later the relay 820 is drawn, at armature 813 it disconnects the positive to prevent premature attraction of the electro 885 and relay 850; at armature 814 it prepares the blocking circuit of relay 820;

   at armature 815 it disconnects the positive of wire 793 to open the circuit passing through the lower winding of relay 740; at armature 816 it prepares its own blocking circuit and at armature 817 it opens at one point the return circuit of the emission control switch S.



   Relay 820 re-attracts when relay 840 releases, to armature 824 it connects a negative through the winding of relay 830 to wire 258 to cause the pull of relay 320 of the group selector at the second time to start the switching cycles. search for junctions of the first group selector. The attraction circuit of the group selector relay 320 in series with the call controller relay 830 is the

  <Desc / Clms Page number 33>

 following: positive via shaft springs 315, which close at the first step of the selector brushes, lower winding of the 2-stroke relay 320, normally closed springs controlled by the armature 334, wire 258, brush 276, 286 wire, 812 armature and NO contact, 784 wire, 772 armature, 785 wire, 824 armature, 830 relay winding, negative.

   The closing of the armatures 821 and 822 as a result of the attraction of the relay 820 has no effect at this time because the armature 813 is operated. At armature 823, relay 820 closes its blocking circuit specific to armature 814 earthed.



   The return circuit of the counting switch CS is as follows: with multiple contacts on which the brush 886 is engaged, armature 861, switch springs 884, winding of electro 885, negative.



  Electro 885 pulls and releases like a vibrator to advance the counting switch brushes until brush 886 no longer meets a grounded bank contact, currently brush 886 s 'will engage on its normal position contact.



  When the counting switch brush reaches the position shown on the plan, i.e. its normal position, the circuit passing through the winding of the slow relay on release 850 is open, it follows that this relay releases after a certain time. At armature 851, relay 850 opens the blocking circuit of relay 860 which releases after a certain time, at armature 852 it opens the circuit passing through the electro 910 of the emission control switch S. The electro 910 releases and advances the brushes 913 to 915 inclusive, by one step on their second bank contacts to control the retransmission of the second digit recorded in the second record.

  <Desc / Clms Page number 34>

 treur RB.

   The relay 860 being slow to release, releases after a certain time, at the armature 861 it opens at a point the return circuit of the counting switch CS described previously; at armature 862 it opens its own blocking circuit at one point, at armature 863 it opens the original circuit of attraction of relay 810, this last relay remains attracted by means of armature 816 and the armature 832 if relay 830 is still in the pulled position. The junction search cycle will normally be completed when the relay 860 releases, the indication will be given that the relay 830 is in the released position.

   At this time the send control switch S will be in the second position and relay 820 cannot re-attract until the third digit has been registered to the RC controller when the caller sends the third digit.



   Returning now to the primary group selector, a summary of its operation will be given below until the start of the junction search cycle. The attraction of line relay 310 closes the attraction circuit of electro 338 which works automatically until brush 345 or 346 engages on a grounded group contact indicating the start of a junction group. This grounded bank contact keeps the electro 338 attracted and bypasses the high resistance winding of relay 310, thereby starting a cycle of operations of the relays in the controller whereby the negative will momentarily be deleted from negative conversation thread 252.



  This removal of the negative of wire 252 causes the release of line relay 310 which in turn causes the release of electro 338, thereby advancing the selector brushes on the first group contact.

  <Desc / Clms Page number 35>

 



  After a short interval line relay 310 pulls back into the controller cycle of operations and reconnects the negative to the negative junction wire 252.



  This re-attracts line relay 310 which closes the circuit of electro 338 which automatically interrupts to advance the brushes step by step until brush 345 or 346 again encounters a group bank contact on. to ground indicating a next group of junctions. This cycle of group select operations continues until the called group is reached, at which point the controller connects negative to positive wire 258 to operate 2-step relay 320 at the second time.

   In this case, as the first digit emitted is 4, the selector brushes are operated for 4 cycles of group selection operations, the brushes remaining on the last junction of the third group, at this moment the negative is connected to the wire. 258 to attract relay 320 at the second time and start the junction search operation.



   Relay 320 on pulling at the second stroke, armature 322 connects the positive of armature 311 through the lower winding of junction test relay 330 to test brushes 343 and 344; at armature 323 it opens the circuit passing through the upper winding of line relay 310; at the armature 325 it closes the automatic control circuit of the electro 338 by means of the switching springs 339 and the armature 333; to armature 326 it connects group brushes 345 and 346 through armature 333 to the winding of electro 338. Electro 338 intermittently attracts and advances the selector brushes step by step looking for a free junction.

   As soon as

  <Desc / Clms Page number 36>

 the test brush 343 meets a free junction in this group, marked by the presence of a negative on the contact of the engaged test bench, the relay 330 attracts according to the circuit: positive to the armature 311, armature 322, lower winding test relay 330, test brush engaged on the bench contact where the free junction ends in this group, wire 356, upper winding of the 2-stroke relay and of the secondary selector test relay, corresponding to relays 320 and 330 of the primary group selector. Relay 330 to armature 331 connects the negative talk wire.



    252 via the brush 341 to the negative conversation wire 352 terminating at the secondary selector; at armature 332 it disconnects the upper winding of the 2-step relay 320 and connects the control wire 256 through the brush 343 to the control wire 256 thereby closing the attraction circuit of the 2-step relay of the secondary group selector which attracts, at the first time, its frame corresponding to the frame 324; at armature 333 it opens the circuit of electro 338 to stop the selector brushes on the free junction; at armature 334 it disconnects the lower winding of 2-stroke relay 320 from wire 258 thereby opening the circuit of relay 830 in the call controller and it connects the positive talk wire 258 through the brush 347 to 358.



   It will be remembered that the secondary group selector is identical to the primary group selector, the negative talk wire 352 is connected to earth through the two coils of the line relay of the secondary selector while the positive talk wire 358 is open. since the shaft springs of the secondary group selector, identical to the springs

  <Desc / Clms Page number 37>

 S15 and 316 have not yet operated. The positive of the control wire 256 coming from the armature 778 in the call controller causes the 2-stroke relay corresponding to the relay 320 in the secondary selector to operate first to open the secondary selector recall circuit.



   As a result of the attraction of the test relay 330 from the primary selector relay 830 in the call controller releases, at armature 832 it opens the blocking circuit of relay 810. Relay 810 releases if relay 860 is released. at the moment. Following its release, the relay 810 to the armatures 811 and 812 connects the negative and the positive to the wires 352 and 358 by means of the brushes 341 and 347 of the primary selector. The secondary selector line relay draws in series with the call controller relay 830. At armature 813, relay 810 attracts relay 850 again through the first contact and brush 886; to armature 813 it attracts the electro 885 of the OS counting switch again.

   At armature 814, relay 810 opens the blocking circuit of relay 820, but relay 820 remains attracted by armatures 841 and 873, wire 853, brush 915 engaged on the second contact of the bench, the shaft springs 953 and the positive if the third digit has been issued; at armature 815 it again connects earth to wire 793 to attract relay 740 which maintains the release delay characteristic when in the attracted position.



  Relay 850 re-attracts and armature 852 draws electro 910 again to prepare for the advancement of the emission control switch brushes.



   The attraction of the line relay of the secondary selector causes the operation of the electro which

  <Desc / Clms Page number 38>

 Passes the secondary selector brushes over the first grounded group contact at the moment the high resistance winding of the line relay is shorted to cause relay 830 to attract in the manner already described. The relay 830 by attracting, attracts the relay 840, this in turn releases the relay 820. The relay 820 on releasing causes the counting switch CS to advance one step. As soon as the brush 886 engages on the contacts of the grounded multiple bank, the relay 850 remains attracted. At armature 824, relay 820 opens the circuit of relay 830 and the circuit of the line relay of the secondary selector.



  The line relay of the secondary selector releases and advances the electro brushes which engage on the bank contacts to which the primary junctions of the first group end. The relays 830 and 840 of the call controller release and releasing relay 840 causes relay 820 to re-attract. At armature 824, relay 820 again closes the attraction circuit of the line relay of the secondary selector in series with the relay 830. The line relay by attracting causes the advance of the brushes, on the bank contacts, from the first group to the second group of junction, at this moment the high resistance winding of the line relay is short-circuited, when the next group contact is encountered, to cause the attraction of relay 830 as previously described.

   In the same way as that which was previously described the relays 830 and 840 attract, the relay 820 releases to advance the counting switch CS and to release the line relay of the secondary selector and the relays 830 and 840. This cycle group search operations continue until broom 807 of the

  <Desc / Clms Page number 39>

 count switch CS meets the wire grounded by the second register switch RB, in this case wire 5 since the number 5 has been registered by the switch RB. At this moment the secondary selector line relay attracts and advances the brushes to the first junction in the fifth group to start the junction search operation.



  The relays 860 and 810 attract again as described previously and the relay 860 operates the recall of the count switch CS. The relay 810 by attracting blocks the relay 820 in the attracted position and reverses the polarities towards the secondary selector to cause the 2-stroke relay to attract in series with the relay 830 in a manner identical to that which has been described for the primary selector. In an identical manner, the 2-stroke relay of the secondary selector causes the momentary advancement of the brushes in search of a free junction in the group, when this junction is found the test relay, identical to relay 330, attracts and connects the call controller to wires 362, 366 and 368 leading to the connections of FIG. 5.



   Pulling the secondary selector test relay opens the call controller relay 830 circuit which releases relay 830. When the CS count switch reaches its normal position, relay 850 releases to open the call controller block circuit. relay 860 to armature 851, to armature 852 it opens the circuit of the electro 910 which releases and advances the brushes 913 to 915 of the emission control switch on their bank contacts. After a while relay 860 releases and opens the circuit from relay 810 to armature 863. Relay 810 releases when both relays 860 and 830 are released, it will be remembered that the

  <Desc / Clms Page number 40>

 relay 830 releases when the selector engages on a free junction.



   To armatures 811 and 812 relay 810 connects negative and positive to wires 252 and 258 which are now connected through the selector brushes to wires 362 and 368. To armature 813 relay 810 makes relay 850 re-attract by means of brush 886 and causes the electro 885 to be re-attracted by means of armature 822. At armature 814, relay 810 opens the blocking circuit of relay 820 but this relay remains attracted by the positive given by through shaft springs 963, brush 915, wire 853 and armatures 873 and 841. At armature 815 relay 810 reconnects the positive in order to re-attract relay 740 and to start the device again. time.

   Relay 850, by re-attracting, to armature 852 re-attracts electro 910 which is preparing to advance the brushes of emission control switch S.



   The line relay 410 attraction circuit of the connector of FIG. 5 is as follows: positive, lower high resistance winding, upper low resistance winding of relay 410, armatures 441 and 451, wire 362, bank contact and subgroup selector brush to wire 352, bank contact and brush 301 of the primary group selector of fig. 4, NC contact and armature 331, wire 252, brush 277, wire 287, armature 811 and contact closed, wire 784, armature 772, wire 785, armature 824, marginal relay winding 830, negative. Due to the high resistance of the coil of line relay 410, relay 830 does not draw in series with it.

   Connector release relay 460 pulls into wire circuit

  <Desc / Clms Page number 41>

 control as follows: positive to armature 778, armature 751, wire 285, brush 275, wire 256, armature 332 and contact on, broom 343, wire 356, brush and bank contact from secondary selector to wire 366 , normally closed shaft springs 467, relay winding 460, negative. At armature 461, relay 460 prepares the blocking circuit of relay 450; at armature 462 it prepares the circuit of the changeover relay 430; at armature 463 it prepares the blocking circuit of test relay 440; at the frame 464 it is blocked by the grounded control wire 366 independently of the shaft springs 467; at armature 465 it prepares the ringing circuit at one point.

   Line relay 410, attracting, to armature 411 closes the attracting circuit of electro 415; at armature 412 it prepares the automatic control circuit of electro 415 and at one point the shunt circuit of the high resistance winding of line relay 410. The eletro 415 attraction circuit is the following: in contact with the group bench on which the brush 475 is normally engaged, armature 411, contact at rest and armature 425, winding of the electro 415, negative.

   Electro 415 attracts and puts its pawl in the attack position to advance the brushes of the connector, it closes its switch springs 416 to bypass the lower winding of high resistance of line relay 410 as follows: positive via armature 412, switch springs 416 and contact on, lower winding of line relay 410, positive.



   Call controller relay 830 attracts as a result of the change in resistance in wire 362 when the high resistance winding of line relay 410 is bypassed. At armature 831 relay 830

  <Desc / Clms Page number 42>

 again closes the attraction circuit of relay 840 and the latter to the armature 841 opens the circuit of relay 820 which releases. At armature 822, relay 820 opens the circuit of electro 885 of counting switch CS which releases and places its brushes on its first bank contacts; at armature 824 it opens the circuit of line relay 410 and relay 830; to armature 825 it short circuits relay 840.

   In the connector, releasing the line relay 410 opens the circuit of the electro 415 which has the effect of moving the brushes 471, 473, 475 and 477 which engage on their second bank contacts by one step. In the call controller the relays 830 and 840 release as described previously. At armature 841 relay 840 closes the following circuit: positive to shaft springs 963, third bank and brush contact 915 of emission control switch, wire 853, armatures 873 and 841, winding of relay 820, negative . As the operations are identical to those previously described for the primary group selector, the detailed circuits of each relay operation will not be given in full this time.

   Relay 820 to armature 824 again connects the negative through the coil of relay 830 to negative wire 362 to attract the line relay from the connector again. An automatic control circuit is now closed by: the positive on the armature 412 by means of the switch spring 416 and its contact at rest through the winding of the electro 415 and the negative, it causes the advance the brushes of the connector step by step until the brush 475 engages on the eleventh contact which is that of the last line of the first group.

   When the broom 475 reaches its eleventh contact which is grounded to mark the end of the

  <Desc / Clms Page number 43>

 first group and the start of the second group, a circuit closes as follows: bank contact earthed through brush 475, armature 411, contact at rest and armature 425, electro winding 415, negative to maintain the electro 415 attracted. At switch springs 416 and on contact the high resistance winding of line relay 410 is again shorted to attract call controller marginal relay 830 as previously described.

   Relays 830 and 840 pull, relay 820 releases to short relay 840 and to bring count switch CS to its second bank contact group and to open the circuit of line relay 410 and relay 830.



   In the connector, the line relay 410 by releasing at the armature 411 opens the blocking circuit of the electro 415 which releases and advances the brushes of the connector on the first bank contact of the first group. In the call controller the relays 830 and 840 release and the relay 820 draws again through the armature 841. The relay 820 again connects the negative through the relay 830 in series with the line relay 410 , the line relay 410 attracts and at armature 412 closes the direct control circuit of the electro 415 to automatically advance the connector brushes until the brush 475 again encounters a group bank contact set To the earth.

   When the group brush 476 engages the third contact of the grounded group bank, in this case the 21st contact of the bank, the electro 415 is locked in the operated position in the manner previously described. Electro 415 to armature 416 bypasses the high resistance winding of the relay again.

  <Desc / Clms Page number 44>

 line 410 to attract call controller marginal relay 830. Relays 830 and 840 attract again and relay 820 releases to short relay 840 and advance the OS count switch brushes to third position. At armature 824, relay 820 opens the circuit of relays 410 and 830.



  Relays 830 and 840 release and the same cycle of operations is repeated until the stored digit, in this case digit 6, has been found by the CS count switch.



   When the brush 887 of the counting switch meets the wire leading to the stored number 2, the attraction circuit of relay 860 closes as follows: positive to brush 914 of the emission control switch S in position on its third bank contact, brush 954 of the third RC register switch engaged on the bank contact where the N 6 wire contained in the cable 890 ends, the N 6 wire ending in the bank contact and the brush 887 of the CS counting switch, the winding of the relay 860 , the negative.

   Just before the two-contact brush 475 engages on its grounded bank contact, brushes 471, 473 and 477 are placed on their last contact and at the following brushstroke, brushes 471, 473 and 477 are placed on their last contact. release from their bank contacts while the brushes 472, 474 and 478 now engage on the first bank contacts. The last brushes mentioned above are now engaged on the last row of the fifth group while the 475 brush engages the first grounded group bank contact to keep the 415 electro attracted and to short the high resistance. of relay 410. As previously described this results from the attraction of relay 830, the attraction of relay 840 and the release of the

  <Desc / Clms Page number 45>

 relay 830 which releases relay 410 and relay 830.

   Releasing line relay 410 at this time places brushes 472, 474, 475 and 478 on their second bank contact, which in this case are dead pads. The relay 860 by drawing to the armature 861 'again closes the recall circuit of the counting switch CS as previously described; at armature 862 it closes its own blocking circuit; at armature 863 it closes the attraction circuit of relay 810.

   At armature 811, relay 810 connects the positive of armature 771 to negative conversation wire 362; at armature 812 he prepares a circuit to connect the negative through the winding of the marginal relay 830 to the positive talk wire; at armature 814 it prepares the blocking circuit of relay 820; at armature 815 it opens the circuit of relay 740 to trigger the operation of the slow release device; armature 816 prepares its blocking circuit. The relay 820 attracts again following the circuit described above and the armature 823 completes its blocking circuit.

   At armature 824, relay 820 closes the attraction circuit of changeover relay 430 in series with relay 830 as follows: positive to shaft springs 468 which close at the first step of the connector brushes, armature 453 and contact at rest, armature 462 and NO contact, armature 446, upper high resistance winding of relay 430, lower low resistance winding of relay 430, closed contact and armature 455, wire 368, bank contact and secondary group selector brush to wire 358, brush 347, armature 334 and make contact, wire 258, brush 276, wire 286, armature 812 and contact to make, wire 784, armature 772, wire 785, armature 824, marginal relay winding 830, negative .

   As a result

  <Desc / Clms Page number 46>

 Due to the high resistance of the upper winding of the changeover relay 430, the marginal relay 830 does not draw in series with it. At armature 431, relay 430 causes the 2-stroke relay 420 to be drawn at the first time to close only its armature 422 following a circuit borrowing the armature 424 and its contact at rest and the winding of the 2-step relay 420.



  The 2-stroke relay 420 only closes its armature 420 because its upper winding is short-circuited in this bit as follows: positive at armature 431, armature 424 and contact at rest, upper coil of relay 420, armature 422, contact at work 462, contact at rest and armature 453, shaft springs 468, positive.



   In the call controller when the count switch returns to idle relays 850, 860 and 810 release in the manner previously described. At armatures 811 and 812 the relay 810 by releasing reverses the negative and positive polarities of the conversation wires 362 and 368 of the connector thereby opening the circuit of the changeover relay 430 which consequently releases. At armature 814, relay 810 opens the blocking circuit of relay 820, the latter releases and opens the circuit from electro 855 to armature 822 to advance the brooms of the counting switch CS on the first contacts of the bench which keeps the relay 850 attracted through the brush 886 as previously described.



   When relay 430 from connector releases to armature 431 it removes the short circuit from the top winding of 2-stroke relay 420, thereby closing the circuit through both windings of that relay, in series on positive shaft springs 468, to attract relay 420 at second stroke. At the frame

  <Desc / Clms Page number 47>

 421 relay 420 prepares the ringing circuit at one point, at armature 423 it closes the short-circuit of the upper winding of high resistance of change-over relay 430, at armature 424 it prepares the cross-test circuit for / the lower winding of the test relay 440; at armature 425 he prepares the circuit of attraction of electro 415; at armature 426 it prepares the generator return circuit.

   When relay 820 pulls after releasing relay 840 the line relay 410 of the connector is connected again in series with the marginal relay 830 through the armature 824 from where the line relay 410 draws and to the The armature 412 closes, via the armature 425, the circuit for attracting the electro 415 of the connector. The electro 415 attracts and puts its pawl in the attack position to advance the connector brushes, with its switch spring 416 and on contact to work it completes the short-circuit of the lower high resistance winding of the relay line 410 by: armature 412 earthed, switch springs 416 and contact on, lower winding of relay 410.



   The call controller relay 830 attracts as a result of the short circuit of the high resistance winding of line relay 410, at armature 831 it again closes the attraction circuit of relay 840. At the rear - mature 841 relay 840 opens the circuit of relay 820 which therefore releases. Relay 820 releases, at armature 822 it advances the counting switch CS on its second bank contact, at armature 824 it opens the circuit of the two relays 830 and 840, at armature 825 it short-circuits relay 840 again. The line relay of connector 410 releases again, at armature 412 it opens the circuit of electro 415 which releases by

  <Desc / Clms Page number 48>

 consequent and advances the brushes of the connector on the first line of the sixth group. In the call controller relays 830 and 840 release.

   At armature 841, relay 840 again closes the attraction circuit of relay 820; on armature 822, relay 820 makes the electro 855 attract again, on armature 824 it opens the shunt of relay 840 and on armature 824 'it makes line relay 410 re-attract in series with relay 830 In the connector, the line relay 410 by attracting, to the armature 412 causes the electro 415 to attract again. The electro 415 prepares to advance and the connector brushes. At spring 416 / its contact on, it closes the shunt around the high resistance winding of line relay 410 to attract marginal relay 830 of the call controller.



  In the call controller relays 830 and 840 reactivate and relay 820 releases to open the circuit from line relay 410 and the circuit from relay 830 to armature 824, the circuit from shunt relay 840 to armature 825 and to bring the counting switch CS to the third position via armature 822 as described previously. In the connector, releasing the line relay 410 to the armature 412 opens the circuit of the electro 415 which releases and advances the brushes of the connector on the second line of the sixth group. In the call controller, the relays 830 and 840 release and the relay 820 re-attracts.

   The attraction of relay 820 renews the cycle of the operations which have just been described and they / reproduce until the relay 860 of the call controller attracts through the brush 887 because the counting switch CS has encountered wire N 7 of cable 890 which was grounded by the RD recorder, this one having been placed in position at

  <Desc / Clms Page number 49>

 when the subscriber has sent the number 7. The drawing circuit of relay 860 is as follows: at brush 914 of the emission control switch S in position on its fourth bank contact, brush 964 of the recorder RD located on the bank contact of wire N 7 contained in cable 890, seventh bank contact of the counting switch CS to which wire N 7 ends, brush 887, winding of relay 860, negative.

   At armature 861, relay 860 again closes the CS counting switch recall circuit to return the switch to the normal position, i.e. that shown on the plan, at armature 862 it closes its own blocking circuit and to armature 863 it causes relay 810 to re-attract. Relay 810 to armature 814 blocks relay 820, to armature 815 it opens the circuit of relay 740 to restart the slow release device, to armature 816 it closes its own blocking circuit, at armatures 811 and 812 it opens the circuits of line relay 410 and of relay 830. Releasing relay 410 releases electro 415 and brings the connector brushes to the seventh line of the sixth group, in this case this line being the called line.

   In addition, the operation of the armature 812 also closes the attraction circuit of the relay 830 in series with the relay 430 as follows: positive to the operated shaft springs 468, armature 453 and contact at rest, armature 462 and contact at work, armature 446, armature 423, low resistance lower winding of changeover relay 430, closed contact and armature 455, wire 368 and then circuit described previously and comprising wires 358,258, 286,784 and 785, winding of marginal relay 830, negative. At armature 831, relay 830 attracts relay 840 and at armature 832 it closes the

  <Desc / Clms Page number 50>

 blocking circuit of relay 810. Relay 840 attracts but does not currently release the relay
820 because it remains blocked in the attracted position by means of the frames 814 and 825.

   In the connector, the changeover relay 430 attracts and to the armature
431 closes the circuit passing through the armature 424, the lower winding of the test relay 440, the test brush 474 engaged on the test lead which terminates at the called subscriber line. If the called party's line is free, the wire will be connected to the negative through the coil of the line circuit cut-off relay, and through the armature identical to armature 22 and the resistor. tance. In the case where the called line is free, the test relay 440 attracts under the action of the negative on the test wire.

   IL armature 441 relay 440 disconnects line relay 410 from negative talk wire
362, at frames 442 and 445 it closes the ringing circuit; at armature 446 it disconnects the positive of the winding of relay 430 identical to relay 830 of the call controller; at frame 443 it closes its blocking circuit to frame 463 through its upper winding; the armature 444 it grounds the brushes 473 and 474 to occupy the called line and to operate the cutoff relay similar to the cutoff relay 20 of the line circuit. The called line circuit cut-off relay pulls and disconnects the line relay from the called line as well as the positive of the line wires of the called line.



   In the call controller, relay 830 releases, in its armature 832 it unlocks relay 810, if the counting switch has returned to the rest position, and relay 860 releases. Relays 860 and 850, relays
810 and 820 release as previously described. The liberation

  <Desc / Clms Page number 51>

 ration of relay 850, at armature 852 opens the circuit of electro 910 which causes the brushes of the emission control switch S to advance on their fifth bank contacts.

   In this position a circuit closes from the grounded brush 914 through wire 795, through armature 757, wire 796, armature 817, when relay 810 is released, wire 856, the 911 switch springs, the coil of the electro 910 and the negative to attract the electro 910 which advances the brushes of the emission control switch to their sixth bank contacts. As soon as the transmit control switch brush 913 abandons the fifth bank contact the circuit extending through the multiple bank contacts and wire 792 to the controller 720 release relay is opened, thereby causes relay 720 to release after a certain time in order to release the call controller.



   When the brush 913 of the emission control switch S reaches its sixth position, the attraction circuit of the relay 210 closes in the group of secondary junction relays as follows: positive, brush 913 engaged on the sixth contact of the bank, wire 786, armature 774, wire 284, brush 274, relay winding 210, negative. The relay 210 by attracting, to the reinforcements 211, 212, 215 and 216 connects the calling line to the called line following the wires marked by solid lines. At armatures 213 and 214, relay 210 grounds control wires 156 and 256 to maintain the connection and to keep test relay 330 and relay 460 drawn.

   Line relay 220 of the secondary junction relay group is drawn through the caller loop as follows: positive, lower coil of relay 220, armature 215, wire 158, brush 157, wire 117,

  <Desc / Clms Page number 52>

 broom 107, wire 2, caller loop and wire 1, broom 101, wire 111, broom 151, wire 152, armature 212, top winding of line relay 220, negative. The supply current for the conversation is then supplied to the calling subscriber through the two windings of the line relay 220. To the armature 221 the relay 220 connects the ringing tone through the inter - medial of the reinforcements 241 and 221 through the capacitor C and from there following the circuit described above to the line of the calling subscriber.

   In the armature 222 the relay 220 completes the blocking circuit of the relay 210 the to / keep attracted independently of the call controller.



   In the connector the ringing circuit for the called subscriber's call closes due to the attraction of the test relay 440, as follows: generator, lower winding of relay 450, armatures 442 and 421, broom 472, bank contact 67 of the called line, wire 51, line circuit and ringing of the station of the called line, wire 52, bank contact 67, broom 478, armature 426, ON contact and armature 465, armature 445 , positive. When the called subscriber answers the relay 450 attracts according to the circuit described previously, through the loop of the called subscriber, at armature 454 it closes its own blocking circuit by the positive of armature 461 and at through its upper winding.

   At armatures 451 and 455, relay 450 closes the conversation circuit between the lines of subscribers calling and called following the wires marked in full facts, at armature 453 it opens the circuit of the 2-stroke relay which releases and on its contact at work it connects the positive via the shaft springs 468 to the upper winding of the test relay 440 to keep it attracted during the return of the brushes to the normal position.

  <Desc / Clms Page number 53>

 



  The 2-step relay 420, when releasing, at armatures 421 and 426 opens the ringing circuit, at armature 423 it opens the short-circuit of the upper winding of relay 430, at armature 424 it opens the circuit original attraction of test relay 440.

   When the called party answers the relay 230 attracts, after the attraction of the bell cutoff relay 450, following the circuit: positive through the lower winding of the relay 230, armature 216, wire 258, armature 334 and contact on, broom 347, wire 358, broom from the positive line of the secondary group selector to wire 368, armature 455 and contact at work, broom 478, bank contact 67, wire 52, callee's loop and wire 51, contact of bank 67, brush 472, on contact and armature 451, wire 362, bank contact and negative line brush of the secondary group selector, wire 352, broom 341, on contact and armature 331, wire 252, armature 211, winding upper relay 230, negative. Supply current is supplied to the called line through the upper and lower windings of relay 230.

   At armature 231, relay 230 closes the attraction circuit of relay 240. Relay 240 at armature 241 disconnects the ringing tone, at armature 242 it disconnects the earth of counting wire 154 for operate the caller's counter using the brushes 153 and 103; at armature 243 it locks itself to the grounded wire 256 just as it gives a positive to this one by armature 231.



   The connection to the called line is therefore completed, the calling and called subscribers can converse along the circuit marked in solid lines, the call controller is released following the release of the relay 720 in the manner described below.

  <Desc / Clms Page number 54>

 Case of occupation.



   It will now be assumed that either the primary selector or the secondary selector meets all the busy junctions in the selected group. It will be recalled that in these circumstances the relays 810, 820, 830, 850 and 860 of the call controller are drawn.



  If no trunk is available in the selected group, brush 345 or 346 will encounter a grounded group contact on the last trunk in that group.



  If the last junction of this group is free the test relay 330 draws much faster than the electro 338 because the grounded group bank contact will have no effect. However, if the last junction is occupied the grounded bank contact will short the test relay as follows: positive found at the test lead bank contact of the last junction in the group, brush 343, lower relay winding test 370, reinforcements 322 and 311, positive. Since test relay 330 does not attract electro 338 has sufficient time to draw following the circuit: positive at grounded group bank contact, brush 345, armature 326, armature 333, coil of electro 338, negative.

   On the switch spring 339 and its contact on the electro 338 closes the attraction circuit of the relay 310 as follows: positive to the armature 325, switch spring 339 and contact on, lower high resistance winding of the line relay 310 , armature 321 and its contact at work, resistance 327, negative. At armature 311, relay 310 opens the circuit of test relay 330. Under these conditions, relay 830 of the call controller remains engaged in series with the 2-stroke relay 320 and therefore

  <Desc / Clms Page number 55>

 relay 830 to armature 832 keeps relay 810 engaged. Relay 810 to armature 815 holds the circuit of relay 740 open which releases the relay and the weighted armature 741 vibrates for approximately 4 seconds after which the circuit of slow-to-release relay 750 is opened.

   After a while the slow release relay 750 releases and at armature 751 disconnects the positive of wire 285 and control wire 256. At armature 753 the relay 750 connects the busy tone through the Idle contact of armature 753, armature 761, tone capacitor TC, armature 703, wire 622, brush 616, wire 1 and caller loop. At armature 754, relay 750 opens the circuit of relay 770 which releases, at armature 755 it opens its own blocking circuit at one point, at armature 756 it opens the shunt of armature 763.

   Releasing relay 770 by releasing at armature 771 disconnects the positive of wire 252, at armature 772 it disconnects the negative, through the winding of relay 830 of conversation wire 258 to release relay 320 and relay 830 ; at armature 775 it disconnects the capacitor and resistor 729 from the spark arrester; at armature 776 it opens the circuit of relay 790, at armature 777 it opens the original circuit of attraction of relay 780; at armature 778 it disconnects the direct positive from armature 751.



   The relay 320 by releasing at the armature 321 opens the circuit of the line relay 310 which releases, at the armature 322 it opens at a point the circuit of the relay 330 to prevent the operation of this relay during the recall of the brushes; armature 324 closes the brush return circuit in normal position. The brush return circuit in normal position is as follows: to shaft springs 316, armature 324, switch spring 339

  <Desc / Clms Page number 56>

 and contact at rest, armature 333, winding of electro 338, negative. The electro 338 pulls and releases like a vibrator following the circuit described above to advance the brushes step by step until the shaft springs 315 and 316 are open by the time the brushes reach their normal position.



   When the calling subscriber receives busy tone he hangs up his receiver and thereby opens the line relay circuit 730 in the call controller. At armature 731, relay 730 opens the circuit of slow release relay 760 which releases after a certain time.



  At armature 761, relay 760 disconnects the busy tone; at armature 763 it opens the circuit of the slow relay on release 720, at armature 764 it opens the circuit of relay 740 at one point, at armature 765 it opens the circuit of the return relay of the register switch 870 , at armature 766 it opens the circuit of the electro 920 of the sequence switch SS. Relay 870 releases and closes the return circuit to the normal position of all call controller switches. At armature 871, relay 870 disconnects the alternating current source from the primary winding of transformer T and at armature 872 it closes the counting switch CS reset circuit as follows: positive through the winding relay 880, armature 872, shaft springs 883, switch springs 884; winding of electro 885, negative.



  The electro 885 works like a vibrator to advance the counting switch brushes until they reach their rest position, in this position the return circuit is open to the shaft springs 883. At armature 873, relay 870 opens the original circuit of attraction of relay 820, at armature 874 it opens the blocking circuit of relay 840 which releases, at arma-

  <Desc / Clms Page number 57>

 ture 875 it closes the emission control switch return circuit as follows: positive through relay winding 880, armature 875, wire 855, shaft springs 912, switch spring 911, winding of l 'electro 910, negative.

   The electro 910 operates like a vibrator in this circuit and advances the brushes of the emission control switch until the brushes reach their home position, in this position the shaft springs 912 open. At armature 876 relay 870 closes the SS sequence switch return circuit as follows: positive through coil of relay 880, armature 876, wire 857, shaft springs 922, switch springs 921, coil winding 'electro 920, negative. The electro 920 operates like a vibrator to advance the brush 923 step by step until the latter reaches its rest position, in this position the shaft springs 922 are open.

   At armature 877, relay 870 closes the return circuit of the first RA recorder as follows: positive through the winding of relay 880, armature 877, wire 858, shaft springs 932, switch springs 931, winding of the electro 930, negative.



  In an identical manner, the return circuits of the RB, RC, RD recorders are closed by means of the armatures 878,879 and 882 and their respective shaft springs 942, 952,962 and the electros 940, 950,960 to put them back in the rest position. recorder brushes, in this position the shaft springs open the return circuit which keeps the brushes in place. Relay 880 draws in series with the electros of the switches, at armature 881 it earths wire 629 to keep the call controller occupied with respect to the distributor which has access to it.



   The slow relay on release 720 releases soon after

  <Desc / Clms Page number 58>

 the opening of its circuit by the relay 760, at the armature 721 it opens the circuit of the electro 618 at one point, at the armature 722 it opens the blocking circuit of the relays 700 and 710 which release.

   Relay 710 by releasing at armature 711 at another point feeds the circuit of electro 618, at armature 712 it opens at one point the original circuit of attraction of relay 700 and disconnects the positive of wire 115 for release the cutoff relay 20 of the circuit of the calling line; at armature 713 it opens the control circuit of electro 118 at one point, at armature 714 it opens the spark arrester circuit; at armature 715 it prepares the circuit of relay 740 and at armature 716 it disconnects the positive of wire 629 so that the call controller can be seized again if the switches are returned to the rest position and if positive is removed from occupancy test lead 629 to armature 881.



   When the counting switch CS reaches its normal position, relay 850 releases, at armature 851 it opens the blocking circuit of relay 860 which releases. At armature 852, relay 854 opens the circuit of electro 910 to allow the transmission control switch s to be returned to the normal position as described previously.



  Relay 860 when releasing at armature 863 opens the blocking circuit of relay 810 which releases, at armature 814 it opens the circuit of relay 820. All relays release except relay 880 and when all the switches of the controller are When returned to the normal position, relay 880 releases and disconnects the positive of armature 881 from wire 629 to mark that the controller is free and that it can be seized for another call.



   Now consider the case where the connector encounters a busy line instead of a free line:

  <Desc / Clms Page number 59>

 In the event that the line is busy, the brush 474 encounters a grounded bank contact instead of a bank contact to which a negative is connected, therefore the test relay 440 is short-circuited by the positive of the called line test contact and earthed armature 431.

   As the test relay 440 does not attract a circuit closes to keep the relay 830 attracted as follows: positive through shaft springs 468, armature 453 and closed contact, armature 462 and closed contact, armature 446, armature 423, low resistance winding of relay 430, closed contact and armature 455, wire 368, secondary and tertiary switches to wire 258, brush 276, wire 286, armature 812 and contact on, wire 784, armature 772 , wire 785, armature 824, coil of relay 830, negative. Relay 830 is kept attracted by the above circuit, at armature 832 it keeps relay 810 drawn.

   The armature relay 810 keeps the circuit of the relay 740 open, as a result, after about 4 seconds the slow release relay 750 releases to transmit the busy tone to the calling subscriber as previously described. As a result of releasing relay 750, the positive is disconnected from control wires 266 and 366 of armature 751 thereby releasing relays 330 from selectors and 460 from connector. At armature 333, relay 330 closes the return circuit of the primary selector as follows: positive via shaft springs 316, armature 324, switch spring 339 and contact at rest, armature 333, electro winding 338, negative. The secondary selector is returned to standby
 EMI59.1
 even the leme the / manner.

   Relay 460 releases when positive is removed at wire 366, at armature 462 it opens the circuit

  <Desc / Clms Page number 60>

 relays 420 and 430 and closes the connector return circuit. The relays 420 and 430 release and open the circuit of the test relay 440 to prevent its operation during the replacement of the brushes. The return circuit is as follows: grounded shaft springs 468, armature 453 and contact at rest, armature 462 and contact at rest, switch spring 416 and contact at rest, electro winding 415, negative. Electro 415 operates in the manner of a vibrator to return the brushes to the rest position, in this position the shaft springs 468 open the return circuit.



   In the call controller the slow release relay 750 releases shortly after armature 741 no longer makes contact with springs 743 and 744, to transmit the busy tone to the caller as previously described, to the caller. armature 754 it opens the circuit of relay 770, at armature 772 the relay 770 opens the circuit of relay 830 which releases.



   When the caller hears busy tone and hangs up the relays 730,760, 720,870, 840, 710,700, 850, 810, 809 and 880 release as previously described.



   The release of the call controller after establishing a connection between the calling and called lines will be described below. After the connector has moved into position and connected the line called the relays 440, 450 and 460 of the connector are in the pulled position and the relays 210,220, 230 and 240 in the secondary junction relay group are also in the drawn position. It will be recalled that in the call controller the circuit of relay 720 was open as a result of the passage of the brush 913 from the fifth position to the

  <Desc / Clms Page number 61>

 sixth position. Relay 720 by releasing at armature 722 opens the circuit of relays 770, 700 and 710.



  Relay 770 by releasing at armatures 771 and 772 disconnects the negative and positive through the winding of relay 830 of the positive and negative conversation wires in the secondary relay group, at armature 773 it temporarily closes the following circuit: positive to armature 752, wire 288, switch springs 298, electro winding 290, negative; this circuit automatically advances the secondary junction finder brushes until the slow release relay releases; at armature 774 it opens the original attraction circuit of relay 210 kept attracted to armature 222; at armature 775 it opens the spark arrester circuit of the electros of the secondary line seekers, at armature 776 it opens the circuit of relay 790 at one point; at armature 777 it opens the circuit of relay 780 at one point;

   at armature 778 it disconnects the direct positive of wires 285, 256,156 and 356, but wires 156,256 and 356 are now earthed by means of armatures 213 and 214 and armatures 241 and 243. Relay 710 in releasing, at armature 712 disconnects the positive of wires 624 and 115 but the latter is earthed in the group of secondary junction relays through armatures 213 and 214, wire 156, brush 155 to the wire 115 to keep line circuit cutoff relay 20 attracted. At armature 714, relay 710 opens the spark arrester circuit of electro 118; at armature 715 it prepares the circuit of the upper coil of relay 740, at armature 716 it disconnects the positive of wire 629 to make the controller accessible if relay 880 is released at this time.



  Relay 700 by releasing at armature 701 opens the circuit

  <Desc / Clms Page number 62>

 fired relay 780, which releases; at armatures 703 and 704 it opens the circuit of the line relay of controller 730 which releases; at armature 705 it prepares the circuit of relay 710; to the armature 706 it prepares the circuit of attraction of the electro 118. The relay 780 by releasing, to the armature 781 prepares the circuit of the relay 790, to the positive ar- to mature 782 it short- Circuit / armature 791. Line relay from call controller 730 on releasing to armature 731 opens the circuit for relay 760.

   Relay 760, when releasing, at armature 761 opens the tone circuit at one point, at armature 763 it removes the shunt of armature 756; at the armature 764 it opens the circuit of the relay 740 which releases the weighted armature which starts to vibrate between the springs 743 and 744; at armature 765 it opens the circuit of relay 870 and at armature 766 it disconnects the positive of wire 798 to release solenoid 920 of the sequence switch SS.



  Relay 740 on releasing releases the weighted armature 741 which vibrates for approximately 4 seconds after releasing the slow relay on release 760. Relay 870 on releasing at armatures 872, 875, 877, 878, 874 and 882 Closes the OS, S, 3S, RA, RB, RO, and RD switch recall circuits as previously described in series with relay 880. Relay 880 at armature 881 keeps the controller busy until all switches are released by grounding wire 629 to armature 881. When all switches have returned to their normal position and their shaft springs are open as previously described, relay 881 releases to disconnect the positive from wire 629. which allows the call controller to be contacted for subsequent calls.

   From the previous description it can be seen that the call controller is in service during the establishment.

  <Desc / Clms Page number 63>

 Only one connection is made and as soon as the connection has been established between the calling and called subscribers the call controller can be used for further calls.



   The release of a connection established between the calling and called subscribers will now be described. From the previous description it will be remembered that the connection established is maintained by the occupied relays of the group of secondary junction relays. It will now be assumed that the called party hangs up which results in opening the circuit of relay 230 which releases. At armature 231, relay 230 opens the original circuit for attracting relay 240, but the latter remains attracted through the intermediary of the earthed armature 213 and armatures 214 and 243. When the subscriber calling party hangs up line relay 220 circuit of secondary junction relay group is open and releases. At armature 222, relay 220 opens the circuit of relay 210 which releases after a certain time.

   Relay 210 by releasing at armatures 212 and 215 opens the circuit of relay 220 at another point, at armatures 211 and 216 it opens the circuit of relay 230 at another point. At armatures 213 and 214 relay 210 disconnects the relay. positive of wires 156 and 256 to open the blocking circuit of the cut-off relay 20 of the line circuit, of the relay 240 of the secondary junction relay group, of the test relays 330 of the primary and secondary selectors, and of the connector relay 460 . The calling line circuit relay 20 releases and returns the line circuit to the normal position.



  The relay 240 of the secondary junction relay group releases to prepare the call return circuit and to disconnect the positive from the counting wire 154. The relays 330 of the primary and secondary selectors operate their plates 233 to close the recall circuits

  <Desc / Clms Page number 64>

 described above to return the selectors to the normal position. In the connector shown in fig. 5 relay 460 releases and at armature 461 opens the blocking circuit of relay 450. At armature 462 relay 460 prepares the return circuit of the connector and at armature 463 it disconnects one of the positive which maintains the relay of test 440 attracted.

   In the event that the called party has hung up, relay 450 releases and at armature 453 opens the blocking circuit of test relay 440 at its working contact and at its idle contact it completes the connector return circuit as previously described.



  Relay 440 by releasing, to armature 441 reconnects line relay 410 and armature 444 disconnects the positive of wire 53 to release the cut-off relay of the circuit of the called line corresponding to relay 20 of the circuit of the calling line. Due to the closing of the return circuit the electro 415 advances the connector brushes automatically as previously described until the shaft springs 468 are open.



   Releasing the established connection is somewhat different if the caller hangs up first. In this case when the caller hangs up the line relay 220 releases and opens the circuit of the relay 210 to the armature 222. The relay 210, by releasing to the armatures 211 and 215 opens the circuit of the relay 230 which releases. At armature 213, relay 210 disconnects the positive from wire 156 to release cut-off relay 20 from the calling line circuit. Relay 230 on releasing at armature 231 opens the circuit of relay 240 and similarly disconnects the positive of wire 256. Disconnecting the positive of wire 256 causes the release of the selector relay 330 and relay 460 from the connector. The

  <Desc / Clms Page number 65>

 relay 350 of the two selectors again close their return circuit which brings them back to the normal position.



  Relay 460 from the connector releases and at armatures 461 and 465 close a circuit through the called party's loop to keep relay 450 engaged in the event that the called party has not hung up. This circuit is as follows: tif to armature 445, armature 465 and contact at rest, brush 478, wire 52, callee's loop, wire 51, broom 472, contact at rest and armature 461, armature 454, upper winding of relay 450, negative. Relay 450 remains drawn into the calling party's loop until the calling party hangs up. The relay 440 in the same way remains held in position to prevent the seizure of the call controller as if an emitting subscriber has a call.



  When the called party hangs up the circuit of the relay 450 is open which has the result of releasing this relay and the relay 440 and bringing the switch brushes back to rest as described previously.



   Incoming long distance calls.



   For the purpose of describing the operations required for long distance calls between a remote office and a local office, it will be assumed that the called subscriber located at the remote office wishes to call subscriber B of the local office. The switches and devices in the remote office are assumed to be the same as those in the local office just described; placing a call by a subscriber at a remote office places a call controller in service at the remote office. When the caller dials the digits corresponding to the telephone number for extension B, the remote office call controller records the digits.

   As previously described, the call controller retransmits the first digit to a

  <Desc / Clms Page number 66>

 remote office primary group selector which selects a free trunk to the local office. It will be assumed that the junction entered is that shown in fig. 10. In order to more easily describe the operations of the circuit, it will be assumed that the call controller shown in FIGS. 6, 7, 8 and 9 is located at the remote office.



   It will be remembered that when the primary group selector establishes the connection a negative given by the supply relay 830 of the call controller is connected to the corresponding positive wire, in this case the wire 507 following the circuit: negative , winding of relay 830 through armature 824, wire 785, armature 772, wire 784, closed contact and armature 812, wire 286, brush 276, wire 258, test relay armatures corresponding to test relay 330 from the primary group selector at the remote office to the broom 347 or the broom 348 depending on whether one or the other is engaged on the bench contact to which the wire 517 of the junction ends.

   The positive is connected to the negative junction wire 505 in the call controller as follows: positive to armature 771, wire 783, contact on and armature 811, wire 287, brush 277, wire 252, upper armature of the relay test of the primary group selector at the remote office, one of the two brushes 341 or 342 of the group selector at the remote office, bench contact to which jumper wire 505 terminates. As a result of connecting a negative to the positive wire from junction 507 the marginal 2-stroke relay 500 attracts all its reinforcements at the second stroke. At armature 501 the relay 500 disconnects the resistance and the negative of the control wire 506, at armature 502 it locks itself to the grounded control wire 506 before the armature.

  <Desc / Clms Page number 67>

 ture 503 opens its original circuit of attraction.



     Shortly after the pull of relay 830 to the remote office, the call controller relays pull in the manner previously described to reverse the polarities of the negative and positive wires 505 and 507. As said before, the relays 510 and 520 are polarized relays. , they attract only if they are traversed by a current flowing in a certain direction.

   At the moment the circuit of attraction of the polarized relay 502 is as follows: tif to armature 771, wire 783, contact at rest and armature 812, wire 286, brush 276, wire 258, armature of the test relay and primary group selector brush through wire 507, lower left winding of RC translator coil, winding of polarized relay 510, high resistance 512, winding of polarized relay 520, upper left winding of RC translator coil, wire 505, broom and primary group selector test relay armature to wire 252, brush 277, wire 287, armature 311 and closed contact, wire 784, armature 772, wire 785, armature 824, relay winding 830, negative.



  As a result of the high resistance 512 the relay 830 does not attract according to this circuit and the polarized relay 510 does not attract either because the direction of the current is opposite to that which attracts the relay 510. The polarized relay 520 attracts however. in the circuit described above and to the armature 521 it completes the attraction circuit of the relay 550. The relay 550 by attracting to the armatures 551 and 553 reverses the line wires 562 and 568 with respect to the negative and positive wires of the receiver.

   At armature 552 the relay 550 closes the attraction circuit of relay 540, and at armature 552 also it connects the negative to wire 562 to make the line relay of the secondary group relay attract as follows: by

  <Desc / Clms Page number 68>

 through the closed contact of the upper armature of the 2-step relay of the secondary group selector, lower high resistance winding of the line relay of the secondary selector, armature of the 2-step relay corresponding to armature 323, winding low resistance top of the line relay, idle contact and armature corresponding to armature 331, wire 562, armature 551 and contact to work, upper right winding of the RC translating coil, upper winding of marginal relay 530, armature 522, negative.

   Due to the high resistance of the line relay winding the repeater marginal relay 530 will not draw in series with it. The secondary group selector line relay, however, attracts to operate the secondary group selector in the manner previously described for the primary group selector. Relay 540 by pulling to armature 541 grounds control wire 566 to cause the secondary group selector 2-step relay to attract at first step in a manner similar to that previously described. The 2-step relay of the secondary group selector shown in fig. 10 corresponding to the relay 320 attracts and operates only its armature 324 to open the return circuit.

   The attraction of the line relay of the secondary group selector closes the electro circuit of this one, it puts its pawl in the brushes attack position and its switch springs open its own circuit in the event that the brush of the secondary selector in fig. 10 is not engaged on a grounded bank contact. When the secondary selector brush engages a grounded bank contact the high resistance lower winding of the line relay is shorted to allow the repeater marginal relay 530 to attract.

  <Desc / Clms Page number 69>

 this circuit it will be assumed that the primary selector shown in fig. 4 is in the current example the secondary group selector shown in fig. 10.

   In this case the attraction circuit of the repeater marginal relay 530 is as follows: positive at armature 312, switch spring 339 and its contact on, armature 323, upper winding of low resistance of line relay 310, contact on rest and armature 331, wire 562, armature 551 and contact on, upper right winding of RC translating coil, upper winding of marginal relay 530, armature 552, negative. Relay 530 by pulling armature 531 bypasses high resistance 512, thereby allowing the pull of marginal relay 830 of the controller following the circuit described above. The call controller relays now perform the group hunt cycle and the secondary selector operates from group to group as previously described.

   It is understood, in fact, that each time a grounded group bank contact is encountered by the brush of the secondary selector the high resistance winding of the line relay is short-circuited which has the effect of to attract the repeater relay 530 which short-circuits the resistor 512 which makes it possible to attract the relay 830 of the call controller. The call controller's CS count switch operates step by step whenever the secondary selector encounters a bank contact and when the switch encounters the marked contact, determined by the stored digit, the call controller's relay 860 will draw for operate the inversion relay 810 of the call controller.

   At armatures 811 and 812, relay 810 reverses the positive and negative connections of the negative and positive wires 505 and 507 which has the effect of

  <Desc / Clms Page number 70>

 attract the polarized relay 510 instead of the relay 520, the latter releases. The relay 510 by attracting, to the armatare 510 keeps the circuit of the relay 540 closed, it also keeps the negative connected to the upper talk wire of the junction. The polarized relay 520 when releasing, the armature 521 opens the circuit of the changeover relay which releases.

   On armatures 551 and 553, relay 550 reverses the negative and positive of wires 562 and 568 to attract the 2-stroke relay 320 as follows: positive to the operated shaft springs of the secondary group selector, lower coil of the relay at 2 times and springs normally closed controlled by the lower armature of the marginal test relay, wire 568, armature 553 and contact at rest, upper right winding of the RC translator coil, upper winding of the marginal relay 530, armature 511, negative. Relay 530 and the group selector 2-step relay attract following the circuit described above.

   The 2-step relay of the secondary selector attracts and sets the brushes in motion automatically as described previously for the primary group selector until a free connector is reached, at this time the test relay of the corresponding secondary group selector to test relay 330 operates to establish the connection to the connector. At the lower armature of the secondary group selector test relay the 2-step relay and repeater relay 530 circuit is open. Relay 530 on releasing to armature 531 removes the short of high resistance 512 to release call controller relay 830. Call controller relay 830 is a marginal relay, it does not stay pulled when connected in series with high resistance 512.

   When the controller OS count switch

  <Desc / Clms Page number 71>

 is brought back to rest as a result of the attraction of relay 860 as previously described, relays 850,860, 810, 820 and 840 release. Relay 820 releases and at this time since relay 810 is not released the negative is connected through the coil of relay 830 to the coil of line relay 410 via wire 362, in effect assuming that the connector of fig. 5 is the connector that was selected by the subgroup selector.



   From the above it can be seen that the repeater repeats to the call controller the resistance modification when each grounded group bank contact is encountered by the selector brush; as a result of the attraction of relay 530 which, by shorting resistor 512, causes the attraction of relay 830 of the controller. Repeater polarized relays 510 and 520 and repeater relay 550 repeat the reverse polarity on wires 562 and 568 to the secondary selector. In addition, when the selector establishes the connection, the circuit of the relay 530 opens and the latter releases to open the short-circuit of the resistor which releases the relay 830 of the call controller.

   The repeater thereby repeats on the two-wire junction between the two offices the changes in the circuit so that the controller and switches operate the same as if the controller and the switch train were in the same office.



   The repeater operates in the same way as described for establishing the connection. The incoming repeater works on the loop line coming from the remote office, it repeats the two polarities used to control the secondary group selector and connector.

   The connector shown in fig 5 now operates.

  <Desc / Clms Page number 72>

 as described above under the action of remote office call controller and inbound repeater operations. when the called party answers the call, relay 450 connects the called line to wires 362 and 368 completing the repeater relay 530 draw circuit as follows:

   positive through the lower winding of the relay 530, lower right winding of the RG translator coil, make contact and armature 553, wire 568, positive talk brush of the secondary group selector, wire 368, talk circuit marked in solid lines as described above, loop of the called station, wire 362, negative conversation brush of the secondary group selector, wire 562, armature 551 and contact on, upper right winding of the RC translator coil, upper winding of the relay 530, frame 552, negative.



   Referring to the call controller it will be remembered, as previously described, that when the test relay 440 has drawn to connect the inrush current to the called line, this relay to the armature 446 has Open the circuit of the call controller relay 830, the relay 830 therefore releases. Likewise, relays 850 and 860 release when counting switch CS returns to the rest position, then relays 810 and 820 release. Releasing relay 850 to armature 852 moves control switch S to the fifth position. The brush 914 of the emission control switch S in the fifth position causes the brushes of the switch S to advance to the sixth position as described above.

   Sweeper 913 on relinquishing its fifth position opens the circuit of release relay 720 to release the call controller as previously described. The switch brush 913

  <Desc / Clms Page number 73>

 S transmission control switch in the sixth position closes the release relay circuit of the remote office secondary junction relay group, corresponding to relay 210. Now assuming that the secondary junction relay group of FIG. 3 is the remote office relay group, the operation of relay 210 is seen to interconnect the calling and called lines, draw line relay 220 into the calling loop, ground control wires 156 and 256 to maintain connection as previously described.

   Looking now at the point when the secondary trunk relay group establishes the connection of the calling and called lines and the call controller is disconnected we see that a circuit closes to keep the bias relay 520 attracted, as follows: marginal relay 230 lower winding, armature 216, wire 258, talk lead positive and talk brush positive from primary group selector to lead 507, lower left winding of RC translator coil, polarized relay winding 510, high resistance 512 , polarized relay winding 520, upper left winding of the RC translator coil, jumper wire 505, negative talk brush of primary group selector, negative talk wire of primary group selector, wire 252, armature 211,

   upper winding of relay 230, negative. The relay 230 does not attract following the above circuit due to the presence in this circuit of the high resistance 512. The relay 520 however remains attracted in this circuit to the armature 521 it keeps the relay 550 attracted.



  When the called party answers and the repeater relay 530 draws as described previously, this relay to the armature

  <Desc / Clms Page number 74>

 531 again short-circuits resistor 521, thereby attracting relay 230 of the secondary junction relay group which in turn pulls relay 240 to armature 231. Power is supplied to the armature. the caller through the windings of the relay 220 following the conversation wires shown in solid lines, the supply current is supplied to the called party through the windings of the repeater relay 530 and following the conversation wires marked in solid lines .



   The release of the established connection is controlled by the secondary trunk relay group in much the same way as already described. The relay 220 releases when the calling subscriber hangs up, at armature 222 it opens the circuit of release relay 210. The release relay 210 by pulling, at armatures 213 and 214 disconnects the positive of control wires 156 and 256. at armatures 211 and 216 it opens the circuit of relays 230 and 520. The polarized relay 520 by releasing at armature 521 opens the release circuit of relay 550 which releases. At armature 552, relay 550 opens the circuit of relay 540 which releases.



  At armature 541 the relay 540 disconnects the positive from the control wire 556 to cause the release of the secondary selector and the connector in the manner previously described.



   If the secondary selector encounters all the occupied junctions, it stops on the last junction of the group where the brush is engaged on a group contact that is earthed. As described above, the electro remains attracted to bypass the high resistance of the line relay winding, it then maintains the repeater relay 530 in the attracted position. Relay 530 thereby maintains the short

  <Desc / Clms Page number 75>

 circuit of the resistor 512 and therefore the relay 830 of the call controller remains activated. Relay 830 ci keeps relay 810 engaged, armature 815 keeps relay 740 circuit open to cause relay 750 to release and to transmit busy tone to the caller as previously described. .

   Relay 750 at armature 751 disconnects the positive from control wire 506 to release relay 500 and at armature 754 it opens the circuit of relay 770 which releases. At armatures 771 and 772, relay 770 disconnects the positive and negative of wires 505 and 507 to release relay 510. Relay 510 when releasing opens the circuit of relay 540. Relay 540 when releasing at armature 541 disconnects positive from control wire 566 to release secondary selector as previously described.



   In the event that the connector encounters a busy line it operates as stated previously and in the present case since the test relay 440 does not operate, the positive of the shaft springs 468 holds the following drawn relay 530. the circuit: via the shaft springs 468, armature 453 and contact at rest, armature 462 and contact on, armature 446, armature 423, lower winding of relay 430, contact at rest and armature 445, wire 338, lower winding and lower wire of the secondary group selector, wire 568, armature 553 and closed contact, upper left winding of the translator coil, upper winding of the marginal relay 530, armature 511, negative.

   At armature 531, relay 530 holds the short circuit of resistor 512 to block relay 830 of the call controller.



  Relay 530 keeps relay 810 attracted and re-energizes it.

  <Desc / Clms Page number 76>

 But 810 in turn, armature 815 keeps the circuit of relay 740 open. Relay 740 releases and after a while relays 750 and 770 release as previously described. As has been said, relay 750 transmits the busy tone to the calling subscriber and opens the circuit of relay 500 which releases. Relay 770 opens the circuit of polarized relay 510 which releases and opens the circuit of relay 540. Relay 540 on releasing at armature 541 disconnects the positive from control wire 566 to release the secondary selector and connector as previously described.

   When the caller hears the busy tone transmitted to him by the call controller, he hangs up his receiver and releases the controller as described previously.


    

Claims (1)

CLAIMS. 1. A telephone system using automatic switches having access to groups of lines in which during the establishment of a connection each digital switch entered performs an automatic movement in each group until the required group is reached and in which as soon as the automatic movement is finished a signal is transmitted to common devices which control the establishment of the connection, the beginning of the automatic movement in each successive group being controlled by the common digits under the action of such signals, until 'until the required group is reached. 2. A telephone system using automatic switches having access to groups of lines in which during the establishment of a connection each digital switch entered performs an automatic movement in each group until the required group is reached, for each automatic movement A change in resistance occurs in a circuit connecting the switch to a common switchgear which controls the establishment of the connection, each change in resistance being used to operate a common switchgear counting mechanism to determine whether the movement Automatic switch in groups should continue or stop. 3. A telephone system using automatic switches having access to groups of lines in which during the establishment of a connection each digital switch entered performs an automatic movement in each group to a certain conductor of a circuit coming from. common equipment, <Desc / Clms Page number 78> it serves to control the establishment of the connection while the transfer of a polarity from said conductor to a second conductor of the circuit is effected when the required group is reached to prepare the subsequent movement of the switch. 4. For use in a telephone system, an automatic switch which performs step-by-step movement through individual lines or groups of lines to which it has access, switching the switch from one line or group to another. 'the other being indicated by the variation of resistance produced in a circuit leading to the common apparatus provided for the control of the establishment of the connection, these signals being counted by the common apparatus to determine the continuation or the stop of the movement - step by step. 5. A telephone system in which each group of lines is associated with a certain number of primary searchers while controllers, common for a certain number of groups of lines, are provided for establishing the connection and in which when a line in one of the groups makes a call, a recorder controller is entered, it puts into service a searcher specific to the recorder and having access to the searchers associated with the groups of lines which have the recorder in common , this searcher selects a free primary searcher having access to the group of lines containing the calling line and causes the search for the calling line by the selected primary searcher. 6. A telephone system having primary and secondary seekers for establishing the connection with a primary digital switch in <Desc / Clms Page number 79> which is provided for a distributor common to the primary and secondary searchers intended to control the selection of a primary searcher having access to the calling line, the search for the calling line by the searcher, the selection of a free secondary switch and the search, by the selected secondary switch, for the selected primary finder. 7. For use in a retort telephone system claimed in claim 1, a group selector which when entered performs automatic movement in each group up to µ. that the required group is reached and that, when the automatic movement in a group is finished, transmits a signal to the common apparatus which controls the establishment of the connection, the beginning of the automatic movement in each successive group being controlled by the common switchgear under the action of these signals until the desired group is reached, in this name the common switchgear exercises another control of the switch which goes on -, looking for an 11; ::; not free in the selected group. 8. For use in a telephone system as claimed in claim 1, a final selector which when entered performs automatic movement in each group until the required group is reached and which when the movement automatic movement in a group is finished, transmits a signal to the common apparatus which controls the establishment of the connection, the beginning of the automatic movement in each successive group being controlled by the common apparatus under the action of these signals until the desired group is reached, at the moment the common switchgear is controlling <Desc / Clms Page number 80> different from the switch which causes a step-by-step movement through the individual lines of the group under the control of the common apparatus until the desired line is reached, at each step the switch sends a signal to the common apparatus, which, under the action of this, causes the switch to advance one step until the required line is reached. 9. For use in a telephone system as claimed in claim 3 a group selector which when entered performs automatic movement in each group until the required group is reached and which when the movement automatic movement in a group is finished, transmits a signal to the common apparatus which controls the establishment of the connection, the beginning of the automatic movement in each successive group being controlled by the common apparatus under the action of these signals until the desired group is reached, and to search for a free line in the selected group. 16. Oven for use in a telephone system as claimed in claim 3 is a final selector which when entered performs automatic movement in each group until the required group is reached and which when automatic movement is reached. in a group is terminated, sends a signal to the common apparatus which controls the establishment of the connection, the beginning of automatic brooding in each successive group being controlled by the common apparatus under the action of these signals until until the desired group is reached, and day prepare the switch for <Desc / Clms Page number 81> the selection of the desired line in the group, therefore polarity is established on the conductor press to allow advancement of the switch on the individual lines of the group under the control of the common apparatus until the required line is reached. 11. A telephone system as claimed in Claim 1 in which the signal comprises a change in the resistance of the circuit connecting the switch to the common apparatus. 12. A telephone system as claimed in claim 7 or 8 in which the signal comprises disconnecting the negative of one conductor and connecting it to a second conductor of the circuit connecting the switch and the common apparatus. 13. A telephone system as claimed in one of the preceding claims in which the circuit connecting the switch and the common apparatus comprises the conversation wires. 14. A telephone system as claimed in claim 2, 4 or 13 in which the variation of the resistance of the circuit is effected by shorting the high resistance winding of a relay forming part of the switch. 15. A telephone system as claimed in claim 14 in which the high resistance winding is shorted by the contact made of the switch springs associated with the switch control solenoid. 16. A telephone system as claimed in claim 1, 2, 3, 4, 7 or 8 in which the common apparatus comprises a recording controller which records the digits sent by the calling subscriber. <Desc / Clms Page number 82> and sends them back unchanged to the automatic switches. 17. A telephone system as claimed in claim 16 in which when the recorder is entered a searcher associated therewith performs a search operation to connect the controller to a group selector through a group. relay that maintains the connection and controls the application of the power source to the calling and called subscribers. the. A telephone system as claimed in claim 17 in which when the connection is made to the called line the registrar controller is disconnected from the relay group. 19. A telephone system as claimed in claim 1, 2, 3 or 4 in which if any of the switches encounters a busy line, the seized switches are released and the busy tone transmitted to the caller by. common equipment. 20. A telephone system as claimed in claim 2, 3, 4, 11 or 12 in which for inter-calls a repeater is provided to repeat the variations in resistance from the outgoing circuit to the incoming circuit and to repeat the polarity reversals of the incoming circuit to the outgoing circuit. 21. A telephone system as claimed in claim 3, 4, 6, 8, 9 or 11 in which reversing devices are provided in the switches which under the action of the received signal perform a search movement. automatic or step-by-step movement on individual lines. 22. A telephone system as claimed in one <Desc / Clms Page number 83> any one of the preceding claims wherein the switches used for establishing the communication are single motion switches. 23. A telephone system as claimed in claim 5 in which the calling line is extended to digital switches through secondary line seekers having access to all primary line seekers via primary trunks, a finder associated with the recording controller serving to select a free secondary line finder and causing the selected secondary line finder to search for the selected primary line finder. 24. A telephone system as claimed in claim 6 or 23 in which only the control appliances are associated with the researchers. 25. A telephone system as claimed in claim 24 in which the spark arrestor circuits are common and distributed by the recorder. 26. A telephone system as claimed in claim 5 in which the recorder is operated through a distributor which advances to select another recorder when a free primary seeker has been found. 27. A telephone system as claimed in claim 23 in which the selected primary junction is marked with AC current, when this junction is entered by the secondary line finder it causes a current relay to operate. alternative in Itenregister to stop the search. 28. A telephone system in principle as described <Desc / Clms Page number 84> and shown in the attached plans. 29. To be used in an automatic telephone system switches, in principle, as described and shown in the accompanying drawings.