Patent GB-229651-A (GB)
Title: Improvements in or relating to automatic telephone systems
IPC: H04Q3/42
Filed: 1925-02-11
Abstract: 229,651. Lenaghan, T. Feb. 21, 1924, [Convention date]. Automatic exchange systems; party line systems; metering; selectors. - In a system using power-driven selectors which hunt for an idle one of a marked wanted group of lines, or for a marked wanted line, the complete number is recorded on a register-controller, which, as the connection advances, transfers its records to marking switches at each connecting stage. The registercontrollers or marking switches are associated with groups of outgoing trunks, provision being made whereby a register-controller or marking switch is not taken into use if all the associated trunks are busy. When seeking for an idle trunk in a wanted group, if all the trunks in the group are found engaged, the search is repeated an arbitrary number of times. The invention is described with reference to two systems, a 20,000- line system using vertical bank panel switches, and a 12,000-line system using rotary bank panel switches. In the first system, the register-controller connects itself directly to the calling line and itself marks out part of the connection, whilst in the second system, the register-controller connects itself to a first selector trunk and progressively transfers all its records to marking switches at the different connecting stages. Operation of system shown in Figs. 2 to 6. All the selectors in the talking connection are panel selectors constructed as hunting switches, groups of trunks or individual lines being selected by marking wire circuits. The system has a capacity of 20,000 lines. A calling party is connected over a brush-set CRS, Figs. 2 and 5, on the linepanel, to an idle register-controller CR preselected by a switch MS, and by an outgoing brush-set OTC1, Fig. 2, on the line panel, preselected by a switch MS1 and associated with an idle brush-set OTC2 of an intermediate panel. The register-controller CR is now set by the dialling impulses, part of its digit record being used to mark out a group of trunks to the wanted 500- line exchange section of an intermediate panel. The engaged brush-set OTC2 hunts for an idle trunk in the marked group, and the unused digit records of the register-controller CR are transferred to an idle register CRP, Fig. 3, associated with the engaged trunk by a master switch MS2. The register-controller CR is then released and the wanted line marked out by the register CRP, after which a selected incoming brush-set 1TC serving the sub-group to which the wanted subscriber belongs, hunts for the marked line, the register CRP being released when the wanted line is engaged. Construction of panel switches, Fig. 7. These are slightly modified forms of the panel switch described in Specification 189,822. The brush-sets are permanently coupled to the lifting members 47 but are selectively tripped by staggered catches 57 on rods 41 rotated together by friction-discs 54 engaging with driving discs 55 on a shaft 56. The rods 41 carry wipers A<2>, one of which, at a rotary position corresponding to the brush-set it is desired to trip, completes a circuit over a contact A for a magnet CTI mounted on the rod 41, which is thereby raised to trip the desired brushset. The change-speed means described in the before-mentioned Specification is dispensed with. The angular motion given to the lifting member 47 to couple it to the driving blades 29 is transmitted from the magnet TMI by a chain 58 or other flexible connecting-means. Connection of calling line to an idle registercontroller, Fig. 5. On the calling party removing his receiver, the line relay 29 partially operates, earthing the marking terminals T of the calling line in the panel, and a pilot relay 101 closes an alarm circuit over a pilot lamp 103 and energizes a relay 105, which clutches in the switch-driving mechanism. The pilot relay 101 also earths a tripping rod contact 110 (A, Fig. 7) of all the brush-sets serving the panel bank containing the calling line, the tripping magnet CT4 of the brushset CRS associated with the first idle registercontroller only being energized over an arm of a protecting switch MS. The magnet CT4 also energizes the corresponding clutch magnet TM4, which causes the selected brush-set CRS to be raised until the marked calling line is engaged, when the magnet TM4 is short-circuited and the lifting mechanism declutched. At the commencement of the lifting movement, the preselecting switch magnet 117 is energized over the off-normal springs NS22 and moves the switch to the next idle register-controller. Dialling tone is impressed on the calling line over the transformer 140, battery at the secondary winding of which (1) energizes a relay 112a which fully operates the line relay 29, and (2) energizes an impulse relay 111, de-energizations of which in response to the dialling impulses set the recorder in known manner. Connection of calling line to an idle brush-set on the intermediate panel, Fig. 2. On the transmission of the third impulse series a circuit is completed at contacts 54, Fig. 2, for the tripping magnet CT3 of an outgoing brush-set OTC1 serving the panel bank containing the calling line and connected to an idle row of brush-sets on the intermediate panel associated with the registercontroller CR over a switch MS1, the tripping magnet CT3 of the brush-set serving the same panel bank as the register-controller brush-set CRS, being selected over tripping-rod contacts A<3> of the register-controller brush-set. The tripping magnet CT3 also energizes the clutch magnet TM3, and on the brush-set OTC1 engaging the calling line, a finger 59 on the lifting member engages a contact 56 connected to a contact 55 earthed over a similar finger 58 on the lifting member of the register-controller brush-set CRS, thereby short-circuiting the clutch magnet TM3 and arresting the brush-set OTC1. A holding relay 53 has meanwhile been energized over the holding wire H earthed by the relay 112<a>, Fig. 5, at the register-controller CR. Each of the five banks of the intermediate, panel are allotted to main trunking groups to a 4000-line section of the exchange, these main groups being divided into minor groups to 1000-line sections, and the minor groups being subdivided into subgroups to the 500-line sections. The trip magnet CT1 of the brush-set OTC2 serving the wanted 4000-line section is energized over the wiper ID of the register-controller sequence switch in its first position, the ten thousands digit wiper F (set by the first digit) and a selectable contact A1 engaged by the tripping-rod wiper A<2> of the brush-set OTC2. The trip magnet CT1 energizes its clutch magnet TM1 and the sequence switch magnet SM1, which moves the sequence switch to its second position, in which the thousands and hundreds digit wipers, set on the register banks B, C by the second and third digits, are earthed. In accordance with the setting of the wiper on the bank A a marking wire to the wanted 1000-line group is earthed, and depending upon whether a change-over relay x is or is not energized over the wiper on the bank C, the earthed marking wire is extended to the marking terminals T of the wanted 500-line subgroup. When the brush-set OTC2 engaged the first trunk in the marked subgroup, if this trunk is idle the magnet TM1 is short-circuited, arrests the brush-set, and drives the sequence switch to its third position, but if the first trunk is busy earth on the test terminal H holds the magnet TM1 over its second winding, and the next trunk is similarly tested. If all the trunks in the wanted subgroup are engaged the brush-set is lifted to the top of the bank where the springs NS2 are opened, de-energizing the magnet TM1 and causing the brush-carriage to drop to normal, the closure of the normal springs NS1 completing a circuit for the sequence switch release magnet RRM. The selecting operations are now repeated as before until a trunk becomes disengaged or until the calling party hangs up. Each time the sequence switch wiper IE passes over its second contact, the second magnet K<1> of a switch is energized, which advances a wiper K<2> a step until at the fifth repetition busy tone K<3> is connected to the calling line over conductor 148. Preventing the engagement of a register-controller all the outgoing trunks associated with which are busy. Off-normal contacts 143, Fig. 2, of the brush-groups of all the trunks associated with a register-controller are included in a series circuit to a test contact of the master-switch magnet 117, Fig. 5, in order that if all such trunks are engaged the switch MS moves to the next idle register-controller. Transfer of the remaining register records to the register CRP, Fig. 3, at the wanted exchange section and release of register controller CR. Fig. 2. On the engagement of the outgoing trunk TS, Fig. 3, the extension of the earthed holding wire H energizes a relay 70, which closes a circuit for the driving magnet 61 of a switch MS2 which associates the register CRP at the wanted section with the trunk TS. The response of the test relay 62 when the trunk TS is engaged, de-energizes the magnet 61 and energizes a relay B<8> which places holding earth on wire H and busy earth on all the remaining trunks associated with the register CRP. The relav 62 also completes a circuit over lead 85 (see Fig. 5) and the wire L for an impulse-receiving relay 120, Fig. 5, at the register CRP, and a circuit over leads 86, T for a relay 113 at the register-controller CR, Fig. 2, the latter relay closing a driving circuit over lead 146 for the sequence switch SM1, Fig. 2, which moves to its fourth position, in which a circuit is completed over the register wiper engaging bank CA (which wiper is moved with the hundreds wiper) and lead 148, for the impulse-transmitting relay 147, Fig. 5, to which impulses corresponding to the setting of the wiper CA are transmitted as described in Specification 214,861. The relay 147 transfers the