Patent GB-181705-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1922-06-07
Abstract: 181,705. Western Electric Go., Ltd., (Assignees of Williams, S. B.). June 16, 1921, [Convention date]. Automatic exchange systems.-In a by-path system a registering and controlling equipment comprises line-markers for different groups of wanted lines, and cross-bar switches are used to make the talking connection. In the system described, a calling line 100, Fig. 1, is extended by a primary cross-bar switch PS to an idle trunk 200, say, which is extended by a secondary crossbar switch SS, Fig. 2, to an idle trunk 300 having a repeater 344. The trunk 300 is connected by a sender-selector cross-bar switch SNS to an idle impulse-responder, thousands-marker, and line marker, Figs. 4, 5, and 6. The thousands-marker takes into use an idle trunk 3000, Fig. 3, to which the trunk 300 is extended by the cross-bar thousands selector TS. The line marker of the wanted thousands group is of the relay selector type and selects and tests the wanted line 101, Fig. 1, say, which, if idle, is extended through primary and secondary switches PS, SS and an incoming trunk selector ITS, Fig. 2, to the trunk 3000. The trunks in any particular numerical group may be physically intermingled with those in other groups; thus in the thousands selector TS, Fig. 3, the switch bar 348 of one group is between the bars 341, 349 of another group, the starting-circuit 508 for the group 341, 349 &c. being extended, if bar 341. is in use, over the front contact of relay 339 to the magnet operating bar 349. Switches 124, Fig. 1, 224, 229, Fig. 2, are moved forward one step when a trunk is taken into use and vary the order of preference. Connection of calling line 100 to idle trunks 200, 300 and marking equipment. When the subscriber 100 removes his receiver, line relay 104 closes a circuit through the right winding of the cross-bar magnet 102 (which does not energize owing to the resistance in circuit) and left winding of relay 104 for a relay 108, which energises a relay 107, which locks up over a relay 110. Relay 110 energizes a relay 116 which closes over a contact of switch 124, the circuit of the magnet 120 of the vertical bar corresponding to an idle trunk 200. The magnet 120 looks up over the left-hand winding of a relay 115, which does not energize at this stage as it is short-circuited. The relay 110 also energizes in succession a combination of slow release relays 119, 118, 117, which send an impulse through a magnet 113, thus stepping on the switch 124 to change the order of preference of the trunks 200, 201, &c. The magnet 120 energizes over wire 126 a trunk relay 204, which operates like the line relay 104, Fig. 1, to cause the selection of an idle trunk 300, the vertical bar magnet 220 of which locks up over the left-hand winding of relay 215 and energizes over wire 226 a trunk relay 304. Fig. 3. The relay 304 similarly brings about the selection of an idle impulse responder and marking equipment, the magnet 320 of the sender selector SNS being energized. Magnet 320 locks up over the right-hand winding of relay 315, which like the relays 215, @15 is short-circuited at this stage. The slow-release relays 317, 319 (acting like relays 117, 118, 119 and 217, 218, 219) send an impulse through magnet 313 to move on the switch 324. The magnet 320 energizes a slow-release relay 321, which opens the first energizing circuit of magnet 320 and removes the short-circuit around relay 315, which energizes and completes a circuit for the cross-bar magnet 302, through the lefthand windings of relays 304, 315. A relay 330, in parallel with magnet 302, disconnects the repeater 344 from the calling trunk. Magnet 302 extends the trunk 300 to the sender and completes a holding-circuit through both its windings in series dependent on the sender relay 500. Magnet 320 is de-energized, the cross-bar contacts being maintained by magnet 302 alone. Magnet 302 also energizes relay 306 to restore the common control relays 307, 315, &c., and energizes relay 331, which in turn energizes relay 221, Fig. 2. Relay 221 opens the energizing-circuit of magnet 220, and removes the short-circuit around relay 215, which energizes in series with the right-hand windings of magnet 202 and relay 204. Magnet 202 (1) extends trunk 200 to trunk 300, (2) completes a holding-circuit through both its windings in series dependent on relay 221, and (3) energizes relay 206 to restore relays 207, 215, &c. Relay 221 also energizes relay 121, Fig. 1, which opens the energizing-circuit of magnet 120, and removes the short-circuit around relay 115, which energizes in series with the right-hand winding of magnet 102 and the left-hand winding of relay 104. Magnet 102 (1) energizes relay 106 to restore the relays 104, 107, 115, &c., (2) completes a holding-circuit for itself dependent on relay 221, and (3) extends the calling line over trunks 200, 300, and the sender selector SNS to the impulse relay 405, Fig. 4, controlling the marking equipment. Relay 405 energizes a slowrelease relay 400 which maintains the circuit of relay 321. Impulse responder and marking equipment. This comprises a register, which records the whole number of the wanted line, a thousands marker, and a line marker. Successive sets of impulses are repeated by the relay 405 to the magnets 502, 509, 513, 514 over arm 501 of a distributing switch operated by magnet 505 which is energized during each set of impulses by a slow-release relay 504. The switch arm 507, operated by the thousands magnet 502, prepares a circuit over one of the thousands marking wires 508 to cause the selection of an idle trunk 3000 in the desired thousands group, which is connected to the trunk 300 by the thousands selector TS. The switch-arm 515 prepares a circuit to associate the line marker of the same thousands group with the register. The line marker is set by the register in accordance with the last three digits, and comprises three sets of relays shown in the upper part of Fig. 6, there being ten relays such as 620, each controlling five out of fifty relays such as 621, each of which controls four out of two hundred relays such as 622. , The windings and armatures of the relays 620, 621, 622 are connected, after the number has been fully registered, over the springs of the corresponding thousands relay 517 to the contacts of switch arms 521, 524, 527, 529, 534 of the register. Each line marker is accessible to ten registers, each marker having ten sets of relays like 600, 6)1, 605, 611, one set for each register, and switches 604, 607, 610, which allot the use of the marker to the different registers in order and continually shift the preference. Operation of thousands selector TS, Fig. 3. When the switch arm 510 moves to its second position after the thousands digit, a circuit is closed for relay 410, Fig. 4. The relays 410, 412, 413, 416 are individual to the register, whereas the relays 411, 414, 421, 422, 424 and magnets 417, 420 controlling switches 415, 418, 419 are common to all the registers. These switches associate the thousands marking wires, leading from switch 507, with the register in turn, and continually shift the preference. Relay 410 causes relays 413, 416, 414, 422 to energize in succession if the thousands marking wires are available. Relay 422 closes a circuit over wire 423 and switch SNS for the vertical bar magnet 335 (corresponding to trunk 300) in the thousands selector TS. The magnet 335 causes relay 337 to connect up the thousands marking wires and energizes relay 421, which completes a circuit over switch arm 507 and the selected thousands wire 508 to operate the first idle cross-bar in the selected thousands group. The magnet 340 of this bar energizes over its right-hand winding and wire 508, and locks up with both windings in series with relay 339 dependent on relay 221. The vertical bar magnet 335 is subsequently disconnected, the contacts being maintained by the cross-bar magnet 340. Action of all trunks in desired group are busy. In this event, a circuit is closed over the thousands marking wire 508, front contacts of all the relays 339, 347 of the trunks in the group, wire 342 for a relay 406, which connects a busy tone generator to the calling line. Operation of line marker and preparation of talking circuit. After the transmission of the units digit, arm 510 of the distributing switch closes a circuit over its fifth contact, the armature of relay 512 (energized after the operation of the thousands selector), and arm 515 of the thousands switch for a relav 600, Fig. 6, of the line marker of the selected group. This results in the energization of the relays 601, 605, 603, 602, 609, 611, 615, and magnets 606, 612 controlling auxiliary switches 604, 607, 610, thereby associating this marker with the register in use. The relay 611 energizes the corresponding thousands magnet 517 which connects the contacts of the hundreds, tens, and units switch arms to the armatures and windings of the relays of the line marker. If, or when, the relay master switch of the primary switch associated with the wanted line is free, its relay 112 is de-energized and a circuit is closed for relay 111 over wire 127. Relay 111 energizes the vertical magnet 129 of an idle trunk 201 to which the wanted line is to be connected, and magnet 129 in turn energizes a relay 211 which energizes the vertical magnet 234 of an idle trunk 301. Magnet 234 energizes the vertical magnet 236 of the same trunk 301 in the incoming trunk selector ITS. The energization of relay 111 also results in the energization of relays 125, 211, 241, 205, 518, 614, 618. The relay 518 earths the switch arms 521, 524, 527, 534, thereby energizing a combination of relays, such as 620, 621, 622 of the line marker whereby the wanted line is selected. Busy test of wanted line and busy release. The relay 614 open-circuits relay 615, and during the release of the latter a circuit is completed, if the wanted line is busy, from earth on t