Patent GB-150300-A (GB)
Title: Telephone exchange systems
IPC: H04Q3/42
Filed: 1920-06-04
Abstract: 150,300. Western Electric Co., (Assignees of Lundell, A. E.). Aug. 23, 1919, [Convention date]. Automatic and semi-automatic exchange systems.-In systems in which the number of the wanted line is recorded on registers which control the establishment of the connexion, the registering-mechanism comprises means for readily altering the numerical basis on which connexions are made to certain lines or groups of lines. In the semi-automatic system illustrated, these alterations are effected by changing the wiring of an inter-connecting board 443, Fig. 4, to vary the connexions of the terminals of a register switch 417 with the wires leading to the different relays of the counting-chain shown at the bottom of Fig. 3. The switch 417 sets itself to a position corresponding to the two-digit number recorded on the keys 401, 402. During the operations of the group selector 112, Fig. 1, and final selector 201, Fig. 2, the building-up of the relay counting-chain begins from points in the chain determined by the setting of the switch 417 and by the wiring of the board 443, impulses being delivered from the stepping-relay 315 to the counting-chain through a wiper 424 when the selector 112 is in operation and through a wiper 428 when the selector 201 is in operation. The extent of movement of the selector 112 for a given called number can therefore be altered at will by changing the connexion of a jumper-wire such as 427, to which connexion has been made by the wiper 424, and the extent of movement of the selector 201, Fig. 2, (which is. supposed, for the sake of simplicity, to be a single-coordinate switch) can be altered by changing the connexion of a jumper-wire such as 431, to which connexion has been made by the wiper 428. Operation of the register switch 417. When the operator plugs into a calling line, a sleeve relay 103 drives the switch 105 to its 2nd position, closing a circuit 108 to energize relay 302, which locks itself in a circuit 306 and drives the switch 301 to its 2nd position. The operator records the wanted number on keys 401, 402 and presses a starting-key 405, energizing relay 406, which locks itself through the commutator brush 410 and drives the switch 301 to its 3rd position, energizing the up-drive magnet 408 of the switch 417, which lifts its wipers over the terminal bank. The relay 406 is kept energized by circuits through the wipers 414, 415 and contacts of undepressed keys 401, 402, but when the wipers reach the terminals corresponding to the wanted number (the 26th set of terminals, for example, if the 2nd and 6th keys have been depressed) there is no such circuit to keep the relay 406 energized, and as soon as the wipers are centrally positioned on the terminals, i.e. when the brush 410 comes on to an insulated commutator segment, the relay 406 relapses, open-circuiting the magnet 408 and driving the switch 301 to its 4th position. Operation of the group selector 112. A fundamental circuit 115, 316 is now closed through the stepping-relay 315 and relay 113. The relay 113 lecks itself through contact 119 and drives the switch 105 to its 3rd position, energizing the updrive-magnet 120. As the selector rises, the fundamental circuit is intermittently grounded through the commutator brush 128, short-circuiting relay 315, which transmits impulses through the wiper 424 to the relay counting-chain. Assuming that the register switch 417 was set to make connexion with the jumper-wire 427, the first energization of relay 315 will have energized relay 9, which closes a circuit for relay 9', which is, however, for the time being, short-circuited by relay 315. The first de-energization of relay 315 removes this short-circuit, allowing relay 9<1> to become energized, and subsequent energizations and de-energizations of relay 315 cause, in known manner, the successive energization of relays 8, 8', 7, 7', &c., until finally the relay 0' is ener-. gized, which opens the fundamental circuit, unlocking relay 113, which stops the selector and drives the switch 105 to its 6th position. Relay 0' also drives the switch 301 to its 6th position. during which movement the relays of the counting-chain are unlocked at contact 320. The relay 138 is now energized and locks itself to the test-wiper 126, at the same time driving the switch 105 to its 7th position, in which the up-drive magnet 120 is again energized. When the selector 112 reaches the ungrounded test-terminal of an idle trunk of the selected group, relay 138 is unlocked, stopping the selector and driving the switch 105 to its 11th position. Operation of the final selector 201. The fundamental circuit is now extended over contacts 150, 151 to the final selector, energizing relay 207, which, drives the switch 205 to its 2nd position, from which it is again driven to its 3rd position by relay 206, which locks itself to the test-circuit 204. The up-drive magnet 215 is now energized and the movement of the selector proceeds under control of the relay counting-chain in a similar manner to that described in the previous paragraph. The contact of the stepping-relay 315 is now connected through the wiper 428 and jumperwire 431, to the relay 3, so that the relays lock up in the order 3, 3<1>, 2, 2<1>, &c. After the fourth impulse, the relay 0<1> is energized, opening the fundamental circuit and driving the switch 301 to its 16th position, in which a circuit 336 is closed to drive the switch 105 to its 16th position. The de-energization of relay 207 drives the switch 205 to its 13th position, in which testing and ring- ing operations take place in known manner, and on the response of the called subscriber the switch 205 is moved to its 16th position by relay 235. Restoration of the switch 417. When the switch 105 left its 11th position, the relay 302 was unlocked and drove the switch 301 to its 18th position, energizing the down-drive magnet 435. When the switch 417 regains its normal position, a circuit 437, 337 is closed to drive the switch 301 to its normal 1st position. Release. Signals 160, 161 inform the operator when the subscribers have disconnected themselves, and she removes the plug 101. The deenergization of relay 103 drives the switch 105 to its 18th position, energizing the down-drive magnet 163, and the opening of contact 153 unlocks relay 206, which drives the switch 205 to its 18th position, energizing the down-drive magnet 243. When the selectors regain their normal positions, the switches 105, 205 are restored to normal by circuits through the contacts 167, 244. During the restoration of the selector 201, a busy guard is kept on the test wire 204 by the contact 240.