Patent GB-145066-A (GB)
Abstract: 145,066. Western Electric Co., (Assignees of Gherardi, B.). Aug. 31, 1915, [Convention date]. Exchange systems.-In junction and trunk line working between exchanges, the supervisory signals, and in some cases ringing control currents, are transmitted over an auxiliary line which is associated with all the inter-exchange trunks in succession by means of synchronous distributors at the two exchanges. This arrangement facilitates phantom-circuit working and the use of the telephone trunks for telegraphy. The auxiliary line is duplexed for conveying signals in both directions. First system, Fig. 1. The duplex auxiliary line 3 is connected to synchronous distributors 7, 7<1> comprising transmitting sunflowers 8, 8<1> and receiving sunflowers 9, 9'. When the operator X inserts plug 14 in jack 15 of junction line 1, relays 18, 25 are energized and negative battery is connected to segment 11, energizing polarized relay 6' which closes a, circuit through segment 13' to energize relay 21<1> at incoming end of junction line 1, and call lamp 23<1> lights up. Relay 6<1> is energized only once every revolution of the distributor, but relay 21<1> is sufficiently sluggish to hold up its armature during the inteawals. When the operator Y responds by inserting plug 14<1> in jack 15<1>, relays 18<1>, 25<1> are energized, extinguishing lamp 23' and connecting negative battery to segment 11<1>, so that relays 6, 21 are energized. Relay 21 cuts an additional winding 31 of relay 18 in series with lamp 17, which has hitherto been glowing but is now dimmed by the extra resistance. When the operator X removes plug 14, relay 18 relapses and de-energizes relav 21<1>, which short-circuits winding 31<1> of relay 18<1>, reducing the resistance in the circuit of lamp 17<1> so that it glows and gives a signal to the operator Y to disconnect the plug 14'. Second system, Figs. 2 and 3. This is an order-wire system, in which the A-operator controls the ringing of the wanted subscriber at the B-exchange. The ringing-control currents as well as the supervisory signals are transmitted over the duplex auxiliary line 61, each trunk line, such as 41, having two segments 65, 95 in the transmitting sunflower and corresponding segments 65<1>, 95<1> in the receiving sunflower for these two purposes. When the operator W inserts plug 42 in jack 44 of trunk 41, which has been assigned by the operator Z over an order wire, a circuit is closed through relays 46, 47, 48 and relay 48 grounds the segment 65. Relay 58 is thus energized, once every revolution of the distributor, and energizes polarized relay 62<1>, which closes a circuit through segment 65<1> to energize relay 66', which locks itself and energizes relay 72 to light lamp 77. The operator Z inserts plug 78 in jack 79 of the wanted line, energizing relays 76, 88, 80, and relay 88 controls relays 58', 62 to energize relay 66, which locks itself up and closes a shunt 92 round relay 48, so that marginal relay 47, which has not hitherto responded, attracts its armature and lights lamp 53. The operator W now throws her ringing-key 93 to energize relay 94, which grounds segment 95, causing the energization over segment 95' of relay 97, which locks itself up and energizes relay 102, which connects ringing- current to the wanted line. When the operator W releases her ringing-key, relay 62<1> is no longer energized at the moments when the distributor arm is on segment 95', and relay 97 is shortcircuited over the upper contact of relay 62' and is unlocked, causing the de-energization of the ringing-relay 102. In the first non-ringing interval after the called subscriber answers, relay 91 is energized and opens the circuit to segment 53', causing the unlocking of relay 66 and the deenergization of relay 47 and lamp 53. After conversation, when the called subscriber hangs up his receiver, relay 91 relapses and again completes the circuit to segment 53<1>, causing the energization of relays 66, 47 and lamp 53, as before. The operator W disconnects the plug 42, de-energizing relay 48, which disconnects ground from segment 65 so as to de-energize relay 66<1>, which deenergizes relay 72, which energizes lamp 77 to instruct the operator Z to remove the plug 78.