Patent GB-191418239-A (GB)
Title: Improvements in and relating to Telephone Installations.
Filed: 1914-08-01
Granted: 1915-10-01
Abstract: 18,239. Siemens & Halske Akt.-Ges. Aug. 4, 1913, [Convention date]. Automatic exchange systems. - The subscriber's stations and the group and line selectors are each provided with a pendulum arm, and during each stage of the building-up of the connexion the subscriber's pendulum and the pendulum of a selector, are released simultaneously, and during their synchronous movements close a circuit through a depressed key at the calling station and a selecting-relay at the selector. In the case of a group selector, the selected relay connects the calling line to a switch which finds an idle line selector, and in the case of a line selector the relay controls the movement of a hunting switch which moves until it finds the terminal of the line to which the relay is connected. Subscriber's apparatus. The subscriber is provided with a series of ten keys 40 each adapted to move a rod 43 and to close a contact 41. The rod 43 opens the contact 44 and momentarily closes the contact 45. Group selector. When a subscriber takes down his receiver, the preliminary selector VW connects his line to a group selector GW1. In the case, for example, in which subscriber 435 is being called the closure of the contact 45 by the key 40 completes a circuit through the magnet 8 at the subscriber's station and the magnet 47 at the selector. These magnets release the pendulums 2, 2<1> and during the synchronous movement of the pendulums a circuit is closed over the selected contact 41, segment 13, pendulum 2, lead a, contact 48, pendulum 2<1>, segment 23, and relay 53. When the pendulums reach the end of their swing, they close the contacts 6, 6<1>, thus causing the solenoids 5, 5<1> to give them a returning impulse. The relay 53 completes a hold-on circuit for itself over the contact 61 and prepares the connexion of the calling line over the contacts 49, 60 to the brushes of a selector VW11. The relay 63, which is included in the holding circuit of the relay 53, closes contacts 64, 65 thus bringing the driving magnet D of the selector VW11 into circuit. When the arm c, reaches the terminal of an idle line selector LW, a circuit is closed over contact 64, resistance w, test relay P, contact 67, and relay C. The relay P opens the circuit of the driving magnet D at the contact 66, connects its own circuit to the relay T, and, by closing the contact 69 before the contact 62 is opened, retains a circuit for the relay 53. The relay T causes the line to test busy, and, by closing contacts 72, 73, cuts off the pendulum of the group selector GW1 and connects the line to the pendulum of the line selector LW. Line selector. The depression of the third key by the subscriber starts the pendulums 2, 2<11> by a circuit extending over the magnets 8, 8' and when the segment 12 is reached, the selecting- circuit is completed, as in the case of the group selector, over this segment, the segment 32 at the line selector LW, and the relay 82. This relay completes a holding circuit for itself over the contact 90, and connects potential to the test terminal 92 over the contact 91. The line selector is provided with the usual arms a2, b2, c2, and with a fourth arm d2, which is employed in hunting over the terminals 92, 100 for the terminal of the selected relay 82. The relay AR, which is in the circuit of the relay 82, closes the contact 77, thus bringing into circuit the lifting-magnet H1. The selector arms are raised until the arm d2 reaches the contact 92, whereupon a circuit is completed over the contact 93. relav Pa, arm d2, contact 92, 91, and relay Ta. The relay Pa opens the circuit of the lifting-magnet H, at the contact 78, and closes the circuit of the relay U at the contact 94. The relay U locks itself up over the contact 96, and opens the circuit of the relay Pa at the contact 93. The relay Ta, by opening the contact 75, de-energizes the relay 82 and consequently opens its own circuit. The circuits are now ready to receive current for the third digit, and when the subscriber depresses the fifth key, the pendulums start swing- ing as before, and the relay 84 is energized. As the relay U has closed the contact 97. the relay AR brings the rotary magnet D1 into circuit, and the arm d2 is moved round until the terminal connected to the relay 122 is reached, whereupon the relays Ta, Pa are energized as before, and the selector is held on the terminals of the wanted line. The relay Pa closes the contact 101 to complete a testing circuit over the relay P<1>, arm c2, and off-normal contact 102 of the pre-selector. The relay P<1> makes a holding circuit for itself over the contact 103 and the off-normal contact 104 of the line selector. Ringing current. The relay P' connects the relay L into circuit over the contact 107, thus connecting the ringing generator to the line. When the called subscriber replies, the bridge Spa cuts off the ringing current at the contact 108. Release. When the bridge Spr is energized, the relay S is energized over the contact 112. This relay closes its holding circuit over the contact 113, and, by closing contact 114, arranges that, when the bridge Spr releases the contact 115, the release magnet M is energized. This magnet opens the contact 67 in the holding circuit of the group selector. The relay P releases more quickly than the relay T, thus completing a circuit for the release magnet M' over the contacts 117, 118. In the case in which the calling subscriber abandons the call before the bridge Spr is energized, the time relay C operates after an interval of, say, 25 seconds, to close the contacts 119, 120, thus energizing the release magnet M. Similarly, the relay Ue may release the pre-selector.