Patent GB-163288-A (GB)
Abstract: 163,288. Adams, A. H. May 13, 1920, [Convention date]. Automatic and semi-automatic exchange systems.-By means of a special switching scheme, a call is forwarded over trunks of which the numerical designation may differ, within certain limits, from that of the wanted subscriber, any numerical deviation introduced at one selector being automatically compensated at the next selector. For example, in an exchange of 10,000 lines, in which connections are set up through first, second and final selectors, suppose that a call is to be extended to subscriber No. 4692; the general sequence of operations would be as follows. The thousands and hundreds impulses operate the first selector, the terminals of which are connected to trunks numbered as shown in Fig. 4. The thousands impulses rotate the wipers into alignment with the column of terminals 41XX, 42XX - - 49XX, 40XX and the hundreds impulses raise them into contact with the terminals 46XX. If this trunk is idle the first selector seizes it, extending the connection to a second selector of which the terminals are connected to trunks numbered as shown in Fig. 5<a>. The wipers of this selector are immediately rotated one step, into alignment with the column of terminals 461X, 462X - - 469X, 460X, and the tens@pulses raise the wipers to the terminals 469X. But if the trunk 46XX is busy, the first selector continues its vertical movement to find an idle trunk, testing first the terminals 47XX, 48XX, 49XX, 40XX and then the terminals 51XX, 52XX &c. in the next column. This hunting movement may proceed as far as terminal 56XX, that is to say if the trunk having the proper numerical designation is not available the selector may seize any idle trunk of the next ten. If the first idle trunk is 55XX this trunk will be seized, extending the connection to a second selector of which the terminals are connected to trunks numbered as shown in Fig. 5. The number of steps taken by the first selector during this hunting movement is counted on a register, and the second selector is first rotated a single step, bringing i wipers into alignment with the column of terminals 551X, 552X, &c., and then an additional number of steps equal to the number recordel on the register. In the present instance nine additional steps are taken, bringing the wipers into alignment with the column of terminals 461X, 462X, &c., which are multipled to the same trunks as the terminals in the first column of Fig. 5<a>. Thus the numerical deviation introduced at the first selector has been compensated by this preliminary operation of the second selector. The tens impulses now raise the second selector to the terminals 469X. If this trunk is idle it is seized, extending the call to a final selector having its terminals numbered as shown in Fig. 6a. This selector automatically takes a single rotary step, bringing its wipers into alignment with the column 4691, 4692, &c., and is then raised by the units impulses into engagement with the terminals of the wanted line 4692. If, however, the trunk 469X is busy, the second selector continues its vertical movement to find the first idle trunk of the next ten, testing first the terminals 460X and then the terminals 451X, 452X, &c. in the next column. If the first idle trunk is 453X, this trunk will be seized, extending the connection to a final selector having its terminals numbered as shown in Fig. 6. This selector automatically takes a single rotary step, bringing its wipers into alignment with the column 4531, 4532, &c., and then four extra steps (corresponding to the four steps taken by the second selector in its hunting movement) to bring the wipers into alignment with the column 4691, 4692, &c. The units impulses then raise the selector to the terminals of the wanted line 4692. It will be seen that in this system the different second selectors and the different final selectors have their terminals differently arranged, the terminals of the several selectors overlapping oneanother column by column. This overlapping has the result of making the selectors more widely available than in the usual type of system, the peak loads of adjacent sections of the exchange being more or less merged, so that fewer selectors need be provided. The terminals of all the first selectors are similarly numbered, but terminals designated by the same number are not all multipled to the same second selector; for if there are n hundred second selectors in the exchange these will be divisible into 100 kinds, according to the numbering of their terminals; thus there will be n second selectors 46XX having their terminals numbered as shown in Fig. 5<a>, and the terminals 46XX of the first selectors will be divided into n groups multipled respectively to these n second selectors. Several methods of multiple connection between the first and second selectors are described in the Specification. Construction of selectors. As explained above, it may be necessary for a first or second selector, after reaching the top terminals of one column, to continue its hunting-movement along the terminals of the next column. This may be provided for by arranging that a single set of wipers,. after reaching a. top set of terminals, takes a rotary step and then descends in the next column, but in the system illustrated in Figs. 1, 2 and 3, each first and second selector is provided with twin sets of wipers, the lower set being spaced ten units below and one unit to the right of the upper set, and the selector being constructed so as to be able to take 20 vertical steps. At the eleventh step the upper set of wipers passes off the top terminals of a column and the lower set engages the bottom terminals of the next column. As a consequence of this arrangement, the first and second selectors are provided with an additional (eleventh) column of terminals. The selectors are of the type in which the rotary movement precedes the vertical. The stepping-action both of the selectors and of the auxiliary pilot switches takes place on the de-energization of the operating-magnets. First selector, Fig. 1. When connection has been made to an idle selector bv non-numerical switching relays 104, 103, relay 112 and a slowrelease relay 105 are energized over the calling line and relay 111 is energized in series with cutoff relay 102. Relays 111, 112 energize a changeover relay 113, which is slow to energize, and the magnet, 130 of the pilot switch 131, 132, 133. Relay 112 responds to the line-interruptions constituting the thousands impulses. At the first interruption, magnet 130 becomes de-energized and moves the pilot switch to its 2nd position, placing the rotary magnet 141 under control of relay 112. At the termination of the impulses, relay 113. which was de-energized at the first impulse and remained de-energized as long as impulses continued, becomes energized again and closes a circuit through magnet 130 and contacts 132 (2). Magnet 130 breaks its own circuit, moves the pilot switch to its 3rd position, and becomes energized again over contacts of relays 111, 112. At the first hundreds impulse, magnet 130 is again de-energized and moves the pilot switch to its 4th position, placing the vertical magnet 142 under control of relay 112, and energizing relays 114. 115. At the termination of the impulses relay 113, which was de-energized at the first impulse, again becomes energized and closes a self-interrupting circuit for magnet 130 (through a contact of relay 114) to move the pilot switch to its 5th position, in which relays 114,. 115 are de-energized again. In the interval between the de-energization of relay 114 and of the slow-release relay 115, relay 116 is connected to the test-wipers 146, 146<a>, and if the trunk on which the selector has been set is busy, relay 116 becomes energized, locks itself to the test-wipers, and energizes the vertical magnet 142 over contacts 154, 132 (5). Magnet 142 energizes the register stepping-magnet 150 and thereby breaks its own circuit at contact 154, and is energized again by the consequent relapse of magnet 150, and so on, the selector thus continuing its vertical movement while the register 152 records the number oi steps taken. As soon as the ungrounded test-terminal of an idle trunk is reached, relay 116 becomes unlocked, stopping the selector and register, grounding the test wipers, and closes a self-interrupting circuit for magnet 130 to move the pilot switch to its 6th position. Second selector, Fig. 2. Relay 207, Fig. 2, energized in the test circuit, closes a circuit from normal contact 214 through the rotary magnet 241, which breaks its own circuit by energizing relay 208. The rotary step thus effected disconnects the original circuit of the rotary magnet through the normal contact 214, but the magnet 241 immediately becomes energized again in series with the register restoring magnet 151 in a circuit through the register switch 152 and the fourth wiper of the first selector. Under control of relay 208, this circuit is intermittently opened, with the result that the second selector is rotated and the register 152 stepped back towards normal. These movements cease when the register regains its normal position, since the above circuit is then open. A slow-release relay 209, which was energized as long as the armature of relay 208 was vibrating, now relapses, and magnet 230, which was energized by relay 209, moves the pilot switch 231, 232, 233 to its 2nd position, in which magnet 230 is energized again over contacts 231 (2), the a speaking wire, and contacts 131 (6). At the first impulse of the tens series relay 112 opens this circuit to move the switch 231, &c. to its 3rd position, energizing relay 211 and placing the vertical magnet 242 under control of line relay 112, Fig. 1, in a circuit through the a speaking wire. Magnet 242 energizes relay 210, which energizes slow-release relay 213, which energize