Patent GB-544954-A (GB)
Title: Automatic telephone system
IPC: H01H67/26
Filed: 1940-11-08
Abstract: 544,954. Automatic exchange systems. LEICH ELECTRIC CO. Nov. 8, 1940, No. 16274. Convention date, Nov. 30, 1939. [Class 40 (iv)] In a unitary switch-mechanism of cross-bar type suitable for use as a finder, group selector or connector, 300 conductors representative of 100 lines are arranged in 30 superposed horizontal layers and extend the whole length of a box-like structure which is divided into a number of sections, e.g. 10, each individual to an incoming or outgoing trunk, connections between any line and any trunk being made through the medium of 30 contact strips in each section extending across the 300 conductors. Fig. 10 shows three of the contact strips 16, 28, 40 of one section, each carrying 10 spring contacts 18, 19, 20 ..., one for each of the conductors 24, 25, 26 ... it crosses, and an additional contact 17 for engagement with. a contact 22 individual to the layer, the contacts 22, 30, 42 in each three layers being connected in multiple to the individual trunk of the section. For the operation of all the contacts in any one of the 10 vertical rows, each section is provided with 10 vertical rods 61, Figs. 2, 9, each having projections 62, 63, 64 ... located beneath the contacts such as 18, 36, 55 ... and terminating at the upper end in a hook 65. A comb-like lateral member 96 has 10 spring fingers 97 with stepped ends 98 any one of which may be brought below a 'corresponding hook 65 by means of a projection 121 on a longitudinallymovable bar 111, there being 10 such bars common to all the sections and controlled by the armatures of 10 tens magnets mounted on the upper frame plate 3. The member 96 is carried by a gate comprising vertical arms 91, 92 which are supported on the armature 100 of a magnet 75, so that energization thereof raises the member 96 and the vertical rod 61 selected by the movement of a bar 111. For the operation of any set of three contacts such as 17, 35, 48 to complete the connection to the trunk, 10 blocks 160 are provided each having projections located beneath the three contacts, and the arm 91 of the gate carries 10 spring fingers 163 with bent ends 164 any one of which may be brought into position to engage a slot in the corresponding block by means of a projection 183 on a longitudinally-movable bar 181, there being 10 such bars common to all the sections and controlled by the armatures of 10 units magnets mounted on the side plate of the structure. In addition to the sections so far considered, there is a special section, Fig. 1 (not shown), for making connections to the test conductors, a cross-strip being provided for every third layer and the spring contacts in a vertical row being operated by a vertical rod which is lifted by the movement of the tens bar 111. The cross-strips are permanently connected to individual leads, which may go to the units magnets. The connections effected by the selected rod 61 and block 160 are maintained by the gate magnet 75, the tens and units bars 111, 181 being released as soon as the magnet has operated. The switch unit provides for as many simultaneous connections as there are sections, but obviously only one connection can be established at a time. Exchange system.-A 1000-line exchange requires 30 switch units, 10 serving as finders, 10 as group selectors and 10 as connectors, the selectors and connectors being controlled by common markers. The finders and connectors are each individual to a group of 100 subscribers' lines, four of the line circuits being shown. When a call is made, line relay 306 connects up the appropriate tens magnet 332 of the finder, Fig. 11, and applies battery through cut-off relay 307 to the test wire which is extended in the special section of the switch (the rod 320 being lifted by the tens bar) to connect up the appropriate units magnet 341. The tens and units magnets are arranged so that only one in each set can be operative at a time. The units magnet 341 makes a circuit for guard relays 381, 382 ... of all the outgoing trunks that are idle, the test wires thereof being connected to battery, and the first of these relays, e.g. 381, pulls up and disconnects the rest, and in addition energizes the corresponding gate magnet 371. The magnets 332, 341 and guard relay 381 are now disconnected by means of relay 337, and the connection of the calling line to the trunk 365-367 established by the vertical rod 322 and block 325 is held by the gate magnet. Rectifiers in series with the units magnets and guard relays prevent the possible operation of two magnets or relays in series by battery on one test wire and ground on another. At the group selector, Fig. 12, the incoming trunks pass over normal contacts of the corresponding gate magnets 471, 472 ... to a marker. Upon seizure of the trunk 365-367, line and release relays 400, 401 energize, the test wire being grounded to operate cut-off relay 307 in series with line relay 306 and to hold the gate magnet 381 of the finder. Dialled impulses are registered by a chain of 5 counting relays 405-409 with a transfer relay 410, and these control the tens magnets 431, 432 ... over marking wires.. On the relapse of a dialling relay 403 at the end of the digit, relay 404 energizes and connects up a sequence relay 411 to complete the circuit for the appropriate tens magnet. There may be two or three markers for each selector, and their sequence relays 411, 412 are arranged so that only one can be operated at a time. Test circuits are made in the special section of the switch for the units-magnets 441, 442 ...and the one associated with the first idle trunk pulls up. Relay 470 now operates and inserts the gate magnet 472 in the incoming test wire, so that it energizes and extends the connection to the selected outgoing trunk, the marker being released. At the connector, Fig. 13, the incoming trunks such as 460-462 pass over normal contacts of the gate magnets 571, 572 ... to a marker, Fig. 14. The latter has two sets of counting relays 612-617, 608-603, similar to 405-410, Fig. 12, for registering two dialled digits, transfer being effected by relay 611 which pulls up on the relapse of dialling relay 610 after the first of the two digits. Relay 609 pulls up after the final digit and connects up a sequence relay 621, like 411, Fig. 12, which completes the marking circuits to the appropriate tens and units magnets 531, 532 ..., 541, 542 . . . A test circuit is made in the special section of the switch for relay 618, which if the selected line is idle pulls up in series with its line and cut-off relays. Relay 570 operates and inserts the gate magnet 571 in the incoming test wire, so that it energizes and extends the connection through a feed bridge to the line, the marker being released. Line and release relays 520, 521 energize, grounding the incoming test wire, and ringing takes place in the usual manner. The testing operation occurs during the release period of relay 619, which, if relay 618 is inoperative owing to a busy condition, on falling back opens the marking circuits and applies a busy signal. The markers at the group selector and connector stages are controlled by timing apparatus which serves to bring about release of the partial connection in the event of a permanent'loop condition by removing ground from the test wire. The looped line then becomes locked to the cut-off relay.