Patent GB-190930458-A (GB)
Title: Improvements in or relating to Telephone Exchange Systems.
Inventor: MARTIN TALBOT GRANT
Filed: 1909-12-30
Granted: 1911-01-30
Abstract: 30,458. Martin, T. G. Dec. 30. Automatic exchange systems.-The vertical and rotary line relays, controlling the operation of a selector, are adapted also to repeat the subsequent sets of selecting-impulses to the next selector or connector, which may be at a distant exchange, and also to serve as impedances through which a calling line is fed with microphone current. In the system shown in Figs. 1 and 2, the combined selector and repeater C functions as a first selector and is shown as having selected a two-wire trunk 113, 114, leading to a distant exchange, at which the connexion is completed by a second selector and connector D. In a modified system, the combined selector and repeater functions as a second selector. Sub-station impulse-transmitter. To prevent rotation of the dial 10 before the receiver is removed, a pivoted locking-arm 19 co-operates with a dog 19<a> fixed to the dial shaft. The rise of the switch hook raises the arm 19 and releases the dog 19<a>, and the subsequent movement of the dial raises the arm 19 further so that the spring 21 engages the earthed spring 20. First selector and repeater. If a subscriber wishes to call station No. 2345, he removes his receiver and proceeds in the usual way to send sets of two, three, four, and five impulses over his vertical lead 90, each set of impulses being followed by a single impulse over the rotary lead 91. The selecting-impulses pass from the battery B over the winding 93 of a differential relay 63, vertical relay 47, lead 90, and contacts 12, 22, 21, 20 to earth at the sub-station. The rotary impulses pass from the battery B over the contacts 104, 103 of a pole-changing relay 36, winding 106 of the relay 63, rotary relay 49, lead 91, and contacts 14, 22, 21, 20 to earth. The first set of impulses over the lead 90 are repeated by the relay 47 to operate the vertical magnet 48, the circuit of which includes the side. switch 42 and a contact of the private magnet 46. The wipers 39, 40, 41 are thus raised to the second row of contacts. The, single rotary impulse causes the relay 49 to energize the private magnet 46 which moves the side-switch arms 35, 42, 43, 44, 45 into their second position, thereby completing the circuit of the self-interrupting rotary magnet 50, and moving the switch wipers on to the first set of contacts in the selected row. There is a mechanical connexion between the armatures of the magnets 46, 50, so that if the selected trunk is idle, the armature o f the rotary magnet at once moves the side-switch into its third position. If the line is engaged, its test - contact is earthed at some other first selector, so that the private magnet 46 remains energized, and attracts its armature until the testwiper 41 finds an idle trunk, the magnet 46 then moving the sideswitch into its third position, in which the test-wiper 41 is earthed over arm 44, and the operating-springs of the re'ays 47, 49 are connected over the contacts 121, 132 of the relay 36 to the trunks 113, 114. The first vertical movement of the selector shaft closes a contact in the circuit of a lamp 60, which indicates to the exchange attendant that the selector is in an operated position. Second selector. The second set of three impulses sent over the lead 90 is repeated by the relay 47 in the trunk 113 and verticil relay 64 of the selector F, the wipers of which are raised by the vertical magnet 66 to the third horizontal row of contacts. The single impulse over the lead 91 is similarly repeated by the relay 49 to the trunk 114 and rotary relay 65, which controls the selection of an idle connector in the same manner in which the selection of an idle second selector was effected, the test-lead 144 being ultimately earthed through a release relay 69. Connector. The third set of four impulses sent by the calling subscriber is repeated by the relay 47 over the leads 113, 141 to the vertical relay 74, Fig. 2, which in turn closes the circuit of the vertical magnet 79 so as to raise the wipers 76, 77, 78 to the desired level. The subsequent single impulse is repeated by the relay 49 to the rotary relay 75, which earths the private magnet 82 over a contact 155 of a differential relay 89. The magnet 82 moves the side-switch into its second position, so that the final set of impulses is repeated in turn by the relays 47, 74 to the rotary magnet 80, which moves the wipers 76, 77, 78 to the contacts of the desired line. Busy test and busy release. The last single impulse over the lead 91 is repeated by the relays 49, 75, to the-private magnet 82, which, if the called subscriber is engaged, completes a release circuit passing from the battery B' through the springs 165, 164 of a differential relay 88 (momentarily energized by the single impulse passing through the relay 75 and winding 153), release magnet 87, contact 200-201 of the magnet 82, side-switch 85 in its second position, to the test wiper 78 and earth. The connector is thus released, and the first and second selectors are released when the calling subscriber hangs up his receiver as described later. A busy signal from the transformer I is given to the calling subscriber when the latter depresses his call button 28. Ringing-through and supply of microphone current. If the called subscriber is idle, the private magnet 82 moves the side-switch into its third position, in which the test-lead 160 is earthed over the arm 85, thereby completing the circuit of the pole-changing and cut-off relay 162 of the called subscriber. To ring-up the called station, the calling subscriber depresses his button 28, thus sending a prolonged impulse over the lead 90, which is repeated in turn by the relays 47, 74 to the ringing-relay 81, which bridges the calling- generator H across the line of the desired subscriber. When the called subscriber removes his receiver, a series energizing circuit, which also supplies microphone current to the called station, is closed through both windings of the pole-changing relay 89, which disconnects its contact 154 from the battery lead and connects it to earth over arm 85. This reversal of the polarity of the spring 154 establishes a circuit for the pole-changing relay 36 of 'the first selector, which may be traced from the battery B<1>, over the winding 146 of the relay 88, relay 74, leads 141, 113, relay 36, contact 187 of the relay 63, leads 114,142, relay 75, winding 153 of the relay 88, springs 154, 186, and arm 85 to earth. The relay 36 reverses the connexions of the relay 49 so that microphone current then flows to the calling station from the battery B through the winding 93 of the relay 63, relay 47, lead 90, sub-station apparatus, lead 91, relay 49, winding 106 of the relay 63, contacts 103, 189, and arm 45 to earth. The relays 47, 49 are thus energized during a conversation, but produce no effect as their local circuits are opened at the contacts of the relay 36. The differential relay 63 is not energized at this stage, thus keeping the circuit of the release magnet 51 open at contact 191. Release. When the calling subscriber hangs-up his receiver, the springs 32, 33, 34 engage, thus momentarily grounding both leads 90, 91. The relay 49 and winding 106 are thus deprived of current, which continues to flow through the winding 93, and relay 47 to earth at the sub-station. The relay 63 is thus energized, and opens at 186 the circuit of the pole-changing relay 36, which reverses the battery connexions so that current flows from the battery B over the windings 93, 106 and relays 47, 49 in parallel to earth at the substation. The relay 63 is energized by this current, and the simultaneous energizing of the relays 47, 49 completes the circuit of the release magnet 51 over the contact 191, magnet 51, and outer springs of the relays 47, 49. The magnet 51 is thus energized and remains in readiness to release the selector when its circuit is broken. The simultaneous excitation of the relays 47, 49, at a time when the relay 36 is not energized, earths both the trunks 113, 114, and leads 141, 142. The earthing of the trunk 113 short-circuits the relay 75 and winding 153 of the relay 88, but the winding 146 and relay 74 remain energized by current passing over the earthed trunk 114. The relay 88 is consequently energized and opens the circuit of the pole-changing relay 89, which reverses the connexions of the winding 153 and relay 75, so that current now flows in parallel over the windings 146, 153, and relays 74, 75, to earth at the selector C. The relay 88 is energized by this current, and the simultaneous energizing of the relays 74, 75 completes the circuit of the release magnet 87 from the battery B<1> over the contact 164, 165, magnet 87, outer contacts of the relays 74, 75, test-lead 144, and back release relay 69 of the second selector to earth. The magnet 87 releases the connector D and the relay 69 completes the circuit of the release magnet 68 of the selector.