Patent GB-196990-A (GB)
Abstract: 196,990. Baron, H., (Aldendorff, F.). Jan. 30, 1922. Automatic exchange systems.-In a group selector comprising a main switch provided with groups of bank contacts arranged in the same level and an auxiliary switch which responds to a set of impulses to mark the group over which hunting is to take place, the wipers of the main switch commence to move as soon as the impulses start coming in. During the first part of the movement, a relay energized over unmarked groupdesignating contacts disconnects the test relay. but as soon as the marked group is reached, the test relay comes into operation. The release of the main switch is also controlled by the auxiliary switch, the removal of the marking potential from the selected group causing the wipers to be stepped forward until the normal position is reached. In the system described, the connectors also comprise, main conversational switches controlled by auxiliary tens and units marking switches, the wipers of the main switch commencing to travel whilst impulses are arriving at the marking switches. In the following description it will be assumed that a calling subscriber T desires connection with subscriber No. 233. Non-numerical switching arrangements. Callfinders of the type described in Specifications 189,841, 195,439, 203,724 or 207,219 may be employed. Group selector, Fig. 1. The first set of impulses is repeated by line relay 18 over contacts 26, 23, 24 to the stepping magnet 17 of the auxiliary marking switch Gd. Contact disc 3 and wiper 4 are stepped forward and the second group-designating contact 13 is marked selectable by the removal of negative potential therefrom owing to the notch in the disc 3 being opposite contact 10. As soon as the disc 3 commences to move, it completes a circuit 50, 32 for the stepping-magnet 16 of the main switch, the wipers 5 - - 8 of which start to rotate. Whilst they are passing over the first group of contacts, relay 39 is energized over contacts 8, 12, 3 to disconnect the test relay 20', but when the second group is reached, relay 39 falls back and the test relay is connected up over the test wiper 7. When an idle trunk 110, 111, 112 is reached, the test relay energizes over lead 112 and contact 113, Fig. 2, and (1) opens the circuit of magnet 16, (2) shortcircuits its own left-hand winding to mark the selected trunk busy, (3) switches through at contacts 34, 35, (4) closes contact 36 to maintain line relay 18 energized and (5) locks up restoring relay 27. Connector, Fig. 2. The second set of impulses are repeated by line relay 118 over contacts 126, 129, 137, 139 to stepping magnet 167 of tensdesignating switch Td, the arcuate wiper 170 of which connects negative potential to contact 175 and to the first two group contacts 172, 173. Relay 165 energizes over contacts 109, 175, 170 and completes a circuit for the driving-magnet 176 of the wipers 105 - - 109 of the main switch. At the end of the tens impulses, relay 168 energizes over contacts 138, 174, 175 and the last set of impulses is repeated over contact 140 to the stepping-magnet 181 of the units-designating -switch Ud, the wiper 183 of which marks the third bank contact 186 and the associated mainswitch bank contact 187. When the wipers 105 - - 109 reach the third group of contacts, relay 165 de-energizes, but driving magnet 176 is now energized over contact 163 and wiper 185 of switch Ud. When wiper 108 reaches marked contact 187, relay 159 energizes over contacts 187, 183, 138 to open the circuit of magnet 176 and close the circuit of test relay 188. If the wanted line is idle, relay 188 energizes, completing the connection at contacts 149, 150, marking the called line busy' at contact 153, and closing a circuit 155, 184, 187 for the restoration of the switch Ud to normal. Ringing arrangements. Relay 188 also completes a circuit for the upper winding of ringing relay 148 over wiper 185, and ringing current is transmitted to the called line over contacts 147, 145. After the switch Ud has reached its normal position, the ringing relay is intermittently energized over its lower winding and interrupter. 156. When the called subscriber replies, ringing-cut-off relay 142 energizes and locks up an auxiliary restoring relay 191. Release. When the called subscriber hangs up, relay 142 falls back, and relay 120 is short-circuited over contacts 132, 134 and therefore deenergizes, unlocks relay 159, and closes a circuit 127, 125, 195, 167 for the restoration of switch Td. When the wiper 171 reaches contact 196, arcuate wiper 170 is connected to all the group contacts 172, 173, 178, &c., and relay 165 is energized to close the circuit of the driving magnet 176 which rotates the wipers 108 - - 109 to their normal position in which wiper 109 rests on contact 174 and relay 165 is de-energized. Magnet 167 is now energized over contacts 171, 196, 162 and completes the restoration of switch Td. The de-energization of relay 142 when the called subscriber hangs up also causes relav 20', Fig. 1, to fall back since contacts 113, 133 are now both open. Magnet 17 energizes over contacts 31, 29, 15, 4, 60 and restores the switch Gd to its normal position in which the wiper 4 is opposite the gap in the ring 15. The restoration of disc 3 places negative potential upon all the contacts 12, 13, 14, &c. over which relay 39 energizes and completes the circuit of magnet 16, at the same time opening the circuit of the test relay 20<1>. The wipers 5 - - 8 are thus advanced by the magnet 16 until the normal position is reached. Premature release. If the calling subscriber hangs up before the wipers 5 - - 8 have selected an idle trunk, relay 19 falls back and completes a circuit for magnet 17 over contacts 25, 15, 4 thus initiating the release of the switches as above. The Provisional Specification describes a similar system in which quick-acting and slow-acting call-finders are employed, the quick-acting finders being of the type which comprise a number of sets of wipers associated with different groups of calling lines and each set having a separate driving magnet, only those wipers which have access to the calling line being employed for any particular call.