Patent GB-184249-A (GB)
Abstract: 184,249. Western Electric Co., Ltd., and Polinkowsky, L. May 3, 1921. Automatic exchange systems.-A group selector when operated by a digit signifying a local call, extends the controlling circuit metallically to the next local selector, but when operated by a digit signifying a distant call it selects a trunk to the distant exchange and acts as a repeater for subsequent digits. In the levels devoted to local calls the first terminal in the path of the test brush is not multipled in the usual manner, but is wired back to a circuit in the selector, to determine the energization of certain relays and the movement of the sequence switch to a special position. The invention is illustrated in its application to a system of the reverting-impulse type. In the drawings, a permanent connection with a sequence switch contact spring is indicated by a comparatively large triangle. Local connection. The line relay 107 energizes relay 106 in a circuit 118, 123 and relay 117 in a circuit 118, 121, 122 energizes the sequence switch in a circuit 125, 127, 118 to drive it to its 2nd position energizing the magnet 129 to rotate the trip spindle, the rotation of which intermittently grounds the fundamental circuit at the spring 139. The opening of the fundamental circuit by the register controller, after the proper number of steps have been taken, de-energizes the relay 107 which drives the switch 108 to its 3rd position, energizing the power magnet 152, and the set of brushes selected by the trip spindle is tripped and carried over the terminals of local selectors. Since the call is over a local level, the first contact 156 engaged by the test brush 135 is wired to the contact 121 so that the relay 117 is now energized in a circuit 158, 157, 135, 156, 121, 117, 122 and locks itself. The test relav 158 is included in the same circuit but does not receive sufficient current to become energized. When an idle trunk is reached the test relay 158 de-energizes relay 107, stops the selectors and moves the switch 108 to its 5th position. Since the relay 117 has been locked up, the relay 102 is energized, as the switch runs through its 4th position, in a circuit 159, 121, 120, 165, 102, and locks itself in series with relay 103. The relay 102 disconnects the relav 107 from the fundamental circuit 100, 101 and extends this circuit metallically to the brushes 133, 134 while the relay 103 closes a circuit 118, 175, 174 to drive the switch 108 to its 13th position. In this position the numerical operations of the succeeding selectors are controlled, and when these operations are completed the resistance in the test circuit 135 is increased. by means not shown, to unlock the relay 158. which closes a circuit 150, 149, 145 to drive the switch 108 to its 14th position. The relay 117 is now bridged across the calling line in a circuit 177, 111 (the relay 102 having meanwhile de-energized) so that if this line is closed the relay 117 becomes energized and energizes relav 107 to drive the switch 108 to its 16th or talking position. If the calling line is not closed, the relay 106 is energized first by an interrupter 182 and then after an interval by interrupter 183 and closes circuits for driving the switch 108 to its 16th position. Release. When the calling connection is severed, the bridge relay 117 relapses and deenergizes relay 107 to move the switch 108 to its 17th position, and the selector is restored in the usual manner. Distant connection. When the selector A operates on a level serving a distant exchange, the relay 117 is not energized at the commencement of the hunting movement, and the relays 102 and 103 are not locked up. Consequently the fundamental circuit 100, 101 is not extended metallically to the wipers. 133, 134 and the switch 108 is not driven at once to its 13th position. When an idle trunk 200, 201 is reached the test relay 158 de-energizes the relay 107 which drives the switch 108 to its 5th position. The relay 107 is now energized over the incoming fundamental circuit, driving 'the switch 108 to its 7th position and bridging the relay 106 across the outgoing fundamental circuit through contacts 178, 120, 106, 123, 180, 170. The relay 106 is energized in series with the line relay 202 of the selector B, which energizes relays 208, 210 in a circuit 213, 211, 210, 209, 208, 207. The relay 210 moves the sequence switch 204 to its 2nd position, energizing the magnet 217 to rotate the trip spindle. The intermittent grounding of the fundamental circuit 200, 201 by the spring 226 short-circuits the relay 106, which grounds the fundamental circuit 100, 101 through contacts 132, 130, 127, 147, 109, 140. When the circuit 100, 101 is opened at the register-controller, the de-energization of the relay 107 opens the bridge across the outgoing circuit 200, 201, de-energizing relay 202 to stop the trip spindle and to drive the switch 2)4 to its 3rd position, in which the relay 202 is energized in a local circuit controlled by the test relay 210. The selector B then hunts for an idle trunk in the usual manner.