GB183436A - Improvements in automatic telephone switches - Google Patents

Abstract

183,436. Western Electric Co., Ltd., (Assignees of Reynolds, J. N.). July 21, 1921, [Convention date]. Automatic exchange systems; selectors.-A cross-bar switching mechanism, suitable for connecting a calling line with an idle trunk of a group, comprises sets of horizontal wires 1, 2, 3, 4, each set corresponding to a subscriber's line, and a plurality of vertical rows each containing sets of multipled spring contacts 8, 9, 10, 11 corresponding to an outgoing trunk, means being provided for establishing connection between any set of horizontal conductors and any row of spring contacts. The spring contacts 8 - - 11 are mounted in insulating blocks 6, and at their other ends project through diagonal slots 12<1> in an insulating card 12 carried by spring members 13, 14, in such a manner that the ends of the springs 8 - - 11 pass between but normally do not touch the horizontal conductors 1 - - 4. Trunk bars 15 pivoted to the main frame carry armatures 16 which, when a magnet 17 corresponding to the next available trunk is energized, rotate spring rods 23 into position below the notches 12<2> in the cards 12. When a subscriber calls, a magnet 26 individual to his line energizes to rotate the line bar 24 so that the notched end of a rigid arm 27 engages the end of one of the displaced rods 23 corresponding to the preselected trunk to lift the card 12 and bring the springs 8 - - 11 into contact with the line conductors 1 - - 4. The diagonal slots in the cards 12 provide a lateral rubbing action for the contact springs, whilst, in addition, a longitudinal rubbing may be provided by weaving the line conductors 1 - - 4 in and out of the insulating blocks 5 as shown. The notches in the arms 27 hold the cards in position to maintain the connection, even if the trunk magnet 17 is released and again operated. Specification 183,438 is referred to.