GB722435A - Improvements in or relating to cross-bar switches of the type used in telephone systems - Google Patents

Abstract

722,435. Electric selectors. STANDARD TELEPHONES & CABLES, Ltd. Fell. 22, 1952 [April 13, 1951], No. 4730/52. Class 40 (4). An electric selector comprises a set of fixed parallel conductors carrying resilient contact extensions movable into engagement with corresponding members of another set of fixed parallel conductors perpendicular to the first set, movement of the contact extensions being effected by one of a set of fingers movable perpendicularly to both sets of conductors. The invention is applied to flat switches such as are described in Specification 662,784 and 722,438, which can be stacked to operate as a cross-bar switch. A set of parallel strip conductors 5 fixed to an insulating plate 2 carry resilient contact extensions 7 for cooperation with one or other sets of perpendicular conductors 4 and 41 fixed by passing through holes in the insulating plate. Each extension 7 engages in a narrow slot 12 in an associated finger 10, which also has wider slots 12<1> to permit free relative movement of the extension 7 associated with the adjacent finger. The fingers 10 are biased to a central position by levers 41, 41<1> spring-pressed against stops 42, 42<1>. Depression of one or a vertical set of clutch levers 24, as by a select bar in a cross-bar switch, engages the vertical set of levers 24 in corresponding notches in hold bars 20, Figs. 1 and 5. Movement of one of the bars 20 in one or other direction rocks the selected clutch lever 24 and its associated second clutch lever 26 to move the associated finger 10 longitudinally to engage the selected extensions 7 with one or other set of conductors 4 or 4<1>. The select bar can return to normal position, the connection being maintained until the hold bar is restored. The switch may be duplicated below the insulating plate 2. Control of hold bar 20. Operation of magnet 52, Fig. 6, rocks lever 54 counter-clockwise to cause nose 64 of lever 61 to depress a pair of levers 48, 49 whereby their ends 50, 51 engage over a bar 74. The bar 74 can be moved in either direction by apparatus not shown to push lever 48 or pull lever 49 so as to move the bar 20 longitudinally in one or other direction. The projection 66 or 67 on the lever 48 or 49 slips over the end of the nose 64 under the action of spring 75 or 76 to hold the bar 20 in displaced position until the magnet 52 restores.