Patent GB-833722-A (GB)
Title: Improvements in or relating to cross bar switches for automatic telephone systems
Inventor: LUNDKVIST KARL AXEL
IPC: H01H67/26
Filed: 1957-05-01
Abstract: 833,722. Automatic exchange switches. TELEFONKTIEBOLAGET L. M. ERICSSON. May 1, 1957, No. 13944/57. Class 40 (4). In a cross-bar switch of the type in which each selecting bar has associated therewith a plurality of contact spring sets, one per operating bar, and in which each set consists of two or more groups of contact springs located one above another, a driver being individually associated with each set and being so positioned by the operation of the relevant selecting magnet that on subsequent operation of the relevant operating magnet the movement of the operating bar concerned causes the driver to bring all the contact springs of the groups of that set into contact with the wires of two or more corresponding groups of transverse intermediate conductors, that group of contact springs of the set which is to be effectively included in a connection through the switch is determined by providing an auxiliary selecting bar associated with a plurality of auxiliary contact spring sets, one per operating bar, each such set being arranged in groups as are those of the main sets, an auxiliary driver for each group in each auxiliary set, and change-over means in association with each operating bar for controlling the auxiliary drivers of the auxiliary contact spring set concerned, which means is operated by the auxiliary selecting bar so that one only of the auxiliary drivers becomes capable of being engaged by the operating bar so as to effect contact between the relevant group of the auxiliary set and the corresponding group of intermediate conductors. Twenty-five or twenty-six line selector.-Figs. 1 and 2 show separately one embodiment of an auxiliary contact spring set and of a main contact spring set, respectively. Operation of the relevant selecting magnet moves selecting bar 31 (Fig. 2) downwards whereupon the driver 41, attached thereto by the spring 41a, turns anti-clockwise so that its lower end is above the operating bar 6. The auxiliary spring set has two drivers 4 and 5 (Fig. 1) associated with the spring set groups 2a, and 2b, respectively, the drivers being normally in the positions shown with the lower end 5b of driver 5 engageable with the left-hand edge of the hole 6a in the operating bar 6. Operation of the auxiliary select magnet S pulls the auxiliary selecting bar 3 downwards, whereupon the drivers turn anti-clockwise so that the lower end of driver 5 is located above the hole 6a and that of driver 4 becomes engageable with the edge of the operating bar 6. When the operating magnet is operated the operating bar moves upwards causing the driver 41 to bring the wires of spring set groups 21a and 21b (Fig. 2) into contact with those of groups a1 to dl and a2 to d2, respectively, of the transverse intermediate conductors. The raising of the operating bar also causes the auxiliary driver 5, or 4, to bring the wires of group 2b, or 2a, into contact with those of group a2 to d2, or a1 to dl, according as the auxiliary selecting magnet S is released or operated, respectively. As shown in Fig. 3 the outlets F1 and F2 of Fig. 1 are in fact multiple appearances of the line F, so that in the former case this line F is connected to line L2 (Fig. 2), and in the letter to line L1 (Fig. 2), and with the thirteen select bars indicated, twenty-five or twenty-six lines such as L1 may be accommodated by the switch. In the modification of Fig. 4 (not shown), instead of the auxiliary drivers being moved by the auxiliary selecting bar, an operating member is provided which is normally interposed between the operating bar and driver 4, but is moved by the auxiliary selecting bar to a position between the operating bar and driver 5. In a further modification (Fig. 5, not shown) operation of the auxiliary selecting magnet rotates the auxiliary selecting bar about its axis and moves a selecting finger from its normal position between the operating bar and driver 5 to one between the operating bar and driver 4. Larger switches, e.g. a 50-line switch (Figs. 6-7, not shown), may be built up by combining units such as those described above, the selecting bars 3 and 31 serving all the units. Further modifications (Figs. 8, 9, not shown) have three auxiliary drivers and a selecting finger, which is normally under the centre one, may be moved to right or left to operate one or other of the remaining two drivers by operation of one or other of two selecting magnets acting on the single selecting bar to rotate it clockwise or anti-clockwise.