Patent GB-248819-A (GB)
Title: Switch for automatic telephone system
IPC: H01H67/12
Filed: 1924-09-20
Abstract: 248,819. Rushen, P. C., (Lorenz Akt.-Ges., C.). Sept 20, 1924. Automatic exchange systems and selectors. - In a panel switch of the clutch-driven kind, two controlling step-by-step switches are mounted upon the main switch framework, one responding to one impulse series to select a particular brushset, and the other responding to another impulse series to lift a toothed bar to a predetermined level, after which a clutch magnet is energized and the brush carriage driven up to a corresponding level. Two modifications are described. In both the brush sets have access to 20-line groups, but in one modification the switch is adapted to respond to impulses sent on a base of twenty, whereas in the other the switch is adapted to respond to impulses sent on a decimal base. Construction of selectors. Five brush sets K1 - - K5, Fig. 1, each adapted to wipe over twenty lines in the panel bank, are mounted on a vertical bar S which slides in flanges R1, R3 of the framework R2. On the lower portion of the framework R2 is mounted a step-by-step wiper-choosing switch K6 and a release magnet M. On the bottom of the bar S an armature a is suspended by a short spring b. The armature a is located opposite a pair of discs h1, h2, Fig. 2, fixed upon the driving shaft A and adjacent to the pole pieces PI, P2 of a clutching magnet H. When this magnet H is energized, the discs h1, h2 are magnetized, attract the armature a, and thereby lift the bar S. The first digit, which consists of one to five impulses, actuates the stepping-magnet D to cause the wiper-choosing switch K6 to select ,a brush-set. The second digit consisting of one to twenty impulses actuates another stepping magnet E, the armature of which operates a pawl f<2> to lift a toothed rack T to a position corresponding to these impulses. Directly the rack T moves out of its normal position, a pair of contacts g carried by the bar S are permitted to close, and on the relapse of the usual slow release relay at the end of the second digit a circuit is closed over contacts g for the clutch magnet H. The wiper bar S is now lifted until the selected brush set K1 - - K5 engages the wanted line, in which position the contacts g in the clutching circuit are opened when they engage the bottom of the rack T. When the release magnet M is energized, a holding pawl z1 is released from a rack z on the bottom of the bar S, which drops to its normal position. A rod c connected with the armature of the magnet M' also releases the holding pawl z2 of the wiperchoosing switch K6 which is restored by a spring Sp. On the bar S reaching its normal position, a pivoted detent y mounted on its upper end engages and releases a holding pawl x for the rack T mounted on the switch framework. In the modification shown in Fig. 7, the switch is arranged to be operated by impulses sent on a decimal base. When the first digit is even and indicates that the wanted line is in the second half of a twenty-line group the bar s is lifted the distance of ten lines before responding to the second digit. For this purpose the contacts engaged by an additional wiper d4 of the wiperchoosing switch are alternately connected over wires l2, l3 to two arms g1, g2 mounted on the bar S, which also carries a third arm f connected to the clutch magnet H; the arm g1 normally engages an insulated segment i on the rack T. If the first digit is even, upon its cessation, a circuit is closed over wiper d4, wire l3, arms g2, f for the clutch magnet H. The bar S is then lifted until the arm g<2> engages the insulated segment i, and as the arms g1, g2 are arranged the distance of the lines apart, the bar S is initially lifted ten lines. The second impulse series energizes the stepping magnet E, which steps up the rack T as in the previous arrangement. On the cessation of these impulses, a circuit is closed for the clutch magnet H, if the first digit is even over the arms g2, f, and if odd over the arms g1, f, the circuit being opened when the arm g2 or g1 engages the insulated segment i. Terminal banks. The terminals consist ot tongues on multipling strips ea1, eb1, ec1, Fig. 13, running horizontally across the panel. Both sides of the panel may be used, the line finders wiping over one side and the connectors over the other. The three terminals ea, eb, ec, of a line are arranged side by side in staggered relationship. The terminal tongues are bent in any of the three ways shown in Fig. 11 to form a vertical surface. If the edges are bent to form an inverted U, the brushes preferably consist of pairs of arms ea2, Figs. 12 and 13, with punchedout inclined tongues q at their ends, so that when moving upwards the upper surfaces of the tongues q act against the downwardly-projecting edges of the terminals, while when moving downwards the edges of the tongues q move over the curved upper surfaces of the terminals. Distance strips ef are inserted between the pairs of brushes ea2 to prevent the brushes engaging two contacts simultaneously. Circuit arrangements. Figs. 5 and 5a show a final group selector NW and a panel connector LW in a system in which the wanted number is dialled on a base of twenty and consequently the subscribers' lines are arranged in 400-line groups, which are subdivided into 100-line groups each served by a number of panel connectors comprising five brush sets. A group selector NW, Figs. 5 and 5a of the panel type, comprising four brush sets Ksa - - Ksd having access to the four sets of panel connectors respectively in a wanted 400- line group, is engaged from a preceding switch stage, and two series of impulses are sent on a base of twenty to select a wanted line. If, for example, a connector of the third hundred is required to be set upon the twelfth line in the fourth 20-line group, first fourteen and then twelve impulses must be sent. The first series of fourteen impulses are recorded on a register HW (at the group selector) which (1) causes the third brush set Kst of the group selector NW to select an idle connector in the wanted 100-line group, and (2) causes an associated impulse sending device to transmit the necessary four impulses to cause the wiper-choosing switch BW to select that brush set of the connector having access to the wanted 20-line group. The next series of twelve impulses steps up the rack t and the brush carriage is then lifted until the selected brush set engages the wanted line. An impulse sender is provided with twenty finger holes arranged as shown in Fig. 6 in two concentric rows in staggered relationship. The holes corresponding to impulse series 11 to 20 may be marked with code letters to avoid confusion. In response tu the first impulse series, the line relay A is energized and closes a stepping circuit for the magnet L of the register HW over contacts in the first position of the sequence switch S. The register HW is thereby advanced to its fourteenth position and upon relapse of the slow release relay V, the sequence switch S is driven over off-normal contact h into its second position in which the clutch magnet K, Fig. 5a, of the group selector NW is engerized over wiper l2 and a back contact nc5 of a test relay NO associated with the third brush-set Ksc. When this brush-set engages a trunk leading to an idle connector, say the one shown, in the wanted hundreds group, the test relay NC energizes over the fourth wire 6c, opens the clutch circuit, connects up the brushes a, b, c, drives the sequence switch into its third position, and by short-circuiting its right-hand winding causes the response of relay Y. The next series of twelve impulses is sent over contacts closed in the third position of the sequence switch and the a-wire to the connector stepping magnet E which lifts the rack t. On the relapse of the slow-release relay V a series circuit is closed over the b-wire for the clutch magnet H, Fig. 5<a>, and relay B, the high resistance of the latter preventing the response of the magnet H, but the relay B responding and causing the sequence switch to be driven through positions 4 to 8. As the switch passes through these positions one to five impulses are sent over the c-wire according to which of the contacts in these positions is earthed over the wiper l1 of the register HW. Since the register HW in this instance is set to its fourteenth position the contact 7 is earthed and four impulses are sent over the c-wire to the stepping magnet D of the brushchoosing switch BW which connects up the brush set serving the wanted 20-line group. In position 9 of the sequence switch the high-resistance lefthand winding of relay B is cut out of the circuit of clutch magnet H which lifts the connector brush-carriage until the selected brush-set engages the wanted line and the contacts G are opened. The magnet H and the relay B energize, the latter driving the sequence switch into its tenth position in which a test relay P is connected to the c wire. If the wanted line is idle the relay P energizes and marks it busy by shortcircuiting its right-hand winding. The increased current over the c-wire also causes the response of relay X which cuts off the magnets E. H and switches through the talking wires. At the end of conversation the sequence switch advances in known manner to its seventeenth position in which the release magnets U, Z are energized.