Patent GB-121474-A (GB)
Title: Improvements in or relating to Electric Selectors for Telephone Systems.
Inventor: HULTMAN CARL AXEL WILHELM
IPC: H01H67/12
Filed: 1918-12-06
Abstract: 121,474. Hultman, C. A. W. Dec. 11, 1917, [Convention date]. Automatic exchange systems and apparatus. - The movable wipers of two-co-ordinate non- numerical selectors, such as call-finders, have no normal position in respect of their movement in one direction (group selection), but move from an initial position in the other direction (line selection). The invention is described as applied to a call-finder system in which the lines are divided into two large groups A, B, and when a subscriber in either group removes his receiver, all the idle call-finders serving the double group are set in motion. Each call-finder has two sets of wipers Ku, Kn, one for each large group, and the wipers first move to and fro between the two main groups of wires till they find the row of contacts containing the calling line, and then upwards or downwards (according to the main group) until the corresponding set of wipers engages the calling line. Construction of call-finder, Figs. 3 and 4. The two sets of contact wipers k are arranged at opposite ends of a bar KB guided between rollers R1 on a carriage V, which is itself guided by rollers R2 on a fixed beam VB. The wiper bar KB is connected, by means of a projection LA, to an endless rope L, which passes round two rope pulleys LS1, LS2, arranged on stationary shafts, and round three pulleys LS3, LS4, LS5 mounted on the carriage V, the two latter pulleys being loosely mounted on the same shaft. The driving- pulley LS1 can be driven in one direction or the other from a rotating shaft by clutch magnets MK1, MK2, Fig. 2. A pivoted magnet VR normally locks the bar KB to the carriage V. so that the rope moves the carriage and bar horizontally, but when the magnet VR is energized, the bar KB is unlocked from the carriage, which is itself locked to the fixed beam VB, so that the rope moves the bar KB vertically. Contact springs KF1 - - KF6, Fig. 2, on the carriage V engage stationary contact bars KS1 - - KS6, while springs RF7, KF8, KF9 on the bar KB engage contact bars KS7, KS8, KS9 on the carriage V. Specification 13362/14 is referred to. Connexion to calling line. Each line has associated with it four contacts a, b, c, d in the terminal bank, contact c being connected to the subscriber's cut-off relay LyR and contact d to a front contact of the line relay LR. When a subscriber removes his receiver, his line relay LR puts selectable potential upon terminal d, and upon a terminal f common to the vertical row of terminals containing the calling-line. The line relay LR also energizes a common starting-relay SRu or SRn, which closes the circuit of relays F1R - - F5R, which in turn close the starting- circuits 4 for all the free call-finders having access to the calling line. The circuit 4 includes a clutch magnet MR2 or MK1 according as a reversing- relay HR is energized or not. Assuming that relay HR is de-energized, the clutch magnet MK1 moves the carriage V to the left, and when it reaches the end of its travel, a circuit 10 is closed for the reversing-relay HR, thereby energizing the clutch magnet MK2 so that the carriage moves to the right. At the end of its travel, the locking- circuit of relay HR is opened at contact 15, and the carriage moved to the left. When the group test wiper KF10 (or KF11) reaches the live terminal f, the horizontal test relay Ly, R1u (or LyR1n) is energized over circuit 6, and (1) locks up over circuit 7 and relays UR2, which disconnect the test relays of the other searching callfinders, (2) earths the terminal f to mark it busy, and (3) opens circuit 4 of the clutch magnet MR1 or MK2 and relay FR. The relay FR closes a circuit 13 to move the controlling sequence switch SOs into its second position, and also energizes a brake magnet MB. In the second position of the sequence switch (1) relays UR1 are energized to open the circuits 4 of the clutch magnets of the other call-finders, (2) the magnet VR is energized to change over the selector driving-mechanism, and (3) the clutch magnet MK1 (or MK2) is energized over circuit 16 (or 16<1>) to raise (or lower) the wipers over the terminal bank A (or B). When the calling line is reached, the vertical test relay LyR2 is energized over circuit 17, and (1) locks up over circuit 18, (2) energizes the subscriber's cut-off relay LyR over circuit 19, (3) energizes the brake magnet MB, and (4) moves the sequence switch SOs into its fourth position, in which the row test terminal f is no longer marked busy, and the calling line is connected over contacts S24, S25 to the selector trunk. When the switch SOs reaches its seventh position, relays UR1, UR2 are de-energized, so that the free call-finders may be used for another call. Release after conversation. After conversation, the sequence switch is moved into its ninth position, in which (1) the test relay LyR2 is de-energized, (2) the relay VR is energized, and (3) if the wipers have been moved upwards, the reversing-relay HR is energized over circuit 21. The down clutch magnet MK2 (or MK1) is thus energized over circuit 22 and moves the wipers downwards (or upwards) until they reach normal, when spring KF9 disengages bar KS9. Premature release. If the subscriber replaces his receiver while the wipers are moving vertically, the movement continues until they reach terminals g in the topmost (or lowermost) level, when the relay LyR2 is energized and moves the sequence switch into its fourth position and the call-finder restored.