Patent GB-262534-A (GB)
Title: Improvements relating to electric switches such as used in automatic telephone systems
IPC: H01H67/12
Filed: 1925-09-17
Abstract: 262,534. Siemens Bros. & Co., Ltd., and Humphries, H. E. Sept. 17, 1925. Automatic exchange systems and selectors.-Construction of selector, Fig. 1. A plate 6, rotatably mounted on a standard 2, has pivotally mounted thereon an arm 7 carrying a wiper arm 8 which is adapted to co-operate with bare-wire multiples arranged in curved bays B, The armature 12 of a reverse-drive magnet 11 on the plate 4 carries a pivoted pawl 14, which rotates a ratchet segment 3 fixed to the plate 6. In response to each dialled impulse, the magnet 11 gives three local impulses, by means of a make-andbreak contact 68, to shift the wiper-arm 8 opposite the first bay B or from one bay to the next. A retaining pawl 21 for the ratchet 3 is mounted on an arm of the armature 22 of a release magnet 44 mounted on the plate 4. When the arm 8 comes opposite the first bay B a projection 51a on the plate 6 releases a spring-pressed arm 67 which releases the offnormal contacts 54. The armature 28 of a magnet 27, mounted on either the plate 6 or the plate 4, carries a spring-pressed pawl 29 which rotates the arm 7, 8 through a ratchet sector 33 to find a free link. A detent pawl 38 is mounted on an arm 40 of a floating ratchet 41 on the spindle 2. When the caller hangs up, the release magnet 44 is energized. Its armature 22 thereupon withdraws the pawl 21 from the ratchet 3, which is retained in position by the pawl 14. An arm 25 on the armature 22 is also shifted so that a pawl 47 thereon rotates the ratchet 41 and withdraws the detent pawl 38 from the ratchet 33. The arm 7 thereon withdraws the wiper 8 under the influence of a spring. The magnet 11 is then energized and withdraws the pawl 14. The return of the plate 6 to normal restores the off-normal contacts 54. The magnets 44, 11 are then de-energized, the detent pawls return to the ratchets, and the pawl 14 feeds the ratchet 3 one step to its original position. The wires of a group in the multiple may be on a single arc, in which case the arm 8 contacts with the wires on one side only. A number of switches which co-operate with the same multiple may be relatively adjustable vertically thereto for wear. The multiple may be split into sections, part of the multiple being accessible to all the switches. Circuit for group selector, Fig. 4. In order that the selector may take three steps for each incoming impulse, relays P, Q are so arranged that relay Q is energized by alternate impulses, and at contact q3 extends a connection alternately to brushes 61, 63 of a commutator 6, Figs. 1 and 3, which connects these brushes alternately over brush 62 to a self-interrupting circuit of the magnet 11. Relay A energizes relay D over the incoming test circuit, and relay P energizes in a circuit q2, P(1), ql, a2, d2, t5. At the first impulse a short-circuit is removed from relay Q(1) at contact a2, and this relay becomes energized from the incoming test wire in a circuit t1, p1, Q(1), P(1), p2. The commutator 60 normally connects the brushes 62, 63 so that magnet 11 is now intermittently energized in a circuit 11, 55, 68, 62, 63, q3, d2, t5. After three steps the commutator disconnects the brushes 62, 63 and connects brushes 62, 61 and the magnet 11 ceases to operate. Meanwhile the re-energization of relay A after the first impulse closes a circuit over contacts a2, q1 for relays P(2), Q(2), and the relay P, the windings of which oppose'one another, relapses. When the contact a2 opens at the second impulse, relay Q falls back and closes a circuit over brushes 61, 62 for the magnet 11, and after three steps the commutator disconnects brushes 62, 61 and connects brushes 62, 63. At the end of the second impulse, relay P,is energized again, and the circuits are ready for a repetition of the same cycle. Contacts k1, k2, k3 are shifted at the first impulse, and relay D is held over a circuit d1, a1, c until the termination of the digit and then relapses and closes a circuit t5, d2, k3, a3 for magnet 27. When free terminals are reached relay T(1) is energized, locks itself by its second winding, grounds the test wiper, disconnects relay A, and switches through. On release, the opening of the incoming test circuit c de-energizes relay T which closes a circuit t5, d2, k3, a3 for magnet 44, which releases the ratchet 33, Fig. 1, and when the wiper arm 8 returns to normal, contact 55 is closed to energize magnet 11, which releases the ratchet 3.