Patent GB-343603-A (GB)
Title: Improvements in telephone systems
IPC: H01H67/12
Filed: 1929-11-26
Abstract: 343,603. Automatic exchange switches. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street, Chicago, U.S.A. Nov. 26, 1929, No. 36218. Convention date, Nov. 26, 1928. [Class 40 (iv).] The wipers of a selector are moved step by step in two directions at right angles in a single plane under the control of a single magnet and are restored to normal by a power-driven shaft common to a plurality of selectors. The setting movement in both directions is effected under spring tension. The selector is provided with a side-switch which is also restored to normal by power from the common shaft. Circuit arrangements are described for a system utilizing selectors constructed according to the invention as group selectors and as connectors. Construction of selectors, Figs. 5, 8. The selector rack comprises vertical angle irons 1 and steel bars 2 connected by horizontal angle irons 3 which form ledges on to which the flat plate 23 carrying the selector mechanism is adapted to slide. The wipers 54 are mounted on a member 33 adapted to slide on rods 30, 31 secured at their ends to rods 28, 29 which are in turn adapted to slide in brackets 25, 26 fixed to the base plate 23. A spring-controlled arm 39 tends to move the wipers 54 across the bank by engaging a U-shaped member 34 which in turn engages the member 33 and is adapted to slide on a rod 32 and in a slot 38 in the plate 23. This movement however is normally prevented by a stepped member 40 which engages the U-member 34 under the control of a flat spring 50. Movement of the wipers 54 into the bank 6 which is of the bare-wire-multiple type is effected by rotation of the rod 32 which carries a toothed sector 51 engaging the rod 28 and a toothed wheel 57 fitted with an escapement 38. The side-switch wipers 72 are mounted on a member 70 on a shaft 63. To one arm of the member 70 is connected through a rod 76 a toothed member 77 to which are pivoted a forked member 89 and an arm 80 which together act as an escapement under the control of magnet 98. In the normal position of the side-switch and member 77 a stop 102 with which engages a pawl 101 on the armature 99 of the operating magnet 96 is in such a position that when the magnet 96 is operated by impulses the projection 103 on pawl 101 engages the bent end 47 of lover 44 causing pawl 43 to advance stopped member 40 so that the wipers 54 are moved step by step across the bank. The wipers are normally opposite the first row of contacts so that the member 40 is so arranged that the wiper carriage 33 does not take a step until the second impulse is received. At the end of the impulses the release of side-switch magnet 98 moves toothed member 77 so that the side-switch moves to its second position and as a result of the movement of stop 102, the projection 103 of pawl 101 moves into engagement with a projection 60 attached to escapement 58 so that further intermittent operation of magnet 96 causes the rotation of rod 32 and the movement of wipers 54 into the bank. The spacing of the teeth on member 77 may be such that one operation of magnet 98 may advance the side-switch wipers two steps but by energization of a magnet 75 the armature of which carries a notch adapted to receive a projection on the shaft 63 the side-switch may be held in an intermediate position. On release, the momentary operation of magnet 18 causes a pawl carried by a bushing attached to a disc 12 to engage a ratchet wheel secured to a power-driven shaft 7 so that the disc 12 is coupled to the shaft for one rotation. A roller 15 engages the end of a pivoted lever 14 causing a hook at the other end to be inserted in a slot 53 of a member 52 carried by the rod 29 whereby the wiper carriage 33 is withdrawn from the bank 6. Shortly afterwards a roller 13 on the lower side of disc 12 engages a hooked lever 68 causing an arm 65 to engage with projections on members 39, 70 whereby the wipers 54 are restored in the other direction and the sideswitch also returns to normal. The leads to the selector wipers 54 are enclosed for protection in a helical spring tube 94 which slides on a flat strip of fibre during movement of the wipers. No external leads are connected to the side-switch wipers which merely provide bridges between various bank contacts. Circuit arrangements ; group selector, Fig. 9. The incoming selector leads are connected to the lower contacts 120, 128 in the banks of wipers 106, 109 and in position 1 of the side-switch these wipers connect the incoming leads to the line relay 95<1> which operates and energizes relay 97<1>. Impulses are repeated to selector magnet 96<1> in series with slow-release side-switch magnet 98<1>. At the end of the digit the movement of toothed member 77<1> advances the side-switch to position 2 and operates off-normal contacts 132. Wiper 108 now bridges contacts 125, 126 completing a circuit over off-normal contacts controlled bv rod 28<1> for magnets 96<1>, 98<1>. The selector takes one step into the bank and if the first line is busy relay 136 operates over contacts 122, 123 and wiper 134 and completes a new circuit for magnets 96<1>, 98<1>. The movement of the wipers releases relay 136 and magnet 96<1>. The wipers thus continue to advance into the bank until an idle line is reached when magnet 98<1> releases and advances the side-switch into position 3 in which the talking leads are connected through to the wipers 133, 135, wiper 134 is grounded over relay 136, and springs 110 controlled by wiper 108 are operated. The second group selector operates in a similar manner. Connector, Fig. 10 ; called line busy. Relays 95, 97 operate and the tens and units impulses are repeated to magnets 96, 98, the toothed member 77 being stepped during the inter-digital pause to advance the side-switch to position 1 and to change the direction of movement of the wipers. At the end of the units impulses the side-switch tends to move to position 3, but if the wanted line is busy, relay 75 is energized over wiper 219 and prevents movement beyond position 2 in which busy lead 230 is connected up. Called line free. The side-switch moves to position 3 in which ringing current is connected up over wipers 206, 204, 209, 207 and relay 203, and spring 210 is operated by wiper 205 to ground wiper 219. When the called subscriber replies, relay 203 operates and completes a circuit for magnet 98 which advances the side-switch to position 4 in which relay 203 serves as a feed relay for the called party. Release. When the calling party hangs up, the release of relays 95, 97 energizes the connector release magnet 18 and a relay (similar to relay 136, Fig. 9) in the second selector over conductor 231. The operation of this relay energizes the release magnet of the second selector which connects battery to contact 151 to operate relay 136 and magnet 18<1> in the first selector.