Patent GB-334124-A (GB)
Title: Improvements in or relating to automatic and semi-automatic telephone systems
IPC: H01H67/12
Filed: 1929-11-05
Abstract: 334,124. Telefonaktiebolaget L. M. Ericsson. Nov. 8, 1928, [Convention date]. Automatic exchange selectors.-Bi-directional selectors, arranged to move along and into a bare wire multiple bank, are driven by two shafts, a worm shaft and a shaft ridged to engage a rack on the selector arm, which are parallel to each other and to the direction of primary motion and the selectors are mounted on opposite sides of and use the multiple of a common multiple bank, the facing switches being staggered vertically to allow the selector arms to interleave when in operated position. If finder switches and final selector switches use the same bank, similar switches are mounted together and the "private wires " are cut at an intermediate point to give in effect separate multiples for the finder and final selector switches respectively. In the finder switch multiple the vertical multiple supports may be used for group marking purposes. Construction and mounting. The switches are mounted vertically above each other on opposite sides of a multiple frame, the switches on the one side of the bank being mounted centrally between the switches on the opposite side of the bank. As shown, the switches on opposite sides of the multiple are driven in different directions. but the mounting can be arranged so that identical switches will be suitable for use on either side of the bank multiple. The multiple wires, of which 9, 10, 11 represent a set, pass through holes in insulating strips 12 mounted on rods 13 which are secured to the frame or to the vertical .bars 16 which latter may serve as group marking terminals for finder switches. The selector arm 25 is mounted on a carriage 28 which is driven over the switch base 23 by means of the worm shaft 31, correct alignment being ensured by wheels 29, 30 which engage racks cut on the upturned edges of the base. The ridged shaft 33 .engages a rack 34 on the selector arm 25 and when the correct row of terminals has been reached the shaft 33 rotates to move the arm into the multiple bank. Connection between the incoming wires, which are joined to bars 55, 56 and 57, and the engaging tips 67, 68 and 69 is effected by brushes 58, 59, 60, 61, 62 and 63 which make contact, with the bars 55, 56, 57 and with the conductors 64, 65 and 66 mounted in the selector arm. When operated, relays 39, 40 bring the wheels 37 and 38 respectively into engagement with the wheel 42 mounted on the intermediate shaft 41. The shaft 41 can swing about a pin 43 bringing the wheel 47 into engagement with driven wheels 45 or 46 mounted on the constantly rotating shaft 44. The shaft 41 is moved about pin 43 by armatures 51 and 52 of relays 48 and 49 (See Fig. 3). A guard arm 78, provided to protect the projecting arm 25, is marked to indicate the horizontal position of the brush carriage and the contacts engaged are indicated by a bar 79 mounted on the selector arm. Operation as a group selector in a revertiveimpulse register-controller system. The magnet 48 operates bringing the wheels 47 and 46 into engagement and magnet 39 pulls up allowing wheels 42 and 37 to mesh. The worm shaft rotates moving the brush carriage, operating offnormal springs 70, and returning revertive impulses by means of apparatus not shown. When the required row has been reached 39 falls back and 40 operates enabling the shaft 33 to rotate' to drive the selector arm into the bank and secondary off-normal springs 71 change over. When a free circuit is reached magnets 48 and 40 de-energize stopping the switch. When the connection is released magnets 49 and 40 energize and wheels 47 and 45 and 38 engage to withdraw the selector arm from the multiple and when the arm is in its home position, springs 71 restore de-energizing magnet 49 and energizing magnet 48. Cog-wheels 42 and 37 now engage and when the selector carriage regains its normal position, springs 70 change over to release the magnets.