Patent GB-177799-A (GB)
Title: Improvements in and relating to automatic selectors for automatic telephone systems and the like
IPC: H01H67/12
Filed: 1922-03-31
Abstract: 177,799. Alfani, G., and Mazza, L. April 1, 1921, [Convention date]. Selectors and associated switchboard apparatus. - In an electric selector particularly for use in automatic exchange telephone systems, the terminal contacts are formed of flat bars or rods running parallel to one another and fixed in supporting plates of insulating material arranged transversely of the bars so as to form a succession of switch-banks separated from one another by the supporting plates. Another feature of the invention comprises the use of an electromechanical sequence switch, which in addition to changing successively the internal circuit arrangements of the selector in known manner, also modifies the mechanical arrangement of the selector to prepare it for movement in either of two directions, to bring about its release or to effect other desired operations, the same stepping magnet being used to rotate the sequence switch and also to move the brushes in both directions. The invention is described as applied to both two-coordinate and single co-ordinate switches. Method of multipling and arrangement of selectors. Two groups of 25 terminal bars representing 25 subscribers' lines are shown in Fig. 1. each group arranged in five vertical rows of five bars, corresponding bars in each group, such as a1 b1, a2 b2, &c., being allotted to each subscriber's line. The bars are supported and spaced by plates 26, 26<1>, 26<11> of insulating material, which also serve to separate the banks of adjacent switches. In the Figure, the brushes of two adjacent switches are shown, the bar sections of which are separated by a plate 26<1>. Each group of 25 bars is served bv a brush having two curved springs 28, mounted on insulating strips 31, but electrically connected together. Both brushes are first moved horizontally to select corresponding vertical rows of bars in each group, and then vertically to embrace two selected bars in these vertical rows. The number of conductors allotted to each subscriber's line may be increased by increasing the number of bars and brushes. Fig. 2 is a sectional view of a bank of 100 bars, representing 25 lines of four conductors. For the purpose of demonstrating two methods of brushing, the bank is divided into two groups of 50 bars. The brushes 32 of the lefthand group are similar to those shown in Fig. 1 with the exception that the two springs are insulated from one another, and instead of embracing a single bar they embrace two bars corresponding to two conductors of the same line. In the right-hand group the springs are so shaped as to contact with a corresponding pair of bars by being thrust between them. Construction and operation of selectors. Fig. 3 shows a two-co-ordinate selector arranged according to the invention. The electromechanical sequence switch comprises a number of discs 35, 36 &c. mounted on a shaft 34 rotated by a stepping-magnet 72 by means of a ratchet and pawl 52, 84. The discs 35, 36 &c. are formed with irregular peripheries, which besides operating contact springs, such as 49. in known manner, operate levers 39, 40, 41 to cause mechanical changes in the condition of the selector. A single stepping magnet 72 actuates the brushmoving mechanism and also steps round the sequence switch, the lever 39 in certain positions of the latter, raising, against the action of a spring, a sliding rod 42 carried in guides formed on the frame 46, and thereby bringing the lever 74 opposite the armature 73 of the magnet 72 in place of the lever 75. According to a modified arrangement the sliding rod 42 instead of moving the levers 74, 75, controls a link pivoted to the armature 73 to bring the latter into operative relation with either of the levers 74, 75. In other modifications described, the ends of the levers 39, 40, 41 rest in grooves in the peripheries of the discs 35, 36, &c. or they may be actuated by crowns of distinctive profiles, mounted on the sides of the discs. In operation, the stepping magnet 72 first receives an impulse, and the lever 74 being opposite the armature 73 the sequence switch is driven from position I to position II. In position II the levers 39 and 40 are actuated, causing the sliding rod 42 to be lowered and the rod 43 to be lifted. The lowering of the rod 42 allows the stepping lever 75 to move, under control of a spring, to a position opposite to the armature 73, whilst the rod 43 causes the retaining pawl 86 to engage with the rack 58 formed at one end of the brush-controlling shaft 53. The brush carriage 30 is mounted on a second shaft 54 parallel to the shaft 53, and is movable in a vertical direction between guides 67 formed on the shaft 54. The shaft 54 also carries on its left-hand extremity a sleeve 60 provided with two arms 61, 62, Fig. 4. The arm 62 is provided with a fork in which rests a rod 63 mounted on the sliding rod 44, and of such length that it remains in the fork even when the shaft 54 has traversed its full distance. In position II of the sequence switch the rod 44 is in its raised position and the lever 61 is inserted into a slot 57 in the shaft 53, thereby locking the two shafts 53, 54 together. The first series of numerical impulses is now sent, and the stepping magnet 72 actuates the lever 75 to move the shaft 53, and with it the shaft 54, a corresponding number of steps, to bring the brushes 27 below two selected vertical rows of bars in the bank 21. At the cessation of these impulses, a change-over magnet 47 is energized, which raises the sliding rod 42 and again brings the lever 74 under the control of the stepping-magnet 72, which now receives a further impulse and drives the sequence switch into position HI. In this position the lever 75 is brought under the control of the stepping magnet 72, the slide rod 44 is depressed, and a projection 65 thereon enters a slot 59 on the shaft 54, which is thus locked to the frame 46. At the same time the shaft 53 is uncoupled from the shaft 54 bv the withdrawal of the lever 61 from the slot 57. A second series of impulses now moves the shaft 53 a further corresponding number of stens. This movement. however, (since the shaft 54 is locked to the frame), is transmitted from a rack 70 on the shaft 53. to a pinion 68 mounted on one of the guides 67, and thence to a rack 71 on the brush carriage 30, which is thus moved in a vertical direction to engage the wanted bars in the previously selected rows. Other equivalent methods of raising the brush carriage 30 are described, by means of toothed wheels or sectors, levers, inclined planes or eccentrics. On the cessation of the second series of impulses the magnet 47 is again energized, the lever 74 is brought opposite the armature 73. and a further single impulse causes the sequence switch to be driven into position IV. The subsequent positions of the sequence switch may be utilized for any desired operations, such as testing, ringing, metering &c. In the present instance, release is effected in position VI in which a single impulse restores the sequence switch to position I, in which the slide rod 43 releases the retaining pawl 86, which permits the shaft 53 to move to the right until the lever arm 61 strikes against the collar 55 and enters the slot 57, after which both shafts 53, 54 together :nove to the right until the collar 56 engages the frame. According to modifications, the shafts 53, 54 may be arranged parallel to the terminal bars, or one may be arranged to slide within the other. In the modification shown in Fig. 6, the independent movement given to the brushes to engage wanted contacts in selected vertical rows is a rotarv one. The brushes 27, Figs. 6 and 7, are radially mounted on the shaft 90, which is rotated by the stepping magnet 72 (on the second series of impulses being sent). through a third lever 94 interposed between the levers 74 and 75, and brought opposite to the armature 73 by the slide rod 42 in position III of the sequence switch. Movement of the lever 94 is transmitted through a second lever 95 to a pawl 97, which acts on a longitudinal rack 93 on the shaft 30. When, on completion of a conversation, the sequence switch is restored to position I, the slide rod 43 releases both retaining pawls 86, 98, and the shaft 90, under the action of opposing springs or other forces, first rotates until the brushes are clear of the bars, and then moves to the right until the collar 91 engages the frame 46. According to another modification the brush carriage is mounted as in Fig. 3. but is given a vertical movement by a pinion and rack, the rack being formed on the carriage 30 and the pinion mounted on the shaft 53, which is rotated by the second series of impulses in the manner shown in Fig. 6. The invention may be adapted to single co-ordinate switches by dispensing with the horizontal movement of the brush carriage in any of the above constructions, and using any of the previously described arrangements for obtaining the second individual vertical or rotary movement of the brushes, in order to obtain a single co-ordinate movement. In the construction shown in Fig. 10, the brushes are mounted on a carriage 30 which is moved vertically, between guides 67 on the frame, by means of a rack 107.