Patent GB-391123-A (GB)
Title: Improvements in automatic switches for use in telephone or like systems
IPC: H01H67/16
Filed: 1931-10-14
Abstract: 391,123. Automatic exchange switches. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, and SAXBY, R. N., 36, Millersdale Road, Mossley Hill, both in Liverpool. Oct. 14, 1931; No. 28598. [Class 40 (iv).] A bi-directional switch is provided with the following features : (i) the longitudinal and rotary magnets are mounted in the same horizontal plane with the operating mechanisms, also in that 'plane, the magnets being of substantially identical construction, (ii) the spring sets are all mounted on a horizontal plane above the magnets, the vertical and rotary off-normals and the cam springs being operated by the same member, (iii) the wiper carriage moves along a fixed shaft and is restored in both directions by a single helical spring, (iv) the wipers are of particular light construction and are clamped together by eyelet holes, one of which forms the cord hole, (v) rotary release, for testing over a second P.B.X. level, is effected by re-operation of the vertical magnet, (vi) release, which is normally rectangular, is direct if initiated before rotary motion has taken place, (vii) the P.B.X. bank is hinged to the front of the switch and is formed of plates, terminals being broken off to mark the termination of groups, (viii) vertical wipers do not partake in the rotary movement of the switch, (ix) relays and condensers are mounted on a unit hinged above the spring sets, (x) automatic centring of wipers and (xi) the wiper shaft is supported by detachable side and transverse members supported from the main frame. General arrangement. The switch comprises an upper plate 10 on the front of which two members 11, 12 are mounted. The shaft 15, about which the wiper carriage moves, is fixed to the bridging members 13, 14 as indicated in Fig. 1. The rotary magnet 19 is mounted on the plate 10 and its armature 20 controls pawl 24 whilst the vertical magnet (not shown). is of similar construction to 19 and is mounted on the opposite side of the plate 10 so that its armature controls pawl 26. The axes of the two magnets are in the same horizontal plane, but the axis of the vertical magnet is turned through 90‹ with respect to that of the rotary magnet. During vertical movement the wiper carriage is retained by the holding detent 30 whilst the plate 37 co-operating with comb member 38 holds the carriage against vertical release during rotary movement, the rotary detent 35 holding the carriage in its rotary position. The switch is released by moving the carriage into its twelfth rotary position in which the plate 37 leaves the comb 38 and the switch restores in a vertical direction, and then rotates into its normal position, both movements being controlled by spring 39. The wipers 40, 41 are of flexible metal, are insulated from each other and from their supporting bracket 42, and are fixed together by means of soft metal eyelets 43 and 44, 44 constituting the cord hole. Rotary or vertical release. For P.B.X. working the switch is arranged to test over more than one level. The rotary holding detent 35 is provided with a projection 45 (see Fig. 2) which co-operates with the vertical pawl 26 so that if the vertical magnet is re-energized after rotation has taken place the rotary detent is removed and the switch restores in a rotary direction. If the switch is .to absorb an initial digit, it is necessary that the switch shall restore quickly after vertical motion and for this purpose a small magnet (not shown) is provided which, when energized, withdraws the vertical holding detent 30 so that the switch restores directly. P.B.X. bank. The P.B.X. bank is composed of metal plates, the two plates constituting a single level being separated by insulation 87, Fig. 5. The plates are mounted on pillars 46, 47 and are held in position by skewer 48. The bank is hinged on to the front of the switch, as shown in Fig. 5, so that it can be swung out of position when necessary. The last one of the group is marked by breaking off the particular contact and Fig. 4 shows a typical level accommodating four groups of 7, 3, 8 and 2 lines respectively, the P.B.X. wipers being shown standing on the last line of the first group. Spring sets. The spring sets, of which only one set is shown, are all mounted on the plate 56, Fig. 5, which is readily removable as a single unit, or from which the sets may be removed by withdrawing the single fixing screw, a bumped-up portion of the plate co-operating with a second hole in the fixing bracket to hold the sets in position. As illustrated, the sets are of the anti-bounce type, the separating insulators having extensions 63 to hold portions of the stationary springs rigid. In the drawing the switch is shown lowered away from the operating mechanisms. When the switch takes its first vertical step, projection 58a allows 60 to move anticlockwise and the off-normal spring set, normally under strain, is operated. When a level is attained at which the operation of normal post springs is desired, the arm 59 will bear against rollers such as 61, 62 and levers NP1, NP2 will be tilted in the direction of the arrows to operate sets such as 57. On the first rotary step roller 64 leaves 65 and rides out on to the cam surface of 58 thereby operating the rotary off-normals and on the eleventh rotary step 58a engages roller 66 to operate the cam springs. In the twelfth rotary position the plate 58 leaves the comb 38 to allow the switch to restore, 58a leaves 66 to allow the cam springs to restore and slot 58c accommodates 64 to restore the rotary off-normals. At the same time the pin 68 moves the left-hand end of 59 to restore the normal post-springs. The lower ends of the rollers 64, 66 are cut away to prevent the operation of the rotary offnormal and cam springs during the rotary release motion. The vertical and rotary interrupter springs are mounted on the ends of the plate 56, the rotary springs being operated directly by a projection on the armature 20, Fig. 1, whilst the vertical springs are operated by means of a bell-crank lever. Vertical wipers. Two vertical wipers may be provided, the construction of these and of the relative banks being readily appreciated from Fig. 7. Mounting. The relays and condensers are mounted on a plate above the spring sets, which is arranged to swing back to give access to the mechanically operated spring sets. When the switch is placed in position, the plate 10, Fig. 1, sits on a shelf plate below which the multiple is fixed, the hooked clamping members 96 engaging the multiple supporting pillars to ensure correct centring. In an alternative arrangement, the supports 11, 12 are not provided, a bridge piece, to accommodate the lower end of the fixed shaft 15 of the switch, being carried by the bank rods. The Provisional Specification also states that the vertical and rotary movements may be arranged as separate and quite distinct units so that neither the vertical nor the rotary movements are burdened by parts having a purely rotary or vertical movement respectively. Specification 391,151 is referred to.