Patent GB-450019-A (GB)
Title: Improvements in automatic switches for use in telephone or like systems
IPC: H01H67/16
Filed: 1935-01-08
Abstract: 450,019. Automatic exchange switches. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, and SAXBY, R. N., 36, Millersdale Road, Mossley Hill, both in Liverpool. Jan. 8, 1935, No. 651. [Class 40 (iv)] In an electromagnetic step-bystep switch of the vertical and rotary type wherein release does not take place over the setting path, the normally required adjustments of the stepping mechanism are effected from the front of the switch. The rotary detent prevents rotary movement of the switch when normal. The adjustments in question are for the detents, the front pawl stops and the restoring springs of the magnets. Adjusting screws facing forwards have slotted heads, others have hexagonal heads. The invention is described in connection with a switch of the type described in Specification 391,123, which is released by rotating it forwardly out of the bank. The switch frame comprises upper and lower platforms 8, 10 connected by a central vertical web to provide left and right-hand compartments for housing the vertical and rotary magnets of which only the rotary magnet 19 is shown in Fig. 1. The switch shaft 14 is a push fit at its upper end in a bracket 15 forming part of the frame and is clamped at its lower end by a clip 16 to a plate 13 carried by posts 11, 12 secured to the frame. The wipers and driving ratchets are carried by a sleeve slidable and rotatable on the shaft. The pawl 29 carried by armature 73 of the vertical magnet is limited as regards its upward movement by a screw 31 threaded through the frame and through a separate plate, the screw being locked by a further screw 14 passing through the frame into a hole tapped in the separate plate. The vertical detent 32 is pivoted at 33, controlled by spring 34, and adjusted by screw 35, locked, as described later. On the first rotary step, the detent 32 leaves the vertical rack 30 and the switch is prevented from falling back by an arcuate plate 41 which engages comb 42. The rotary magnet is adjustably mounted on the top platform 8 by arranging it to swing about the armature pivot 21 which passes into the platform. The magnet has a bolt 25 passing through an arcuate hole in the platform and secured to a plate 71, Fig. 5, rotatable about a screw 72. The armature spring 22 is adjusted by screw 23 passing through tapped holes in lugs on a bracket 24, the lugs being bent somewhat out of the parallel after tapping so that a locking effect is produced. A similar locking is provided for the previously described screw 35 of the vertical detent. The resting position of the armature is adjusted by screw 43. The rotary pawl 26 controlled by spring 27 is guided by an adjustable plate 37, the front pawl stop 38 being adjustable and locked by a screw 46 in a manner similar to the adjustable screw stop 31 of the vertical pawl. The rotary holding detent 39 pivoted on the same pin 33 as the vertical detent and controlled by spring 82 is adjusted by screw 40 locked in a manner similar to screw 23. On release, the switch steps forward out of the bank where the rotary pawl 26 enters a deep groove in the ratchet, a projection 48 on the pawl coming up against a stop plate 49 before the interrupter springs open to prevent self-interruption as described in Specification 440,346. The switch then falls back and rotates to normal under the control of spring 47 which is both stretched and twisted in the set position of the switch. In the normal position, the stepped end 50 of the rotary detent engages behind a projection on a profiled plate 41 to prevent accidental rotary movement of the switch. The spring sets are mounted side-by-side on the upper platform 8, the mounting plate of each set being fixed by a single screw and having a rearward projection engaged in a slot 75, the rotary off-normal set shown in Fig. 1 being operated by a lever 52 having a roller engaged by a cam 53 on the switch shaft. The interrupter springs of both the vertical and rotary magnets are operated as described in Specification 433,877. The mounting plate 55 for the relays is secured by screws engaging holes 56, 57 in the frame. Arrangements for mounting vertical wipers and for mounting the switch on the shelf are as described in Specification 431,348. Test jacks 60, wiper flex terminals 61 and a switch jack 78 are provided, the test jacks comprising slots in insulating material each housing a bowed spring located in the slot by a small tongue on the spring. A dust cover for the whole of the switch clips over the relay plate 55 and has slots engaging projections 64, 65 at the bottom of the frame structure.