Patent GB-295214-A (GB)
Title: Improvements in electric switching apparatus suitable for automatic telephone and other remote controlled systems
IPC: H01H67/06
Filed: 1927-02-04
Abstract: 295,214. Aldendorff, F. Feb. 4, 1927. Automatic exchange systems and selectors.- Stop-controlled selectors are driven by a spring which moves axially a worm meshing with a wheel on the wiper shaft, and which is re-tensioned by rotating the worm by an individual motor or a common power shaft. A single motor may be provided for the switches and tone and ringing generators and interrupters, and may be stopped when all the switches are in their normal positions. The switch may be used as a call-finder, allotting switch or numerical selector, Construction of switches. (1) Figs. 1 to 4 (16199/27). When the control magnet 25 is energized, an adjustable detent 22 is withdrawn from a toothed wheel 21 on the wiper shaft and a spring 18 forces a worm 17 slidably mounted on a shaft 14 and meshing with a worm wheel 19 on the wiper shaft to the left, thus rotating the wipers, the speed being governed by a centrifugal brake with an adjustable collar for varying the effective length of the springs. A flange 39 on the worm in moving clear of a lever 43, allows a spring 9 to force a member 8 slidably mounted on a power shaft 2, downwards, and a pin 12 engages one of a number of pins 11 formed on a ring projecting from a bevel wheel 7 loosely mounted on the shaft 2 and engaging a bevel wheel 13 on the shaft 14. When the wipers are stopped by the detent 22, the rotation of the shaft 14 causes the worm to move to the right until the spring 18 is re-tensioned whereupon the flange 39 re-engages the lever 43 to disengage the member 8 from the bevel wheel 7. A latch 57 is provided on numerical switches, for stopping them in a definite normal position by engaging a hole in the stopping wheel. The latch is disengaged by the flange 39 when the spring is re-tensioned. the wipers being held by the detent 22. The armature restoring spring 26 is adjustable by a screw 41 carried by a projection formed on the iron of the magnet. The bank may be adjusted by loosening the screws 37, 38. (2) Figs. 1 and 2 (3208/27). This selector has an individual motor 9 for re-tensioning the spring. When the wipers are released, a flange 27 on the worm engages a projection 28 on a disc 37 which it moves against the action of a spring until the motor circuit is completed over brushes 32, 33 and a segment 31. The disc 37 is held in this position by a detent 35 until the spring is re-tensioned when the flange 27 removes the pawl and the disc 37 is returned by its spring to the off position. (3) Fig. 1 (11745/27). In a modified arrangement for restoring the spring by means of a common power shaft, a flange 13 on the driving worm allows a spring 19 to move a pinion 20 slidable on the power shaft into mesh with a pinion 11 on the worm shaft 10. The worm is then rotated and when the spring is restored the disc 13 disengages the pinions. In a further modification the wiper shaft, instead of being fast with the worm wheel, is connected to it through a spring. The wipers are then driven partly by this spring and partly by the spring 14. Both springs are restored by the power shaft, the first by rotation of the worm and the second by its longitudinal movement. Call-finder. When a single call' is made, starting relay 110 pulls up its dotted armature, and the control magnet 125 in the finder shown locks to the test wiper. If the two calls are made simultaneously, 110 pulls up both armatures and starts a second finder (not shown). When the dead calling terminal is reached, the finder stops and switching relay 118 and cut off relay 129 pull up in series and lock themselves to battery returned over the holding wire by the group selector release relay. Battery on the holding wire also energizes magnet 225 of the allotting switch which moves off in search of an idle and unallotted finder. Group selector and connector. The circuits of these are identical with those shown in Figs. 3 and 4 of Specification 283,252.