Patent GB-254373-A (GB)
Title: Improvements in electromechanically controlled systems and switching apparatus therefor
IPC: H04Q3/00
Filed: 1925-03-30
Abstract: 254,373. Aldendorff, F. March 30, 1925. Automatic exchange systems; selectors. - Relates to a consttuction of spring driven selector and to circuit arrangements for using such a selector as a call - finder, group selector or connector. Hunting and numerical movements of the selectors are both controlled by a single magnet which when energized allows the wipers to be driven by a spring and on falling back stops them. In one construction this magnet also controls the re-winding of the spring. The selectors may have several sets of wipers, the sets being relatively displaced along the axis of the shaft and also angularly. Construction of switches and terminal banks, Figs. 1 .. 4. The bank terminals are embedded in arcuate strips of insulating material held between metal plates 10, 11 by screws 9 and are provided with soldering tags arranged as shown in Fig. 4 to admit of bare wire multipling. The remainder of the switch is carried by a plate 14 secured by means of screws 15 passing through threaded collars 16 to members 12, 13 extending from the plate 11. The wipers are threaded on a square section tube 19 pinned to the wiper shaft 22 and are held by a nut 20. The wiper shaft is held in a given angular position by a detent 34 controlled by a magnet 17 and co-operating with a ratchet disc 23 secured to the shaft, against the action of a spring secured at one end to the shaft and at the other to a sleeve 24. The shaft is adjustable longitudinally by the threaded collar 28. When the magnet 17 is energized the wipers fly round until it falls back. When the switch is released, the magnet 17 is again energized and the wipers fly round until a stop member 46 pivoted to the frame 14 enters a slot in the disc 23. In this position the magnet is released at off normal springs 51 controlled by the wiper shaft. The spring is rewound by the back-stroke drive magnet 18, the stepping pawl 37 of which co-operates with a ratchet disc 25 on the sleeve 24. When the spring is fully wound, the arm 30 on the sleeve disengages the member 46 from the disc 23. At the same time the magnet 18 is disconnected by the springs 52 which are. controlled bv the sleeve. The switch may be used as a call-finder, group selector or connector with slight modifications and gives access to 50 lines over the wipers a, b, c and a further 50 over the wipers a<1>, b<1>, c<1>. One or more single or double-ended controlling wipers d, e are provided also according to the position in which the switch is to be used. Modified switch construction, Figs. 8 and 9, with a single magnet for controlling and rewinding. The disc 1<a> on the wiper shaft is held by a detent 15a under control of the armature 12a. When the magnet is energized the detent is released and the wipers fly round. The arm 16a on the armature moves the pawl 17<a> forward to engage the next of the oppositely directed ratchet teeth on the disc 2<a> secured to the driving spring and rotatable round the wiper shaft. When the switch is released the wipers fly round until a projection 19<a> on the disc 1<a> reaches a. stop 20<a>. The magnet 13<a> then receives impulses and steps round the disc 2<a> until a member 21<a> forces the stop 20a out of contact with the disc 1<a>, the circuit of the magnet being broken at the same time. Call-finder, Fig. 5. Line relay 100 marks the subscriber busy to connectors by disconnecting the wire 134, and calling to the finders by disconnecting his marking terminals 109, and energizes the starting relay 110 of the next idle finder to be used. Control magnet 113 releases the wipers which fly round until the dead terminal is reached, whereupon the magnet 113 stops them, switching relay 115 pulls up in series with cutoff relay 103, and impulse relay 200 and release relay 203 of the group selector pull up. Relay 203 holds up relays 115 over its low resistance winding and energizes relay 117 which locks up and extends the starting wire 130 to the next idle finder. Group selector, Fig. 6. In response to the hundreds digit, the wipers are whirled past a corresponding number of groups g<5>, g<6> &c. At the beginning of each impulse the control magnet 213 is energized over 206, 209, e<5> and at the end over 221, 222, e<5>, the dialling relay 207 being energized by the first impulse and holding up until the end of the digit. Between two short terminals the magnet is kept energized over 220. After five groups have passed a second set of a, b, and c wipers and terminals becomes operative but the same set of e terminals is used again. The relapse of the dialling relay disconnects the e terminals and connects up the cwiper to complete a circuit 225 (say), 227, 226, 213. The sluggish relay 227 in pulling up short circuits itself to allow the control magnet to be energized. The control magnet locks itself to the c-wiper and energizes relay 239 which locks up. When a dead c-terminal is found, magnet 213 stops the wipers and switches through the a and b wires. Line relay 300 and release relay 303 pull up in the connector, the latter sending back battery to mark the connector busy and energize relay 227 (which owing to the energization of relay 239 does not now short-circuit itself). Relay 227 disconnects the relay 200 from the line but makes a fresh circuit for it. Connector, Fig. 7. In response to the tens digit the wipers are whirled past a corresponding number of groups G5, G6, &c. At the beginning of each impulse the control magnet 320 is energized over e, 312, 308 and at the end. over e, 316, 310. In the intermediate positions the magnet is held up over e, 323, the dialling relay 324 being energized by the first impulse and holding up till the end of the digit. As in the group selector, there are two sets of a, b, and c terminals and a single set of terminals d, e. At the first step, springs 12 change. over and relapse of relay 324 at the. end of the digit makes a circuit 328, 329 for relay 327 which locks up, disconnects the short e terminals and connects the impulse wire 309 to the wiper 332 of an auxiliary switch of back stroke drive type. Each of the units impulses energizes the control magnet 320 over 309, 332, d, and the stepping magnet 336 of the auxiliary switch over 339, 340. The connector wipers move one step at the beginning and the auxiliary switch takes a step at the end of each impulse. Modified connector. The stepping of the connector may be controlled by a relay in place of the wiper arm 332. Prior to the units digit, this relay is energized over a high resistance winding, a front contact of the impulse relay and the dterminals, and the winding of the control magnet which is unable to pull up in this circuit. Over a front contact the relay connects up the odd dterminals and over a back contact the even eterminals to the impulse wire 309. When the impulse relay falls back for the first time it energizes a locking winding of the relay, disconnects the energizing winding and energizes the control magnet over the first d-terminal. The connector therefore takes one step. At the end of the impulse the relay is unlocked, and the next impulse causes the connector to take a step and thus allow the re-energization of the relay over its first winding. Ringing current. The relapse of dialling relay 324 completes a test circuit 307, 358, 356 (springs 111 having been moved off normal by the auxiliary switch). If the line is idle, test relay 356 pulls up in series with the cut-off relay and sends out ringing current from 363 over the ringing cut off relay 364. The ringing current is made intermittent by the auxiliary switch which is now stepped continuously in a circuit 370, 369, 367. When the subscriber replies, relay 364 energizes relay 373 which locks up over the loop, completes the talking connection and disconnects relay 364, 327. Busy signal. If the test relay does not pull up, a busy signal is sent back from 390, a second winding 395 on relay 373 inducing tone currents in the line winding. Release. If the called party hangs up first, the relapse of relay 373 energizes relay 379 which cuts off the line relay 300. The relapse of relay 300 when either subscriber hangs up, releases relay 303 to energize the control magnet 320 over 382, I1. When the wipers reach normal, this circuit is opened at I1. During the setting up of the connection, the winding magnet 383 is energized over 384, 307 to cause the change over of springs II associated with the hollow shaft and when relay 303 falls back, an interrupter circuit 367, II is made for it. When the spring is fully rewound, contact II is opened. The auxiliary switch is restored in a circuit 336, 385<1>, 367. The relapse of relay 303 releases relay 227 in the group selector, and when the calling party hangs up relays 200, 203 fall back and the control magnet 213 is energized over 13 which opens when the wipers reach normal. The winding magnet 263 which received a preliminary impulse during the setting up of the connection to close contact II3 now receives impulses from 265 until the winding disc reaches normal. The release of relay 203 also releases the finder switching relay 115 which completes an interrupter circuit for the winding magnet 163, and energizes the control magnet over 15. When the wipers reach normal 15 opens and when the spring is re-wound 133 opens. The contact 133 was closed initially owing to an impulse delivered to the winding magnet from a contact (not shown) controlled by the control magnet.