Patent GB-191328502-A (GB)
Title: Improvements in Switching Apparatus for Interconnecting Telephone Lines by Electro-mechanically Controlled Switches.
Inventor: ALDENDORFF FRITZ
Filed: 1913-12-10
Granted: 1915-07-15
Abstract: 28,502. Aldendorff, F. Dec. 10. Automatic and semi-automatic exchange systems.- A calling subscriber T', Fig. 1, is connected by a quick-acting call-finder F to a disengaged group selector GW pre-selected by a switch VS. A second connexion is then made by a finder LF of a simpler but more slow-acting type, and the quickacting finder F is released and connected by the switch VS to the next disengaged selector, ready for further service. This arrangement ensures a connexion being made before the calling subscriber sends in any impulses, but does not necessitate the employment of more than two or three of the expensive quick-acting finders for each group of subscribers. In the system described, these groups include 100 subscribers each, but they may comprise a number several times as great. The quickacting finders are two co-ordinate selectors comprising main and brush-choosing switches which operate under the control of units and tens guidewires, two of which are grounded by the calling- subscriber's line relay. The brushes of the main and brush-choosing switches are arranged to be normally at the middle point of the terminal banks, and since these switches execute their movements simultaneously, the maximum time required in making a connexion is the time occupied by a switch in taking five steps. The slow-acting finders, on the other hand, are single co-ordinate switches of a simple type. The change-over of the connexion may be effected at any stage of the operation of the group selector GW or connector LW. In the arrangement described, it occurs between the tens and units selecting operations. The system indicated in Fig. 1 is shown in detail in Figs. 4 to 10, which constitute a single diagram, Figs. 4, 5, and 6 being placed side by side. Fig. 7 above Fig. 5, and Figs. 8, 9, and 10 above Fig. 7. Construction of switches. A construction suitable for the main switch of a quick-acting callfinder is shown in Fig. 3, the brush-choosing switch being similar. The shaft S can be driven in either direction by energizing solenoids e1, e2, which cause a plate d to be attracted against disks d1, d2 on a driving-shaft s1. According to the direction in which the shaft S is turned, one or other of two off-normal contacts c1, c2 is closed by a plate ds having a pin which works in an inclined slot of a plate d3. An off-normal switch OS of ordinary type is also provided. In the system shown in Figs. 4 to 10, the reversible driving-mechanism of the finder F1 is assumed to be of ratchet type. The selector GW and connector LW are S@rowger switches. Quick-acting finder F1, Figs. 4, 5, 6. The brushchoosing switch of a finder F1 is shown at W<1>, Fig. 5, the main switch being represented by the sets of brushes wa0, wb0, wc0, wd0 ; wa1, wb1, wc1, wd1; etc. The test wipers wp, ws of these switches appear in Fig. 4. The energization of the line relay l59, Fig. 4, of a calling subscriber S59 energizes relays m2 m<1>2 which control the clockwisemovement magnets E2' E<1>2, Fig. 6, of the brushchoosing and main switches of the finder. (If the subscriber S04, for iustance, had originated a call, the relays m1, m<1>1 controlling the counter-clockwise magnets E1, E<1>1 would have been energized.) The relay l59 also grounds the tens guide-wire 5<1> and units guide-wire 9, and energizes a starting-relay FS. This relay opens the circuit 111 to prevent the energization of a second line relay while the first calling line is being found, and momentarily closes a starting-circuit St through the magnets E2, E<1>2. The main and brush-choosing switches are thus given a first step in a clockwise direction. The off-normal switch OS1 is thereby operated and extends the starting-circuit St to the next idle finder, such as F2, at the same time connecting the magnets E2, E<1>2 to an interrupter 133. The main and brush-choosing switches continue their movements until the circuits of the magnets E2, E<1>2 are opened by the test relays tp, sp, which are energized when the test wipers wp, ws arrive on the contacts of the grounded guide-wires. The calling line is now connected through the brushes wa5, wb5 of the main switch and through the brush-choosing switch W<1>, to the line a, b and a circuit is closed for a relay CR<2>, which connects the line a, b to the switch VS, Fig. 7, through the wipers of which it is further connected to a pre-selected idle group selector GW, Fig. 9. The relay CR<2> locks itself up in series with the subscriber's cut-off relay co59, which deenergiz?s the relays l59, FS, m2, m<1>2, so that a second call in the same group of subscribers can now be dealt with. Slow-acting finder LF, Fig. 8. The starting- impulse in the wire St, which initiates the operation of the quick-acting finders, is also transmitted through the wires 200, 207 to the magnet 214, Fig. 8, of the finder LF, which is thus moved out of i's normal position, and the magnet 214 is then energized by the interrupter 218 over the offnormal contact 217 until its circuit is opened by the test relay 220. This relay is energized, when the calling line is reached, by a circuit through the wiper df, Fig. 8, and the wiper wd5 of the quickacting finder. Group selector GW, Fig. 9. The relay 231 is energized at the contact 233, Fig. 8, when the slowacting finder leaves its normal position. The relay LR is energized over the calling line as soon as the quick-acting finder completes its operation, and energizes a relay RR. During the current interruptions which represent the hundreds digit, the re'ay RR remains energized, in spite of its being short-circuited each time the line relay closes its back contact 227. At the first interruption, a ralay CR is energized, and as long as the interruptions continue, this relay remains energized in series with the relay RR, although it is momentarily shortcircuited each time the line relay closes its front contact 228. Each interruption energizes the vertical magnet HM. At the conclusion of the series, the relay CR de-energizes and momentarily energizes a magnet SM<1>, which trips the side switch to its second position. The rotary magnet DM is now brought into circuit and rotates the wipers until an idle connector is found, the side switch being then tripped to its third position by a second magnet SM<2>, which is electrically controlled over the test wiper and mechanically controlled by the rotary magnet, in known manner. Connector LW, Fig. 10. The second and third series of current-interruptions are repeated to the vertical and rotary magnets HM1, DM1 by the relays LR<1>, RR1, the operation of these relays and of the relay CR1, which controls the side-switch magnet SM3, being similar to that of the relays LR, RR, CR, Fig. 9. During the tens impulses, the relay LR' is energized in series with the relay 259, Fig. 9, but during the units impulses, both windings of the relay LR' are bridged across the line. Change-over of connexions from the quick finder F1 to the slow finder LF ; release of the finder F1 and connexion thereof to a disengaged group selector by the switch VS. The relay 259, Fig. 9, which is energized in series with the connector line relay LR<1> during the transmission of the. tens impulses, controls a slow-release relay 261a, which controls the side-switch magnet SM<2>, so that at the termination of the tens impulses, the side-switch is moved to its fourth position. In this position, ground is connected, over the arm 249, (1) to a relay 280, Fig. 8, which locks itself up and connects the calling line to the selector GW through the finder LF, and (2) to a relay 262, Fig, 7, which locks itself up through the test wiper 206 and energizes the magnet DMv, which advances the switch VS to the terminals of the next disengaged selector. The relay 262 also closes the circuit of the release relay rl, Fig. 6, of the finder F1. The relay rl locks itself up and de-energizes the relay CR<2>, which connects the interrupter 133 to the counter-clockwise magnets E1, E<1>1, the circuits of these magnets having been prepared at the contacts b1, b<1>1 of the two-way off-normal switches DS1, DS2 when the main and brush-choosing switches executed their original clockwise movements. These switches are therefore now restored to normal position at the middle points of their terminal banks, and the starting-circuit St is again connected by the off-normal switch OS1 to the magnets E1, E2, &c., so that the finder F1 can be taken into use again when the next call arrives. The relay 220, Fig. 8, is now de-energized, but the circuit of the stepping-magnet 214 is kept open by the relay 239, which is energized in series with the calling-subscribar's cut-off relay c059. Busy signal ; supply of ringing-current. In the third position of the connector side-switch, the test relay 300 is connected to the test wiper. If the wanted line is busy, the relay 300 fails to energize, and the busy signal 325 is connected to. the calling line ; but if the line is idle, the relay 300 energizes and connects up the ringing-relay RL. When the called subscriber replies, a relay 307 in the ringing-circuit responds to the increased current and energizes a ringing cut-off relay 309, which locks itself up and de-energizes the ringing-relay. Release. The connexion is released when either subscriber hangs up his receiver. The circuit of the connector release magnet AM1 and selector release relay 255 is completed, in the one case, by the de-energization of the relay RR1, and in the other case, by a contact 316 closed momentarily by the falling back of the armature of the called subscriber's back-bridge relay. The relay 255, Fig. 9, energizes the release magnet AM, and the release of the group selector unlocks the relay, 280, 239, Fig. 8, so that the magnet 214 is brought into circuit and steps forward the finder LF till it regains the normal position. Preventing connexion of two slow-acting finders LF to the same calling line. With the abovedescribed circuits, a