US1712243A - Automatic electric switching system - Google Patents

Description

y 7, 1929. F. ALDENDORFF 1,712,243

AUTSMATIC ELECTRIC SWITCHING SYSTEM Original Filled Feb. 14. 1922 4 Sheets-Sheet 1 y 7,?1929- F. ALDENDQEFF I I 1,712,243

AUTOUATIC ELECTRIc SWITCH'ING SYSTEM Original Filed Feb. 14. 1922 4 Sheets-Sheet 2 5 L65 L39 M5 May 1, 1929..

F. ALDENDORFF AUTOMATIC ELECTRIC SWITCHING SYSTEM Original Filed Feb. 14. 1922 4 Sheets-Sheet 3 m7 1 9 I i {I lzw'erziaz' IAldendorfl.

May 7, 1929. F. ALDENDORFF 7 AUTOMATIC ELECTRIC SWITCHING SYSTEM Original Filed Feb. 14, 1922 4 Sheets-Sheet 4 fiwezzi'or 5 Fade/1610 Patented May 7, 1929.

UNITED STATES PATENT OFFICE.

FRITZ ALDENDORFF, OF BERLIN-WILMERSDORF, GERMANY; CHARLOTTE ALDE1\T DOB-FF HEIRESS OF SAID FRITZ ALDENDORFF, DECEASED; SAID FRITZ ALDEN- DORFFASSIGNOB OF ONE-FGURTH T YAUL KOLISCH, OF NEW YORK, N. Y.

AUTOMATIC ELECTRIC SWITCHING SYSTEM.

Original application filed February l t, 1922, Serial No. 536,504, Patent No. 1,641,145, dated September 6, 1327, and in Great Britain August 6, 1921. Serial no. 100,292.

It is highly desirable to build the switches of electromechanical telephone systems in such a. manner that their movable contacts may reach any desired point in a contact bank in the smallest possible time. The speed of travel is, however, limited by the in ertia of the relays and magnets by which the movements of the switch wipers are con trolled. \Vhen a travelling wiper or wipers is to be stopped at a certain contact the re lay (or relays) that control the power or actuating circuit has (or have) to be given sutlicient time to act and with commercial relays this time generally amounts to be tween 5 to 1.0 thousandths of a second. For this reason a wiper through which the encrgizing current of a test relay or the like flows must remain in touch with the particular bank Contact in question for at least the said length of time. In addition to the relays the operating magnet and the circuit elements associated with the relay and mag net have more or less electrical and mechanical inertia so that with practical switches of known types a speed at which the wiper travels over about contacts per second is about the average speed that is compatible with reliable working. These figures are, however, only mentioned to provide a more or less general basis for indicating the ob jcct of the invention, but are not intended to limit its scope.

One proposed method of enabling a line finder with a bank of 100 to 500 contact sets to rapidly connect any bank contact set through its wipers to the trunk or link circuit coordinated to the finder consists in dividing the contact bank into a numbe" of groups of bank contact sets and providing the finder with. a separate set of wipers for each said group. In the finder of this type one set of wipers is always in the neighbouu hood of any particular bank contact set that is to be connected through to the trunk, or in other words, the wipers always have only to travel over a fraction of the distance that has to be covered on a tinder equipped with only one set of wipers. Special means are provided in connection with such multiple wiper switches for preventing more than one set of wipers oi? one a d the same Divided. and this application filed April 7, 1926.

finder from becoming operative simulta ncously.

The object of the present invention is to provide a switch or finder whose wipers will rapidly reach any desired set of bank con tacts in spite of their having to travel over a considerable distance before the proper set of bank contacts is reached. According to one part of my invention this is accomplished by causing the wipers to travel at a very high speed past all bank contacts that lie in the bank contact groups located between the starting point of the wipers and the bank contact set onto which the wipers are to be set, and by providing group designating contacts in the bank which, even when the wipers travel over them at a very high speed, are of such length, form, or condition that a relay or magnet connected to the hunting wiper will have time enough to act before the wiper leaves the particular group designated contact at which it is to be stopped. \Vhen the wipers have reached the proper bank contact group, their speed of travel is diminished to such an extent that the times that a wiper makes contact with each individual contact in the group of bank contact sets that it has reached will be sutlicient to enable the relay or magnet by which the individual contact sets are test-ed, to act in the desired manner.

The means in accordance with the invention by which the aforesaid object can be accomplished are various. The bank of the switch maybe divided into major and minor groups and the wipers may accordingly be made to travel at three, instead of only two different speeds. In cases in which it dc sirable to have only one type of switch in the entire system, the switches according to the invention may be used as line or trunk finders, group selectors and connectors.

In accordance with the invention a switch having a Contact bank with fixed group dcs ignating contacts and a wiper adapted to co operate with the group designating contacts is provided with means by which, after any group designating contact has been electrically marked, a continuously acting driving power is caused to move the wipers of the switeh -.v'i.thout momentary intermediate stoppages at a high speed directly to the electrically marked group, whereupon the wiper is moved at a. lower speed onto a contact in the particular group of bank contacts that correspond with the said electrically marked group designating contact. The wipers are driven over individual bank contacts at a speed which is too high to enable their stoppage to be effected by an electromagnet or electromagnetic relay con trolled by circuits closed through the individual'bank contacts, but the group designating bank contacts are long enough to enable a wiper-stopping-magnet to be energized or de-ene-rgized by the flow or interruption of current through the long contact and a wiper co-operating with the-san'ie. The movable member or rotary member which carries the wipers is moved, at a high speed against a movable mechanical step that marks the particular groups and thatis actuated by the current which flows through the group designating contact.

According to a second part of my invention a movable group designating stop is provided for each group and as soon as the high speed movement of the wipers is arrested by the stop the low speed movement of the same is caused to take place. In switches of this kind no group designating bank contacts are needed.

So far as I am aware line finders with high and low speed motion of the wipers for successive group and line selectors are entirely new and I therefore claim such finders broadly.

The wipers of my novel switch may be arranged to always rotate in the same plane and in a preferred form of a switch a shaft with a sleeve displaceable thereon used.

The wipers of the novel switch may be arranged to always move in. the same direction or they may be arranged to move at a high speed until arrested by the mechanical stop and then to rotate slowly in the opposite direction. The wipers may be moved to the desired individual set of bank contacts by imparting rotation to two co-aXia-l members in succession. The one co-axial member in the form of a sleeve may be connected to the shaft by a tensioned spring that turns the sleeve relatively to the shaft when the operation of the switch is initiated.

The switch may be arranged to be operated by only two magnets, one magnet serv ing to allow the driving force to drive the wipers at a high speed and to arrest them when thedesignated group is reached, while the second magnet serves tomove the wipers at a lower speed until the proper individual bank contact set is reached and to restore the wipers to normal.

In a modified switch three magnets are employed, viz a starting or releasing magnet for releasing the wiper carrier so as to allow the continuously acting force or spring to carry the wipers round at a high speed until they reach the designated group, a stopping magnet for stopping the wipers at the said group and a stopping and restoring magnet for first moving the wipers step by step onto the proper individual set of bank contacts and then restoring the wipers or retensioning the spring.

\Vhen the switch is used as a numerical switch a separate marking switch is associated with it which is adapted to be set by dialling impulses and to mark the desired bank contact group. This separate marking switch is unnecessary when the novel switch is used as a non-numerical switch such as a line finder.

Other features of the invention will appear hereinafter and in the drawings and claims.

The invention is illustrated in the accompanying drawing in which Fig. l is a diagrammatic side view of the novel switch.

Fig. 2 is a diagrammatic edge view of the same.

Fig. 3 is a perspective of the parts of the switch that operate its off normal contacts.

F 4- shows a cross section through the shaft ratchet and its stepping and holding pawls.

F ig.5 shows the switch in combination with circuits adapting it to be used as a line finder.

Fig. 6 shows the switch in combination group selector, and

Fig. 7 shows the switch in combination with circuits adapting it to be used as a final selector or connector.

Fig. 8 shows a side view of another modified type of switch.

Fig. 9 is a diagrammatic perspective view, and

Fig. 10 is a diagram of such of the circuits of the switch as are deemed sutiiciently elucidative to enable its operation to be understood.

Referring to Figs. 1 and 2 it will be seen that the switch has a shaft 1 on which a ratchet wheel 2 with a sleeve 3 is adapted to rotate. Fixed to the shaft 1 is a disk 4 which carries a pawl 5 adapted to engage with the teeth of the ratchet 2. A spring 6 whose one end is attached to a hub 11. of the disk at and whose other end is attached to a projection 7 011 the ratchet wheel 2, tends to rotate the ratchet wheel in the direction of the arrow, but in the normal position of the switch a detent 8 combined with the ratchet wheel abuts against a. movable stop 9 pivoted on the frame of which a piece 10 is shown in Fig. 2. In justaposition to the lower end 5 of the pawl 5 is the armature 12 of a release magnet 13 which, on being energized, swings round the pawl 5 to disengage its top end from the teeth of the ratchet wheel and to swing the hinged stop 9 out of the path of the projection 3. The ratchet wheel with its sleeve 3 and brushes 14, 15, 16, 17 is now quickly rotated by the tensioned spring 6 until the magnet 13 is deenergized and the pawl 5 is jerked by a spring 18 into the path of any one of the teeth of the ratchet wheel. lVhen the pawl 5 engages with one of these teeth a coupling is eil'ected between the ratchet wheel and the disk 4 on shaft 1. The shaft. 1 has a ratchet- 19 adapted to be rotated step by step by a pawl 29 oscillated by a rotary magnet 21. The brushes 14, 15, 16, 17 rotated with the ratchet wheel 2 wipe over a bank of contacts diagrammatically indicated in Fig. 1. The brush 14 wipes over ten long bank contacts '22, 23, 24, 25, 26, 27, 28, 29, 30, 31 each of which occupies an arc of the circle in which ten contact-s corresponding to each of the other brushes 15, 16, 17 are arranged. In Fig. 1 for the sake of convenience, only three short contacts 32, 33, 34 are shown to occupy the are of the long bank contact 26 for example. But in the telephone system described herein there are in reality ten sets of three short bank contacts such as 32, 33, 34 associated with each long bank contact so that whilst the brush 14 wipes over one long contact each of the brushes 15, 16, 17 will wipe over ten corresponding short bank contacts 32, 33, 34 etc. The long contacts together with the brush 14 control the circuit of the magnet 13 and the reason for making the contacts 22, 23 etc. long is to give the magnet 13 and the pawl 5 ample time to effect a coupling between the ratchet wheel 2 and the shaft 1 when the brush 14 meets a contact 22, 23 etc. corresponding to the group of contacts in which the trunk or line is located with which a connection is to be established.

The ratchet wheel 2 and the disk 4 have short hubs 11 and 11, Figs. 2 and A notch in each of these hubs registers with a notch in the other when the switch is in its normal position and the off normal switch will then have its contact springs in their normal position. But as soon as the release magnet 13 is energized and the hub 11 rotates with respect to the hub 11 the springs of the oil normal switch are shifted into their oil normal positions.

To restore the entire switch into its normal position impluses are sent through the magnet 21, and the pawl 20, whose forward movement is limited by the stop 20' (see Fig. 4), then rotates the ratchet 19 and the disk 4 with the pawl 5. The pawl 5 has a nose 36 at its top end which fits into rounded cavities in the indentations of the ratchet wheel and this nose 36 carries the ratchet Wheel round with it until the detent 8 of this wheel strikes against the stop 9. I The ratchet wheel will now cease rotating, but the 1 21 will (by virtue of circuit arrangenic-i 1 hereinafter described) continue rotating U shaft- 1 and the disk 4 and the pawl 5 w -l slip from tooth to tooth of the wheel 2 until it reaches the first teeth 50 and until the notches of the hubs 11 and 11 re ister with each other and the magnet 21 is deenergized by the action of the oil normal switch The spring 6 is fully retensioned during the restoration of the switch by the shaft 1 or hub 11 {to which the end of the spring is attached) being rotated whilst the ratchet wheel 2, to which the other enl of the spring 6 is attached, is held stationary by the detent 8.

In Figs. 5, 6 and 7 the brushes and magnets of the switches are denoted by the same reference numerals as in Fig. 1 except that indexes are added in Figs. 6 and 7.

In Fig. 5 a substation 100 is shown connected by wires 1 3, 104 to the bank contacts 105, 106 of the line finder LF and to corresponding bank contacts of other line liinlers assigned to the same group of subscribers. Associated with each subscril crs line is a. line relay, the line relays 101, 101 of two suliuirilieiz-i lines bcin iown in the drawing. The wires 107, 103, 109 are private normals leading to the banks of connectors as indicated in F 7.

The other details of the circuits will be readily understood from the following description of the operations which occur in establishing a connection.

It will be assumed that the calling sub station 100 desires to establish a connection vith the substation No. 123.

When the receiver at the substation 100 raised the line relay 101 is energized by current flowing the negative battery pole irom throi'igh the upper winding of the relay 101,

back co:- act 110 of the cut-off i. 102, limb 111 of the calling line, substation 100, limb 112 of the line, back contact 113 of 4 relay to earth. The line relay 101 on energizing renders the calling line busy by open ing the contact 114 connected to the private normal 109, distinguishes the substation 100 as a -alling station by closing the contact 115 and this connecting the earthed relay 102 to the wire 116, and sends a starting impulse or brush releasing impulse into a line tinder Ll by closing its contact 117, this impulse flowing from the negative battery pole through 117, 118, normal contact 119, normal contact 14 brush releasing magnet 13. to earth. The brushes 14, 15, 16, 17 will now innnediately fly or rapidly travel round until the brush 14 encounters a long contact which is disconnected from the negative battery pole, such a long contact being in the present instance the centact 120 Wlnch. 1s

disconnected from the negative battery pole by the contact 121 of the line relay 1.01 hav ing been opened.

It must be mentioned here that the substation lines multiply connected to the banks of the line finders are ordered in groups of ten each, a negative battery lead 122 being se'rially connected through contacts 121', 121 etc. of the ten line relays 101, 101 etc. to one of the ten long contacts as 120 of each finder LF belonging to the group of say one hundred subscribers served by the particular group of line finders in question.

The moment the brushes of the finder LF are released the contactspring 123 of the oft-normal switch will be raised and will. prepare the calling linehunting circuit at the contact 128. But as the line hunting brush 15 travels past its short bank contacts at a high. speed the hunting relay will, as yet, not find sulficient time to energize on any calling line. \Vhen the group hunting brush 11 encounters the long contact 120 the interval of deenergization of the brush releasing magnet 13 will be long enough to enable it to deenergize and as the movement that the coupling pawl 5, Fig. 1, has to execute in order to couple the brush carrying ratchet to the shaft is very small, the brushes will be coupled to the shaft before they have time to wipe past the entire contact 120. The group hunting brush 14 will. travel round on the long contact a certain distance before the operation of con ling the brushes to the shaft is properly e ected and to allow for this the long contact 120 may be displaced with respect to its associated groups of ten short contacts (or the brush 11 may be displaced with respect to its three mates 15, 16, 17) to such an extent that at the moment the coupling operation is properly efiected and the magnet 13 is properly deenergized the brushes 15, 16, 17 will be positioned at the first set of short bank contacts associated with the long contact 120. The coupling or primary operation of the switch being completed, the secondary operation will now be initiated by the closure of the contact 126 that results from the deenergization of the magnet 13 and completes a circuit for the stepping magnet 21 which may be traced from the negative battery pole, through back contact 127, off-normal contact 128, back contact;- 126, stepping magnet 21. interrupter 129 to'carth. The shaft of the line finder L1 with the brushes 14-, 15, 1(5, 17 is now stepped or moved. round at such a speed that the line hunting relay 125 has sufficient time to energize when the earthed line-distinguishing contact 116 of the calling line is reached by the line hunting brush 15. The relay is energized by a current flowing from the negative battery pole through 121, (Fig. 6), 125, 15, 116', 1.1.5, cut-ofi' relay 102 to earth. The relays 125 and 102 are energized simultaneously, the latter cutting oil the line relay 101 at 1.10 and 113 and. establishing a circuit for itself through its own contact 115, and the former opening the circuit of the stepping magnet 21 at 127, mintaining the calling line busy by shunting out a part of the resistance of 1.25 by means of the contact 128 and. connecting the calling line through the contacts 129, 130 to the line relay 131 of the selector, Fig. (3.

It will. be mentioned here that to prevent the startii'ig of the next line tinder in the group to which 11F belongs by the call from the substation 100, a relay may be inserted at 132 which momentarily places negative battery on the section 118 oi the starting wire at the moment this relay energizes, but which will not send another current impulse through 118, 132, 11.8 to the next line finder in the group until it is deenergized and then re-energizcd by another call. Relays of this kind are known.

lVhen the calling line is connected through to the selector, Fig. (3, as described. the line relay 131 is energized and closes its contacts 133, 13 1 while opening its contacts 135, 136. The release relay 137 immediately energized by current flowing from the negative pole through 133, 137, resistance 138 to earth. It the calling person now abandoned the call the line relay 131: would deenergize and a CllllGIlt impulse would flow' from the negative pole through 1 10, 136, the group selecting magnet 139 to earth. The group selecting magnet would shift the off normal switch 141 out of its normal position, and it would open the contact 1241-, and close the contact 145. Immediately after the release relay 137 would. deenergize on account of its being short circuited by 135. The circuit of the line lnmting relay 125 would now be open at 124 (and 1 13) so that this relay would also be de-energized. The group selecting magnet 139 during its momentary energization closes a contact 1-16 and energizes the restoring relay 147 of the line finder by a current from the negative pole through 127, 128, left winding of 1 17, 146 to earth. The restoring relay locks itself by means of a current through its right winding and the contact 1418 and impulses now flow from earth through the interrupter 129, magnet 21, contact 149, contact 128, 127, to the negative pole. These impulses continue flowing until the line finder L1 is restored to normal by the magnet 21. when the off normal switch 150 will open its contacts 128, 132 and close 119. On the opening of 128 the relay 1 17 is deenergized and the circuit of the stepping magnet 21. that restores the finder is opened. The line finder will 110w be ready for a fresh call.

The off normal switch 144 of the selector.

Fig, 6, is restored to normal by impulses flowing from the negative pole, the interrupter 141, 142, 145, magnet 139 to earth, this magnet operating a cam similar to 11, Fig. 5, or any other suitable device which restores the oil-normal switch at the proper noment.

The relay 147, after it has once been onergized with the aid of the contact 146 is made independent of the group selecting magnet- 139 during the restoration of the line finder, by its opening its own contact 157, after its contact 148 has been closed.

It will now be assumed that the calling person does not abandon the call but proceeds with the establishing of the connection by working the dial at the substation and thus causing the interruption of the line relay circuit for the purpose of selecting the desired first hundred groups. The line relay 131 is then deencrgized once and a selecting impulse flows through the group solecting magnet 139 from the negative pole through 140, 136, 139 to earth. The group selecting magnet controls the group selecting switch or indicator which consists of a rotatable ring 153, a brush 152 applying negative batteryto the ring, and contacts 154 against which the ring 153 slides. Normally the ring applies negative battery to all the contacts 154, but it has a gap at one part of its circumference as shown and this gap may be made to register with any of the contacts 154 by the ring being rotated by the magnet 139. The particular contact 154 with which the gap in the ring is made to register will correspond to the group to be selected by the selector. The contacts 154 are each connected to along contact, as 22, the function of these long contacts being similar to those of the line finder, i. e. to designate the group of bank contacts at which the brushes 14, 16, 17 shall be coupled with the shaft of the selector.

It must now be explained that during oscillations of the armature of the line relay the change-ov r relay 155 is maintained energized by current flowing from the no ive pole through 140, 155, resistance 156 to earth, but that when the said oscillations cease the change-over relay 155 is short circuited by 134 so that it lets its armature drop back to close the circuit of the brush releasing magnet 13, this circuit extending from earth through 13, 14, 165, 166, 157, 140, to the negative pole.

Since the gap in the ring 153 has been set opposite to'the first group distinguishing contact 154 the magnet 13, which would otherwise be energized by a current from earth through 13, 14, 22, 154, ring 153, wipcr 152 to the negative pole, is deenergized when the brush wipes over the first long contact 22 and hence the brushes are coupled to the shaft of the selector and are then advanced step by step by current impulses flowing from the negative pole through the inter rupter 158, contact 159 of the test-relay 160, contact 161 of the oil-normal switch 164 of the selector, contact 163 of the now (lo-energized brush releasing magnet 13, stepping magnet 21 to earth. The stepping ma net 21 new steps the shaft and brushes 14, 1.5, 16, 17 round at a slow rate in search of a tree trunk. Assuming that the trunk 200, 201, 203 is free, the test relay 160 will be energized when the test brush 15 encounters the bank contact connected to the test wire 203. The current for the test relay 160 flows from the negative pole through 160, brush. 15', test wire 203, resistance 1, contact 205 of off-normal switch 206, to earth. The test relay 160 now connects the trunk 180, 181 through contacts 132, 183 to the trunk 200, 201 and to the line relay 207 of connector, 7. At the same time the test relay 160 disconnects (at contacts 184, 185) the line relay 131 of the selector from the trunk 180, but maintains this relay 13 energized by means of the contact 186.

The line relay 207 will now be energized by current flowing through the trunks 200, 201 and 180, 181, and the line 111, 112. The release relay 208 is energized by current flowing from the negative battery pole through 209, 208, resistance 210 to earth. The release relay locks itself through its armature 211 and closes the contacts 212, 213, whilst opening the contacts 214, 215. The change-over relay 216 is short-circuited at- 217.

If the calling person now abandons the call the line relay 207 will be deenergized and after a short interval the release relay 208 will also be (leenergiz-ied in a similar manner to that explained in connection with the operation of the selector. A current impulse will be sent from the negative pole through 211, 219, 220 and through the tens selecting magnet 222 to earth, whereby the oil-normal switch will be shifted and the contact 205 opened. Immediately after the contact 213 will also be opened and hence the test relay 160 in the selector, Fig. 6, will be decnergized. The oil-normal switch 206 will be restored to normal by impulses flowing from the negative pole through the interrupter 220, contact 214, contact 221, tons magnet 222 to earth.

As a result 01 the deenergization of 131 the selector will be restored to normal by impulses fiowing from the negative pole through the interrupter 141, 142, 162, stepping magnet- 21 to earth, and by other impulses fiowing from the negative pole through 141, 145, magnet 139 to earth.

It will now be supposed that the calling person does not abandon the call but works his dial in accordance with the tens digit which is 2. The line relay 207 will then be deenergized twice and two impulses will flow from the negative pole through 211, 219, 220, tens selecting magnet 222 to earth. The tens selecting magnet sets the gap in the ring 223 opposite the second tens contact so that the second long contact 221 is disconnected from the battery. During the flow of the tens dialling impulses the changeover relay 216 is energized. by current flowing from the negative pole through 211., 216 resistance 225 to earth. But when the tens dialling impulses cease the change over relay is deenergized by its being con-- tinuously short-circuited at 217 so that the contact 218 is closed and a brush releasing impulse is sent from the negative pole through 211, 218, 227, 11 brush releasing magnet 13 to earth. The brushes 14: 15" 16 will now fly round until the brush 1 1. encounters the long contact 221 which is disconnected from battery when the said brushes will be coupled to the connector shaft in the same way as in the case of the line finder and selector. \Vhen the brushes fly round-as described the oii-normal switch 228 opens its contact 220 and closes its contacts 229, 230'. ()n the calling person now sending in the last series oi? dialling impulses, units impulses will now flow from the negative pole through 211, 219, 236, wire 231, 212, 229, stepping magnet 21" to earth. The brushes 15 16, 17 are thus stepped round to the third set of bank contacts in the second group of ten sets. The said units impulses also flow through a branch pa thin which they energize the relay 230 and prepare a test circuit at 232. When the units dialling impulses cease the change-over relay is again deenergized and a test impulse then. flows from the negative pole through 211, 218, 232, test relay 233, test brush 15 test wire 109 and then through a contact (corresponding to 11 1) on the line relay ot the wanted line and through. the cut-oil relay (corresponding to 102 of the wanted line. ()1? course, it the wanted line 18 calhng its line relay will be energized and its guarding contact will be open to prevent its being connected to by any connector. In such a case the test relay 233 will not be energized and a busy tone will be placed on the calling line, this tone emanating from the busy tone producer 239 and passing through 240, 235 to the talking circuit 201 and to the calling station. The calling person will then replace his receiver and the line relays 207, 131 will deenergize and give rise to the restoration of the switches in the manner already described.

If the wanted line is free at the moment when the test brush 15 is set onto the test wire 109 the relay'233 will be energized by a current flowing from the negative pole through 211, 218, 232, 233, 15 109 contact (similar to 114) on the line relay oi? the wanted subscriber s line, cut-off relay of the wanted subscriber to earth. The test relay 233 renders the wanted line busy by shortcircuit-ing of part of its own winding at 23st, disconnects the busy tone producer at 25. 5, connects the ringing current generator 2415 through the contacts 236, 237 to the wanted line, and closes the circuit of the interrupter rclay 2 16 at 238, this circuit extending from the negative pole through the ringing interrupter 24.7, 2 38, contact 248 of the auxiliary ltlOitSB relay 24:9, 246, to earth. The ringing currentgenerator 245 is intermittently disconnected from and the relay 250 intermittently connected to, the wanted line by the relay 216. \Vhe-n the wanted party responds transmitter feed current flows out over his line through the relay 250 which energizes and opens its contact 251 while closing its contact 252 and thus energizing the auxiliary release relay 2419 by a current flowing from earth through 252, right winding of 249 to the negative pole. The relay 240 locks itself energized by a current flowing from the negative pole; through 211, 253, left winding of 245.), to earth.

If the calling person hangs up his receiver first at the end of the conversation the restoration of the switches takes place in the manner already described. It the wanted party hangs up his receiver first the dccnergization of the relay 250 results .in the release relay 208 being short circuitcd through the closed contacts and 251. Hence the release relay 208 will deenergize and cause the restoration of the connector. The selector and line finder will also be restored when the calling party hangs up.

The scope of the invention is not limited to any particular type of switch or circuits. The fundamental feature underlying the invention is that the contact group of the switch into which the brushes or wipers are to be moved is predetermined by a contactgroup-indicating means, whereupon the wipers are moved in a single continuous etc and at a relatively high speed into the indicated group, and subsequently at a lower speed onto the desired line or trunk in the said group.

A modified type of switch in which three magnets are employed is shown in Figs. 8 to 10.

In Fig. 8 500 is a fixed or stationary shaft on. which is revolubly mounted a wheel 501 with coarse and fine teeth 502 and 503 respectively. Protruding from the wheel 501 is a sleeve 501 which carries brushes or wipers 506, 507, 508, 500 brush 506 being adapted to wipe over ten long contacts 506, 506", 506 etc. Each of the other three rows of bank contacts has ten contacts such as 509', 509 500 for each of the long contacts 506, 506", etc. A tensioned spiral sprin 510 whose ends are attached to the fixed shaft 500 and to the wheel 501 respectively tends to whirl round the wheel 501 with its brushes 506, 507, 508, 509 in the direction of the arrow but is normally prevented from doing so by a detent 511 controlled by a magnet 512. In addition to the magnet 512 the switch has a stepping magnet 513 and a stopping magnet 514 which moves a stop into the path of one of the long teeth when the brush 506 encounters a long contact 506, 506 that is connected to battery or that has had a potential applied to it which denotes that the brushes are to stopped at that particular designating contact 506, 50 The switch in y also be provided with an oil-normal switch consisting of the springs 516, 517, 518 and a. changeover switch comprising the springs 519, 520, 521.

The operation of the switch will now be more fully described with reference to the circuit diagram Fig. 10.

It will be supposed that the switch is to act as a line finder and that a subscriber calls whose line is connected to a set of bank contacts in the group of bank contacts tha corresponds to the group designating contact 506. A starting current impulse will be sent by means of the subscribers line relay (similarly as described in connection with 5) through the starting wire 5223, oilnorinal switch springs 517, 518, magnet 512 to earth. The magnet 512 is thus energized and pulls the detent out of engagement with the line teeth 503. The tensioned spring 510 then whirls the wheel 501 with the brushes 506, 507, 508, 509 round until the brush 506 encounters the long contact 506 that is connected to batter, when the magnet 5141 will be energized so as to raise the stop 515 and to bring it into the path of the third tooth 502. The third tooth 502 will strike against the end out the step 515 and swing the member 525 round on its pivot 526 so as to separate the contact springs 519, 520 and to close the contact 520, 521. The opening of the contact 519, 520 results in the deenergization of the detent magnet 512 so that the detent 511 will engage with a line tooth 503. The closure of the contact 520, 521 results in the energization of a relay 522 which attracts its armatures 526, 527. At its contact 526 the relay 522 locks itself energized and at its contact 527 the relay 522 closes a. stepping circuit which includes the interrupter 528 and the stepping magnet 513. The stepping magnet therefore receives current impulses which will continue flowing until the wipers 506, 507, 50", 509 are stepped back, i. e. are stepped round in the opposite direction to that indicated by arrow,

onto the setof bank contacts to which the calling line is connected. The moment the wipers reach the set of contacts the circuit of the magnet 513 will be opened (say at 529) by a line hunting relay in the manner described with reference to Fig. 5. The restoration of the switch to normal is accomplished by stepping round the wheel 501 with the aid of the magnet 513 until the oil-normal switch 518 drops down into the notch in the sleeve 50% as shown in Fig. 8. The wipers of the switch will then have regained their normal position and the spring 510 will then also be fully retensioned.

The brush carrier 501 could, in cert in cases, be arranged in such way that while the brushes are being whirled round to the desired group oi contacts only the group hunting brush 506 wipes over its contacts while the other brushes only commence contacting with their bank contacts after they have reached the desired contact group. Furthermore, the lengths of the group designating contacts 506, 506 etc. and the teeth could be made diil'erent so as to allow for ditl erence in the speed at which the brushes are whirled past diil'l'erent parts oi the contact bank. To increase the probabili'ly of the armature of the stopping magnet 5l-iattracted soon enough to throw the stopping pawl into the path oi the proper tooth 502, the group designating contacts 506, 506 etc. may be displaced with respect to their groups oi short contacts in such a way that the group hunting brush 506 reaches the particular group desi nating contact (506, 506 before the in c end of the stopping pawl 515 is opposite to the gap, say 502, next to the tooth, say 502 that is to strike against the stopping pawl 515.

\Vhen the switches of the novel type described herein are used line finders the section of the contact bank or the contact group to wh'eh the brushes fly under the inliuence of a spring, or to which they are moved at a high speed by a rotating shaft or the like, need not be very accurately indi cated. in the case of the switch shown in Fig. 8 for example the long contact of the particular contact group to which the brushes are to be moved and all the other long contacts beyond said long contact may be brought to the electrical condition that results in the initial motion of the brushes being stopped. Thus if the brushes are to be set onto a contact in, say, the fourth group, not on y the fourth group-indicating or long contact but also a number or all of the long contacts (the fifth, sixth, etc. long contacts) beyond it could be brought into an electrical condition that would result in the deenergination of the release magnet, so that it the stopping pawl "tails to act while the brushes are traversing the said fourth contact-group, it would act while the brushes are wiping past the filth group. After the stopping pawl has acted the brushes would then be moved at a lower speed over contacts of the fifth contact-group and then over contacts in the fourth group until the proper contact set is ultimately reached.

I claim 1. In a switch, a contact bank having fixed individual contacts divided into groups and group designating contacts, a wiper adapted to cooperate with said group designating contacts, a power means for driving said wiper without intermediate stoppages up to any designated group, a toothed member that travels with said wiper, a stopping member that engages said toothed member to stop the brush when it reaches the des gnated group, an electromagnet for operating sair stopping member, and means for movingthe brush to an individual contact in the designat d group atter it has been stopped by the engagement of said stopping member by said toothed member.

2. In a switch, a contact bank having fixed individual contacts divided into groups and group designating contacts, a wiper adapted to cooperate 'ith said group designating contacts, a spring for driving said wiper without intermediate stoppages up to an; dcs'gnated group, a toothed member that travels with said wiper, a stopping member that engages said toothed member to stop the brush when it reaches the designated group, an elcctromagi'iet for operating said stopping member, and means for moving the brush to an individual contact in the designated group after it has been stopped by the engagement of said stopping member by said toothed member.

3, In a switch, a contact bank comprising groups individual. contacts and a group designating contact of the length ot a plurality of individual contacts, wipers ad apted to travel over said contacts, means controlled by a calling station for electrically marking any said group designating contact, and a wiper stopping magnet tor arresting the wipers when they reach the electrically marked group of bank contacts.

4. In a high speed and low speed switch, a contact bank comprising groups of individual contacts and a group designating con tact for each group adapted. to be electrically marked under control of a calling station, wipers that travel over said contacts, a Wiper stopping magnet, an electric circuit that extends through said magnet and said designating contacts, a wiper stopping means operated by said magnet to stop the high speed motion of the wipers in response to a change of current in said electric circuit during the travel of the wipers, and means for subsequently operating the wipers at a lower speed of travel.

5. In a multi-position switch, bank contacts divided into groups adapted to be electrically marked under control of a calling station, wipers that travel over said. bank contacts, a positively acting member that positively stops the wipers at the proper contact group, and a magnet for operating said member that is energized by a current thattlows through a said wiper and a bank contact that is approximately as long as a plurality ot individual bank contacts of a said. contact group.

6. In a switch, a contact bank having fixed individual contacts divided into groups and group designating contacts, a rotating wiper adapted to cooperate with said group (it 'ignating contacts, a power n ans for driving said wiper without intermediate stoppages up to any designated group, a toothed member that travels with said wiper, a stopping member that engages said tootacd member to stop the brush when it reaches the designated group, an electroniagnet tor operating said stopping member, and means for moving the brush to an individual contact in the designated group atter it has been stopped by the engagement ct said stopping member by said toothed in en ibe r.

7.111 a switch, a contact bank having fixed individual contacts divided into groups and group designating coi'itacts, a rctating wiper adapted to cooperate with said group designating cinitauits, a spring for driving said wiper without interim-(Hate stoppages up to any designated group, a toothed. member that travels with said wiper, a stopping member that. engages said toothed member to stop the brush when it reaches the designated group, an electromagnet for operating said stopping member, and means for moving the brush to an individual contact in the designated group atter it has been stopped by the engagement of said stopping member by said toothed member.

8. In a switch, a contact bank comprising groups oi individual contacts and a group desigi'iating contact of the, length of a plurality of individual contacts for each. group, rotating wipers adapted to travel over said contacts, means controlled by a calling subscriber for electrically marking any said group designating contact, and a wiper stopping magnet tor arresting the wipers when they reach the electrically marked group of bank contacts.

9. In a high speed and low speed switch, a contact bank comprising groups of individual contacts and :1V group designating contact "for each group, rotating wipers that travel over said contacts, a wiper stopping magnet, an. electric circuit that extends through said magnet and said designating contacts, a wiper stopping means operated by said magnet to stop the high speed 1110- tion of the wipers in response to a change of current in said electric circuit during the travel of wipers, and means for subsequently operating the wipers at a lower speed of travel.

10. In a multi-position switch, bank con tacts divided into groups adapted to be electrically marked under control of a calling station,rotating wipers that travel over said bank contacts, a positively acting member that positively stops the wipers at the proper contact group, and a magnet for operating said member that is energized by a current that flowsthrough a said wiper and a bank contact that is approximately as long as a plurality of individual bank contacts of a said contact group.

11. A switch comprising bank contact groups, calling telephone lines connected to said contacts, wipers, means for moving said wipers over a plurality of said bank contact groups ata high speed, a positively acting stopping device for stopping the wipers at the desired bank contact group, and means for subsequently operating the wipcrsat a lower speed of travel.

12. A switch with bank contacts arranged in groups, calling telephone lines connected to said contacts, means controlled by a calling line for designating a particular group of contacts, wipers that travel over said contacts, means for driving the wipers in continuous motion to the neighbourhood of an individual contact, and means for subsequently driving the wipers more slowly to said individual contact.

13. A switch with bank contacts, wipers, calling telephone lines, relays associated wit-h said lines for applying marking potential. to individual bank contacts and group designating contacts, means for driving said wipers at a high speed to a position marked by a group designating contact and subsequently at a lower speed to a position marked by an individual bank contact.

14. A switch with bank contacts, wipers, calling telephone lines, relays associated with said lines for applying marking potential to individual bank contacts and group designating contacts, means for driving said wipers at a high speed to a position marked by a group designating contact and subsequently step by step at a lower speed to a position marked by an individual bank contact.

15. In a hunting switch, individual bank contactsdivided intogroups, group designating bank contacts of the length of a plurality of individual contacts adapted to be electrically marked under control of a calling station, wipers driven by a continuously acting force at a high speed to a bank con- I tact group electrically marked by a said 16. In a switch, bank contacts divided into groups, group designating contacts of the l ngth of a plurality of bank contacts and adapted to be selectively marked under the controlof a calling subscriber, wipers, means for driving said wipers in a continuous motion at a high speed over said contacts, group testing means for rendering said driving means inoperative when the wipers reach a designated group, and testing means for testing lines individually to stop the wipers on an individual set of bank contacts.

17. In a switch, bank contacts, calling telephone lines connected to said contacts, rotary wipers adapted to travel over said contacts, spring motor means for driving the wipers in continuous motion, to the neighbourhood of an individual contact, and stepby-step means for subsequently driving the wipers step by step to said individual contact.

18. In combination with a switch, bank contacts, rotary wipers, calling telephone lines, relays associated with said lines for applying marking potential to individual bank contacts and group designating contacts, power storing means for driving said wipers at a high speed to a position marked by a group designating contact and means subsequently effective to drive said wipers step by step at a lower speed to a. position marked by an individual bank contact.

19. In a hunting switch, individual bank contacts divided into groups, group desig nating bank contacts adapted to be elect-rically marked by a calling station, rotary wipers driven by a power storing means at a high speed to a bank contact group electrically marked by a said group designating contact, and means for driving the wipers at a lower speed after they have stopped at the designated group.

20. In a switch, bank contacts divided into groups adapted to be electrically marked by a calling station, rotary wipers, a spring motor for driving said wipers in a continuous motion at ahigh speed over said contacts, group testing means for rendering said driving means inoperative when the wipers reach a designated group, and testing means for testing lines individually to stop the wipers on an individual set of bank contacts.

21. A line finder comprising bank con tacts, wipers, a spring for driving the wipers, and an olectromagnetically controlled armature for positively stopping the wipers at a desired position in the contact bank.

22. A line finder comprising bank contacts, rotary wipers, a spring for driving the wipers, and an electromagnetica]ly controlled armature for positively stopping the wipers at a desired position in the contact bank.

I A. switch comprising bank contacts lira.

nto groups each group adapted to be electri-ally marked under control of a calling station, wipers, power storing means for driving said wipers in a continuous motion at a high speed over said contact-s, wiper controlling means for rendering said driving means inoperative when the wipers reach a desired bank contact group, and test-- ing means for testing bank contacts individually after the wipers have reached the desired group.

24. In a. telephone system, non-numerical switches, nui'nerical switches, all of said; switches adapted to execute separate group and individual line selecting movements, means controlled by a calling'subscriber for marking a desired group and a desired line in the desired group at certain of said switches, power storing means for each switch for effecting the group movement-s thereof and. separate intermittent, power mechanism for each switch. for executing the line selecting movements thereof.

25. In a telephone system, calling lines, numerical switches adapted to execute separate group-and line selecting movements, spring motive means adapted to execute the group selective movements of the switches, automatic impulsing mechanism for executing the line selecting movements of the switches, and wiper controlling means operated by currents that flow over the two wires of a calling line in series. I

26. In a telephone system, calling lines, wanted lines, and numerical selectors for selecting wanted lines, said selectors comprising bank contacts divided onto groups and connected to said wanted lines, wipers, a continuously operative power means for driving said wipers into a desired bank contact group, wiper controlling means operated from a said calling line by electric currents flowing over two wires of the line in series and adapted to determine the amount of travel imparted to the wipers by said continuously operative power means, and means for moving the wipers step by step with the aid of said wiper controlling means after the wipers have been driven onto a desired group. 1

27. In' a telephone system, trunks,'group selectors provided with wipers for selecting.

groups of wanted trunks and a tree trunk in a group, a continuously operatiw e power means for driving said wipers onto a desired group of trunks, wiper controlling means operated from a said calling line by electric currents flowing over two wires of the calling l ne 1n series and adapted to determine the amount of travel imparted to the wipers by said continuously operative power means, and means for subsequently moving the wipers step by step until they reach a free trunk.

28. In a telephone system, calling lines, wanted lines, and numerical selectors for selecting wanted lines, said selectors comprising bank contact-s divided into groups and connected to said wanted lines, wipers, a spring for driving said wipers onto a desired bank contact group, wiper controlling means operated from a said calling line by electric currentsfiowing over two wires of the line in series and adapted to determine the amount of travel imparted to the wipers by said spring, and means for moving the wipers step by step with the aid of said wiper controlling means after the wipers have been driven onto a desired group.

29. In a telephone system, trunks, group selectors comprising wipers for selecting groups of wanted trunks and a tree trunk in a group, a spring for driving said wipers onto a desired group of trunks, wiper controlling means operated from a said calling line by electric currents flowing over two wires of the calling line in series and adapted to determine the amount of travel imparted to the wipers by said spring, and means for subsequently moving the wipers step by step until they have reached a free trunk.

30. In a switch, a sleeve and shaft interconnected by a spring that turns the sleeve relatively to the shaft where the operation of the switch is initiated, bank contacts divided into groups, wipers that travel over said contacts, a magnet for releasing the sleeve so that the spring may rotate it until a group hunting wiper reaches a said group, and another magnet that moves the wipers step by step until the proper individual bank contact is reached.

31. In a switch, bank contacts divided into groups, wipers that travel over said bank contacts, a spring for driving said wipers, means for retensioning said s ring after each use of the switch, a magnet or stoppin the spring driven wipers at the proper Iiank contact group, and a stepping magnet for stepping the wipers onto the proper individual bank contact in the group.

32. In a switch, bank contacts divided into groups, group designating bank contacts, spring driven wipers that travel over said contacts, a numerical group designating switch for marking the proper group designating bank contact, and means for subsequently causing the wipers to hunt for a free trunk connected to a said group of bank contacts.

33. In a rotary one-motion switch, bank contacts divided into groups, wipers that travel over said bank contacts, a spring for driving said wipers, means for retensioning said spring after each use of the switch, a. magnet for stopping the spring driven wipers at the proper bank contact group, and a stepping magnet for stepping the wipers onto the proper individual bank con- .t-act'in the group.

34. In a rotary one-motion switch, bank contacts divided into groups, group designating bank contacts, spring driven wipers that travel over said contacts, a numerical group designating switch for marking the proper group designating bank contact, and means for subsequently causing the wipers to hunt for a tree trunk connected to asaid group of bank contacts.

35. In a telephone system, non-numerical switches, numerical switches, the numerical switches adapted to execute under control of a calling station separate group and line selecting movements, spring power means for effecting the group selective movement of each of said switches, and means for storing power in the spring upon the restoration of the associated switch.

36. In a telephone system, non-numerical switches, numerical switches, each of said switches having circuit closing wipers and co-operating bank contacts and means for moving the wipers of any switch onto the desired set of bank contacts by imparting rotation to two coaxial members in succes- SlOIl.

37. In a line finder, a single arcuate level of bank contact sets, wipers, means for driving the wipers over said bank contact set-s first in a continuous high speed motion and then at a lower speed in a step-by-step movement.

38.111 a telephone system, calling and called lines, calling line finders and numerical switches adapted to execute group and line selecting movements under control of numerical impulses for connecting any calling line to any called line, and spring driven wipers in all said finders and switches.

39. In a telephone system, calling and called lines, switches adapted to execute group and line selecting movements under control of numerical impulses for interconnecting any two of said lines, wipers, springs in all said switches for moving said wipers,

FRITZ ALDEND ORFF.

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