US1540059A - Selective switch - Google Patents

Description

June 21, 1,540,059 1 R. D. CONWAY SELECTIVE SWITCH Original Filed Dec. 5, 1921 3 Sheets-Sheet l June 1925. 1,540,059 R. 0. CONWAY SELECTIVE SWITCH Original Filed Dec. 5, 1921 3 Sheets-Sheet 2 Patented June 2, 1925.

I UNITED STATES PATENT oFFicE.

MY ID. CONWAY, OF BERNARDSVILLE, NEW JEMEY, "ASSIGNOR TO WESTERN ELEC TRIC COMPANY, INCORPORATED, OF NEW- YORK, N. Y., A CORPORATION OF SELECTIVE SWITCH.

Original application filed nu bers,

To all whom it may concern."

Be it known that I, ROY D. CONWAY, a citizen of the United States, residing at Bernardsville, in the county of. Somerset, State of New Jersey, have invented certain new and useful Improvements in Selective Switches, of'which the following is a full, clear, concise, and exact description. This invention relates to selective switches and particularlv, to cross-bar switches used for the selection and connection of'balancing networks in repeating circuits, and is a division of application Serial No 519,864, filed December 5, 1921, by Roy D. Conway.

The object of the invention] is to provide an efficient, simple and. rugged switching means which will establish connections in both, its normal and operated positions.

A. feature of the invention is the use of back contacts for the flexible contact fingers of a cross bar switch whereby such fin- J. N. Reynolds 1,238,194, August 28, 191.7,.

entitled Automatic switch? This, switch comprises vertical bars such as 1 shown in Fig. 4 and shown diagrammatically 1n Flg, 3, and comprises horizontal bars such as 2 shownin Fig, 4 and shown diagrammatically For reasons which willbe made in Fig. 3. apparent hereinafter, 'thevertical' bars may with propriety be hereinafter termed cord bars andthe horizontal bars may appropriately be hereinafter termed I net bars. Each ofthese vertical bars comprises a plurality of Vertical metallic strip conducting members havingprojeeting spring contacts such as those designated 3 in Fig. 4, and

each of the horizontal bars compriseshorizontal metallic strip conducting members having contact projectionssuch as those designated 4in 4. The vertical bars are 1921, Ser al N 5,1 ,864.. Divided and this application filed October 15, 1923., Serial No. 668,732.

mounted'in the frame (not shown) of the.

cross-bar switch by means of vertical pivots such as Each horizontal bar 2 is supported from theframe (not shown) of the cross-bar switch by means of" members 6, rigidly attached to the frame, .and link 7. The link 7 is pivoted to members 6 by pin 8 and to bar 2 by pin 9. The spring 10 normally presses the bar 2' lengthwise toward the right as viewed in Fig. 4, but the bar 2 may be moved lengthwise toward the left as viewed in Fig. 4 by armature 11 of electromagnet 12 when the electromagnet is energized. This armature is in the form of a bell crank lever pivoted at 13 in the frame of the cross-bar switch and bearing against the pin 9. A spring 14 normally biases the bar 1 in a counter clockwise direction as viewed from above in Fig. 4. Upon the en ergization of the electromagnet 15, the armature 16 thereof overcomes the biasing action of spring 14. The armature 16 is mounted in the frame of the cross-bar switch by a pivot 17.

In the operation of the switch, magnet 15 turns bar 1 clockwise to position spring contacts 3' for subsequent engagement of their ends by contact projections 4, and magnet 12 moves bar '2 lengthwise to engage contact projections4 with that set of contacts 3 located at the intersection of bars 1 and 2. Upon the deenergization of magnet 15, spring 14 turns bar 1 counterclockwise looking down upon Fig. 4, to restore bar 1 to a positionin which the ends of all of its sets of contacts 3 except the engaged set are out of the line of movement of contacts such as 4. p

Bar 1 carries a strip 18 of insulating material in which are mounted conducting plates 19 for bridging across contacts 3. lVhen contacts 4 engage spring contacts 3, the latter are moved out of engagement with plates 19. The purpose of providing bridging plates 19., and the manner in which magnets 1'5 and 12 are energized will be made apparent hereinafter.

' The magnets, such. as 15, which actuate the vertical or cord bars may be termed cord bar magnets, and the magets, such as 12, which control the horizontal or net bars may be termed net bar magnets. It will be explained below that each of the net bar magnets comprises twomagnets, a net bar pick-up magnet and a net bar locking magnet.

In the diagrammatic showing of the crossbar switch in Fig. 3, the net bars are designated 2, 2, 2 2 2 etc., reading from the top of the figure to the bottom of the figure, and the cord bars are designated 1, 1, 1', 1, reading from right to left. In Fig. 3, the spring contacts of cord bar 1, generally considered, are designated 3, those of cord bar 1 generally considered, being designated 3 those of cord bar 1", enerally considered, being designated 3*, etc. Certain ones of these spring contacts are, for convenience, designated by various reference characters individual to the spring contacts to which they are applied. The contact projections of net bar 2, generally considered, are designated 4, those of net bar 2 generally considered, being designated 4", those of net bar 2, generally considered, being designated 4, etc. Certain ones of these contact projections are. for convenience, designated by various reference characters individual to the contact. projection to which they are applied.

Referring to Fig. 1, repeaters such as R and R, which may be of any suitable type such as the wellknown vacuum tube repeaters, are employed to interconnect lines such as L L L, and L,. Referring to Fig. 3, networks for balancing these lines are shown at 21, 22, 23, 24, 25, 26 and 27. Networks 21, 22 and 23 may be building out sections or may be balancing sets for composite or phantom apparatus. Networks 24 and 25 may be building out sections or may be basic networks. Networks 26 and 27 may be for instance, basic networks having impedances different from those of networks 24 and 25. As appears from Fig. 3, each of the net bars of the cross-bar switch has connected thereto one of the networks 21 to 27. It will be understood, of course, that the drawing does not show all the cord bars or net bars and networks which may be included in a single cross-bar switch.

The operation of the system in selecting suitable balancing networks and connecting them to the lines L, and L, will now be described, on the supposition that the operator inserts plugs P and P into the jacks of lines L and L, to connect these lines through repeater R. Upon the insertion of plug P in the jack of line L,,, magnet 30 is energized by current flowing in the circuit from ground through battery 31, resistance 32, magnet 30, lead 33, sleeve conductors of plug P and the cooperating jack, lead 34 and winding of magnet 35 back to ground. Magnet 30 attracts its armature, but the closing of this contact does not complete any circuit. Magnet 35 does not attract its armatures at this time, because the resistance 32 reduces the current flow from battery 31. Upon the in sertion of plug P into the jack of line L,, magnet 36 is energized over the following circuit: from ground through battery 37, resistance 38, winding of magnet 36, lead 39, sleeve conductors of plug P and the cooperating jack, lead 40, winding of magnet 41 back to ground. Magnet 41 does not attract its armatures at this time, because the resistance 38 reduces the current flow from battery 37. The magnet 36 attracts its armature closing a circuit for magnet 42 as follows: from ground through battery 43, armature 44 of magnet 45, lead 46, lead 47, contact spring 48 of magnet 49, lead 50, armature 51 of magnet 36, lead 52, armature of magnet 30, lead 54, contact spring 55 of magnet 56, lead 57, winding of magnet 42, lead 58, lead 59, armature of magnet 61 and lead 62 to ground. Each of the magnets 45, 42 and 61 is individual to a repeater cord circuit, magnets 45 and 61 being operated in the same fashion as magnet 42. Only one of these magnets can be in the operated condition at any given time, as will be readily apparent from the arrangement of the armatures of these magnets in the battery lead 46 and ground leads 59 and 62 as shown in the drawing. There will of course be one magnet such as the magnet 45, 42 and 61 for each repeater cord circuit. It will be made apparent hereinafter that since only one of the magnets can be in the operated condition at any given time the operation of selecting balancing networks and connecting them to a repeater can take place for only one repeater at a time. Thus, magnets such as 45, 42 and 61 insure that the network selecting and connecting operation for one repeater will be finished before such operation can begin for another repeater.

\Vhen magnet 42 has been energized as mentioned above, it att acts its armatures 63, 64 and 65 causing line selection control relay 41 to attract its armatures 94, 104 and 113. This operation of magnet 41 is due to the energization of this magnet over the following circuit: from ground through battery 43, armature 44, lead 46, armature 64, lead 66, lead 67, armature 68 of retarded relay 69, lead 70, armature 63, lead 71, winding of magnet 36, lead 39, sleeve conductors of plug P and the cooperating jack, lead 40 and winding of magnet 41 to ground.

The attraction of armature 64 of relay 42 as mentioned above also causes the cord bar magnet 15", which is like the cord bar magnet 15, shown in Figs. 3 and 4, to attract its armatures 16, 72 and 73, the circuit for energizing this cord bar magnet 15 being as follows: from ground through battery 43, armature 44, lead 46, armature 64, lead 66, lead 67, lead 74, lead 75, armature 76 of retarded relay 49,1ead 77, lead 78, contact springs 283, 284 and 285 cross bar winding of magnet 15".to ground. The attraction oi the armature 16 by cord bar magnet 15*, causes the cord bar 1 to turn on its pivots to positionits spring contacts 3 for subsequent engagei'nent of their ends by contacts ofa net bar in the fashion described above in connection with Fig. 4;. i The attraction of arn'n ture 73 by magnet 15", and the attraction of armature 94 of line selection control relay 41, both as men tioned above, causes the operation of mag nets 79 and over the following circuit: from ground through battery 43, armature 44, lead 46, armature 64, lead 66, leads 67, 74 and 75, armature 76, leads 77 and 81, winding of magnet 79, lead 82, armature 73, lead 83, lead 84, lead 85,.armature 86, contact spring 87, winding ofnet bar pick-up magnet80, lead 88, contact spring 89, armature 90, lead 91, lead 92, lead 93., and armatures 94 of line, selection control relay 41 to ground. The net bar pickup magnet winding 80 forms part of the net bar magnet 12, shown in Fig. 4 and also in Fig. 3, each net barmagnet' comprising in addition to a pick-up magnet winding, a locking magnet winding such as is shown at 114 in Fig. 3. Upon the energizati-on oi the pickup magnet winding 80 of magnet 12, as just mentioned, the netbar 2 is moved longitudinally toward thjeleft to. engage contact projections 159, 119, etc., with contact springs 158, 118, etc., (these projections and springs being located at the intersection of bars 2 and 1*), all in the general fashion described above in connection with Fig. 4.

- The attraction of armature 73 by cord bar mag-net 15 and: the attraction ofv armature 104by line select-ion control relay 41, both as mentioned above, causes the operation of net bar pick-up magnet 95, the energizing circuit for this magnet being from battery 43 to lead 84 as just traced and thence through lead 96, armature 97, contact spring 98, winding of magnet95, contact spring 199, armature 100, lead 101, lead 102,.lea'd103, armature 1 04 toground. Thereupon the net bar 2 is moved to engage contact projections 17 3, 125, etc.. with contact springs 17 2, 124, etc.

The attraction of. armature 7310f] magnet 15 andtheattraotion ofarmature 113 of line selection control relay 41, both as mentioned above, cause the operation'of'net bar pick-up magnet 105, the energizing circuit for this magnet being from battery 48 to.

lead 84 as traced above and thence through lead 106, armature 107, contact spring 108,

upon the net; bar 2? is. inoved'to engage contact projections 186, 131, etc, with contact springs 185, 130, etc.

The energization oil not bar pickup magnet winding 80, as mentioned above, causes the attraction of its armatures 86, and 161. The armatures 86 and 90 each break the original energizing circuit, or piclz up circuit, which passed through windings off iagnets 79 and 80. However, before such circuit is broken, armature 86 allows contact spring 87 to contact with a terminal of the coil of magnet 114, and armature 90 allows contact spring 89 to contact with lead 122, and moreover, contact 119 has engaged contact 118, as mentioned above; and, therefore, a locking circuit, including the wind.- ing of pick-up magnet 80 and the winding of locking magnet 114 in series, is closed for net bar magnet 12, this locking circuit being as follows: from ground tl'irougli battery. 48, armature 44, lead 46, arn'iature 64, leads 66, 67 and 74, armature of magnet 79, leads 115 and 116, cord bar conducting member. 117, cord bar contact 118, net bar contact 119, net bar conducting member 126, lead121, winding of net bar locking magnet 114, armature 87, winding of net bar pick-up magnet 80, lead 88, armature 89, lead 122 to ground. As soon as armature 86 has. become disengaged from contact spring 87 (and armatures 97 and 107 have similarly and sii'nultaneously disengaged contacts 98 and 108, due to the energization, as mentioned above, of magnets and 1.05), magnet 7 9 is deenergized and therefore the circuit justtraced from lead 74 to lead 116 is broken at the armature of ma net 7 9' but b 7 a locking circuit for not bar magnet 12 is maintained, for a circuit from lead 74 to lead 116 is maintained through. the follow ing path between lead 74 and lead 116: from lead 74 through lead 75 and resistance 135 to lead 116. Moreover, a new circuit between lead 74 and lead 116 is established through the back contact of the armature of magnet 7 9 and the winding of magnet 69.

The energization of net bar pick-up magnet 95, as mentioned above,- results in the establishing of a locking circuit for magnets 95 and 123 just as, in the manner described above, the energization of net barpiclcup magnet 80 resultsin the establishing of. a locking circuit for magnetsSO and 114. The locking circuit t or magnets 95 and 123 is as follows: from battery 43 to cord bar conducting member 117, as in the caseof the locking circuit for magnets 80 and 114, thence through cord bar contact spring 124, net bar contact projection 125, net bar conducting member 126, lead 127, winding of magnet 123, contact spring 98, winding of magnet 95, contact spring 99, lead 128, to ground.

Theienergization of net bar pick-up magnet 105, as mentioned above, results in the establishing of a locking circuit for magnets 105 and 129 just as, in the manner described above, the energization of net bar pick-up magnet 80 results in the establishing of a locking circuit for magnets 80 and 114. Th locking circuit for magnets 105 and 129 is as follows: from battery 43 to cord bar conducting member 117, as in the case of the locking circuit for magnets 80 and 114, thence through cord bar contact spring 130, netbar contact projection 131, net bar conducting member 132, lead 133, winding of magnet 129, contact spring 108, winding of magnet 105, contact spring 109, lead 134 to ground.

As has been mentioned above, the energization of net bar pick-up magnets 80, 95 and 105, causes the deenergization of magnet 7 9 by opening branches of the circuit for magnet 79 at armature 86 and contact 87, armature 97 and contact 98, and armature 107 and contact 108, and the armature of magnet '79 then closes a circuit through the coil of magnet 69. Slow operating magnet 69 then attracts its armature 68 thus breaking the circuit traced above through battery 43 to marginal relay 41 and causing relay 41 to release its armatures, resistance 38 preventing the current fr'om battery 37 through winding of relay 41 from being suflicient to maintain relay 41 operated. If magnet 69 were not slow operating, then upon the enen gizat'ion of winding 80 and the consequent closing of contacts 118 and 119 and engagement of contact spring 87 with one terminal of magnet 114 (all as described above) mag net 69 might possibly receive current through the armature of magnet 79 before the latter armature left its back contact, and therefore the armature of magnet 69 might possibly be picked up before magnet 79 had picked up and released.

The attraction of armature 68 as mentioned above also closes the energizing circuit for slow operating relay 49 as follows: from ground through battery 43, armature 44, lead 46, armature 64, lead 66, lead 67, armature 68 and winding of magnet 49 to ground.

The energization of relay 49 attracts its armature 76 thereby opening the circuit traced above from battery 43 to lead 77. This opens the circuit traced above through winding of cord bar magnet 15, whereupon a spring (not shown) corresponding to spring 14 of Fig. 4, returns the cord bar 1" to its normal position, but the sets of spring contacts 3 which have been engaged by contacts 4, 4 and 4 of the net bars 2, 2 and 2 remain in such engagement.

Th energization of magnet 49 as mentioned above opens the circuit traced above from battery 43 through winding of magnet 42 at contact spring 48, but closes a circuit for magnet 42 from battery 136 through armature 137, contact spring 48, lead 50, armature 51, lead 52, armature 53, lead 54, contact spring 55, lead 57, winding of magnet 42, lead 58, lead 59, armature 60, lead 62 to ground.

The attraction of armature '76 of relay 49 as mentioned above also causes the operation of marginal line selection control relay 35, the operating circuit for relay 35 being as follows: from ground through battery 43, armature 44, lead 46, armature 64, lead 66, lead 67, lead 74, lead 75, armature 76, lead 137, armature 138 of retarded relay 139, lead 140, winding of magnet 30, lead 33, sleeve conductors of plug P and the cooperating jack, lead 34, lead 35 to ground. The purpose in having magnet 49 slow operating is to delay the closing of the contacts of line selection control relay 35 until after the contacts of line selection control relay 41 are open.

The operation of relay 49 as mentioned above and the consequent attraction of its armatures 7 6 and 142 also causes the operation of cord bar magnet 15 over the following circuit: from ground through battery 43, armature 44, lead 46, armature 64, leads 66, 67, 74, 75, armature 76, armature 142, lead 144, armature 145 of relay 56, lead 146, lead 147, winding of magnet 15 to ground. Magnet 15 thereupon operates its cord bar 1 and also its armatures 148 and 149.

The function of armature 148 will be made apparent hereinafter.

The attraction of armature 149 and the closing of the contacts of line selection control relay 35 cause the energization of magnet 150 and net bar pick-up magnet 151 over the following circuit: from ground through battery 43, armature 44, lead 46, armature 64, leads 66, 67, 74, 7 5, armatures 76 and 142, lead 144, armature 145, lead 146, lead 152, winding of magnet 150, lead 153, armature 149, lead 154, lead 84, lead 155, armature 141, lead 156, conducting member 157 of cord bar 15, spring contact 158, contact projection 159, lead 160, armature 161, lead 162, armature 163, contact spring 164, Wind ing of pick-up magnet 151 of net bar 2, lead 165, contact spring 166, armatures 167 and 90, lead 91, lead 168, lead 169, and armature 170 of line selection control relay 35 to ground.

The attraction of armature 149 by cord bar magnet 15 and the closing of the contacts of line selection control relay 35 as mentioned above also cause the energization of net bar pick-up magnet 171 over the following circuit: from battery 43 to conducting member 157 of the cord bar 1, as just traced, thence through spring contact 172, contact 173, conducting member 174,

' lead 1.7 5, armatnre's 176 and 177, contact spring 178, winding of net bar pickup magnet 171, cont-act spring 179, armatures 180 and 100, leads 101, 181, and 182,'armature 1'83 toground. I I v The attraction of armature 149 by cord bar magnet 15 and the closing of the con tacts of line selection control relay 35, as mentioned above, also 'cause; the energiza tion ofnet bar pick-up magnet 1840ver the following circuit: from battery 43 to cord bar conducting member 157, as traced above, and thence through spring contact 95, contact projection 186, netbar conducting member 187, lead 188, a'r 'nat'ures 189 and 190, contact sprin 191, Winding of net bar pick up niagnetl 4, contact sprin'g 192, arma; tnres 193 a11d 110,1'e'ads 111, 194 and195', armature 196' to ground. 1 v Upon the fenergizatioir of net bar pickup magnet 151', as mentioned above, net bar 2 is moved to the left; as viewed in 3 to engage a set of it's contact projections with a set of spring contacts'on the cord bar 1, which is now being held in operated position by corn bar magnet Similarl upon the energization of magnets 171 and 184, as mentioned above,*the net bars 2 and 2 corresponding to these magnets respectively are moved to the left as viewed in Fig.3 and a set of contact projections on each of these bars engagesja set ofspring contacts on'the cord bar 1. a

The energization of magnet 150-, and the energization of pick-up magnet 151 andthe 'consequentoperation of net bar 2?,all as mentioned above, cause the 'energiiation of net bar locking magnet 197 over 'the'following circuit: from battery 44, lead 46, armature 64, lead 66, lead 67 ,lead 74, lead 75, armature 76, armature 142, lead'14'4, lead 198 armature of magnet 150, lead 199, lead 200, cord bar conductingmember 201, spring contact 202, contact 203,net bar conducting member 204, lead 205,"Winding of magnet 197, armature 164, winding of ma net 151, armature 166' and 205 to ground. imilarly the energizatioi'i of magnet 150', and the energi zation of pick-up magnet 171 and the consequent operation of net bar 2, all as mentioned above, cause the energi'zation of netbar locking magnet 206 overthe following circuit from battery 43'to cord bar con-v ducting member 201-, asjust traced, and thence through spring contact 207, contact 208,net bar conducting member 209, lead 210, winding of magnet 206, armature 178, winding of magnet 171, armature 17 9, and

1 lead 211 to ground; Similarly the energize tion of magnet 150 and the energization of pick-up magnet 184 and the consequent operation of net bar 2','fall as mentioned above,

' cause the energi'zation-off net bar locking 1mignet212 over thejfollowing circuit from battery 43" to cord bar conductlng member 201, as traced above, and thence through spring contact 213, net bar-contact 214, net bar conducting member 215', lead 216, Wind ing of magnet 212, armature 191, winding of magnet 184, arn' ature192, and lead 217 to ground. That part of the circuits traced above for locking magnets197, 206 and 212 which comprises, lead 198, armature of magnet 150 and lead 199 is shunted by a resistance 218.

The operation of the pick-up magnet 151, as mentioned above, attracts the armature 163 of the magnet, thereby breaking the initial operating circuit of the magnet at armature 163. Similarly, theoperation of magnets 171 and 184 break the initial operating circuits of these magnets at armature 177 and 190, respectively. The breaking of all of these branches of the circuit through magnet 150 causes that magnet to release its armature thereby opening the contactbetween the armature and lead 199 and connecting winding of retarded relay 139- (instead of lead 199) in parallel with resist; ance 218 in a circuit supplying current to the locking magnets 197, 206 and 212. Magnet 139' thereupon attracts its armature 138 andthus causes the breaking of the circuit traced above from battery 43 through Winding of marginal line selection control relay and thereby causes line selection control relay 35 to' release its armatures. The purpose in making magnet 139 slow operating is to' insure that this magnet will not be operated before magnet 150 has picked up i and released.

The operation of relay 139, as mentioned above, also closes the following energizing circuit for relay 56: from ground through battery 43, armature 44', lead 46, armature 64, leads 66, 67, '74, 75, armature '76, lead 137, armature 138, leads 219 and Winding of niaigi'iet 56 to ground.

Relay 56 then attracts its armature 156 thereby opening the circuit traced above for cord bar magnet 15 The cord bar ,1 re;- turns to its normal position. However, the sets of spring contacts this cord bar which are in engagement with net bar contacts at the time magnet 15 is deenergized, remain such engagement. t v The-energization of rel-(13 56, as mentioned aboye, attracts armature 220 of the relay Cir thereby breaking the circuit of Winding of magnet 42 at contact 55, thus causing,the bi' eaking at 64 of the connection traced above from battery 43 to lead 67. However, before thisbreakat 64 occurs, armature 220 by engaging spring contact 55 connects battery 136 (I magnets 139 a d; 56, and the pic-leap locking magnets of net bars 2 2 and 2 are maintained energized from battery 136 until the circuit traced above from battery 136 to lead 67 is broken at armature 51 or 53 by the deenergization of magnet 36 or 30, due to the removal of plug P or P.

The breaking of the circuit of magnet 42, as mentioned above, releases its armatures 64 and 65, whereupon the magnets such as 45 and 61, for other cord circuits such as that containing repeater R, are placed in such condition that any one of them may be operated upon the connection of two lines by one of these other cord circuits.

The selection and connection of the networks for balancing lines L and L, has now been completed. A network (21) of the type such as networks 21, 22 and is in connection with the transformer windings 221 and 222 (at the right-hand end of repeater B, Fig. 1), because the line selection control relay of the line L to which the righthand plug of repeater R is connected has an armature connected (permanently) to a lead running to the bank of net bar magnets corresponding to the net bars to which networks of the type such as networks 21, 22 and 23 are permanently connected; and a network 24 of the type such as networks 24 and 25 is in connection with these transformer windings because the line selection control relay of the line L, has an armature connected permanently to a lead running to the bank of net bar magnets corresponding to the net bars to which networks of the type such as networks 24 and 25 are permanently connected; and a network 26 of a certain type is in connection with these transformer windings because relay 41 has an armature connected (permanently) to a lead running to the bank of net bar magnets corresponding to the net bars to which networks of that type are permanently connected. Of course, if line L were of such character that no network of the type of, say, network 24 were required to balance the line, then the armature 104 of relay 41 would be omitted (or, at least, the armature would not be connected to lead 84). Thus the lead from the middle armature of the line selection control relay for line L is disconnected from lead 102, thereby indicating that line L is of such character that it does not require a network of the type of network 24. The circuit connecting networks 21, 24 and 26 to the transformer windings 221 and 222 at the right-hand end of repeater R may be traced as follows: from winding 221 through lead 223, conducting member 224 of cord bar 1", spring contact 225, contact projection 226. conducting member 227 of net bar 2, resistance 228 of network 21, conducting member 230 of net bar 2, spring contact 231, spring contact 232, through a bridging plate to spring contact 233, spring contact 234,

through a bridging plate to spring contact 235, conducting member 236 of cord bar 1*, thence to conducting member 241 of cord bar 1 through two parallel branches, one branch extending from conducting member 236 through spring contact 237, conducting member 238 of net bar 2, network 24, conducting member 239, spring contact 240 to conducting member 241, and the other branch extending from conducting member 236 through spring contact'242, conducting member 243 of not bar 2 network 26, conducting member 244, spring contact 245, to conducting member 241, then from this juncture of the two branches at conducting member 241 through lead 247 to winding 222. A condenser forming part of the network 21 is bridged between the midpoint of resistance 228 and the midpoint of resistance 246.

The circuit connecting networks, 22, 25 and 27 to the transformer windings 248 and 249 at the left-hand end of repeater R will not be traced, since it is similar to the circuit just traced.

In order to provide for taking'care of an overflow or unusual demand for certain types of balancing networks, lamps such as 250, 251 and 252 are provided to indicate to the operator the type of network required when all of the networks of any type which are capable of selection and connection by the cross-bar switch are in use, and lamps such as 253, 254, 255 and 256 are provided to indicate to the operator the cord on which the network is required, and variable impedance cord circuits 257, 258 and 259 are provided which the operator can plug into the cord which one of the lamps such as 253 to 256 has indicated as requiring a balancing network. The operator adjusts the impedance of the circuit such as 257, 258 and 259 to form a network of the type which one of the lamps such as 250 to 252 has indicated is required.

The operation of the system as regards this feature will now be described on the supposition that all of the networks of the type such as 21, 22 and 23, except network 23, are in use when the operator inserts plugs P and P into the jacks of lines L, and L,, 4

respectively, as mentioned above. Then the cross-bar switch and its associatedcircuits will select and connect to transformer windings 221 and 222 the network 23, instead of network 21; for the circuit between lead 84 and winding of pick-up magnet will be open at armature 86 of magnet 80, and the circuit from lead 160 through armatures 161 and 163 to winding of pick-up magnet 151 will be open at armature 163, and the following circuit will be energized for operating net bar pick-up magnet 260 corresponding to network'23: from ground through battery 43, through elements 44, 46, 64, 66,67, 74 '75, 76, 81, 79, 82, 73, 83, 84, 155, a lead and an armature corresponding to lead 261 and arn'i'ature 262' (but associated with the repeater cord which is in connection with network 22), a lead corresponding to 263 (but associated with the last mentioned repeater cord), extreme left-hand conducting member of the cord bar through which not work 22 is in connection with the last mentioned repeater cord, througha spring contact on the last mentioned cord bar to the extreme upper conducting member of net bar 2*, lead 264, middle armature of pick-up magnet 151, right-hand armature of winding of pick-up magnet 260, pick-up magnet 260, left-hand armature of. magnet 260, armatures 167 and 90, leads 91, 92 -and 93, armature 94 of line selection control relay 41 to ground. I

The locking circuit'for the ick-up and locking magnets of net bar 2 wi 1 be similar to the locking circuits hereinbefore traced for the net bar magnets of. net bars 2, 2, 2, 2, 2 and 2, and maybe traced from ground through battery 43, elements 43, 44,

46, 64, 66, 67, 74, through branch-115 and branch 75, and 135 to lead 116, thence to cord bar conducting member 117, the spring contact immediately above spring contact 243, the corresponding conducting'member of netbar 2", the Winding of locking magnet and the winding of pick-upmagnet 260 of net bar 2", the extreme lefthand contact spring of magnet 260, lead 265 to ground- Net bars 2 and 2 will be operated by means of pick-up circuits through windings of magnets and 165and locking circuits through windings of magnets 95 and 123 in series, and windings of magnets and'129 in series, all just as hereinbefore described. Also in the ifashion described-above, following the operation of magnet 260 magnet 79 releases, magnet 69 operates, magnet 41 releases, magnet 49 operates,magnet 156 re leases, magnets35 and 15operate, and net bars 2" and 2 are operated by means of pick-up circuits through magnets 171 and 184, and lockingcircuits through windings of magnets 171 and 206 in series and windings of magnets 184 and212 in series.

However, magnet 150 does not release when armatures 177and 190 of pick-up magnets 171 and 184 are attracted, for mag not 1.50 remainsenergized over the following circuit 1 from ground througlixl'iattery 43, elements 44, 46, 64, 66, 67, 74, 75, 76-, 142, 144, 145, 146, 152, winding of magnet 150, elementsi153, 149, 154, 84, 155, 141, 156, 157, the extreme upper one of spring contacts 3 which cooperates with net bar 2", the extreme upper conducting member of net ban-2", lead 266, middle armature of magnet 260, lead 267 lamp- 253, armature 148 to ground.

The current through the circuit just trace-d lights lamp 253 and lamp- 256 has already beenlighted by current from ground through the battery at lamp 250,- lamp 250, left-hand armatureof magnet 260, left-hand arn'iature of magnet 151, left-hand armature of magnet 80, leads 91, 168 and 169, arm-aiure 170 of line selection control relay 35 to ground.

Lamp 256 indicates to the attendant that all of the regular networks of the type such as networks 21, 22 and 28 are in use and that an auxiliary network of such type is demanded, and lamp 253 indicates that the repeater cord on which the auxiliary network is required is the cord corresponding to cord bar magnet 15.

Therefore, the attendant adjusts the impedances of network 257 to form a network of the required type and inserts plugs 267 and 268 in jacks 269 and 270, thereby inserting network 257 inseries with the parallel circuit branches comprising networks 25 and '27, and also lighting lamp 271 over a circuit will be traced hereinafter, and also breaking at spring contact 272 the circuit of magnet 15.

The circuit connecting networks 257, 25 and 27 to the transformer windings 248, 249 may be traced as follows-: from winding 248 through lead 273, ring conductor of jack 269 and plug 267, right-hand side of network 257,'ring conductors of plug 268 and jack 270, lead 274. the plate bridging the two lower ones of spring contacts 3 opposite net bar 2, the short circuiting plate bridging the two loweronesof spring contacts 3, opposite net bar 2*, the plate bridging the two lower ones of spring contacts 3 opposite net bar 2", to cord bar cond'ucting member 27 5. thence to cord bar conducting member 276 through two par-V allel branches, one branch extendingfrom cord bar conductingmember 275 through extreme lower spring contact 3 opposite net bar 2, :(treme lower conducting member of net bar 2", network contact projection immediately below contact projection 208, spring contact 3 immediately below contact 267, to cord bar conducting member 276,. and the other branch extending from cord bar conducting member 275 through extreme lower spring coiitac't 3 opposite net bar 2, extreme lower conducting member of net bar 2, network contact pro jection immediately below contact projection. 214, spring contact immediately below spring contact 213, to cord bar conducting member 276, then from this junction of the two branches at member 276 through the plate bridging the middle pair of spring contacts 3' opposite net bar 2 the plate bridging the middle pair of spring contacts 3 opposite the net bar 2', the plate bridgthe middle pair of spring contacts 3 opposite the net bar 2, lead 277, the tip conductor or jack 27.0 and; plug 268, the lefthand side of network 257, the tip conductors of plug 267 and jack 269, lead 278 to transformer winding 24-9.

The circuit over which lamp 271 is lighted, as mentioned above, may be traced as follows: from ground, through battery 13, elements ll, 16, 64. 65, 67, 7a, 75, 76, 1- 12. 1%, through resistance 218 in parallel with the armature of magnet 150, thence through lead 200, the sleeve conductors of jack 270 and plug 271, and lamp 271 to ground. Lamp 271 remains lighted as long as the network 257 is required by the re peater cord corresponding to plug P, but when the connection through repeater R is taken down, the lamp 271 is extinguished so that the attendant will be advised that plugs 267 and 268 may be removed from jacks 269 and 270.

When the circuit of cord bar magnet 15 is broken at ack contact 272, as mentioned above, that magnet releases, breaking the circuit traced above including armatures 148 and 149. winding of magnet 150 and lamp 253. Therefore lamp 258 becomes 1';- tinguished. Also, magnet 150 releases, connecting-magnet 139 in parallel with resistance 218. hlagnet 139 then operates, causing magnet 35 to open and extinguish lamp 250 and also causing magnet 56 to operate.

The operation of armature 145 of magnet 56 opens a gap in the circuit traced above for cord bar magnet 15, but that circuit has already been broken at ack contact 272 as described above. The operation of armature 220 of magnet- 56 breaks the circuit of magnet 42 at contact 55, thus causing the breaking at 64 of the connection traced above from battery 43, to lead 67. How ever, before this break at 64t occurs, armature 220 by engaging spring contact 55 connects battery 136 to lead 67, this connection being traceable from battery 136 through elements 137, 48, 50, 51, 52, 53, 54;, 55, armature 220 to lead 67. Thus magnets 69 and 49, the pick-up and locking magnets of net bars 2*, 2 and 2, magnets 139 and 56, and the pick-up and locking magnets of net bars 2 and 2 are maintained energized from battery 136 until the circuit traced above from lead 136 to lead 67 is broken at armature 51 or 53 by the deenergization of magnet 36 or 30, due to the removal of plug P or P.

The breaking of the circuit of magnet 42. as mentioned above, and the consequent release of its armatures 64: and 65 also conditions the magnets such as 45 and 61 for operation upon the connection of two lines by a repeater cord other than that of the repeater R.

Of course, it it had been required that an auxiliary net work of the type such as networks 21, 22 and 23 be connected to transformer windings 221 and 222 instead of to transformer windings 248 and 2 19, then the attendant would have plugged the network 257, or some other network of the same type into jacks 279 and 280 instead of into jacks 269 and 270.

Network 257 is of the same general type as networks 21, 22 and 23; but it it were required that an auxiliary networkot the same generaltype as networks 2 1, 25, 26 and 27 be connected to the transformer windings 24:8 and 2-19, the attendant could adjust the impedance of either of the networks 258 or 259, (or of any one of any provided number of such networks) to form the proper network and plug it into either of the jacks 281 or 282, or into any one of any number of such jacks which might be provided. Or the attendant could adjust the impedance of the condenser and the lower half of the re sistances of network 257 to form a network of the required impedance and insert plug 268 into either of the jacks 281 or 282, leaving plug 267 disengaged from all jacks.

Any desired number of cord bars and repeater cord circuits, and any desired number of net bars with networks of any desired impedances permanently connected thereto, and any desired number of auxiliary networks of any desired impedance may be used, the number and character of such elements desired being dependent upon the number and character of the lines to be interconnected by repeater cords and the volume of traflic over each line.

that is claimed is:

1. A cross-bar switch comprising a bar carrying contact means and bridging means carried by said bar for electrically connecting certain of said contact means together in one position of said contact means and breaking said connections in another position of said contact means.

2. A cross-bar switch comprising a bar carrying yielding contact members, brie ging members carried by said bar for electrically connecting certain of said contact members together, and a bar carrying contacts for engaging with said yielding contact members and disengaging said yielding contact members from said bridging members 3. A cross-bar switch comprising two movable switching bars intersecting each other, carrying cont-acts adapted to be engaged when said bars are operated, and electrical contact means adapted to conneetively engage the contacts of one of said bars when said bars and their contacts are in their normal or unoperated position.

4:. A cross-bar switch comprising two bars intersecting each other, contact means on one of said bars, contact means on said other bar adapted to engage said first contact means upon operation of said bars, and contact means engaging said first contact means, said last-mentioned contact means being dis engaged from said first contact means upon operation of said bars to engage said first and second contact means.

A selective switch comprising coordinately arranged sets of back, front, and active contacts and means to separately operate said sets of contacts.

6. A selective switch comprising coordinately arranged sets of back, front, and active contacts and electromagnetic means to separately operate said sets of contacts.

7. A selective switch having active contacts, back contacts for establishing connec- In witness whereof I hereunto subscribe 20 my name this 11th day of October, A. D., 1923.

ROY D. CONWAY.

Images