US1296680A - Telephone-exchange. - Google Patents

Description

Patented Mar. 11,1919.

2 SHEETS-SHEE1'1.

In v e n for James L. M 0a arr/e.

' J. L. McQUAR RiE.

TELEPHONE EXCHANGE.

APPLICATION FILED NOV. 26, 1912.

J. L. McQUARRIE.

TELEPHONE EXCHANGE.

APPLICATION F ILED .NOV. 26, 1911.

, 1,296,'680.- Patnted Mar. 11,1919.

2 SHEETS-SHEET 2.

//7 van for James L MOuarr/e.

UNITED STATES PATENT OFFICE.

J'AMES L. MGQUARRIE, OF MONTCLAIR, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, NEW YORK, N. -Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE.

Specification of Letters Patent.

Patented Mar. 11, 1919.

npplicationnlegl November 26, 1917. Serial No. 203,971.

To all whom ,it may concern:

Be it known that I, J Arms MCQUABRIE, a citizen of the United States, residing at Montclair, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone-Exchanges, of which the following is a full, clear, concise, and exact description.

This invention relates ,to telephone exchanges wherein the interconnection of subscribers lines is effected by automatic switching apparatus.

More particularly it relates to the construction and operation ,of selectively operated switches employed in exchanges of the above character.

Heretofore it has been the practice to provide for ,each switch an individual operating mechanism comprising primary and secondary stepping magnets, together w th other elements necessary to control the operative functions of the switch. In accordance with such an arrangement each switch of the exchange has allotted thereto its own individual actuating mechanism, which is brought into service only at such times as the particular switch is appropriated for use in the extension of a connection. The actual time during which a switch operating mechanism is engaged in actuating its individual switch shaft'is of course of comparatively short duration. After having so performed the function of setting its switch shaft, the operating mechanism remains inactive until such switch is again chosen to extend or complete another connection.

The main feature of the invention is to obviate the necessity of an individual ope-rating apparatus for each switch by a switch construction in which a group of step-bystep switches, as for example,'ten selectors, is provided with a plurality of stepping devices, any one of said devices being operable to engage and actuate any one 5 of the switches of the group.

Anotlihr feature is that each of these common orinaster stepping devices, after having completed its operation of stepping a switch into connection with a desired set of terminals, .does not remain inactive, but immediately proceeds to move into operative relation to the next switch in the group which it finds in proper condition to be appropriated for use in extending another connection. Due to this arrangement, the total number of switch operating mechanisms for the exchange may be reduced, and the number of such mechanisms serving a group of switches may be materially less than the number of switches comprising the group, without reducing the percentage of available switches.

Still another feature is the provision of a releasing device common to the switches of a group, and means for moving the same into position to restore any one of the switches which is in proper condition to be returned to normal.

These and other features will become more apparent from a consideration of the following description and the appended claims.

In the drawings, Figure 1 is a perspective view showing a switch structure arranged in accordance with one embodiment of my invention. This showing illustrates a portion of a group of selective switches, and also the manner in which the common actu ating devices are arranged to cooperate with the switch shafts. For the sake of clearness, various parts are shown diagrammatiand others are omitted entirely. While provision is made for only two master devices it will of course be understood that the number of such devices depends largely upon the size of the group they serve and also the percentage of available switches necessary to afford the desired service to the particular exchange involved.

Fig. 2 shows a subscribers telephone substation together with a portion of the cir cuit arrangement for controlling the operation of the switches illustrated in the cm bodiment of Fig. .1.

Referring tofthe drawings, a plurality of step-by-step actuated switch shafts 1 arranged in a row comprise a group of switches under the control of common actuating devices, Mounted on the upper end of shaft 1 is a set of brushes 2, 94 and 95 adapted to be positioned in operative relation to any desired level of terminals 3 in the vertical movement of the shaft, and subsequently rotated into contact with a particular set of terminals in such level. Each shaft is provided with a plurality of vertical ratchets 4 and rotary ratchets 5 to be engaged by stepping pawls for moving the switch into its various operative positions. Each shaft 1 also has a vertical holding ratchet 6 and a rotary holding ratchet 7.

Parallelly disposed with respect to each other and arranged adjacent to theswitch shaft 1 are a plurality of helically threaded members or endless worms 8. These worms are journaled for rotation in suitablebearings (not shown) and have secured upon their ends ratchet wheels 9. A stepping pawl 10 pivoted to the armature 11 cooperates with ratchet 9 to rotate the worm a distance corresponding to one tooth for each energization of the drive magnet 12. A supporting structure 13 is loosely mounted upon the worm 8 and is provided with any suitable means for engaging the endless slot diagrammatically shown at 14, whereby said structure and its associated elements are carried by rotation of the worm 8 back and forth before the switches of the group. A pair of fixed rods 15, upon which the structure 13 is also slidably mounted, serve as a guide and support to insure accurate movement and positioning of the stepping device. Riveted to the supporting frame 13 is a bracket 16, upon which is mounted the primary or vertical stepping magnet 17. The upper end of support 13 is overturned and slotted to receive the armature '18, which is pivotally attached theretofand has one end extending into position to be attracted by magnet 17. The other end of said armature carries a steppingpawl 19' arranged to engage ratchet 14 upon the energization of the stepping magnet when the master device is operatively positioned before a switch shaft. The support 13 also has an inwardly extending bracket 20 to which is secured the secondary or rotary stepping magnet 21. Said rotary magnet has an armature 22, one end of which is pivotally attached to the frame 13, and the other end provided with a stepping pawl for engaging the ratchet 5 upon energization of magnet 21. The

lower end of frame 13 is bent over to fornr a supporting table 23, upon which'is mounted a magnet 24. This magnet has an armature 25 also pivoted to frame 13. Armature 25 has its free end projecting into such position that upon the energization of magnet 24, when the master device is positioned before a switch shaft 1, said armature engages a pin 26 upon a rod 27 for the purpose ,of urging such rod in a downward direction. The function of this rod will hereinafter be more fu ly considered. It will also later appear t at magnet 24 serves to reset certain auxiliary switches associated with the operating circuits of the selective switch.

Positioned before and individual to each switch shaft l is a set of contact springs 28. This set comprises seven pairs of contacts, the upper six of which are-open and the lower one closed while there is no tension exerted upon the spring members. When,

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however, a master mechanism positions itself before the switch, a pin 29 presses against the under side of the block 30 to close the first mentioned group of contacts and to open the lower set. At the same time a pin 31 of insulating material, carried on the underside of the table 23, bears on the contact spring 79 and forces it to close on its cooperating spring. A strip 34 having an integral contact member 35 is so arranged between switch positions as to normally remain in open relation to a cooperating contact spring 36. But when a master device, under the influence of the driving worm 8, leaves its position of operation before one switch, the pin 31 presses strip 34 downward and retains the same in closed contact with spring 36 until said device has completed its travel to its operative position before the next switch shaft 1, at which time the strip 34 is released and the contacts 35, 36 are again opened.

Each stepping mechanism has a set of contact strips generally designated at 37, arranged parallel to the path of movement of said mechanism, and extending before all the switches of the group. Said set comprises nine separate contact strips, which, as shown in Fig. 1, are insulated from each other by the interposition of insulating material, and may be securely held in proper position by any convenient means. Securely mounted upon the supporting table 23 of-the frame 13 is a set of brushes 38, one for each of the strips of the set 37,

coiiperatingwith said strips in such manner as to maintain a sliding resilient contact therewith throughout the complete travel of the master device. The brushes of the set 38 are insulated from each other, and, as will more clearly appear hereinafter, serve to convey current to and from the operating magnets carried by the movable structure.

Mounted upon a pivot 39 are the vertical and rotary holding dogs 40 and 41 respectively, which coact with the holding ratchets 6 and 7 to retain the shaft 1 in its actuated position. An endless worm 42, similar to worm 8, is arranged adjacent the switch shaft 1, a'nd'has mounted thereupon the release magnet supporting frame 43. Said frame engages the endless spiral slot 44 so as to be driven axially along the worm 42 when the same is rotated. The ratchet 45, actuated by armature 46 of the stepping magnet 47, serves as a driving means for the worm. A rod 48, upon which the frame is also slidably mounted, serves to guide the same in its movement before the switch shafts. The release magnet 49, which issecured to themovable frame 43, is arranged'so that when positioned before a switch shaft and energized it will attract the flanged portion 50 of dog 41 to withdraw both holding dogs from their engagement with ratchets 6 and 7, thereby permitting the shaft 1 torestore. Current is conveyed to magnet 49 by way of the feed strips 51, 52 and brushes 53, 54. An insulating finger 55, carried on the arm 56 of the frame 43, cooperates with the contact members 57 and 58 in a manner similar to that described in connection with the master operating mechanisms. v

Having described in detail one embodiment of a switch structure in which my present invention resides, I will now explain the manner in which it is calculated to operate by describing the circuits designed to perform the various functions involved in the extension of a telephone connection. For the purpose of explanation it will be assumed that the telephone system in which the present invention is used, employs finder or other preliminary switches, first selectors, second selectors, and connectors. The switches shown and described in the drawings will be considered as used in the capacity of second selectors. According to the well known practice of trunking, each level of trunks in a first selector leads to a group of, say, then second selectors, all of which have access through the succeeding connectors to any line in a given one thousand lines. Therefore, since the second selector switches may be considered as divided into groups according to the numerical grouping of subscribers lines, a convenient adaptation of the present invention is to provide each such group of second selectors, as shown in the drawings, with a plurality of common stepping devices. A first selector, in testing any particular level of its trunks, may then obtain any second selector of a group that is served by a number of common actuating devices.

Assume that the subscriber at substation 59, Fig. 2, desiring to converse with some other subscriber, removes his receiver from the hook to start the operation of a finder or line switch. Such switch, which is diagrammatically illustrated by the broken lines in the figure, operates in the well known manner to connect the line conductors 60 and 61 to the trunk conductors 62 and 63, terminating in brushes 64 and 65 of a first selector switch. The subscriber now operates his sender to transmit a given number of impulses to the operating mechanism of the first selector, whereby the brushes 64, 65, 66 are moved into operative relation to the desired level of trunk terminals. Terminals 67, 68, 69 represent the first set of terminals in such level and are associated by means of trunk conductors 70, 71, 72 with brushes 94, 95, and 2 of a second selector switch, as those shown in Fig. 1. Assume now that the switch shaft 1 associated with the trunk 7 0, 71, 72 is in its normal restored position, and that a master stepping mechanism, such as the one shown in Fig. 2, has previously been positioned before such switch in readiness to operate the same as soon as taken for use This being the case, the pins 29 and 31 on the supporting frame 13 are holding the con tacts of the set 28 and contact 32 respectively in their alternate positions, whereby contacts 7 3 to 79 inclusive, Fig. 2, are closed, while contact 80 is open. The contact 80 by being open places a break point in the following circuit from the test contact 81" to ground: test contact 81, conductor 82, contact 80, conductor 88, contact 80, conductor 84, to ground at the off-normal contact 85.

Therefore, when the first selector switch begins its secondary or hunting movement and takes its first step onto the trunk terminals 67, 68, 69, no guarding ground potential willbe found by test brush 66 upon test terminal 69, thereby indicating that the switch associated with the trunk 70, 71,72 1s in proper condition to be selected. Thereupon the first selector comes to rest and-extends'the connection by way oftrunk conductors 7 0 and 71 to the switch shown in th drawing. A circuit is now closed for the line relay 86 from free pole of battery, upper wlnding of such relay, upper armature and contact of cut-off relay 87, conductor 88, closed contact 78, conductors 89 and 7 0, terminal 67, brush 64, conductors 62 and 60, over the loop of substation 59, c0nduct0rs'61 and 63, brush 65, terminal 68, conductors 71 and 9(), closed contact 74, conductor 91, inner lower armature of cut-ofi relay 87 lower winding of relay 86, to ground. Relay 86 on attracting its armaturecloses a circuit for the slow relay 92, traceable from ground, armature and front contact of relay 86, relay 92, to the free pole of battery. The relay 92 energizes and at its right-hand armature places a ground, by way of the following circuit, upon all multiples of the test conductor 72 at the first selector switches, so

that any other switch testing such multiples will find the same guarded so long as relay 92 remains energized: ground, right-hand armature and contact of relay 92, conductor 93, closed contact 77, conductors 82 and 72, to test contact 69 and other multiples thereof.

The calling subscriber, proceeding to manipulate his sender in accordance with the second digit of the called number, interrupts the above traced circuit of line relay 86, thereby causing the same to vibrate its ar mature a corresponding number of times. Upon the first retraction of said armature the following circuit is closed for the slow relay 96: ground, armature and back contact of relay 86, inner left-hand armature and front contact of relay 92, winding of relay 96, to battery and ground. Relay 96 by energizing establishes acircuit for escape magnet 97 from ground, armature and contact of relay 96, side-switch arm 98-and its first position contact, winding of magnet 97, to battery and ground. The following circuit is also closed at the same time for the primary stepping magnet 17 of the master mechanism: ground, armature and back contact of relay 86, inner left-hand armature and front contact of relay 92, side-switch arm 99 and its first position contact, contact strip 100, brush 101, winding of stepping magnet 17, brush 102, contact strip 103, to battery and ground. Said magnet 17 thereupon attracts its armature 18 and through the agency of pawl 19 and the vertical ratchet 4 steps the shaft 1 up one step. Likewise, for each succeeding retraction of the line relay 86, an impulse is sent to magnet 17 and the shaft 1 is elevated to position its brushes 94, 95 and 2 in operative relation to the desired level of contacts in the bank 3.

At the termination of the second series of impulses the line relay 86 holds its armature attracted, and after a sufficient period has elapsed relay 96 denergizes, thereby opening the circuit of the escape magnet 97. Magnet 97 by deenergizing allows the side switch to escape into second position. In such position magnet 97 is immediately energized over the following circuit: free pole of battery, winding of magnet 97, sideswitch arm 98 and its second position con tact, conductors 104 and 105, closed contact 78, conductor 106, secondary off-normal contact 107, to ground. lVith the side switch in second position a circuit is also completed as follows for the secondary magnet 21 of the master mechanism: ground, side-switch arm 108, contact strip 109, brush 110, contact and armature of magnet 21, brush 111, contact strip 112, to battery and ground. Upon energizing, the stepping magnet 21 attracts its armature 22 to automatically rotate the shaft 1, carrying the brushes 94, 95 and 2 step by step, over the trunk terminals of the selected level. Busy trunks are identified by the presence of a ground upon their test terminals. At the first rotary step of the shaft 1 the secondary off-normal contact 107 is opened, thereby opening the energizing circuit previously traced for the escape magnet 97. If, however, the first trunk in the level upon which the brushes 94, 95 and 2 are momentarily resting, is busy, a holding circuit is established for escape magnet 97 as follows: battery, winding of magnet 97, side-switch arm 98 and its second posi tion contact, conductor 104, closed contact 75, conductor 113, test brush 2, to the grounded test terminal 114. The side switch thus remains in position 2 and the magnet 21, interrupting its own circuit, continues to rotate the switch until its brushes encounter an idle trunk. When this occurs the escape magnet becoming deenergized steps the side switch into position 3, thereby bringing the selector switch to rest.

As the side switch arrives in third position a circuit is completed from ground, side-switch arm 108, contact strip 115, brush 116, winding of magnet 24, brush 117, contact strip 118, to battery. Magnet 24, upon attracting its armature 25, Fig. 1, causes the same to engage the pin 26 on vertical rod 27 to move said rod downwardly against the end of lever 119. Lever 119 being tilted about its pivot 120 presses against the pin 121 to engage the springs 81, 122 and 123 with their respective contacts. As seen in Fig. 2, this results in extending the trunk 70, 71, 72 through to brushes 94, 95 and 2 of the selector, as soon as said selector has completed its secondary movement. The shouldered end of lever 119, against which the upper end of the intermediate lever 124 normally rests, as shown in the figure, being tilted upwardly by the action of rod 27, permits lever 124 to escape its engagement with the shouldered end of lever 119 and to rotate, by the tension of spring 125, so that its upper end now bears against the under straight surface of said. lever 119. This new position of lever 124 locks lever 119 in the position to which it was actuated by magnet 24 to hold contacts 122, 123, 81 closed during the engaged period of the switch, since, as will presently appear, the magnet 24 soon becomes inactive after having actuated the rod27. The above described rotation of intermediate lever 124 is made possible at this time due to the fact that the ratchet 7 having moved up out of contact with lever 126, the retractile spring 127 withdraws lever 126 out of the path of said lever 124. The magnet 24 also acts upon its energization to reset the side switch to its normal position. l/Vhile the side switch is momentarily standing in position 3 before being reset by magnet 24, the following circuit is established: ground, sideswitch arm 108, contact strip 115, brush 116, left-hand armature and contact of relay 24, brush 128, contact strip 129, conductor 130, thence by one path to the contact and armature of the master drive magnet 12, winding of said magnet to battery; and by another path to the winding of cut-off relay 87, to battery. Relay 87 and magnet 12 energize in the circuit traced. Reset magnet 24, which was momentarily energized while the side switch stood in position 3, does not, however, immediately deenergize when said switch restores, but looks up as long as slow relay 92 retains its armatures attracted over the following circuit: battery, contact strip 118, brush 117, winding of magnet 24, righthand armature and contact of said magnet, brush 131, contact strip 132, conductor 133, outer left-hand armature and front contact of relay 92 to ground. Magnet 24 by holding its armatures attracted affords a new energizing circuit for relay 87 and magnet 12* during the time that slow relay 92 is holding its armaturesin their attracted position'.v This circuit is traceable from ground, outer leftdiand armature and front contact of relay 92, conductor 133, contact strip 132, brush 131, contact and right-hand armature of magnet 24,- left-hand armature and contact of said magnet, brush 128, contact strip 129, conductor 130, to magnet 12 and relay 87 as above tracedn Relay 87 by -energizing cuts off the line relay 86, and-the master'drive magnet 12 byv energizing in the above traced circuit vibrates its armature 11 to engage ratchet 9, and thereby rotate the endless worm 8. Rotation ofsaid wormcauses the supporting frame '13 with the master stepping magnet to move away from its operative position before the switch just actuated and to advance toward the next switch in the group. At the first movement of said master device, the pins 29 and 31 permit the contacts 73 to SO-inclusive to assume their normal positions as shown in Fig. 2. Furthermore, the pin-31, having moved onto the strip 34, presses the same into contact with spring 36. This results in the closure of the following circuit which takes the place of the circuit previously traced from the magnet 12 and relay 87 in parallel therewith to ground atslow relay 92: ground, contact strip 34, contact 36, conductor 134i, outer left hand armature and back contact of relay 92, conductor 130, to magnet 12 and also relay 87. Thiscircui-t keeps the magnet 1-2-actuating and insures a complete movement of the master device-to its operative position before the next switch. If, upon the master device reaching its position before the next switch, such as the switch represented generally by the contact group 28 in Fig. 2, andthis switch is already actuated, the following circuit is established: from magnet 12 and relay 87 in parallel, conductor 130, outer left-hand armature and back contact of relay 92, conductor 134C, to a'closed contact corresponding to 79 of the set 28", a conductor similar to 135, to ground at anofi' normal contact 85 of the busy switch. Therefore the drive magnet 12 con-- tinues to move the master device past the actuated switch and on to the next one in order; 4

' Assume-now that this nextswitch is in its normal position and has a master mechanism standing before it, similar to the one illustrated'in detail in Fig. 2, andwhich in its travel before the switches cooperates with the lower sets of contacts in the figure, such as the set-73" to 80' inclusive. In such event the master'device under discussion upon arriving before such switch completes the following circuit for its relay 87 and drive magnet-12: relay 87 and magnet 12 in parallel, front contact and lower armature of relay 87, conductor 136, a closed contact similar to76 of the set before the assumed switch, a conductor similar to 137, a closed contact similar to 7 6 before which there is already a master device resting, over the conduct-or 136, to ground at the lower armature and back contact of the cut-off relay similar to 87 of such master device. Hence the magnet continues to energize and the master device passes by said switch, which already has a master device resting before it, and in the manner already described goes on to the next selector switch.

If the next switch encountered is in nor mal position and has no master device already before it, then when the seeking master device assumes its position before such switch, the operating circuits above described for the drive magnet 12 and relay 87 are opened, and said device comes to rest, ready to operate said switch when taken for use.

Returning to the point where the first selector had positioned its brushes 64:, 65 and 66 upon the terminals of trunk 70, 71, 72, it will be remembered the assumption was that the second selector switch associated with said trunk was idle and had a master device positioned before it. If, however, the switch is idle but has no master device associated therewith, it is obvious that said switch is not in proper condition to be selected and should therefore test busy to the preceding switch. This condition is obtained as follows: Since there is no master device before the switch, all of the contacts 80,80, etc, are closed so that when brush 66 makes its test of trunk 72 a ground is found thereon. The circuit affording this ground is traceable from test trunk 7 2, conductor 32, through the closed contacts 80, 80, etc, in series, to ground at the off-normal contact 85.

If the switch hadbeen previously actuated and was busy extending a call when the above mentioned test was made, a ground would have been present on test conductor 72 by way of test terminal 114, brush 2, and contact 81. From the foregoing it is apparent that a switch, in order to be selectable to a preceding switch, must not only be idle and restored but must also have amaster stepping mechanism associated therewith. It is also obvious that a master device having per formed its function on one switch, immedi ately starts out in search of the next switch in order that is incondition to have a master device associated therewith.

Should, for any reason, the subscriber abandon his call while the side switch is in second position, the following circuit is closed for the reset magnet 24 to restore the side switch to normal: ground, armature and back contact of relay 86, inner left-hand armature and back contact of relay 92, conductor. 138, side-switch arm 139 and its sec- 0nd position contact, contact strip 140, brush 141, winding of magnet 24, brush 117, contact strip 118, to battery and ground. At the same time the following circuit is established for the drive magnet 12 to move the master device away from the selector switch: ground at the armature of relay 86, orer the circuit just traced to the brush 141, thence by way of the left-hand armature and contact of magnet 24, brush 128, strip 129, con ductor 130, magnet 12 to battery.

Considering now the release mechanism it will be described how the magnet 49 which is common to all switches of a group is capable of locating such switches as are in proper condition to be returned to their normal position. The magnet 47 which drives the worm 42, receives its energization over the following circuit: free pole of battery, wind ing of magnet 47, armature and contact of said magnet, contact and armature of relay 142, to ground. So long as relay 142 remains inert, the magnet 47 interrupting its own circuit will drive the release magnet 49 back and forth before the switch shafts 1. Relay 142 is arranged to receive sufiicient current through resistance 143 only when conductor 144 is free from ground connections. If magnet 49 passes before a switch that is idle the pin 55 on arm 56 by closing contact 58 places a ground on conductor 144 as follows: ground, off-normal contact 85, conductors 84 and 113, closed contact 58 to conductor 144. The relay 142 remains deenergized and magnet 49 continues its movement, due to a ground on conductor 144 by reason of the closed contact 57, to the next switch position. If the next switch is being actuated a ground is extended to conductor 144 from a secondary off-normal contact 107, a conductor similar to 106, a closed contact similar to 78, a conductor as 104, a closed contact similar to 75, a conductor similar to 113, aclosed contact 58, to conductor 144, while said switch is in its primary movement. But if the switch is in its secondary movement, contact 107 is open, and the ground is now afforded from busy test terminals 114, by way of a conductor similar to 113 to conductor 144.

VVhe-n, however, the release magnet 49 positions itself before a switch which is idle and in condition to be restored, no short-circuiting ground is present on conductor 144, and consequently relay 142 attracts its armatures. This opens the circuit of magnet 47 thus stopping magnet 49 in operative relation to the flange 50. A circuit is also closed for magnet 49 from ground, armature and contact of relay 142, strip 51, brush 53, winding of magnet 49, brush 54, strip 52 to battery. Magnet 49, thereupon attracts the flange 50 to rotate the holding dogs 40 and 41 out of engagement with the holding ratchets 6 and 7.. This movement of flange 50' carries the trigger 145 behind the catch 146 of lever 124, thereby locking the holding dogs 40 and 41 away from their ratchets to insure a complete restoration of the shaft 1. At the same time finger 147 closes contact 148, whereupon a ground is again placed on conductor 144, which in turn deenergizes relay 142, and the drive magnet operates to drive the release mechanism to the next switch. When shaft 1 reaches normal, the ratchet 7, through the agency of lever 126, restores levers 124 and 119 to their normal positions as shown in Fig. 1, thereby opening contacts 122, 123, 81. and 148, and also unlocking holding pawls 40 and 41.

In detailing the successive steps and op erations, and accounting for the various conditions to be met with in building up a connection in a telephone system embodying my present invention, I have described my improved switches as serving in the capacity of second selectors. However, it will be clearly understood that the above description does not limit the scope of the invention, but is merely exemplary of the numerous adaptations contemplated thereby. It is obvious that the switches shown and described herein may be used as any one of the particular classes of switches employed in extending a telephone or other connection between two points.

No claim is made herein to the features of the circuit arrangement disclosed, the same being described merely for the purpose of enabling a more thorough understanding of the manner in which the switches operate.

What is claimed is:

1. In a telephone exchange, a group of switches, a stepping device common to said switches, means for moving said device into position to engage and operate one of said switches, and a release device common to said switches for restoring the same to their normal positions.

2. In a telephone exchange, a group of switches, a common stepping device movable in a path forth and back before the switches of said group, and means for driving said device into position to engage and actuate any one of said switches.

3. In a telephone exchange, a group of switches, a stepping magnet common to said switches and arranged to actuate any one thereof, and means for moving said magnet into operative relation to one of said switches.

4. In a telephone exchange, a group of switches, a stepping magnet common to said switches and arranged to actuate any one thereof, and a second stepping magnet for moving said first magnet into operative relation to each of said switches.

5. In a telephone exchange, a group of switches, a plurality of stepping magnets common to said switches and arranged to actuate any one thereof in a plurality of directions, and means for moving said magnets into operative relation to each of said switches.

6. In a telephone exchange, a group of switch shafts, a worm adjacent to said shafts, a common stepping mechanism for actuating said switch shafts, said mechanism being mounted upon said worm and having an operative position thereon for each switch shaft, and means for driving said worm to move said mechanism from one position to another.

7. In a telephone exchange, a group of switches, a commonl operating device movable in a path forth and back before the switches of said group, and means for driving said device to move the same into position to engage and operate any one of said switches in a plurality of directions.

8. In a telephone exchange, a group of step-by-step switch shafts, an electromagnetically operated stepping pawl arranged to engage and actuate any one thereof, and means for moving said pawl into operative relation to any one of said shafts.

9. In a telephone exchange, a group of switches, a unitary structure movable in a path before the switches of said group, said structure including primary and secondary stepping magnets common to and adapted to actuate any one of said switches, and means for moving said structure to position the same in operative association to one of said switches.

10. In a telephone exchange, a group of switches, a plurality of devices, each arranged to engage and movesaid switches in a plurality of directions, and means for op eratively associating any one of said devices with any one of said switches.

11. In a telephone exchange, a switch shaft, a plurality of stepping devices, each arranged to engage and actuate said shaft in a plurality of directions, and means for operatively associating any one of said devices with said shaft.

12. In a telephone exchange, a group of switches, a plurality of common devices arranged to engage and operate said switches,

a-screw shaft individual to each device for moving the same into operative association with any one of said switches, and means for driving said shaft.

13. In a telephone exchange, a group of switches, a plurality of unitary structures common to said switches, each including pri. mary and secondary operating magnets, and means for moving any one of said structures into position to operate any one of said switches.

14. In a telephone exchange, a group of stepby-ste switches, a plurality of stepping magnets common to said switches, and stepping means for placing any one of said magnets in position to move any one of said switches.

15. In a telephone exchange, a group of switches, means for actuating said switches, a releasing mechanism common to said switches, and step-bystep means for moving said mechanism into position to restore any one of said switches to its normal position.

16. In a telephone exchange, a group of switch shafts, means for moving said shafts to their operative positions, a worm arranged adjacent said shafts, a release magnet common to said shafts mounted on said worm and having positions thereon for releasing each of said shafts, and a stepping magnet for driving said worm to move said release magnet to any of such positions.

17 In a telephone exchange, a row of vertical switch shafts, a plurality of rotatable screw shafts arranged adjacent to and ex tending before all the switches in said row, a supporting structure mounted upon each screw shaft and arranged to be moved longitudinally by rotation of said screw shaft, a pair of stepping magnets mounted upon each structure for actuatin said switch. shafts in two directions, each pair of magnets having an operative position before each switch in said row, and stepping means for rotating each of said screw shafts.

In witness whereof, I hereunto subscribe my name this 22nd day of November A. D., 1917.

JAMES L. MCQUARRIE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). G.

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