US2337941A - Switching mechanism - Google Patents

Description

Dec. 28, 1943. J. OD SHEPHERD SWITCHING MECHANISM 3 Sheets-Sheet 1 Filed July 19, 1941 INVENTOQ gUDSO/V 0'0. SHEPHERD ATTORNEY 3 Sheets-Sheet 2 J. O D SHEPHERD SWITCHING MECHANISM Filed July 19, 1941 5 fin; JSUM m m 23 W; 1%. a O T L w .0 My w w W A mu 0 4 uu\ .m 4 M B 2 JWU 2 W \M I \u h Dec. 28, 1943.

Dec. 28, 1943. I J QD SHEPHERD 2,337,941

SWITGHI N G MECHANISM Filed July 19, 1941 3 Sheets-Sheet 3 lbso/af/ax; 65

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N [/5 N TOR 0N 0'0. SHEPHERD Patented Dec. 28, 1943 UNi'lED STATS PATN'E' OFFICE SWliiiGillNG MECHANISM Judson UD Shepherd, Atlanta, Application July 19, 1941, Serial No. lliallilll 38 Claims.

This invention relates to switching mechanisms and particularly to improvements in switching mechanisms used in automatic telephone systems.

An object is to simplify automatic switching mechanisms for use in the establishing of telephone connections, to reduce the cost of such mechanisms and to improve the operation characteristics thereof.

Heretofore automatic switches have been provided with certain mechanism momentarily employed for the manipulation of any one of a plurality of such switches and then reverted or restored for common use.

The present invention relates in general to such common operating mechanism and arrangements in which a plurality of switching devices of the cross-bar switch type are associated with common mechanisms which may be used momentarily for controlling the selective operations of such switching devices.

A feature thereof is a structure comprising a plurality of switching devices of the cross-bar type in which a plurality of vertical select bars may be arranged in horizontal rows and a plurality of horizontal holding bars are provided for each row of vertical select bars with contacts at each intersecting point of a vertical bar with a horizontal bar for the establishing of a connection between contacts of any intersecting point. The connection is effected by the operation of a corresponding vertical select bar and a horizontal holding bar. A common mechanism cooperates with said switching devices, whereby any one of said vertical select bars may be selected and operated for the establishing of connections between the contacts at the cross-point of said operated select bar and any one of the holding bars associated with the horizontal row of select bars in which the operated select bar is located when said holding bar is actuated.

Another feature is an ngernent in a structure of this kind in which each horizontal row of vertical select bars is divided in a plurality of individual groups of select bars, while a plurality of horizontal holding bars remains common to each horizonta row of such groups of vertical select bars and in which the common mechanism cooperates with these groups of vertical select bars whereby any one of the vertical bars in any group may be select d and operated for the establishing of a con tion between contacts at the cross-point of said operated select bar and any one of the holding .bars associated with the particular horizontal row of said groups which the selected vertical select bar is located, when said holding bar is actuated.

Still another feature is means to extend connections between a large number of lines, say 700, and trunks, say 100, or conversely, by means of a comparatively few operating magnets which may be 127 or even less, in comparison with 1100 required in current practice. With switching arrangements of this general type it is desirable to have off-normal contacts associated with each line which are maintained operated whenever a connection is extended to or from it. This invention provides such off-normal contacts for each line to be maintained so operated notwithstanding that there is no magnet individual to the line as is required with usual arrangements.

The invention has been illustrated in the accompanying drawings, in which:

Figure 1 shows in general the construction details of a switching device in accordance with the 'applicants invention; while Fig. 2 shows in a more diagrammatic form the arrangement of the switching device in accordance with the applicants invention; and

Fig. 3 shows details of the selecting and operating arrangements for the crosspoints and the off-normal contacts individual to each vertical row of orosspoints.

For the sake of clearness in describing the applicants invention, the above-mentioned individual groups of vertical select bars arranged in horizontal rows and associated sets of contacts may be referred to hereinafter by the general term switching unit and the remainder of the mechanism may be referred to in general as he common mechanism. It should, however, be observed that the individual switching units comprising a horizontal row of vertical select bars and associated contact sets are associated with an individual group of holding bars cooperating with these units. Considered in this light, each switching unit and a part of the associated holding bars may take the approximate form, as far as the general operation and construction are concorned, of a cross-bar switch structure of the type as disclosed in the patent to J. N, Reynolds 2,021,329, issued November 29, 1935. It should, however, be observed that the cross-bar switch structure of this patent refers to the select bars as horizontal bars and the holding bars as vertical bars, while in the applicants switching units the vertical bars are the select bars and the horizontal bars are the holding bars. In the primary embodiment, consideration of the Reynolds switch, therefore, should be on the basis of it being rotated 90 degrees and suitably modified as will be understood from what follows.

If reference is now made to Fig. l of the drawings one of these types of switching units is illustrated in more or less diagrammatic form in this figure at It showing one of a plurality of vertical select bars i| having operating fingers l2 and a horizontal holding bar l3 which may be operated by a holding magnet M to engage, by means to be described, a selecting finger of an operated vertical select bar to cause a connection to be established at the crosspoint of these bars between associated contacts springs such as shown at 9. It should be understood that this horizontal bar l3 and others like it may extend across all of the switching units in the horizontal row of such switching units. It is evident also that in accordance with the present invention the vertical bars in the switching units of each horizontal row may, if so desired, be arranged in a single continuous horizontal row of vertical select bars without departing from the spirit of the invention. However, it is thought that it will be sufiicient for the clear understanding of the applicants invention to consider in the following description the applicants switching device as consisting of individual switching units W in connection with the other parts as described hereinafter.

The terms vertical and horizontal in regard to frame of switching units will be operative as described if it is rotated through any angle in its plane.

This switching unit ll) may be provided with five vertical select bars operative in two directions in connection with ten horizontal holding bars operative in one direction to establish connections at crosspoints of these two types of bars. The switching units may be arranged in horizontal and vertical rows for operation by a common mechanism in accordance with the applicants invention.

This common mechanism consists, in addition to the above-mentioned holding bars l3, of a vertical column rod i5 for each vertical row of switching units It] having a selecting finger I6 for each horizontal row of switching units and operative by a column magnet Each horizontal row of switching units is provided with a horizontal group rod it operated upon by a horizontal group magnet l3 and each switching unit is provided with an individual horizontal group rod having five fingers 2|. When a column rod such as I5 is rotated counter-clockwise, the fingers It will be placed in a position between associated levers 22 on rods l8 and levers 23 on rods 2|! of the corresponding vertical row of switching units so that, for example, when the horizontal group magnet i8 is operated, the lever 22 will engage the finger It to cause it to engage the lever 23 to rotate the rod 20 in a direction so that the fingers 2| will be moved downwardly. Attached to the lower end of each column rod I5 is a lever 24 to operate on a pin 25 to rotate a horizontal rod 28 common to a vertical row of switching units and located below the lower horizontal row of switching units. This rod 26 is, therefore, rotated on the operation of the column magnet H. To rod 26 are attached five operating fingers 28 which are located slight- 1y above a series of horizontal unit rods 29, 39,

3|, 32 and 33 extending the whole length across the vertica1 rows of switches. The rod 25 extends in front of individual bifurcated projections on the units rods such as, for example, projection 34 on rod 33. That is, there will be provided five such fingers 28 for each vertical row of switching units. These unit rods 29 to 33 may be operated in either direction longitudinally by opposing magnets such as 36 and 3'! as shown for rod 33. The rod 33 may be operated, therefore, towards the left by the magnet 36 operating on its armature attached to red 33 and towards the right by magnet 32 operating on its armature attached to red 33. In a similar manner other magnets, not shown, are provided for oper ating the remaining unit rods in opposite longitudinal directions. Associated with each projection such as 34- is a vertical shaft such as 39 for rod 3i) having a lever 68 registering with a select finger 28 so that when a rod 26 is rotated and this finger enters the bifurcated projection 35, it also will enter a bifurcated extension 42 of the lever 46 and when the corresponding unit rod 30 is moved in one direction or the other, the shaft 39 will thereby be rotated in one direction or the other through the medium of the lever 40, bifurcated extension t2, the bifurcated projection 34 and the finger 223. Each shaft 39 is located opposite a corresponding vertical select bar in each of the corresponding vertical rows of switching units ill and will cause the associated vertical bar H to be rotated in one direction or the other with the shaft 39 through the medium of lever 43 having bifurcated extension 44 and the lever 45 on bar having a bifurcated extension 46, provided the associated finger 2| has been lowered to enter these bifurcations 44 and 46 due to the rotation of the bar 28. Thus a vertical select bar M will be rotated to place the select fingers i2 in position to be operated upon by any horizontal bar i3 of the associated horizontal row of switching units to establish a connection between contacts such as 9 at the corresponding crosspoint of an operated select bar H and holding bar it. It should be understood that each holding bar i3 may be provided with suitable T-shaped control levers such as 4-! each for the purpose of operating either of two sets of crosspoint contacts.

The details of the crosspoint contact operating arrangements are shown by Fig. 3. The crosspoint contacts 9 comprise, for illustration, three fixed contact springs formed from horizontal members (if! and three movable springs 6| suitably mounted on, but insulated from, the frame of the switching unit. Two sets of these crosspoint contacts are arranged to be operated by a single lever All affixed to the holding bar l3. The lever 4? terminates in an operating head 5|. Each set of contacts El has a contact card 53 of suitable insulating material engaging the movable springs of the contact assembly. The operating finger it is normally slightly above and between the contact cards. If the select bar ii is rotated counter-clockwise, the operating finger will be placed over the lefthand contact card so that upon subsequent rotation of horizontal bar |3 to move the head 5| downwardly, the latter will engage operating finger i2 to cause it to engage the contact card 63 and close the left-hand contacts 5. Had the vertical select bar H been rotated clockwise, the right-hand contacts would have been similarly closed upon operation of horizontal bar Should horizontal bar l3 be operated with vertical select bar H in its normal position, neither contacts would be closed inasmuch as the select finger l2 would-not be in position to engage the contact cards of either contact assembly. The bottom part of head 5! may have a recession at its center as shown so that the select finger l2 will not be engaged by head when this finger is normal. It will be seen, therefore, that a single lever ll will selectively operate either of two contact assemblies, depending upon the direction the vertical select bar M has been rotated to position the select finger.

In systems where switching devices of type may be employed, so--called off-normal contacts are generally required. To provide such contacts for operation each time a connection is made at a crosspoint in any of the switching units an arrangement such as shown by 3 m employed. A set of oil-normal contacts are provided for each vertical row of crosspoints in each switching unit with an operating rod individual thereto, said rod extending vertically alongside the ten sets of crosspo-ints in the row. A collar St is provided on this rod for set of crosspoints in the row and is adapted to be engaged by bracket attached: to the contact card so that upon downward movement of any contact card in the row incident to closure of the corresponding crcsspoints, the rod will be moved downward to actuate the contacts 54. The rod 53 'may, of course, moved by closure of any particular cro contacts without affecting the other cros in the corresponding row'since the collars 6d are adapted to move free of brackets 65 of the other crosspoints.

While closure of three sets of contacts are indicated by Fig. 3 upon operation of a particular crosspoint, it will be understood that other numbers of contacts and contact arrangements they be employed. Likewise, while only two chimermal contacts are shown for illustration, other numbers of such contacts may be used. Also, the off-normal contacts comprise me break or transfer types of contacts, or ccmbina;-..ons thereof. as required circuit uses of the device.

Similarly, there may be provided oiimormal contacts for each select bar ii. In this case as the select bar 2 l is rotated either of two d ections to select associated cross-p nt contacts, two sets of oil-normal contacts will be provided, one set for each vertical row of springs. This arrangement of (id-normal contacts for each select bar l i may be ShOY n that each bar i! may be provided with lever 1-5! which acts on oil-normal contacts when l l is rotated counter-clockwise and which acts on off-normal contacts Ell when bar it is rotated clockwise. It is. of course, evident that other off-normal. contact arrangements be provided as desired for those operable by bar ii, and also for any or all of the magnets in these switching devices to operate when the magnets are energized. It seems unnecessary to illustrate such oihncrrnal contacts for the magnets the drawings.

It is to be understood that all of the operable select elements described be provided wit.

to the of the which one their operation, they will returned to t. 1 normal position by said spring means.

With these general descriptions of the operating mechanisms that may be employed to carry out the applicants invention, a description will now be made of a specific arrangement of switching units It and a common mechanism for operating contact springs in any one of said switching units by means of said common mechanism. To this end, Fig. 2 has been prepared to show in diagrammatic form an organization of switching units suitable for this purpose. In this figure two switching units Hill and till have been shown in one horizontal row and below this two other switching units m2 and M3 have been shown of another horizontal row. It may be assumed, for example, that these switching units form part of a system having a capacity of seven hundred line connections which would require seventy ten-by-ten switching units, that is, these units may be arranged in seven vertical rows and ten horizontal rows with, for example, switching units and mi being the first and second units in the upper or irst horizontal row of seven units, and switching units Edi: and M3 being the first and second units in the tenth or lower horizontal row of seven units. That would place units ldil and 592 in the first of seven vertical rows of units and units it'll and its in the second of the seven vertical rows of units with each vertical row containing ten units. If an arrangement was made to establish con-- nections between seven hundred lines and one hundred trunks by the aid of ordinary crossbar switches there would be required seven hundred holding magnets and four hundred select magnets, if the crossbar switches were arranged under present practice as follows: For example, there may be employed in each of ten horizontal rows three crossbar switches having twenty holdmagnets and ten select magnets each and one crossbar switch having ten holding magnets and ten select magnets or eleven hundred magnets in all. On the other hand by the use of this common mechanism an arrangement for the establishing of seven hundred connections would only require one hundred holding magnets, that is, ten holding magnets for each horizontal row of seven switching units, ten unit magnets located at the bottom of the ten horizontal of switching units, ten horizontal group magnets one for each horizontal row of units, and seven column magnets one for each vertical row of units, making a total of one hundred and twentyseven magnets, which a considerable saving in operating magnets mechanisms for these switching units over those ordinarily required. If, therefore, the switching units are arranged in the manner shown in Fig. 2, the selecting of any of the contact springs at any crosspcint in any one of these seventy switching units may be accomplished as follows: For example, the column magnet i? may be operated. This would select the first v rtical row of ten switching units by placing the it on the rod ill in position to be operated upon to cause the operation of any of the horizontal rods 25? to select the particular switching unit in the column of switching units. If it is ti assumed that the horizontal group magnet ill operated rotate the corresponding group rod ill this it would, through lever it lever cause the operation of the correspo ing group rod 2!! to cause this red to place the i is ill in position to be operated upon for the selection of a vertical bar 5! in switching unit H32. Thus the operation of group magnet will select the switching unit M2 the first column in which are located the contacts to be operated. If new one of the unit magnets, for example, 31 is operated, it will, through the medium of the finger 28, previously moved by bar as on the operation of the column bar IE to its operated position between the projections lid of unit rod 33 and between the projections 52 on the lever 60 of the shaft 39, cause the shaft 39 to be rotated in a counter-clockwise direction. Shaft 3:! causes the rotation in the same direction of bar H of switching unit Hi2 through the lever 43 and its extension 44, finger 2i and lever 35 and its extension iti. Rotation of bar ll will, therefore, select for subsequent individual selection the con tacts in the corresponding vertical row of switching units use that are opposite the bar H when it is rotated in this direction as controlled by shaft Had the unit magnet 38 been operated, the unit rod 33 would have been shifted in the opposite direction and thus cause bar i i to be rotated in the opposite direction for selection of contacts in the adjacent vertical row in switching unit Hi2. If now the holding magnet M is operated to rotate bar iii, a finger iii of bar ll will be engaged by a head of an operating projection ll on bar l3 and the contact springs at the crosspoints of bars 63 and H will be operated in the manner described above. The holding magnet i l will, of course, hold this connection established while the other magnets l'i, is,

31 and associated rods will be released and re- 0 stored by their springs, not shown, to their normal positions for use in the establishing of connections in this or in any other switching units.

It should be understood that the invention is not confined to the particular number of switch ranging the switching units in horizontal rows I of seven switching units each and ten such horizontal rows for a seven hundred line capacity, switching units may be arranged in five horizontal rows with each horizontal row containing seven switching units each unit comprising ten vertical select bars running across twenty holding bars, thus making a saving of five group magnets is and the associated rods ill and ill of the common mechanism and yet have the switching device retain the seven hundred line capacity. Likewise, the horizontal rods 21 individual to each switching unit may be eliminated by providing their select fingers on rod 53 so that upon operation of magnet it all such fingers will be positioned to enable any select bars in the corresponding horizontal row of switching units to be operated by one of shafts 323. This would eliminate the need for column rods l5, and their magnets ll would be needed merely to operate select bars to. It also will be seen that the select fingers 52 may be mounted on shaft 39 which would eliminate the necessity of individual select bars H, the horizontal group magnets is, rods l5, l3 and 2t and the elements associated therewith. The magnets ll would in this case, also, be needed only to actuate select rods 25. t is also apparent that magnets individual to each vertical shaft may be used to rotate said shafts individually rather than employing unit rods 29 to 33 and operating magnets therefor. Various combinations of the above and other modifications of the details of the arrangement may be made within the spirit and scope of the invention.

What is claimed is:

1. In a switching mechanism, a plurality o! crossbar switching unit arranged coordinately in horizontal and vertical rows, a plurality of select bars for each unit arranged in one coordinate direction, a plurality of holding bars arranged in the other coordinate direction and cooperating with said select bars, contacts at each intersecting point of said select and holding bars in each unit, means for establishing connections between the contacts at any point by the operation of a corresponding select bar and a corresponding holding bar, a mechanism including mechanical elements extending along and operatively associated with said units for selecting and mechanically operating a select bar in any of said units to the exclusion of other units, and means for operating a holding bar coordinately associated with the operated select bar to operate the contacts at the intersecting points of said select and holding bars.

2. In a switching mechanism, a plurality of crossbar switching units arranged coordinately in horizontal and vertical rows, a plurality of select bars for each unit arranged in one coordinate direction, a plurality of holding bars arranged in the other coordinate direction and cooperating with said select bars, contacts at each intersecting point of said select and holding bars in each unit, means for establishing connections between the contacts at any point by the operation of a corresponding select bar and a corresponding holding bar, a mechanism common to said units including mechanical elements coordinately arranged along, and operatively associated with, said units for selecting any particular one of said units and selecting and mechanically operating a select bar in said selected unit, and means for operating a holding bar coordinately associated with an operated select bar to operate the contacts at the intersecting point of said select and holding bars.

3. In a switching mechanism, a plurality of cross-bar switching units arranged coordinately in horizontal and vertical rows, a plurality of select bars for each unit arranged in one coordinate direction, a plurality of holding bar arranged in the other coordinate direction and cooperating with said select bars, contacts at each intersecting point of said select and holding bars in each unit, means for establishing connections between the contacts at any point by the opera tion of a corresponding select bar and a corresponding holding bar, a select rod for each unit operable to condition the select bars of its unit for selection and operation, a mechanism common to all of said units for operating the select rod of any unit to the exclusion of the select rods of all other units, a second mechanism common to all of said units functioning through an operated select rod for selecting and operating a select bar conditioned by said select rod, and means for operating a holding bar coordinately associated with an operated select bar to oper ate the contacts at the intersecting point of said select and holding bars.

4. In a switching mechanism, a plurality of cross-bar switches arranged coordinately in horizontal and vertical rows, a plurality of select bars for each switch arranged in one co-ordinate direction, a plurality of holding bars arranged in the other coordinate direction and cooperating with said select bars, contacts at each intersecting point of said select and holding bars in each switch, means for establishing connections between the contacts at any point by the operation of a corresponding select bar and a corresponding holding bar, a set of group select rods with each rod individual to a vertical row of switches, a set of group rods with each rod individual to a horizontal row of switches, means for operating said group select rods, means responsive to the coordinate operation of one of each of said two sets of group select rods for conditioning for operation the select bars in the switching corresponding to the intersecting point of said two operated group select rods, means including means common to all of said switches for oper ating a select bar among those conditioned, and means for operating a holding bar coordinately associated with an operated select bar to operate the contacts at the intersecting point of said select and holding bars.

5. In a switching mechanism, a plurality oi cross-bar switches arranged in horizontal and vertical rows, a plurality of vertical select bars for each switch, a plurality of horizontal holding bars coordinately operative with said select bars, contacts at each intersecting point or said vertical and horizontal bars in each switch, means for establishing connections between the contacts at any point by the operation of a corresponding vertical select car and a corresponding holding bar, a vertical shaft for each vertical row of select bars, means including means common to all of said switches for operatively associating the select bars of a particular switch with their respective shafts, means to operate a particular one of said last-mentioned shafts to operate the select bar operatively associated therewith, and

means for operating a horizontal holding bar coordinately associated with an operated select bar to operate the contacts at the intersecting point of said select and holding bars.

6. In a switching mechanism, a plurality of cross-bar switches arranged in horizontal and vertical rows, a plurality of vertical select bars for each switch, a plurality of horizontal holding bars coordinately operative with said select bars, contacts at each intersecting point of said vertical and horizontal bars in each switch, means for establishing connections between the contacts at any point by the operation of a corresponding vertical select bar and a corresponding holding bar, a switch select rod for each switch, means including means common to said switches for operating a switch select rod, a vertical shaft for each vertical row of select bars extending in operative relationship with the switch select rod of each switch in the corresponding vertical row of switches, a group of select magnets common to all of said switches, means controlled by said means for operating the switch select rods to operatively associate the magnets and the vertical shafts to operate a shaft by a magnet, means cooperating with an operated switch select rod to operate a select bar in the switch corresponding to said operated switch select rod in response to the operation of a shaft, and means for operating a horizontal holding bar coordinately associated with the operated select bar to operate the contacts at the intersecting point of said select and holding bars.

7. In a switching mechanism, a plurality of cross-bar switches arranged in horizontal and vertical rows, a plurality of vertical select bars for each switch, a plurality of horizontal holding bars coordinately operative with said select bars, contacts at each intersecting point of said vertical and horizontal bars in each switch, means for establishing connections between the contacts at any point by the operation of a corresponding vertical select bar and a corresponding holding bar, a switch select rod for eachswitch, a vertical group select rod individual to each vertical row of switches, means for operating each of said vertical group select rode, a horizontal group select rod individual .to each horizontal row of switches, means for operating each of said horizontal group select rods, means responsive to the operation of a vertical group select rod and a horizontal ,group select rod for operating the switch select rod corresponding to the intersecting point of said vertical and horizontal group select rods, a vertical shaft for each vertical row of select bars extending in operative relationship with the switch select rod or each switch in the corresponding vertical row of switches, means including a set of magnets common to all of said switches cooperating as determined by an operated vertical group select rod to operate a shaft of the vertical row of switches corresponding to the operated vertical group select rod,.means operated by said shaft cooperating with the operated switch select rod for operating a vertical select bar in the switch corresponding to said last-mentioned switch select rod, and means for operating a horizontal holding bar coordinately associated with an operated select bar to operate the contacts at the intersecting point of said select and holding bars.

8. In a switching mechanism, a plurality of cross-bar switches arranged in horizontal and vertical rows, a plurality of vertical select bars ior each switch, a plurality of horizontal holding bars coordinately operative with said select bars, contacts ateach intersecting point of said vertical and horizontal bars in each switch, means for establishing connections between the contacts at any point by the operation of a corresponding vertical select bar and a corresponding holding bar, a vertical group rod individual to each vertical row of switches, means for operating each of said vertical group rods, a horizontal group rodfor each horizontal row of switches, means for operating each of said horizontal group rods, means responsive to the operation of a vertical group rod and a horizontal group rod for conditioning for operation the select bars in the switch corresponding to the intersecting point of said two operated group rods, a group of vertical shafts for each vertical row of switches with each shaft corresponding to a vertical select bar in each switch in said row, a group of select magnets for all of said switches, means responsive to the operation of a vertical group rod for operatively associating the group of shafts corresponding to this vertical group rod with said magnets whereby the operation of a magnet will result in the operation of a shaft, means functioning through said means for conditioning a set of select bars to operate one of said select bars in response to the operation of the shaft corresponding there-,

to, and. means for operating a horizontal holding bar coordinately associated with an operated select bar to operate the-contacts at the intersecting point of said select and holding bars.

9. In a switching mechanism, a plurality of cross-oar switches arranged coordinately in horizontal and vertical rows, aplurality of select bars for each switch-arranged-in one coordinate direction, a plurality'of holding bars arranged in the other coordinate direction and cooperating with said select bars, contacts at each intersecting point of said select and holding bars in each switch, means for establishing connections between the contacts at any point by the operation of a corresponding select bar and a corresponding holding bar, means common to said switches including a group of vertical and horizontal rods for conditioning for operation a particular switch corresponding to the intersecting point of an operated vertical and an operated horizontal rod, an operating magnet for each of said rods, a set of shafts, means including means common to said switches for operating a shaft, means responsive to the operation of a shaft for operating a select bar in said conditioned switch and means to operate a holding bar coordinately associated with an operated select bar to operate the contacts at the intersecting point of said select and holding bars.

10. In a switching mechanism, a plurality of horizontal rows of vertical select bars, a plurality of horizontal holding bars common to each row for coordinate operation with said select bars in corresponding rows, contacts at each intersecting point of said vertical select bars and horizontal holding bars, means for establishing connections between the contacts at any intersecting point by the operation of a corresponding vertical select bar and a corresponding horizontal holding bar, a mechanism including mechanical elements extending along and operatively associated with said rows of vertical select bars operable to select and mechanically operate any vertical select bar in any of said rows, and means for operating a horizontal holding bar coordinately associated with an operated vertical select bar to operate the contacts at the intersecting point of said select and holding bars.

11. In a switching mechanism, a plurality of horizontal rows of vertical select bars each operable in two directions, a plurality of horizontal holding bars common to each row coordinately operative with said select bars in corresponding rows, a pair of sets of contacts at each intersecting point of said vertical and horizontal bars, means for establishing connections between the contacts of one of the pair of sets of contacts at the intersecting point by the operation of the corresponding vertical select bar in one direction and the operation of a corresponding holding bar and for establishing connections between the contacts of the other of the pair of sets of contacts by the operation of said last-mentioned select bar in the other direction and the operation of said last-mentioned holding bar, means including a mechanism with mechanical elements common to, and extending along, said rows of select bars for selecting any select bar and mechanically operating it in either of its operable directions, and means for operating a holding bar coordinately associated with an operated select bar to operate the set of contacts of the pair at the intersecting point of said select and said holding bars predetermined by the direction in which said select bar has been operated.

12. The method of selecting and operating particular sets of contacts in a bank of coordinately arranged switches each with a plurality of coordinately arranged contacts which consists in mechanically conditioning a row of switches along one ordinate for selection, effecting a mechanical operation along the other ordinate for conditioning the switch corresponding to the crossing of said ordinates for selections within said switch, effecting a mechanical operation along the row of switches corresponding to said first ordinate to effect the selection and conditioning for subsequent operation of a row of contacts in the direction of this ordinate within the conditioned switch and effecting a mechanical operation along the other ordinate within said switch to effect the selection and closures of the contacts corresponding to the intersection of said last-mentioned ordinate and the row of selected contacts.

13. The method of selecting and operating particular sets of contacts in a bank of switches arranged coordinately along ordinates M and N each with a plurality of contacts arranged coordinately along ordinates m and n, in which ordinates m and n are parallel respectively to M and N, which consists in mechanically conditioning the switches along ordinate M for selection, effecting a mechanical operation along ordinate N for selecting the particular switch of those conditioned which corresponds to the intersection of these two ordinates and conditioning said selected switch for selections within it, effecting a mechanical operation along the row of switches corresponding to ordinate M to effect the selection within the conditioned switch of a row of contacts along the m ordinate and effecting a mechanical operation along the n ordinate within said switch to select and close the set of contacts corresponding to the intersection of said lastmentioned ordinates.

14. The method of selecting and operating particular sets of contacts coordinately arranged in vertical and horizontal rows of groups in a bank which consists in performing mechanical operations along the vertical and horizontal ordinates for conditioning the sets of contacts of a group of contacts corresponding to the intersecting point of said ordinates for subsequent selection, performing a mechanical operation along the vertical ordinate for conditioning particular sets of contacts in said conditioned group for subsequent operation and performing a mechanical operation along the horizontal ordinate within said group for operating the set of coordinated contacts corresponding to the intersecting point of said lastmentioned ordinates.

15. A cross-bar switch comprising a plurality of primary circuits, a plurality of secondary circuits arranged transversely to and intersecting the primary circuits, contacts at each intersecting point operative to interconnect the primary and secondary circuits corresponding to said intersecting points, a select bar individual to each primary circuit momentarily operative to condition the contacts corresponding to its primary circuit for subsequent operation, a holding bar individual to each secondary circuit, means responsive to the operation of a holding bar while a select bar is operated to effect operation of the particular contacts of those conditioned for operation corresponding to the secondary circuit of last said holding bar and to maintain said contacts operated subsequent to the restoration of said select bar, means to operate any select bar momentarily, means to operate and maintain operated any holding bar, oil-normal contacts corresponding to each primary circuit and means to operate the oil-normal contacts of any primary circuit when that primary circuit is interconnected with any secondary circuit and to maintain them operated following the restoration of the operated select bar.

16. IA cross-bar switch comprising a plurality of primary circuits, a plurality of secondary circuits arranged transversely to and intersecting the primary circuits, contacts at each intersecting point operative to interconnect the primary and secondary circuit corresponding to said intersecting points, select bars momentarily operative individually to condition the contacts corresponding to any primary circuit for subsequent operation, a holding bar individual to each secondary circuit, means responsive to the operation of a holding bar while a select bar is 0perated to efiect operation of the particular contacts of those conditioned for operation corresponding to the secondary circuit of said last holding bar and to maintain said contacts cperated subsequent to the restoration of said select bar, means to operate any select bar momentarily, means to operate and maintain operated any holding bar, cit-normal contacts corresponding to each primary circuit and means to operate the off-normal contacts of a particular primary circuit in response to the actuation of any contacts for interconnecting that primary circuit with a secondary circuit whereby the elf-normal contacts are controlled by the holding bar of the interconnected secondary circuit.

17. A switching mechanism including a plurality of cross-bar switches, a plurality of sets of contacts in each switch and means to select and operate any set of contacts in any switch, last said means including a plurality of magnets the total number of which is less than one-tenth the total number of sets of contacts in said switches.

18. A switching mechanism including a plurality of lines, a plurality of trunks in number smaller than the number of lines, off-normal contacts individual to each line, a plurality of crossbar switches, a plurality of sets of contacts arranged in intersecting rows in each switch operative to selectively interconnect the lines and trunks, means common to said switches to select and operate the contact set at any erosspoint in any switch, last said means including operating magnets in number less than the number of lines, and means operative in response to the operation of a set of crosspoint contacts for actuating the off-normal contacts corresponding to the line interconnected with a trunk thereby.

JUDSON OD SHEPHERD.

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