US1633118A - Bank and trunk cable multipling system - Google Patents

Description

June 21,1927.

- 1,633,118 H. B. MGELYEA BANK AND TRUNK CABLE MULTIPLING SYSTEM Original Filed Dec. 18, 1922 '7 S'heet's-Sheet 1 um w km* June 21, 1927. 1,633,118

H. B. MCELYEA BANK AND TRUNK CABLE MULTIPLING SYSTEM Original Filed Dec, 18, 1922 '7 Sheets-Sheet 2 H E11-:leg E HQE IgE-E1 BANK TRUNK CABLE MULTIPLING SYSTEM H. ABL MOELYEA v rsheets-:sheet 5 Original Filed Dec. 18, 1922 2;/

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June 21 1927.

H. B. MELYEA BANK AND TRUNK CABLE MULTIPLING SYSTEM s s I i @iw I 411 @@l l H a I' @IH-Pl@ @@@i CEI@ I l: I @E originalilaa Dec. 18. 1922 '7 Sheets-Sheet 6 June 21, 1927. 1,633,118

H. B. McELYEA BANK'AND TRUNK CABLE MULTIPLI'NG SYSTEM Original Filed Dec. 18.- 1922 7 Sheets-Sheet 7 Harley B HEgea Z. M HUT Patented June 2l, 1927.

s'ni'resA f 1,633,118 PATENT OFFICE.

HARLEY B. MCELYEA, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,'

TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION F DELA- waan.

BANK AND-TRUNK CABLE MULTIPLING SYSTEM.

.Application led December 1.8, 1922, Serial No. 607,485. Renewed December 4, 1928.

The present invent-ion relates to bank and trunk cable-multipling systems in general, that is, systems for multipling to ethervthe bank cables of selector switches an the trunk 5 cables leading to the switches in the next series in automatic telephone systems; and the main object is the production of an improved system' ofthe above named type, whereby the 'bank and trunk cables in an automatic telephone system may be readily Inultipled together in any desired manner, and may be later multipled together readily in any other manner as the necessity arises. Another object, incidental to the carrying out of the main object, is the production of a new and improved distributing frame for use in connection with the improved multipling system which may be manufactured cheaply; which is simple and easy to install;-

and which permits the bank cables to be connected together in either large or small groups, or in any one of a large number of different combinations, with a minimum amount of labor.

It is common practice in automatic telephone exchanges employing step'by step selector switches of the vertical and rotary type to place the switches side by side in ,shelves or rows of ten or twenty switches 3W each, and to multiple the bank contacts of adjacent switches together in groups of ten, the banks being multipled so that corresponding contacts are wired togetherl throughout the ten switches of any one group. A plurality of switches with their banks so multipled are known in the art as a .shelf. It is also common practice to multiple a trunk cable to corresponding levels ina plurality of shelves of switches 40 in order to secure the correct amount of traffic fol` the switches to which the trunlt cable extends.

It is very evident that when the abovenamed practice is followed, some sort of connecting frame or terminal assembly must be provided if the Inultipling wires are not to become a hopeless tangle. According to the practice which has been commonly followed heretofore, two suitably constructed parallelogram shaped mounting frames are placed in an upright position about two feet or more apart and parallel to each other. The switches are placed on these frames in five or six horizontal rows with one row 95 above another and with two shelves of ten switches each in each row. A connecting cable, or bank cable as it is called,- connects the banks of each shelfof switches'to the terminal assembly frame which is placed 1n an upright position across one end of the space between the mount-ing frames. The word bay is commonly used to mean a group of shelves of switches collectively that are connected by their bank cables wit-h a common terminal assembl frame.

On the terminal assemb y frame'the bank cables are connected to flat terminals which are secured in long strips of insulating ma.- terial laid on the'horizontal supports of the terminal assembly frame. The multipling together of adjacent shelves is taken care of by so-called up and down multiples. An up and down multiple, it ma be stated, comprises two flat terminal strlps, similar to the terminal strips to which the bank cables are connected, and a connecting cable.

When one shelf is to be multipled withanother shelf,` its terminals and one set of terminals of an up and down multiple are soldered together. T he terminals of the other shelf are secured in like manner to the terminals of the other strip of the same up and down multiple, and also to still another multipling strip if a third shelf is to be included in the multiple. This process is repeated until the desired number of shelves are multipled together. vThe number of shelves, of course, that are multipled together is determined by the traffic conditions and often varies considerably' among the different levels.

The outlets for a shelf or for a group of multiply connected shelves are provided by trunk cables which also are terminated on the supports in lat terminals. These terminals are bent into engagement with and soldered to the terminals of the desired shelf or to the terminals of one shelf of a multiply connected group of shelves. v

While the foregoing method of multipling together the shelves and of providing outlets for the traflic has been successfully used for a number of years, .it has been found to be inflexible as regards traffic changes which occurmore or less frequently, and also as regards additions which 'involve regrouping and rearranging. These facts and others of varyin importance have presented themselves an have given rise to the development of a distributing frame te rethe upper part of the frame.

place the oldy terminal assembly frame. This distributing frame is exceedingly fieX- ible as regards traiiic changes and as regards regrouping necessitated by additions which are likely to occur from time to time.

When the new distributing frame is used, it occupies the same relative position as the old terminal assembly frame, and comprises essentially bank cable terminal blocks which are arranged in horizontal strips and occupy the greater part of the space on the frame, and trunk cable terminal blocks which also are arranged in horizontal strils and occupy Ahe terminals in both the bank cable terminal blocks and the trunk cable terminal blocks are of the pin type.

The up and down multiplin or the multipling between adjacent she ves, is taken care of by bare jumper wire which extends vertically along the front of the distributing frame, and which is soldered to corres onding contacts on the various blocks whic are to be multipled together.

The rear end of each bank cable terminal block pin has two notches instead of one. The bank cable wire is fastened to the pin at one notch, leaving the other notch free so that a jumper wire can be fastened to the pin to connect the multipled group with an outgoing cable to which access is gained through one of the trunk cable terminal blocks in the upper part of the frame.

Referring now to the drawings comprising Figs. l-lO, inclusive they show various views of the new distributing frame, and also serve to give an understanding of a few of the many ways in which the improved distributing frame can be used.

Figure l is a View, drawn to a considerably reduced scale, showing a mounting frame fully equipped with twelve Shelves of switches and also an edge view of the new distributing frame, which frame serves as a distributing frame for the switches shown, and also for an equal number of switches similarly located on a mounting frame behind the one shown and parallel to it.

Figure 2 is a front view of the improved distributing frame and shows the bank cable terminal blocks and the trunk cable terminal blocks in place, the trunk cable terminal blocks being those in the upper section, and the bank cable terminal blocks being those in the lower section.

Figure `3 is drawn to a larger scale than Figs. 1 and 2, and is a View of the section of the distributing frame `which is separated from the major part by the dotted line 3 3, Fig. 2.

Figure 4 is a rear view of the section I shown in Fig. 3 with one bank cable 3l and one trunk cable 55 shown in place.

Figure 5 is a view of the improved distributing frame and the rst tive vertical rows of switches on either side, as seen from the top, with the frame-work shown above the dotted line 5-5, Fig. l, removed in order to give a clearer view.

Figure 6 is a top view of a bank cable terminal block and is, for example, one of the blocks shown in the strip 53, Fig. 3. This block is drawn to actual dimensions.

Figure 7 is a view showing more clearly the construction of a single terminal, such as one of the terminals in the block shown in Fig. 6. Figure 8 is a diagrammatic view of the improved distributing frame, and shows in one particular situation the number of shelves which are multipled together on the variouslevels and are jumpered to the desired trunk cables.

Figure 9 is a diagram of a second distributing frame interconnected with the first by tie cables.

Figure 10 is a detailed diagram and shows an alternative method of connecting up the fourth level of bank contacts at the distributing frame shown in Fig. 8.

While the improved distributing frame vmay be used in connection with any desired automatic switch, the switches shown in Figs. l and 5 are assumed to be of the type described in connection with and shown in Fig. 62 of the illustrations in the second edition of Automatic Telephony, a book by Smith & Campbell, published by McGraw- Hill Book Company, Inc., New York. A photograph of selectors covered and mounted as indicated in Figs. 1 and 5 is shown in Fig. 98 of the above mentioned book.

In view of the illustrations above referred to, it is considered unnecessary to show the switches in any detail and, consequently, they are indicated only generally. However, the shaft and wipers of switch 20, Fig. l, and also of the switch in the lower left-hand corner of the same figure, are indicated to give some slight idea of how the switches look.

Referring now particularly to Figs. l-7, inclusive, the construction of the improved distributing frame and its position as regards the associated switches and switch banks will be explained. The frame on which the switches shown in Fig. l are mounted, comprises essentially three suitably braced uprights, and the interconnecting cross-bars on which the switches are hung. Of the three switch supporting uprights, only two, 46 and 47, are visible. The other one is directly behind the upright 45 and in line with the uprights 46 and 47, the uprights 45 and 48 being located far enough forward to allow the front part of the switches to come behind them so that doors may be provided if desired. The relative positions of the uprights may be readily ascertained upon reference to Fig. 5 which,

' Fig. 1 for example, l

as before stated, is a top view of the distributing frame and the first ivevertical rows of switches.

The distributing frame, seen most clearly in Fig. 2, comprises essentially the uprights 48 and 49 and the strips of terminal blocks which are secured between them.

The switch mounting frame shown in Fig. l, the one behind it, and the distributingy frame are bound together at the top by the four strips of heavy angle irons 41-44, inclusive.

Taking the top row of switches shown in the irst ten switches, 1l0, inclusive, comprise a shelf and their banks are accordingly multipled together and are connected with the distributing frame by the cable 31.

The banks of the shelf of switches comprising switches 11-20, inclusive, are connected with the distributing frame by the cable 32. The other shelves of switches below are similarlyconnected as is indicated by the other cables.

As shown,

- shelves in the top row of Fig. 1 lead to the irst two bank cable strips 53 and 54, Fig. 2; the -two bank cable strips immediately ybelow are left for the cables coming in from the other side of the distributing frame; and the next two shelves of switches from the top, Fig. 1, are associated with the n fifth and sixth bank cablestrips, etc. This arrangement, however, is merely arbitrary and may be deviated from as desired. For example, the arrangement may be such that the two top shelves, Fig. 1, may be cabled to the first and third strips, leaving the second and fourth strips for cables coming in from the other side of the distributing trame.

The four strips located at the top of the distributing frame, Fig. 2, lrepresent terminal blocks to which the trunk cables which form outlets for the trac from the associated switches are connected. As shown,

- there are five blocks in each strip, making `called six-pin blocks instead o the threepin blocks shown.

The conductors of the trunk cable are connected to the lower end of the trunk block terminals as is indicated by the position of cable 55, Fig. 4, and when.the cables .are

connected, each set of three terminals represents one three-conductor trunk.

Referringnow particularly to Figs. 3, 4. and 6, it will be noted that the terminal blocks of a bank cable strip are secured bethe bank cables Jfrom the two irons 48 and 49, as can be seen most clearj 1y in Fig. 4.

Although anyone of a number of dierent methods may e used in placing the pins in thebank cable terminal blocks, vsuch as using sectional .blocks and blocks with holes in them, etc., the preferred construction is that the bank cable terminal blocks are molded composition, such as hard-rubber for example, and that the blocks are molded around the terminals.

It will be noted, upon reference to Figs. 3 and 4, that the terminals in a'bank cable block are arran ed in' ten groups of three,

one terminal a ove the other. However, the terminals are so staggered that no one terminal is directly above any other terminal in the same block, but is directly above the corresponding terminal in the block below. This permits any desired number of con tacts located in a vertical line Ato be multipled together in a neat workmanlike manner with uninsulated wire. The front of each of the terminals, ,as is seen best in Figs. 6 and 7, is grooved so as to allow the bare jumper wire to be centered on the terminal without diiiculty, and also to facilitate the soldering of the jumper wire to-/thejerminal A few of the bare jumper wires are shown in place and soldered in Fig. 3.

Referring now particularly to Figs. 4, 6, and 7 it will be noted in Fig. 4 that the conductors of the bank cable 31 are connected to theterminals at the rear of the bank cable terminal blocks. As shown in Figs. 6 and 7 two sets of notches are provided for each terminal. One setl of notches is for the bank cable which is placed on first, and which is connected to the notches nearer the block, and the other set of notches is for the jumpers which are run from certain of the bank cable blocks to the correct trunk cable block in the upper part of the distributing frame. The jumpers are passed up from underneath through the desired one of the five holes in the spreading strip such as the spreading strip 61, which is to be seen most clearly in Fig. 6. The ends of two jumpers 74 and 7 5 are shown in Fig. 4. The remaining part of the jumpers cannot be shown in Fig. 4 for the reason that they pass back through jumper rings in a manner similar to the jumpers shown in Figs. 1 and 5.

It may be seen that when the new distributing frame is used, as many shelves as debank cable sired may be grouped together by multipling the corresponding terminals on the front of ythe distributing frame with bare Wire, and that the group thus formed can be connected to the desired trunks by means of jumdpers. With this arrangement, the up and multiple on the front of the distributing frame may be varied so as to include more or less shelves of switches .as the occasion demands, and the jumpers which connect the groups of shelves to the trunk cables may be changed accordingly at will.

Referring now particularly to" Fig. 8, which as before stated, is a diagrammatic view of the improved distributing frame, the associated shelves of switches are indicated by the thin horizontal rectangles on either side, which are lettered A to L, inclusive, and A' to L', inclusive. The heavy lines which are below the rectangles representing the switches, represent the'banks of thev switches, and the lines which connect tne switch banks with the horizontal rows of short heavy lines located in the middle of the drawing represent the bank cables.

One short heavy line in any horizontal row to which abank cable connects indicates one complete bank cable terminal block, and is connected by the bank cable to one level of contacts in the associated shelf of switches. The bank cables, of course, are so fanned out and connected, that the first block in each strip is connected with the first level of bank contacts and so on to the tenth block, which is connected with the tenth level of bank contacts as is indicated by numerals placed under the vertical rows of blocks at the bottom of the drawing. The order in which the shelves of switches are connected to the strips of terminals in Fig. 8, it may be stated, is the same as is indicated in Fig. 2 by the letters A-L, inclusive, and A-L, inclusive, placed opposite the terminal strips. Regarding the trunk cable terminal blocks shown above the bank cable terminal blocks, it may be said that these blocks are connected up by trunk cables to the switches in the proper groups in such a manner that the group connected with the first vertical row of blocks is group No. 1, and so on in order corresponding with the bank levels which are underneath. This arrangement, however, is purely arbitrary and may be varied to suit the requirements of any particular installation. It will be noted that ten vertical rows of trunk cable terminal blocks are indicated, while only five vertical rows are shown in Fig. 2. The reason for this seeining discrepancy is that one short heavy line in Fig. 8 indicates only half of. one complete block as shown in Fig. 2, because one block contains twenty sets of contacts which is suiiicient for two levels. Also, it will be noted that there are more horizontal rows of .Short horizontal lines indicating trunk cable terminal blocks than there are strips of blocks indicated in Fig. 2. This is due to the fact that when as many blocks are needed as are shown equipped in Fig. 8, some of the blocks shown in Fig. 2 must be provided with six terminals in a set instead of three, in which case that block is indicated by twice the usual number of short heavy lines. No attempt'l has been made to indicate which of the strips of blocks shown in Fig. 2 are equipped with six terminals in a set for the reason that any strip may be so equipped without altering the scheme.

It will be noted that certain of the spaces in the section allotted to the trunk cable terminal blocks are left blank. This is done because there are no cables at present on these blocks. However, the terminals may or may not be on the blocks at those places, depending upon whether or not there is a likelihood that they will be needed in the future.

The two upper rows of heav short lines indicate the blocks to which tie cables are connected, so as to link the distributing frame shown in this drawing with the one shown in Fig. 9, for a purpose that will appear more fully as the description prograsses.

For the purpose of this description, it will be arbitrarily assumed that the distributing frames shown in Figs. 8-10, inclusive, are serving second or thousands selectors in one oiiice of a multi-cnice system with an ultimate capacity the switches shown in Figs. 8 and 9 are required to select any one of a plurality of groups of a thousand lines each. It will be assumed further that the traiiic differs considerably amongst the various thousand line groups, and that the ninth. and tenth levels are dead :for the reason that the correspondinggroups are left blank.

It will be assumed further that if the trailic were equally divided amongst the eight working levels, seven shelves multipled together on the form a group of the proper size and with the proper margin of safety to furnish traffic on any one level for ten trunks. Since, however, according to a previous assumption, the load is not equally divided amongst the eight working levels, the arrangement is varied so that we have insome cases more than seven shelves multipled together on one level and less than seven multipled together on another level. For example, on the first and sixth levels, where the traliic is relatively light as compared with the other levels, eight shelves can be multiplied together and jumpered to one trunk cable as is indicated by the bundles of jumpers represented by the three lines bearing the reference characters 27 9-281, inclusive, which connect the three groups of eight shelves each of the first-level working 'levels would I of ten oilices. Accordingly,

cating the drawings, no lines have been run-v to represent the other bundles of jumpers, but instead, the numbered circles have been provided to indicate corresponding points etween which the ten jumpers should be run. As an example, a bundle of ten jumpers should be run between two points indicated by the two circles numbered 113. j

It is assumed that the tratlic is comparatively lieavy on the fourth and fifth levels, which may be the case if the corresponding thousands groups handle a conslderable amount of private branch exchange traliic or contain a larger than usual proportion of business lines.. Accordingly, only six shelves can be multipled together on these two levels in order to furnish all the traic that can be safely carried by ten trunks. Each of the other* four working levels, 2, 3, 7 and 8, carries the average amount of traflic and, accordingly, seven shelves are multipled together on these levels. Since, there are twenty-fourv shelves associated with the distributing frame and, since twenty-four is not a multiple `of seven, the shelves do not come out even, and the rouping must be extended to the distri uting frame and associated switches shown in Fig. 9 by way of the series tie cable 272. Taking the second level, for example, three complete groups of seven shelves each are formed on the distributing frame shown in Fig. 8 and the three bottom shelves are left over. The three bottom shelves are strapped together with the bare wire jumpers in the usual manner, and the ten jumpers are run to the proper trunk cable as is indicated by the two circles numbered 104. Another set of ten jumpers is then run from one of the multiply connected' shelves in the partially formed group between the points indicated kby the circles numbered 105. Since, four shelves are required to complete the group, the first four shelves shown in Fig. 9 are strapped together on the second level, and

the jumpers indicated by the circles num' bered 154 are run from the second block associated with the series tie cable 27.2 to one of the bank cable terminal blocks of the four multiply connected shelves, thereb completing the group of seven shelves whic is locatedv partly in one bay and partly in another bay.- As can be seen, each of the other three levels 3, 7, and 8 are taken care of in a similar manner. When the bottom of the distributing frame shown in Fig. 9 is reached, it is found that the shelves come out uneven again and, accordingly, the partially completed group is carried over to the next bay, not shown, through the series tie cable which extends to the next bay. This is carried out until the group comes out even, or until the last bay is reached and, if

a partially filled roup is encountered on the last bay, it may e taken care of by interconnecting it with one or two of the preceding groups or by any other Well-known expedient, such as reducing the number of switches to which is' has, access and making the remaining contacts artificially busy.

It is vthe usual practice, when one or more levels of a selector are dead, to multiple the contacts together throughout several bays .or in some instances throughout all the bays of selectors inthe oliice, and to connect the group to an. operator 'by way of a few socalled dead level trunks. Accordingly, the ninth and tenth levels on the distributin frame shown in Figs. 8 and 9, are strapped together from the top to the bottom, and the two levels are multipled within each bay byfa set of jumpers which are shown on the bank cable terminal blocks of the shelves B and B2, respectively. It is assumed that the trunk cable with which one of the circles 132, Fig. 8, is associated, is the one containing the dead level trunks and, consequently, the bundle of jumpers which is run between the points indicated by the two circles 132, provides an outlet for any calls which may land accidentally on the ninth and tenth levels in this bay. These dead level trunks are multipled over to the remaining bays through the multiple tie cable which is connected to the top'set of terminal blocks through the bundle of jumpers indicated by the circles.133. The dead4 levels in the other bays are jumpered to the corresponding blocks of the multiple tie cable and are thereby connected with the dead level trunks. For example, the ninth and tenth levels of thebay shown in Fig. 9, are connected with the multiple tie cable by a bundle of jumpers indicated by the' circles 185.

Referring now particularly to Fig. 10, which as before stated, is a detailed diagram showing an alternate method for combining several shelves of switches so as to enable the outgoing trunks to handle the same numberr of calls with fewer lost calls or a larger number of calls with the same percentage of 10st calls, this is a specific cross-connecting diagram and is shown merely to illustrate the amount of flexibility that can be secured with the improved distributing frame and, therefore, a specific case must needs be assumed. Accordingly, it will be assumed that this diagram represents the fourth level of bank contacts connected to the distributing frame shown in Fig. 8. In this drawing, one short heavy line indicates a set of three contacts, one

lhorizontal row of short heavy lines in the lower section indicates one bank cable terminal block, and one horizontal row of short heavy lines in the up er section represents a section of trunk ca le terminal block to which ten trunks extending to a shelf of Switches in the next series 1s connected. p

It is well-known that selector switches of the home position type such as are assumed to be used in connection with the improved distributing frame, always seize the first trunk to which they have access if it is idle, and if it is busy, test the next one and so on, always taking the first idle trunk. That being the case, it is natural to expect that the first trunk will be in use more of the time than any one of the others and that the trunks in order from 2 to 10 will each handle fewer calls than the preceding one. This is what proves out in practice and is an` established fact. It is known also that if the trunks can be combined into groups of more than ten each, say twenty, the larger groups are more eiiicient and, accordingly, the average number of calls handled per trunk is greater.

Referring now again to Fig. 10, the trunks accessible from the level of contacts shown there are combined into two groups of twenty trunks each instead of four groups of ten trunks each as shown in Fig. 8, thereby permitting the two groups to handle the traffic with a better margin. The way in which the trunks are combined in the groups will now be explained. The first five contacts of the shelves on this level f are strapped together in six sets of four, and

the last five contacts are strapped together in two sets of twelve. This means that any four shelves, the first four for example, have five trunks which are first to fifth choice to these four shelves, and which are not accessible to any other switches, and that these four shelves together with two other groups of four shelves each have common access as sixth to tenth choice to the five trunks which are multipled to the first twelve shelves an'd which are used only when all the' trunks individual to a group of four shelves are in use.

This arrangement, so far, is the usual common and individual trunking scheme. However, with the type of distributing frame commonly used heretofore, it has been impractical to divide the traffic 'on the outgoing trunk cables so that the various shelves of switches in the succeeding series all carry practicall the same amount of traffic. For example, if one shelf of switchesin the succeedin train handles' the traiiic from live indivi ual trunks and five common trunksv while -another shelf of switches handles traffic from ten individual trunks, the traic on the second mentioned shelf of switches will be very much greater than the traffic on the first shelf, and it will, consequently, be very difficult to figure out the correct'way to multiple the various shelves together of the succeeding series of switches in order to load the cablesoutgoing therefrom propcontact sets of the firstfour shelves; thatl it carries the traiiic from the sixth, seventh, and ninth contact setsv of the rst twelver shelves; and that it carries the traiiic froml the third and fifth contact sets of the second four shelves. These tei trunks according to a careful calculation, upon which it is unnecessary to dwell here, carry approximately halfthe traffic on the group of twenty and, consequently, the trafric carried by the cable which is connected to the next trunk cable terminal block above will carry approximately the same traffic for the reason that it takes care of the ten remaining trunks of the group.

The remaining shelves in this bay are similarly strapped and jumpered on the level in question, so as to form a second group of twenty-trunks, the jumpers being omitted in order to avoid complicating the dra-wings.4 The places to which the jumpers are connected are indicated by the circles which are numbered in pairs from 201 to 220, inclusive.

In order to even up the traffic amongst the various trunks in each group of five `individual trunks, the first five trunks in each alternate shelf of switches, beginning with the B shelf, are reversed as may be seen upon 'referrin to the numerals applied to the contacts. or exam le, the first set of contacts on the distributin frame which is connected with the B she f is connectedW frame, that is, the sixth trunk is sixthI choice, the seventh trunk seventh choice to all the switches, etc. If desired, however, the sixth to the ninth trunks, inclusive, may be reversed in each alternate shelf in case the situation demands it.

The tenth trunk under normal conditions handles very little traffic, -being used only when five trunks in some individual oup are busy and when the four preceding com-l mon trunks are busy. Under the arrangeyment contemplated, the tenth trunk is last choice to all the switches, so that a meter may be associated with the tenth trunk and will indicate quite accurately whether or not the group of twenty trunks is properly loaded. For example, if'the meter associated with the tenth trunk shows a very small number of calls or none at all for a given time, theA indication is that the group of twenty trunks is loaded vtoo lightly. On the other hand, if the meter indicates that the tenth trunk handles a large number of calls in a given time, the group may be overloaded to such an extent that a great many calls are lost for the want of a suflicient number of trunks.

Regarding the multiple tie cable shown in Figs. 8 and 9, it may be said that this cable is used principally inmaking changes in the amount of traiiie supplied to the various trunk cables after an exchange is installed and is seldom used to any great extent initially. As shown, this cable takes.

care of the dead level multiples between the bays shown in Figs. 8 and 9, and the other bays in the same group, as is indicated by the bundles of jumpers which are assumed to be run between the circles numbered 133-and 185.

According to a foregoing assumption, the selector switches associated with the distributing frames indicated in Figs. 8 and 9 are thousands selectors in a multi-office system and, accordingly, certain ones of these selectors are reached by office selectors in the local olicc, while the others are reached by way of the oice selectors in the other oices of the system. It commonly occurs that the thousands selectors reached by way of oney oiice has a tralic distribution amongst the 4.various levels dierent than the traffic distribution of the thousands selectors of the other ofices. This diference may be ,known incorrectly or not at all before the installation is made and may become known quantitatively-only after a traiiic study is made with the system in actual operation. It also often happens that while a study reveals that one oice oiers` a traiiicon one level that is heavier than was anticipated, another oice whose selectors are located on another bay has a traic on the same level which is correspondingly.lighter than was anticipated. When this condition arises, it is merely necessary to adjust the traiic on the level in question between the selectors of these two otlices only. In case the switches ot t-he'se two offices are located on adjacent bays, the re-distribution of traic is ordinarily effected through the series tie cables or the tie cables such as the series tie cable 272, Figs. 8 and 9, which extend only between adjacent bays. If the switches in question, however, are located on bays which are not adjacent to each other, the redistribution is made throughthe multiple tie cable such as tie cable 271, Figs. 8 and 9,

which is multipled through all the bayst terminals mounted'in said strips and pro-l trudlng outward therefrom on the front and rear thereof, certain of said terminals beingr multipled together throughout a plurality of said strips by conductors which extend along the front of said frame, other terminals mounted on said frame, outgoing conductors secured to said other terminals, and jumpers connected between the rearof said multiply connected terminals to certain ones of said other terminals.

2. A distributing frame having substantially parallel terminal strips mounted thereon, terminals in said strips and extending outward from the front and rear thereot, certain ones of said terminals being strapped together in rows substantially at right angles to said strips by conductors secured to 'said terminals on the front of said strips, two points of access on each terminal at the rear of the strip in which it is fastened, incoming conductors connected to each of said termlnals at one of said points of access, and outgoing jumpers connected to certain of said terminals in each multiply connected row, each of said jumpers being connected to the other of said two points otl access.

3.A A bay of switches, a distributing frame therefor, the shelves of switches in said bay being connected in groups on said frame as regards one level of bank contacts, trunk cables terminating on said frame, and jumpers connecting said groups with said trunk cables.

4. A plurality of bays of switches, a distributing frame for each bay, and series and multiple tie cables extending between said bays to combine them intoa single unit.

5. A distributing frame having sets of contacts arranged 1n vertical and horizontal rows, agroup of normal position automatic selector switches asociated with each horizontal row, certain of said contact sets in one horizontal row being multipled with contact sets in one or more other horizontal rows, the banks of the switches in, each of Said groups being multipled together straight, and a cable connecting one switch bank in each group to its associated horizontal row of contact sets, certain conductors in certain of said cables transposed as regards their connection with the contact sets terminals of another class arranged in a group apart from the terminals of the first class, straight bare wires running vertically yes up the front of the frame, one wire for each vertical row of terminals, said Wires serving to multiple together the several hor-izontal rows of terminals of the irst class, and jumper wires on the rear of said frame connecting the terminals of one of said horizontal rows with the group of terminals of the second class.

8. A distributing frame comprising two Vertical supports spaced apart, a series of insulating strips extending horizontally between' said supports and secured thereto, a

plurality of pin terminals extending hori' zontally through each of said strips from front to rear, each pin including a front portion t'o which a multiple wire may be soldered and a rear portion notched in two places for the attachment of a bank wire and a jumper wire, a second series of insulating strips extending across said supports, each strip having two series of perforations, terminal blocks mounted on the front of the strips of said second series, and a row of vertical pin terminals extending through each block with their ends in alignment with the perforations in two of said series.

9. An automatic switchboard section comprising a rack of switches and a distributing frame, said rack having a plurality of shelves of switches, bank terminals on said frame arranged in roups, groups of trunk terminals on said rame, cables extending from said shelves of switches to said groups of bank terminals, trunk cables connected to said groups of trunk terminals, sets of conductors connecting the groups of bank terminals to form major groups of bank terminals, and jumpers connecting each major group of Abank terminals witha group of trunk terminals.

10. An automatic switchboard section comrising two parallel racks of switches and a 'stributing frame, each rack having a plurality of shelves of switches, groups of bank terminals on said frame, groups of trunk terminals on said frame, cables extending from the shelves of switches on one rack to one end of said frame and terminating on the odd numbered roups of bank terminals, other cables exten ing from the shelves of switches on the other rack to the other end of said frame and terminating on the even numbered groups of bank terminals, trunk cables connected to said groups of trunk terminals, sets of conductors connecting groups of bank terminals to form major groups of.

bank terminals, certain major groups each comprising both odd and even numbered groups, and jumpers connecting each major group of bank terminals with a group of trunk terminals.

l1. An automatic switchboard section comprising two parallel racks, each having a plurality of superimposed shelves of switches, a distributing frame spaced away from said racks at one end and extending at 'right angles thereto, the opposite ends of said frame being substantially in ali nment with said two racks, respectively, an a rectangular framework at the top holding said racks andframe in position.

' 12. In an automatic switchboard section, an upright panel shaped distributing frame, two parallel switch racks extending at right angles to said frame and spaced apart a distance approximately equal to the width of said frame, means connecting said racks and frame together at the top, switchl bank cable terminaison one portion of said frame, trunk cable terminals on another portion of said frame, and jumpers connecting certain of said bank cable terminals with certain of said trunk cable terminals.

13. In an automatic switchboard section, an upright panel shaped distributing frame, two parallel switch racks-extending at right angles to said frame and spaced apart a distance approximately equal to the width of said frame, means connecting said racks and frame together at the top, switch bank cable terminals on one portion of said frame, trunk cable terminals on another portion of said frame, jumpers connecting certain of said bank cable terminals with certain of said trunk cable terminals, and a vertical row of jumper rings on each rack for holdl ing the 'jumpers in orderly groups away from the back of said frame.

14. In an automatic switchboard section, a distributing frame, two arallel switch racks adjacent thereto exten ing at right angles to said frame and spaced apart a distance approximately equal to the width of said frame, switch bank cable terminals on one portion of said frame, bank cables extending from said racks to said terminals, trunk cable terminals on another portion of said frame, and jumpers connecting certain of said bank cable terminals with certain of said trunk cable terminals.

15.` In an automatic switchboard section, a

thereto extending at right angles to said frame, switch bank cableterminals on one ortion of said frame, bank cables extendlng from said rack to said terminals, trunk cable terminals on another portion of said frame, and jumpers connecting certain of said bank cable terminals with certain of said trunk cable terminals.

16. In-an automatic switchboard section, two switch racks spaced apart, a distributing frame adjoining said racks, switch bank cable terminals on one portion of the frame, bank cables extending from said racks to said terminals, trunk cable terminals on another portion of said frame, and jumpers connecting certain of said bank cable terminals with certain of said trunk cable terminals.

17. In an automatic lswitchboard section, a distributing frame, a switch rack, switch bank cable terminals on one portion of-said trame, bank cables extending from said rack to said terminals, trunk cable terminals on another portion of said frame, and jumpers connecting certainA of said bank cable terminals with certain of said trunk cable terminals.

18. In an automatic switchboard section, a distributing frame, two parallel switch racks extending at right angles to said frame and spaced apart a distance approximately equal to the width of said frame, switch bank cable terminals on one portion of said frame, trunk cable terminals'on another portion of said frame, jumpers connecting certain of said bank cable terminals with certain of said trunk cable terminals, and` jumper rings on each'rack for holding the jumpers in orderly groups away from said frame.

19. In an automatic switchboard section, a distributing frame, two parallel switch racks extending at ri ht angles to said frame, switch bank cab e terminals on one portion of said frame, cables extendin from said terminals to said racks, trunk cab e terminals on another portion of said frame, jumpers connecting certain ofsaid bank cable terminals with certain. of said trunk cable terminals,'and a row of jumper rings for holding the jumpers in Aorderly groups away from said frame.

20. In an automaticy switchboard section, a distributing frame', a switch rack extend ing at right angles to said frame, switch bank cable terminals on one portion of said frame, cables extending from said terminals to said rack, trunk cable terminals on another portion of said frame, jumpers connecting certain of said bank cable, terminals with certain of 'said trunk cable terminals, and jumper rings for holding the jumpers in orderly groups away `from said frame.

21. In an automatic switchboard section,v

a distributing frame, two switch racks, switch bank cable terminals on one portion connections between the frame and the racks. 23. A connecting frame comprising a plurality of parallel rows of spaced contacts each contact' extending from the front to the rear of the frame, the corresponding contacts of all of the rows being in alignment, a plurality of multi-conductor cables mounted on one side of the frame each adjacent one of said rows of contacts, thecorresponding conductors of each of the cables .being connected to corresponding contacts `1n the adjacent row and conductors on the frame connecting correother side of the sponding contacts of certain of the rows.A

24. A connecting frame comprising a plurality of groups of spaced parallel rows of switchboard section osite ends A of which are adjacent both of sai racks, and

contacts, the contacts of each row being stagu gered with respect to the contacts in other rows of the same group-and in alignment withthe contacts of corresponding rows of other groups, a plurality of multi-conductor cables mounted on one side of the frame each adjacent one of the groups of contacts, the corresponding conductors of each of the cables being connected to corresponding contacts in the adjacent group, and conductors connecting corresponding contacts of bertain of the groups. j

2.5. In a telephone system, a plurality of rows of automatic switches, each switch containing a plurality of rows of contacts, a plurality of trunks, means for connecting corresponding contacts of different rows of switches in multiple to desired trunks, said means comprising a distributing frame having aligned rows of contacts extending fromj the front to the rear thereof, said trunks fbeing grouped in cables on one side of the frame, conductors grouped in 'cables on the same side of the frame connecting the last mentioned contacts with the switch contacts, conductors on the other side of the frame connecting aligned contacts of certain adjacent rows, and jumpers connecting each of said last mentioned conductors with a trunk.

In witness whereof, I hereunto subscribe my name this. 15th dayof December, A. D` 1922.

I HARLEY B. MOELYEA.

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