US3197550A - Variable count terminal and system - Google Patents

Description

July 27, 1965 D. J. SMITH 3,197,550

VARIABLE COUNT TERMINAL AND SYSTEM Filed Aug. 28, 1961 2 Sheets-Sheet l July 27, 1965 D. J. SMITH 3,197,550

VARIABLE COUNT TERMINAL AND SYSTEM Filed Aug. 28. 1961 2 Sheets-Sheet 2 FREE 4 FREE w mm - 172/612207': @oiza Zcl J 5 721 227:

United States Patent 3,1@7,5 VARHAELE CGUNT TERMHNAEZ AND SYSTEM Donald J. Smith, Eleepy Hollow ll lanor, lllh, assignor to Reliable Electric Company, Franklin Park, ill, a corporation oi lllinois Filed Aug. 28, 1961, Ser. No. 134,339 3 Qlaims. Cl. FEM-72) This invention relates to a variable count terminal for use in connection with a telephone cable or the like, and a system including same.

The usual terminal for overhead telephone cable comprises a splice casing which made in two halves, and a terminal box which is integrally formed with one of the splice case halves. The terminal box contains a terminal block having a number of binding posts, each pair of binding posts being permanently connected to one of the conductor pairs of the cable. The pairs of binding posts are generally much less in number than the number of conductor pairs in the cable, but on the other hand it is customary to provide at least twice as many binding post pairs as are required at the time of installation. The selection of the particular combination of conductor pairs which are to be tapped into is referred to as the complement, or count, and the complements of adjacent terminals are overlapped as explained below.

In order to provide for expansion of service, several free or unused lines are brought out in each terminal box. However, since the exact location of a future demand is unknown, the tree lines are also connected to binding posts in other terminal boxes, such as adjacent terminal boxes, As a matter of general practice, each line or conductor pair, Whether intended for immediate use or for future use, is connected to binding posts in two or more terminal boxes. Thus the selection of the particular complement or count is a matter which is given a good deal of thought in order to provide the greatest possible flexibility at the lowest possible cost.

In other words, to take a given example, in a residential neighborhood where one terminal is provided for each four stations or houses, a given terminal box will have eleven pairs of binding posts, of which only four are used at the time of installation.

The necessity for the remaining seven binding post pairs is dictated by the overlapping complement practice, even though the possibility of future expansion woulc call for only one or two additional binding post pairs at the most.

However, there are two practical difficulties encountered, one of which is that as many as three times the number of binding post pairs in actual use must be provided at each terminal box in order to attain the desired latitude in selection, and the other difiiculty is that the latitude of selection is limited by the originally selected complement. In other words, a binding post pair must be provided for each member of the complement; the larger the complement, the more costly the installation, but if each complement is made smaller to reduce cost, then subsequent latitude of selection is radically cut down. Therefore, the present practice requires a choice to be made between expense and latitude of selection.

According to the present invention, a method and means is provided which increases latitude of selection While at the same time cost is held to a minimum. This is accomplished by providing a ratio of complement pairs to binding post pairs which is much greater than 1 to 1, by providing for each terminal a complement which is much greater than the complement heretofore used, and by providing a number of binding post pairs which is much less than that heretofore used.

Another object of my invention is to provide a terminal Eddifilid which can be used in connection with pressurized cable.

A further object is to provide a terminal arrangement which reduces electrical leakage over the prior art arrangements.

Other objects, features and advantages will become apparent as the description proceeds.

The invention is illustrated herein with respect to both the stub-end type of terminal box and the in-and-out type.

With reference now to the drawings in which like reference numerals designate like parts:

FIG. 1 is an elevation showing a preferred embodiment of my invention, as applied to a stub-end type of terminal box, the cover of the terminal box being shown in its open position;

FIG. 2 is a vertical section taken along line 2-2 of FIG. 1,

FIG. 3 is a diagram illustrating the nature of the invention, and

FlG. 4 is a view similar to FIG. 1, showing my invention as applied to an in-and-out type of terminal box, the cover being omitted.

In FIGS. 1 and 2, the reference numeral 10 indicates a terminal Which is used in connection with two splice case halves ill and 12. The latter are provided with abutting flanges l3 and a gasket 14, and flange clamping means 15 urge the two halves ll and 12 into engagement with each other to provide a sealed splice case. The end portions 16 of the splice case are sealed to the sheath of a cable 117, by means of suitable sealing compound or by means of a wrapper of gasket material so that the splice case as a whole provides a hermetically sealed structure with respect to the cable 17.

Such a splice case is commonly used either where two lengths of telephone or other communication cable are to be spliced to each other, or else where it is desired to remove the cable sheath in order to splice the various conductor pairs of cable stub at a terminal point. As an example of the sealed nature of the splice case, it can be pointed out that they are frequently used in connection with pressurized cables. The cable 17, for example, may contain as many as one hundred conductor pairs or more, and the conductors of each pair may be either paper insulated or plastic insulated.

The terminal ll) comprises a terminal box 18 having a hinged cover 19. The terminal box 18 is mounted on the splice case half 11 which is provided with two bosses 20. Suitable screw threaded fasteners 21 and 22 mount the rear wall of the terminal box 18 to the bosses 29, but the screw threaded fastener 22 is in the form of a hollow bushing through which cable stub 23 passes. The bushing is provided with suitable gasket means to provide a gas-tight seal for the cable stub.

The cable stub 23 comprises a bundle of polyethylene insulated wires which are preferably grouped in pairs, as by twisting, and which are color coded. As an example, the cable stub may comprise twenty-six conductor pairs. The cable stub 23 is a stub-end cable stub, and it includes a stub-end 25 which is in the form of a plastic cup in which the free ends of the conductor pairs 24 are received and embedded in a suitable potting compound. The terminal box 1% includes a clip 26 for supporting the stub-end 25.

The terminal box may also be provided with one or more hangers 27, in the form of wire hooks, which support the cable stub 23 at one or more intermediate points and in such a manner that a slack loop 2%, is provided.

The opposite end of the cable stub 23 is the splice end 29 which extends through the bushing 22 and into the splice case 11-12. The cable stub 23 is cut to a length such that various conductor pairs 24 can be spliced into v.9 the cable 17 and so that slack loop 28 will still be provided.

Mounted in the terminal box 18 is a terminal block 3t) which is secured to the rear walls by suitable screws 31. The terminal block serves as a mounting means for a plurality of binding post pairs 32.

Tu maldng a splice, a section of the lead sheath of the cable 17 is first removed, and then the various conductor pairs of the splice end of the cable stub 23 are connected to the selected complement of the conductor pairs of the cable. Then the splice case llll2 is applied to the cable and scaled up. At this stage of the operation the terminal appears as is shown in FIG. 1, when the cover 19 has been opened.

When it is desired to connect a service drop wire to a particular conductor pair of the complement, that conductor pair is first separated from the cable stub 23 and then pulled downwardly, as indicated by the dotted line loops 33 in FIG. 1 to make connection with a binding post pair 332. ln making this connection, the polyethylene insulation is scraped from the ends of the loops 33. It will therefore be seen that the slack loop 28 provides sufiicient slack so that the individual loops 33 may be formed. Then the service drops can be brought into the case through suitable grommets 34 formed in the bottom wall. The element 35 in FIG. 2 consists of one or more wire hangers to support the drop wires.

The foregoing arrangement, in which cable stub 23 runs for the full length of the terminal box 1%, provides sufficient length to permit manipulation of the cable stub in connection with the separation of and looping down of the desired member of the complement.

Assuming that there are twenty-six conductor pairs in the cable stub 23, and only six binding post pairs, it therefore follows that there will be twenty or more unused conductor pairs in the complement. The insulation of these unused pairs is not broken at any point, the free end of the pair being embedded in the stub end 25. Therefore, there is a greatly reduced number of appearances, or electrically exposed conductor pairs in this arrangement than in the case of the prior art, in which there would be a one to one correspondence between the number of conductor pairs in the complement and the number of binding post pairs. As a result of the reduced number of appearances, there is much less electrical leakage on the line.

The slack loop arrangement also has the advantage of permitting direct termination of a conductor pair without the cutting of any wires.

Since the splice case is sealed, my invention can be used with pressurized cable.

Assuming that four binding post pairs have been connccted to service drops, and it is desired to add another service drop, it will be seen that any one of the twentytwo unused members of the complement can be selected and connected into without the necessity of opening up the splice case. Similarly the service drop can be connected to a different member of the complement Without opening up the splice case, although it will be understood that the previously used loops 33 must be retaped when disconnected from the given binding post pair.

Thus, in the example shown, the latitude of selection provided is equivalent to that provided by a twenty-six pair terminal. This would require a much larger terminal box than that shown in FIG. 1. The usual terminal box is furnished to the trade in capacities of six pairs, eleven pairs, and sixteen pairs. The terminal box 18, shown herein, is the eleven pair size. Therefore, it will be seen that a six-pair terminal block installed in an eleven-pair size terminal box provides much greater latitude of selection at somewhat lesser cost, due to the six-pair terminal, than does the ordinary eleven-pair terminal of the prior art.

In the case of underground communication cable, the splice case or its equivalent will be located underground, and the terminal box 1? will be located on a post above the ground. Here the cable stub 23 will include a section of lead sheath cable extending between the bushing 22, and the splice case. In the event that the underground cable is pressurized, the cable stub 23 will have a pressure plug which is located within the terminal box 18.

A simplified diagram illustrating the invention is shown in MG. 3. The cable 17 is represented as a ten-conductor pair cable, each conductor pair being designated by the reference letters a to j. Three terminals A, B, and C are shown, each having three pairs of binding posts, 1 to 3, 4 to d and '7 to 9, of which two binding post pairs are in use, and a third binding post pair, 3, 6 and 9, respectively is reserved for future demand.

The cable stubs associated With each terminal are shown as 23, 23 and 23". The complements a to e, b to f, and d to h overlap so that the four conductor pairs b, c, d, e are common to terminals A and B, and so that the three conductor pairs d, e and f are common with respect to terminals B and C, and there are two conductor pairs d and e which are common to all three terminals.

According to the examples shown the conductor pairs of and e are free conductor pairs, in the sense that they are not connected to any pair of binding posts. Therefore, if future demand calls for another pair of terminal B, the binding post 6 can be connected to either one of the two conductor pairs (1, or e, and similarly with respect to terminals A and C.

In other words, it can be assumed that the demand at any one terminal will not be in excess of one binding post, and it can be further assumed that the total demand for the three terminals will not be more than one or two conductor pairs. However, according to prior practice, it would have been necessary to provide five binding post pairs at each terminal in order to satisfy this set of conditions, whereas according to the given example, three binding post pairs are sufficient, and provide the same latitude of selection as the prior art arrangement, but at a lesser cost.

Overlapping of used conductor pairs is also Provided in the event the party line connections are desired, as illustrated by conductor pair b which is connected to binding posts 2 and 4 in different terminals.

As previously indicated, there are two types of cable stubs, the stub-end type and the in-and-out type, and terminal boxes are usually supplied with either type.

FIG. 4 illustrates the invention as applied to the in-andout type of terminal box 1%. The same reference numerals primed are used to identify the identical parts.

lowever, instead of having only one bushing type fastener, both of the fasteners 22 and 4d are in the form of hollow bushings. The cable stub dll is an in-and-out cable stub, both ends of which extend through the bushings 22' and 4d, and both ends of which constitute splice ends.

In splicing a cable, after the sheathing has been removed and the particular conductor pair has been located, it is necessary to sever the conductor pair so that the two ends may be brought out of the cable. In the stub-end type of splicing, a piecing-out length of wire is used to connect the two severed ends of each conductor of the pair, and one of these connections forms the point where the corresponding conductor of the stub-end type of cable stub is connected. However, in the in-and-out type of splicing, the cable stub itself serves as the piecing-out length of Wire with the result that the in-and-out cable stub in itself forms a part of the circuit.

In FIG. 4, there is no stub end 25 and no clip 26 for supporting same; rather the cable stub il is supported at both ends by the bushings 22' and and at intermediate points by the hangers 27. An additional slack loop 42 may be provided, if desired, so that the span of the inandout cable stub 41 will extend for substantially the full length of the terminal box 18'. The manner in which the conductor pairs 24 are extended to make a connection with the binding post pairs 32 is the same as de scribed in connection with FTGS. l and 2.

Although only a preferred embodiment of my invention has been shown and described herein, it will be understood that various modifications and changes may be made Without departing from the spirit of my invention as pointed out in the appended claims.

I claim:

1. In combination, a cable having a plurality of conductor pairs, a plurality of terminals, each terminal including a cable stub having a plurality of conductor pairs which is less in number than the conductor pairs of said cable, and a plurality of binding post pairs which is less in number than the conductor pairs of said cable stub, each cable stub being connected to said cable so that the complement of each cable stub is different from the complement of all other cable stubs, and each complement including members which are common to other complements, said complements being overlapping complements, certain ones of said binding post pairs of each terminal being connected to certain members of its associated complement, each terminal including at least one binding post pair which is unconnected, and each complement including a plurality of free common members which are not connected to a binding post pair in any terminals Whereby the ability is provided, in the event of expansion of service, to connect one of said unconnected binding post pairs to any one of a plurality of said free common members of an associated complement.

2. The combination as claimed in claim 1 in which the number of said free common members of each complement is less than the total number of said unconnected binding post pairs included in all the terminals of said combination.

3. The combination as claimed in claim 1 in which said cable stubs are stub-end cable stubs, and in which said conductor pairs are jacketed conductors, said cable stubs including means for insulating the free ends of said jacketed conductors to reduce electrical leakage of the system.

References Cited by the Examiner UNITED STATES PATENTS 831,876 9/06 Keith 179-98 857,341 6/07 Grace et al 174-60 1,917,242 7/33 Emmons 174-41 2,021,594 11/35 Emmons 174-59 2,078,991 5/37 Baker 174-60 2,264,803 12/41 Jacobs 174-76 X 2,683,304 7/54 Channel 174-41 X 2,891,101 6/59 Koliss 174-92 X 2,953,625 9/60 Hasselhorn 74-71 X 2,957,038 10/60 Greenidge et a1. 174-23 FOREIGN PATENTS 429,678 9/11 France.

JOHN F. BURNS, Primary Examiner. JOHN P. WILDMAN, Examiner.

Claims (1)

1. IN COMBINATION, A CABLE HAVING A PLURALITY OF CONDUCTOR PAIRS, A PLURALTITY OF TERMINALS, EACH TERMINAL INCLUDING A CABLE STUB HAVING A PLURALITY OF CONDUCTOR PAIRS WHICH IS LESS IN NUMBER THAN THE CONDUCTOR PAIRS OF SAID CABLE, AND A PLURALTIY OF BINDING POST PAIRS WHICH IS LESS IN NUMBER THAN THE CONDUCTOR PAIRS OF SAID CABLE STUB, EACH CABLE STUB BEING CONNECTED TO SAID CABLE SO THAT THE COMPLEMENT OF EACH CABLE STUBS IS DIFFERENT FROM THE COMPLEMENT OF ALL OTHER CABLE STUBSM AND EACH COMPLEMENT INCLUDING MEMBERS WHICH ARE COMMON TO OTHER COMPLEMENTS, SAID COMPLEMENTS BEING OVERLAPPING COMPLEMENTS, CERTAIN ONES OF SAID BINDING POST PAIRS OF EACH TERMINAL BEING CONNECTED TO CERTAIN MEMBERS OF ITS ASSOCIATED COM-

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