US3048003A - Method of forming dead ends for cables - Google Patents

Description

1962 R. L. PAYER 3,048,003

METHOD OF FORMING DEAD ENDS FOR CABLES Filed April 15, 1959 5 Sheets-Sheet 1 3 E24 8L #79 Z Aug. 7, 1962 R. L. PAYER METHOD OF FORMING DEAD ENDS FOR CABLES 3 Sheets-Sheet 2 Filed April 15, 1959 Rodolph L p v Afflihn a 7 Aug. 7, 1962 R. L. PAYER 3,048,003

METHOD OF FORMING DEAD ENDS FOR. GABLES Filed April 15, 1959 '6 Sheets-Sheet 3 DEAD g v END /2 Ihre 1 A Rodolfl f pvek @1 30... ,7 ,44 yh ll I fimhgy fitice United States 3,048,003 METHOD OF FORMING DEAD ENDS FOR CABLES Rodolphe Leo Payer, RR. 1, Waterdown, Ontario, Canada Filed Apr. 15, 1959, Ser. No. 806,585 Claims priority, application Canada May 21, 1958 2 Claims. (Cl. 57-160) This invention relates to an improved closed attach. ment loop for elongated linear bodies such as cables and is particularly concerned with an improved method of forming a dead-end in stranded cables of the type used in electrical distribution systems.

Those private companies and public utilities concerned with the distribution of electrical energy by means of been spent in seeking ways to improve electrical distribution systems and in recent years a substantialstep forward has been taken by the invention and introduction to the industry of pre-fabricated products which are simple to use and hence require correspondingly less skill of the operator and are, by virtue of their simplicity, time-saving in installation and also frequently reduce the cost of material required.

One such product whose success is attested by the widespread adoption it has received throughout the electrical distribution industry is the preformed, resilient, helicalrod of the type described by Thomas F. Peterson in his US. Patent 2,587,521 and later improvement U.S. Patent 2,609,653. These helically preformed rods are currently employed in a variety of ways including cable reinforcement, splicing, and the lashing of cables to messenger strands; one such application in which these helical units have proved of particular merit is concerned with the formation of dead-ends or closed attachment loops at the ends of transmission lines or guy Wires and this subject is discussed by Peterson in his US. Patent 2,761,273.

r I The present invention is similarly concerned with the formation of a dead-end in a transmission line orguy wire utilizing resilient, helically-preformed rods and discloses an improved dead-end of this type and a method of making the same, which overcomes several notable de- Patented Aug. 7, 1962 length of the transmission line or guy wire while the dead-end is being formed so that there is a minimum of slack to be taken up when the tensional load is applied to the dead-end, thus permitting a highly accurate control of the final load which is transmited to the dead-end from the transmission line or guy wire. This improved dead-end has the additional virtue that no particular skill other than that normally expected is needed by the linesman to arrive at this correct loading figure.

According to the present invention a closed attachment loop in an elongated linear body, such as for example a dead-end at the end of a transmission line or guy wire, is formed by first preforming a number of helical elements to such an internal diameter that when these elements are wrapped coaxially about this body they will grip it tightly; the elements are then each wrapped about the elongated body for a portion of their length after which the body is formed into a loop and another portion of each of the elements is wrapped around the body beyond this loop.

When formed in this manner the closed attachment loop thus comprises a bight in the body with the two arms of the bight being generally parallel to one another, and a closure for the loop for-med by resilient preformed helical elements fixing these arms in position relative to i one another, the helical elements each having a portion of their length wrapped in tightly gripping engagement coaxially about one arm of the bight and -another portionof their length wrapped in similar engagement about the other arm of the bight.

In the natural programme of events, it is inevitable that, after the transmission lines have been installed and in use for a period of time the system will relax to some extent and this means that maintenance crews must go around and rework the dead-ends to take up the slack which has appeared in the lines. 7

. Though the earlier methods of forming dead-ends using preformed helical rods in themselves represented a considerable advance over the earlier methods, which utilized:

clamps, a dead-end formed according to the present invention is more quickly and more easily reworked to take up anyslack which has appeared even than these earlier methods and accordingly it is a further object of this invention to disclose a dead-end which can be readily and speedily reworked by maintenance crews as a and when necessary to take up any slack which has apficiencies. of previous dead-ends including those shown in the above mentioned Peterson patent;

One major drawback of the previously known deadends'formed by the use of preformed helical rods has been that such dead-ends were formed in an unloaded condition, that is, the tension load which the dead-end had to bear in use was not transmitted to the dead-end orto that part of the cable to which the helical rods were attached until such times as the installation was completed. This meant that the dead-end and the untensioned portion of the cable always stretched a little when the tension load was applied to themwith a corresponding reduction in the tension previously present in the cable.

I 1 It is accordingly an object of this invention to provide a dead-end and a method of making the same in which the tensional load is applied throughout the entire useful peared throughout the transmission system.

Other objects and capabilities of the present invention will become evident from an examinationoi the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 and FIGURE la show. side and end elevations respectively of a preformed helical rod typical of those used in the present invention. 7 7

FIGURE 2 shows such a rod applied'to a strand of cable; with FIGURE 2a showing a cross-section. of the cable and FIGURE Zbshowing the cross section of the cable with the helical rod wrapped around it.

FIGURE 3 illustrates the manner in which a dead-end was typically formed according to a previously known method employing preformed helical rods.

FIGURE 4 illustrates a typical dead-end using helical preformed rods and the manner in which it is formed according to the present invention. r

, FIGURE 5 illustrates the half-lay configuration of preformed helical rods utilized as a preferred embodiment in the present invention. 7

FIGURE 6a is a side elevational view of a transmission line assembly showing the dead-end arrangement of the present invention in operative association therewith, and

FIGURE 6b is a side elevational view of a guy wire assembly, showing the dead-end arrangement of the present invention in operative association therewith.

As stated previously, one of the major factors contributing to the simplicity and facility of use of the present invention is the preformed helical rod of the type disclosed by Peterson in his US. Patent 2,587,251 and such a rod is shown in FIGURES l and 1a.

The rod is formed into a uniform spiral and its chief physical characteristics are its pitch length I, that is, the longitudinal distance occupied by one complete revolution of the helix; its internal diameter d, that is the internal diameter of the hollow body formed when the rod is viewed in end elevation; and the nature and composition of the material used in its construction.

Concerning the nature of the material used to form the rod, it is obvious that one basic requirement is that the rod be resilient, so that it is capable of being wrapped around a cable from the side without exceeding the elastic limit of the materials used in its construction, as otherwise its gripping qualities would be seriously aifected. Within this broad limitation it is possible to use a wide variety of materials and these are selected on the basis of the use to which the rod is to be put and also the type of cable around which it is to be wrapped, as care must be taken to ensure that electrolytic deterioration does not take place between the metal of the rod and the metal of the cable. Typical materials used are aluminum, galvanized steel, bronze, stainless steel, copper and copper weld. It is also possible to use materials having electrical insulating properties, such as synthetic or treated wood.

When such a rod is wrapped around a cable, a prime requirement is that the rod be wrapped coaxially about this cable in tightly gripping engagement with it and, in the case of the stranded cable, that the rod engage as many of the strands of the cable as possible throughout its length.

As will be apparent, from FIGURES 2, 2a and 2b, the preformed helical rod 1 when wrapped around the cable 2, in order to grip this cable tightly must have its internal diameter d less than the external diameter D of the body formed by the outer. strands 3 of the cable 2. When this is done and the rod is formed of a resilient material in the manner described above, then a tight grip will be exerted by the rod on the cable and it will resist very strongly efforts to move it in a longitudinal direction.

This tight grip is present even though the elongated body around which it is wrapped is not necessarily a cable or even a stranded cable. However, since these rods find particular, though not unique, employment in association With stranded cables, they have been designed to have certain physical properties which are dependent upon the construction of the cable with which they. are associated.

The first of these concerns the manner in which the helix is wound, relative to its longitudinal axis. Such winding can obviously be either clockwise or anti-clockwise about this axis, and the direct-ion of lay, as it is called, of the rod is termed right hand and left hand respectively for these two conditions.

If the lay of the rod was in the opposite sense to the lay of the strands of the cable then the rod would run over the top of the strands of the cable and only a very small surface area of the rod would-be in contact with the strands of the cable. For this reason, it is usual to have the direction of lay of the preformed helical rod correspond to the direction of lay of the strands of the cable.

A second physical characteristic common to the rod and the cable is their pitch length. At first glance, it would seem. that the ideal conditions of frictional engagement would arise when the pitch length l of the rod 1 was identical to the pitch length L of a strand of the cable. However, it has been found in practice, that it is advisable to have the pitch length of the rod less than the pitch length of the strands of the cable and this is 4 fully explained by Peterson in his aforementioned U.S. Patent 2,609,653.

A number of rods can be grouped to lie about the cable and may be in touching contact or may be spaced apart along the cable, and their number can obviously vary to suit the particular requirements of the conditions under which the rod or rods has to be used, subject always to the over-riding proviso that the rods, acting in conjunction, obtain sufficient purchase about the cable to resist any force tending to make them slip along it longitudinally. In FIGURE 5 is shown a particularly useful grouping of rods 17 known as a half-lay because of the fact that the aggregate axial length occupied by the rods is approximately half the total pitch length l of the individual rods, or in other words one half the number of rods are present in this configuration than would be required to completely enclose the cable with preformed helical rods.

it is this property which makes the half-lay particularly attractive since two such half-lays will completely enclose the cable when armouring a cable or splicing a break, and so the half-lay has become available as a standard item of manufacture and thus forms a convenient unit for use in the present invention.

In order to more fully demonstrate the manner in which the present invention distinguishes over the dead ends and method of forming them by the use of preformed helical rods disclosed and claimed by Peterson in his earlier patent some space will be devoted in this specification to the method most commonly used to form a dead-end according to Peterson which uses the preferred half-lay configuration of preformed helical rods and this method is illustrated in FIGURE 3, which has been labelled Prior Art so as to avoid confusion with the method of the present invention.

The standard cable 2 is a guy wire descending from a distribution pole, which must be connected under tension to the ground anchor 21. To do this, an ancillary anchor device 5 is slipped around the shank of the ground anchor. A clamping member 4 of the commonly used tensioning device known as a come-a-long is applied to the cable at a suitable distance from the ground anchor and a length of cable 8 is then used to interconnect this clamping member 4 and the ancillary ground anchor 5. One end of this chain 8 is fitted with a hook 7 which engages an anchoring eye on the anchoring device 5 and the other end of the chain passes through a ratchet device 9 to which is attached a second hook 6 which is passed through an eye of the clamping member 4. Now as the ratchet handle is rotated in the manner shown, a tensional load is applied to the cable 2, and the chain 8 and the cable 2 become taut under this 1oad..

Below the clamping member 4 there is a tail section 13 of the cable which is not under tension and which will therefore stretch slightly when a tensioning load is applied to it. It is at the end of this tail portion 13 that the dead-end must be formed and, though Peterson discloses a variety of ways of doing this, in his most common embodiment, this dead-end is formed by passing a halflay 10 of preformed helical rods through the eye 14 of the ground anchor 21. A bight is formed in this half-lay and the two arms of the half-lay 11 and 12 extending from this bight are made substantially equal. These two arms and the tail piece 13 are then brought together running generally parallel to one another and the two arms 11 and 12 are wrapped about the tail 13 so forming the dead-end at the end of the cable or guy wire 2, in the manner described by Peterson in his US. Patent 2,761,273.

The tensioningdevice is then slacked off and the tensional load in the cable 2 is transferred to the dead-end 10. In doing so, it takes, up an appreciable amount of slack in the tail portion 13 of the cable and the bight;

portion of the half-lay 10. It is very difiicult to accurately predict the amount of slack which willhave to be taken up and so not inconsiderable skill is required on the part of the operator to estimate whether the final tensional load on the guy wire will be of the correct value. It should also be noted that an appreciable portion of the half-lay is used to form the bight for the dead-end, thus reducing the length of the half-lay which is in tighlty gripping engagement with the tail portion 13 and also of course efiectively adding to the cost of material used since, though used purely as a bight and thus not utilizing its peculiar helical properties, this section nevertheless forms part of the'preformed half-lay of helical rods and must be purchased as such.

There thus emerge three major drawbacks to this method of forming a dead-end. Firstly, that it is very difli cult to accurately predict the final tensioning load in the guy wire; secondly, that an ancillary device in the shape of the special anchor mechanism 5 must be provided and thirdly, that a portion of the half-lay used in the formation of the dead-end is efiectively Wasted, thus either reducing the gripping surface allowable for any given length of half-lay or conversely effectively wasting material if the gripping surface is considered to be constant.

Consider now the dead-end formed as a preferred embodiment of the present invention in the manner shown in FIGURE 4. As for the Peterson method, the clamp ing member of the tensioning device or come-a-long is applied to the guy wire stranded cable 2 an appreciable distance above the ground anchor 21 and one book 6 of the come-a-long is fixed to this clamp. But then, for the present invention, the guy wire .is then passed through the receiving eye of the ground anchor 21 to form a bight 14 and is then led back upon itself in a substantially parallel relationship for some distance and a second clamping member 4a is then applied to the cable. To this second clamping member 4a is applied the other hook 7 at the end of the chain 8 of the come-a-long. Now when the ratchet mechanism 9 is rotated and the cable 8 is tightened it will be seen that the tension-a1 load is applied throughout the entire guy wire; there is still a tail portion 13 which is not under tension but this tall portion is not used in the present invention and so the loss in tension due to the stretching of untensioned cable when the load'is applied is obviated.

. Having thus positioned the guy wire cable in the form of a loop comprising a bight 14 and the two substantially parallel arms 16 and 17, the whole system being under thedesired tensional load, it becomes necessary to close the top of this loop and thus render it useful as a deadend and this must be done in such a manner that When the tensional load is applied to the loop by the relaxation of the tensioning device the dead-end will stay firm and resist the tensional load. This is done by wrapping a portion of the length of each of a plurality of preformed helical rods, which as stated are to be most generally found in the half-lay configuration, about one of the! arms of the bight. Though the only requirement of this gripping portion is that it provides sufficient purchase to resist the tensional load it will be obvious that, in practice, substantially half. of the half-lay 17 will be Wrapped around this arm of the bight 14. After this first portion has been wrapped the remaining portion is then crossed over to the other arm of the bight and wrapped around it, starting ofi at the termination of the first portion and continuing in the same direction as this first portion. It will be noted that except for the very small connecting portion 18 substantially all of the half-lay is wrapped in tightly gripping engagement about the guy wire and that no portion of the preformed rods is wasted in the formation of the actual bight so that the whole length of the lay is effective to grip the cable.

Now-when the tensional device is slacked ofi, and the tensioning load is transferred to the dead-end, there is only an extremely slight, if any, extension of the various members as the load is applied to them andso the final tensional load in the structure can be quite accurately predicted. As stated above, no part of the half-lay is wasted in forming the bight and thus the fullest possible purchasing power is realized from the helical rods and moreover no special equipment in the shape of an ancillary anchor is required, though admittedly an extra clamping member 4a is required, butit must be remembered such equipment is standard issue to linesmen and would not necessitate a special purchase on the part of the appropriate authority.

The three major drawbacks of the earlier method have thus been overcome and there is the further benefit that this dead-end is extremely easy to make and may be reworked if, and when required in the natural process of time by maintenance crews without any special equipment or any peculiar skill other than those normally associated with persons practising this art. g

It should be noted that of the full tension load above the dead-end, only half is effectively borne by the helical rods forming the half-lay. Though. Peterson in his earlier US. Patent 2,761,273 does disclose dead-end formations in which only half of the load is borne by the helical rods, in his preferred embodiment, as shown in FIGURE 3, the full tension load is borne by the rods which must also pass through the receiving eye of the ground anchor and thus bear this full tensional load at the point where they are undergoing maximum deformation. Thus as a matter of common field practice, the safety factor of the present invention is higher than that of the earlier Peterson methods.

It will be obvious that the direction in which the halflay is wrapped around the respective arms of the bight is critical for though the dead-end will be able to resist some tensional load no matter which way the half-lay is wrapped around the two arms of the bight provided that a portion is wrapped around each arm, nevertheless the optimum conditions will only be achieved when these two wrapped portions are wound so that they resist the tensional pull along the cable. It is obvious that to accomplish this, if the first half portion is wrapped around the main arm 15 of the cable forming the bight, then this first portion should extend in the direction of the bight and that upon a trans- \fer to the second arm of the bight 15 in the lead back part.

of the cable, that the second portion should also extend in the direction of the bight, or in other words, a portion of the half-lay should be wrapped around the cable before the bight and a portion should be wrapped around beyond the bight, the second portion commencing adjacent upon the termination of the first portion and extending in the direction of the bight.

The dead-end disclosed in the present specification has only been described in conjunction with its uses as the termination of a transmission line or a guy wire in the manner shown in FIGURES 6a and 6b where, in the case of FIGURE 6a, the transmission line 2 terminates in a dead-end at the pole 2.0.and, in the case of FIGURE 6b,

the guy wire 19 has a dead-end at either end to brace the pole 20 to enable it to resist the pull of the transmission cable, but it is nevertheless not intended that the present invention should be restricted in its scope or spirit purely to these preferred embodiments but rather may be utilized as appropriate within the scope and breadth of the appended claims.

I claim:

1. The method of dead-ending a stranded cable and the like which comprises forming a half-lay of helicallypreformed elements, said elements having a common pitch length less than, and a direction of lay corresponding to, the strands of said cable, and being of an internal diameter less than the external diameter of said cable; passing said cable through a receiving eye; leading said cable back upon itself to form a dead-end; placing and maintaining said cable in tension by suitable releasable tensioning means; wrapping approximately a half portion of said half-lay coaxially about the lead back section of the cable forming said dead-end in a direction away from said dead-end; wrapping substantially the remaining portion of said halflay coaxially about the other section of the cable torn ing said dead-end in the same direction as said half portion; and releasing said tensioning means whereby to transfer the tensional load on said cable to said half-lay.

2. The method of dead-ending a stranded cable and the like which comprises forming a half lay of resilient helically preformed elements, said elements having a common pitch length less than or equal to the strands of said cable, and a direction of lay corresponding to said strands, said elements being of a common internal diameter less than the external diameter of said cable; said method including the steps of wrapping substantially half a portion of said half-lay coaxially about said cable whereby to attach said half portion in tightly gripping engagement with part of said cable; forming a bight in said cable beyond said engaged part; leading back at least part of the cable be- I yond said bight to lie in substantially parallel relationship References Cited in the file of this patent UNITED STATES PATENTS 662,171 Lederer Nov. 20, 1900 788,136 Heilrath Apr; 25, 1905 1,125,374 Neuman et al Jan. 19, 1915 2,230,611 Cofiin et a1 Feb. 4, 1941 2,587,521 Peterson Feb. 26, 1952 2,736,398 Peterson Feb. 28, 1956 2,761,273 Peterson Sept. 4, 1956 2,959,632 Peterson Nov. 8, 1960

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