US2081974A - Cable suspension - Google Patents

Description

`une l, 1937. E E ARNOLD CABLE SUSPENSION Filed Jan. ll, 1935 n h@ 58m INVENTOR LUmT 30 from the bottom of a string Aof insulators.

Patented June y1, 1937 PATENT OFFICE CABLE SUSPENSION` Edwin E. Arnold, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a.l corporation of- Pennsylvania Application January 11, 1935, Serial No. 1,292

8 Claims.

The present invention relates to suspension devices for electrical transmission lines and more particularly to a device which permits cable vibrations to pass freely through it, thereby minimizing the possibility .of breakage of the cable due to molecular fatigue.L

In suspension devices of the prior art, it has been usual practice to grip or clamp the conducting cable at or in the supporting shoe which,

10 in turn, is secured to the bottom of a string of insulating units. With such construction, however, vibrations in the cable in a vertical plane cause a bending of the cable at the point of clamping which eventually results in molecular v fatigue of the cable strands and consequent breakage thereof.

In Patent No. 2,005,881 issued June 25, 1935 to E. E. Arnold and C. L. Fortescue, and assigned to the Westinghouse Electric & Manufacturing Company, a construction is shown which has proved to'y be quite successful in practice but Alife tests have indicated a number of desirable changes to increase its eiilciency. Accordingly, the object of the present invention is to improve the construction shown in said patent.

According to the present invention, a resilient strip is disposed beneath the cable longitudinally thereof and is supported adjacent its midpoint by a shoe which, in turn, is pivotally supported` The ends of the stripare clamped to the cable in a particular manner and pads or liners of a `material softer than that of the cable are interposed4 between the cable and the resilient strip and between the cable and the end clamps. In addition, means are provided to insure that various elements of the assembly are maintained in proper operating relation under normal service conditions and there are a number of structural features to improve the assembly over that shown in the aforesaid Patent No. 2,005,881, as pointed out hereinafter.

Referring to the drawing,

Figure l is a view in elevation, partly in sectuting part of the present invention,

Figs. 4 and 5 are views in plan and vertical section, respectively, of a clamping 'shoe for cooperation with the shoe shown in Figs. 2 and 3,

Fig. 6 is a view in perspective of a clamping device for the shoes shown in Figs. 2 through 5,

(C l.l 173-251) Fig'. 10 is a fragmentary view of a portion of Fig. 1, Y

Fig. 11 is a plan view] of a clamping strap shown in Fig. 1, and

Fig. 12 is a view on a reduced scale of a vertical section taken on the line )UI- XII oi' Fig. 1.

Referring more specifically to the drawing and particularly Fig."y 1 thereof, the invention contemplates a supporting clamp for y.a stranded cable I including an elongated strip 2 of resilient material, such as spring steel, which extends below the cable I longitudinally thereof.

A supporting shoe 4 embraces the strip 2 substantially at the midpoint of the latter, and includes a central depressed portion for receiving a' I through 9. It is provided with a longitudinally extending channel which conforms more or less to the curvature of ,the cable I and has. depending ears 'I adapted to straddle the lateral center line of the shoe 4.

The materia of which the liner s is formed .l

may be any of the so-calledv synthetic rubber compounds which show substantially no deterioration under varying weather conditions', and I have found that a suitable compound is a stable isoprene derivative of the chlorinated type known commercially as Duprene.

The surfaces of the depression in the shoer4, the deformed portion of the strip 2 and the cori-` tour of the ears 'l are so related that the strip 2 and liner 6 are substantially nested in the depression in the shoe to prevent /relative movement therebetween axially of the conm ductor I.

A supporting stirrup I0 having a suitable sup- .porting socket Il at the upper end thereof is adapted to straddle the shoe 4 and is pivoted thereto by a bolt l2. The point of pivotal support is substantially coaxial with the arc formed by the depending ears 'I on the. strip 6 and the bolt I2 extending through the clamp betweensuch ears aifords additional means for maintaining the elements` 2, I and 6 in operative position. It is to be noted thatwith the bolt I2 in position, the strip 2 cannotwbe removed therefrom in either a vertical or horizontal direction.

Clamping shoes Il and I6, of a relatively light weight material, such as an aluminum alloy, having grooved inner surfaces, substantially conforming to the curvature of the cable I, are clamped to the cable adjacent to the free ends of the strip 2 by U-bolts I8 of the form shown in Fig. 6. Each free end ol the strip 2 is disposed between a U-bolt I8 and a lower clamping shoe I8, and is provided with punched portions, as shown in Fig. 10, providing at each end of the strip a depression in the upper face thereof, and a lug on the lower face thereof.

A suitable aperture or depression I9 is provided in the bottom of the U-boli; I l to receive the lug on the lower face of the strip 2, and alug on the under face of the lower shoe I6 adapted to be received within the recess formed in the upper face of the strip 2. These intertting deformed portions on the shoe I6, strip 2, and U-bolt I8 maintain these elements in proper operative relation and prevent relative movement therebetween in a direction longitudinally of the strip 2 under operating conditions.

The threaded ends of the U-bolt I8 project through suitable openings 20 cast into the upper clamping shoe, and the arms of the U-bolt I8 extend between projections 2l cast in the lower clamping shoe.

By reason of the clamping construction heretofore described, a single U-bolt I8 is suillcient to exert an eiilcient clamping force whereby all of theelements are maintained in proper operative position and the strip 2 securely clamped to the conductor.

It has been found in practice that, with clamping shoes of the usual type, there will be some abrasion of the conductor strands between the two shoes Il and Ii. In order to avoid this condition, it is proposed in the present invention to provide a liner on the surfaces of the shoes which contact with the conductor I. In a preferred form, the liner may be of a metal or alloy somewhat softer than the metal of the cable or it may be of some rubber-like composition which is sumclently impervious to weather and temperature conditions, such as a material similar to that of the liner 6. Such material is sufficiently hard and dense to withstand the rather severe strains' imposed upon it but is suillciently soft'to permit the cable strands to become slightly imbedded in it, to thereby increase the clamping area of the shoes Il and I6.

Referring to Figs. 3 and 5, a liner 22 substanrial, It ls, durable to Novlde an electrical con nection between the cable and the shoe members to bring these elements to the same elec trical potential. The plugs 24, therefore, serve the dual purpose of maintaining the liners 22 in position and affording a direct electrical connection between the cable and shoe elements, thereby eliminating the possibility of an electrical discharge between the parts with attendant interference to radio reception.

Tests on a cable suspension, as above de scribed, indicate that as vibrations pass along the cable, there is a tendency for the cable to touch the strip 2 along an area between the clamp Il, I6 andthe supporting shoe l. Under cases of severe vibration, the cable hits the strip with sufficient force to deform the strands of the cable and in order to alleviate this condition an auxiliary clamping device is provided ior limiting the vertical movement of the cable with respect to the strip, and for spacing the cable from the strip. This device includes a strap of soft sheet material, such as aluminum, as shown in Fig. 11, having a tongue portion 26 and a body portion having apertures 2l and 2l therein, adapted to be wrapped around the cable, strip 2, and a spacing element l0 between the strip 2 and cable.

The spacing element 20 compris a block of material softer than that of the cable, and-may be of the same material as the liner i or 22. The block has a grooved upper surface for receiving the cable I, and a ilat bottom surface with a centrally disposed lug 2l.

At the point where the auxiliary clamping device is to be disposed, the strip 2 has a punched or deformed portion oi the same general character as shown in Fig. 10, to provide a depression on the upper face of the strip and a lug 2l on the 'under surface thereof. The depression is adapted to receive the lug 3l of the spacing element 30, and the lug '2l is adapted to project through aperture 28 in the strap shown in Fig. 11, when the strap` is wrapped around the cable with its tongue 2B drawn through the opening 21 and return-bent upon itself, to maintain the block 30, cable and strip 2 inoperative relation.

When the suspension is installed for service on a transmission" line, damaging vibrations occurring on the cable usually occur in a vertical plane and by reason of the fact that the cable isv clamped. at widely spaced points to the resilient strip 2, such vibrations may pass relatively freely through the suspension device; the portion of the cable extending through the light-weight shoe l being free to move vertically between' the arms of the saddle III. Because of the liner 6 of relatively soft material and the block Il of similar material there will be no pounding of the cable against the hard metal parts of the support thereby insuring longer life of the cable. In addition', because of the peculiar and novel construction of the clamps for the end of the strip 2, there will be no relative slipping between the cable and the strip 2 at these points of clamping.

It should be apparent from the foregoing, that the suspension device above descri is a distinct improvement over the prior ncluding that represented by Patent No. 2,005,881, above referred to, and it has been found in practice that fuomsndansedreamszmumitanmnmube Si f placed thereon except as imposed by the prior art and the appended claims.

l I claim as my invention:

1. A suspension device for cables comprising an elongated strip of spring material for disposition beneath the cable longitudinally thereof, means for rigidly clamping the ends of said strip to the cable, a shoe engaging substantially the midpoint of said strip in supporting relation, means for pivotally supporting said shoe, a spacing member of softer material than said cablebetween said strip and cable within said shoe, and correspondingly shaped portions on said spacing member, strip and shoe interfitted to prevent relative displacement therebetween in a direction parallel to the cable axis.

2. A suspension device for cables comprising an elongated strip of spring material `for disposition beneath the cable longitudinally thereof, means for securing the ends of said strip to the cable, a shoe engaging substantially the midpoint of said strip in supporting relation, means for pivotally supporting said shoe, a spacing member of amaterial softer than said cable between `said strip and cable within said shoe, correspondingly shaped portions o-n said spacing member, strip and shoe interfitted to prevent relative displace.

ment therebetween in'a direction parallel to the cable axis, and means comprising a part of said pivotal supporting means extending between the strip and spacing member for preventing displacement of said strip with respect to said shoe in a direction perpendicular to the axis of said cable.

3. A suspension device for cables comprising an elongated strip of resilient material for disposition beneath the cable longitudinally thereof, a shoe engaging substantially the midpoint of said strip in supporting relation, means for pivotally supporting said shoe includingl means for maintaining said strip in operative position, means for clamping the free ends of said strip to the cable each includingr a clamping shoe disposed between the strip end and the cable, a clamping device embracing the strip end, shoe and cable, and interfitted portions on said shoe and strip for preventing relative-movement therebetween in a direction longitudinally of the strip.

A suspension device for a cable comprising an elongated spring strip for dispdsitlon beneath the cable substantially parallel thereto, support ing means engaging the midpoint of said strip and free of the cable, and clamps for securing the free ends of said strip to the cable each comprising a lower shoe and an upper shoe embracing the cable, clamping means surrounding the end of said strip and the lower shoe, and deformed portions on said lower shoe and strip end in interiitting engagement.

5. A suspension device lfor a cable comprising an elongated strip for disposition beneath the cable substantially parallel thereto, supporting means engaging the midpoint of said strip and free of the cable, and clamps for securing the free ends of said strip to the cable each comprising a lower shoe and an upper shoe embracing the cable, clamping means 'surrounding the end of said strip and the lower shoe, and deformed portions on said lower shoe and strip end in intertting engagement, said shoes being lined with a material softer than that of the cable in engagement with the cable.

6: A suspension device for a cable comprising an elongated strip for disposition beneath the cable substantially parallel thereto, supporting means engaging the midpoint of said strip and free of the cable, and clamps for securing the free ends of said strip to the cable each comprising a lower shoe and an upper shoe embracing the cable', clamping means surrounding the end of said strip and the lower shoe, and deformed portions on said lower shoe, strip end, and clamping means in nestedrelation for preventing relative movement therebetween in a direction parallel to the cable axis.

7. A clamp for an electrically conducting cable comprising upper and lower clamping shoes adapted to embrace the cable, and means for clamping them in such position, said shoes having a lining ofldielectric material softer than the material of the cable in engagement with the cable, and means,.establishng an electrical connection between said shoe and cable through said dielectric lining.

8. In a clamp for an electrical cable including a clamping shoe, a resilient pad of dielectric material for disposition between said shoe and cable, means for securing said pad to the shoe including a metallic member of a material softer than that of the cable constituting an electrical connection between said shoe and cable extending through the dielectric pad.

EDWIN E. ARNOLD.

Images