US3884442A

US3884442A - Two post insulator support for utility poles

Info

Publication number: US3884442A
Application number: US510599A
Authority: US
Inventors: John E Breeden; Robert E Lane
Original assignee: Hopeman Brothers Inc
Current assignee: Hopeman Brothers Inc
Priority date: 1974-09-30
Filing date: 1974-09-30
Publication date: 1975-05-20
Anticipated expiration: 1992-05-20

Abstract

A cross-arm of folded sheet aluminum is provided with insulator supporting elements at each end formed from two overlapping tabs. The cross-section of the cross-arm is in the form of an inverted L with one additional element extending downwardly from the horizontal part of the L and another additional element extending horizontally away from the vertical part of the L in the same direction as the horizontal part of the L. These additional elements are welded to the outermost of the overlapping tabs along their edges to produce optimum strength. The additional element extending downwardly from the horizontal part of the L is also welded to the innermost of the overlapping tabs.

Description

United States Patent 1191 Breeden et al.

1 51 May 20, 1975 [54] TWO POST INSULATOR SUPPORT FOR 3,643,009 2/1972 Collister 174/45 R UTlLITY POLES 3,671,002 6/1972 Elliott et al. 248/221 [75] Inventors: John E. Breeden; Robert E. Lane, Primary Examiner Roy D Frazier both of Royston Assistant Examiner-Robert A. l-lafer [73] Assignee: Hopeman Brothers, Inc., New York, Attorney, Agent, or FirmSmith, Harding, Earley &

N.Y. Follmer [22] Filed: Sept. 30, 1974 [21] App]. No.: 510,599 [57] ABSTRACT A cross-arm of folded sheet aluminum is provided with insulator supporting elements at each end formed 52 US. Cl 248/221; 248/300; 174/45 R f two overlapping {aim The cross secfion f the [51] Int. Cl. F16m 13/02 cross arm is i the f f an inverted L with one 1 Fleld of Search 248/221 65; ditional element extending downwardly from the hori- 52/40 697, 721; 174/45 R, 149 R; 220/62, zontal part of the L and another additional element 68; 229/32, 37 R; 113/116 HH, 116 P, 120 extending horizontally away from the vertical part of E, 120 G the L in the same direction as the horizontal part of the L. These additional elements are welded to the References Cited outermost of the overlapping tabs along their edges to UNITED STATES PATENTS produce optimum strength. The additional element ex- 2,191 291 2/1940 Smith 229/32 tending downwardly from the horizontal P of the L 2544333 3 1951 229/32 is also welded to the innermost of the overlapping 2,884,670 5/1959 Garrison et al. 1 248/221 tabs. 3,499,973 3 1970 Barnes 174/45 R 3,568,968 3 1971 Taylor 248/221 5 Clams, 5 Drawing Flames 3 86 1 94 I0 5 1 I 1 I l 2o @Llz 22 I I P l 1 l I i I v I M1 l i PATENTED MY 2 01975 SHEET 1 0F 3 m M/ v. 1 M 5: is; v0. 1: w 6

FIG.

(to e2 1:2

FIG. 3.

TWO POST INSULATOR SUPPORT FOR UTILITY POLES BACKGROUND OF THE INVENTION This invention relates to insulator supports for utility poles, and particularly to a metal two-post insulator support of narrow profile design.

The vast majority of utility poles in the United States are provided with braced wooden cross-arms, having insulators extending upwardly from the upper side thereof for supporting electrical power lines. Since wood is becoming increasingly expensive, efforts are being made in the direction of using metal insulator supports on new poles, and eventually replacing wooden insulator supports with metal supports.

Another factor which has influenced the trend toward metal insulator supports is the expense of acquiring right-of-way. The shorter the overall dimension of the horizontally extending members of a utility pole the less expensive the right-of-way becomes. Even a few inches are significant. This consideration has led to the so-called narrow profile design, which is characterized by the fact that insulators are mounted to extend outwardly from the ends of the cross-arm, thereby providing the maximum spacing between power lines, while occupying a minimum right-of-way.

By itself, wood is unsuitable for use in narrow-profile cross-arms, because insulators cannot be adequately secured to the ends of a longitudinally cut piece of timber. While it has been proposed to provide wooden cross-arms with metallic end members for securing outwardly-extending insulators, such construction is rather elaborate, and somewhat unsatisfactory from that point of view, and also because of the relatively high expense of the wooden parts.

As all-metal, narrow-profile, insulator support, which is presently in use in some locations, has a relatively simple structure, in that it consists of an essentially rectangular, elongated loop of galvanized steel, one of the long sides being bent to fit the utility pole, and the short sides having outwardly extending insulators mounted thereon. This structure tends to rotate in a vertical plane under unbalanced vertical loads, so that utility companies have made a habit of waiting until it is determined in which direction the support will rotate, and then limiting further rotation by inserting a bolt into the utility pole at a position such that it will prevent further rotation of the insulator support. More importantly, however, is the inability of this type of insulator support to resist longitudinal forces exerted through the power lines. Furthermore, there is a tendency for the insulator post to bend the end of the loop in which it is mounted. This'is avoided by using a sufficiently heavy piece of metal to form the loop. But, the entire loop then must be of this same thickness, leading to a waste of metal.

In accordance with the present invention, a two-post insulator support for utility poles is provided, comprising an elongated cross-arm formed from a unitary sheet of metal having: a first elongated rectangular element adapted to be situated with its long dimension extendthe second element so that said elements form an elongated member having an L-shaped cross-section substantially throughout its length; a first pair of rectangular tabs integral with and perpendicular to the first elongated rectangular element, said tabs extending from the ends of the first elongated rectangular element in the same direction as the second elongated element extends from the first elongated element; and a second pair of rectangular tabs integral with and perpendicular to the second elongated rectangular element, said tabs of the second pair extending from the ends of the second elongated rectangular element in the same direction as the first elongated element extends from the second elongated element; the tabs at each end of the cross-arm overlapping each other and having aligned openings for retaining an insulator post.

The overlapping tabs provide high-strength supports for the insulator posts without requiring excessive amounts of metal in the remainder of the cross-arm. Furthermore, the overlapping construction of the tabs is very easily achieved in a cross-arm having integral mutually perpendicular elements for resisting both horizontal and vertical loads.

The principal object of the invention, therefore, is to provide a metal, narrow profile insulator support having high strength and light weight, and being simple to manufacture. Other objects and features of the invention will be apparent from the following detailed description, when read in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of a two-post insulator support in accordance with the invention, shown mounted on a utility pole;

FIG. 2 is a side elevation of the insulator support, as viewed from the right-hand side of FIG. 1;

FIG. 3 is an elevational view of a flat piece of sheet metal from which the cross-arm of the insulator support is formed, showing, in broken lines, the lines along which the various elements are folded;

FIG. 4 is a top plan view of the cross-arm and pole gain of the insulator support, before welding; and

FIG. 5 is a front elevation of the cross-arm and pole gain before welding.

DETAILED DESCRIPTION FIGS. 1 and 2 provide an overall view of the insulator support in accordance with the invention as installed on a utility pole 6. The insulator support consists of two principal parts. A pole gain 8 is designed to fit utility poles of various dimensions to prevent rotation of the cross-arm 10 which is secured to gain 8.

Bolts

12 and 14 secure the insulator support to pole 6.

Insulators

16 and 18, respectively having

posts

20 and 22, are secured to the opposite ends of cross-arm 10.

The construction of cross-arm 10 will be best appreciated from a consideration of the flat sheet of metal from which it is formed, preferably by means of a sheet metal brake. As shown in FIG. 3, taking into consideration the fold lines, the cross-arm consists essentially of eight parts: a first elongated rectangular element 24, a

second elongated rectangular element 26, a third elongated rectangular element 28, a fourth elongated rectangular element 30, a first pair of

rectangular tabs

32 and 34, at the opposite ends of member 24, and a second pair of

rectangular tabs

36 and 38, located at the opposite ends of rectangular element 26. Elongated

members

24, 26, 28 and 30 are all nearly the same length, slight differences existing in order to allow for overlapping of the rectangular tabs when the sheet of metal is folded into its final form.

The cross-arm is formed from the flat sheet shown in FIG. 3' by folding

members

30 and 28 and

tabs

32, 34, 38 and 36 all in the same direction so that they are essentially perpendicular with respect to the plane consisting of

elements

24 and 26, and then folding

elements

24 and 26 to a perpendicular relationship with respect to each other in a direction so as to form a partially closed elongated box. Of course, the folds need not be made in the order just described. The result of the folding of the sheet of metal in FIG. 3 is depicted in FIGS. 4 and 5, which show the cross-arm along with the pole gain to which it will be attached. The crossarm is in the form an elongated rectangular box having an elongated opening generally designated 40, extending from edge 42 of the third elongated member 28 to edge 44 of the fourth elongated member 30. This opening provides access to bolt hole 46, which consists of two aligned holes, one in element 26, and the other in the pole gain 8. Opening 40 also insures that the cross-arm will not collect water.

As shown in-FIG. 5, aligned

holes

48 and 50 in tabs. 34 and 38 are provided for one insulator post, and similar aligned

holes

52 and 54 in

tabs

36 and 32 are provided for the other insulator post, the insulators being mounted as indicated in FIG. 1. The nut on the insulator post clamps the tabs together, providing a firm support consisting of two thicknesses of metal. A single thickness of metal is adequate for the remainder of the cross-arm, because the mutually perpendicular relationship of its elements provides adequate strength against both vertical and horizontal loads.

Welds are preferably provided along the short edges of the narrow

elongated elements

28 and 30, securing them to the adjacent parts of

rectangular tabs

32 and 34. Thus, as shown in FIG. 1, welds are provided at 56 and 58. Referring to FIG. 3, weld 56 secures edge 60 of elongated element 30 to edge 62 of tab 32. Similarly, weld 58 secures edge 64 of element 30 to edge 66 of tab 34. In addition,

welds

56 and 58 may be extended slightly to secure elongated element 30 to

tabs

36 and 38. This extension is shown in FIG. 1 at the lower ends of

welds

56 and 58.

Referring again to FIG. 3,

edges

68 and 70 of element 28 are welded respectively to

edges

72 and 74 of

tabs

32 and 34. These welds are shown in FIG. 1 at 76 and The pole gain, as best shown in FIGS. 4 and 5, is formed from a single sheet of metal having

end elements

80 and 82 in contact with and extending perpendicularly away from element 26, and having a middle portion 84 which is bent inwardly so that it also comes into contact with element 26 of the cross-arm and forms a recess adapted to grip the surface of a utility pole in such a way as to resist rotation.

As indicated in FIG. 1, the pole gain 8 is welded to the cross-arm at six locations, welds being indicated at 86, 88, 90, 92, 94 and 96.'

Preferably, the insulator support is made entirely of heavy gage aluminum, and the welding maybe accomplished by well-known Heliarc, magnesium-inert gas, or tungsten-inert gas techniques.

From the foregoing, it will be appreciated that the two-post insulator support in accordance with the in- 4 vention is extremely simple in construction and light in weight while it has sufficient strength to withstand heavy vertical and horizontal loads, primarily as a result of the fact that the cross-arm comprises mutually perpendicular elements having overlapping tabs forming the insulator supports.

We claim:

1. A two-post insulator support for utility poles comprising an elongated cross-arm formed from a unitary sheet of metal having:

a first elongated rectangular element adapted to be situated with its long dimension extending in the horizontal direction;

a second elongated rectangular element, integral with and perpendicular to the first elongated element, said first and second elements being of nearly equal length and one long edge of the first element being integrally joined with a long edge of the second element so that said elements form an elongated member having an L-shaped crosssection substantially throughout its length;

a first pair of rectangular tabs integral with and perpendicular to the first elongated rectangular element, said tabs extending from the ends of the first elongated rectangular element in the same direction as the second elongated'element extends from the first elongated element; and

a second pair of rectangular tabs integral with and perpendicular to the second elongated rectangular element, said tabs of the second pair extending from the ends of the second elongated rectangular element in the same direction as the first elongated element extends from the second elongated element;

the tabs at each end of the cross-arm overlapping each other and having aligned openings for retaining an insulator post.

2. A two-post insulator support according to claim 1 including a third elongated rectangular element integral with the second elongated element, said second and third elongated elements being of nearly equal length and one long edge of said third elongated element being integrally joined with the second elongated element along the edge of said second elongated element opposite the edge to which the first elongated element is integrally joined, and said third elongated element extending perpendicular to the second elongated element in the same direction as the first elongated element extends from the second elongated element, the third elongated element being welded along one of its short edges to an edge of one of said first pair of rectangular tabs, and along the other of its short edges to an edge of the other of said first pair of rectangular tabs.

3. A two-post insulator support according to claim 2 including a fourth elongated rectangular element integral with the first elongated element, said first and fourth elongated elements being of nearly equal length and one long edge of said fourth elongated element being integrally joined with the first elongated element along the edge of said first elongated element opposite the edge to which the second elongated element is integrally joined, and said fourth elongated element extending perpendicular to the first elongated element in the same direction as the second elongated element extends from the first elongated element, the fourth elongated element being welded along one of its short edges to an edge of one of said first pair of rectangular tabs,

rectangular element, and in which the short dimension of the fourth rectangular element is less than the short dimension of the second rectangular element, whereby the cross-arm is in the form of an elongated rectangular box having an elongated opening extending from an edge of the third elongated member to an edge of the fourth elongated member.

Claims

1. A two-post insulator support for utility poles comprising an elongateD cross-arm formed from a unitary sheet of metal having: a first elongated rectangular element adapted to be situated with its long dimension extending in the horizontal direction; a second elongated rectangular element, integral with and perpendicular to the first elongated element, said first and second elements being of nearly equal length and one long edge of the first element being integrally joined with a long edge of the second element so that said elements form an elongated member having an L-shaped cross-section substantially throughout its length; a first pair of rectangular tabs integral with and perpendicular to the first elongated rectangular element, said tabs extending from the ends of the first elongated rectangular element in the same direction as the second elongated element extends from the first elongated element; and a second pair of rectangular tabs integral with and perpendicular to the second elongated rectangular element, said tabs of the second pair extending from the ends of the second elongated rectangular element in the same direction as the first elongated element extends from the second elongated element; the tabs at each end of the cross-arm overlapping each other and having aligned openings for retaining an insulator post.

3. A two-post insulator support according to claim 2 including a fourth elongated rectangular element integral with the first elongated element, said first and fourth elongated elements being of nearly equal length and one long edge of said fourth elongated element being integrally joined with the first elongated element along the edge of said first elongated element opposite the edge to which the second elongated element is integrally joined, and said fourth elongated element extending perpendicular to the first elongated element in the same direction as the second elongated element extends from the first elongated element, the fourth elongated element being welded along one of its short edges to an edge of one of said first pair of rectangular tabs, and along the other of its short edges to an edge of the other of said first pair of rectangular tabs.

4. A two-post insulator according to claim 3 wherein the short edges of the fourth elongated element are also welded to said second pair of rectangular tabs.

5. A two-post insulator support according to claim 3 in which the short dimension of the third rectangular element is less than the short dimension of the first rectangular element, and in which the short dimension of the fourth rectangular element is less than the short dimension of the second rectangular element, whereby the cross-arm is in the form of an elongated rectangular box having an elongated opening extending from an edge of the third elongated member to an edge of the fourth elongated member.