US2688654A - Insulator for fence posts - Google Patents

Description

p 7, 1.954 A. B. BUSSMANN, JR 2,688,654

INSULATOR FOR FENCE POSTS Filed Oct. 10, 1949 ATEORAZE'Y Patented Sept. 7, 1954 UNITED STATES PATENT OFFICE INSULATOR FOR FENCE POSTS Aloysius B. Bussmann, Jr., St. Louis, Mo. Application October 10, 1949, Serial No. 120,481

1 Claim.

This invention relates to improvements in insulators. More particularly this invention relates to improvements in insulators which electrically isolate electrified wires from supporting posts.

It is therefore an object of the present invention to provide an improved insulator which can electrically isolate an electrified wire from a supporting post.

In raising animals it is frequently desirable or necessary to confine the animals to definite grazing areas; and such confinement is usually effected by a fence or fences. While many different types of fences can be used, electrified fences are preferable because they can be easily erected and moved and can confine the animals safely and surely. Electrified fences usually consist of lightweight metal or wood posts which support insulators; the insulators in turn supporting electrified wires. The insulators of an electrified fence are intended to maintain the electrified wire in assembled relation with the fence posts while electrically isolating that wire from those posts; the efficiency of the electrical insulators in preventing leakage of current to the fence posts being an important measure of their value.

The insulators can be made with considerable thickness and of a hard insulating material, and.

y when so made they will have sufficient electrical resistance to isolate the electrified wire from the fence posts. As long as the surfaces of such insulators are dry and clean, those insulators can effectively isolate the electrified wire from the fence posts; the resistance of the insulating material preventing passage of current through the bodies of the insulators, and the dry clean surfaces of the insulators preventing leakage of current along those surfaces. However, when the surfaces of the insulators become dirty and wet, as they will do because of dust and rain, the water and dust tend to form paths along the surfaces of the insulators that can conduct current. Such conduction reduces the voltage of the electrified wire and reduces the utility of the electrified fence. To minimize any such conduction, the in sulators should be made as elongated bodies, and the electrified wires should be held in grooves adjacent those ends of the insulators which are remote from the fence posts. This arrangement increases the length and resistance .of the current leakage path along the surface of the insulator.

Insulators of this type could be used successfully except for the fact that the fasteners for those insulators act to decrease the ability of those insulators to prevent conduction of current v from the electrified wire to the fence posts. For example, the great majority of those insulators are secured to the fence posts by nails, bent wires, or bolts which pass through axially-directed openings in the insulators; the heads of the nails or the loops of the wires or the nuts for the bolts bearing against the outer ends of the insulators and. forcing those insulators against the fence posts. The heads of the nails or the loops of the wires or the nuts for the bolts will be rather close to the electrified wire supported by the insulators, and it will not be long before dust, rust from the nails or wires or bolts, or tanning solution leaching from the leather washers used with the nails, will provide current leakage paths from the nail heads or wire loops to the electrified wire; such current leakage paths conducting cur rent from the electrified Wire to the fastener, and the fastener conducting that current to the post. Those current leakage paths will thus vitiate the electrical isolation thought to be provided by the elongation of the insulators and by the holding of the electrified wires at those ends of the insulators which are remote from the fence posts. The present invention obviates such current leakage paths and yet attains intimate and positive securement of the insulators to the fence posts by providing insulators which are held by fasteners that do not extend through to those ends of the insulators which are remote from the fence posts.

The use of fasteners which do not extend through to those ends of the insulators which are remote from the posts is additionally advanta geous because it minimizes electrical breakdown of the insulating material in the bodies of the insulators. In the large majority of insulators used on electric fences today, the thickness of insulating material between the electrified wire and the fastener is at a minimum; the forming of the groove in the surface of the body reducing that thickness. As a result, unless the insulating material between the wire-receiving groove and the opening that receives the fastener is completely free of voids or cracks, and unless the glazes on the surfaces of said groove and opening are perfect, current can pass through to the fastener from the electrified wire. All of this is avoided by the present invention since the fastener is axially, as well as radially, spaced from the wire-receiving groove. The shortest straight line distance between a wire in the groove and a fastener in the opening is not through the thin portion of the insulator adjacent the groove, but is through the thick portion of the insulator. Moreover, that straight line distance is along a line inclined to the axis of the insulator and is thus much longer than the wall thickness of that insulator. I

The insulators provided by the present invention have seats therein, which receive the fasteners and enable those fasteners to secure the insulators to the fence posts; and those seats,

are spaced from the electrified wire distances, along the surfaces of the insulators, equal to or greater than the distances between the electrified wires and the fence posts. With these insulators, the securement of the fasteners to the insulators and to the fence posts will not detract from the ability of the insulators to electrically isolate the electrified wire from the fence posts; the surface distance along each insulator between the post and the electrified wire being a principal determinant of the isolating efficiency of the insulator. It is therefore an object of the present invention to provide an insulator with a seat therein which can receive a fastener and which is as far from the electrified wire as the electrified wire is from the post.

The electrical isolation of the fastener relative to the electrified wire is further assured by providing a number of abrupt changes of curvature in the surface of the insulator between the electrified wire and the seat for the fastener and between that wire and the post. These changes of curvature increase the length of any electrical paths between the electrified wire and the fastener or the post without increasing the overall length of the insulator. Thus, increased electrical efficiency is attained without any increase in the amount of insulating material used in the insulator. It is therefore an object of the present invention to provide a number of abrupt changes of curvature in the surface of an insulator between the electrified wire carried thereby and the post or the seat for the fastener used with the insulator.

The outer end of the fastener used with the insulator provided by the present invention will be spaced wholly within the body of the insulator. That end of the fastener will be lodged in the opening which extends to theouter surface of the insulator, and that end of the fastener will be largely spared from direct contact with rain, sleet, ice and snow. Consequently, that end of the fastener will have less tendency torust than will the ends of fasteners which project out of the insulators. This. not only assures a longer life for the fastener but it also minimizes the amount of rust that could adhere to the surface of the insulator and provide a current leakage path. It is therefore an object of the present invention to provide an insulator wherein the outer end of the fastener is disposed wholly within the body of the insulator.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

In the drawing and accompanying description a preferred embodiment of the present invention is shown and described but it is to be understood that'the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claim.

In the drawing, Fig. l is an end view of an insulator that is made in accordance with the principles and teachings of the present inven- Fig. 2 is a side elevational view of the insulator shown in Fig. 1, I

Fig. 3 is a cross sectional side view of the insulator of Figs. 1 and 2, and it shows how that insulator can be secured to a fence post by an eye-bolt fastener,

Fi 4 is a side elevational view of the insulator, fastener and post of Fig. 3,

Fig. 5 is a cross sectional side view of the insulator of Figs. 1 and 2, and it shows how that insulator can be secured to a wooden post by a screw, and

Fig. 6 is a side elevational view of the insulator of Figs. 1 and 2, and it shows that insulator secured to a post of L-shaped configuration.

Referring'to: the drawing in detail, the numeral Hl generally denotes a body of insulating material. That body has a base l2 and a recess M extending into that base. The recess M has conical walls and a. fiat bottom; that recess having the form of a frustum of a. cone. Anv opening 6, of circular cross section, is provided at the geometric center of the body Hi, and that opening is contiguous with the recess Hi. The opening l6 opens out into a tapered circular opening 18; opening I8 extending to the other end of the body Hi. The opening 58 is preferably hexagonal in cross section, but that opening:

could be given a number of other circular cross sections. The opening l8 has a taper, and that taper makes the outer end of opening it larger than the inner end of that opening. The opening is and the opening. it define a. seat 28; that seat being intermediate the ends of the body It. The distance between the seat 2!) and the outer end of the body it is greater than one half the length of that body.

A circular rim 22 is provided on the end face at the left hand end of the body If], and that. rim constitutes an abrupt change of curvature from the interior of the opening it to a recess 24 of annular form in the left hand end of the body Ill. The change of curvature is almost one hundred and eighty degrees between the surface of the opening 18 and the outermost portion of the rim 22. A second abrupt change in curvature occurs at the junction of the rim 22 and the recess 24.

A wire-receiving groove 2 6 is provided adjacent the left hand end of the body H1, and that groove has six (6) fiat faces generally parallel with the six (6) flat faces of the circular opening 18. With this arrangement, the distance between the corresponding faces of groove 26 and opening 18, through the insulating material of body Hi, will be uniform, except for the effect of the taper of opening E8. The groove 26 coacts with the recess 24 to define an annular projection 28 at the left hand end of the body ID. This annular projection provides an abrupt change of curvature between the recess 2 and the groove 2.6. The wire-receiving groove 26 is adjacent the outer end of the body Hi, and it is disposed wholly outwardly beyond the seat 20.

A groove 30 and a groove 34 are provided in the exterior of the body Hi between the wire.- receiving groove 2:5 and the base I2. The grooves 30 and 34 define two annular projections 32 and 36; and the grooves 30 and 3t and the projections 32 and 36. constitute abrupt changes of curvature between the base I2 and the wirereceiving groove 26.

This construction provides a wire-receiving groove 26 which is spaced from the seat 20 and from the base I2. of the body Ill by substantial I straight-line distances and by substantial surface distances. The surface distances are greater than the straight-line distances because of the abrupt changes of curvature provided by rimv 22, recess 24, grooves 36 and 34, and annular projections 28, 32 and 36. As a. result, if current could leak from a. wire held in the wire-receiving groove 26 to the seat 26 or to the base I2 that current would have to travel a longer distance than the straight-line distance between the wire-receiving groove 26 and the base I2 or the seat 26. Of great importance is the fact that the seat 26 is disposed intermediate the ends of the body I6 and that the current leakage path from groove 26 to the seat 26 is equal to or longer than the current leakage path from groove 26 to the base I2, along the surface of body I6. Also of great importance is the fact that the wirereceiving groove is at that end of the body I6 which is remote from the post, while the seat 26 is at that end of body I6 which is adjacent the post.

This avoids the decrease in the efficiency of the insulator experienced with prior insulators wherein the fastener was adjacent the wire-receiving groove, or wherein the wire-receiving groove was too close to the post.

The opening I6 in the body I6 is dimensioned to receive the threaded portion of an eyebolt 38. The recess I4 extending inwardly from the base I2 is dimensioned to receive part of the curved portion of the eyebolt 38, and to permit that part of the curved portion to be drawn inwardly of the body I6. The circular opening I8 is dimensioned to snugly receive a nut 46 which can be threaded onto the threaded end of the eyebolt 38. To assemble the eyebolt 38 with the insulator, it is only necessary to insert the threaded end of the eyebolt 38 through the opening I6 while holding the body I6 in position so gravity will cause the nut 46 to fall to the bottom of the opening I8. It is then a simple matter to either hold the eyebolt 38 and rotate the body ID or to hold the body I6 and rotate the eyebolt 38. In either event, the threads on the end of the eyebolt 38 will engage the threads of the nut 46 and cause the nut 46 to be held in engagement with the eyebolt 38. Once the threads of the eyebolt 38 have engaged the threads of the nut 46, the eye of the eyebolt 38 can be telescoped over the top of a fence post 42. Thereafter the eyebolt 38 and the insulator can be moved downwardly until they reach the desired height, whereupon a few additional turns of the body ID will lock the eyebolt and insulator in position. At that time the nut 46 will be pressed firmly against the seat 28, and the eye of the eyebolt will tightly encircle post 42. Solid securement with the post 42 is assured because the recess I4 is dimensioned to receive part of the curved portion of the eye of the eyebolt, thus enabling that eye to provide loop contact with the post 42 while the post 42 has line contact with the opposite edges of the base I 2. This arrangement facilitates such a complete securement of the post and insulator that there is no danger of the insulator sliding down the post.

When pressed against the seat 26, the nut 46 will be spaced from the wire-receiving groove 26 a distance, along the surface of body I6, that is equal to or longer than the distance, along the surface of body III, between the wire-receiving groove 26 and the base I2. This means that the eyebolt fastener 38 does not in any way detract from the electrical isolation of the electrified wire from the post; a principal limiting factor to such electrical isolation being the distance along the surface of the body I6 between the wire in the groove 26 and the post 42. This is in sharp contrast with insulators which have axial openings that receive elongated nails or bent wires or bolts, because in those insulators the heads of the nails or the loops of the wires or the nuts for the bolts are closely adjacent the wire-receiving grooves and provide short leakage paths. Moreover, the nut 46 is spaced from the wire-receiving groove 26 by three abrupt changes of curvature: the first change of curvature being between the opening I8 and the rim 22, the second change of curvature being between the rim 22 and the recess 24, and the third change of curvature being between the recess 24 and the annular projection 28. Because the seat 26 is spaced from the wire-receiving groove 26 by a distance greater than the distance between that groove and the post 42, and because the seat 26 is spaced from the wire-receiving groove 26 by three abrupt changes of curvature, the electrical isolation of an electrified wire in groove 26 will not be reduced by the presence of a fastener pressing against the seat 20.

It should also be noted that the shortest straight line distance between a wire in groove 26 and a fastener in opening I8 is not through the thin wall adjacent groove 26. Instead, that straight line distance is through the thick wall portion of the body I6. Moreover, by being inclined to the axis of the body, that distance is much longer than the wall thickness of the body I6.

In the event rain, snow or ice is driven into the opening I8, that rain, ice or snow will run out because of the taper of that opening. Moreover, that taper will act to guide the nut 46 as it is dropped downwardly toward the seat 26. That taper would also guide a screw or nail dropped toward the seat 26.

The insulator provided by the present invention can be secured to posts by a wood screw, as shown particularly in Fig. 5. The seat 26 receives the head of a wood screw 44, and the threaded end of that wood screw will seat in a wooden post 46. In securing the insulator to the post 46, it is only necessary to turn the insulator so the opening I8 is vertically directed, drop the screw 44 into that opening with the threaded end downward, shake the insulator until the threaded end of screw 44 passes through the opening I6, and place a screw driver in the opening I8 so its blade will seat in the slot in the head of the screw 44. Thereafter, it is a simple matter to place the end of the screw 44 in engagement with the wooden post and rotate that screw until it bites into the wood of the post and pulls the base I2 of the insulator solidly against that post. The insulator could also be held against a wooden post by a nail, as by using a nail set to drive the nail home. In the case of the screw and the nail, the heads of those fasteners will press against the seat 26, thus being spaced from the wire-receiving groove 26 and being isolated from the electrified wire in that groove.

The insulator can be secured to posts of L- shaped configuration, as shown in Fig. 6. In that case, a J-bolt 48 is secured to the insulator by a nut, not shown, in the same manner as the eyebolt of Fig. 3 is secured to its insulator. However, the J of the J-bolt 48 does not encircle the post; instead it is set so it presses against one face of the post 56. The rotation of the insulator body I6 will tighten the nut on the threaded end of J portion of J-bolt 48 and will tend to lock the J portion of J-bolt 48in position against the post. In each instance, the fastener is spaced from the wire-receiving groove a surface distance equal to or longer than the surface distance between that wire-receiving groove and the post. This is due to the spacing of the seat intermediate the ends of the insulator.

Whereas a preferred embodiment of the present invention has been shown and described in the drawing and accompanying description it should beobvious to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

An insulator that is adapted to hold an elec trified wire in assemble-:1 relation with a support while electrically isolating said electrified wire from said support, said insulator comprising an elongated body of insulating material, said elongated body being of circular cross-section throughout the major portion of the length thereof and having alternating annular grooves and projections on the exterior of said major portion of the length thereof, a wire receiving groove in the exterior of said elongated body adjacent that end or said elongated body which is remote from the base of said elongated body, said wire receiving groove being spaced from said end of said elongated body by a smoothly rounded annular projection that extends radially outwardly beyond said wire receiving groove and being adjacent one of said annular projections in said major portion of the length of said elongated body, said one annular projection in said major portion of the length of said elongated body being smoothly rounded and extending radially outwardly beyond said wire receiving groove, said wire receiving groove having as the bottom thereof a plurality of contiguous planes constituting a prism, a passageway extending through said elongated body adapted to receive means for holding said elongated body in assembled relation with said support, said passageway being co-axial with the long axis of said elongated body and having three portions of difierent length and cross-sec tion throughout its length, one of said portions having as the wall thereof a plurality of contiguous planes forming a prismatic enclosure, the contiguous planes of said wall of the first said portion being substantially parallel to the said contiguous planes of said wire receiving groove, said first portion extending from said end of said elongated body a distance greater than half the length of said elongated body, a second of said portions being contiguous with said first portion and being of circular cross-section smaller than the cross-section of the first said portion, said second portion being short, a third of said portions being a recess that extends inwardly from said base of said elongated body and being of gradually decreasing cross-section and being contiguous with said second portion, said holding means extending through said third portion and said second portion and extending into said first portion when the insulator is holding said electrified wire in assembled relation with said support, said portions of said passageway forming a continuous imperforate wall for said passageway.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 836,122 Locke Nov. 20, 1906 927,321 Bond July 6, 1909 1,720,181 Kyle July 9, 1929 1,736,043 Kyle NOV. 19, 1929 2,191,171 Lee et a1. Feb. 20, 1940 2,440,748 Johnson May 4, 1948 2,450,730 I-Iord Oct. 5, 1948 2,468,907 Wilson et a1. May 3, 1949 FOREIGN PATENTS Number Country Date 146,911 Germany Dec. 19, 1903 161,092 Germany May 31, 1905 18,903 Denmark June 8, 1914

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