Lightweight Line Tower Kit

The support of relatively high tension power conductors particularly in congested areas presents serious problems owing in major part to restrictions imposed by the local environment. Tower structures ranging in heights from fifty to one hundred and twenty five feet are customarily required and oftentimes the foundation area is very restricted or is located near other structures rendering it difficult to bring in heavy duty erection equipment or to utilize conventional tower structure. Three types of structures are in general use, namely wooden poles. steel poles and reinforced tower structures. Wooden poles are the least expensive but their erection in restricted areas often imposes serious problems and hazards. Wooden poles have a limited life even under favorable conditions and, under unfavorable conditions, have an undesirably short life. Concrete and steel towers can be assembled at the site but are extremely costly and require the use of equipment oftentimes difficult to bring to the site. Furthermore the cost can be excessive and typically fifteen to twenty times the cost of a wooden pole.

The present invention avoids the serious shortcomings and disadvantages of prior practice including those referred to above and others well known to those skilled in this art. To this end there is provided a kit of low cost lightweight modular components of unusually long life readily and inexpensively installable by simple equipment. The two major components of the kit include a preassembled unclimbable unit and one or more preassembled climbable units rigidly securable together in end-to-end relation. A variety of auxiliary components are selectively attachable to the modular tower units to support power conductors in a wide variety of well known and commonly employed patterns. All major components are desirably formed of high strength aluminum alloy anchorable to the tower units by threaded fasteners. The preassembled modular units include a plurality of extruded corner members interconnected directly to one another by welding or by spanner plates. The unclimbable unit includes generally imperforate spanner plates whereas the climbable units are interconnected by cross pieces functioning additionally as climbing steps for workmen.

A feature of the invention is the joint construction for connecting the units together. The joint is made by abutting the units end-to-end and securing thereto couplings that overlap portions of the length of the units adjacent their abutting ends. Preferably, the couplings and the overlapping surfaces of the tower units have teeth that mesh to lock the couplings in place and thereby resist shear forces exerted on the couplings.

The power conductors may be supported from the tower while suspended from the outer ends of cross arms or from the outer ends of cantilever supported insulators. In some instances it may be desirable to employ a pair of towers in side by side relation interconnected by cross ties or bracing with the power conductors suspended from a cross arm interconnecting the upper ends of the two towers.

The invention towers also are equally suitable for other uses encircling a dead end support for power conductors.

Accordingly, it is a primary object of this invention to provide a unique kit of components including a plurality of factory fabricated tower modules adapted to be readily assembled at an installation site in a minimum of space and with a minimum of simple equipment.

Another object of the invention is the provision of a kit of lightweight, corrosion resistant metal components readily assembled in the field into a power line support of a desired height utilizing prefabricated modular tower units.

Another object of the invention is the provision of a modular tower unit of tubular cross section formed from a plurality of extruded metallic elements including means rigidly interconnecting the same.

Another object of the invention is the provision of a low cost load carrying tower structure adapted to be erected in the field from factory preassembled modular units including at least one unclimbable lower unit and one or more climbable upper units rigidly interconnectible in end-to-end relation.

Another object of the invention is the provision of a kit of lightweight high strength components selectively interconnectible at a power line site in any of a wide variety of ways.

Another object of the invention is the provision of a kit of components including factory preassembled units, various combinations of which are selectively adapted for assembly in the field to provide a supporting structure to suit the requirements of a particular location.

Another object of the invention is the provision of a kit of modular tower components adapted to be interconnected in the field and including components selectively attachable to the upper end of the tower to support power line insulators in suspension, tension and cantilever fashion.

Another object of the invention is the provision of a modular tower structure formed from a plurality of extruded members interconnected in a tubular configuration by transverse members interconnecting a pair of extruded members by weldments.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

FIG. 1 is an elevational view of a load supporting tower assembled from components including modular units in accordance with the principles of this invention;

FIG. 2 is a fragmentary perspective view of a foundation unit supporting the FIG. 1 tower structure;

FIG. 3 is a perspective view on an enlarged scale of a prefabricated unclimbable modular unit;

FIG. 4 is a perspective view on an enlarged scale of a climbable modular unit shown in FIG. 1;

FIG. 5 is a perspective view of one of the joint members interconnecting some of the modular tower units;

FIG. 6 is a perspective view of a plate usable to interconnect adjacent climbable units, to mount cantilever insulators or for other purposes;

FIG. 7 is a perspective view of a component usable to connect a cross arm to the tower;

FIGS. 8, 9, 10 and 11 are perspective views of kit components usable for various purposes including connecting guy cables to the tower;

FIG. 12 is a view on an enlarged scale taken on FIG. 1 showing details of hardware interconnecting the climbable and unclimbable modules;

FIG. 13 is a cross sectional view taken along the broken line 13--13 on FIG. 12;

FIG. 14 is a cross sectional view on an enlarged scale taken along line 14--14 on FIG. 13;

FIG. 15 is a cross sectional view on an enlarged scale taken along line 15--15 on FIG. 13;

FIG. 16 is a view on an enlarged scale taken along line 16--16 on FIG. 14;

FIG. 17 is a view on an enlarged scale taken along line 17--17 on FIG. 15;

FIG. 18 is a fragmentary elevational view of the upper end of a tower showing one mode of supporting three insulators in suspension from a pair of tubular cross arms;

FIG. 19 is a view similar to FIG. 18 but showing three power line insulators supported cantilever fashion;

FIG. 20 is an elevational view of the upper end of a tower assembly employed as a dead end anchorage for three power conductors;

FIG. 21 is the view of the upper end of a power structure showing a different mode of supporting three insulators cantilever fashion on opposed sides of the tower;

FIG. 22 is a view similar to FIG. 21 but showing a different mode of supporting the insulators cantilever fashion;

FIG. 23 is an elevational view of a pair of the invention towers in side-by-side relation and cooperating to support three insulators from a common cross arm;

FIG. 24 is a cross sectional view on an enlarged scale taken along line 24--24 on FIG. 18;

FIG. 25 is a cross sectional view on an enlarged scale taken along line 25--25 on FIG. 24;

FIG. 26 is a cross sectional view on an enlarged scale taken on a horizontal plane as indicated by the dot and dash line at 26 in FIG. 18;

FIG. 27 is a fragmentary view on an enlarged scale taken along line 27--27 on FIG. 21;

FIG. 28 is a side view on an enlarged scale of the zone indicated by 28 in FIG. 20;

FIG. 29 is a cross sectional view taken along line 29--29 on FIG. 28;

FIGS. 30A and 30B are side sectional and end plan views, respectively, of an angle iron coupling that incorporates shear resistive teeth;

FIGS. 31A and 31B are side sectional and end sectional views, respectively, of a corner member of a modular tower of the invention illustrating meshing shear resistive teeth; and

FIG. 32 is a modification of FIG. 17 showing shear resistive teeth on an angle iron coupling and a corner member of the module.

The annexed drawings show the components constituting the invention kit, selected ones of which can be assembled in the field to provide a variety of supporting structure, illustrative ones of which are shown in FIGS. 1, 18, 19, 20, 21, 22 and 23. Although each of these is shown in use to support power line insulators and conductors, it will be understood that the kit components can be assembled to support load bearing structures for many other purposes.

As shown in FIG. 1, the tower, designated generally 10, includes a tubular foundation module 11, a pair of prefabricated unclimbable modules 12, 12, and a plurality of prefabricated climbable modules 13, 13 rigidly interconnected in axial alignment. A long tubular cross arm 14 traverses the upper end of the upper portion of the tower and supports a pair of insulators 15, 15 in suspension whereas a shorter tubular cross arm 16 extends from one side of the tower tops and supports a third insulator 18.

Modules 11, 12 and 13 are connected together by joints made by abutting the modules end-to-end and securing thereto couplings that overlap portions of the length of the modules adjacent their abutting ends. In the following description, the couplings take three exemplary forms, namely angle irons 22, bridging plates 30, and angle irons 34. The described joint is compact, as distinguished from flanged joints, and can be used to connect power pole units or sections having uniform cross-section, as distinguished from slip joints.

The foundation module 11 comprises a tube 20, the major portion of which is buried in the ground at the installation site. Welded crosswise of the upper end of tube 20 is a plate 21 having upright steel angle irons 22 welded to its corners having bores for fasteners rigidly securable to the lower end of modular unit 12. Modules 11 and 12 abut each other end-to-end. Angle irons 22 overlap a portion of the length of unit 12 adjacent its abutting end and is secured to unit 12 by fasteners not illustrated in the drawings.

Modular unit 12 comprises a plurality of extruded aluminum corner members 25 preferably but not necessarily extending parallel to one another and interconnected by plates 26 welded thereto. Plates 26 are preferably substantially imperforate thereby forming with corner members 25 a closed, i.e. imperforate, outer surface that makes modules 12 unclimbable by unauthorized persons. As is best shown in FIG. 13, corner members 25 are preferably interconnected by internal cross bracing ties 27 extending diagonally of the interior of the modules as is best shown in FIG. 13.

The climbable prefabricated modules 13 shown in FIG. 4 include similar extruded corner members 25 rigidly interconnected in a tubular arrangement by step-forming cross members 28 conveniently spaced to form a ladder usable by service personnel. As illustrated in FIG. 4, the spacing between cross members 28 forms an open, lattice work outer surface that makes units 10 climbable. Although not shown in FIG. 4, it will be understood that modules 13 also preferably include diagonal cross bracing welded to the corner members.

Typically, the prefabricated modules are made in units or sections of convenient length, such as 20 feet, although they may be made in any of various shorter lengths if desired. Normally, a single 20 foot unclimbable section 12 suffices to prevent unauthorized persons from climbing the tower, but if the tower is located closely adjacent building structures a pair of unclimbable modules may be desirable. In this event they are interconnected by four bridging plates 30 by cap screws 31 extending through holes in the plates 30 and in corner members 25 and into the threaded bores of anchor plates 33 held assembled to the interior of corner members 25 as by cap screws 32 in the manner shown in FIG. 14. The threaded bores are provided in anchor plates 33 so the workmen do not have to apply nuts to the fasteners for bridging plates 30. The interconnected modules are abutted end-to-end. Bridging plates 30 overlap portions of the length of the modules adjacent their abutting ends and are secured thereto by caps screws 31.

The climbable modules 13 are rigidly anchored to one another and to the uppermost end of a unclimbable module 12 in the manner best shown in FIGS. 12 and 15 using the angle irons 34 shown in FIG. 5. Since the imperforate panels 26 of a module 12 make it difficult for the workman to apply nuts to the fasteners for the lower ends of angle irons 34, the upper end of the modules 12 are also provided with anchor plates 33 held thereto by cap screws 32 in the manner shown in FIG. 15. However, workmen do have access to the interior of modules 13 and therefore nuts and bolts 35 can be employed.

Modules 12 and 13 are abutted end-to-end. Angle irons 34 overlap portions of the length of modules 12 and 13 adjacent their abutting ends and are secured to the overlapping portions of modules 12 and 13 by cap screws 31 and nuts and bolts 35, respectively.

The kit provided by this invention is useful in providing support towers of a wide range of lengths as, for example, between 25 and 125 feet or more. Towers of any substantial height carry heavy loads and should be rigidly supported in an upright position by guy cables employed in any suitable number and at suitable levels. One typical arrangement is shown in FIG. 1 wherein the guy cables 37 are connected to the opposite ends of an anchor plate 38 extending crosswise of the tower and made as shown in FIG. 9. This strip is secured to the tower as by a pair of the angle members 39 shown in FIG. 10. The horizontal leg 40 of this member is boltable to a respective one of the holes 41 spaced to either side of the midlength of strip 38. The vertical legs of member 39 are of course securable by bolts to the tower corner members 25. A alternate guy cable anchor strip 42 is shown in FIG. 8 and is useful where a horizontal tie cable is to be attached to one end of the strip and a guy cable to the other end. For example, see such a strip mounted crosswise of the top of the tower shown in FIG. 20 and used as an anchorage for the end of a neutral or grounding conductor 44. Another strip 42 is also there shown for use as the anchorage for the dead end insulator 43.

Reference will now be had to FIGS. 18, 24, 25 and 23, showing different modes of using tubular cross arms to support suspended insulators. FIG. 18 shows cross arms of two different lengths, the shorter 50 arm being used to support a single insulator from its outer end and the longer arm 51 projecting equal distances outwardly from the opposite sides of the tower and supporting a pair of insulators 18, 18. As shown, the cross arms are tubular and rectangular in cross section and project through the modules 13 to which they are anchored by the U-shaped brackets 53 best shown in FIG. 7. The legs of these brackets are rigidly secured to a pair of the corner members 25. Reinforcing bracing 55 preferably connects the outer ends of the cross arms to an overlying portion of the tower by means of the brackets 39 shown in FIG. 10.

If cantilever type insulators 58 are to be employed their base plates are anchorable to plates 59 best shown in FIG. 6 having their opposite lateral edges bolted to corner members 25 of a tower section 13 such as in the manner illustrated in FIGS. 19 and 21. Cantilever insulators 58 can be mounted on the same side of the tower as shown in FIG. 19, or on the opposite sides as shown in FIGS. 21 and 22. In some cases, it is desirable to provide additional support for the outer end of a cantilever insulator, such as by an inclined insulator 60 connected to the tower in the manner clearly shown in FIG. 22.

In order to prevent the couplings from slipping and tilting the tower form a straight vertical orientation due to shear force exerted by loads on the tower, meshing teeth are formed on the couplings and the overlapping surfaces of the interconnected modules. These teeth provide a metal-to-metal bearing contact that resists slipping. In FIGS. 30A and 30B a modified angle iron 34' has a plurality of teeth-forming transverse protrusions 100 spaced along the length of its interior apex. Angle iron 34' has a plurality of bolt holes 102 spaced along the length of one leg and a plurality of bolt holes 104 spaced along the length of the other leg. In FIGS. 31A and 31B a modified corner member 25' has a plurality of teeth forming transverse grooves 106 spaced along the length of its exterior apex. Corner member 25' has a plurality of bolt holes 108 spaced along the length of one leg and a plurality of bolt holes 110 spaced along the length of the other leg. Protrusions 100 and grooves 106 are distributed so that they fit together, i.e. the teeth formed thereby mesh. Likewise holes 102 and 104 are in registration with holes 108 and 110, respectively, when the ends of the modules abut each other and angle iron 34' is in place. As depicted in FIG. 31B, grooves 106 are rounded to relieve stress at the apex of corner member 25'. In order to distribute the stress evenly along the length of angle iron 34' and corner members 25', protrusions 100 and grooves 106 are more closely spaced together near the abutting ends of the modules as illustrated in FIG. 30A. Holes 102, 104, 108 and 110 are staggered to increase the strength of the joint.

From the foregoing it is apparent that this invention provides a highly versatile kit of simple, rugged, easily manufactured long life components selectively usable in a variety of manners to provide a rigid heavy load-supporting structure not only for power lines but for many other applications. The main tower units are preassembled at the factory and readily transported to the erection site by light weight cargo carriers or by helicopter. The modules are readily assembled in end-to-end relation by simple equipment or lowered into field assembly position by helicopter. The cross arm units are simple and easily secured crosswise of the tower as is guy cabling.

While the particular lightweight power line tower kit herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.