Abstract:
A telescoping tower includes a plurality of nested tower sections extendable in a telescoping direction, each of the plurality of nested tower sections having a plurality of legs that define respective heights of the plurality of nested tower sections in the telescoping direction, each of the plurality of legs slidably engaging at least one leg of at least one adjacent one of the plurality of nested tower sections along an overlap in the respective heights thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Non-provisional patent application Ser. No. 14/137,936, filed on Dec. 20, 2013, and claims the benefit of U.S. Provisional Patent Application Ser. No. 61/740,164 filed on Dec. 20, 2012, the contents of which applications are herein incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to telescoping towers, and more particularly, to legs usable in connection therewith. 
     BACKGROUND OF THE INVENTION 
     Traditional telescopic, crank-up, or lattice towers, as they may be referred to in the industry, consist of several tower sections, varying in size in order to slide in and out of one another and achieve the maximum elevation. These sections are connected together through a series of cables, pulleys and a winch responsible for raising and lowering sections individually or simultaneously. The process that combines cables, pulleys and a winch is referred to as “rigging” in the industry. 
     A shared problem in the telescopic, crank-up, and lattice tower industry arises from the spacing between the varying sized sections. This spacing or gap is typically measured as the distance between one leg of a section and the leg of the adjacent section. Known in the industry as “play between sections,” the gap can be as small as ⅛ inch or as much as ¼ inch. While “section play” is required to allow the sections to raise and lower, it allows lateral and/or angular motion that applies undesired torque and adversely affects the overall strength and stability of telescopic, crank-up, or lattice towers with two or more sections. The effect is amplified with every additional section. In windy conditions, the play between sections creates pressure points at several different locations along the tower legs, potentially weakening these areas and increasing the probability of failure. 
     Some companies in the industry try to eliminate the play between sections by adding wheels, or rollers to the top of the outer section&#39;s legs, top and bottom of every inner section&#39;s legs in between and finally the lower legs of the inner most section. Unfortunately, this creates major stress on the points of contact where the wheels or rollers are located. In addition, it reduces the lifespan of the legs, pulleys and even the tower legs by creating wear points on the leg surfaces. 
     An improvement on this general concept involves the use of a slide bar mechanism. At the point where the slide bars meet play between sections is eliminated by the slide bars pressing up against one another. An example of this mechanism can be seen in U.S. Pat. No. 8,046,970, the contents of which are incorporated by reference herein, in their entirety. Nonetheless, further improvements are possible. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide an improved telescoping tower and leg therefor. According to an embodiment of the present invention, a telescoping tower includes a plurality of nested tower sections extendable in a telescoping direction, each of the plurality of nested tower sections having a plurality of legs that define respective heights of the plurality of nested tower sections in the telescoping direction, each of the plurality of legs slidably engaging at least one leg of at least one adjacent one of the plurality of nested tower sections along an overlap in the respective heights thereof. 
     According to an aspect of the present invention, a first tower section has a first leg extending in the telescoping direction, the first leg including first leg female and male sides extending in parallel in the telescoping direction and connected therealong by a first leg web. A second tower section has a second leg extending in the telescoping direction, the second leg including a second leg female side extending in the telescoping direction, a second leg slot extending in the telescoping direction being defined in the second leg female side. The first leg male side is slidably retained in the second leg female side with the first leg web extending through the second leg slot to support telescopic movement of the first tower section relative to the second tower section in the telescoping direction. 
     These and other objects, aspects and advantages of the present invention will be better appreciated in view of the drawings and following detailed description of preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a telescoping tower, according to an embodiment of the present invention, in a fully extended configuration; 
         FIG. 2  is a side view of the telescoping tower of  FIG. 1 , in a fully retracted position; 
         FIG. 3  is an end view of an exemplary leg of the telescoping tower of  FIG. 1 ; 
         FIG. 4  is a partial perspective view of the leg of  FIG. 3 ; 
         FIG. 5  is a partial perspective view of the leg of  FIG. 3 , with linear slide bearings mounted thereon; 
         FIG. 6  is a partial perspective view of a plurality of slidably connected legs, according to another embodiment of the present invention; 
         FIG. 7  is a partial end view of a telescoping tower, including the legs of  FIG. 6 ; and 
         FIGS. 8 and 9  and are schematic end views of telescoping towers, according to further embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 and 2 , according to an embodiment of the present invention, a telescoping tower  10  includes a plurality of nested tower sections  12 - 18  that are extendable in a telescoping direction  22 . The sections  12 - 18  are extended in  FIG. 1  and retracted in  FIG. 2 . Each of the sections  12 - 18  includes a plurality of legs  30  extending, and generally defining the height of their respective sections  12 - 18 , in the telescoping general. Each of the legs  30  slidably engages at least one adjacent leg  30  of an adjacent one of the sections  12 - 18 . In the case of the outer- and innermost nested sections  12 ,  18 , the legs  30  each slidably engage one adjacent leg  30 , whereas each leg of the intermediate sections  14 ,  16  will slidably engage two adjacent legs  30 . 
     The slidable engagement between adjacent legs  30  is advantageously substantially continuous over all the overlap  32  in the heights of adjacent sections. As is explained in greater detail herein, the design of the legs  30  allows this continuous engagement to be maintained in both the extended and retracted positions of the tower  10 , as well as throughout the transition therebetween. As a result, play between sections  12 - 18  is significantly reduced, enhancing the effective structural integrity of the telescoping tower  10 . 
     Notably, the tower  10  is not limited to any particular rigging or other mechanism for expanding and/or retracting the sections  12 - 18 , including both automated and manually actuated mechanisms. Additionally, the tower  10  could be transported to and anchored at a prospective site of use according to a variety of means. For example, the tower could be mounted horizontally to a trailer, and erected and expanded on the trailer when in use. Alternately, the tower could be removed from a trailer or other transport mechanism, and anchored to the ground or other mounting platform, in situ. Additionally, the expanded tower could be guyed or unguyed. 
     Referring to  FIGS. 3-5 , an exemplary leg  30  includes a female side  34  and male side  36 , which extend in parallel in the telescoping direction  22  and are connected by a web  40 . Both the female and male side  34 ,  36  preferably extend for the entire length of the leg  30 . Advantageously, the male side  36  is at least long enough to extend throughout the entire overlap  32  between adjacent sections when the tower  10  is fully extended in the telescoping direction  22 . The web  40  is preferably continuous between the female and male sides  34 ,  36  in the telescoping direction, but could alternately be intermittent. 
     The female side  34  has a hollow interior  42  and defines a leg slot  46 . Preferably, the leg slot  46  is slightly wider than the web  40  and the hollow interior  42  is dimensioned slightly larger than the male side  36 , such that an identical male side could be slidably accommodated within the hollow interior  42  with an identical web extending through the leg slot  46 . Additionally, the leg slot  46  is substantially narrower than the male side  36 , such that the identical male side would be retained within the female side  34  and only capable of sliding movement in the telescoping direction  22 . Also, the web  40  meets the female side  34  generally opposite the leg slot  46 , such that the webs of adjacent legs would be aligned with one another. 
     Connection tabs  44  are formed on the female side  34 , which facilitate the attachment of interconnection members thereto for interconnecting the legs of each tower sections  12 - 18 . Exemplary interconnection members include rungs  48  and diagonals  50  (see  FIG. 1 ). The connection tabs  44  are preferably located equidistant from opposite sides of the web  40 , such that the web  40  bisects the apex of its respective corner of a tower section. For instance, in the case of a triangular tower section, the connection tabs  44  would be offset 30 degrees on either side of the web  40 ; in a square tower section, the connection tabs would be offset 45 degrees on either side of the web  40 . 
     To facilitate sliding motion between adjacent legs  30 , slide bearings  52  can be included so as to be between the male side  36  and the female side of an adjacent leg in which it is received. Preferably, linear slide bearings are used, and phenolic linear slide bearings are believed to be particularly advantageous. Slide bearing mounting rails  54  are located on the outer surface of the male side  36 , with the mounting rails  54  extending in the telescoping direction  22 , to receive the slide bearings  52 . Alternately, the mounting rails  54  could be formed on the inner surface of the female side  34 . 
     In the depicted embodiment, the female and male sides  34 ,  36  have complementary generally circular sections when viewed in the telescoping direction (as in  FIG. 3 ). Alternately, other complementary shapes could be used, such a triangles or squares. Advantageously, the female and male sides  34 ,  36  and the web  40 , as well as the connection tabs  44  and mounting rails  54 , are formed as a single, unitary structure; for example, with the leg  30  being extruded. A strong but relatively lightweight metal, such as aluminum, is preferred, but other metals and other manufacturing processes, could be used. For example, legs could be formed from carbon fiber, rigid plastics material, or composite materials. Legs could be cast, machined and/or molded. For weight reduction, the male side  36  can advantageously be formed with a hollow interior, also. 
     Referring to  FIGS. 6 and 7 , a plurality of interconnected legs  30 A- 30 E are shown. The legs  30 A- 30 E are shown forming one corner of adjacent tower  10 A sections, with rungs  40  extending therefrom attached to connection tabs  44 . The intermediate legs  30 B- 30 D are substantially identical, whereas the outermost leg  30 A lacks a leg slot, as it does not need to receive the male side of an adjacent leg. Similarly, the innermost leg  30 E lacks a male side, as there is no female side of an adjacent leg for it to be received in. Alternately, the outer- and/or innermost legs could be made identical with the intermediate legs. 
     Each leg  30 A- 30 E slidably engages at least one adjacent leg, with the intermediate legs  30 B- 30 D (shown particularly in  FIG. 6 ), each slidably engage two adjacent legs. The female sides of more inwardly legs  30 B- 30 E slidably retain therein the male sides of more outwardly legs  30 A- 30 D, with the webs of the more outwardly legs extending through the leg slots of the more inwardly legs. Secure and stable extension and retraction in the telescoping direction  22  is thereby achieved, with minimal play between sections possible due the large contact area between legs throughout their overlapping heights. The linear slide bearings  52  between male and female sides of adjacent sections further facilitates sliding movement. 
     In addition to differently configured inner- and/or outermost legs, the present invention could be practiced with legs with changing dimensions. By way of illustration, each female section of a leg of the tower  10 A is approximately the same diameter, as is each male section. However, the legs could, for example, get gradually smaller from outermost to innermost, as might be desired to reduce the weight of the top of the tower when extended. In such a tower, the outermost leg could have a male side somewhat smaller than the interior of its female side, so as to be slidably retained in a somewhat smaller female side of the adjacent leg. Thus, the sliding relationship and mutual engagement between legs would be retained, but the innermost legs would be smaller and lighter than the outermost legs. 
     In most telescoping towers, the legs will be interconnected to form a closed geometric figure. For example, a four legged tower  110  forms a square (as in  FIG. 8 ) or a three legged tower  210  forms a triangle (as in  FIG. 9 ). However, towers consisting of any number of legs and forming any open or closed geometric figure could be advantageously made using the legs of the present invention. Additionally, a telescoping tower could be made of as few as two sections, up to as many as were needed and feasible for a given application. 
     In general, the foregoing description is provided for exemplary and illustrative purposes; the present invention is not necessarily limited thereto. Rather, those skilled in the art will appreciate that additional modifications, as well as adaptations for particular circumstances, will fall within the scope of the invention as herein shown and described and the claims appended hereto.