Abstract:
A support tower for large structures such as wind turbines generators, microwave structures, high voltage transmission lines or the like, constructed of telescopic sections with the lowermost section having an edge portion pivotally connected to a foundation to enable the tower sections to be transported to the site of installation. The tower sections are assembled at the installation site in a nested relationship, each within the adjacent lower tower section. The large load is mounted on the upper end of the uppermost tower section and the nested tower sections are then tilted upwardly to a vertical position. After the tower is tilted to its vertical position and securely connected to the foundation, the telescopic tower sections are vertically extended to position the load in a vertically elevated position.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention generally relates to tall support towers f or large structures, such as wind turbine generators, microwave antennas or the like, and, more specifically, to tall support towers which are constructed of multiple telescopic sections that telescopically extend vertically to the tower&#39;s full height and/or to tall support towers which are assembled at the site of installation in a generally horizontal position, and then tilted upwardly to a vertical position. The present invention incorporates both features into unique support tower structures.  
           [0003]    2. Description of the Prior Art  
           [0004]    Wind-powered windmills and turbines have been in use for many years for producing power for many purposes. Wind power to drive wind turbine generators to generate electrical energy have been used as an alternative energy source for many years, and the development of such uses of wind power is ongoing as exemplified by the following U.S. patents.  
                                                             11,181   3,495,370   4,323,331             446,744   3,715,852   4,590,718           2,213,870   4,231,200   4,903,442           2,267,705                      
 
           [0005]    Initial development of wind turbine generators to produce electrical energy involved relatively small turbines and generators having a capacity of approximately 50 to 65 kilowatts, which were supported by small towers of approximately 50 to 75 feet in height. Towers of this height were typically fabricated from steel truss members of rectangular plan configuration and of lightweight construction. The lightweight construction enabled the towers to be initially positioned generally horizontally with the lower end pivotally connected to a foundation and the wind turbine and generator mounted at the upper end. The tower was then tilted upwardly to a vertical position by a cable and winch assembly or other power source to pull the tower to a vertical position on the foundation from the generally horizontal position. This tilting of the tower provided a relatively inexpensive installation that could be quickly and efficiently completed in a short time and required the use of only small and highly mobile erection equipment. A problem existed, however, in that as the tower was tilted into vertical position, the feet of the tower conflicted with anchor bolts that protruded from the foundation which would prevent the tower from setting flat on the foundation. This was resolved by bolting multiple steel adapter structures to the anchor bolts with the flat upper surface of each adapter receiving one of the feet of the tower. The tower feet were then bolted to the top of the adapters through matching bolt holes in the feet and top surface of the adapter.  
           [0006]    More recent wind power generation included the development of larger and more efficient and cost-effective turbines capable of driving larger generators, having capacities up to approximately 750 kilowatts. The larger turbines and higher capacity generators required that taller support towers be provided in order to maximize the use of winds existing at higher elevations which have higher average speeds and smoother air flow characteristics than winds closer to the ground. In order to erect the larger towers to support the wind turbine generators at the higher elevations needed to maximize power production, heavy lift cranes with a lift capacity of up to 230 tons are used. The taller towers, either steel truss or tubular cross-sectional configuration are erected in sections by the crane and assembled in the vertical position. Each section of the tower is rigidly affixed to the adjacent tower sections by means of bolted connections. In the case of tubular cross-section towers the bolted connections are created through use of matching inwardly oriented flanges at each joint which contained matching boltholes to receive the bolts. The wind turbine generators are then mounted on top of the vertically oriented tower. This procedure is effective for towers up to approximately 180 feet in height with turbine and generator assemblies weighing up to approximately 60,000 pounds.  
           [0007]    However, as the tower height increased along with the generating capacity and the weight of the wind turbine generator, the costs of installation increased materially. The transportation costs to move a heavy lift crane to a site of installation and then remove it from the site of installation, as well as the rental cost for a heavy lift crane, can be extremely high. A typical heavy lift crane with a lifting capacity of approximately 230 tons is barely capable of installing a 750 kilowatt wind turbine generator on a tower that is about 200 feet tall. Extra-heavy lift cranes with even higher costs are required for taller towers or heavier generators. Use of the extra-heavy lift cranes increases costs dramatically due to the very high rental and transportation costs of these larger units. Additional costs include the requirement for multiple large trucks and trailers for moving the extra-heavy lift crane to and from the job site, increased risk of serious accidents while traveling during movement of the crane to and from the job site, as well as at the job site, and increased wear and tear on public highways and plant site roads.  
           [0008]    The massive size of extra-heavy lift cranes and their limited mobility require that work sites be well prepared to assure stability during the erection process. An extra-heavy lift crane work site requires extensive preparation of road bases with minimal tolerance for allowable slope of the road or for side to side pitch and crane working pads which require the use of heavy temporary matting beneath the cranes. Also, once on a job site, the cranes need to be moved frequently from one wind turbine foundation to another which further adds to high maintenance costs on the cranes and roads and expensive time-consuming moving procedures. This is especially problematic at preferred and available job sites which are usually near the top of hills, ridges or mountains which require erection equipment to be highly mobile in order to minimize erection time and cost. Use of the extra-heavy lift cranes means that many of the best sites cannot be used due to the excessive cost of road and pad construction needed for the larger cranes.  
           [0009]    Heavy lift cranes are typically near their maximum safe working ranges when erecting wind turbine generators of 600-750 kilowatt capacity on towers as high as 200 feet. This condition makes it necessary to suspend erection work during winds in excess of 20 to 25 miles-per-hour in order to avoid excessive wind loads on the long crane booms and on the structure being lifted that exceed the safe working loads of the crane. In job sites where such towers are erected, it is not unusual for erection work to be delayed for several days during a windy season and work is frequently delayed due to inclement weather such as rain, ice accumulation or snow. Other constraints associated with heavy and extra-heavy lift crane use include requirements for good visibility so that the operator can see hand signals given by a loadmaster, limited availability of extra-heavy lift cranes during periods of high construction activity, limited availability of extra-heavy lift cranes capable of erecting wind turbine generators having a capacity greater than 750 kilowatts and the time and large number of equipment components necessary to move larger capacity lift cranes to and from the site of tower erection.  
           [0010]    The cost and availability of extra-heavy lift cranes has become a serious limiting factor to further economic development of wind energy especially in view of the ongoing development of wind turbine generators having a capacity of up to approximately 2,500 kilowatts. Such generators will require towers as tall as 350 feet in height with turbine generator combinations weighing in excess of 150,000 pounds. Accordingly, the use of increasingly heavier wind turbine generators mounted on ever taller towers has reached a point where the cost of construction has become a significant constraint to further development. Likewise, the limited availability of extra-heavy lift cranes capable of erecting such taller towers and installing heavier wind turbine generators at the upper end thereof have introduced additional serious constraints on the development of wind-powered electrical energy generation.  
           [0011]    While the above-identified patents and prior developments in the construction of supporting towers for wind-powered energy include towers which are pivotally supported for tilt-up erection, sectional tower constructions and telescopic tower constructions, the prior art does not disclose a tower assembly incorporating these features which can be constructed to a height and weight capacity necessary to support the larger wind turbine generators without the use of extra-heavy lift cranes.  
         SUMMARY OF THE INVENTION  
         [0012]    In order to overcome the constraints described above in connection with tall towers for large and heavy wind turbine generators, the present invention provides a tall tower capable of supporting a heavy wind turbine generator that starts out as multiple independent tubular tower sections which are nested inside each other while in a generally horizontal position. The number of tower sections is dependent on the desired tower height and configuration and may require two, three or four, or even more, tower sections. The nested sections are appropriately interconnected so as to be internally spaced one from another while oriented in a generally horizontal position at the job site prior to erection. The outermost tower section has a lower edge pivotally connected to the tower supporting foundation by means of a removable hinge structure.  
           [0013]    A unique cable, pulley, winch and gin pole structure is then used to tilt the generally horizontal nested sections to an upright vertical position. The wind turbine generator may be mounted on the top end of the innermost tower section either before or after the nested tower sections are tilted to their upright vertical position. Once tilted into their vertical position, the nested tower sections are secured onto the foundation by a flange at the lower end of the outer tower section which is secured to the foundation by a plurality of bolt arrangements. The hinge mechanism is then removed for use on subsequent tower installations. The inner tower section or sections and the wind turbine generator are then telescopically raised to the final elevated position by a unique elevating and guiding mechanism that extends the inner tower section or sections to the maximum vertical height of the tower. Once extended to full height, the tower sections are fastened together to form a rigid structure by means of matching but oppositely oriented flanges with matching boltholes. By combining a tilting and telescoping tower assembly, the necessity for using extra-heavy lift cranes at the job site can be eliminated. Additionally, the towers can be telescopically lowered for maintenance access purposes, eliminating the need for extra-heavy lift cranes during maintenance.  
           [0014]    The unique portable gin pole mechanism of the present invention is preferably a lattice frame structure having its lower end pivotally connected to the tower foundation in spaced opposed relation to the pivotal connection between the outer tower section and the foundation. The gin pole is attached to the foundation by pivotal connections while in a generally horizontal position and then raised from a generally horizontal position and oriented in a position angled outwardly in relation to the final vertical position of the nested tower sections when they are vertically positioned. An inexpensive light-weight crane assists in initially raising the outer end of the gin pole, from its beginning horizontal position and then the weight of the at rest tower and wind turbine generator is used as a counterweight in raising the gin pole to its upright position by operating the winch and tightening the cable that is associated with the winch. The upper end of the gin pole and the upper end of the outer tower section tilt the gin pole structure upwardly about the pivotal connections between the base of the gin pole and the foundation.  
           [0015]    The gin pole is then anchored in its upwardly angled position. The nested tower sections are then tilted upwardly to their vertical position by a winch mounted on the foundation with a cable and pulley arrangement associated with the upper end of the gin pole and the upper end of the outer tower section. The nested tower sections are thus tilted upwardly about the pivotal connection between the outer tower section and the foundation.  
           [0016]    Recessed anchor bolts consisting of high strength threaded rods topped with threaded couplers are embedded in the concrete foundation flush with the top of the foundation. The couplers receive high strength bolts that rigidly affix the base or anchor plate of the vertically oriented outer tower section to the foundation. Use of the threaded couplers flush with the foundation top surface allows the nested tower sections to be tilted into place without conflicting with embedded anchor bolts that otherwise extend above the surface of the concrete foundation.  
           [0017]    After the nested tower sections are positioned in their vertical position and the outer tower section is rigidly bolted to the foundation, the lifting mechanisms in the tower are activated to extend the nested tower sections. In a preferred embodiment, the lifting mechanism between the outermost tower section and the adjacent or second tower section nested inside the outermost section is a jacking mechanism, and the lifting mechanism between the second tower section and additional tower sections, such as a third and perhaps fourth tower section, is a cable and pulley mechanism. The cable and pulley mechanism interconnects each of the innermost upper tower sections preferably in a manner such that all of the innermost upper nested tower sections automatically extend when the jacking mechanism extends the second tower section from its nested relationship within the outer lowermost tower section.  
           [0018]    Alternatively, additional jacking mechanisms in lieu of the cable and pulley mechanism may be positioned internally of the second tower section to engage and lift the lower end of the third tower section, and similarly for additional tower sections, if used. The multiple jacking mechanisms can be operated simultaneously or independently through the use of manual controls or a computerized control system, giving full control of the telescoping operation.  
           [0019]    The lifting mechanisms further include a guide system to guide the tower sections as they telescope vertically with respect to each other. A preferred guide system includes inner and outer rollers interacting between adjacent tower sections. The guide system associated with the cable and pulley mechanism acts in a manner to bias the rollers into engagement with internal and external surfaces of the tower sections as they are being extended. This biasing engagement of the rollers prevents relative lateral movement between tower sections so that adjacent tower sections do not come into contact with each other, which would cause damage to hardware installed on the inner surfaces of each tower section.  
           [0020]    The jacking mechanism is positioned internally of the outermost lower tower section and includes crawler jacks positioned on vertical, parallel jackrods extending between the upper and lower ends of the outermost lower tower section. The crawler jacks are positioned below the second tower section and engage the lower end of the second tower section to lift it upward, or lower it downward. The inner guide rollers associated with the jacking mechanism are affixed to the lower structure of the second tower section and engage the internal surfaces of the lowermost tower section as the second section is being extended. The outer guide rollers are affixed to the upper flange of the lowermost tower section and engage the external surface of the second tower section. These guide rollers also prevent lateral movement of the second tower section so that the first and second tower sections do not come into contact with each other, which would cause damage to hardware installed on the inner surface of the first tower section.  
           [0021]    Also in accordance with the present invention, the floor of the foundation is preferably recessed below the base of the support tower for mounting electronic controls and switchgear required for operation of the wind turbine generator. Recessing the floor in this manner allows the controls and switchgear to be mounted on the foundation prior to assembly and erection of the tower sections and provides sufficient clearance between the bottom tower section and the switchgear when the tower is tilted into the vertical position such that the switchgear does not conflict with erecting the tower.  
           [0022]    It is therefore an object of the present invention to provide a tilt-up telescopically sectional tower for supporting a large load at the tower top such as a wind turbine generator, microwave communication equipment, high voltage electrical transmission lines and the like.  
           [0023]    Another object of the present invention is to provide a support tower for a wind turbine generator in which the tower includes a plurality of telescopically associated tower sections that are horizontally supported with an outer lowermost tower section hingedly connected to a supporting foundation. The nested tower sections are tilted upwardly to a vertical position and securely anchored to the foundation. The tower sections are then telescopically extended vertically to elevate the wind turbine generator to a fully extended position.  
           [0024]    Still another object of the present invention is to provide a support tower including a plurality of nested telescoped tower sections of decreasing cross-sectional area from a lower tower section to an upper tower section. The tower sections are horizontally positioned and then tilted to a vertical position and securely anchored to the foundation. The tower load, such as a wind turbine generator or the like, is mounted on the upper end of the uppermost tower section either before or after the nested tower sections are tilted into the vertical position, after which the tower sections are extended to their full vertical height to position the tower load in an elevated position.  
           [0025]    A further object of the present invention is to provide a support tower in accordance with the preceding objects in which the erection process can be safely and quickly performed by a small crew of personnel while maintaining complete stability of the tower sections during erection with the elevating process being reversible in the event it is necessary to lower the load supported at the upper end of the tower for maintenance or replacement purposes.  
           [0026]    Still another object of the present invention is to provide a support tower for supporting heavy structures at a high elevation in accordance with the preceding objects in which the cost of erection is minimized by utilizing equipment that can be easily transported to and from the site of erection, requiring the use of a minimum number of personnel during the erection procedure, enabling the erection process to be completed in a safe and efficient manner in adverse weather and lighting conditions and enabling heavy structures to be supported from the tower by tilting the tower from a horizontal position to a vertical position and then extending telescopic tower sections to a full vertical height of the tower.  
           [0027]    Yet another object of this invention to be specifically enumerated herein is to provide a tilt-up and telescopic tower for wind turbines and other structures in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and easy to use so as to provide a support tower that will be economically feasible, long lasting and relatively trouble free in operation.  
           [0028]    These together with other objects and advantages that will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    [0029]FIG. 1 is a schematic side elevational view illustrating an initial step in delivering a lowermost tower section to an installation site having a preinstalled foundation. A removable hinge plate is affixed to the bottom surface of the tower section bottom flange for subsequent pivotal connection with a removable pin mechanism attached to the foundation.  
         [0030]    [0030]FIG. 2 is a schematic end elevational view illustrating one manner of lifting the lowermost section of the tower for pivotal connection with the foundation.  
         [0031]    [0031]FIG. 3 is a schematic side elevational view illustrating a first step in the assembly of a second tower section in internal nested relation to the lowermost outer tower section which is supported horizontally by blocks at the upper end and by the pivotal connection to the foundation at the lower end.  
         [0032]    [0032]FIG. 3A is a detail of the pivotal connection showing schematic side and end views of the assembled hinge, foundation and bottom flange of the lowermost tower section.  
         [0033]    [0033]FIG. 4 is a schematic side elevational view similar to FIG. 3 illustrating a second step in the assembly of the second tower section in internal nested relation to the lowermost outer tower section.  
         [0034]    [0034]FIG. 5 is a schematic side sectional view similar to FIGS. 3 and 4 illustrating the final step in the assembly of the second tower section in internal nested relation to the lowermost outer tower section.  
         [0035]    [0035]FIG. 6 is a schematic side elevational view illustrating the internal nested relation of a third tower section within the second tower section and the lowermost tower section.  
         [0036]    [0036]FIG. 7 is a schematic cross sectional view of the second tower section and lowermost outer tower section illustrating the relationship of the removable roller assembly used during nesting of adjacent tower sections.  
         [0037]    [0037]FIG. 8 is a schematic side elevational view illustrating the nested tower sections with a wind turbine generator mounted to the uppermost end of the tower, associated with a gin pole of the present invention and illustrating a lightweight crane lifting the outer end of the gin pole from a horizontal position toward an upwardly angled position.  
         [0038]    [0038]FIG. 9 is a schematic side elevational view illustrating the at rest weight of the horizontally disposed nested tower sections and wind turbine generator being used to pivot the gin pole towards its final position.  
         [0039]    [0039]FIG. 10 is a schematic side elevational view illustrating the gin pole in its anchored final operating position and the use of a lightweight crane to initially assist in lifting the nested tower section and affixed wind turbine generator from a horizontal position towards a vertical position.  
         [0040]    [0040]FIG. 11 is a schematic side elevational view similar to FIG. 10 with the gin pole tilting the nested tower sections and wind turbine generator towards a final vertical position.  
         [0041]    [0041]FIG. 12 is a schematic side elevational view similar to FIG. 11 with the nested tower sections and wind turbine generator tilted to a final vertical position.  
         [0042]    [0042]FIG. 13 is a schematic rear elevational view of the gin pole in its final operating position and its association with the nested tower sections when in a horizontal position.  
         [0043]    [0043]FIG. 14 is a schematic sectional elevational view illustrating the association of first, second and third telescopic tower sections in a partially extended position and showing the lifting mechanisms by which they are extended.  
         [0044]    [0044]FIG. 15 is a schematic sectional detail view illustrating the upper guide for the cable and pulley mechanism to maintain proper spacing between the second and third tower sections during their telescopic movement.  
         [0045]    [0045]FIG. 16 is an additional schematic sectional detail view illustrating the lower guide for the cable and pulley mechanism to maintain proper alignment and internal spacing between the second and third tower sections during extension.  
         [0046]    [0046]FIG. 17 is a schematic sectional detail view of a spring compensator incorporated into the cables of the cable and pulley mechanism for extending the tower sections.  
         [0047]    [0047]FIG. 18 is a schematic side elevational view of a support tower of the present invention and a supported wind turbine generator in their final position.  
         [0048]    [0048]FIG. 19 is a schematic sectional view of a bolted flange joint between the first and second tower sections in their extended position and illustrating the matching but oppositely oriented flanges of the two tower sections that make the telescoping operation feasible, and the bottom skirt and maintenance platform that are attached to the bottom of each upper tower section.  
         [0049]    [0049]FIG. 20 is a schematic sectional view illustrating a support tower of the present invention having three nested tower sections with a segmented ladder structure and a recessed foundation floor.  
         [0050]    [0050]FIG. 20A is a schematic sectional plan detail view of the tower structure of FIG. 20 illustrating the ladder sections for the two lower tower sections nested within the fully installed ladder for the upper tower section at the time the upper tower section is delivered to the site.  
         [0051]    FIGS.  21 - 23  are schematic elevational views of an alternative embodiment illustrating a winch, pulley and cable mechanism for extending the tower sections in lieu of the jacking mechanism illustrated in FIG. 14.  
         [0052]    FIGS.  24 - 27  are schematic elevational views illustrating the mechanism and procedure for extending the nested ladder sections in the upper tower section of the present invention to their final position in the lower tower section.  
         [0053]    [0053]FIG. 28 is a schematic sectional view illustrating the top end of the lowermost outer tower section and the bottom end of a raised inner tower section therein with the lower guide roller mechanism mounted on the outer periphery of the base of the inner tower section engaging the internal surface of the outer tower section and the upper guide roller mechanism mounted on the top flange of the outer tower section engaging the external surface of the inner tower section. Also illustrated are the crawler jacks mounted on the jack rods and contacting a lift structure fastened to the lower edge of the maintenance skirt and platform on the bottom of the inner tower section.  
         [0054]    [0054]FIG. 29 is a schematic detail view illustrating the threaded couplers embedded in the upper surface of the concrete foundation receiving bolts for securing the tower base flange in order to successfully tilt the tower into vertical position. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0055]    Although a preferred embodiment and an alternative lift component of the invention are explained in detail, it is to be understood that the embodiment and alternative are given by way of illustration only. It is not intended that the invention be limited in its scope to the details or sequence of construction and arrangement of components set forth in the following description or illustrated in the drawings. Also, in describing the preferred embodiment, specific terminology will be utilized for the sake of clarity. It is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.  
         [0056]    [0056]FIG. 18 illustrates the assembled support tower, generally designated by reference numeral  20 , in its final vertical position. The illustrated tower consists of three telescoping sections  30 ,  44  and  80 . A wind turbine generator  24  is mounted on the upper end of the innermost section  80  atop the tower  20 .  
         [0057]    FIGS.  1 - 7  illustrate the steps and structure of the tower sections as they are being positioned in nested horizontal position. The lower end of the lowermost outer tower section  30  is connected to a preinstalled foundation  26  by a unique removable split hinge connection  28 , illustrated in FIGS. 3 and 3A. The split hinge connection  28  consists of a hinge plate  36  attached to the bottom surface of the flange  34  of the tower section  30  and a pin mechanism  38  attached to the foundation  26 . The split hinge connection  28  permits the tower  20  to be pivoted from a horizontal position to a vertical position after the tower sections  30 ,  44  and  80  have been telescopically nested while in horizontal position.  
         [0058]    In assembling the tower sections, the lowermost tower section  30  is transported to a position adjacent the foundation  26  by a suitable tractor trailer unit  32 , as illustrated in FIG. 1. The lower end of the lowermost section  30  of the tower includes a base or anchor flange  34  to which a removable reusable hinge plate  36  is affixed to the bottom surface thereof for connection with a removable reusable pin mechanism  38  affixed adjacent the upper end edge of the foundation  26 .  
         [0059]    The lowermost tower section  30  is unloaded from the transport vehicle  32 , as by a lightweight crane  40  such as shown in FIG. 2, which lifts and positions the lowermost section  30  to enable pivotal connection of the components  36  and  38  of hinge  28 , as illustrated in FIGS. 3 and 3A. The connection of hinge  28  thus pivotally connects the flange  34  on lower tower section  30  to the foundation  26  for pivotal movement about a horizontal axis.  
         [0060]    After the lowermost tower section  30  is connected to the foundation  26  through the removable hinge connection  28 , tower section  30  is supported in a generally horizontal position by a support structure  42  which may be in the form of support blocks or the like, at the end thereof remote from the pivotal connection with the foundation. Then the second tower section  44 , after transport to the job site, is lifted as by slings  48  connected to a lightweight crane (not shown in FIG. 3). The second tower section  44  is inserted longitudinally into nesting relationship internally of the lower tower section  30 , as indicated by directional arrow  50  in FIG. 3. The tower section  44  is temporarily provided with rollers  52  attached to the outer side of the flange  100  at the upper end of tower section  44 , as illustrated in FIGS. 3, 4 and  7 . The rollers  52  maintain a spaced relation between the tower sections as they are being assembled and permit the upper end of tower section  44  to roll along the inner surface of tower section  30  as tower section  44  is inserted into tower section  30 . Lifting brackets  56  are temporarily mounted on the lower and upper ends of the tower section  44  to which crane lines may be attached to support the respective ends of the tower section  44  while it is being inserted into the lower tower section  30  so that the tower sections  30  and  44  are positioned in nested relationship, as illustrated in FIG. 5. At this point the roller assembly  52  and the nesting brackets  56  are removed. This process is repeated for additional tower sections with each tower section being of smaller cross-sectional area and assembled in internal nested relationship to previous tower sections.  
         [0061]    As each tower sections is positioned horizontally in nested relationship within the next larger tower section, knee brackets  33  can be temporarily affixed to the lower end of the inner tower section and affixed to the internal bottom flange of the adjacent lower (outer) tower section. Brackets  33  provide vertical support of the inner tower section or sections after the nested tower sections are tilted to the upright vertical position. Guide roller mechanisms  105  and  102 , as illustrated in FIGS.  14 - 16 , and guide roller mechanisms  150  and  152 , as illustrated in FIG. 28, are installed during nesting to maintain equal circumferential spacing between tower sections.  
         [0062]    The wind turbine generator  24  may be mounted on the upper end of the inner uppermost tower section  80  while the nested tower sections are supported by support structure  42  in a generally horizontal position, as illustrated in FIG. 8, or it may be mounted after the nested tower sections are tilted into vertical position. In either case, the generator  24  is preferably mounted on tower section  80  before the nested tower sections  44  and  80  are elevated to their final extended position as shown in FIG. 18.  
         [0063]    FIGS.  8 - 13  illustrate the nested tower sections  30 ,  44  and  80 , and wind turbine generator  24  being pivoted to an upright vertical position by the use of a gin pole  58  pivotally anchored to the foundation  26 , such as at hinge points  60 . The gin pole  58  is of standard lattice construction and can be erected at the job site or transported there after assembly elsewhere. Anchor cables  61  have one end  62  affixed to the foundation  26  and the other end  63  affixed to the upper end of gin pole  58 . A winch  64  mounted on the foundation includes a lift cable  66  extending over a pulley  68  at the upper end of the gin pole  58 . The cable  66  then extends around a pulley  70  at the upper end of the lowermost outer tower section  30  with the cable  66  then going back to an anchor point  72  on the upper end of the gin pole  58 . A lightweight lift crane  73  can be used to initially lift the assembled gin pole structure from a horizontal position toward an angled vertical position, with the winch  64  keeping the cable  66  under tension.  
         [0064]    After initial lifting, as by the lightweight lift crane  73 , the continued upward tilting of the gin pole  58  is accomplished by reeling in cable  66  using winch  64  against the dead, or at rest, weight of the nested tower sections  30 ,  44  and  80 , and the generator  24  if mounted thereon, as shown in FIG. 9. Tilting of the gin pole  58  continues to its operational vertical position, angled slightly less than vertical as shown in FIGS. 10, 11 and  12 . The anchor cables  61  prevent the gin pole  58  from rising too far and conflicting with the nested tower sections  30 ,  44  and  80  and wind turbine generator  24  as they are tilted to a vertical position, as shown in FIGS. 11 and 12.  
         [0065]    Once the gin pole  58  is at its angled operational vertical position, the gin pole is then in position to assist in tilting up the nested tower sections (and generator if attached). The light weight crane  73  initially lifts the tower  20  from its horizontal position towards the vertical position (see FIG. 10), and the gin pole  58 , winch  64  and lift cable  66  complete the pivotal movement to the vertical position (see FIG. 11) by further reeling in of cable  66  with winch  64 . The gin pole  58 , winch  64  and lift cable  66  then retain the nested tower sections in vertical position (see FIG. 12), while the flange  34  is bolted securely to threaded anchor bolt couplers embedded in the foundation  26 , as illustrated in FIG. 29. With the outer tower section  30  rigidly affixed to the foundation in its prescribed vertical position, with tower sections  44  and  80  nested therein, the split hinge  28 , the gin pole  58 , cables  61  and  66  and associated structures may be removed and the tower sections may then be extended vertically to position the wind turbine generator  24  at the desired elevation.  
         [0066]    FIGS.  14 - 17  and  28  illustrate the mechanisms for extending the tower sections, including the lower or first tower section  30 , the middle or second tower section  44 , and the upper or third tower section  80 . The number of tower sections may vary depending upon the length of each tower section and the total height of the tower. However, three or more are preferred in order to utilize the automatic lifting feature of the present invention.  
         [0067]    The lower tower section  30  is rigid with the foundation  26  and includes a series of vertical jack rods  82  which are positioned at spaced locations inside the periphery of the tower section. The jack rods  82  are rigidly connected between the bottom or lower end of the tower section  30 , such as by flange  34  and a top flange  86  which extends inwardly from the top of tower section  30 . The jack rods  82  are preferably all parallel with respect to the vertical axis of tower section  30 .  
         [0068]    Vertically moveable crawler jacks  88  are mounted on each of the jack rods  82  and include a flange  90  engaged with a load member  154  adjacent the bottom end of the middle tower section  44 . In the preferred embodiments of the present invention, the second and third tower sections each have a maintenance platform  93  below the lower end of the section. The flange  90  of the moveable crawler jacks  88  is preferably engaged with temporary load member  154  attached to the skirt  94  of the maintenance platform  93  as illustrated in FIG. 28. The jacks  88  can be mounted on the jack rods prior to tilting the nested tower sections to the vertical position, in lieu of knee brackets  33 , to provide vertical support to the tower sections and prevent their sliding longitudinally as the tower moves to the vertical orientation. The crawler jacks are of conventional construction consistent with the loads required by the present invention.  
         [0069]    As the crawler jacks  88  move up or down the jack rods  82 , the middle tower section  44  will be vertically moved telescopically within the lower tower section  30 . The second or middle tower section  44  includes a series of interior or inner guide rollers  152  spaced around its lower end, such as around the bottom of the skirt  94  of platform  93  as illustrated in FIG. 28. The rollers  152  contact the inner surface of tower section  30  in order to maintain equal circumferential spacing between the bottom of the second tower section  44  in relation to the inside of lower tower section  30 .  
         [0070]    The jack rods  82  are rigidly fastened to the flange  86  at the upper end of the lower tower section  30  and extend through guide holes  91  in a peripheral flange  92  at the lower end of the middle tower section  44 , but above the maintenance skirt  94 . The flange  92  and guide holes  91  guide movement of the middle tower section  44  in relation to lower tower section  30  and also assist in maintaining equal circumferential spacing between tower sections  44  and  30 . Also mounted atop flange  86  of the lower tower section  30  are a series of external or outer rollers  150  spaced around flange  86  as illustrated in FIG. 28. The external rollers  150  engage the outside surface of the middle or second tower section  44  and further serve to properly position the middle tower section in relation to the lower section as the middle tower section is raised or lowered with respect thereto.  
         [0071]    A cable and pulley mechanism illustrated in FIGS.  14 - 17  and generally designated by reference numeral  95  automatically extends and retracts the third or top tower section  80  as the crawler jacks  88  extend or retract the middle tower section  44 . This movement is obtained by multiple cables  96  which have a fixed length and are spaced circumferentially around the tower sections  44  and  80 . One end of cables  96  is connected to the flange  86  at the upper end of the tower section  30 . Each of the cables  96  extends vertically upward over a corresponding pulley  98  mounted on inwardly extending horizontal flange  110  at the upper end of the tower section  44 . The flange  110  is oriented in spaced parallel but opposite relation to the flange  100  rigid with the exterior of tower section  80 . The cables  96  then extend downwardly through holes  109  in flange  110  and holes  111  in flange  100  on the lower end of the top or third tower section  80  (see FIG. 15). The terminal end of each cable  96  is connected to an internal sway control, generally designated by reference numeral  102  at the lower end of skirt  104  rigidly affixed to the lower flange  100  of the tower section  80 . Cables  96  lift and guide the tower section  80  telescopically in relation to the tower section  44 . The pulleys  98  mounted at the upper end of tower section  44  and which receive cables  96  are each a part of multiple external sway controls, generally designated by reference numeral  105 , which are spaced circumferentially around the tower section  80 , as illustrated in FIG. 15. The internal sway controls  102  and external sway controls  105  are aligned vertically in associated pairs which are preferably spaced equally around the circumference of middle tower section  44 .  
         [0072]    The external sway controls  105  each include a bracket mechanism  106  pivotally supported by projecting lugs  108  affixed to the flange  110  rigid with the interior of tower section  44 . Each cable  96  extends over the pulley  98  and down through openings  109  and  111  in the flanges  110  and  100  for terminal connection to the internal sway controls  102 . The bracket  106  is pivotally attached to the lugs  108  at pivot point  112  and includes a roller  113  which engages the exterior of the upper tower section  80  to guide the upper tower section  80  in relation to the middle tower section  44 .  
         [0073]    Each internal sway control  102 , such as illustrated in FIG. 16, includes a pivotal bracket  114  pivotally supported on lugs  116  at pivot point  113 . The lugs  116  are rigidly connected with the lower end of the skirt  104  on the tower section  80 . Each cable  96  is anchored to pivotal bracket  114  as at  115 , and the free end of each bracket  114  is provided with a roller  117  which engages the interior of the tower section  44 . The sway controls  102  and thus  105  maintain equal circumferential spacing between tower sections  44  and  80  and guide the telescopic movement of the tower section  80  in relation to the tower section  44 .  
         [0074]    As stated earlier, the length of the cable  96  is fixed with one end attached to the top of flange  86 . This attachment includes a spring compensation assembly, generally designed by reference numeral  119 , illustrated in FIG. 17, in the form of a plurality of stacked Belleville washers  120  mounted between an end ferrule  122  on the cable  96  and a bracket  124  that is rigidly affixed to the flange  86  which, in turn, is rigid with the upper end of the lower tower section  30 . Each of the pivotal brackets  106  and  114  are provided with stop blocks  107  and  118 , respectively, to limit the movement of the pivotal brackets and the rollers mounted thereon.  
         [0075]    A plurality of jack rods, crawler jacks, cables, cable compensators, internal sway controls and external sway controls are provided in circumferentially spaced relation to the tower sections in order to stabilize the upper tower sections as they are extended. In the preferred embodiments, such components are equally spaced around the tower circumference. Also, preferably, the flanges  92  and  86  are bolted together such as by bolts  121 , see FIG. 19, and the flanges  100  and  110  are similarly bolted together after the tower sections  44  and  80  have been fully extended to provide a rigid extended tower. Temporary guy wires (not shown) can be associated with the upper tower sections while the tower sections are being telescopically extended to stabilize the extended tower sections during erection.  
         [0076]    [0076]FIGS. 20, 20A and  24 - 27  disclose a ladder structure  130  mounted internally of the tower  20  with the ladder including three segments, each corresponding to the length of the respective tower section in which it will be mounted. The uppermost ladder section  142  in the uppermost tower section  80  is assembled and rigidly installed in the shop on the interior of the wall of the tower section  80  by vertically spaced brackets  143  rigidly attached to the inner surface of the tower section  80  and supporting the uppermost ladder section  142  spaced inwardly from the interior surface of the tower section  80 . The ladder section  146  for tower section  30  and ladder section  144  for tower section  44  include temporary mounting of ladder supporting brackets  145  that are folded downward and against the ladder sections and held in folded position by tape or tie straps to permit the two sections  144  and  146  to be nested within the installed ladder section  142  in tower section  80 . After the tower sections are nested at the job site and before the tower is tilted vertically, the bottoms of each nested ladder section  144  and  146  are affixed to horizontal pivot members  134  at the bottom of each tower section  30  and  44  respectively. As the tower sections  44  and  80  are extended vertically, the nested ladder sections  144  and  146  are automatically withdrawn from their nested position and extend in longitudinal relation to each tower section  30  and  44 .  
         [0077]    Tower sections  30  and  44  are provided with maintenance platforms  93  at the bottom of skirts  94  and  104  respectively, each platform having a slotted guide (not shown) that guides the ladder sections  144  and  146  as they are withdrawn from their nested position in relation to ladder section  142  during the tower raising operation and aligns the ladder segments for final assembly after the tower is fully raised.  
         [0078]    After the tower sections are completely extended, the ladder segments  144  and  146  are temporarily supported by a cable winch (not shown) from the top of the tower section  80  and the pivotal member  134  associated with each ladder section  144  and  146  is moved to a final position. The ladder section  146  in tower section  30  is illustrated in FIGS.  24 - 27  and is supported on a pivot member  134  supported in a slotted pivotal bracket  136  with the ladder segment  146  being lifted slightly while plate  139  is removed. The ladder section  146  is lowered and member  134  moves downwardly in slotted bracket  136  into final position on a stop block  138 . The supporting structure for the inclined slotted bracket  136  and ladder section  146  includes bracket structures  140  for attachment to the floor of the tower section  30  formed by foundation  26 .  
         [0079]    The internal ladder brackets  145  are then unfolded and attached in any suitable manner to the inner wall of tower sections  44  and  30 . The internal ladder sections provide access to the maintenance platforms  93  to facilitate an operator&#39;s gaining access to the components of the tower sections to rigidly bolt the tower sections together and to enable service access to wind turbine generator  24  affixed to the upper end of the uppermost tower section  80 .  
         [0080]    The lower tower section  30  is provided with an access opening and closure door or panel (not shown) in the peripheral wall to provide access to the interior of the tower  20 . Also, each of the maintenance platforms have an opening with a closure door aligned with the ladder sections above and below each platform. This enables access to each tower section and enables the platform to be continuous when the door is closed to enable personnel to move around without danger of falling through the opening. The lower tower section  30  and ladder section  146  may have a platform  93  or floor having an access opening with a door to provide access to the recess or cavity  126  in the upper end of foundation  26  which is adapted to receive switchgear, controls  190  or the like positioned on the bottom  192  of cavity  126  as illustrated in FIG. 20.  
         [0081]    FIGS.  21 - 23  illustrate an alternate lifting mechanism for telescopically extending the middle tower section  44  with relation to bottom tower section  30 . As shown, circumferentially spaced lift mechanisms, each consist of a winch  150 , cable  160  and pulley  170 . Winches  180  and guy lines  182  are utilized in this embodiment to provide stability to the top of the tower section  80  as it extends telescopically with relation to tower section  44 . As illustrated in FIG. 21, movement of cable  160  will lift or lower tower section  44  which will automatically extend the uppermost tower section  80  in the same manner as described and illustrated in FIG. 14 with the crawler jacks being replaced by cables  160  and winches  150 .  
         [0082]    While the tower sections  30 ,  44  and  80  are preferably circular in cross-section, it may be possible to use different nesting shapes such as triangular, square or the like. Further, the section walls need not always be solid, but may have openings or even a lattice structure.  
         [0083]    The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be utilized, falling within the scope of the invention.