Patent Publication Number: US-6710751-B2

Title: Rotatable platform for lattice towers

Description:
BACKGROUND OF INVENTION 
     This application claims the benefit of the U.S. Provisional Patent Application, Serial No. 60/306,579 filed Jul. 19, 2001, the complete disclosure of which is hereby expressly incorporated herein by reference. 
     Antenna poles or towers have long been in use for transmission, reception and forwarding of radio and television signals. In addition, microwave antennae have come into frequent demand and usage for cellular communications. Such poles or towers generally range in height from 80 to 220 feet or more. It is also common to place an antenna support or platform upon the poles or towers for mounting antennae thereto for reception and transmission of signals. It is common for the antenna platforms to have a generally triangular shape, such as is shown in U.S. Pat. No. 5,787,673 to M. Noble, herein incorporated by reference. 
     It has been found that lattice-type towers provide an economical, efficient and stable support for mounting an antenna platform. Lattice towers often consist of a generally triangular-shaped framework utilizing a truss-type construction. 
     One drawback of lattice towers for supporting an antenna platform is the fact that it has been heretofore unknown to have a means or method to readily rotate an antenna platform about a lattice tower. This is because the triangular shape of lattice towers does not readily accommodate a rotational mechanism. It is desirable to have this ability to rotate the platform so that the receiving and transmitting of signals may be optimized. 
     It is therefore an object of the invention to provide a rotatable antenna platform and mount that is suitable for use on a lattice tower. It is a further object of the invention to provide such rotatable means in an efficient and economical manner. 
     SUMMARY OF THE INVENTION 
     It is a feature of the invention to provide a tower, an antenna platform and a mounting assembly for rotatably mounting the antenna platform to the tower. The antenna platform of the embodiment shown includes a frame and antenna mounting members. The tower is a lattice-type tower and includes three vertical support legs joined to one another by trusses. 
     In one embodiment, the mounting assembly includes tower mounting members for attaching the mounting assembly to the tower, platform mounting members for attaching the antenna platform to the mounting assembly, and rotational members to facilitate rotation of the antenna platform about a longitudinal axis of the tower. The mounting assembly enables the antenna platform to be set at any desired position about a 360-degree azimuth. 
     In an embodiment shown, the rotational members include a ring. The ring may include ring segments. This embodiment has three ring segments and the mounting assembly allows rotation of the antenna platform along a 120-degree arc while the platform is connected to the tower. The platform mounting members are attached to the ring between the segments thereof. 
     It is also an embodiment of the invention, that the platform mounting members have a plate and a gusset, and the ring segments have flanges attached to the ends thereof. The flanges of the ring segments are attached to a gusset on one of the platform support brackets. 
     The ring may be mounted to be slidable relative to the tower mounting members. Furthermore, the ring may be secured to preclude slidable movement relative to the tower mounting members. In one embodiment, the ring is mounted to the tower mounting members with U-bolts. 
     It is also an aspect of the invention to provide centering clamps to maintain centering of the platform with respect to the longitudinal axis of the tower while the rotational members are being rotated. In the embodiment shown, the centering clamps are attached to the tower mounting members and have a T-shape including a center flange. The flange is perpendicular to a retaining plate. The centering clamps are positioned to be juxtaposed the inner diameter of the ring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a lattice tower having a rotatable antenna platform according to the subject invention mounted thereon; 
     FIG. 2 is a perspective view of the lattice tower with tower mounting members attached thereto; 
     FIG. 3 is a perspective view of the lattice tower showing rotational members mounted to the tower mounting members; 
     FIG. 3A is a perspective view of the lattice tower showing the rotational members rotated to 120° stopping point when the rotational members are mounted to the tower mounting members; 
     FIG. 3B is a perspective view of the lattice tower showing the rotational members rotated to the opposite stopping point when the rotational members are mounted to the tower mounting members; 
     FIG. 4 is a plan view of the rotatable antenna platform and mounting assembly with the tower and platform shown in phantom lines; 
     FIG. 5 is a side view of the lattice tower, rotatable antenna platform, and mounting assembly with the tower and platform shown in phantom lines; 
     FIG. 6 is a close up top view taken from FIG. 4 of a portion of a ring segment of the rotatable mounting assembly mounted to a tower mounting member; 
     FIG. 7 is a cross sectional view taken as shown in FIG. 6 of the ring segment mounted to the tower mounting member; 
     FIG. 8 is a close up top view taken from FIG. 4 of the mounting of a pair of ring segments to the antenna platform with the antenna platform shown in phantom lines; 
     FIG. 9 is a side cross sectional view taken as shown in FIG. 8 of the mounting of the pair of ring segments to the antenna platform with the antenna platform shown in phantom lines; 
     FIG. 10 is a plan view of a single ring segment; 
     FIG. 11 is cross sectional view of the ring segment of FIG. 10; 
     FIG. 12 is a plan view of the ring segment of FIG. 10 having end flanges attached thereto; 
     FIG. 13 is a side view of the ring segment of FIG. 12 with the end flanges attached; 
     FIG. 14 is an end view of the ring segment of FIG. 12 with the end flanges attached; 
     FIG. 15 is a plan view of a platform support bracket for the rotatable platform mount; 
     FIG. 16 is a side view of the platform support bracket of FIG. 15 for the rotatable platform mount; 
     FIG. 17 is an end view of the platform support bracket of FIG. 15 for the rotatable platform mount; 
     FIG. 18 is a side view of a centering clamp for the rotatable platform mount; 
     FIG. 19 is a top view of the centering clamp of FIG. 18 for the rotatable platform mount; and 
     FIG. 20 is an end view of the centering clamp of FIG. 18 for the rotatable platform mount. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the FIG. 1, a lattice tower is shown generally indicated as  10 . The lattice tower has an antenna platform generally indicated as  12  that is rotatably mounted thereupon with a mounting assembly generally indicated as  14 . The lattice tower  10  has a generally triangular configuration and includes three generally vertically oriented structural support legs  16  which are secured to one another with truss members/braces  18 . Lattice tower  10  is oriented along a longitudinal axis A as shown in FIGS. 4 and 5. 
     Antenna platform  12  also has a generally triangular shape and includes horizontal members  20 , an outer frame  22  and vertically oriented antenna mounting pipes  24 . Between the horizontal members  20  are radially aligned horizontal supports  26 . The lattice tower and antenna platform described above are both well known in the art. 
     The mounting assembly  14  generally includes tower mounting members  30  (FIG.  2 ), a circular ring generally indicated as  36  (FIG. 3) and platform mounting members/support brackets generally indicated as  38 , as are best shown in FIGS. 6-9. In the embodiment shown, the tower mounting members  30  are formed from box-shaped structural members and have an end flange  31  attached thereto. The tower mounting members are attached to the lattice tower  10  using mounting brackets  32 , bolts  34 , and nuts  35  or other attachment means well known in the art. The bolts  34  are positioned in mating apertures (not shown) in end flanges  31  and brackets  32 . 
     As shown in FIG. 3, ring  36  includes three ring segments  40   a ,  40   b ,  40   c , which are supported upon the tower mounting members  30 . The ring segments are held firmly to the tower mounting members  30  with mounting hardware including U-bolts  48 , mounting plates  50 , and nuts  52 , as best shown in FIG.  7 . The U-bolts straddle the mounting members  30  and extend through the mounting plates  50  to be secured thereto with the nuts  52  as detailed below. 
     The ring segments  40   a ,  40   b ,  40   c  each extend approximately 120 degrees about the ring  36 . An embodiment of the ring segments  40   a ,  40   b ,  40   c  is shown in FIGS. 10 and 11. In this embodiment, ring segments  40   a ,  40   b ,  40   c  are shaped in an arc of approximately 120 degrees. The arc of ring segments  40   a ,  40   b ,  40   c  is formed about a radius wherein the inner side of the segment is formed along a radius R I  Radius R C  coincides with the center of the ring segment. As shown in FIG. 11, ring segments  40   a ,  40   b ,  40   c  are made from a hollow circular structural member. Flanges  54  are attached to each end  55  of ring segments  40   a ,  40   b ,  40   c  and the flanges have apertures  56  extending therethrough as shown in FIGS. 12-14. 
     One platform mounting member  38  is located between each ring segment and extends outwardly therefrom. The end flanges  54  of the ring segments  40   a ,  40   b ,  40   c  are attached to the respective platform mounting member  38  located therebetween using bolts  57  and nuts (not shown) as will be discussed in more detail below. 
     The platform mounting members  38  are detailed in FIGS. 15-17. Each platform mounting member has a gusset  60  and a mounting plate  62 . Gusset  60  is mounted perpendicular to mounting plate  62  in approximately the central portion thereof using an arc welding process or other attachment means well known in the art. Gusset  60  includes through apertures  64  and mounting plate  62  includes elongated through apertures  66 . 
     Now referring to FIGS. 6 and 7, it can be seen that mounting assembly  14  also includes centering clamps generally indicated as  67 , which are affixed to tower mounting members  30  using bolts  68 , mounting plates  69  and nuts  70 . A pair of the bolts  68  straddle each tower mounting member  30 . 
     The centering clamps  67  are depicted in detail in FIG. 18-20. Each centering clamp  42  includes a flange  71  and a retaining plate  72  having an outer edge  73 . The retaining plate is mounted to the central portion of the flange utilizing an arc welding process or other well-known joining technique. In the embodiment shown, flange  71  is rounded on the ends, and includes slotted holes  74 . Furthermore, flange  71  does not extend across the complete width of the retaining plate  72 . As is shown in FIGS. 18 and 19, flange  71  is approximately one-half the width of retaining plate  72 . 
     Additional mounting hardware included in mounting assembly  14  include bolts  76 , securing plates  78 , and nuts  80  (FIG.  9 ). 
     Having discussed the major component parts of the subject invention, the assembly and operation will now be discussed in further detail. As discussed above, the embodiment depicted in the figures utilizes a lattice-type tower. Preferably, the tower  10  is pre-fabricated before taking it to the installation site or sections of the tower  10  are pre-fabricated and erected and attached to one another at the installation site. Antenna platform  12  is likewise pre-fabricated or partially pre-fabricated before installation. To install the antenna platform  12 , the tower mounting members  30  are first attached to the vertical support legs  16  using mounting brackets  32 , bolts  34 , and nuts  35 . As discussed above, the bolts are placed through apertures in flange  31  of tower mounting members  30  and through mating apertures in bracket  32  and secured with nuts  35 . As will be apparent to one skilled in the art, tower mounting members  30  are installed at a height on the tower where it is desired to mount the antenna platform  12 . In the embodiment shown, there is one tower mounting member  30  for each vertical support leg  16  making a total of three tower mounting members. The tower mounting members  30  are mounted in a generally horizontal direction extending radially outward from the longitudinal axis A of tower  10 . 
     Next, one centering clamp  67  is attached to each tower mounting member  30  using a pair of the bolts  68 , one mounting plate  69  and a pair of the nuts  70 . The centering clamps are placed on the top of the tower mounting members  30  with plates  69  to the underside thereof. One bolt  68  is placed on each side of the tower mounting members through apertures (not shown) located in plate  69  and through apertures  74  in flange  71  of the centering clamp  67 . The bolts  68  are secured with the nuts  70 . The centering clamps  67  are located equal-distant from the vertical support legs  16  so that the outer edges  73  of retaining plates  72  extend out from longitudinal axis A at a distance equal to or slightly smaller than the inner diameter of ring  36  which coincides with radius R i  for reasons as will be explained more fully below. 
     Ring  36  is also pre-assembled prior to mounting to tower  10 . The ring is assembled such that the flanges  54  on the ends  55  of adjoining ring segments  40   a  and  40   b are attached to one of the gussets  60  on one of the platform mounting members  38  as shown in FIGS. 8 and 9. The flanges  54  are attached to the gusset by aligning apertures  56  in flanges  54  with apertures  64  in gusset  60  and connecting the flanges and gusset together using bolts  57  and nuts (not shown) or other attachment means well known in the art. When all of the flanges  54  are attached to the respective gussets  60  of platform mounting members  38 , the ring  36  appears as shown in FIG. 3 with the mounting plates  62  of platform mounting members  38  extending in a generally horizontal plane radially outward from ring  36 . 
     Ring  36  is then placed about tower  10  as shown in FIG.  3 . The platform mounting members  38  are aligned in an approximate position wherein it is anticipated the corners of generally triangular-shaped platform  12  should be placed to provide optimal transmission and receipt of signals. When fitting the ring  36  about the tower  10 , the ring is placed about centering clamps  67  so that the outer edges  73  of retaining plates  72  are adjacent to the inner side/diameter of ring  36 . In this manner, ring  36  may be rotated about the longitudinal axis A of tower  10  by sliding it upon tower mounting members  30  until the desired position is attained. The centering clamps  67  prevent lateral movement of ring  36  other than rotation thereof; therefore, the center of ring  36  will be maintained in alignment with longitudinal axis A of tower  10  as the ring is rotated. 
     When the ring is in the desired position, U-bolts  48 , which are sized to have a radius slightly larger than the outside radius of the circular cross-section of ring segments  40   a ,  40   b ,  40   c , are placed over the ring as shown in FIGS. 3,  6  and  7 . The U-bolts  48  are placed such that one is on each side of each tower mounting member  30 . The lower threaded ends of the U-bolts are placed through apertures in mounting plates  50  and secured with nuts  52 . 
     Next, the antenna platform  12  may be placed about tower  10  and attached to the platform mounting members  38 . In the embodiment shown, mounting plates  62  each contain six pairs of the elongated apertures  66 . The platform  12  is attached to the platform mounting members  38  through three pairs of elongated apertures  66 . As can be seen in FIGS. 8 and 9, the horizontal supports  26  of antenna platform  12  are attached to mounting plate  62  using three pairs of bolts  76 , securing plates  78 , and nuts  80 . The bolts are positioned through the three innermost pairs of elongated apertures  66  with each pair of bolts also extending through one of the securing plates  78  and secured with nuts  80 . As is shown, each pair of bolts straddle horizontal support  26 . If a larger diameter antenna platform  12  were mounted to ring  36 , then the outermost three pairs of elongated apertures  66  would be used to mount the platform. Of course, other hole and bolt patterns may be used based upon the size of the platform to be mounted. 
     Once mounted, if the azimuth of antenna platform  12  needs to be adjusted, the nuts  52 , which secure U-bolts  48 , may be loosened somewhat without removing the nuts completely from the threaded ends of the U-bolts. This will allow ring  36  to be slidingly rotated within a 120-degree arc in order to align the platform azimuth as desired. The range of rotation is limited to 120 degrees with the U-bolts attached as the platform mounting members  38  will come into contact with the U-bolts precluding further rotation as is shown in FIGS. 3A and 3B. If the desired azimuth cannot be attained in the 120 degree range that is available with the U-bolts loosened but still connected as- above, then U-bolts  48  may be removed and the platform moved to any desired azimuth. Of course, centering clamps  67  will keep the ring and platform centered and once the desired position has been obtained, U-bolts  48  will be repositioned and secured about the ring  36  with one on either side of each tower mounting member  30 . Of course, the above steps may be repeated whenever it is desired to realign the azimuth of the antenna platform  12 . 
     While the invention has been taught with specific reference to the embodiment detailed above and shown in the attached Figures, one skilled in the art will realize that changes may be made in form and detail without departing from the spirit and scope of the invention. First, the tower configuration is not restricted to a lattice-type tower or the particular configuration shown. Also for example, although the ring has been shown composed of three ring segments, attached to gussets of the platform mounting members, more or less segments may be used for the ring, or the ring may be made as singular piece. If a singular piece ring were used, then the platform mounting members may be attached thereto with clamps, by welding or other means well known in the art. Nor does the ring have to have a circular cross section. Also, a disc may be used instead of a ring and wheels or rollers may be used to facilitate rotation. 
     It should also be realized that a motor and gearing may be attached to the mounting assembly so that the antenna platform may be rotated automatically without the need for manual adjustment. 
     In addition, the mounting and adjusting procedure may be varied by attaching U-bolts  48  but not tightening the bolts snuggly and then rotating the ring. As discussed above; however, while the U-bolts are attached, rotation is limited to a 120-degree arc. The U-bolts must, of course, be completely removed to rotate the ring beyond this. Also, although the invention has been taught to first attach the mounting assembly to the tower prior to attaching the antenna platform to the mounting assembly, it will become apparent that the antenna platform may be pre-attached to the platform mounting members prior to attaching the assembly to the tower. However, it is more cumbersome to work with the assembly in this manner. 
     Additionally, the U-bolts that retain the ring may be mounted through optional holes in the tower mounting members (not shown) so that they are attached directly to the tower mounting members. This would eliminate the need to have separate centering clamps to maintain the ring concentric about the tower&#39;s axis. It should also be realized, that other clamp and fastener configurations may be substituted for the clamps bolts, and U-bolts depicted. The scope of the invention is therefore not limited by the figures and detailed description above, but rather, is indicated by the attached claims and equivalents thereof.