Abstract:
An adjustable scaffold base for straddling ground level obstructions, such as church pews and other fixed, ground level structures, and supporting an upwardly-extending scaffold tower thereon. The scaffold base incorporates four legs and four elevated, height-adjustable cross beams that allow a scaffold tower to be erected above the height of many fixed, ground level structures. The erected base and tower thereby allow workers to access elevated areas within high-ceilinged buildings, such for performing ceiling repairs, painting, and changing light bulbs.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/351,320 filed Jun. 4, 2010. 
    
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT 
     (Not Applicable) 
     REFERENCE TO AN APPENDIX 
     (Not Applicable) 
     BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of scaffolding and more particularly to an adjustable scaffold base for allowing scaffold towers to be erected above ground level obstructions. 
     Traditionally, it has generally been difficult to change light bulbs or perform other high-elevation indoor maintenance tasks, such as painting or repairing ceiling surfaces, in churches, theaters, stadiums or other buildings that have high ceilings and that also have permanently-fixed ground level obstructions, such as pews or other fixed seating structures. Traditional frame-scaffolding that would normally be erected to facilitate high-elevation maintenance tasks is generally inappropriate for environments that include ground level obstructions because the spacing between the frame legs of such scaffolding typically does not match the spacing around pews or other large or irregularly-shaped obstructions. Even if the frame spacing of traditional scaffolding could be made to coincide with the spacing around ground level obstructions, the necessary cross-bracing between the scaffold frames would hit the obstructions. Furthermore, the legs supporting the scaffolding may have to bear on surfaces that can be 45 inches or more out of level with one another, whereas typical scaffolding leveling jacks that are normally employed to accommodate uneven surfaces only have about 14 inches of vertical adjustment. Still further, typical scaffold frames are only wide enough to support freestanding structures that are approximately 20 feet tall, which is not tall enough to reach the ceilings of many buildings. 
     It is possible for scaffold companies to build tube-and-clamp scaffolding structures that accommodate environments that present immovable, ground level obstructions, but the cost of labor and equipment to erect such structures is often prohibitively expensive. It would therefore be desirable to provide a relatively low-cost, highly adjustable scaffolding system that can be erected around immovable, ground level obstructions for accommodating high-elevation tasks such as replacing light bulbs and painting or repairing ceiling surfaces. 
     It is therefore an object and feature of the present invention to provide a low-cost means for allowing a conventional scaffold tower to be erected in a manner that avoids ground level obstructions. It is a further object and feature of the present invention to provide such a means that is suitable for supporting a conventional scaffold tower having a height that is sufficient for allowing a worker to reach the ceiling of a church or other such building having high ceilings. It is a further object and feature of the present invention to provide such a means that can be easily moved while still fully erected. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided an adjustable scaffold base for supporting a conventional scaffold tower at an elevated position above ground level obstructions. The scaffold base includes four elongated, upstanding primary legs that are spaced apart in a parallel relationship with one another. A first lateral beam extends between two of the primary legs in a perpendicular relationship therewith, and a second lateral beam extends between the other two of the primary legs in a perpendicular relationship therewith and in a parallel relationship with the other lateral beam. Each primary leg extends through a primary leg sleeve that is rigidly affixed to an adjacent end of the primary leg&#39;s respective lateral beam. Each primary leg sleeve can slidably move along its respective primary leg, thereby allowing each lateral beam to move up and down along the length of its respective pair of primary legs. Each primary leg sleeve can be removably secured at a plurality of positions along the length of its respective primary leg by extending a pin through a pair of axially-aligned positioning holes formed in the primary leg and its respective primary leg sleeve. 
     First and second frame beams extend across, and are removably secured to, the first and second lateral beams in a perpendicular relationship therewith and in a spaced, parallel relationship with one another. Each frame beam can be removably secured at a plurality of positions along the length of each lateral beam. A pair of frame posts extends upwardly from each of the frame beams in a perpendicular relationship therewith and in a spaced relationship with one another for engaging and rigidly supporting the scaffold frames of a conventional scaffold tower. A scaffold tower can thus be erected and supported atop the scaffold base, with the scaffold base straddling and avoiding ground level obstructions, such as church pews or other fixed, ground level structures. 
     The erected scaffold base and scaffold tower can be easily moved by inserting four auxiliary legs into vertically-oriented auxiliary leg sleeves that are rigidly affixed to the ends of the frame beams. Conventional casters are mounted to the bottom ends of the auxiliary legs. All of the auxiliary legs are lowered within their respective auxiliary leg sleeves until their casters are in contact with the surface upon which the scaffold base stands. The positions of the auxiliary legs are then secured by inserting pins through aligned pairs of positioning holes in the auxiliary leg sleeves and the auxiliary legs. Each of the primary legs is then raised within its primary leg sleeve and is secured at an elevated position, thereby leaving the scaffold base and the scaffold tower supported solely by the auxiliary legs and casters. The scaffold base can then be rolled upon the casters to a desired location, after which the primary legs can again be lowered and secured. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1   a  is an exploded, perspective view illustrating the legs, feet, and lateral beams of the scaffold base present invention. 
         FIG. 1   b  is a perspective view illustrating the assembled legs, feet, and lateral beams of the scaffold base of the present invention. 
         FIG. 2   a  is a perspective view illustrating the assembled legs, feet, lateral beams, and frame beams of the scaffold base of the present invention. 
         FIG. 2   b  is a detail view illustrating the mounting bracket of a frame beam of the present invention. 
         FIG. 3   a  is a partially exploded perspective view illustrating the legs, feet, lateral beams, frame beams, and cross brace of the present invention. 
         FIG. 3   b  is a perspective view illustrating the fully assembled scaffold base of the present invention. 
         FIG. 4   a  is a front view illustrating the scaffold base of the present invention with the lateral beams mounted to the outsides of the mounting brackets of the frame beams. 
         FIG. 4   b  is a front view illustrating the scaffold base of the present invention with the lateral beams mounted to the insides of the mounting brackets of the frame beams. 
         FIG. 5  is a perspective view illustrating a pair of scaffold frames mounted to the scaffold base of the present invention. 
         FIG. 6  is a perspective view illustrating a pair of cross braces mounted to the scaffold frames shown in  FIG. 5 . 
         FIG. 7  is a perspective view illustrating a pair of guard rails and work platforms mounted to the scaffold frames shown in  FIG. 6 . 
         FIG. 8  is a perspective view illustrating guardrail posts mounted to the scaffold frames shown in  FIG. 7 . 
         FIG. 9  is a perspective view illustrating the scaffold base of the present invention with swivel plates mounted to the legs. 
         FIG. 10  is a perspective view illustrating the scaffold base of the present invention with leveling jacks mounted to the legs. 
         FIG. 11  is a perspective view illustrating the scaffold base of the present invention with auxiliary legs having casters mounted to the frame beams. 
     
    
    
     In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. 
     DETAILED DESCRIPTION OF THE INVENTION 
     This application claims the benefit of U.S. Provisional Application No. 61/351,320, which is incorporated herein by reference. 
     Referring to  FIGS. 1   a - 4   b , an adjustable scaffold base for straddling ground level obstructions, such as church pews and other fixed structures, and supporting an upwardly-extending scaffold tower is indicated generally at  10 . The scaffold base  10  is defined by four feet  12   a - d , four primary legs  14   a - d , two lateral beams  16  and  18 , two frame beams  20  and  22 , and a cross brace  24 . Unless otherwise noted below, all of the components of the scaffold base  10  are fabricated from steel members and preferably square steel tubing members in particular. The use of any other suitable material, or combination of materials, such as aluminum, plastic and various composites, is contemplated and will be understood by the person having ordinary skill. 
     For the sake of convenience and clarity, terms such as “top,” “bottom,” “up,” “down,” “inwardly,” “outwardly,” “lateral,” and “longitudinal” will be used herein to describe the relative placement and orientation of various components of the invention, all with respect to the geometry and orientation of the fully assembled scaffold base  10  as it appears in  FIG. 3   b.    
     Referring to  FIG. 1   a , each foot  12   a - d  of the scaffold base is defined by a planar, preferably rectangular base plate  26   a - d , such as may be formed from wood or steel, with a tubular neck  28   a - d  formed of a segment of round steel tubing rigidly affixed thereto in a perpendicular relationship therewith. Each foot  12   a - d  is positioned on a support surface, such as the floor of a building, with the bottom of each base plate  26   a - d  engaging the support surface and with the tubular neck  28   a - d  of each foot  12   a - d  extending upwardly therefrom. The support surface is typically an indoor flooring surface such as stone, brick, tile, or carpet, but could alternatively be soil, pavement or other outdoor surfaces. Of course, the flat base plates  26   a - d  can be replaced by wheels or narrow legs. 
     Referring to  FIG. 1   b , each lateral beam  16  and  18  of the scaffold base  10  is formed of an elongated segment of rectangular steel tubing that is preferably 7 feet, 9 inches in length, although it is contemplated that the lateral beams  16  and  18  can be made shorter or longer to suit various applications. Each lateral beam  16  and  18  has a series of positioning holes  30  formed through it that are spaced on 16 inch centers, wherein each positioning hole  30  provides a transverse, lateral passageway through its respective lateral beam  16  and  18 . An example of an acceptable diameter for each positioning hole  30  in the lateral beams  16  and  18  is 0.625 inches. The term “hole” is often used hereinafter to refer to a pair of axially aligned apertures, wherein one of the apertures is positioned on one sidewall of a hollow body, such as a tube, and the other aperture is positioned on the opposing sidewall. Each “hole” thereby provides a single passageway through the entire body, even though only one of the apertures of the hole is depicted in the illustrations. For example, only one of the apertures in each hole-pair is depicted in  FIGS. 1   a  and  1   b . The other apertures are on the opposite side of the structures but are impossible to show in an illustration of a three dimensional object. 
     Each lateral beam  16  and  18  terminates at each of its longitudinal ends in a primary leg sleeve  32   a - d  that is formed of a short segment of square steel tubing that is rigidly connected to its respective lateral beam  16  and  18 , such as by welds, in a perpendicular relationship therewith. Each primary leg sleeve  32   a - d  has positioning holes  34  formed through it that are spaced on 1.25 inch centers along the sleeve&#39;s length. Flat steel segments  36   a - d  are preferably welded to the primary leg sleeves  32   a - d  and to their respective lateral beams  16  and  18  for enhancing the strength and rigidity of the connections between the primary leg sleeves  32   a - d  and the lateral beams  16  and  18 . Although incorporation of the leg sleeves  32   a - d  is preferred, it is contemplated that the leg sleeves  32   a - d  can be omitted and that the vertically-oriented holes can alternatively be formed through the lateral beams  16  and  18  for accepting the primary legs  14   a - d  (as described below). 
     Referring to  FIG. 1   a , each of the primary legs  14   a - d  of the scaffold base  10  is formed of an elongated segment of square steel tubing that preferably measures 5 feet in length. It is contemplated that the primary legs  14   a - d  can be made shorter or longer than 5 feet, and that one or more of the primary legs  14   a - d  can have a length that is different than one or more of the other primary legs  14   a - d . Each primary leg  14   a - d  has a series of groups of three positioning holes  38  formed through it, with the positioning holes  38  in each group being spaced on 2 inch centers and with each group spaced 8 inches apart, thus allowing ½ inch vertical adjustment of the primary legs  14   a - d . Referring to  FIG. 1   b , each primary leg  14   a - d  extends through, and axially engages, a primary leg sleeve  32   a - d  of one of the lateral beams  16  and  18  (described above), with two of the primary legs  14   a - d  thus mounted to each lateral beam  16  and  18  in a parallel relationship and at a fixed distance apart from one another. The exterior dimensions of the primary legs  14   a - d  are slightly smaller than the interior dimensions of the primary leg sleeves  32   a - d  in order that the primary leg sleeves  32   a - d  may snugly receive the primary legs  14   a - d  while allowing sliding axial movement of the primary leg sleeves  32   a - d , and therefore the lateral beams  16  and  18 , relative to the primary legs  14   a - d . Threaded stability bolts (not shown) preferably extend horizontally through a corner of each primary leg sleeve  32   a - d  with the flats tips of the bolts engaging the primary legs  14   a - d  within the sleeves. By tightening the bolts against the primary legs  14   a - d  the primary legs  14   a - d  can be stabilized against excessive lateral movement within their respective primary leg sleeves  32   a - d.    
     The bottommost ends of the primary legs  14   a - d  fit over and axially engage the necks  28   a - d  of the feet  12   a - d , thereby rigidly supporting the primary legs  14   a - d  in a vertical orientation. Alternative embodiments of the scaffold base  10  are contemplated in which the primary legs  14   a - d  are permanently mounted to the lateral beams  16  and  18  in a fixed position and are not slideably adjustable relative thereto. 
     In order to adjust the heights of the lateral beams  16  and  18 , such as to a height above fixed, ground level obstructions (described in greater detail below), the primary leg sleeves  32   a - d  of each lateral beam  16  and  18  can be slid upwardly or downwardly along their respective primary legs  14   a - d . Since each lateral beam  16  and  18  is fixed at both of its longitudinal ends to a respective, vertically-oriented primary leg  14   a - d  in a substantially perpendicular orientation therewith, the lateral beams  16  and  18  will remain in a substantially horizontal orientation as they are moved vertically along their respective primary leg-pairs. After each lateral beam  16  and  18  has been moved to a desired height at least one of the positioning holes  34  in each primary leg sleeve  32   a - d  is brought into axial alignment with a closest positioning hole  38  in a respective primary leg  14   a - d . Pins  40   a - d  are then inserted through each pair of aligned positioning holes  34  and  38  to secure the primary leg sleeves  32   a - d  against vertical movement along the primary legs  14   a - d , thereby fixing the lateral beams  16  and  18  at the desired height. The pins  40   a - d  are preferably standard, spring-loaded, positive locking pins having an outer diameter that is slightly smaller than the diameter of the respective holes through which they pass. However, all other types of fastening means, such as screws, bolts, rivets, clamps, non-spring-loaded pins, and friction mounts are also contemplated. 
     Referring to  FIG. 2   a , the frame beams  20  and  22  are similar in construction and size to the lateral beams  16  and  18 , including auxiliary leg sleeves  42   a - d  mounted to the longitudinal ends of the frame beams  20  and  22  that are substantially identical to the primary leg sleeves  32   a - d  described above. Unlike the lateral beams  16  and  18 , the frame beams  20  and  22  do not have positioning holes formed in them. Each frame beam  20  and  22  includes a pair of frame posts  44   a - d  formed of short segments of square steel tubing that are rigidly mounted to, and that extend upwardly from, the frame beams&#39; top surfaces. The frame posts  44   a - d  on each frame beam  20  and  22  are preferably spaced 5 feet apart from one another and are equidistant from the nearest longitudinal ends of their respective frame beam  20  and  22 , although it is contemplated that this spacing can be varied from the preferred distances. 
     A pair of positioning brackets  50   a - d  is rigidly mounted to the underside of each frame beam  20  and  22 , with each positioning bracket  50   a - d  positioned about 4.5 inches inward from a nearest longitudinal end of the frame beam  20  and  22 . The positioning brackets  50   a - d  preferably measure 6 inches long and are formed of rectangular blocks of steel. Each positioning bracket  50   a - d  has a 0.625 inch diameter positioning hole (not within view) extending horizontally through it for receiving a threaded bolt of a slightly smaller diameter (as described below), as best shown in  FIG. 2   b.    
     When operatively positioned, the frame beams  20  and  22  rest on top of, and extend perpendicularly across, the lateral beams  16  and  18 , with each lateral beam  16  and  18  positioned inward of the auxiliary leg sleeves  42   a - d  and outward of the positioning brackets  50   a - d  of the frame beams  20  and  22  as best shown in  FIGS. 2   a  and  4   a . The frame beams  20  and  22  are preferably spaced 4 feet apart in a parallel relationship with one another, and with the positioning holes in the positioning brackets  50   a - d  aligned with corresponding positioning holes  30  in the lateral beams  16  and  18 . Threaded bolts extend outwardly, through the positioning holes in the positioning brackets  50   a - d  and through the positioning holes  30  in the lateral beams  16  and  18 . Nuts threadedly engage the outermost ends of the bolts, thereby securing the frame beams  20  and  22  to the lateral beams  16  and  18 . Configured thusly, the lateral beams  16  and  18  are spaced 7 feet apart. Alternatively, if the spacing between the lateral beams  16  and  18  must be less than 7 feet, such as for adjusting the spacing between the primary legs  14   a - d  to avoid ground level obstructions, the lateral beams  16  and  18  can be secured to the innermost sides of the positioning brackets, as shown in  FIG. 4   b . The threaded bolts extend inwardly through the positioning brackets  50   a - d  and the lateral beams  16  and  18  and with the nuts engaging the innermost ends of the bolts, in which case the lateral beams  16  and  18  are spaced 6 feet apart. It is also possible to secure one of the lateral beams  16  and  18  to the outermost side of its corresponding positioning brackets  50   a - d  and secure the other lateral beam  16  and  18  to the innermost side of its positioning brackets  50   a - d , in which case the lateral beams  16  and  18  are spaced 6 feet 6 inches apart. Alternative embodiments of the scaffold base are contemplated wherein the positioning brackets  50   a - d  are omitted and the frame beams  20  and  22  are rigidly connected to the lateral beams  16  and  18  in a fixed position, such as by welds or conventional fasteners. 
     Referring to  FIGS. 3   a  and  3   b , the cross brace  24  is formed of two elongated segments of steel angle that are fastened together in a perpendicular relationship, such as with a rivet, to form an X-shaped member. The cross brace spans across, and is rigidly fastened to, the undersides of the frame beams  20  and  22 , such as with conventional nut-bolt combinations that engage apertures formed through the cross brace  24  and the frame beams  20  and  22 , for providing the scaffold base  10  with added strength and rigidity. It is contemplated that the cross brace  24  can be rigidly fastened to the frame beams  20  and  22  in any other suitable manner. It is further contemplated that the cross brace  24  can be omitted or that other bracing means, such as additional lateral or longitudinal frame members installed intermediate the frame beams  20  and  22  and the lateral beams  16  and  18 , can additionally or alternatively be incorporated into the scaffold base  10 . 
     Referring to  FIG. 5 , once the scaffold base  10  has been erected at a desired location and the lateral beams  16  and  18  have been adjusted to a desired height, such as above the height of ground level obstructions that would prevent the erection of traditional scaffold towers, conventional scaffold frames  60  and  62  can be connected to the elevated frame beams  20  and  22 . Particularly, elongated stack pins (not shown) that extend from, and are rigidly connected to, the uppermost ends of the vertical members of the scaffold frames  60  and  62  axially engage the frame posts  44   a - d  and are securely held therein in a vertical orientation. The scaffold frames  60  and  62  thereby span across the frame beams  20  and  22  and are secured in a vertical orientation and in a parallel relationship with one another. Referring to  FIG. 6 , the scaffold frames  60  and  62  are preferably secured to one another with conventional cross braces  64  and  66 . Finally, referring to  FIG. 7 , conventional guardrails  68  and  70  and aluminum work platforms  72  and  74  are secured to the scaffold frames  60  and  62  to complete the scaffold tower  76 . If more height is required, additional frame members and guardrails can be added to the scaffold frames  60  and  62  in a conventional manner and the work platforms  72  and  74  can be secured at a higher position on the scaffold tower  76 , as shown in  FIG. 8 . During testing it has been demonstrated that the scaffold base  10  is capable of stably supporting free-standing scaffold structures measuring over 150 feet in overall height. 
     If the scaffold base  10  must be positioned on a sloped surface, such as on an auditorium aisle way or on a wheelchair ramp, it is contemplated that conventional swivel plates  80   a - d  can be substituted for one or more of the feet  12   a - d , as shown in  FIG. 9 , for allowing the primary legs  14   a - d  to extend vertically from the sloped surface. It is further contemplated that one or more of feet  12   a - d  can be replaced by screw-threaded leveling jacks  82   a - d , as shown in  FIG. 10 , for allowing the heights of the primary legs  14   a - d  to be finely adjusted and leveled to optimize the stability of a scaffold tower erected thereon. Those skilled in the art will recognize that various other mounting accessories can be substituted for one or more of the feet  12   a - d  without departing from the spirit of the invention. 
     Referring to  FIG. 11 , the erected scaffold base  10  and tower can be conveniently moved through the use of auxiliary legs  90   a - d  that are fitted with casters  92   a - d . This is accomplished by inserting the auxiliary legs  90   a - d  into the auxiliary leg sleeves  42   a - d  (described above) of the frame beams  20  and  22  from above, after which conventional scaffold casters  92   a - d  are mounted to the bottom ends of the auxiliary legs  90   a - d . The auxiliary legs  90   a - d  engage the auxiliary leg sleeves  42   a - d  of the frame beams  20  and  22  in a substantially identical manner to the engagement between the primary legs  14   a - d  and the primary leg sleeves  32   a - d  of the lateral beams  16  and  18  described above. The height of each auxiliary leg  90   a - d  relative to its respective auxiliary leg sleeve  42   a - d  can similarly be adjusted and secured by sliding the auxiliary legs  90   a - d  vertically within their respective auxiliary leg sleeves  42   a - d  to a desired height and inserting pins through aligned pairs of positioning holes in the auxiliary leg sleeves  42   a - d  and the auxiliary legs  90   a - d . It is contemplated that the primary legs  14   a - d  can also be fitted with castors for further improving the mobility of the scaffold base  10 . 
     To move the scaffold base  10 , all of the auxiliary legs  90   a - d  are lowered until their respective casters  92   a - d  are in contact with, or are nearly in contact with, the surface upon which the feet  12   a - d  of the scaffold base  10  rest. The vertical positions of the auxiliary legs  90   a - d  are then secured. Each of the primary legs  14   a - d  is then raised within its primary leg sleeve  32   a - d  and is secured at an elevated position, thereby leaving the scaffold base  10  and the scaffold tower supported solely by the auxiliary legs  90   a - d  and casters  92   a - d . Alternatively, the primary legs  14   a - d  can be entirely removed from their respective primary leg sleeves  32   a - d  (which requires removal of the feet after the primary legs  14   a - d  have been raised a short distance off the support surface). The scaffold base  10  can then be rolled upon the casters  92   a - d  to a desired location. Since the auxiliary legs  90   a - d  are spaced only four feet apart from one another, the scaffold base  10  can easily fit through most aisle ways and other narrow areas while the elevated lateral beams  16  and  18  and primary leg sleeves  32   a - d  move above ground level obstructions (i.e., if the primary legs  14   a - d  have been entirely removed from, or sufficiently raised in, the scaffold base  10 ). Once the scaffold base  10  has been moved to a desired location, the primary legs  14   a - d  and feet can be reinstalled and repositioned to support the scaffold base  10  in the manner described above, and the auxiliary legs  90   a - d  and casters  92   a - d  can be raised or entirely removed from the scaffold base  10 . 
     This detailed description in connection with the drawings is intended principally as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.