Abstract:
A workbasket assembly for surrounding and protecting a workman when cleaning or maintaining a tall structure such as a building, tank or silo. The workbasket assembly comprises a frame made up from a plurality of vertical uprights and horizontal rails connected together by a plurality of pivot tabs. The workbasket assembly may be collapsed for storage or transport purposes or so that it may be passed through a relatively small aperture in a structure such as a tank. When expanded, the workbasket assembly is engageable with a hoist-operable base that permits the workman to be safely raised or lowered relative to the structure being maintained. The frame is only movable to the fully collapsed condition when detached from the base. The workbasket assembly can be expanded and collapsed without the use of any tools.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    This invention generally relates to support structures. More particularly, the invention relates to a workbasket that is useful for cleaning the interiors or exteriors of large structures such as water towers, silos and buildings. Specifically, the invention relates to a workbasket assembly that is attachable to a hoist-operable base and is easily moved between a collapsed and an expanded condition without the use of tools. 
         [0003]    2. Background Information 
         [0004]    Large tanks are used in a wide variety of industries and operations to both store and process goods. Water towers, for example, are used to store large quantities of water for later use. Similarly, silos are used to store a wide variety of materials including grains, fermented feed, coal, cement and other bulk materials. In the power industry, boilers are used to superheat steam for the generation of electricity. The tanks utilized in these industries are tall structures that typically have relatively small access ports through which the water or other materials are introduced or removed from the structure. In silos, for example, the materials to be stored may be introduced into an access port near the top of the silo and removed from another port near the bottom of the silo. Periodically, the silo may require cleaning because the materials stored therein become compacted at the base of the silo, a condition known as bridging, or cling to the interior surfaces of the silo&#39;s side walls, a condition known as rat holing. In both instances, the flow of material from the silo is impeded and the only solution is to clean the interior of the silo. Similarly, water towers, boilers and other structures such as tall buildings periodically need to be cleaned or maintained. 
         [0005]    The interiors of large tanks are cleaned through a variety of means, one of which is manual cleaning. This requires that a workman enter the interior of the tank and be raised and lowered in a workbasket that is attached to a hoist via a steel or wire cable. The cleaning operation may be complicated by the fact that the workman, the workbasket and all the workman&#39;s equipment have to be introduced into the tank through a very small opening near the tank&#39;s base. In the case of power plant boilers, for example, these openings may only be around 18″×18″, 10″×17″ or 12″×18″ in size. The workman can enter such a size opening reasonably easily, but if a workbasket is to be used, moving the workbasket into the interior has proven to be problematic. In the past, the various components that make up the workbasket have been individually passed through the opening and into the interior of the tank. The entire workbasket has then had to be assembled within the confines of the tank&#39;s interior. After performing the cleaning or maintenance operation, the workman has had to disassemble the workbasket and pass the individual components back out through the opening. This is obviously a time consuming and labor intensive operation. 
         [0006]    There is therefore a need in the art for an improved workbasket for use in cleaning and maintenance of tall structures such as tanks and buildings. 
       SUMMARY OF THE INVENTION 
       [0007]    The device of the present invention comprises a workbasket assembly for surrounding and protecting a workman when cleaning or maintaining a tall structure such as a building, tank or silo. The workbasket assembly comprises a frame made up from a plurality of vertical uprights and horizontal rails connected together by a plurality of pivot tabs. The workbasket assembly may be collapsed for storage or transport purposes or so that it may be passed through a relatively small aperture in a structure such as a tank. When expanded, the workbasket assembly is engageable with a hoist-operable base that permits the workman to be safely raised or lowered relative to the structure being maintained. The frame is only movable to the fully collapsed condition when detached from the base. The workbasket assembly can be expanded and collapsed without the use of any tools. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The preferred embodiments of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
           [0009]      FIG. 1  is a perspective view of a workbasket in accordance with the present invention and showing the base and collapsible workbasket assembly engaged together; 
           [0010]      FIG. 2  is a perspective view of the collapsible workbasket assembly in accordance with the present invention shown detached from the workbasket and in an expanded condition; 
           [0011]      FIG. 3  is a partial cross-sectional bottom view of a gate rail on the workbasket assembly taken through line  3 - 3  of  FIG. 2 ; 
           [0012]      FIG. 4  is a partial cross-sectional side view of the gate rail taken through line  4 - 4  of  FIG. 3 ; 
           [0013]      FIG. 5  is a cross-sectional bottom view of the pivotal connection between the gate rail and upright taken through line  5 - 5  of  FIG. 4 ; 
           [0014]      FIG. 6  is a right side view of the bottom rail of the workbasket assembly taken through line  6 - 6  of  FIG. 2 ; 
           [0015]      FIG. 7  is a perspective view of the base of the workbasket with the collapsible workbasket assembly removed therefrom; 
           [0016]      FIG. 8  is a front view of the workbasket assembly showing the first stage of collapsing the same; 
           [0017]      FIG. 9  is a front view of the workbasket assembly showing the second stage of collapsing the same; 
           [0018]      FIG. 10  is a front view of the workbasket assembly showing the assembly in a partially collapsed condition; 
           [0019]      FIG. 11  is a top view of the workbasket assembly in the partially collapsed condition and taken through line  11 - 11  of  FIG. 10 ; 
           [0020]      FIG. 12  is a top view of the partially collapsed workbasket assembly shown in the third stage of collapsing the same; 
           [0021]      FIG. 13  is a rear view of the workbasket assembly shown in a fully collapsed condition; and 
           [0022]      FIG. 14  is a perspective view of a second embodiment of a collapsible workbasket assembly in accordance with the present invention and showing the inclusion of roller bumpers therein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Referring to  FIGS. 1-8  there is shown a workbasket in accordance with the present invention and generally indicated at  10 . Workbasket  10  comprises a base  11  and a collapsible workbasket assembly  12  that are detachably engageable with each other. Base  11  comprises a floor frame  14  and a mast assembly  16  that extend upwardly away therefrom. The mast assembly  16  is adapted to be engaged with a hoist (not shown) to raise and lower workbasket  10  relative to a horizontal surface  100  such as a bottom wall of a tank (not shown). 
         [0024]    Workbasket assembly  12  is shown separated from workbasket  10  in  FIG. 2 . Workbasket assembly  12  comprises a foldable frame made up from four uprights  18 , two base rails  20 , four mid-rails  22 , a stabilizer bar  24 , a front rail  26 , a back rail  28  and two gate rails  30 . As shown in  FIG. 8 , back rail  28  is positioned vertically further away from the bottom end  19  of uprights  18  than is front rail  26 . Furthermore, the back mid-rail  22   b  is positioned further from bottom end  19  than is front mid-rail  22   a.  This difference in relative distances from bottom end  19  enables workbasket assembly  12  to be more easily collapsed than would be the case if all of the rails were at comparable distances from bottom end  19 . 
         [0025]    Each of the rails  20 ,  22 ,  26 ,  28  and  30  is connected to two of the uprights  18 . The connections are made by way of pivot tabs  32 . All of the pivot tabs  32 , except for tabs  32   a  on gate rails  30 , comprise a pair of spaced apart flanges  34  that are welded at one end to one of the rail and are connected at the other end by way of a pivot pin  36  to the associated upright. So, for example, back rail  28  is secured between uprights  18   a,    18   b  ( FIG. 2 ) by pivot tabs  32   b,    32   c.  Pivot pin tab  32   b  is welded onto first end  28   a  of back rail  28  so that it extends upwardly therefrom. Pivot tab  32   b  is pivotally secured to upright  18   a  by pivot pin  36   b.  Pivot tab  32   c  is welded onto second end  28   b  of back rail  28  so that it extends downwardly therefrom. Pivot tab  32   c  is pivotally connected to upright  18   b  by pivot pin  36   c.  Furthermore, pivot tabs  32   b  and  32   c  extend outwardly from back rail  28  substantially parallel to each other. This type of connection arrangement is true of each rail in workbasket assembly  12 . The ends of flanges  34  that are welded are those ends that are secured to the rails. The ends of the flanges  34  that are pivotally secured are those that are pivotally secured to uprights  18  by pivot pins  36 . This connection arrangement permits only a defined range of pivotal motion by the uprights  18  and rails,  20 ,  22 ,  26 ,  28  and  30 . When workbasket assembly  12  is moved in a first direction to collapse the structure, some of the plurality of flanges  34  are brought into contact with some of uprights  18 . For example, back rail  28  can be moved in a direction “D” ( FIG. 2 ). This movement causes uprights  18   a,    18   b  to pivot about pivot pins  36   b,    36   c  and workbasket assembly  12  begins to collapse in the direction “D”. If, however, an attempt was made to move back rail  28  in a direction opposite to direction “D”, then first end  28   a  of back rail  28  would come into abutting contact with upright  18   a  and motion in that direction will cease. This is true of all of the rails in workbasket assembly  12  and, as a consequence, workbasket assembly  12  can only be moved from an expanded condition ( FIG. 2 ) to at least a partially collapsed condition ( FIG. 10 ) in a single direction, i.e., direction “D”. Workbasket assembly  12  can also be moved from that collapsed condition ( FIG. 10 ) to an expanded condition ( FIG. 2 ) in only a single direction, i.e., the opposite direction to “D”. 
         [0026]    A first end of each gate rail  30  is secured to one of uprights  18   a  or  18   b  by pivot tabs  32 . A second end of each gate rail  30  is secured to uprights  18   c  or  18   d  by pivot tabs  32   a.  Pivot tabs  32  each comprise a pair of spaced apart flanges  34  but, instead of a pivot pin  36 , the securement used is a detented ring pin  38  and lanyard  40 . Similarly, as shown in  FIG. 2 , one end of stabilizer bar  24  is secured to mid-rail  22   a  by a pivot tab  32  and a second end of stabilizer bar  24  is secured to upright  18   c  by a pivot tab  32   a  and a detented ring pin  38  and lanyard  40 . Thus, one end of each of gate rails  30  and stabilizer bar  24  may be released from engagement with an upright  18  and pivoted as shown by the arrows in  FIGS. 1 and 8  respectively. 
         [0027]    Gate rails  30  are shown in greater detail in  FIGS. 3 &amp; 4 . Each gate rail  30  comprises a tubular first sleeve  42  and second sleeve  44 . First and second sleeves  42 ,  44  each include a bore  42   a,    44   a  that receives a portion of a bar  46  therein. A compression spring  48  is received within bore  42   a  between a roll pin  50  and bar  46 . The opposite end of bar  46  is secured within bore  44   a  by a second roll pin  52 . First sleeve  42  is also provided with a slot  54 . A cap screw  56  is secured within an aperture  58  in bar  46 . The head of screw  56  extends through slot  54 . First sleeve  42  is slidable along bar  46  as indicated by the arrow in  FIG. 3 . Screw  56  limits the degree of travel of first sleeve  42  along bar  46 . First sleeve  42  is retractable toward second sleeve  44  when gate rail  30  is to be detached from upright  18   c  and is movable toward upright  18   c  when gate rail  30  is to be reconnected thereto. It will be understood by those skilled in the art that a single sleeve may be provided to engage with the bar  46 . In this latter instance, one end of first sleeve  42  would be pivotally and detachably connected to upright  18   c  and a free end of bar  46  could be directed and fixedly secured to upright  18   a,  without departing from the spirit of the present invention. 
         [0028]      FIG. 3 and 5  also illustrate a portion of the pivotal connection between upright  18  and gate rail  30  in greater detail. Flanges  34  of pivot tab  32  is welded onto the exterior surface of second sleeve  44  and a second end of flanges  38  are secured to each other and to upright  18  by pivot pin  36  and a cap screw  60 . This pivotal connection is illustrative of the connection between all pivot tabs  32  and uprights  18  in workbasket assembly  12 . 
         [0029]    Referring to  FIG. 6 , base rails  20  are each provided with a pair of spaced apart captive hex screws  62  that are received through apertures  64  in base rails  20 . 
         [0030]      FIG. 7  shows the base  11 , including floor frame  14  and mast  16 , in greater detail. Mast assembly  16  comprises a base  68  and a mast  70  that extend vertically upwardly from said base  68 . A plurality of connectors  71  are used to secure back rail  28  and mid rail  22  to mast  16 . Base  68  has a plurality of spaced-apart supports  72  and an upstanding lip  74  that together define a cradle for receiving floor frame  14  therein. Apertures  66  are provided in the ends of two of supports  72 . Floor frame  14  has a rim  73  sized to be received within the cradle of base  68 . One or more steel angle and mesh sheets  75  are received within rim  73  to provide a solid surface to support a workman thereon. Workbasket assembly  12  is engaged with floor frame  14  and mast assembly  16 . When workbasket assembly  12  is in an expanded condition (shown in  FIG. 2 ), base rails  20  rest on the ends of supports  72  and hex screws  62  are received within apertures  66  in supports  72 . Uprights  18  of workbasket assembly  12  are positioned outwardly away from the corners of rim  73  of floor frame  14 . While floor frame  14  is shown as two separate sheets  75  that rest on frame  14 , it should be understood that frame  14  and sheet  75  could be hinged and foldable so that they too may be passed through a smaller access port of a tank or any other small confined space. 
         [0031]    Still referring to  FIG. 7 , mast assembly  16  further includes support angles  78 ,  80  at either end of mast  70 . A guide roller assembly  82  is mounted onto support angle  80  and a steel cable  84  wraps around roller assembly  82  and is fed therethrough to motor  86 . Mast assembly  16  is used to connect workbasket  10  to a hoist (not shown) which is then used to raise or lower workbasket  10  relative to a horizontal surface  100  such as the interior bottom wall of a tank. 
         [0032]    In accordance with a specific feature of the present invention, workbasket assembly  12  is movable between an expanded and a collapsed condition as hereinafter described. In the expanded condition (shown in  FIG. 2 ), assembly  12  has a height “A” of around 45 inches, a length “B” of around 37 inches and a width “C” of around 33 inches. 
         [0033]    The procedure for collapsing workbasket assembly  12  is shown in  FIGS. 8-13 . The procedure is described as though the workman is standing in front of front rail  26  facing assembly  12 . Firstly, stabilizer bar  24  is detached from upright  18   c  by removing ring pin  38  from the associated pivot tab  32   a.  Stabilizer bar  24  pivots about pivot pin  360  and hangs freely from mid-rail  22   a.  The workman grasps one of the rails, such as front rail  26 , and gently moves front rail  26  toward the right as indicated by arrow “D” in  FIG. 9 . This movement causes uprights  18   a,    18   b,    18   c  and  18   d  to pivot about pivot pins  36   a,    36   d,  back rail  28  to pivot about pivot pins  36   a,    36   b,    36   c,    36   d,    36   g,    35   j,    36   k  and  36   n.  The motion causes the angle X ( FIG. 8 ) between uprights  18   a - 18   d  and front rail  26 , back rail  28 , mid-rail  22   a  and mid-rail  22   b  to be changed from being substantially at right angles thereto to an angle X′ ( FIG. 9 ) of greater than ninety degrees. The pivoting motion causes workbasket assembly  12  to begin to fold, thereby reducing the overall height thereof. The movement of front rail  26  toward the right is continued until workbasket assembly  12  is collapsed into the shape shown in  FIG. 10 . In  FIG. 10 , workbasket assembly  12  is partially collapsed and has a height “E”. This is the shortest vertical height that assembly  12  can have. In the preferred embodiment of the invention, height “E” is around 6 inches. 
         [0034]      FIG. 11  shows a top view of the partially collapsed workbasket. At this stage, while the total height of the workbasket is height “E”, the width of assembly  12  remains the width “C”, i.e., 33 inches. The overall length of workbasket assembly  12  is length “F” which is around 84 inches. 
         [0035]    The workman then stands workbasket assembly on either one of the two edges “G” or “H”.  FIG. 12  shows workbasket assembly  12  resting on edge “G”. The workman then grasps back rail  28  or upright  18   a  and moves the same in the direction of arrow “I”. This movement causes upright  18   a,  back rail  28 , upright  18   c  and front rail  26  to pivot about pivot pins  36   s,    36   p,    36   i,    36   h,    36   e,    38 ,  36   l,    36   m,    36   c  and  36   d.  There is also motion about the pivot pins that connect the other of bottom rails  20  (not shown) to uprights  18   b,    18   d,  but these pivot pins cannot be seen in  FIG. 12 . The motion of workbasket assembly  12  in the direction of arrow “I” causes workbasket assembly  12  to become smaller than width “C”. The workman continues to move rail  28  in the direction of arrow “I” until workbasket assembly  12  has the appearance shown in  FIG. 13 . This is the fully collapsed condition and in this state, workbasket assembly  12  has a length of 114 inches, a height of 6-7 inches and a width of 6-7 inches. Workbasket assembly  12  can now be slid through a narrow opening, even an opening that is about 8×8 inches in size. 
         [0036]    When the workbasket assembly  12  is in the desired location, it may be unfolded by reversing the above-mentioned steps until assembly  12  is once again in the fully expanded condition ( FIG. 2 ). Assembly  12  is then positioned over floor assembly  14  and fasteners  62  are engaged in supports  72 . Workbasket  10  can then be attached to a hoist (not shown) via mast  70 . When a workman wishes to enter workbasket  10 , they may release either one of gate rails  30 . This is done by removing ring pin  38  from the aperture  39  in the appropriate one of vertical rails  18   c  or  18   d.  This detaches pivot tab  32   a  from the vertical rail  18   c  or  18   d.  The workman then slides first sleeve  42  rearwardly toward second sleeve  44 , thereby effectively reducing the overall length of gate rail  30 . Gate rail  30  is then rotated upwardly away from mid-rail  22  as shown by the arrow in  FIG. 1 . The workman may then step more easily over mid-rail  22  and onto the grate in floor assembly  14 . Gate rail  30  is rotated downwardly and first sleeve  42  is slidably moved away from second sleeve  44  to increase the length of rail  30 . Pivot tab  32   a  is then repositioned proximate aperture  39  and ring pin  38  is inserted through aligned holes in the pivot tab  32   a  and aperture  39 . When the workman wants to exit workbasket  10 , he releases gate rail  30  once again, rotates the same out of the way, steps out of workbasket  10  and reattached gate rail  30  to the appropriate one of vertical rails  18   c,    18   d.    
         [0037]    It should be noted that the pivot tabs  32 ,  32   a  are shaped and arranged on workbasket assembly  12  in such a manner that assembly  12  can only be moved from the expanded condition to the partially collapsed condition by moving front rail  26  in only one single direction. So, for example, in  FIGS. 8 and 9 , front rail  26  of workbasket assembly  12  can only be moved toward the right, i.e., in the direction of arrow “D” in order to collapse the basket. If front rail  26  was moved in the direction opposite to arrow “D” the edges  27 ,  29  of front and back rails  26 ,  28  and edges  23  of mid-rails  22  would hit into uprights  18   a  and  18   c  and stop all movement in that direction. This arrangement simplifies matters for the workman because he doesn&#39;t have to stop and think about how to collapse or expand workbasket assembly  12 . Furthermore, the interference of the edges  27 ,  29  and  23  with uprights  18   a,    18   c  also stops workbasket assembly  12  from collapsing in the direction opposite to arrow “D” when the workman is attaching or detaching stabilizer bar  24 . 
         [0038]      FIG. 14  shows a second embodiment of workbasket assembly in accordance with the present invention and being generally indicated at  112 . Workbasket assembly  112  is substantially identical to workbasket assembly  12  except that each mid-rail  122  includes a tube  190  that is welded thereto. A roller bumper  192  is telescopingly received in tube  190 . Roller bumper  192  comprises a caster  194  which is attached to a hollow adjustment bar  196 . Adjustment bar  196  includes a plurality of holes  198  therein. A cotter pin  202  is selectively insertable through an aperture (not shown) in tube  190  and into any one of the desired holes  198  in adjustment bar  196 . Roller bumper  192  can therefore be extended further outwardly away from workbasket assembly  112  to a greater or a lesser degree, or can be withdrawn substantially into tube  190 , or can be entirely removed from tube  190 . Caster  194  is adapted to engage the interior surface of the side wall of a tank. The caster  194  prevents the workbasket assembly  112  from directly contacting the interior surface of the tank&#39;s side wall and because caster  194  is rotatable, it aids in assisting the workbasket to ride up and down within the interior of the tank. It will be understood that tubes  190  and roller bumpers  192  may be secured to any one of the rails or uprights of workbasket assembly  112  without departing from the spirit of the present invention. It will further be understood that workbasket assembly  112  is collapsible and expandable in the same way as workbasket assembly  12 . 
         [0039]    It will be understood by those skilled in the art that workbasket assembly  12  may be partially collapsed when attached to base  11  but can only be fully collapsed when fully detached from base  11 . 
         [0040]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0041]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.