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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates in general to work ladders, and in particular to a ladder having a working platform for supporting a worker over a freshly poured concrete floor.  
         [0003]     2. Description of Prior Developments  
         [0004]     In new building construction a worker typically works a freshly poured concrete basement floor by raking, screeding, vibrating and otherwise leveling and smoothing the floor with various powered and manual tools. A problem arises when the worker nears completion of working the floor, as the worker must somehow complete the basement floor smoothing operation without stepping on the concrete which has just been worked.  
         [0005]     One solution has been to suspend a common work ladder from a board extending across and above a corner between two basement walls. A worker then climbs up on a lower rung of the ladder, and finishes working the area beneath the ladder. Once done, the worker climbs up the ladder to ground level leaving a completely worked floor behind.  
         [0006]     It can be appreciated that this prior technique can be awkward for a worker and even potentially dangerous as the worker hangs on the ladder with one hand and works the concrete floor with the other hand. Moreover, because the height of basement walls can vary, a worker may need several ladders of different lengths to match the height of the wall adjacent the floor being worked.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention has been developed to overcome the drawbacks noted above and therefore has as an object the provision of a ladder that may be safely and securely mounted and suspended over and adjacent to a freshly poured concrete floor. A height adjustment may be provided to adjust the height of the ladder above the floor so as to allow a worker to easily work the area around and beneath the ladder.  
         [0008]     A working platform is provided on the bottom of the ladder to support a worker above the floor with a clearance sufficient to allow the worker to easily access and work the floor around and beneath the platform. The platform may be pivoted to the bottom of the ladder to provide a compact assembly for transport or storage.  
         [0009]     The forementioned objects, features and advantages of the invention will, in part, be pointed out with particularity, and will, in part, become obvious from the following more detailed description of the invention, taken in conjunction with the accompanying drawings, which form an integral part thereof. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     In the drawings;  
         [0011]      FIG. 1  is a top perspective view of a construction ladder used in accordance with the prior art;  
         [0012]      FIG. 2  is a top perspective view of a ladder constructed in accordance with the present invention;  
         [0013]      FIG. 3  is a partial upper left side elevation view of the ladder of  FIG. 2 ;  
         [0014]      FIG. 4  is a sectional view through section lines  4 - 4  of  FIG. 2 ;  
         [0015]      FIG. 5  is a partial lower left side elevation view of the ladder of  FIG. 2 ;  
         [0016]      FIG. 6  is a sectional view through section line  6 - 6  of  FIG. 2 ; and  
         [0017]      FIG. 7  is a view similar to  FIG. 5 , showing the platform assembly disposed in a storage or compact transportable position. 
     
    
       [0018]     In the various Figures of the drawings, like reference numerals designate like or similar parts.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     A brief review of a conventional concrete floor working ladder arrangement will be helpful in appreciating the benefits of the present invention. As seen in  FIG. 1 , a worker, completing the finishing of a newly poured concrete basement floor  10 , has placed a board  12  across a corner  14  formed between two basement walls  16  and  18 . The board  12  is inserted beneath one of the upper rungs  20  on a common work ladder  22 .  
         [0020]     When the worker has finished working the entire floor, except for the area  24  beneath the ladder  22 , the worker climbs up on the lower rung and finishes working the area  24  while being suspended on the ladder  22 . As noted above, this is awkward and potentially dangerous.  
         [0021]     As seen in  FIG. 2  the present invention avoids the drawbacks of the ladder of  FIG. 1  by providing a rigid, secure ladder assembly  30  for working a newly poured concrete floor  10 . Ladder assembly  30  includes a ladder  32  having a pair of side rails  34  and  36 . A plurality of vertically spaced rungs  38  is secured to the side rails  34  and  36  in a known fashion. While the side rails  34  and  36  and rungs  38  are preferably formed of aluminum, any suitable material such as wood or composite materials may be used.  
         [0022]     The ladder assembly  30  includes a hanger assembly  40  mounted to the top portions of the side rails  34  and  36 . Hanger assembly  40  includes a pair of inverted U-shaped hanger hooks  42  adapted to hook over and around the top edges  44  of concrete basement walls  16  and  18 . Hooks  42  may be formed of aluminum or steel or any other strong material.  
         [0023]     The front face  46  of each hanger hook  42  is connected to a channel-shaped sleeve  48  such as by welding, bolts, or any other suitable fastening technique. Each sleeve  48  includes a pair of arms or side walls extending from a central base so as to embraces three outer sides of each side rail with a close sliding fit. The sleeves  48  are adjustably fastened and pinned to their respective side rails  34  and  36  with removable rods  50 .  
         [0024]     Each rod  50  is insertable through clearance holes  52  ( FIG. 3 ) formed through the base of each sleeve  48 . The holes  52  are aligned with matching holes  54  ( FIG. 3 ) formed through each side rail  34  and  36  to allow the rods  50  to pass through the sleeves and side rails. A cotter pin  56  or other fastener may be used to anchor the rods  50  to the sleeves and sidewalls.  
         [0025]     The hanger assembly  40  can be adjusted up or down along the side rails by removing the rods  50  and realigning the holes  52  in the sleeve with a desired pair of holes  54  in the side rails. The rods  50  are then reinserted and fastened in place with cotter pins  56 . In this manner, the bottom portion of the ladder assembly, including the side rails and lower rungs may be adjusted and suspended at a desired selected distance above the floor  10  so as to allow a worker to freely work the area under the ladder.  
         [0026]     In order to provide room between the rear face of the side rails and the wall  16 , a pair of rearwardly projecting spacer bars or stand-offs  60  is fixed at vertically spaced distances along each side rail. The spacing from wall  16  provides room for a worker to securely grasp the front, side and rear surfaces of each side rail when climbing up and down on the ladder assembly  30  and to allow a worker to step safely and fully on each rung  38 . The spacer bars may be formed of aluminum and bolted, welding or otherwise attached to the side rails  34  and  36 .  
         [0027]     A support platform assembly  70  is carried on the bottom portion of the ladder assembly  30 . Platform assembly  70  includes a planar worker platform  72  extending substantially perpendicularly outwardly from the side rails  34  and  36 . The worker platform  72  is preferably about  17  inches wide and projects outwardly about  18  inches from the side rails to allow a worker to freely stand on the worker platform without the need to grasp the side rails.  
         [0028]     The worker platform  72  may be formed of a sheet of aluminum, steel or even plywood. The platform  72  may be reinforced with angle bars  74  secured under its entire outer periphery as well as on its central underside as shown in  FIG. 4 . The platform  72  is secured to the bottom of each side rail with a U-shaped yoke  76 . Each yoke  76  extends around the sides and rear face of each side rail  34  and  36 , as seen in  FIG. 2 .  
         [0029]     The yokes  76  may be formed of aluminum and welded to the upper rear surface of platform  72 . Each yoke is pivotally connected to the bottom portion of each respective side rail  34  and  36  by a pivot pin  80 . As seen in  FIG. 6 , each pivot pin  80  extends through aligned channels  82  formed in each leg  84  of each yoke  76 . A similar channel  86  is formed through each side rail and coaxially aligned with channels  82 .  
         [0030]     In  FIG. 6 , the side rail  36  is shown having an I-shaped cross section, as is common on aluminum side rails. A pair of metal support plates  88  is welded or otherwise secured to opposite sides of the central web  90  of each side rail  34  and  36  to provide added strength and weight bearing capacity to the pivoted or pinned connection between the side rails and platform assembly  70 .  
         [0031]     A tubular brass bushing  92  may be press fit through aligned channels  82  and  86  in the yoke and side rails, as well as channels  96  formed through the support plates  88 . Bushing  92  adds strength and support to the pinned connection, and reduces wear between moving surfaces.  
         [0032]     In order to limit the downward rotation of the platform assembly  70  around the ends of the side rails as indicated by arrow  98  in  FIG. 5 , a stop block  100 , in the form of, for example, an aluminum block is welded or otherwise securely fixed adjacent to the bottom rear face of each side rail. As seen in  FIG. 5 , the bottom face  102  of stop block  100  is fixed at a position on side rail  36  so as to abut the upper surface of the central base  104  of yoke  76  and so as to securely hold the worker platform  72  at a position extending substantially perpendicularly to the side rails.  
         [0033]     Rotation of the worker platform  72  in the opposite or upward direction, as represented by arrow  104  in  FIG. 5 , is substantially unrestricted until the worker platform rests on or adjacent to the side rails, as shown in  FIG. 7 . In this position, the worker platform  72  is aligned substantially parallel to the side rails so as to form a compact assembly suitable for easy transport and storage.  
         [0034]     In use, a worker aligns the hanger assembly  40  over a wall and extends or pivots the support platform assembly  70  outwardly as shown in  FIG. 2 . The worker then works or finishes the surface of the floor  10  until all of the floor  10  is worked, except for the area under the platform assembly  70 .  
         [0035]     The platform assembly  70  is typically suspended or cantilevered over the floor  10  by several inches up to a foot or more through vertical adjustment of the sleeves  48  which carry the hanger hooks  42 . This spacing allows a worker to step on worker platform  72  and finish working the area beneath and around the platform assembly  70 , i.e. within reach by hand or tool. Once a worker climbs or steps up on the worker platform  72 , the worker can work the area around the platform assembly with both hands, as the worker platform is dimensional to provide adequate area for the worker to stand and move about on the worker platform without the need for grasping the side rails.  
         [0036]     There has been disclosed heretofore the best embodiment of the invention presently contemplated. However, it is to be understood that the various changes and modifications may be made thereto without departing from the spirit of the invention. For example, while the side rail have been shown as one piece rigid members, the side rails may be provided as collapsible multi-piece members that fold up in an accordion style for space saving, as is known in the industry.

Summary:
A ladder is provided with a pair of vertically adjustable hangers for suspending the ladder from a wall or other structure. A working platform is pivotally connected to the bottom of the ladder to support and suspend a worker over a freshly poured concrete floor in such a manner that the worker may work the concrete beneath the platform without stepping on the freshly poured concrete floor.