Abstract:
A reusable mud-sill to replace the conventional wooden-mud-sills and to capture without the use of tools the small-metal-plate conventionally found at the bottom of scaffold legs. Mud-sills are used to interface the bottom ends of scaffold legs, or the like, to the ground and to provide reasonable ground pressure while inhibiting side movement of a leg. The reusable mud-sill captures a small-metal-plate with two fixed opposing side-blocks, a fixed overlapping-retainer, and a sliding overlapping-retainer that may be locked to the reusable mud-sill when the conventional small-metal-plate has been captured. The cooperating, capturing parts are all centrally placed on the top of a flat-plate that is significantly larger than the small-metal-plate.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application 61/137,450 filed Jul. 31, 2008, which is incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The technical field of the present invention is the field of mud-sills. Mud-sills are most often associated with scaffolding. The vertical and diagonal supports of scaffolding react their longitudinal force into the supporting ground. Most often, the ends of the supports are terminated with a screw (or like means for adjusting height) attached to a small-metal-plate. To distribute the force into a reasonable ground pressure, and to conform to 29 CFR 1926.451 (c)(2) and similar state requirements, the small-metal-plate found at the bottom end of scaffold legs is nailed to the top of a wooden board that contacts the ground. The wooden board is called a mud-sill. 
         [0004]    The subject of this invention is an improved, reusable mud-sill that provides enhanced safety and that provides significant cost savings as compared to present wooden board mud-sills. The present invention&#39;s reusable mud-sill is intended to replace the conventional wooden-mud-sills. More particularly, the mud-sill of the present invention is able to capture the small-metal-plate without the use of tools and without the use of a wooden board, and is able to be reused many times. While the present invention is expected to have its major utility in conjunction with scaffolding, the present invention will also have utility with ladders and the like where their ground termination must not shift. The present invention makes use of the small-metal-plate that is most often essentially six inches square and that is conventionally found at the bottom end of scaffold legs. The present invention is also useful with small-metal-plates that are essentially five inches square. 
         [0005]    2. Background Art 
         [0006]      FIG. 1  illustrates the prior-art. Three different linkages between scaffolding (not shown) and wooden-mud-sill  1  are shown on  FIG. 1 . In most cases, scaffold-legs are essentially normal to small-metal-plate  10  as shown in the bottom two sub-figures of  FIG. 1 . In one of those cases, fixed-scaffold-leg  14  is affixed directly to small-metal-plate  10  with a height-adjuster  18  being provided or, in the other case, fixed-scaffold-leg  14  is connected to small-metal-plate  10  by means of fixed-leg-coupler  12  with height-adjuster  18  being provided. The latter scheme of attachment of a fixed-scaffold-leg  14  to small-metal-plate  10  is also seen on  FIGS. 2 &amp; 3 . A variation, seen on the upper sub-figure of  FIG. 1 , uses a pivotable-scaffold-leg  15  that uses cross-piece  16  within bushing  17  to provide for other than normal attachment to small-metal-plate  10 . The latter scheme of attachment of pivotable-scaffold-leg  15  to small-metal-plate  10  is also seen on  FIG. 4 . 
         [0007]    In each type of attaching a scaffold-leg to small-metal-plate  10 , the prior art includes nailing small-metal-plate  10  to wooden-mud-sill  1 . Scaffold-legs are usually threaded to facilitate manually adjusting the scaffold-leg&#39;s height using height-adjuster  18 . Information similar to that shown on  FIG. 1  may be seen within  FIG. 7  of U.S. Pat. No. 5,156,235. 
         [0008]    A significant limitation of the prior-art involves the wooden boards that are used as mud-sills. Firstly, to be effective, the wooden boards must be fairly thick and long. Hence, the necessarily heavy wooden boards are awkward to transport and to wrestle into place. Secondly, the contact of the wooden boards with the ground causes than to absorb moisture, which increases their weight and which hastens their rotting. Thirdly, the tendency of the boards to rot and to be mud covered reduces the likelihood of being reused, which adversely impacts the cost of using wooden boards. Fourthly, having to nail the small-metal-plates to the wooden boards, and the accompanying need to remove the nails when moving the attendant scaffold, results in a significant labor and material cost. 
         [0009]    Among the objectives of the present invention is the objective to overcome the listed limitations of the use of wooden board mud-sills. More specifically: the present invention is easy to transport and to place into position. It requires negligible effort, and no tools, to have the present invention capture small-metal-plates. Additionally, the present invention is expected to last for many years resulting in its expected amortized cost to be less than the alternatives and the use of the present invention eliminates the need to have a stock of nails and hammers, effecting further value. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The preferred embodiment of the present invention is seen on the drawings as reusable mud-sill  30 . The preferred embodiment is made of steel although other materials would also be suitable. The invention captures a standard, six inch by six inch small-metal-plate  10 , found at the bottom of scaffolding, by inserting the small-metal-plate between side-blocks  22  and into front-overlapping-retainer  24  with the moveable-rear-overlapping-retainer  32  slid as far from the center of mud-sill  30  as allowed by the retaining-pins that are captive in retaining-pin&#39;s grooves  36 . The moveable-rear-overlapping-retainer  32  is then slid towards the center so that the small-metal-plate is captured. Locking-lever  38  is rotated into a mating groove, thus locking the small-metal-plate in place. 
         [0011]    Optionally, the reusable mud-sill  30  may have its resistance to side movement enhanced by inserting spikes  40  into spike-holes  42  that are provided in the corners of the reusable mud-sill  30 . The spikes  40  are easily retracted with minimal damage when it is time to move mud-sill  30 . 
         [0012]    When it is time to move the associated scaffolding, locking-lever  38  is rotated out of its groove, moveable-rear-overlapping-retainer  32  is slid away, and the small-metal-plate  10  is free. The reusable mud-sill  30  may now be moved to a new location or stored for future use. All of this is accomplished without the use of tools. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]      FIG. 1  shows the prior art of nailing small-metal-plates to a wooden board mud-sill. Three conventional attachments of scaffold legs to small-metal-plates are shown. 
           [0014]      FIG. 2  shows the preferred embodiment of the present invention in an un-locked state with a small-metal-plate in the process of being captured. 
           [0015]      FIG. 3  shows the preferred embodiment of the present invention in a locked state with a small-metal-plate captured by the present invention. 
           [0016]      FIG. 4  shows the preferred embodiment of the present invention in a locked state with a small-metal-plate that has a pivotable-scaffold-leg. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIGS. 2 and 3  advantageously show the preferred embodiment of the present invention. Reusable mud-sill  30  is made of steel and has permanently affixed to it side-blocks  22  and front-overlapping-retainer  24 . Since the reusable mud-sill  30  will be in contact with the earth, it is anticipated that it might advantageously be composed of marine-brass, stainless-steel, or of a strong plastic. The latter materials are expected to be more expensive than steel, but are also expected to be much more resistant to corrosion than is steel. It is advantageous to paint all of the present invention with a corrosion resistant paint. 
         [0018]    Side-blocks  22  are spaced apart slightly more than six inches so as to accommodate a standard small-metal-plate  10  that is six inches square. Side-blocks  22  are essentially parallel to each other and front-overlapping-retainer  24  has its opening essentially normal to the side-blocks  22 . The inside height of front-overlapping-retainer  24  is slightly more than the expected thickness of a standard small-metal-plate  10 . The typical small-metal-plate  10  has a centrally located, fixed-leg-coupler  12  that is perpendicular to the small-metal-plate  10  and typically fixed-leg-coupler  12  contains cross-pin-orifice  13  used with a cross-pin to retain the bottom of a scaffold leg, or the like.  FIG. 4  shows an alternative coupler associated with small-metal-plate  10 . 
         [0019]    The permanent affixing of side-blocks  22  and front-overlapping-retainer  24  to the sill may be effected by welding, bolting, or other means such that the area between side-blocks  22  and front-overlapping-retainer  24  is kept clear to receive small-metal-plate  10 . Welding is the preferred method of affixing side-blocks  22  and front-overlapping-retainer  24  to reusable mud-sill  30 . An embodiment could be effected by casting or molding a single assembly that could include side-blocks  22 , front-overlapping-retainer  24 , and reusable mud-sill  30 . 
         [0020]    However constructed, the assembly consisting of side-blocks  22 , front-overlapping-retainer  24 , and reusable mud-sill  30  is augmented to accommodate moveable-rear-overlapping-retainer  32 . The augmentation includes cutting (or otherwise effecting) a groove within reusable mud-sill  30  that will align with locking-lever&#39;s groove  39  when moveable-rear-overlapping-retainer  32  captures small-metal-plate  10  and that will receive locking-lever  38  when locking-lever  38  is rotated into a locking position. Optionally, one may augment the assembly consisting of side-blocks  22 , front-overlapping-retainer  24 , and reusable mud-sill  30  by providing spike-holes  42  in the corners of reusable mud-sill  30 . Additional augmentation of the assembly consisting of side-blocks  22 , front-overlapping-retainer  24 , and reusable mud-sill  30  involves providing retaining-pins as described next. 
         [0021]    Side-blocks  22  and front-overlapping-retainer  24  will retain small-metal-plate  10  in three horizontal directions, which includes sideways and upwards. Moveable-rear-overlapping-retainer  32  is used to affix small-metal-plate  10  in the fourth horizontal direction, and in the vertical direction, on a releasable basis. Moveable-rear-overlapping-retainer  32  and the mud-sill contain several cooperating parts. To effect the ability of the invention selectively to affix and to release small-metal-plate  10 , moveable-rear-overlapping-retainer  32  is able captively to slide towards or away from the center of reusable mud-sill  30 . The captive sliding capability is effected by extending two retaining-pins into retaining-pin&#39;s grooves  36  that are on each side of moveable-rear-overlapping-retainer  32  and that are parallel to each other. The above-surface ends of the retaining-pins are visible on the drawings as retaining-pin&#39;s heads  35 . It is not possible to show the retaining-pins themselves as they are within retaining-pin&#39;s groove  36 . The retaining-pins may be effected with bolts screwed down into the sill or with metal dowels extending upward through the sill. However effected, the retaining-pins have a width less than the width of retaining-pin&#39;s groove  36  and are surmounted with retaining-pin&#39;s head  35  that prevents moveable-rear-overlapping-retainer  32  from being detached from the mud-sill. 
         [0022]    Alternatively, the preferred embodiment of the present invention may be described as an essentially flat-plate that is significantly larger than the small-metal-plate upon the top of which side-blocks  22 , front-overlapping-retainer  24 , and moveable-rear-overlapping-retainer  32  are placed. In the preferred embodiment, the essentially flat-plate is about  12  inches square and this size is included in what is meant by significantly larger than the small-metal-plate. 
         [0023]    The side-blocks  22  are expected to be essentially parallel to each other, separated by slightly more than six inches, and having a height of at least twice the expected thickness of the small-metal-plate. Front-overlapping-retainer  24  is expected to be essentially normal to side-blocks  22  with an opening that faces towards the center of the flat-plate and that is slightly greater than the expected thickness of the conventional small-metal-plate. The moveable-rear-overlapping-retainer  32  is able captively to slide on the flat plate, has an opening that faces the opening of the front-overlapping-retainer  24 , is essentially normal to side-blocks  22 , and that is slightly greater than the expected thickness of the conventional small-metal-plate. 
         [0024]    A rotatable locking-lever  38  is mounted on moveable-rear-overlapping-retainer  32  such that locking-lever  38  may be rotated into locking-lever&#39;s groove  39  that is within the flat-plate when the small-metal-plate is within and captured by moveable-rear-overlapping-retainer  32 . 
         [0025]    It is apparent that the flat-plate and its surmounted components may be made of steel and numerous other materials. It is also apparent that the shown, described and preferred side-blocks  22 , front-overlapping-retainer  24 , moveable-rear-overlapping-retainer  32  and its way of being captive and of being able to be locked, may be effected by other schemes that will apparent to one skilled in the art. 
         [0026]    To use the present invention, one places reusable mud-sill  30  directly below a leg of a scaffold having a small-metal-plate  10 , rotates locking-lever  38  out of engagement with locking-lever&#39;s groove  39  (and thus out of engagement with the cooperating groove in reusable mud-sill  30  that is not possible to be seen), slides moveable-rear-overlapping-retainer  32  away from the center of reusable mud-sill  30 , places small-metal-plate  10  onto reusable mud-sill  30 , slides an edge of small-metal-plate  10  under the overhang of front-overlapping-retainer  24 , slides moveable-rear-overlapping-retainer  32  so that it overlaps small-metal-plate  10 , and rotates locking-lever  38  into locking-lever&#39;s groove  39 , thus capturing small-metal-plate  10 . These steps are reversed when it is time to move the associated scaffolding and the reusable mud-sills  30 . Optionally, one may place spikes  40  within spike-holes  42  so as to enhance the resistance of reusable mud-sill  30  to motion side-ways. Such spikes need not be driven flush with reusable mud-sill  30 . 
         [0027]      FIG. 2  shows the present invention with moveable-rear-overlapping-retainer  32  unlocked and moved towards the outer edge of the mud-sill so that reusable mud-sill  30  can receive small-metal-plate  10 .  FIG. 3  shows the present invention with moveable-rear-overlapping-retainer  32  moved away from the edge of the mud-sill so as to capture small-metal-plate  10  and  FIG. 3  shows locking-lever  38  rotated about pivot-pin-support  34  using pivot-pin  37  to engage locking-lever&#39;s groove  39  and a groove below locking-lever&#39;s groove  39  that is in the mud-sill.  FIG. 3  also shows that moveable-rear-overlapping-retainer  32  is kept from leaving the mud-sill by retaining-pin&#39;s heads  35  that are larger than the width of retaining-pin&#39;s groove  36 . 
         [0028]    The information in  FIG. 4  differs from that in  FIG. 3  only in that  FIG. 4  shows the use of an optional, but conventional, way that small-metal-plate  10  is coupled to a leg of a scaffold. In  FIG. 4 , pivotable-scaffold-leg  15  has an upward section threaded and has its height adjustable by height-adjuster  18 . Pivotable-scaffold-leg  15  is able to be pivoted from being perpendicular to small-metal-plate  10  by pivot-angle  19 . That feature is effected by pivotable-scaffold-leg  15  having a lower cross-piece  16  normal to pivotable-scaffold-leg  15  that is captive within bushings  17 . It is to be apparent that variations exist for effecting the coupling of the leg of a scaffold with small-metal-plate  10  and that reusable mud-sill  30  is able to capture the variations. Small-metal-plates  10  that are five inches square have been occasionally experienced and it has been found that the reusable mud-sill  30  described herein captures the smaller small-metal-plate  10  in a satisfactory manner.