Patent Abstract:
A protective ladder cap for fitting over the end of a rail of a ladder is provided. The cap has an open end for fitting over the rail and a closed end. The ladder cap has tapered internal ribs for engaging the end of a side rail of a ladder. The ladder caps prevent the ladder side rails from damaging the surface upon which the ladder leans when in use.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates to ladders and, more particularly, to protective caps that secure over the ends of the rails of a ladder to protect the surface upon which the ladder leans when in use. 
     BACKGROUND OF THE INVENTION 
     Ladders have been used for decades by homeowners and commercial entities. Without a doubt, ladders provide great utility to those that use them. In decades past, most ladders were made of wood, but that has changed. Most ladders today are made of aluminum or fiberglass. Aluminum or fiberglass is desirable because the materials are lightweight and durable. Nonetheless, the rails that form the sides of the ladder have a tendency to cause damage to the surface upon which they are leaning. Further, hard plastic end pieces are often times used to protect the ends of the rails and are prone to damage the surface upon which they rest. It is not uncommon for the ladders to leave scratches and marks on, for example, vinyl siding. 
     Industry recognized this problem and, for a number of years, has offered protective caps that fit over the ends of the ladder rails. The caps are typically made from a pliable plastic. The caps serve to protect the surface upon which the ladder leans. 
     A problem, however, not addressed by the prior art is that ladder rails are not all sized the same. Thus, a protective cap designed to fit on one ladder rail will not fit on all ladder rails. If a user attempts to place a protective cap that is larger than the ladder rail cross-section, the cap will not fit securely on the ladder and can easily fall off the ladder rail. If a user attempts to place a protective cap on the ladder rail that is too small, it may not fit at all, or, if forced over the ladder rail, it may split after some time or during use. Further, the user often times does not know the size of the ladder rail. It is therefore much easier to buy a product that is adapted to fit over a broader range of varying sized side rails 
     SUMMARY OF THE INVENTION 
     This invention is directed to a protective ladder cap for fitting over the end of a rail of a ladder. The cap has an open end for fitting over the rail and a closed end. The cap has at least one elongated internal rib that tapers from a lower rib height closer to the open end than the closed end to a higher rib height closer to the closed end than the open end. In the preferred embodiment, the cap includes a plurality of internal ribs. The internal ribs also preferably comprise an indent portion adjacent the closed end of the rail to secure the cap on the ladder rail. 
     In the preferred embodiment, the protective ladder cap has two wide internal faces and two narrow internal faces. The internal ribs are on at least one of the wide internal faces, and preferably both. In an even more preferred embodiment, the internal ribs are on the narrow faces as well. 
     Because the internal ribs taper from a lower height to a higher height, the ladder cap is adapted to receive ladder rails of varying cross-section. Further, the tapered ribs ensure that the ladder cap is secured to the ladder, thus minimizing the ability of the ladder cap to fall off of the ladder rail. Because the ladder cap of the present invention is able to securely fit on ladder rails having varying cross-sections, consumers purchasing ladder caps are not required to know the cross-section size of their ladder rails. Thus, the ladder cap of the present invention also makes it much easier for consumers to purchase a ladder cap that fits snugly on the consumer&#39;s ladder. 
     These and other aspects of the invention are described more fully below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the ladder cap of the present invention shown as attached to the ends of the side rails of the ladder; 
     FIG. 2 is a perspective view of the ladder cap of the present invention; 
     FIG. 3 is a cross-sectional view of the ladder cap, taken along the plane parallel to the side face of the ladder cap and represented by section line  3 — 3  in FIG. 5; 
     FIG. 4 is a cross-sectional view of the ladder cap, taken along the plane parallel to the side face of the ladder cap and represented by section line  4 — 4  in FIG. 5; and 
     FIG. 5 is a cross-sectional view of the ladder cap, looking directly into the ladder cap and taken along the plane represented by section line  5 — 5  in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, the present invention is directed to a protective ladder cap  10  that is adapted to fit on a ladder  12 . The ladder, as is well known, typically includes two side rails  14  and a plurality of rungs  16  (only one shown) that are spaced apart to provide steps for the user. The ladder cap  10  is sized to fit over the ends of the side rails  14  to protect the surface upon which the ladder is resting. 
     As shown in FIG. 2, the protective ladder cap  10  comprises a cap  18  that has an open end  20  and a closed end  22 . The open end  20  is sized to fit over the end of the side rails. The opening is defined by the length from point  24  to point  26 , which is preferably about 3.5 inches and the length from point  28  to point  30 , which is preferably about 1.25 inches. The dimensions are sized to allow the ladder cap  10  to be easily slid over the ends of the side rails  14 . Referring to FIGS. 3 and 4, the inner surface  32  of the closed end  22  typically abuts against the ends of the side rails when the ladder cap is pushed onto the ladder side rails  14 . The cap  18  includes two wide sidewalls  34  and two narrow sidewalls  36 , which together with the top or closed end  22  form the cap  18 . 
     As shown best in FIG. 3, the ladder cap  10  includes two opposed side detents  38  that protrude inwardly to engage the side rails. From the detents  38 , the two wide sidewalls extend outwardly to the closed end  22  at approximately six degrees and the two narrow sidewalls extend outwardly to the closed end  22  at approximately fourteen degrees (i.e., both walls are angled outwardly slightly). The total height of the ladder cap  10  from the open end  20  to the closed end  22  is approximately 5.5 inches. The total height from the open end  20  to the middle of the detents  38  is approximately 2 inches. 
     The two wide sidewalls  34  of the ladder cap  10  have internal wide faces  40  and the two narrow sidewalls have internal narrow faces  42 . In the preferred embodiment, the ladder cap  10  includes a plurality of elongated internal wide face ribs  43  on the internal wide faces  40 , as shown in FIGS. 3 and 5. Referring to FIG. 4, the length of each wide face rib  43  is approximately 3 inches, and the height tapers from point  44  to a height of approximately 0.094 inches at point  46 . The taper from point  44  to point  48  is less than the taper from point  48  to point  50 . At point  48 , the height of the rib is approximately 0.219 inches and at point  50  the height of the rib is approximately 0.344 inches. The height at point  51  is approximately 0.438 inches. The internal wide ribs  43  preferably include a height of at least 0.250 inches and the rib is preferably tapered from a lower height of around zero inches to the maximum height, as shown in FIG. 4 at point  51 . Nonetheless, it is appreciated that the lower height could be more than zero. The lower the height, however, the easier to facilitate a smooth engagement by the end of the ladder rail onto the surface of the internal rib. It should also be understood that the terms “narrow” and “wide” as used herein are used simply as descriptive terms to distinguish between the various sides; the terms should not be construed to be limited to a particular dimension or size. 
     The wide face ribs  43  also include an indent portion  52  in the preferred embodiment. The indent portion together with the closed end  22  forms a u-shaped channel. The depth from point  51  to the bottom  54  of the indent portion  52  is approximately 0.344 inches. The width of each wide face rib  43  is approximately 0.100 inches and the distance between each rib is approximately 0.210 inches. As shown in FIG. 5, wide face ribs  43  extend inwardly beyond the open end  20  such that when the ladder cap  10  is slid on the end of a side rail  14  through open end  20 , the side rail  14  engages the tapered internal wide face ribs  43 . If the ladder cap  10  is pushed onto the side rail  14  sufficiently, the side rail lodges into the indent portion  52 , further holding the ladder cap  10  on the side rail. 
     In the preferred embodiment, the ladder cap  10  also has narrow face ribs  60  on the internal narrow faces  42 , as shown in FIGS. 3 and 5. The narrow face ribs  60  are approximately the same length as the wide face ribs  43 . The rib height tapers from point  62  to a height of approximately 0.438 inches at point  64  to a height of approximately 0.750 inches at point  66 . The width of each narrow face rib  43  is approximately 0.100 inches and the distance between each rib is approximately 0.210 inches. 
     It should be understood that the dimensions are only illustrative. One skilled in the art can readily appreciate how to alter the dimensions provided without departing from the spirit and scope of the invention. The same is true with respect to the number of internal ribs. In fact, the present invention would work, although not preferably, with only one thicker internal rib that engages the side rail when it is inserted into the ladder cap  10 . Also, the product will perform well with ribs on only the internal wide faces  40  and will work adequately if the ribs are located only on the side faces  42 . By placing ribs on opposed faces, the ladder cap  10  slides over the side rail  14  more evenly and increases the surface area of frictional engagement. In the preferred embodiment, the ladder cap  10  includes at least 5 internal wide face ribs on each wide face  40  and at least two narrow face ribs. 
     In use, the ladder cap  10  is slid over the end of a side rail  14  through open end  20 . The side rail  14  engages the internal ribs  43  and  60 . To the extent the ladder cap  10  is slid over a side rail  14  all the way, the side rail  14  should become lodged in not only the detents  38  but also the unshaped channel formed by the indent portions  52  and the closed end  22 , thus further securing the ladder cap  10  to the side rail  14 . The wide sides  34  and the narrow sides  36  that extend upwardly beyond the detents  38  to form the closed end  22  are approximately 0.250 inches thick. 
     The ladder cap is preferably made out of a PVC plastic that is a dielectric material. In the preferred embodiment, the material is plastisol. 
     While a preferred protective ladder cap has been described in detail, various modifications, alterations, and changes may be made without departing from the spirit and scope of the ladder cap according to the present invention as defined in the appended claims.

Technology Classification (CPC): 4