Abstract:
The present invention provides an extension ladder leveling apparatus and a method of constructing and using a leveling extension ladder. Inward facing leveling means are used to minimized accidents and to facilitate rapid leveling of the extension ladder

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates generally to ladder levelers and more specifically to an improved apparatus for leveling an extension ladder and a method of converting an extension ladder into a leveling ladder.  
         [0002]     Extension ladders that have a top section which slides relative to a bottom section are well known. These ladders are generally formed from extruded aluminum and have side-rails made with channel sections that provide interlocking engagement between the top and bottom ladder sections. Such interlock arrangement usually extends the entire length of the extension ladder. During the course of using an extension ladder, the need often arises to employ the extension ladder on a sloping or uneven surface. For example, when leaning the ladder against the outside of a house, the ground is rarely level. Typically, a block or stack of blocks is placed on the ground and beneath one, or both, of the ladder legs in order to compensate for the different elevation of the ground and keep the extension ladder stable. Identical problems are also encountered in many other instances in which an extension ladder is used on an uneven or inclined surface.  
         [0003]     As can be readily appreciated, the use of blocks and the like under a ladder leads to unsafe conditions and is often the cause of serious injury, particularly since it is not uncommon for bricks, pieces of wood and other makeshift items to be employed as leveling devices. Consequently, a need exists for a ladder which is capable of standing uprightly on uneven or inclined surfaces. It is the primary goal of the present invention to meet that need.  
         [0004]     Previous attempts to provide for the leveling of ladders include: 
        U.S. Pat. No. 6,729,440, issued to Bailey, discloses a step ladder for uneven surfaces, having a mechanism fixed to bottom end of each of the four legs for locking each adjustable leg at preset height and including holes evenly spaced out along each leg with bottom mounted pads that are non-skid surfaces. The locking means is a spring-loaded pin located on the outside of each leg.     U.S. Pat. No. 5,497,850, issued to Patterson, discloses an apparatus for leveling a ladder on uneven surfaces comprised of legs for fitting into the hollow side rails that are fastened through support holes using bolts.     U.S. Pat. No. 5,273,133, issued to Thocher, discloses a ladder leveler. The invention consists of a mechanical gear system and extension member. Upon manually rotating the gear mechanism, the side member will extend or retract according to the direction of the rotation. A means for locking the gear system in place is provided.     U.S. Pat. No. 5,232,067, issued to Griffith, discloses a stile extending attachment for a ladder. The invention consists of an attachment device for use on a ladder having hollow rungs and two side stile members. A long bolt is inserted through two of the hollow rungs and extends from one side stile through to the other and through the attachment device. The attachment device is releasably fastened by a nut and washer at each of the through bolts, thereby allowing the adjustment of the length of one of the two side stile members of the ladder.     U.S. Pat. No. 5,107,958, issued to Johnson, discloses a ladder leveler. The invention consists of a pair of leg extensions that are releasably affixed to the end of the side rails of the ladder. The extensions have a tightening bolt and a tension spring to secure the extension at a desired height. The extensions shown, fit over the end of the side rails and can be affixed thereto with screws or the like.     U.S. Pat. No. 4,091,893, issued to Neal, discloses a ladder with adjustable legs for use on uneven surfaces.     U.S. Pat. No. 3,948,352, issued to Larson, discloses an extension ladder formed of interlocked top and bottom sections having ladder leveler means comprising a pair of sleeve members that slideably encompass the lower end of the bottom section side-rails. A short flange on each sleeve member is captivated by a guide member carried on the inside of each lower side-rail permitting the sleeve members to be securely retained in operative position on the bottom of the ladder without interference with the free sliding of the ladder top section along the bottom section. The secure retaining is accomplished by a spring-biased pin.     U.S. Pat. No. 2,936,849, issued to Larson, discloses a ladder with adjustable legs for use on uneven surfaces.        
 
         [0013]     While these patents and other previous methods have attempted to solve the problem of leveling ladders, none have employed a kit that utilizes the bottom rung and pivot feet of an existing extension ladder in order to form a leveling extension ladder from an existing extension ladder. Additionally, none have employed inward facing spring loaded pull pin assemblies for quick leveling and reduced footprint.  
         [0014]     Therefore, a need exists for an improved apparatus and method for leveling extension ladders.  
         [0015]     The foregoing patent and other information reflect the state of the art of which the inventor is aware and are tendered with a view toward discharging the inventor&#39;s acknowledged duty of candor in disclosing information that may be pertinent to the patentability of the present invention. It is respectfully stipulated, however, that the foregoing patent and other information do not teach or render obvious, singly or when considered in combination, the inventor&#39;s claimed invention.  
       BRIEF SUMMARY OF THE INVENTION  
       [0016]     The present invention provides an apparatus and method of constructing a leveling extension ladder whereby the extension ladder leveling apparatus is comprised of a left rectangular tube assembly, a right rectangular tube assembly, a left extension leg assembly, a right extension leg assembly and a rung assembly. The right extension leg assembly slides into the right rectangular tube assembly and is releasably secured by a pin through a hole in the inward side of the right rectangular tube assembly to an internal slot within the right extension leg assembly. The left extension leg assembly slides into the left rectangular tube assembly and is releasably secured by a pin through a hole in the inward side of the left rectangular tube assembly to an internal slot within the left extension leg assembly. The rung in the rung assembly originates from the bottom rung of an existing extension ladder, is removed from the existing ladder and is shortened prior to becoming part of the rung assembly. The rung assembly is permanently affixed to the two rectangular tube assemblies so that the left rectangular tube assembly and the right rectangular tube assembly are parallel to each other, with the left means for adjusting the leg length of the left extension leg facing the right means for adjusting the leg length of the right extension leg. The assembly of these elements forms the extension ladder leveling apparatus. The extension ladder leveling apparatus is then permanently affixed to an extension ladder such that the rung assembly is in the same location as the bottom rung that was previously removed, thus forming a leveling extension ladder.  
         [0017]     It is therefore an object of the present invention to provide an extension ladder leveler which has all of the advantages of the prior art and none of the disadvantages.  
         [0018]     It is an object of the present invention to provide an extension ladder leveler that is easily and accurately adjusted.  
         [0019]     It is an object of the present invention to provide an extension ladder leveler that can be installed on any ladder having hollow side rails.  
         [0020]     It is another object of the present invention to provide an extension ladder leveler which may be easily and efficiently manufactured and marketed.  
         [0021]     It is another object of the present invention to provide an extension ladder leveler which is of durable and reliable construction.  
         [0022]     It is yet another object of the present invention to provide an extension ladder leveler which is economically affordable and available for the relevant market segments of the purchasing public.  
         [0023]     Another objective of the present invention is to provide an extension ladder leveler that is easy to use.  
         [0024]     Another objective of the present invention is to provide an extension ladder leveler that can be reused many times.  
         [0025]     Another objective of the present invention is to provide an assembly process for making the invention which uses readily available materials and components.  
         [0026]     Another objective of the present invention is to provide a method for using the invention that is easy to learn.  
         [0027]     Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be obtained by means of instrumentalities in combinations particularly pointed out in the appended claims.  
         [0028]     There has thus been outlined, rather broadly, the more important features of a ladder that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the ladder that will be described hereinafter and which will form the subject matter of the claims appended hereto.  
         [0029]     In this respect, before explaining at least one embodiment of the ladder in detail, it is to be understood that the ladder is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The ladder is capable of other embodiments and being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.  
         [0030]     As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present ladder. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0031]     The accompanying drawings illustrate a complete embodiment of the invention according to the best modes so far devised for the practical application of the principles thereof, and in which:  
         [0032]      FIG. 1  is a front plan view of related art.  
         [0033]      FIG. 2  is a left side plan view of related art.  
         [0034]      FIG. 3  is a leftt side plan view of a leveling extension ladder according to a preferred embodiment of the invention.  
         [0035]      FIG. 4  is a front plan view and right side plan view of a leveling extension ladder according to a preferred embodiment of the invention.  
         [0036]      FIG. 5  is a front plan view and right side plan view of a right rectangular tube apparatus according to a preferred embodiment of the invention.  
         [0037]      FIG. 6  is a front plan view and right side plan view of a right extension leg apparatus according to a preferred embodiment of the invention.  
         [0038]      FIG. 7  is a front plan view and right side plan view of a left extension leg apparatus installed within a left rectangular tube apparatus according to a preferred embodiment of the invention.  
         [0039]      FIG. 8  is a partial front plan view of an adjustable extension ladder showing the extension ladder leveling apparatus installed in an extension ladder according to a preferred embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0040]     The present invention is comprised of left rectangular tube assembly  2 L, right rectangular tube assembly  2 R, left extension leg assembly  3 L, right extension leg assembly  3 R and rung assembly  5 . Right extension leg assembly  3 R slides into right rectangular tube assembly  2 R and is releasably secured by dowel pin  090  through hole-dowel pin  100  in the inward side of right rectangular tube assembly  2 R to slot  080  within right extension leg assembly  3 R. Left extension leg assembly  3 L slides into left rectangular tube assembly  2 L and is releasably secured by dowel pin  090  through hole-dowel pin  100  in the inward side of left rectangular tube assembly  2 L to slot  080  within left extension leg assembly  3 L. Rung  140  in rung assembly  4  originates from the bottom rung of ladder  170 , is removed from ladder  170  and is shortened prior to becoming part of rung assembly  4 . Rung assembly  4  is permanently affixed to the two rectangular tube assemblies so that left rectangular tube assembly  2 L and right rectangular tube assembly  2 R are parallel to each other, with spring loaded pull pin assembly  070  for adjusting the leg length of left extension leg  040  facing spring loaded pull pin assembly  070  for adjusting the leg length of right extension leg  030 . The assembly of these elements forms extension ladder leveling apparatus  1 . Extension ladder leveling apparatus  1  is then permanently affixed to extension ladder  170  such that the rung portion of rung assembly  4  is in the same location as the bottom rung that was previously removed, thus forming leveling extension ladder  180 .  
         [0041]     Left rectangular tube assembly  2 L is comprised of left rectangular tube  020 , slot  080  formed in left rectangular tube  020 , hole-spring loaded assembly  130  formed in left rectangular tube  020 , and spring loaded pull pin assembly  070  permanently affixed to left rectangular tube  020 .  
         [0042]     Right rectangular tube assembly  2 R is comprised of right rectangular tube  030 , slot  080  formed in right rectangular tube  030 , hole-spring loaded assembly  130  formed in right rectangular tube  030 , and spring loaded pull pin assembly  070  permanently affixed to right rectangular tube  030 .  
         [0043]     Left extension leg assembly  3 L is comprised of left extension leg  040 , hole-dowel pin  100 , a plurality of hole-leg adjustment  110  formed in left extension leg  040 , hole-foot  120  formed in left extension leg  040 , pivot foot  150 , bolt  160  that is releaseably attached to pivot foot  150  using hole-foot  120 , and extension leg end cap  050  that is permanently affixed to the ground end of left extension leg  040 .  
         [0044]     Right extension leg assembly  3 R is comprised of right extension leg  030 , hole-dowel pin  100 , a plurality of hole-leg adjustment  110  formed in right extension leg  030 , hole-foot  120  formed in right extension leg  030 , pivot foot  150 , bolt  160  that is releaseably attached to pivot foot  150  using hole-foot  120 , and extension leg end cap  050  that is permanently affixed to the ground end of right extension leg  030 .  
         [0045]     Rung assembly  5  is comprised of rung  140  and two socket for ladder rung  060 , each of which is permanently affixed to each end of rung  140 .  
         [0046]     Referring now to  FIG. 1 , ladder  170  is shown from a front plan view. In the preferred embodiment, ladder  170  is a Werner 16 ft. Extension Ladder.  
         [0047]     Referring now to  FIG. 2 , ladder  170  is shown from a left side plan view.  
         [0048]     Referring now to  FIG. 3 , leveling ladder  180  is shown from a left side plan view.  
         [0049]     Referring now to  FIG. 4 , leveling ladder  180  is shown from a front plan view.  
         [0050]     Referring now to  FIG. 5 , right rectangular tube assembly  2  is shown, as well as socket or ladder rung  060 , spring loaded pull pin assembly  070 , slot  080  and hole-spring loaded assembly  130 .  
         [0051]     Referring now to  FIG. 6 , right extension leg assembly  3  is shown, as well as right extension leg  030 , extension leg end cap  050 , hole-dowel pin  100 , hole-leg adjustment  110  and hole-foot  120 .  
         [0052]     Referring now to  FIG. 7 , left extension tube-leg assembly  4  is shown, with left extension leg  040  being within left rectangular tube  020 , left extension leg  040 , hole-spring loaded assembly  130 , bolt  160  and pivot foot  150 .  
         [0053]     Referring now to  FIG. 8 , extension ladder leveler assembly  1  is shown, as well as right rectangular tube  010 , left rectangular tube  020 , right extension leg  030 , left extension leg  040 , extension leg end cap  050 , socket for ladder rung  060 , spring loaded pull pin assembly  070 , rung  140 , pivot foot  150  and bolt  160 .  
         [0054]     The preferred embodiment of the present invention is made as follows: 
        1) Obtaining ladder  170 ;     2) Laying ladder  170  back across two sawhorses;     3) Sliding the bottom extension of ladder  170  approximately three feet out to allow room to work on the bottom portion of ladder  170 ;     4) Removing rung  140  from ladder  170 ;     5) Laying aside rung  140 ;     6) Removing bolt  160  and pivot foot  150  from each bottom end of ladder  170 ;     7) Sliding extension leg end cap  050  flush with the end of right extension leg  030 ;     8) Welding extension leg end cap  050  to the end of right extension leg  030 ;     9) Sliding extension leg end cap  050  flush with the end of left extension leg  040 ;     10) Welding extension leg end cap  050  to the end of left extension leg  040 ;     11) Sliding left extension leg  040  inside left rectangular tube  020  until hole-dowel pin  100  is aligned with slot  080 ;     12) Installing dowel pin  090  through hole-dowel pin  100  and in slot  080 ;     13) Sliding right extension leg  030  inside right rectangular tube  010  until hole-dowel pin  100  is aligned with slot  080 ;     14) Installing dowel pin  090  through hole-dowel pin  100  and in slot  080 ;     15) Installing spring loaded pull pin assembly  070  into right rectangular tube  010 ;     16) Welding spring loaded pull pin assembly  070  to right rectangular tube  010 ;     17) Welding socket for ladder rung  060  to left rectangular tube  020 ;     18) Welding socket for ladder rung  060  to right rectangular tube  010 ;     19) Installing pivot foot  150  to left leg extension  040  by using bolt  160 ;     20) Installing pivot foot  150  to right leg extension  030  by using bolt  160 ;     21) Measuring inside opening of ladder  170  to get a first measurement;     22) Deducting the combined thickness of left rectangular tube  020  and right rectangular tube  010  from the first measurement to get a second measurement;     23) Cutting rung  140  to the length of the second measurement;     24) welding rung  140  into socket for ladder rung  060  to complete the forming of extension ladder leveler assembly  1 ;     25) sliding extension ladder leveler assembly  1  inside the opening of ladder  170  until left rectangular tube  020  and right rectangular tube  010  stops at the position of the original second rung;     26) ensuring that extension ladder leveler assembly  1  is resting firmly on the rear lip of ladder  170 ; and     27) welding the extension ladder leveler assembly in place to ladder  170  to form leveling ladder  180 .        
 
         [0082]     The preferred method of using this embodiment of the invention is comprised of the following steps. 
        1) Placing leveling ladder  180  at the desired location such that at least one of pivot foot  150  touches the surface on which leveling ladder  180  is to rest;     2) Holding leveling ladder  180  in a substantially vertical position;     3) Pulling spring loaded pull pin assembly  070  for the extension leg needing extending;     4) Extending the extension leg associated with the spring loaded pull pin assembly  070  being pulled until leveling ladder  180  is supported in a substantially vertical position; and     5) Releasing spring loaded pull pin assembly  070  such that it engages hole-leg adjustment  110  securely.        
 
         [0088]     Parts for the preferred embodiment of the invention are as follows:  
                                       PART               NUMBER   PART NAME   SPECIFICATIONS                   010   Right Rectangular Tube   ⅛″ × 1″ × 2″ Aluminum Tube       020   Left Rectangular Tube   ⅛″ × 1″ × 2″ Aluminum Tube       030   Right Extension Leg    11/16″ × 1¾″ × 18¾″ Aluminum               Bar       040   Left Extension Leg    11/16″ × 1¾″ × 18¾″               Aluminum Bar       050   Extension Leg End Cap   ⅛″ × 1″ × 2″ Aluminum       060   Socket For Ladder Rung   ⅛″ × ¾″ Aluminum       070   Spring Loaded Pull Pin   ⅜″ Weld-In Quick Pin Type           Assembly       080   Slot    5/16″ × 12¼″       090   Dowel Pin   ¼″ × ¾″       100   Hole-Dowel Pin   ¼″ Hole for Dowel Pin       110   Hole-Leg Adjustment    7/16″ Hole for Leg Adjustment       120   Hole-Foot    7/16″ Hole for Foot       130   Hole-Spring Loaded    7/16″ Hole for Installing Spring           Assembly   Loaded Assembly       140   Rung   Rung Removed from Werner               Ladder Cut &amp; Reinstalled       150   Pivot Foot   Pivot Foot with Rubber Tread       160   Bolt    5/16″ × 2½″ Bolt       170   Ladder   Werner 16 ft. Extension Ladder