Abstract:
A ladder with a fixed axle wheel adapted to facilitate relocating the ladder. The ladder may be a step ladder or an extension ladder. The ladder includes a ladder base adapted to reside on a support surface, a ladder top opposite the ladder base, and ladder sides connected by steps, the ladder sides extending between the ladder base and the ladder top. The wheel is attached to one of the sides near the ladder base and is adapted to rollably support the ladder base when the ladder is moved. The wheel may be recessed into an opening on the ladder side to allow a larger diameter wheel to be used.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a easily transportable ladder, and more specifically to a ladder with a fixed wheel on one side of the base of the ladder. 
   Maintenance personnel commonly utilize one or more ladders for various tasks. Such ladders may be foldable (or step) ladders, or extension ladders. Step ladders may range from typical household step ladders which are generally six feet high, to maintenance step ladders which may be up to twelve feet high and weigh as much as forty five pounds or more. Extension ladders may similarly vary in length and weight, and may weigh over one hundred pounds. 
   Maintenance personnel may be required to frequently relocate ladders from one work site to the next, along with moving tools, fixtures, lights, etc. Carrying heavy ladders may prove both difficult and tiring, and therefore fatiguing to a worker, who must then climb the ladder to perform tasks. Such fatigue may result in slower performance of work, or in injury. Further, due to their length, ladders are generally only be carried on the right or left side, and as such, create an uneven load on the carrier&#39;s spinal column. In some cases, long term uneven loading may injure the spinal column and/or create liability for an employer. 
   Attempts have been made to reduce the effort required to move ladders, such as the removable castors taught in U.S. Pat. No. 6,592,134 issued Jul. 15, 2003 for “Ladder Transport Systems.” The &#39;134 patent teaches a removable caster held to a ladder by a “C Clamp” type device. While the device of the &#39;134 patent address some of the needs, it does not allow the use of a large non-obtrusive or stable wheel for ladder transportation. A caster type wheel disadvantageously allows a ladder base to run down a slope, creating possibly dangerous situations. Also, the wheel of the &#39;134 patent is entirely outside the profile of the ladder, which either limits the wheel size, or creates an undesirably large extension from the ladder. 
   Thus, a need remains for maintenance ladders which are easily and steadily transportable and reduce fatigue and injury resulting from carrying heavy ladders between job sites. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention addresses the above and other needs by providing a ladder with at least one fixed axle (i.e., not a caster-type wheel) base wheel adapted to facilitate relocating the ladder. The ladder may be a step ladder or an extension ladder. The ladder includes a ladder base adapted to reside on a support surface, a ladder top opposite the ladder base, and ladder sides connected by steps, the ladder side extending between the ladder base and the ladder top. The base wheel is attached to one of the sides near the ladder base, and is adapted to rollably support the ladder base when the ladder is moved. The base wheel may be recessed into an opening on the ladder side to allow a larger diameter wheel to be used, or may be attached to the ladder using a surface mount bracket. 
   In accordance with one aspect of the invention, there is provided a ladder comprising a step portion with a fixed axle base wheel. The step portion comprises, a ladder base adapted to reside on a ladder support surface when the ladder is in use, a ladder top opposite the ladder base, first and second ladder sides extending between the ladder base and the ladder top, and steps connecting the ladder sides. The fixed axle base wheel preferably has an outside diameter between approximately three inches and approximately six inches, and more preferably approximately five inches, and is mounted to one of the ladder sides, proximal to the ladder base, and is preferably a roller scooter or a shopping cart type wheel, and more preferably a shopping cart type wheel. Advantageously, an opening may be provided in the ladder side to allow the wheel to partially intrude into the ladder to allow a larger wheel diameter without the wheel extending too far beyond the ladder side. The fixed axle base wheel is adapted to stably rollably support the ladder base when the ladder is being carried near the ladder top with steps nearly vertical (i.e., steps nearly perpendicular to the support surface or floor) and the ladder base, instead of being dragged, is rolled on the base wheel. 
   The ladder may be a step ladder having a hinged portion is connected to the step portion by a hinge at the ladder top, or an extension ladder with an extension portion slidably attached to the step portion. It is further contemplated to provide a second wheel, which is preferably a caster-type wheel, mounted to the same ladder side as the base wheel, proximal to the ladder top. If a second wheel is included, the ladder may similarly be rolled on the base wheel and second wheel. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
       FIG. 1A  is a front view of a prior art step ladder positioned for use. 
       FIG. 1B  is an edge view of the prior art step ladder positioned for use. 
       FIG. 2  is a view of the prior art step ladder positioned for carrying. 
       FIG. 3  is a view of a step ladder with a base wheel according to the present invention added to aid in transporting the ladder, with the ladder angled as it might be while being transported. 
       FIG. 4  is an edge view of the step ladder including the base wheel. 
       FIG. 5  is a view of an extension ladder with a base wheel according to the present invention added to aid in transporting the ladder, with the ladder angled as it might be while being transported. 
       FIG. 6  is an edge view of the extension ladder including the base wheel. 
       FIG. 7A  is a detailed edge view of a base wheel assembly of the ladder. 
       FIG. 7B  is a detailed side view of a base wheel assembly of the ladder. 
       FIG. 7C  is a detailed side view of a base wheel assembly of the ladder wherein the wheel is attached to the ladder using a stand-off. 
       FIG. 8  is a second embodiment of the present invention with a caster wheel added near the ladder top of a step ladder. 
       FIG. 9  is the second embodiment of the present invention with a caster wheel added near the ladder top of an extension ladder. 
       FIG. 10  is a detailed view of the caster wheel assembly on the step ladder. 
       FIG. 11A  is a side view of the wheel attached to the ladder using a riveted surface mount. 
       FIG. 11B  is a bottom view of the wheel attached to the ladder using the riveted surface mount. 
       FIG. 12  is an edge view of a ladder having two base wheels. 
   

   Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims. 
   A typical prior art step ladder is shown in  FIG. 1A , and an edge view of the prior art ladder is shown in  FIG. 1B . The prior art ladder is typically six to twelve feet high, and weighs up to forty five pounds or more. Such ladders are commonly used for painting, changing light bulbs, repairs to plumbing, etc. A view of the prior art step ladder  10  positioned for carrying is shown in  FIG. 2 . Extensive carrying of a twelve foot long prior art ladder is both fatiguing and may lead to spinal column injury. 
   The present invention provides a easily transportable step ladder  12  adapted to facilitate stable carrying, as shown in  FIG. 3 . The ladder  12  includes a ladder base  12   a  adapted to rest on a support surface (or floor)  11  when the ladder  12  is in use, a ladder top  12   b  opposite the ladder base  12   a , and ladder sides  14   a  and  14   b  with steps  13  attached thereto, ladder sides  14   a ,  14   b  extending between the ladder base  12   a  and the ladder top  12   b . A fixed axle base wheel assembly  16  is attached to the ladder side  14   a  near the ladder base  12   a , but may alternatively be attached to ladder side  14   b . The ladder  12  is shown angled relative to the support surface  11  (i.e., ladder steps  13  nearly perpendicular to the support surface and said ladder top  12   b  lifted away from the floor), as the ladder  12  might be transported by carrying the ladder top  12   b , and letting the ladder base  12   a  roll on the base wheel assembly  16 . 
   An edge view of the ladder  12  is shown in  FIG. 4 , comprising a first step portion  20   a  and a hinged portion  22 . The step portion  20   a  is fixedly attached to the ladder top  12   b , and the hinged portion  22  is pivotally attached to the ladder top  12   b  by a hinged portion pivot  24 , and may alternatively be attached by hinges. The step portion  20   a  and hinged portion  22  may be constructed from wood, fiberglass, or metal, and are generally tapered being wider at the base and narrower at the top. 
   An extension ladder  48  according to the present invention is shown in  FIG. 5  and in edge view in  FIG. 6 . The ladder  48  comprises a second step portion  20   b , an extension portion  50 , and the fixed axle base wheel assembly  16 . The extension portion  50  slidably cooperates with the step portion  20   b  to extend the ladder  48 . The ladder  48  is shown in  FIG. 5  angled relative to the support surface  11 , as the ladder  48  might be transported by carrying the ladder top, and letting the base wheel assembly  16  roll on the support surface  11 . 
   The present invention may further be applied to a ladder having a single portion (i.e., without a hinged portion or an extension portion), or a ladder with three or more hinged portions, or a combination of hinged and extension portions, and any ladder including at least one wheel assembly  16  as described above, is intended to come within the scope of the present invention. 
   A detailed edge view of the fixed axle (i.e., not a caster-type wheel) base wheel assembly  16  of the ladders  12  or  48  is shown in  FIG. 7A  and an edge view is provided in  FIG. 7B . The wheel assembly  16  includes a base wheel  26  with a base wheel fixed axle  30 . The fixed axle  30  is supported by first and second axle supports  32   a  and  32   b , and the major axis of the fixed axle  30  is substantially perpendicular to a plane parallel to the step portion  20   a , i.e., perpendicular to a plane the steps  13  (see  FIG. 3 ) lie in. The axle  30  is shown in  FIG. 7B  held in intimate contact with the ladder side  14   a  or  14   b , as seen in  FIG. 7B . The axle supports  32   a ,  32   b  are attached to the ladder side  14   a  by axle support bolts  34 . The wheel  26  protrudes partially through a wheel opening  28  in the ladder side  14   a . The base wheel assembly  16  is adapted to rollably support the ladder base  12   a  when either ladder  12  or  48  is being carried with steps  13  nearly perpendicular to the support surface  11  and the ladder base  12   a , instead of being dragged, is rolled on the base wheel  26 , and the ladder sides  14   a  and  14   b  are at a small angle to the relative to the support surface  11 . For additional strength, a boot  35  may be extended past the wheel opening  28 . Such boot  35  is preferably metal, and is shown in  FIGS. 7A and 7B . 
   An alternative embodiment of the wheel assembly is shown in  FIG. 7C  wherein the wheel  26  is attached to the ladder side  14   a  or  14   b  using a stand-off  33  to obtain greater ground clearance for the ladder  12  when being transported. 
   The base wheel  26  is preferably between approximately three inches in diameter and approximately six inches in diameter, and more preferably five inches in diameter. The base wheel  26  is preferably of the type commonly used on roller blades, roller scooters (i.e., is a roller-blade type wheel), or a shopping-cart type wheel, and more preferably a shopping-cart type wheel. The fixed axle  30  is between approximately two inches and approximately ten inches from said ladder base (i.e., measured along the length of the ladder). 
   A step ladder  12  including a second caster-type wheel assembly  18  is shown in  FIG. 8 . The wheels assembly  18  is mounted on the same ladder side  14   a  or  14   b  as the base wheel assembly  16 , but is mounted near the ladder top  12   b . Thus mounted, the second wheel assembly  18  allows the ladder  12  to be guided without requiring lifting, thus further reducing fatigue. A view of the caster-type wheel assembly  18  mounted on the extension ladder  48  is shown in  FIG. 9 . 
   A detailed view of the second wheel assembly  18  mounted to the ladder  12  is shown in  FIG. 10 . The wheel assembly  18  includes a second wheel  36  riding on a second wheel axle  38 . The axle  38  is attached to a rearward sloping second axle support  40 , which axle support  40  is typically a “U” shaped bracket. The axle support  40  is attached to a castor swivel  42 , which caster swivel  42  is rotationally attached to a caster base  44 . The caster base  44  is attached to the ladder side  14   a  by caster base bolts  46 . The second wheel  36  is adapted to rollably support the ladder top  12   b  when the base wheel  26  and the second wheel  36  are in contact with the support surface  11 . The wheel  36  is between approximately three inches in diameter and approximately six inches in diameter. 
   A side view of the wheel  26  mounted to the ladder side  14   a  using a surface mount  60  is shown in  FIG. 11A . A corresponding bottom view of the wheel  26  mounted using the surface mount  60  is shown in FUG.  11 B. The surface mount  60  is preferably attached to the ladder side  14   a  using rivets  62 , and more preferably using four rivets  62 . 
   An edge view of a two sided ladder  70  including a thick hinged portion  22   b  which includes a wheel assembly  16  adjacent to the wheel assembly  16  mounted to the stepping portion  20   a , is shown in  FIG. 12 . Wheel assemblies  16  are included on each portion of the two sided ladder  70  to support the two similarly heavy portions of the two sided ladder  70 . The hinged portion  22   b  may be a stepped hinged portion having thickness substantially similar to the stepping portion  20   a.    
   While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.