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CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a non-provisional application that claims priority to U.S. provisional patent application Ser. No. 61/654,291, filed Jun. 1, 2012, the disclosure of which is hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    This invention relates to the field of ladders and more particularly to an adjustable mechanism for supporting a ladder, such as an extension ladder. 
       BACKGROUND 
       [0003]    Ladders of various sizes, shapes, and uses are well known in the art. But for a professional who needs to perform many different elevated tasks, often many different ladders are required. A professional may need an A-frame ladder (step ladder) for free-standing work, an extension ladder for very high work, and a platform ladder for horizontal elevated work. It is inconvenient and expensive to store and transport this many ladders. 
         [0004]    What is needed is a ladder system that provides adjustability and versatility to allow many uses of a single ladder. 
       SUMMARY 
       [0005]    Elevated work often requires the use of an extension ladder. But the unsteady nature of extension ladders makes such work hazardous. A-frame ladders, while more stable, are unavailable in heights above twenty feet. Thus, higher work necessitates either scaffolding or an extension ladder. The disclosed adjustable ladder support mechanism solves the problem of unstable extension ladders with a mobile base that can be moved by one man, the base then expanded in both length and width. With the stable base set up, the ladder can be extended, the angle adjusted, and the operator can safely climb the ladder. Worries of the ladder slipping sideways off the ledge against which it is leaned are eliminated. 
         [0006]    The adjustable ladder support mechanism has two main sections: the base, which provides stability, and the tower, which raises the ladder above the ground. 
       The Base 
       [0007]    The base provides the platform for the adjustable ladder support mechanism. The footprint, or area of the supporting surface (e.g., ground, driveway, etc.) covered by the base, is supported at each corner by wheels. The footprint is expandable through movable outriggers, or movement of the supporting wheels themselves. 
         [0008]    Each corner of the base moves outward to increase size of the footprint, and thus stability. Depending upon the embodiment, this expansion can be performed manually or by use of a powered system. If manually, it may be through a hand-cranked screw mechanism, if automated, through any type of linear actuator (e.g., mechanical actuators, hydraulic actuators, pneumatic actuators, piezoelectric actuators, electro-mechanical actuators). 
         [0009]    The base allows for expansion through the use of sliding joints. The example embodiment uses nested box beams, one sliding into another, to allow for expansion/contraction of the base. 
         [0010]    The wheels present at the corners are either mounted on a horizontal axle for rotation in a single direction, or allowing for spinning, such as is seen in casters. 
       The Tower 
       [0011]    The tower rises from the base, substantially forming a shape resembling a capital letter “A.” A first set of legs of the tower is of a fixed length in the embodiment shown. The second set of legs can either be of a fixed length, or of an adjustable length. Adjustable length allows the legs to expand or collapse, changing the height and position of the peak of the tower. 
         [0012]    In alternative embodiments, the first set of legs is also of variable length. 
         [0013]    In an embodiment with legs of adjustable length, the sets of legs that make up the tower are hingedly attached to the base. The hinged connections can be of any type, although simple barrel hinges or pivot hinges are shown in the embodiment. 
         [0014]    The sets of legs optionally include steps, allowing an operator to climb the steps of the adjustable ladder support mechanism to reach the extension ladder mounted at the peak of the tower. 
       Ladder Gripping Mechanism 
       [0015]    At the peak of the tower is the ladder gripping mechanism, where the adjustable ladder support mechanism attaches to an extension ladder. The extension ladder used need not be a specific type, although the dimensions of the ladder gripping mechanism may need to be adjusted for unusually sized extension ladders. 
         [0016]    The base section, or larger section, of the extension ladder is held by the ladder gripping mechanism. The fly section, or smaller section, is free to extend from the base mechanism. 
         [0017]    The fly section of ladder is held in place relative to the base section of the ladder by rung locks, as are common in extension ladders. 
         [0018]    The ladder gripping mechanism is hingedly attached to the tower. A linear actuator of any type (e.g., mechanical actuators, hydraulic actuators, pneumatic actuators, piezoelectric actuators, electro-mechanical actuators) is used to change the angle of the ladder gripping mechanism, and thus the angle of the ladder. 
         [0019]    The ladder is held within the ladder gripping mechanism by a pin that passes through the ladder gripping mechanism itself and into a hole created in the extension ladder by the penetration of a ladder rung. 
         [0020]    The chain drive is used to move the extension ladder through the ladder gripping mechanism. In order to use the chain drive the proximal end of the chain is affixed to the proximal end of the base section of the extension ladder. The ladder pin is pulled to release the base section of the extension ladder, and then the crank is turned to pull the proximal end of the chain, raising the ladder. When the ladder is in the desired location the ladder pin is reinserted. 
       Extension Ladder 
       [0021]    As discussed, for most embodiments the extension ladder is separate. A standard extension ladder consists of a base section that generally rests on the ground, and a fly section that extends from the top of the ladder. Extension is often performed by attaching one end of a cord to a rung near the bottom of the fly section of the ladder, and running the cord through a pulley near the top of the base section of the ladder. Pulling the cord results in the fly section of the ladder being pulled upward. Once the fly section of the ladder is at its desired location, rung locks are used to lock the two sections of the ladder relative to one another. 
         [0022]    Furthermore, optional ladder plates may be used to affix the base section and the fly section of the ladder together. 
       Ladder Rung Platform 
       [0023]    The adjustable ladder support mechanism can also be used as a type of scaffolding. By lowering the angle of the ladder gripping mechanism to an angle near horizontal, and adjusting the length of the tower legs if needed, the extension ladder is used in a horizontal position and acts as a work platform. 
         [0024]    But using a ladder in a horizontal position may result in the user stepping into the spaces between the rungs. 
       Folding Rung Covers 
       [0025]    The adjustable ladder support mechanism optionally includes folding covers that provide a platform over the extension ladder. The folding rung covers are intended for use when the extension ladder is in a near-horizontal position and the spaces between the rungs are a danger, rather than a location for one&#39;s foot. 
         [0026]    The folding rung covers are of any number of plates, connected to the extension ladder by hinges. The exemplary folding rung covers are comprised of two plates per cover, with a total of two covers being sufficient to fill the width of the extension ladder. 
         [0027]    The folding rung covers are anticipated to use tracks integrated with the rungs that guide the folding rung covers from open to closed positions. 
         [0028]    The folding rung covers are of sufficient strength to allow a user to walk on them. 
         [0029]    Option handrails are also shown. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which: 
           [0031]      FIG. 1  illustrates a side view of an embodiment of the adjustable ladder support mechanism. 
           [0032]      FIG. 2  illustrates an isometric view of an embodiment of the adjustable ladder support mechanism 
           [0033]      FIG. 3  illustrates a side view of an embodiment of the adjustable ladder support mechanism, with the support in a horizontal position. 
           [0034]      FIG. 4  illustrates a close-up of the section of the adjustable ladder support mechanism that interfaces with the extension ladder 
           [0035]      FIG. 5  illustrates a view of the optional folding covers for the ladder rungs. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. 
         [0037]      FIG. 1  illustrates a side view of an embodiment of the adjustable ladder support mechanism. The adjustable ladder support mechanism  1  is shown, including its two main components of the base  2  and tower  4 . The exemplary embodiment of the tower  4  has two legs, a first tower leg  6  and a second tower leg  8 . The first tower leg  6  is shown as extending above the point at which it meets the second tower leg  8 , terminating at the ladder hinge  10 . Ladder hinge  10  connects the tower  4  to the ladder gripping mechanism  50 . 
         [0038]    The tower  6  is shown connecting to the base  2  through optional hinges, specifically the first tower hinge  12  and the second tower hinge  13 . First tower hinge  12  and second tower hinge  13  are needed when the inclination sliding joint  14  is present. Inclination sliding joint  14  is any type of joint that allows the length of the second tower leg  8  to be altered. Inclination sliding joint  14  is shown as a slip joint, allowing the lower portion of second tower leg  8  to slide within the upper portion of second tower leg  8 . The position is then fixed using any number of known methods, including spring pins, bolts, etc. 
         [0039]    The combination of the first tower hinge  12 , second tower hinge  13 , and inclination sliding joint  14  allows the inclination of the legs to be modified. Optionally, first tower leg  8  also incorporates a sliding joint (not shown). 
         [0040]    The adjustable ladder support mechanism  1  can be used with extension ladders of great height, making tipping an issue. The base  2  of the adjustable ladder support mechanism  1  is equipped with multiple outriggers to increase stability before use. This includes front outriggers  20  and rear outriggers  26 / 28 . Front outriggers  20  are shown as increasing the length of the base  2 , although it is anticipated that front outriggers  20  can also be used to extend the width. Front outriggers are shown as contacting the ground through front wheels  24 . 
         [0041]    Front outriggers  20  can be extended using extension linear actuator  31 , which increases the length of the base through the extension sliding joint  30 . Extension sliding joint  30  is any type of joint that allows the length of the base  2  to be altered. Extension sliding joint  30  is shown as a slip joint, allowing one portion of the base  2  to slide into another portion of the base  2 . The position is then fixed using any number of known methods, including spring pins, bolts, etc. 
         [0042]    Rear outriggers  26 / 28  are shown extending the width of the base  2 , although it is anticipated that rear outriggers  26 / 28  can also be used to extend the width. Rear outriggers are shown with two sets of wheels, a first set of rear wheels  26  that are at a fixed position on the base, and a second set as part of the outrigger foot  28 . Outrigger foot  28  can be wheels, as shown in the exemplary embodiment, or a non-rolling end, such as a foot or pad. The wheels can be locking or non-locking. 
         [0043]    The exemplary embodiment is shown with steps  32  that allow an operator to climb to the ladder. 
         [0044]    Moving to the top of the tower  4 , ladder gripping mechanism  50  is shown (for clarity, shown in  FIG. 4  without the ladder). The ladder hinge  10  and ladder inclination linear actuator  16  work in combination to allow the ladder gripping mechanism  50  to alter the inclination angle  62  of the extension ladder  80 . 
         [0045]    Referring to  FIG. 2 , an isometric view of an embodiment of the adjustable ladder support mechanism  1  is shown. Extension ladder  80  is shown, specifically the base section  84  and fly section  82 . Extension ladder  80  includes side rails  86 , which connect rungs  88 . 
         [0046]    The locking mechanism between the fly section  82  and base section  84  is the standard rung lock  90  that is common to extension ladders. Furthermore, the rope and pulley system  92  common to extension ladders, used to extend the fly section  82  of the ladder  80  while at the base of the ladder  80 , remains operational. 
         [0047]    Referring to  FIG. 3 , a side view of an embodiment of the adjustable ladder support mechanism, with the support in a horizontal position is shown. The adjustable ladder support mechanism  1  has the ability to hold the ladder in a horizontal position for use as scaffolding. Or, as shown in  FIG. 3 , to hold the extension ladder at an inclination angle  62  (see  FIG. 1 ) of zero degrees. The inclination linear actuator  16  operates to fix the inclination of the ladder gripping mechanism  50 , and the legs  6 / 8  of the tower  2  optionally include vertical adjustability to support changes in the elevation of the extension ladder  80 . 
         [0048]    Optional ladder plates  77  are shown affixing the fly section  82  of the extension ladder to the base section  84 . 
         [0049]    Referring to  FIG. 4 , a close-up of ladder gripping mechanism  50  is shown. The base section  84  of the extension ladder  80  is held by the ladder gripping mechanism  50 . The base section is held between the lower ladder rest surface  52  and the upper ladder rest surface  54 . Ladder pin  66  connects the ladder gripping mechanism  50  to the base section  84  of the extension ladder  80  by penetrating a hole created in the sidewall  86  by a rung  88 . 
         [0050]    Drive chain  56  is operated by drive gear  58 , in turn rotated by crank  110  on axle  111 . Drive chain  56  is supported by carrier gears  60 . Axle  111  also rotates an additional drive gear (not shown) on the opposite side of the ladder gripping mechanism  50 . 
         [0051]    The drive chain  56  has two ends, a chain proximal end  68  and a chain distal end  70 . Chain proximal end  68  is affixed to the proximal end of the base section  84  of the extension ladder  80 . The ladder pin  66  is pulled to release the base section  84  of the extension ladder  80 , and then the crank  110  is turned to reduce the length of chain between the chain proximal end  68  and the crank  110 , acting to pull the proximal end  68  of the drive chain  56 , thus raising the extension ladder  80 . When the extension ladder  80  is in the desired location the ladder pin  66  is reinserted. 
         [0052]    Referring to  FIG. 5 , a view of the optional folding rung covers  120  for the ladder rungs is shown. 
         [0053]    The exemplary folding rung covers  120  include an inner plate  100  connected to the side rail  86  by an inner hinge  104 , and to the outer plate  102  by an intermediate hinge  106 . The hinges  104 / 106  are any type of hinge, but likely to be a type of continuous hinge, commonly known as a piano hinge. 
         [0054]    The inner plate  102  is held in alignment by interfacing with one or more tracks  108  mounted on, or intrinsic to, rungs  88 . 
         [0055]    Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. 
         [0056]    It is believed that the system and method as described and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.

Summary:
The disclosed adjustable ladder support mechanism solves the problem of unstable extension ladders with a mobile base that can be moved by one man, the base then expanded in both length and width. With the stable base set up, the ladder can be extended, the angle adjusted, and the operator can safely climb the ladder. Worries of the ladder slipping sideways off the ledge against which it is leaned are eliminated. 
     The adjustable ladder support mechanism has two main sections: the base, which provides stability, and the tower, which raises the ladder above the ground.