Abstract:
A ladder system is disclosed which allows for stabilizing a ladder on multiple surfaces without the need for a second person or a great deal of setup time. The collapsible ladder system includes a larger ladder section and a smaller ladder strut section which are pivotally connected at a point which is at or below the midpoint of the larger ladder section. The larger ladder section and smaller ladder strut section are connected by a rigid adjustable linkage, or spreader, at a point that is below the pivotable connection. The ladder further includes a means for stability on a variety of surfaces. At the ground contact point, the point where the ladder side rail ends and the ground meet, there are adjustable gripping feet, which can be independently or in combination vertically or angularly adjusted for maximum stability.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 12/877,310, filed on Sep. 8, 2010, entitled “Collapsible Safe Ladder,” which is a continuation-in-part of U.S. patent application Ser. No. 12/418,035, filed on Apr. 3, 2009, entitled “Collapsible Safe Ladder,” both by Floyd LaVern Vestal and Jeffrey Alan Green, hereby incorporated by reference. 
    
    
     BACKGROUND 
     Ladders have the problem that when in use, they are generally unstable. This lack of stability will often lead to injury or even death. Indeed, injuries related to ladder use are a leading problem in construction, repair and other industries. Until now, the most common way to remedy an unstable ladder was to require a second person to be positioned at the base of the ladder, or to construct a form of scaffolding, which is both costly and time-consuming. 
     Numerous modifications have been made to ladders over the years, including, for example, U.S. Pat. Nos. 202,426; 281,977; 515,783; 886,737; 1,812,119; 1,811,722; 2,007,057; 2,471,110; 2,584,197; 2,887,260; 2,934,163; 3,288,248; 3,374,860; 4,520,896; 4,565,262; 4,669,576; 5,033,584; 5,086,876; 5,165,501; 5,590,739 and U.S. Publication Number 2010/0147623. However, a need still exists for an easy-to-use, collapsible multi-surface, self-supporting ladder and ladder system with increased stability that does not require a second person or unnecessary assembly time. One aspect of the present disclosure is to provide a configuration that will help prevent injuries for individuals who climb, work on, dismount from or do any other work involving a ladder. It is contemplated that the exemplary embodiments disclosed below can be used on, inter alia, an extension ladder, pull-down attic ladder, one-piece straight ladder or any other ladder where additional stability is needed. 
     SUMMARY 
     The present disclosure endeavors to provide a collapsible multi-surface, self-supporting ladder and ladder system with an increased stability that does not require a second person or unnecessary assembly time. 
     According to a first aspect of the present invention, an apparatus for stabilizing a ladder comprises (i) two or more substantially parallel support rails, each support rail having a first end and a second end; (ii) one or more longitudal cross members connecting said substantially parallel support rails; (iii) a rod for pivotally attaching the first end of each substantially parallel support rail to a ladder, wherein said rod, which has a first end and a second end, is configured to be inserted through a hollow ladder rung such that the first and second ends protrude on each side of the hollow ladder rung for enabling the first end of each substantially parallel support rail to be removably attached to a rod end; (iv) one or more spreaders having a first end and a second end being configured to fold at a point approximately half way between the first and second ends, wherein the first end of each spreader is connected to one of the substantially parallel support rails and the second end is configured to be attached to a ladder; and (v) an adjustable shaft located at the second end of each support rail. 
     According to a second aspect of the present invention, a method for stabilizing a ladder comprises (i) connecting two support rails using one or more longitudal cross members such that the two support rails are substantially parallel, wherein each support rail has a first end, a second end and an adjustable shaft located at the second end; (ii) inserting a rod through a hollow ladder rung such that the rod&#39;s first and second ends protrude from each side of the ladder rung; (iii) pivotally connecting the first end of each substantially parallel support rail to an end of said rod; and (iv) connecting one or more spreaders between said support rails and one or more ladder rails. 
     According to a third aspect of the present invention, a ladder system comprises (i) two or more substantially parallel support rails, each support rail having a first end and a second end, wherein each support rail includes a bend at a point between the first end and a midpoint that is approximately halfway between the first and second ends; (ii) one or more longitudal cross members connecting said substantially parallel support rails; (iii) a rod for pivotally attaching the first end of each substantially parallel support rail to a ladder, wherein said rod, which has a first end and a second end, is configured to be inserted through a hollow ladder rung such that the first and second ends protrude on each side of the hollow ladder rung for enabling the first end of each substantially parallel support rail to be removably attached to a rod end; (iv) one or more spreaders having a first end and a second end and configured to fold at a point approximately halfway between the first and second ends, wherein the first end of each spreader is connected to one of the substantially parallel support rails and the second end is configured to be attached to a ladder; and (v) an adjustable spring-loaded shaft located at the second end of each support rail, wherein the shaft includes a shoe at the ground contact point. 
     In certain aspects of the present invention, a second rod may be provided for pivotally attaching the second end of each spreader to a ladder. 
     In other aspects of the present invention, said adjustable shaft may be spring-loaded and/or include a shoe at the ground contact point, wherein each shoe may have a gripping material to prevent slippage at the ground contact point and may further comprise a kick peg. 
     In another aspect of the present invention, each substantially parallel support rail may constructed from a single, continuous material. Each substantially parallel support rail may be constructed from a metal or metal alloy. 
     In yet another aspect of the present invention, each substantially parallel support rail may include a bend at a point between the first end and a midpoint which is approximately halfway between the first and second ends. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       These and other advantages of the present invention will be readily understood with reference to the following specifications and attached drawings wherein: 
         FIG. 1  is a front angular perspective view of a first embodiment of a ladder system of the present invention mounted on a pull-down ladder in the collapsed position; 
         FIG. 2  is a front angular perspective view of the first embodiment of a ladder system of the present invention mounted on a pull-down attic ladder in the extended position; 
         FIG. 2A  is an exploded view of the adjustable spreader of the ladder system in  FIG. 2 ; 
         FIG. 2B  is an exploded view of the adjustable foot of the ladder system in  FIG. 2 ; 
         FIG. 3  is a side angular perspective view of a second embodiment of the adjustable ladder system of the present invention mounted on an extension ladder; 
         FIG. 3A  is an exploded view of the adjustable spreader of the ladder system in  FIG. 3 ; 
         FIG. 3B  is an exploded view of the adjustable foot of the ladder system in  FIG. 3 ; 
         FIG. 4  is a side angular perspective view of a second embodiment of the adjustable ladder system of the present invention mounted on an extension ladder set up to allow for a greater ground footprint; 
         FIG. 4A  is an exploded view of the adjustable spreader of the ladder system in  FIG. 4 ; 
         FIG. 4B  is an exploded view of the adjustable foot of the ladder system in  FIG. 4 ; 
         FIG. 5  is a side angular perspective view of a second embodiment of the adjustable ladder system of the present invention mounted on an extension ladder set up to allow for a maximum ground footprint; 
         FIG. 5A  is an exploded view of the fully extended adjustable spreader of the ladder system in  FIG. 5 ; 
         FIG. 5B  is an exploded view of the adjustable foot of the ladder system in  FIG. 5 ; 
         FIG. 6  is an exploded view of a partially extended adjustable spreader of the ladder system; 
         FIG. 7  is a side view of the ladder system showing the spreader in a locked extended position; 
         FIG. 8  shows an alternative foot with a rubber boot; 
         FIG. 9  shows an alternative foot where the shaft forms a spike; 
         FIG. 10  shows the safety latch mechanism; 
         FIG. 11A  is a side view of the ladder system with a spring-loaded adjustable foot where the fixed spreader is in a locked extended position; 
         FIGS. 11B-E  illustrate a ladder system having a spring-loaded adjustable foot wherein the ladder system is removably attached to a ladder; and 
         FIGS. 12A-D  are exploded views of the operation of the spring-loaded adjustable foot of the ladder system of  FIGS. 11A-D . 
     
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments of the present invention will be described hereinbelow with references to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail, since such minutia would obscure the invention in unnecessary trivia. 
     Referring to  FIG. 1 , an embodiment of the ladder system  20  mounted to pull-down ladder  10  in a partially collapsed state is depicted. The ladder system  20 , or smaller strut section, includes a pair of support rails  22 ,  24  substantially identical but of opposite hand, a lateral cross member strut  26 , a pair of adjustable feet  28 ,  30  substantially identical but of opposite hand, and a pair of rigid adjustable spreaders  32 ,  34  substantially identical but of opposite hand. 
     Referring now to  FIG. 2 , the ladder system of  FIG. 1  is shown fully extended. In this embodiment, the support rails  22 ,  24  are substantially parallel, however in an alternative embodiment the rails  22 ,  24  may be outwardly flared at their lower ends to create a wider stance, allowing for increased stability. In either embodiment, each of the rails  22 ,  24  has a foot  28 ,  30  located at the end of the rail  22 ,  24  where contact is made with the ground, referred to as the ground contacting point, while the opposite end of each of the rail  22 ,  24  is pivotally connected, using pivotal connectors  36 ,  38 , to its respective rails  40 ,  42  of the pull-down ladder  10 . The pivotal connectors  36 ,  38  can be either permanently connected by means of a bolt, rivet, pivoting hinge, etc. or alternatively, the pivotal connection can be removably attached to the rails  40 ,  42  of the pull-down ladder  10  by means of, for example, a clamping structure, allowing the ladder system to be used on a multitude of preexisting ladders, including, for example, drop-down and extension ladders. As will be described in greater detail below, an exemplary method for removably attaching each rail  22 ,  24  to its respective rail  40 ,  42  is illustrated in  FIGS. 11B and 11C . 
     Referring to  FIG. 2A , an exploded view of an adjustable spreader of the ladder system, the depicted rigid adjustable spreader  32 ,  34  is generally composed of two rigid spans  32   a ,  32   b  that are pivotally connected at their ends with a shank  33   a  and lock pin  33   b  such that the two rigid spans  32   a ,  32   b  can lock in the fully extended position to form a spreader between the rails  22 ,  24  in the lower section, between the midpoint of the ladder rail length and the ground contact points, of their respective rails  40 ,  42  of the pull-down ladder  10 . In other embodiments, an extension ladder or step-to-straight ladder may be stabilized in lieu of a pull-down ladder. For example, when applied to a 28-foot extension ladder, the rigid span, or spreader, is connected to the existing ladder approximately 17 inches (nearly 1/20th the total length of the ladder) off the ground. The pivotal connection may be laterally adjustable such that the length of the spreader can be increased or decreased thereby increasing or decreasing the angle created between the ladder system rails  22 ,  24  and their respective rails  40 ,  42  of the pull-down ladder  10 . In certain embodiments, as seen in  FIG. 11A , the spreader may a standard spreader  62  with a fixed length S as used in a traditional step ladders. The length S of the fixed spreader is determined based on the total length L of ladder being stabilized and the desired base or footprint size. For example, in a preferred embodiment using a standard spreader  62 , the spreader&#39;s  62  total length S, when applied to a 28-foot extension ladder, may be approximately 24 inches. The approximately 24-inch spreader may, however, be used for a range of ladder sizes (e.g., 24′ to 40-foot extension ladders). For smaller ladders (e.g., a 16-foot extension or step-to-straight ladder) a spreader length S of approximately 18 to 19 inches would be preferred. Naturally, various spreader lengths S may be used depending on the application and length L of the ladder (e.g., a longer spreader may be used for longer ladders which may require a larger footprint or base). As seen in the figures, the rails  22 ,  24  may be predrilled with more than one set of holes near the shaft  44  so that a single fixed length spreader  62  may be used with a number of ladders lengths and sizes by simply installing the spreader  62  at different locations on the rails  22 ,  24 . 
     Referring to  FIG. 7 , another means for connecting two rigid spans  32 A,  32 B is shown. The two rigid spans  32 A,  32 B are connected to one another at two points, with a pen anent laterally slideable connection and a second connection that locks the span at the specified length using the safety stop  84  and a pin  33 A that penetrates the hole of the safety stop  84  and the desired hole in the rigid span  32 B therefore locking the overall length of the spreaders  32 ,  34 . When the pin  33 A is not in the safety stop  84 , the spreader can be folded at the slideable connection. To prevent misplacement, the pin  33 A may be tethered to the ladder or ladder system  20 . In an alternative embodiment, there may be more than two rigid spans comprising the spreader, and the connection between the at least two rigid spans can be by another means, including, but not limited to, a threaded post and wing nut or screw caps  50 . 
     Referring to  FIG. 2B , an exploded view of a ladder system foot  28  is shown. The feet  28 ,  30 , located at the end of the rails  22 ,  24  at the ground contact point, are both angularly and vertically adjustable. Each of said feet  28 ,  30  is composed of two primary components, a vertically extendable shaft  44  and shoe  46  pivotally connected to the shaft  44  using a pivotal connector  48 . The pivotal connector  48  allows the shoe  46  to conform to the angle of the ground on which it is placed. If required, the pivotal connector  48  can be tightened, therefore locking the shoe  46  in the preferred arrangement. The length of the rails  22 ,  24  depends on the application of the ladder system. When stabilizing a shorter ladder, the rails  22 ,  24  may be shorter than rails  22 ,  24  being used to stabilize a longer ladder, or when a larger foot-print or base is needed for stabilizing a ladder. For example, when a ladder having a length L of 6 to 23 feet (e.g., a 16-foot extension ladder or step-straight ladder) is used, the rails  22 ,  24  may be approximately 21 inches in length K from the foot-end to the bent portion  64  of the rails  22 ,  24 . Similarly, when a ladder having a length L of 24 to 40 feet (e.g., a 28-foot extension ladder) is used, the rails  22 ,  24  may be approximately 30 inches in length K from the foot-end to the bent portion of the rails  22 ,  24 . Naturally, the length K of the rails  22 ,  24  may vary from the provided measurements. 
     The underside of the shoe  46  includes a gripping material  76  to minimize slippage at the ground contact point. Depending on the application, said gripping material  76  could be a rubber pad for use on a relatively smooth hard surface, spiked (as seen in  FIG. 9 ) or staggered for use on grass and packed dirt, or even a planar foot that creates a large shoe surface area, therefore preventing the foot  28 ,  30  from sinking into soft ground. Depending on the choice of shoe  46 , the ladder system  20  can be used on ground surfaces such as concrete, dirt, steel, tile, grating, brick, stone and most floor materials. The pivotable connector  48  between the shaft  44  and shoe  46  may be permanent or removable, therefore allowing one to interchange the shoe  46  depending on the application or environment. 
     Alternative foot embodiments are shown in  FIG. 7  wherein the shoe  46  is directly coupled to the end of the rails  22 ,  24  and  FIG. 8  wherein the shaft  44  comes into direct contact with the ground or through an optional intermediate such as a rubber boot  80 . The rubber boot  80  acts as a gripping material and prevents the shaft  44  from scratching the ground. Referring now to  FIG. 9 , in lieu of a rubber boot  80 , the end of the shaft  44  may be pointed to increase ground penetration, therefore preventing slippage on dense penetrable surfaces such as dirt, grass, gravel and rock. 
     Referring now to  FIGS. 3-5 , in this embodiment, a side view of the ladder system&#39;s versatility is shown when the ladder system  20  is installed on a traditional straight ladder  60 ; however, the system is not restricted to a straight ladder but can be applied to any ladder where additional stability is required.  FIGS. 3-5  show three adjustment configurations where the rigid adjustable spreaders  32 ,  34  have been laterally adjusted to create a larger overall footprint by increasing the distance between the larger ladder section  60  and the ladder system  20 , the shaft  44  is vertically adjusted to ensure that steady contact between the shoe  46  and the ground is maintained, and the shoe  46  adapts to the angle and terrain of the ground. The shaft  44  as shown in  FIGS. 3B ,  4 B and  5 B is adjusted using two nested tubes  56 ,  58  with a plurality of holes  52  which, when adjusted to the appropriate height, can be aligned and locked into place using a set pin  54 . In alternative embodiments, a push-button adjustment mechanism with or without a locking ring may be used to secure the two nested tubes  56 ,  58 , the nested tubes  56 ,  58  may be locked at a specified length with a slip nut and washer or the two nested tubes  56 ,  58  may be threadedly coupled wherein the overall shaft  44  is extended or shortened by rotating the shoe  46  and/or lower nested tube  56 . In another embodiment, as depicted in  FIGS. 12A-12D , the nested tubes  56 ,  58  may be spring-loaded. This may be accomplished, for example, using a spring  68  and series of notches  70 , or grooves, to quickly and safely adjust the height of the shaft. The upper nested tube  58  includes a series of angled notches  70  configured to receive one or more pegs  72 . The lower nested tube  56  would include one or more pegs  72  which may be received by the angled notches  70  in the upper nested tube  58 . A spring  68  is housed in the hollow space within the nested tubes  56 ,  58  and creates a constant force pulling the tube ends toward each one another in direction B, therefore shortening the shaft  44 . To make adjustments to the shaft&#39;s  44  length, a user could twist the foot  46  and/or lower nested tube  56  in direction C so that the one or more pegs  72  is withdrawn from one or more angled notches  70 . The user may then pull the foot  46  and/or lower nested tube  56  in direction A until the desired shaft  44  length has been reached. Once the desired length has been reached, the user twists the foot  46  and/or lower nested tube  56  in direction D causing the one or more pegs  72  to be inserted into the one or more angled grooves  70 . The tension created by the spring  68  pulls nested tube  56  in direction B and securely holds the one or more pegs  72  in the one or more angled grooves  70 . When weight is applied to the ladder or shaft  44 , a force is created in direction B that further secures the one or more pegs  72  in the one or more angled grooves  70  to prevent collapsing and/or shortening of the shaft  44 . 
     Turning now to  FIG. 11B , a technique for removably attaching each rail  22 ,  24  to its respective rail  40 ,  42  is illustrated. In certain situations, it may be advantageous to removably attach each rail  22 ,  24  to a ladder without drilling or otherwise modifying the original ladder structure. In fact, certain ladder manufactures may prohibit the drilling of holes though a ladder rail alleging that it could weaken the structural integrity of the ladder. While this may not necessarily be true, the ladder manufacturer may nevertheless void the warranty. Therefore, to circumvent the risk of voiding a manufacturer warranty, a user may wish to safely attach a ladder system without requiring any modifications to the original ladder. This may be accomplished by, for instance, inserting a rod  78  through the hollow rung  86  of a ladder  60 . In order to receive a nut  82 , the rod  78  may be threaded at the ends or, in the alternative, threaded across the entire length of the rod  78 . In order to reduce friction and/or prevent the rod  78  from becoming misaligned during use, a bushing  80  may be inserted on each end of the rod  78  such that, when assembled, a bushing  80  is located between each ladder  60  rail  40 ,  42  and the corresponding ladder system rail  22 ,  24 . The bushing  80  may be fabricated from any material known in the art of bushing manufacture, including, for example, polyacetal, nylon, fiberglass and/or metallic materials. As illustrated in the  FIG. 11B , the bushing  80  may be configured with two different outer diameters, wherein the narrower diameter may be configured to snugly fit within the end of the hollow rung  86  while the second larger diameter would ensure that the bushing  80  remains at the rail  40 ,  42  surface. Once the bushings  80  have been installed, the rails  22 ,  24  may be mounted on the rod  78  ends and secured using, for example, a nut  82 . The nut  82  may be a traditional nut or a nut design to prevent loosening (e.g., a lock nut). Alternatively, as seen in  FIG. 11E , to ease tightening and loosening (e.g., during assemble, disassembly and adjustment), the rails  22 ,  24  may be mounted on the rod  78  ends and secured using a threaded knob  88 . As seen in both  FIGS. 11B and 11E , the spreader  62  may be attached to the ladder  60  using the same through-the-rung techniques as those used to attached the rails  22 ,  24 . Alternatively, the spreaders  62  may be attached using more traditional methods, such as traditional nuts  82  and bolts  84 . 
     While the ladder system illustrated in  FIG. 11B  presents an exemplary method for removeably attaching each rail  22 ,  24  to a ladder without drilling or otherwise modifying the original ladder, it should be appreciated that one having ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Turning now to  FIGS. 11C and 11D , the ladder system of  FIG. 11B  is shown fully assembled.  FIG. 11C  illustrates the ladder system in a fully extended state while  FIG. 11D  illustrates the ladder system in a folded state.  FIG. 11E  illustrates the ladder system of  FIG. 11B  wherein a threaded knob  88  is used. One or more threaded knobs  88  may be use in conjunction with, or in lieu of nut  82 , where the threaded knobs  88  and nut  82  may be interchanged as desired by the user. For example, as illustrated in  FIG. 11E , the user may wish to secure the spreader using a nut  82 , but may prefer to use a knob  88  to secure each rail  22 ,  24 . Similarly, in certain embodiments, a user may wish to use a knob  88  on only one end while the other of the rod  78  is secured using a nut  82  or a more permanent means such as welding a nut or bushing to the rod  78 . The knob  88  may be fabricated from any material known in the art of knob manufacture, including, for example, polyacetal, nylon and/or metallic materials. To enable coupling with a rod  78 , the knob  88  is preferably threaded to receive the threads of the rod  78 . 
     As seen in  FIGS. 1-5  and  11 A-E, each of the rails  22 ,  24  includes a bend  64 ,  66  near the point where the rails  22 ,  24  are connected to ladder rails  40 ,  42 . The bends  64 ,  66  allow for the ladder system  20  to lay flush, or substantially parallel, to the existing ladder, when in a closed position. In a preferred embodiment, the bends  64 ,  66  in rails  22 ,  24  are approximately 45 degrees off the rails&#39;  22 ,  24  center line(s). The length and angle of the bent portion may however be adjusted based on the application, length and shape of the ladder system  20  or rails  22 ,  24 . Referring to  FIG. 10 , the ladder system may be locked in the closed position using the safety latch  82  which locks the ladder system  20  to the ladder being stabilized. The safety latch can be used with a plurality of ladders, including but not limited to pull-down ladders, straight ladders and extension ladders.  FIG. 10  shows the safety latch  82  attached to the lateral cross member strut  26 , however in another embodiment, the safety latch  82  may attach to a loop or other latch receptacle. 
     The ladder system  20  structure as described can be constructed from any material known in the art of ladder fabrication, including but not limited to wood, metal, metal alloys, fiberglass, composites, carbon fiber, plastic or a combination thereof. Similarly, the rails of the smaller strut section or ladder system  20  need not be the same material as the larger ladder section. In certain embodiments, each of the ladder system rails  22 ,  24  may be constructed from a single, continuous material (e.g., a singular, unbroken material). By constructing the rails  22 ,  24  from a single, continuous material, fewer connection points (e.g., welds/joints) are needed, thereby decreasing costs while also strengthening the rails  22 ,  24 . For example, each rail may be constructed from a single length of metal or metal alloy which may be cut, molded or stamped in the shape of the support rail. The ladder system  20  may also include a kick peg  74  mounted on one or both of the ladder system rails  22 ,  24  or other stable ladder system  20  surface. The kick peg  74  allows for easy employment of the ladder system because the user is able to spread the ladder system away from the existing ladder using only a foot. 
     While the present invention has been described with respect to what are currently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation, so as to encompass all such modifications and equivalent structures and functions. 
     All U.S. and foreign patent documents, all articles, all brochures and all other published documents discussed above are hereby incorporated by reference into the Detailed Description of the Preferred Embodiment.