Abstract:
A quick-release ladder stabilizer and leveler that is fast and easy to use. The combined ladder stabilizer and leveler levels a ladder on sloping, uneven, or stepped surfaces, significantly broadens the ladder base for stability, retrofits to existing ladders without ladder modification, and in addition is fast to attach/remove, easy to adjust by a single user, and readily portable.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 12/985,702 filed on 2011-01-06, which application claims priority to US Provisional Patent Application No. 61/294,451 filed on 2010 January 12, which applications are incorporated herein by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    Disclosed embodiments relate to ladder stabilizer and leveler apparatuses. 
       BACKGROUND 
       [0003]    Ladder falls are a leading industrial safety issue. There are approximately 200,000 ladder related accidents in the United States each year. Standard commercial ladders are inherently unstable due to their narrow base width, and feet designed for level placement. Often, users of these ladders need to lean or carry awkward loads while on ladders placed on sloping, uneven, or stepped surfaces and this combination can result in the center of gravity of the ladder load extending beyond the ladder feet, thereby placing the user at high risk of a ladder fall. 
         [0004]    Numerous ladder leveler designs (e.g. U.S. Pat. No. 5,542,497) disclose extendable substitute ladder feet in order to keep the ladder rails vertical when placed on inclined ground. However, these designs do not significantly widen the ladder base and therefore the ladder remains prone to tipping. 
         [0005]    Numerous ladder stabilizer designs (e.g. U.S. Pat. No. 6,527,084) disclose pivoting telescoping support feet extending from the ladder to ground at a distance from the ladder. These designs provide a measure of stabilization against lateral movement of the ladder, however, they are generally unsuited for stabilization if one of the ladder feet is not in contact with the ground or the ladder rails are not vertical. 
         [0006]    U.S. Pat. No. 6,336,521 discloses a ladder leveling device with an arch structure that fails the ANSI/OSHA requirements that the first rung, in this case the arch, is flat and that rung-spacing is twelve inches. Furthermore, since widening the arch base increases the height of the arch and ANSI standards require that the first rung (the arch) is no higher than fourteen inches off the ground, the arch base width is restricted, and consequently the stability of the ladder leveling device is limited. 
         [0007]    U.S. Pat. No. 1,424,934 discloses a ladder leveler for use on hillsides. The ladder leveler requires permanent ladder modification, and is not readily separable from the ladder. Furthermore, the leveler significantly obstructs foot placement on the first rung of the ladder, and thus violates OSHA safety requirements. 
         [0008]    U.S. Pat. No. 5,507,364 discloses a ladder leveling/stabilizing device which is not readily separable from the ladder and which utilizes a friction-based locking mechanism that can fail if not tightened sufficiently by the ladder user, or if exposed to lubricants. Furthermore, the leveler significantly obstructs foot placement on the first rung of the ladder. 
         [0009]    Most ladder leveler and/or stabilizer designs require permanent ladder modifications (such as drilling of holes), which can compromise ladder integrity and void ladder warranty. Furthermore, ladder levelers/stabilizers that do not implement quick-release mechanisms for ladder attachment hinder their usage with multiple ladders and can make ladder transportation more difficult. Those that are designed to retrofit without modification are typically time-consuming to install/remove, or difficult for one person to adjust without assistance. 
       SUMMARY 
       [0010]    Clearly, there is a need for a combined ladder stabilizer and leveler that levels a ladder on sloping, uneven, or stepped surfaces, significantly broadens the ladder base for stability, retrofits to existing ladders without ladder modification, and in addition is fast to attach/remove, easy to adjust by a single user, and readily portable. 
         [0011]    Disclosed embodiments of the stabilizer and leveler for a ladder include: (a) a base assembly; (b) two feet respectively attached to the left and right sides of the base assembly; (c) a ladder harness assembly pivotally attached to the base assembly, the ladder harness assembly comprising means for removably attaching the ladder harness assembly to a ladder; (d) retaining means for preventing separation of the ladder harness assembly from the base assembly; and (e) selective locking means for preventing rotation of the ladder harness assembly relative to the base assembly when the selective locking means is engaged. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Disclosed embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. 
           [0013]      FIG. 1  illustrates a front elevation of an embodiment of the quick-release ladder stabilizer and leveler with attached ladder on inclined ground surface. 
           [0014]      FIG. 2  illustrates a side elevation of an embodiment of the quick-release ladder stabilizer and leveler with attached ladder. 
           [0015]      FIG. 3  illustrates a front elevation of an embodiment of the quick-release ladder stabilizer and leveler with attached ladder. 
           [0016]      FIG. 4  illustrates a rear elevation of an embodiment of the quick-release ladder stabilizer and leveler with attached ladder. 
           [0017]      FIG. 5  illustrates a front perspective exploded view of an embodiment of the quick-release ladder stabilizer and leveler. 
           [0018]      FIG. 6  illustrates a rear perspective exploded view of an embodiment of the quick-release ladder stabilizer and leveler. 
           [0019]      FIG. 7  illustrates a front elevation of an embodiment of the lightweight quick-release ladder stabilizer and leveler with attached ladder on inclined ground surface. 
           [0020]      FIG. 8  illustrates a side elevation of an embodiment of the lightweight quick-release ladder stabilizer and leveler with attached ladder. 
           [0021]      FIG. 9  illustrates a front elevation of an embodiment of the lightweight quick-release ladder stabilizer and leveler with attached ladder. 
           [0022]      FIG. 10  illustrates a rear elevation of an embodiment of the lightweight quick-release ladder stabilizer and leveler with attached ladder. 
           [0023]      FIG. 11  illustrates a front perspective exploded view of an embodiment of the lightweight quick-release ladder stabilizer and leveler. 
           [0024]      FIG. 12  illustrates a rear perspective exploded view of an embodiment of the lightweight quick-release ladder stabilizer and leveler. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    A. Quick-Release Ladder Stabilizer and Leveler 
         [0026]    A.1. First Embodiment 
         [0027]    A first embodiment of the quick-release ladder stabilizer and leveler  100  is shown in  FIGS. 1-6 . 
         [0028]    The base assembly  110  is a rigid truss-like structure  112  formed from aluminum alloy sheeting with cutouts and flanges. The base assembly  110  provides a strong support for the ladder harness assembly  170 , which is attached to the base assembly  110  by a ladder harness pivot  186 . The weight of the ladder  200  and its load are transferred from the ladder harness assembly  170  to the base assembly  110  via the ladder harness pivot  186 . The ladder harness locking mechanism cutout at the top of the base assembly  110  limits the rotation of the ladder harness assembly  170  to within a 60 degree range. 
         [0029]    The leg assemblies  130  and  150  include leg struts  132  and  152 , leg strut fasteners  146  and  148 , feet  134 , foot pivots  140 , foot pivot retainers  142 , foot pads  136 , and foot pad fasteners  138 . The leg assemblies  130  and  150  are constructed of steel, with the exception of the foot pads  136  which are rubber. The feet  134  have a serrated edge  144  to provide additional grip when the quick-release ladder stabilizer and leveler  100  is mounted on soft surfaces. The leg struts  132  and  152  are riveted to the base assembly  110  and provide a stable footing for the base assembly  110 . The distance between the feet  134  is approximately twice the width of the ladder  200 . Since the center of gravity of the ladder load must extend beyond the feet  134  before the ladder  200  can fall, the quick-release ladder stabilizer and leveler  100  provides a high degree of stability to the ladder  200 . 
         [0030]    The ladder harness assembly  170  includes a back-plate  172 , an upper rung bracket  199 , lower rung retainer  164 , ladder harness pivot  186 , and ladder harness pivot fasteners  184 ,  182 ,  124 ,  122 ,  120 ,  118 , and  116 . The back-plate  172  and upper rung bracket  199  are constructed out of a single piece of formed aluminum alloy sheeting. The lower rung retainer channel  176  is constructed of aluminum alloy. The other lower rung retainer components  178 ,  192 ,  193 ,  194 , and  195 , ladder harness pivot  186 , and ladder harness pivot fasteners  184 ,  182 ,  124 ,  122 ,  120 ,  118 , and  116  are constructed of steel. The ladder harness assembly  170  is pivotally attached to the base assembly  110  by a ladder harness pivot  186  and ladder harness pivot fasteners  184 ,  182 ,  124 ,  122 ,  120 ,  118 , and  116 . The rotatable ladder harness assembly  170 , to which the ladder  200  is removably attached, permits rapid leveling of the ladder  200  on a variety of surface inclines or footing levels. The bubble level  188 , retained between bubble level plates  190  and secured with bubble level fasteners  191 , serves as an aid for leveling the ladder  200 . 
         [0031]    Several components of the ladder harness assembly  170  support or laterally retain the ladder  200 ; however, actual securement/release of the ladder  200  is implemented by the lower rung retainer  164 . The lower rung retainer  164  comprises a wire clip  178 , lower rung retainer channel  176 , cotter pins  192 , and cables  193 . The ends of the wire clip  178  are inserted into flange mount holes in the back-plate  172  and are secured using wire clip fasteners  194 . The lower rung retainer channel  176  is attached to the back-plate  172  using lower rung retainer fasteners  195 . The cotter pins  192  are attached to the wire clip  178  by the cables  193 . The wire clip  178  is rotated down and over the first rung of the ladder  200  and is secured in the lower rung retainer channel  176  by the cotter pins  192 . Once the wire clip  178  is secured, the first rung of the ladder  200  is retained laterally between the wire clip  178  and the back-plate  172 ; the second rung of the ladder  200  is laterally retained between the top lip of the upper rung bracket  199  and the back-plate  172 . The weight of the ladder  200  and its load is supported by the upper rung bracket  199 . Once the wire clip  178  is released the ladder  200  can be removed by lifting the second rung of the ladder  200  over the top lip of the upper rung bracket  199 . Thus the quick-release ladder stabilizer and leveler  100  can be readily used with different ladders as the need arises. Furthermore, ease of separation of the ladder  200  from the quick-release ladder stabilizer and leveler  100  facilitates portability of both. 
         [0032]    The base assembly retainer lip  160 , extending from the plunger support bracket  174 , overlaps a far-side portion of the base assembly  110  so as to maintain close proximity between the ladder harness assembly  170  and the base assembly  110 . In this way, the base assembly retainer lip  160  maintains the coplanarity of the ladder harness assembly  170  and base assembly  110  under any ladder load or rotational position of the ladder harness assembly  170 , thus relieving stress on the ladder harness pivot  186 . 
         [0033]    The ladder harness locking mechanism  180 ,  174 , and  114  comprises a spring-loaded plunger  180 , plunger support bracket  174 , and locking plate  114 . The spring-loaded plunger  180 , plunger support bracket  174 , and locking plate  114  are constructed of steel. The plunger support bracket  174  is attached to the ladder harness assembly  170  using plunger support bracket fasteners  196  and  198 . The spring-loaded plunger  180  is housed within the plunger support bracket  174 . The locking plate  114  is attached to the base assembly  110  using locking plate fasteners  126  and  128 . The locking plate  114  has multiple slots for capturing the retractable end of the spring-loaded plunger  180 , and the retractable end of the spring-loaded plunger  180  is by default extended to engage with the slots in the locking plate  114 . The locking mechanism is disengaged by pulling the knob of the spring-loaded plunger  180  against internal spring resistance. The ladder harness locking mechanism  180 ,  174 , and  114  is designed to allow the ladder harness assembly  170  to lock at specific angles in order to hold the rails of the ladder  200  in a vertical orientation. Additionally, the ladder harness locking mechanism  180 ,  174 , and  114  is a positive locking mechanism that resists accidental disengagement due to vibration or rotational torque of the ladder harness assembly  170 . Furthermore, the ladder harness locking mechanism  180 ,  174 , and  114  can be engaged and disengaged single-handedly and rapidly without the aid of tools, permitting fast leveling of the ladder  200  by a single user. 
         [0034]    The overlapping open space within the base assembly  110  and ladder harness assembly  170  respectively permits a ladder user&#39;s foot to be placed on the first rung of the ladder  200  without significant obstruction. Unimpeded and normal placement of a user&#39;s foot on top of the central  12  inches of the first rung of the ladder  200  is provided. The top surface of the second rung of the ladder  200  clears the top of the upper rung bracket  199  and therefore placement of a user&#39;s foot on that rung or any subsequent rung is entirely unimpeded. Since use of the quick-release ladder stabilizer and leveler  100  with the ladder  200  does not alter the stepping distance between the first and second rungs of the ladder  200 , ANSI/OSHA requirements regarding rung spacing are met. Furthermore, since use of the quick-release ladder stabilizer and leveler  100  on level ground does not elevate the height of the first rung above fourteen inches from the ground, ANSI/OSHA ladder requirements regarding first rung height are met. Indeed, the quick-release ladder stabilizer and leveler  100  meets or exceeds all relevant ANSI A14 ladder requirements for ladder types III through IA. 
         [0035]    As a result of the foregoing, stability and vertical rail orientation of ladder  200  can be achieved on a variety of ground surfaces and inclines by placing the base assembly  110  on a ground surface, mounting the ladder  200  onto the ladder harness assembly  170 , rotating the ladder harness assembly  170  to achieve vertical ladder rail orientation, and locking the ladder harness assembly  170  to maintain vertical ladder rail orientation. 
         [0036]    The quick-release ladder stabilizer and leveler  100  of the aforementioned embodiment fits aluminum and fiberglass extension ladders of lengths up to 32 feet, encompassing approximately ninety percent of commercial extension ladders. 
         [0037]    A.2. Alternate Embodiments 
         [0038]    Alternative embodiments of the quick-release ladder stabilizer and leveler  100  include use of various materials or combinations of materials, such as aluminum, magnesium, or titanium, or alloys of the foregoing. 
         [0039]    Alternate embodiments of the base assembly  110  include base assemblies of various widths to meet other size and stability requirements. Several other structural configurations, such as trusses or arches, are possible without departing from the spirit of the disclosed embodiments. 
         [0040]    Alternative embodiments of the leg assemblies include telescoping feet in order to provide ladder stability and leveling on steps. Various feet shapes or forms, such as circular, non-pivoting, with holes to permit staking, or custom formed for particular applications are possible without departing from the spirit of the disclosed embodiments. 
         [0041]    Alternative embodiments of the lower rung retainer  364  use a differently formed wire clip  178  to suit various types of ladder rungs, or a wire clip  178  with a non-slip coating on its upper surface above the first rung. 
         [0042]    Alternative embodiments of the lower rung retainer  364  retain the first rung of the ladder  200  in a horizontally oriented lower rung retaining channel attached to the bottom plate  372  so as to enclose the back, top and bottom surfaces of the first rung of a ladder. A channel locking pin is inserted through a hole in the lower rung retaining channel in front of the first rung in order to retain it in the lower rung retaining channel. 
         [0043]    B. Lightweight Quick-Release Ladder Stabilizer and Leveler 
         [0044]    B.1. First Embodiment 
         [0045]    A first embodiment of the lightweight quick-release ladder stabilizer and leveler  300  is shown in  FIGS. 7-12 . 
         [0046]    The base assembly  310  comprises an arched member  312 , cross-brace  324 , and ladder harness stops  322 . The arched member  312  and cross-brace  324  are constructed of extruded aluminum alloy tubing. The arched member  312  comprises an arch section and two straight sections, one at each end of the arch section. The cross-brace  324  supports the ladder harness pivot  386 , however the weight of the ladder  400  and its load are transferred from the ladder harness assembly  370  via the bushing  382  to the arched member  312 . The substantially arched shape of the arched member  312  provides a strong and lightweight support for the ladder harness assembly  370 . The ladder harness stops  322  limit the rotation of the ladder harness assembly  370  to within a 90 degree range. 
         [0047]    The leg assemblies  330  and  350  comprise leg struts  332 , foot brackets  333 , cross-directional pivot components  340 ,  341 ,  342 ,  343 ,  344 ,  345 ,  346 ,  347 , and  348 , feet  334 , foot pads  336 , foot pad fasteners  338 , and locking pins  349 . The leg struts  332  are constructed of extruded aluminum alloy tubing. The foot brackets  333  and feet  334  are constructed of aluminum alloy. The foot pads  336  are rubber. The cross-directional pivot components  340 ,  341 ,  342 ,  343 ,  344 ,  345 ,  346 ,  347 , and  348 , foot pad fasteners  338 , and the locking pins  349 , are constructed of steel. The cross-directional pivots allow the feet  334  to swivel to match any surface incline. The leg struts  332  insert into the straight sections of the arched member  312  and provide a stable footing for the base assembly  310 . The extended/retracted position of the feet  334  can be rapidly and easily adjusted/secured through use of the locking pins  349 . The distance between the feet  334  (when retracted) is approximately twice the width of the ladder  400 . Since the center of gravity of the ladder load must extend beyond the feet  334  before the ladder  400  can fall, the lightweight quick-release ladder stabilizer and leveler  300  provides a high degree of stability to the ladder  400 . 
         [0048]    The ladder harness assembly  370  comprises a upper rung bracket  399 , bushing components  382  and  396 , sidebars  354 , bottom plate  372 , lower rung retainer  364 , ladder harness pivot  386 , and ladder harness pivot fasteners  384 ,  320 ,  318 , and  316 . The sidebars  354  are constructed of extruded aluminum alloy tubing. The upper rung bracket  399  and bottom plate  372  are constructed of formed aluminum alloy sheeting. The lower rung retainer  364 , ladder harness pivot  386 , and ladder harness pivot fasteners  384 ,  320 ,  318 , and  316  are constructed of steel. The bushing  382  is constructed of nylon. The ladder harness assembly  370  is pivotally attached to the base assembly  310  by the ladder harness pivot  386  and ladder harness pivot fasteners  384 ,  320 ,  318 , and  316 . The ladder harness pivot  386  passes through a vertically oriented oblong hole in the bottom plate  372 , such that the weight of the ladder  400  and its load are not transferred from the ladder harness assembly  370  to the cross-brace  324 . The oblong hole also permits the ladder harness assembly  370  and bushing  382  to be raised slightly, thus assisting in rotation of ladder harness assembly  370  by reducing friction between the bushing  382  and the arched member  312 . The rotatable ladder harness assembly  370 , to which the ladder  400  is attached, permits rapid leveling of the ladder  400  on a variety of surface inclines or footing levels. 
         [0049]    Several components of the lightweight quick-release ladder stabilizer and leveler  300  support or laterally retain the ladder  400 ; however, actual securement/release of the ladder  400  is implemented by the lower rung retainer  364 . The lower rung retainer  364  comprises a wire clip  378  and a latch  376 , which is a gate-type latch. The ends of the wire clip  378  are mounted in the sidebars  354 . The latch  376  is attached to the bottom plate  372  using latch fasteners  388 . The wire clip  378  is rotated down and over the first rung of the ladder  400  and is secured by the latch  376 . Once the wire clip  378  is secured, the first rung of the ladder  400  is laterally retained between the wire clip  378  and the sidebars  354  and the second rung of the ladder  400  is laterally retained between the upper rung bracket  399  and the arched member  312 . The weight of the ladder  400  and its load is supported by the upper rung bracket  399 . Once the wire clip  378  is released the ladder  400  can be removed by lifting the second rung of the ladder  400  over the top lip of the upper rung bracket  399 . Thus the lightweight quick-release ladder stabilizer and leveler  300  can be readily used with different ladders as the need arises. Furthermore, ease of separation of the ladder  400  from the lightweight quick-release ladder stabilizer and leveler  300  facilitates portability of both. 
         [0050]    The base assembly retaining lip  360 , extending from the upper rung bracket  399 , overlaps a far-side portion of the arched member  312  so as to maintain close proximity between the ladder harness assembly  370  and the base assembly  310 . In this way, the base assembly retaining lip  360  maintains the coplanarity of the ladder harness assembly  370  and base assembly  310  under any ladder load or rotational position of the ladder harness assembly  370 , thus relieving stress on the ladder harness pivot  386 . 
         [0051]    The ladder harness locking mechanism  380 ,  374 , and  314  comprises a spring-loaded plunger  380 , plunger support bracket  374 , and locking plate  314 . The spring-loaded plunger  380 , plunger support bracket  374 , and locking plate  314  are constructed of steel. The plunger support bracket  374  is attached to the ladder harness assembly  370  using plunger support bracket fasteners  390 ,  392 , and  394 . The spring-loaded plunger  380  is housed within the plunger support bracket  374 . The locking plate  314  is attached to the arched member  312  using locking plate fasteners  326 . The locking plate  314  has multiple slots for capturing the retractable end of the spring-loaded plunger  380 , and the retractable end of the spring-loaded plunger  380  is by default extended to engage with the slots in the locking plate  314 . The locking mechanism is disengaged by pulling the knob of the spring-loaded plunger  380  against internal spring resistance. The ladder harness locking mechanism  380 ,  374 , and  314  is designed to allow the ladder harness assembly  370  to lock at specific angles in order to hold the rails of the ladder  400  in a vertical orientation. Additionally, the ladder harness locking mechanism  380 ,  374 , and  314  is a positive locking mechanism that resists accidental disengagement due to vibration or rotational torque of the ladder harness assembly  370 . Furthermore, the ladder harness locking mechanism  380 ,  374 , and  314  can be engaged and disengaged single-handedly and rapidly without the aid of tools, permitting fast leveling of the ladder  400  by a single user. 
         [0052]    The overlapping open space within the base assembly  310  and ladder harness assembly  370  respectively permits a ladder user&#39;s foot to be placed on the first rung of the ladder  400  without significant obstruction. Unimpeded and normal placement of a user&#39;s foot on top of the central nine inches of the first rung of the ladder  400  is provided. The top surface of the second rung of the ladder  400  clears the top of the upper rung bracket  399  and therefore placement of a user&#39;s foot on that rung or any subsequent rung is entirely unimpeded. Since use of the lightweight quick-release ladder stabilizer and leveler  300  with the ladder  400  does not alter the stepping distance between the first and second rungs of the ladder  400 , ANSI/OSHA requirements regarding rung spacing are met. Furthermore, since use of the lightweight quick-release ladder stabilizer and leveler  300  on level ground does not elevate the height of the first rung above fourteen inches from the ground, ANSI/OSHA ladder requirements regarding first rung height are met. Indeed, the lightweight quick-release ladder stabilizer and leveler  300  meets or exceeds all relevant ANSI A14 ladder requirements for ladder types III through IA. 
         [0053]    As a result of the foregoing, stability and vertical rail orientation of ladder  400  can be achieved on a variety of ground surfaces and inclines by placing the base assembly  310  on a ground surface, mounting the ladder  400  onto the ladder harness assembly  370 , rotating the ladder harness assembly  370  to achieve vertical ladder rail orientation, and locking the ladder harness assembly  370  to maintain vertical ladder rail orientation. Furthermore, the lightweight quick-release ladder stabilizer and leveler  300  is suited for use on stairways, an example of which is shown in  FIG. 7 . By extending the downstairs-side foot  334 , the rotation of the ladder harness assembly  370  required to level the ladder  400  is reduced. This permits both feet  334  of the lightweight quick-release ladder stabilizer and leveler  300  to stand outside the rails of the ladder  400 , thereby increasing the stability of the ladder  400 . 
         [0054]    The lightweight quick-release ladder stabilizer and leveler  300  of the aforementioned embodiment fits aluminum and fiberglass extension ladders of lengths up to 32 feet, encompassing approximately ninety percent of commercial extension ladders. 
         [0055]    B.2. Alternate Embodiments 
         [0056]    Alternative embodiments of the lightweight quick-release ladder stabilizer and leveler  300  include use of various materials or combinations of materials, such as aluminum, magnesium, or titanium, or alloys of the foregoing. 
         [0057]    Alternate embodiments of the base assembly  310  include base assemblies of various widths to meet other size and stability requirements. Several other structural configurations, such as trusses or arches, are possible without departing from the spirit of the disclosed embodiments. 
         [0058]    Alternative embodiments of the leg assemblies  330  and  350  include fixed non-telescoping feet. Various feet  334  shapes or forms, such as circular, non-pivoting, with holes to permit staking, or custom formed for particular applications are possible without departing from the spirit of the disclosed embodiments. 
         [0059]    Alternative embodiments of the ladder harness assembly  370  include sidebars  354  spaced apart so that they  354  are directly behind the ladder  400  rails, or spaced wider than the rails. 
         [0060]    Alternative embodiments of the lower rung retainer  364  use a differently formed wire clip  378  to suit various types of ladder rungs, or a wire clip  378  with a non-slip coating on its upper surface above the first rung. 
         [0061]    Alternative embodiments of the lower rung retainer  364  retain the first rung of the ladder  400  in a horizontally oriented lower rung retaining channel attached to the bottom plate  372  so as to enclose the back, top and bottom surfaces of the first rung of a ladder. A channel locking pin is inserted through a hole in the lower rung retaining channel in front of the first rung in order to retain it in the lower rung retaining channel. 
         [0062]    Alternative embodiments of the lower rung retainer  364  retain the first rung of the ladder  400  using a locking rod inserted through the hollow first rung and secured at each end to brackets attached to the bottom plate  372 . In one such embodiment, the sidebars  354  are spaced apart so that they are directly behind the ladder  400  rails, and consequently placement of a user&#39;s foot on the first rung (and all subsequent rungs) of the ladder  400  is completely unimpeded. 
         [0063]    While particular embodiments have been described, it is understood that, after learning the teachings contained in this disclosure, modifications and generalizations will be apparent to those skilled in the art without departing from the spirit of the disclosed embodiments. It is noted that the foregoing embodiments and examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting. While the apparatus has been described with reference to various embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Further, although the apparatus has been described herein with reference to particular means, materials and embodiments, the actual embodiments are not intended to be limited to the particulars disclosed herein; rather, the system extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. Those skilled in the art, having the benefit of the teachings of this specification, may effect numerous modifications thereto and changes may be made without departing from the scope and spirit of the disclosed embodiments in its aspects.