Patent Publication Number: US-2021180403-A1

Title: Ladder Stiffener

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to ladders and, in some embodiments, to stiffening systems for ladders. Ladders are known in the art and are often used to reach elevated positions. As ladders increase in length, they tend to become less stable. Ladders can experience deflections, for example due to the weight of a user on the ladder. Ladders can also experience oscillations, for example caused by shifting or oscillating loads such as a user climbing the ladder. Deflections and oscillations are undesirable and can be unnerving for a user. 
     There remains a need for ladders having novel designs that provide for increased stiffness. There remains a need for devices that can be added to an existing ladder to increase the stiffness of the ladder. 
     All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety. 
     Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below. 
     A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims. 
     BRIEF SUMMARY OF THE INVENTION 
     In some embodiments, a stiffener system is arranged to attach to a ladder and comprises an arm and a cable. The cable comprises a first engagement portion arranged to engage the ladder at a first cable attachment location and a second engagement portion arranged to engage the ladder at a second cable attachment location. The cable comprises an adjustment mechanism arranged to move the second engagement portion along a length of the cable. The cable is arranged to contact the arm. The arm is arranged to engage the ladder at an attachment location between the first cable attachment location and the second cable attachment location. The arm is oriented at a non-zero angle to an orthogonal axis of the ladder. 
     In some embodiments, the cable comprises an end portion that extends past the second engagement portion, and the end portion comprises a handle. In some embodiments, the adjustment mechanism comprises a clamp arranged to engage the cable. 
     In some embodiments, the arm comprises a clamp arranged to fixedly engage the ladder. 
     In some embodiments, the arm comprises a protrusion arranged to extend into a ladder rung. 
     In some embodiments, the arm comprises a first leg and a second leg. The first leg comprises a first protrusion arranged to extend into a first ladder rung and the second leg comprises a second protrusion arranged to extend into a second ladder rung. 
     In some embodiments, the arm comprises an articulating portion arranged for attachment to the ladder. In some embodiments, the articulating portion comprises an articulating bracket. In some embodiments, the articulating portion allows the arm to be moved and reoriented with respect to the ladder. 
     In some embodiments, the arm comprises a guide member arranged to engage the cable. The guide member comprises a first hook oriented in a first direction and a second hook oriented in a second direction. 
     In some embodiments, the stiffener system comprises a bracket arranged to attach to the ladder. The cable comprises a connector arranged to engage the bracket. In some embodiments, the bracket comprises a shaped aperture and the connector comprises a protrusion comprising a key. The protrusion is positionable in the shaped aperture. The cable comprises a locked orientation wherein the key cannot exit the shaped aperture and a disengagable orientation wherein the key can pass through the shaped aperture. In some embodiments, the connector comprises an engagement mechanism having a first orientation and a second orientation. In the first orientation, the connector is moveable along a length of the cable and in the second orientation, the connector is fixed along the length of the cable. 
     In some embodiments, the ladder comprises a first ladder portion arranged to move with respect to a second ladder portion and the stiffener system further comprises a lock mechanism arranged to attach to the second ladder portion. The lock mechanism comprises a lock member arranged to move with respect to the second ladder portion. The lock member comprises a contacting surface arranged to contact the first ladder portion. 
     In some embodiments, a stiffener system is arranged for attachment to a ladder. In some embodiments, the ladder comprises a first rail, a second rail and a plurality of rungs extending between the first rail and the second rail, and defines a longitudinal axis, a lateral axis and an orthogonal axis. In some embodiments, the stiffener system comprises a first stiffener and a second stiffener. The first stiffener comprises a first arm and a first cable. The first arm is attached to the first rail. The first cable is attached to the first rail at a first cable upper attachment location, extends to contact the first arm and extends to attach to the first rail at a first cable lower attachment location. The second stiffener comprises a second arm and a second cable. The second arm is attached to the second rail. The second cable is attached to the second rail at a second cable upper attachment location, extends to contact the second arm and extends to attach to the second rail at a second cable lower attachment location. The first arm is oriented at a non-zero angle to the orthogonal axis and the second arm is oriented at a non-zero angle to the orthogonal axis. 
     In some embodiments, the first arm and the second arm are arranged for orientation at equal-but-opposite angles to a portion of the ladder. 
     In some embodiments, the first cable comprises an end portion extending past the first cable lower attachment location. 
     In some embodiments, the first cable comprises an adjustment mechanism arranged to adjust a length portion of the first cable located between the first cable upper attachment location and the first cable lower attachment location. In some embodiments, the second cable comprises an adjustment mechanism. 
     In some embodiments, an adjustment mechanism surrounds the first cable and is moveable along the length of the first cable. In some embodiments, the adjustment mechanism comprises a clamp. 
     In some embodiments, the first arm comprises a first protrusion arranged for orientation in a first rung. In some embodiments, the first protrusion is arranged to extend through the first rail. In some embodiments, the second arm comprises a second arm protrusion arranged for orientation in the first rung. In some embodiments, the second arm protrusion is arranged to extend through the second rail. In some embodiments, the first arm further comprises a second protrusion arranged for orientation in a second rung. 
     In some embodiments, the stiffener system comprises a bracket arranged for attachment to the ladder. The bracket comprises a shaped aperture. The first cable comprises a protrusion comprising a key. The protrusion is positionable in the shaped aperture. The first cable has a locked orientation wherein the key cannot exit the shaped aperture and a disengagable orientation wherein the key can pass through the shaped aperture. 
     In some embodiments, the first arm comprises an articulating bracket arranged for attachment to the ladder. In some embodiments, the articulating bracket allows the first arm to pivot with respect to the ladder about a first axis. In some embodiments, the articulating bracket further allows the first arm to pivot with respect to the ladder about a second axis. In some embodiments, the second axis is orthogonal to the first axis. 
     In some embodiments, the first arm comprises a clamp arranged to engage the ladder. In some embodiments, the clamp is arranged to fixedly engage the ladder, for example forming a moment transmitting attachment. In some embodiments, the clamp is arranged to fixedly engage a rail of the ladder. In some embodiments, a clamp comprises an open position and a closed position. In the open position, the arm is or can be disengaged from the ladder, and in the closed position, the arm is fixedly engaged with the ladder. 
     In some embodiments, a stiffener system is arranged for attachment to a ladder. In some embodiments, the ladder comprises a first ladder portion arranged to move with respect to a second ladder portion. In some embodiments, the first ladder portion comprises a rung and the second ladder portion comprises a rail. In some embodiments, stiffener system comprises an arm, a cable and a lock mechanism. The arm is arranged to attach to the ladder at an arm attachment location. The cable is arranged to attach to the ladder at a first location, extend to engage the arm and extend to attach to the ladder at a second location. The lock mechanism is arranged to attach to the second ladder portion. The lock mechanism comprises a lock member arranged to move with respect to the second ladder portion. The lock member comprises a contacting surface arranged to contact the first ladder portion. In some embodiments, the lock mechanism is arranged to attach to the rail and the contacting surface is arranged to contact the rung. 
     In some embodiments, a ladder comprises a first rail, a second rail and a plurality of rungs extending between the first rail and the second rail. A first stiffener comprises a first arm and a first cable. The first arm is attached to the first rail. The first cable is attached to the first rail at a first cable upper attachment location, extends to contact the first arm and extends to attach to the first rail at a first cable lower attachment location. A second stiffener comprises a second arm and a second cable. The second arm is attached to the second rail. The second cable is attached to the second rail at a second cable upper attachment location, extends to contact the second arm and extends to attach to the second rail at a second cable lower attachment location. The ladder comprises a longitudinal axis, a lateral axis and an orthogonal axis. The first arm is oriented at a non-zero angle to the orthogonal axis and the second arm is oriented at a non-zero angle to the orthogonal axis. 
     In some embodiments, the first arm and the second arm are oriented at equal-but-opposite angles to the orthogonal axis. 
     In some embodiments, the first cable comprises an end portion extending past the first cable lower attachment location. 
     In some embodiments, the first cable comprises an adjustment mechanism arranged to adjust a length portion of the first cable located between the first cable upper attachment location and the first cable lower attachment location. In some embodiments, the second cable comprises an adjustment mechanism. 
     In some embodiments, an adjustment mechanism surrounds the first cable and is moveable along the length of the first cable. In some embodiments, the adjustment mechanism comprises a clamp. 
     In some embodiments, the first arm comprises a first protrusion oriented in a first rung. In some embodiments, the first protrusion extends through the first rail. In some embodiments, the second arm comprises a second arm protrusion oriented in the first rung. In some embodiments, the second arm protrusion extends through the second rail. In some embodiments, the first arm further comprises a second protrusion oriented in the second rung. 
     In some embodiments, the first rail comprises a shaped aperture and the first cable comprises a protrusion comprising a key. The protrusion is positionable in the shaped aperture. The first cable has a locked orientation wherein the key cannot exit the shaped aperture and a disengagable orientation wherein the key can pass through the shaped aperture. 
     In some embodiments, the first stiffener is disengageble from the first rail. 
     In some embodiments, the first arm is repositionable with respect to the first rail between a stowed orientation and a deployed orientation. 
     In some embodiments, the first arm comprises a cable guide comprising a guide passageway, the first cable oriented in the guide passageway. In some embodiments, the first cable comprises a first orientation when under tension, the first cable unable to exit the guide passageway in the first orientation. In some embodiments, the first cable is positionable to a second orientation wherein the first cable can exit the guide passageway. 
     In some embodiments, the cable guide comprises a first hook and a second hook, the first hook and the second hook facing different directions. In some embodiments, the first hook and the second hook are separated by a gap. In some embodiments, the guide passageway passes through the first hook and the second hook. In some embodiments, an insertion passageway is located between the first hook and the second hook. 
     In some embodiments, the ladder comprises a first portion and a second portion moveable with respect to the first portion. In some embodiments, the first portion is arranged to slide along an axis with respect to the second portion. In some embodiments, the first portion is arranged to rotate about an axis with respect to the second portion. In some embodiments, the first portion comprises the first cable lower attachment location and the second portion comprises the first cable upper attachment location. In some embodiments, the first arm comprises a first leg and a second leg, the first leg attached to the second portion, the second leg attached to the first portion. 
     In some embodiments, a ladder comprises a lock mechanism arranged to lock the first portion against moving with respect to the second portion. In some embodiments, the lock mechanism is attached to the second portion and a lock member is moveable with respect to the second portion. In some embodiments, the lock member comprises a contacting surface that contacts the first portion. In some embodiments, the contacting surface comprises a camming surface. 
     In some embodiments, the first arm is moveable with respect to the first rail between a deployed orientation and a stowed orientation. In some embodiments, the first arm comprises a storage bracket for storing the first cable. In some embodiments, the first rail comprises a clip arranged to engage the first arm and retain the first arm in a stowed orientation. 
     In some embodiments, a ladder comprises a positioner arranged to position the first arm in the deployed orientation. In some embodiments, a central axis of the first arm is orthogonal to a longitudinal axis of the ladder in the deployed orientation. 
     In some embodiments, the first arm comprises a clamp arranged to engage the first rail. In some embodiments, the arm is disengageable from the first rail by disengaging the clamp. 
     In some embodiments, a ladder further comprises a cross-brace extending between the first arm and the second arm. 
     In some embodiments, a ladder comprises a first rail, a second rail and a plurality of rungs extending between the first rail and the second rail. A first stiffener comprises a first arm and a first cable. The first arm is attached to the first rail. The first cable is attached to the first rail at a first cable upper attachment location. The first cable contacts the first arm at a first contact point. The first cable is also attached to the first rail at a first cable lower attachment location. A second stiffener comprises a second arm and a second cable. The second arm is attached to the second rail. The second cable is attached to the second rail at a second cable upper attachment location. The second cable contacts the second arm at a second contact point. The second cable is also attached to the second rail at a second cable lower attachment location. A distance between the first contact point and the second contact point is greater than a distance between the first rail and the second rail. 
     In some embodiments, a ladder comprises a first rail, a second rail and a plurality of rungs extending between the first rail and the second rail. A stiffener comprises an arm and a cable. The arm is attached to the first rail and comprises a guide member comprising a first hook and a second hook defining a guide passageway. The cable is attached to the first rail at an upper attachment location. A portion of the cable is oriented in the guide passageway and contacting the guide member. The cable is also attached to the first rail at a lower attachment location. 
     In some embodiments, the guide member defines an insertion passageway in fluid communication with the guide passageway. In some embodiments, a central axis of the guide passageway is oriented at an angle to a central axis of the insertion passageway. In some embodiments, the insertion passageway is defined between the first hook and the second hook. 
     In some embodiments, the first hook is oriented in a first direction and the second hook oriented in a second direction different from the first direction. In some embodiments, the first hook and the second hook face opposite directions. 
     In some embodiments, the guide member comprises a cable seat and the cable seat comprises curvature. 
     In some embodiments, a ladder stiffener comprises an arm and a cable. The cable comprises a first engagement portion and a second engagement portion. The first engagement portion is arranged to engage the ladder at a first cable attachment location. The second engagement portion is arranged to engage the ladder at a second cable attachment location. The cable comprises an adjustment mechanism arranged to move the second engagement portion along a length of the cable. The cable is arranged to contact the arm. The arm is arranged to engage the ladder at an attachment location between the first cable attachment location and the second cable attachment location. 
     In some embodiments, the arm comprises a clamp arranged to engage the ladder. 
     In some embodiments, the arm comprises a protrusion arranged to extend into a ladder rung. In some embodiments, the arm comprises a second protrusion arranged to extend into a second ladder rung. 
     In some embodiments, the arm comprises a guide member comprising a first hook and a second hook defining a guide passageway. 
     In some embodiments, the first engagement portion comprises a bracket and a connector. In some embodiments, the bracket is attachable to the ladder, the connector is attached to the cable and the connector is arranged to engage the bracket. In some embodiments, the bracket comprises a shaped aperture and the connector comprises a complimentary shaped key. 
     In some embodiments, a method comprises providing a stiffener comprising an arm and a cable and attaching a first portion of the cable to a ladder at a first cable attachment location. A second portion of the cable is attached to the ladder at a second cable attachment location. The arm is attached to the ladder at a location between the first cable attachment location and the second cable attachment location. A length of the cable oriented between the first cable attachment location and the second cable attachment location is adjusted. 
     These and other embodiments which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objectives obtained by its use, reference can be made to the drawings which form a further part hereof and the accompanying descriptive matter, in which there are illustrated and described various embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A detailed description of the invention is hereafter described with specific reference being made to the drawings. 
         FIG. 1  shows an embodiment of a ladder and an embodiment of a stiffening system. 
         FIG. 2  shows a portion of an embodiment of a ladder. 
         FIG. 3  shows an exploded view of an embodiment of an attachment mechanism between a ladder and a cable. 
         FIG. 4  shows another embodiment of an attachment mechanism and an embodiment of an adjustment mechanism. 
         FIG. 5  shows a cross-sectional view of an embodiment of an attachment mechanism and an embodiment of an adjustment mechanism. 
         FIG. 6  shows the components shown in  FIG. 4  in a disengaged orientation. 
         FIG. 7  shows an embodiment of a stiffening system. 
         FIG. 8  shows an exploded view of the components shown in  FIG. 7 . 
         FIG. 9  shows an embodiment of a cable guide member. 
         FIG. 10  shows a top view of an embodiment of a ladder and stiffening system. 
         FIG. 11  shows an embodiment of a ladder and an embodiment of a lock mechanism. 
         FIG. 12  shows another embodiment of a ladder and an embodiment of a stiffening system. 
         FIG. 13  shows a portion of the ladder and stiffening system shown in  FIG. 12  in greater detail. 
         FIG. 14  shows another embodiment of a ladder and an embodiment of a stiffening system. 
         FIG. 15  shows a portion of the ladder and stiffening system shown in  FIG. 14  in greater detail. 
         FIG. 16  shows a connection between an embodiment of a ladder and an embodiment of a stiffening system. 
         FIG. 17  shows an embodiment of a stiffening system in a storage configuration. 
         FIG. 18  shows another embodiment of a ladder comprising an embodiment of a stiffening system. 
         FIG. 19  shows a portion of the ladder and stiffening system shown in  FIG. 18  in greater detail. 
         FIG. 20  shows an embodiment of a bracket. 
         FIG. 21  shows the ladder of  FIG. 18  with stiffeners in a storage configuration. 
         FIGS. 22 and 23  show embodiments of a lock mechanism. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
     For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated. 
       FIG. 1  shows an embodiment of a ladder  10  and an embodiment of a stiffener  50  for a ladder  10 . Desirably, the stiffener  50  is arranged to structurally reinforce the ladder  10 , for example making the ladder  10  stronger and reducing deflections of the ladder  10  under load. 
     In some embodiments, a ladder  10  comprises a first end  11  and a second end  12 . In some embodiments, the first end  11  is constructed and arranged to contact a supporting surface, such as the ground. In some embodiments, the second end  12  is constructed and arranged to extend in an upward direction relative to the first end  11 . 
     In some embodiments, a ladder  10  comprises a first rail  14  and a second rail  16 . In some embodiments, each rail  14 ,  16  extends an entire length of the ladder  10 . In some embodiments, a ladder  10  comprises a plurality of rungs  15 . In some embodiments, each rung  15  extends between the first rail  14  and the second rail  16 . 
     In some embodiments, a stiffener  50  comprises an arm  54  and a cable  66 . Desirably, the arm  54  is supported by the ladder  10 . In some embodiments, the arm  54  is attached to the ladder  10  at an arm attachment location  80 . The arm  54  can be supported by, or attached to, any suitable location of the ladder  10 . In some embodiments, the arm  54  is attached approximately midway between the first end  11  and the second end  12  of the ladder  10 , which tends to provide the greatest resistance to deflections of the ladder  10 . In some embodiments, the arm  54  is attached to the ladder  10  at a location in the middle third of the length of the ladder  10 . In some embodiments, the arm  54  is attached to a rail  14 ,  16  of the ladder  10 . In some embodiments, the arm  54  is attached to the first rail  14 . 
     In some embodiments, the cable  66  is attached to the ladder  10  at a first attachment location  70  and at a second attachment location  72 . In some embodiments, the cable  66  is engaged with the arm  54 . In some embodiments, the cable  66  contacts the arm  54  at a portion of the cable  66  located between the first attachment location  70  and the second attachment location  72 . In some embodiments, the first attachment location  70  and the second attachment location  72  are located on opposite sides of the arm attachment location  80 . In some embodiments, the first attachment location  70  is located between the arm attachment location  80  and the first end  11  of the ladder  10 . In some embodiments, the second attachment location  72  is located between the arm attachment location  80  and the second end  12  of the ladder  10 . In some embodiments, the arm  54  and cable  66  comprise a truss system that structurally reinforces the ladder  10 . In some embodiments, the cable  66  comprises a tension member and the arm  54  comprises a compression member. 
     In some embodiments, the arm  54  comprises a first arm  54  and the cable  66  comprises a first cable  66 , and the first arm  54  and first cable  66  comprise a first stiffener  50  engaged with the first rail  14 . 
     In some embodiments, a second stiffener  52  is provided. In some embodiments, the second stiffener  52  comprises a second arm  56  and a second cable  68 . Desirably, the second arm  56  is supported by the ladder  10 . In some embodiments, the second arm  56  is attached to the ladder  10  at a second arm attachment location  82 . In some embodiments, the second arm  56  is attached to the second rail  16 . In some embodiments, the second arm  56  is attached approximately midway between the first end  11  and the second end  12  of the ladder  10 . In some embodiments, positioning of the second arm attachment location  82  is similar to that of the first arm attachment location  80 . 
     In some embodiments, the second cable  68  is attached to the ladder  10  at a third attachment location  74  and at a fourth attachment location  76 . In some embodiments, the third attachment location  74  is aligned with the first attachment location  70 . In some embodiments, the fourth attachment location  76  is aligned with the second attachment location  72 . In some embodiments, the first arm attachment location  80  is aligned with the second arm attachment location  82 . In some embodiments, the first stiffener  50  and the second stiffener  52  are similar in size and shape but have opposite orientations. 
     In some embodiments, the first attachment location  70  comprises a first cable lower attachment location. In some embodiments, the second attachment location  72  comprises a first cable upper attachment location. In some embodiments, the third attachment location  74  comprises a second cable lower attachment location. In some embodiments, the fourth attachment location  76  comprises a second cable upper attachment location. 
     In some embodiments, a first stiffener  50  and a second stiffener  52  can be non-symmetrical with one another, for example being shaped differently and/or engaging locations of the ladder  10  that are not aligned with one another. 
       FIGS. 2 and 3  show an embodiment of an attachment mechanism  86  for attaching a cable  66 ,  68  to a rail  14 ,  16 . In some embodiments, the attachment mechanism  86  is arranged to provide a secure connection for a cable  66 ,  68  that will not detach under load. In some embodiments, the attachment mechanism  86  is constructed and arranged to allow the cable  66 ,  68  to be quickly and easily attached to, or disengaged from, a rail  14 ,  16  when the cable  66 ,  68  is not under load. 
     In some embodiments, an attachment mechanism  86  comprises a bracket  60  and a connector  62  arranged to engage the bracket  60 . In some embodiments, the bracket  60  is attachable to the ladder  10 . In some embodiments, a bracket  60  is fixedly attached to the ladder  10 . In some embodiments, a bracket  60  is fixedly attached to a rail  14 ,  16 . In some embodiments, the connector  62  is fixedly attached to a cable  66 ,  68 . In some embodiments, the bracket  60  comprises an aperture  61  and the connector  62  comprises a protrusion  63  arranged to extend through the aperture  61 . In some embodiments, the aperture  61  comprises a non-circular shape and the protrusion  63  comprises a key  64  comprising a complimentary shape. In some embodiments, the key  64  can only pass through the aperture  61  at one or more predetermined aligned orientations of the key  64  with respect to the aperture  61 , and the key  64  is unable to pass through the aperture  61  at other non-aligned orientations. Thus, in some embodiments, the cable  66  can be attached to the rail  14  by properly orienting the connector  62  with respect to the bracket  60  and moving the connector  62  such that its key  64  passes through the aperture  61 . In some embodiments, the connector  62  can then be rotated with respect to the bracket  60 , wherein the key  64  assumes a non-aligned orientation with respect to the aperture  61  and the connector  62  remains engaged with the bracket  60 . In some embodiments, the aligned orientation(s) that allow engagement/disengagement comprise positions that the cable  66  and connector  62  will not ordinarily assume when the stiffener  50  is in use. In some embodiments, when the cable  66  is engaged with the ladder  10  and the cable  66  is under tension, the key  64  remains in a non-aligned orientation and the connector  62  cannot detach from the bracket  60 . 
     In some embodiments, an attachment mechanism  86  can be used at any location that a cable  66 ,  68  engages the ladder  10 , such as the attachment locations  70 ,  72 ,  74 ,  76  discussed herein. In some embodiments, an attachment mechanism  86  is used at each location that a cable  66 ,  68  engages the ladder  10 . This allows the cable(s)  66 ,  68  to be quickly and easily engaged to the ladder  10  or disengaged from the ladder  10 . 
       FIGS. 4-6  show an embodiment of a cable  66 ,  68 , an embodiment of an adjustment mechanism  90  and another embodiment of an attachment mechanism  86 . 
     In some embodiments, a stiffener  50  comprises an adjustment mechanism  90  arranged to adjust the amount of cable  66  that is subject to tension when the stiffener  50  is installed on a ladder  10 . For example, in some embodiments, an adjustment mechanism  90  is arranged to adjust the portion of length of cable  66  that is subject to tension, such as the portion of cable  66  located between attachment mechanisms  86  at the related attachment locations  70 ,  72 . In some embodiments, an adjustment mechanism  90  is engageable to, and disengageable from, the cable  66 . In some embodiments, an adjust mechanism  90  comprises a first configuration wherein the position of the adjustment mechanism  90  is fixed along the length of the cable  66  and a second configuration wherein the adjustment mechanism  90  is moveable along the length of the cable  66 . 
       FIG. 5  shows a cross-sectional view of an embodiment of an adjustment mechanism  90 . In some embodiments, an adjustment mechanism  90  comprises an engagement mechanism  91  arranged to selectively engage or release the cable  68 . In some embodiments, an engagement mechanism  91  comprises a clamp  94 . In some embodiments, an engagement mechanism  91  comprises a first portion  92  and a second portion  93  moveable with respect to the first portion  92 . In some embodiments, the first portion  92  comprises a fixed portion that comprises a seat for the cable  68 . In some embodiments, the second portion  93  comprises a moveable jaw of the clamp  94  that can be tightened against the cable  68 . In some embodiments, the second portion  93  comprises a plunger that can be moved closer to, or farther away from, the first portion  92 . In some embodiments, a control mechanism is arranged to operate the second portion  93 . In some embodiments, a control mechanism comprises a threaded shaft  96  arranged to engage complimentary threads  108  in the adjustment mechanism  90 . In some embodiments, a knob  95  is provided to manually rotate the threaded shaft  96 , thereby tightening or loosening the engagement between the cable  68  and the engagement mechanism  91 . In some embodiments, a control mechanism comprises a quick-release arm that is moveable between a first position wherein the engagement mechanism  91  is fixed along the length of the cable  68  and a second position wherein the engagement mechanism  91  is not fixed along the length of the cable  68 . 
     In some embodiments, a connector  62  comprises a sleeve arranged to surround a cable  68 . In some embodiments, a connector  62  comprises an adjustment mechanism  90 . In some embodiments, a connector  62  comprises an engagement mechanism  91 . 
       FIG. 6  shows an embodiment of a connector  62  comprising an adjustment mechanism  90  and a protrusion  63  arranged to engage a bracket  60 . In some embodiments, a cable  68  comprises a handle  88 . In some embodiments, the handle  88  is attached to a portion  87  of the cable  68  that is located distal to the connector  62  along the length of the cable  68 . Thus, in some embodiments, the handle  88  is attached to a portion  87  of the cable  68  that is not under tension in the stiffener  50 . 
     In some embodiments, a first connector  62  of a cable  66  can be engaged with a rail  14  at a first attachment location  70  and a second connector  62  of the cable  66  can be engaged with the rail  14  at a second attachment location  72 . The handle  88  of the cable  66  can be used to manually apply a tensile load to the cable  66  and an engagement mechanism  91  can be arranged to engage the cable  66 , thereby retaining the cable  66  under the tensile load and stiffening a ladder against deflections. 
       FIG. 7  shows an embodiment of a first arm  54  and a second arm  56  attached to a ladder  10 .  FIG. 8  shows an exploded view of the components shown in  FIG. 7 . In some embodiments, the first arm  54  is attached to a first rail  14  and the second arm  56  is attached to the second rail  16 . In some embodiments, each arm  54 ,  56  comprises a compression member arranged to transmit compressive forces between the ladder  10  and an associated cable  66 ,  68 . 
     An arm  54 ,  56  can engage the ladder  10  using any suitable method. In some embodiments, an arm  54 ,  56  comprises a protrusion  48  arranged to be received by a portion of the ladder  10 . In some embodiments, a protrusion  48  is configured to be received by an interior portion of a rung  15  of the ladder  10 . In some embodiments, a ladder  10  comprises rungs  15  having a D-shaped cross-sectional shape or otherwise comprising a flattened top, and the protrusion  48  comprises a complimentary shape arranged to engage the rung  15 . In some embodiments, a protrusion  48  comprises a flat surface. In some embodiments, a protrusion  48  extends through a rail  14 ,  16  when positioned in a rung  15 . 
     In some embodiments, an arm  54 ,  56  comprises a first protrusion  48  and a second protrusion  48   b . In some embodiments, the first protrusion  48  is oriented in a first rung  15  and the second protrusion  48   b  is oriented in a second rung  15   b . In some embodiments, the first rung  15  is adjacent to the second rung  15   b  along the length of the ladder  10 . 
     In some embodiments, an arm  54 ,  56  comprises a first leg  58  and a second leg  59 . In some embodiments, the first leg  58  comprises a first protrusion  48  and the second leg  59  comprises a second protrusion  48   b . In some embodiments, an arm  54 ,  56  comprises a central axis  55 , and the first leg  58  is oriented at an angle to the central axis  55 . In some embodiments, the second leg is oriented at an angle to the central axis  55 . In some embodiments, the first leg  58  and the second leg  59  are oriented at equal but opposite angles to the central axis  55 . In some embodiments, the first leg  58  and the second leg  59  form an A-frame. 
     In some embodiments, a length of an arm  54 ,  56  can be adjusted. In some embodiments, an arm  54 ,  56  comprises a first portion  44  that is moveable with respect to a second portion  46 . In some embodiments, the first portion  44  is moveable along the central axis  55 . In some embodiments, an arm  54 ,  56  can be arranged to have a length selected from a plurality of predetermined length configurations. In some embodiments, an arm  54 ,  56  comprises a detent system comprising a plurality of detents  47  and an engagement mechanism  45  arranged to engage a detent  47 . In some embodiments, the detents  47  comprise apertures and the engagement mechanism  45  comprises a pin  45  arranged to be oriented in an aperture. In some embodiments, the engagement mechanism  45  fastens the first portion  44  to the second portion  46  and fixes a length of the arm  54 ,  56 . In some embodiments, a pin  45  extends through an aperture of the second portion  46  and through an aperture of the first portion  44 . In some embodiments, multiple detents  47  are spaced at regular intervals. 
     In some embodiments, an arm  54 ,  56  comprises a housing  57  arranged to attach multiple components of the arm  54 ,  56 . In some embodiments, a housing  57  comprises a first cavity arranged to receive a first portion  44  of the arm  54 ,  56 . In some embodiments, a second portion  46  of the arm  54 ,  56  comprises the housing  57  and the first portion  44  is moveable with respect to the housing  57 . In some embodiments, the first cavity comprises a non-circular cross-sectional shape, and the first portion  44  comprises a complimentary shape arranged to be received by the first cavity. In some embodiments, a central axis of the first cavity is parallel to a central axis  55  of the arm  54 ,  56 . In some embodiments, a central axis of the first cavity is collinear with the central axis  55  of the arm  54 ,  56 . In some embodiments, the housing  57  comprises a second cavity arranged to receive a first leg  58 . In some embodiments, the housing  57  comprises a third cavity arranged to receive a second leg  59 . In some embodiments, a central axis of each of the second cavity and the third cavity are oriented at equal but opposite angles with respect to the central axis of the first cavity. 
     In some embodiments, an arm  54 ,  56  comprises a guide member  38  arranged to engage a cable  66 ,  68 . 
       FIG. 9  shows an embodiment of a guide member  38  in greater detail. In some embodiments, a guide member  38  is located at an end of an arm  54 ,  56 . In some embodiments, a first end of an arm  54 ,  56  is attached to a ladder  10  and a second end of the arm  54 ,  56  comprises a guide member  38 . 
     In some embodiments, a guide member  38  comprises a guide passageway  41  that is arranged to contain a cable  66 ,  68 . In some embodiments, a guide passageway  41  extends substantially parallel to a length portion of the cable  66 ,  68  when the cable is arranged in an installed orientation. Desirably, the cable  66  is oriented in the guide passageway  41  in an installed orientation. In some embodiments, the guide member  38  is configured such that the cable  66  cannot exit the guide passageway  41  when the cable  66  is under tension in the installed orientation. 
     In some embodiments, a guide member  38  comprises a first hook  40  and a second hook  42 . In some embodiments, the first hook  40  is arranged to face a first direction and the second hook  42  is arranged to face a second direction that is different from the first direction. In some embodiments, the first hook  40  and the second hook  42  face opposite directions. In some embodiments, the first hook  40  comprises a base portion positioned to a first side of the guide passageway  41  and a bend that extends over the guide passageway  41 . In some embodiments, the bend extends to a second side of the guide passageway  41 . In some embodiments, the second hook  42  comprises a base portion positioned to a second side of the guide passageway  41  and a bend that extends over the guide passageway  41 . In some embodiments, the bend extends to the first side of the guide passageway  41 . In some embodiments, the first hook  40  and the second hook  42  each comprise a throat portion that defines the guide passageway  41 . In some embodiments, the first hook  40  prevents the cable  66  from exiting the guide passageway  41  on the first side and the second hook  42  prevents the cable  66  from exiting the guide passageway  41  on the second side when the cable  66  is under tension in the installed orientation. 
     In some embodiments, the guide member  38  comprises an insertion passageway  43  that allows the cable  66  to enter and exit the guide passageway  41 . In some embodiments, when the cable  66  is in a first orientation, it is unable to exit the guide passageway  41  or enter the insertion passageway  43 . In some embodiments, when the cable  66  is moved to a second orientation, the cable  66  is able to exit the guide passageway  41  and move through the insertion passageway  43 . In some embodiments, the cable  66  comprises the first orientation when the cable  66  is oriented in the guide passageway  41  under tension in the installed orientation. In some embodiments, when the cable  66  is not under load, a portion of the cable  66  can be arranged to the second orientation, wherein the cable can move though the insertion passageway  43  and disengage the guide member  38 . In some embodiments, the longitudinal axis of a segment of cable  66  in the first orientation is nonparallel to the longitudinal axis of the segment in the second orientation. 
     In some embodiments, the first hook  40  and the second hook  42  are spaced apart and separated by a gap. In some embodiments, the gap comprises the insertion passageway  43 . In some embodiments, a longitudinal axis of the guide passageway  41  is nonparallel to a longitudinal axis of the insertion passageway  43 . In some embodiments, a longitudinal axis of the guide passageway  41  is generally orthogonal to a longitudinal axis of the insertion passageway  43 . In some embodiments, portions of the cable  66  move through the gaps defined by the first hook  40  and second hook  42  as the cable  66  is repositioned from the first orientation to the second orientation. 
     In some embodiments, a guide member  38  comprises a seat  39  arranged to contact a cable  66 . In some embodiments, the seat  39  comprises a curved surface arranged to support the cable  66 . In some embodiments, the seat  39  comprises a first curvature arranged to provide contact along a lengthwise surface of the cable  66 . In some embodiments, the first curvature comprises a convex shape arranged to compliment a bend in the cable  66  when the cable  66  is installed on a ladder  10 . In some embodiments, the seat  39  comprises a second curvature arranged to provide contact along a circumferential outer surface of the cable  66 . In some embodiments, the second curvature comprises a concave shape that forms a valley that helps to position the cable  66 . In some embodiments, the first curvature is oriented about a first axis and the second curvature is oriented about a second axis that is non-parallel to the first axis. In some embodiments, the first curvature comprises a convex surface contoured around a first axis and the second curvature comprises a concave shape contoured around a second axis. In some embodiments, at least a portion of the first axis is oriented orthogonal to the second axis. 
       FIG. 10  shows a top view of an embodiment of a ladder  10  comprising a first stiffener  50  and a second stiffener  52 . In some embodiments, the stiffeners  50 ,  52  are arranged to splay outwardly away from one another, which can provide a greater stiffening effect for the ladder  10 . 
     The ladder  10  defines an axis in each of the three orthogonal dimensions including a longitudinal axis  21 , a lateral axis  22  and an orthogonal axis  23 . In various embodiments, the arms  54 ,  56  of the stiffeners  50 ,  52  can be oriented at any suitable angle with respect to the lateral axis  22  and with respect to the orthogonal axis  23 . Various orientations of the arms  54 ,  56 , and the related locations of contact points between the cables  66 ,  68  and the arms  54 ,  56  and ladder rails  14 ,  16 , will provide the ladder  10  with varying amounts of resistance to deformations along the orthogonal axis  23  and/or the lateral axis  22 . As a user climbs the ladder  10 , the loads on the ladder  10  can cause deformation and oscillation of a midportion of the ladder  10  in directions orthogonal to the longitudinal axis  21 . For example, a midportion of the ladder  10  can displace forward-to-back, side-to-side and various combinations thereof. When a longitudinal axis  55  of an arm  50 ,  52  is oriented parallel to the orthogonal axis  23  (e.g. the arms  54 ,  56  are splayed a minimal amount), the stiffener  50 ,  52  provides a maximum resistance to the midportion of the ladder  10  traversing along the orthogonal axis  23  but a minimal resistance to the midportion of the ladder  10  traversing along the lateral axis  22 . When a longitudinal axis  55  of an arm  50 ,  52  is oriented parallel to the lateral axis  22  (e.g. the arms  54 ,  56  are splayed a maximum amount), the stiffener  50 ,  52  provides a maximum resistance to the midportion of the ladder  10  traversing along the lateral axis  22  but a minimal resistance to the midportion of the ladder  10  traversing along the orthogonal axis  23 . Orientations of the arms  54 ,  56  at angles to both the orthogonal axis  23  and the lateral axis  22  provide a desirable combination of reinforcement against movement along both the orthogonal axis  23  and the lateral axis  22 . 
     In some embodiments, the first cable  66  contacts the first arm  54  at a first contact location  81 . In some embodiments, the second cable  68  contacts the second arm  56  at a second contact location  83 . In some embodiments, a distance between the first contact location  81  and the second contact location  83  is greater than a distance between the first rail  14  and the second rail  16 . In some embodiments, a distance between the first contact location  81  and the second contact location  83  is greater than a distance between the second attachment location  72  and the fourth attachment location  76 . In some embodiments, a distance between the first contact location  81  and the second contact location  83  is greater than a distance between the first attachment location  70  and the third attachment location  74  (e.g. between a first cable lower attachment location and a second cable lower attachment location). 
     In some embodiments, a first arm  54  attaches to the first rail  14  at a location oriented to a first side of the longitudinal axis  21 , and the first arm  54  extends in a direction away from the longitudinal axis  21 . In some embodiments, the entire first arm  54  is located to a first side of the longitudinal axis  21 . In some embodiments, the entire first arm  54  is located to a first side of the first rail  14 . In some embodiments, a second arm  56  attaches to the second rail  16  at a location oriented to a second side of the longitudinal axis  21 , and the second arm  56  extends in a direction away from the longitudinal axis  21 . In some embodiments, the entire second arm  56  is located to a second side of the longitudinal axis  21 . In some embodiments, the entire second arm  56  is located to a second side of the second rail  16 . 
     In some embodiments, a stiffener  50 ,  52  is detachable from the ladder  10 . For example, in some embodiments, a cable  66  can be detached from the attachment locations  70 ,  72  and the arm  54  can be detached from the rail  14 . In some embodiments, the protrusions  48  are disengaged from the rungs  15 . Thus, the stiffener  50 ,  52  can be detached and stored when the ladder  10  is not in use. 
     Referring again to  FIG. 1 , in some embodiments, a ladder  10  comprises a first portion  20  and a second portion  30 , wherein the first portion  20  is moveable with respect to the second portion  30 . In some embodiments, a ladder  10  comprises an extension ladder, wherein the first portion  20  comprises a base section and the second portion  30  comprises a fly section. In some embodiments, the first portion  20  is arranged to move with respect to the second portion  30  in a linear manner, for example sliding parallel to a longitudinal axis  21  of the ladder. 
     In some embodiments, the first cable  66  is attached to the first portion  20  and to the second portion  30 . In some embodiments, the first cable  66  is attached at a first attachment location  70  to the first portion  20  and is attached at a second attachment location  72  to the second portion  30 . In some embodiments, the second cable  68  is attached to the first portion  20  and to the second portion  30 . In some embodiments, the second cable  68  is attached at a third attachment location  74  to the first portion  20  and is attached at a fourth attachment location  76  to the second portion  30 . 
       FIG. 11  shows an embodiment of a lock mechanism  78 . In some embodiments, a ladder  10  comprises a lock mechanism  78  arranged to apply forces between a first portion  20  and a second portion  30  of the ladder  10 . In some embodiments, a lock mechanism  78  is attached to the second portion  30  and comprises a contacting surface  79  arranged to contact the first portion  20 , or vice versa. In some embodiments, a lock mechanism  78  is attached to a rail  14  of the second portion  30  and the contacting surface  79  is arranged to contact a rung  15  of the first portion  20 . In some embodiments, the contacting surface  79  comprises a camming surface. 
     In some embodiments, a lock mechanism  78  comprises a bracket  84  and a cam bar  85 . In some embodiments, bracket  84  captures the cam bar  85 . In some embodiments, the bracket  84  is attached to a rail  14  and supports the cam bar  85 . In some embodiments, the bracket  84  defines a cavity and the cam bar  85  is positioned in the cavity. In some embodiments, the cavity defines a rotation axis  99  for the lock mechanism  78 . In some embodiments, the cam bar  85  comprises a handle  98  and the contacting surface  79 . In some embodiments, the handle  98  is oriented at an angle to the rotation axis  99 . In some embodiments, the contacting surface  79  is offset from the rotation axis  99 . 
     In some embodiments, the ladder  10  comprises a first lock mechanism  78  and further comprises a second lock mechanism  78   b . In some embodiments, a shape of a second lock mechanism  78   b  comprises a mirror image of a shape of a first lock mechanism  78 . 
     In use, a ladder  10  comprising a first portion  20  and a second portion  30  will often be stored in a collapsed orientation. A stiffener  50  can be attached to the ladder  10  with the ladder  10  in any suitable orientation, including the collapsed orientation. The ladder  10  can be extended by moving the second portion  30  with respect to the first portion  20 . Desirably, the cable  66  comprises an adjustment mechanism  90  if the ladder  10  is extended with the stiffener  50  attached to the ladder  10 , and the adjustment mechanism  90  is configured to be in an adjustable configuration such as being moveable along the length of the cable  66  during the extension process. The cable  66  can be tightened to the ladder  10  by applying tension to the cable  66  and configuring the adjustment mechanism  90  to be fixed along the length of the cable  66 . The lock mechanism  78  can be engaged, for example by rotating a portion of the lock mechanism  78  such as the cam bar  85 . In some embodiments, the lock mechanism  78  is attached to the second portion  30  of the ladder  10  and engaging the lock mechanism  78  causes the contacting surface  79  to contact the first portion  20  of the ladder. Desirably, the lock mechanism  78  transmits forces between the first portion  20  and second portion  30  of the ladder  10 . 
     Referring to  FIGS. 7 and 11 , in some embodiments, a ladder  10  comprises rung locks  37  as are generally known in the art, and further comprises a lock mechanism  78 . In some embodiments, a lock mechanism  78  is arranged to reduce the load applied to the rung locks  37 . 
       FIGS. 12 and 13  show another embodiment of a ladder  10  comprising a first stiffener  50  and a second stiffener  52 . 
     In some embodiments, a ladder  10  comprises a first portion  20  and a second portion  30 , wherein the first portion  20  is rotatable with respect to the second portion  30 . In some embodiments, the first portion  20  and second portion  30  are attached by a hinge  31  that defines a rotation axis. 
     In some embodiments, an arm  54 ,  56  of a stiffener  50 ,  52  is arranged to engage the first portion  20  and the second portion  30  of the ladder  10 . In some embodiments, an arm  54 ,  56  comprises a first leg  58  and a second leg  59 . In some embodiments, the first leg  58  is attached to the second portion  30  of the ladder  10 . In some embodiments, the first leg  58  comprises a protrusion  48  that extends through a rail  14 ,  16  of the second portion  30  and into a rung  15  of the second portion  30 . In some embodiments, the second leg  59  is attached to the first portion  20  of the ladder  10 . In some embodiments, the second leg  59  comprises a protrusion  48   b  that extends through a rail  14 ,  16  of the first portion  20  and into a rung  15  of the first portion  20 . 
       FIGS. 14 and 15  show another embodiment of a ladder  10  comprising a first stiffener  50  and a second stiffener  52 . In some embodiments, an arm  54 ,  56  of a stiffener  50 ,  52  comprises a clamp  102  arranged to engage a rail  14 ,  16  of the ladder  10 . In some embodiments, a clamp  102  provides a fixed connection between the rail  14 ,  16  and arm  54 ,  56  that is capable of transmitting moment forces. A clamp  102  can be secured or tightened using any suitable method. In some embodiments, a clamp  102  comprises a threaded fastener and a wing nut. 
       FIG. 16  shows an embodiment of a clamp  102  in greater detail. In some embodiments, a clamp  102  comprises a first jaw  104  and a second jaw  106 . In some embodiments, the jaws  104 ,  106  define a cavity  114  and a portion of a rail  14  is oriented in the cavity. 
     In some embodiments, a rail  14  comprises a channel section, C-shape or other suitable shape that comprises a web  18  and a flange  19 . In some embodiments, the web  18  and flange  19  comprise first and second portions of a rail  14  that are oriented at an angle to one another. 
     In some embodiments, the first jaw  104  comprises a first abutting surface  110  and a second abutting surface  112  oriented at an angle to one another. In some embodiments, the first abutting surface  110  is arranged to contact the web  18  of a rail  14  and the second abutting surface  112  is arranged to contact a flange  19  of the rail  14 . 
     In some embodiments, the second jaw  106  comprises a contoured shape that defines at least a portion of the cavity  114  and provides clearance for the flange  19 . In some embodiments, the second jaw  106  comprises a contacting portion  111  arranged to contact the web  18 . In some embodiments, the second jaw  106  contacts the first jaw  104 . In some embodiments, a clamp  102  comprises a hinge  107  or pivoting connection between the first jaw  104  and the second jaw  106 . 
     In various embodiments, an arm  54  can be arranged to extend away from the clamp  102  at any suitable angle to ladder  10 . In some embodiments, the arm  54  comprises a central axis  55  oriented parallel to the first abutting surface  110  of the first jaw  104 . In some embodiments, the arm  54  comprises a central axis  55  oriented at a non-zero angle to the first abutting surface  110  of the first jaw  104 . The non-zero angle can comprise any suitable angle. In some embodiments, the angle ranges from 1 degree to 89 degrees. In some embodiments, the angle ranges from 5 degrees to 45 degrees. In some embodiments, the angle is approximately 20 degrees. 
     In some embodiments, the central axis  55  is oriented at a non-zero angle to the second abutting surface  112  of the first jaw  104 . 
     In some embodiments, the arm  54  comprises a bracket  116  arranged to attach the clamp  102  to other portions of the arm  54 . In some embodiments, the bracket  116  comprises the first jaw  104 . In some embodiments, the bracket  116  is attached to a portion of the arm  54  that extends away from the ladder  10 . In some embodiments, the bracket  116  comprises a cavity  117  arranged to receive another portion of the arm  54 . In some embodiments, the cavity  117  comprises a central axis that is collinear with the central axis  55  of the arm  54 . 
       FIG. 17  shows an embodiment of a stiffener  50  arm  54  and cable  66  in a storage configuration. 
     In some embodiments, a stiffener  50  can be removed from the ladder  10  for storage. In some embodiments, the arm  54  is arranged to detach from the ladder  10 , for example comprising a clamp  102 . In some embodiments, an arm  54  comprises a storage bracket  97  for winding the cable  66 . In some embodiments, an arm  54  comprises two brackets  97 , which can face opposite directions, and the cable  66  can be wound around the brackets  97 . In some embodiments, a bracket  97  comprises an aperture  61  arranged to receive a connector  62  of the cable  66 . In some embodiments, the shape of an aperture  61  in a storage bracket  97  is similar to the shape of an aperture  61  in a bracket  60  attached to the ladder  10 . 
       FIG. 18  shows another embodiment of a ladder  10  comprising a first stiffener  50  and a second stiffener  52 . In some embodiments, an arm  54 ,  56  is attached to the ladder  10  and the arm  54 ,  56  is arranged to articulate with respect to the ladder  10 . In some embodiments, the arm  54 ,  56  is moveable between a storage position and at least one stiffening position. In some embodiments, an arm  54 ,  56  comprises an articulating portion  120  that allows a portion of the arm  54 ,  56  to move with respect to the ladder  10 . In some embodiments, the arm  54 ,  56  comprises an articulating bracket  122  that is attached to the ladder  10 . 
       FIG. 19  shows an embodiment of an arm  56  in greater detail and  FIG. 20  shows an embodiment of an articulating bracket  122  in greater detail. Desirably, an articulating portion  120  allows the arm  56  to move between a stiffening position, for example as shown in  FIGS. 18 and 19 , and a storage position, for example as shown in  FIG. 21 . 
     In some embodiments, when an arm  56  is in a stiffening position, a central axis  55  of the arm  56  is oriented at a non-zero angle to a longitudinal axis  21  and to a lateral axis  22  of the ladder  10 . In some embodiments, when the arm  56  is in a stiffening position, a central axis  55  of the arm  56  is further oriented at a non-zero angle to an orthogonal axis  23  of the ladder  10 . In some embodiments, when the arm  56  is in a storage position, a central axis  55  of the arm  56  is parallel to the longitudinal axis  21 . Thus, in some embodiments, an articulating portion  120  allows for movement with respect to at least two orthogonal axes. 
     In some embodiments, an articulating portion  120  provides for a swiveling motion. In some embodiments, an articulating portion  120  provides for a hinging motion. In some embodiments, an articulating portion  120  comprises both a swiveling connection and a hinging connection. 
     In some embodiments, an articulating bracket  122  is attached between the ladder  10  and an arm  56 . In some embodiments, an articulating bracket  122  is attached to a rail  16 . In some embodiments, an articulating bracket  122  comprises a connector  126  attached to the arm  56 , wherein the arm  56  is moveable with respect to the connector  126  about a first axis  130 . In some embodiments, the arm  56  is arranged to rotate about the first axis  130  with respect to the connector  126 . In some embodiments, the articulating bracket  122  further comprises a base plate  124 , and the connector  126  is attached to the base plate  124 . In some embodiments, the base plate  124  is attached to the rail  16 . In some embodiments, the connector  126  is moveable with respect to the base plate  124  about a second axis  132 . In some embodiments, the connector  126  is rotatable about the second axis  132  with respect to the base plate  124 . Thus, in some embodiments, the arm  56  and the connector  126  are rotatable with respect to the base plate  124  about the second axis  132 , and the arm  56  is further rotatable with respect to the connector  126  about the first axis  130 . In some embodiments, the first axis  130  is oriented nonparallel to the second axis  132 . In some embodiments, the first axis  130  is orthogonal with respect to the second axis  132 . In some embodiments, the second axis  132  is parallel to a lateral axis  22  of the ladder  10 . 
     In some embodiments, a positioner  134  is provided and arranged to help position the arm  56  in a stiffening position. In some embodiments, a positioner  134  is arranged to provide bracing forces to the arm  56  in the stiffening position. In some embodiments, the positioner  134  is arranged to position the arm  56  such that a central axis  55  of the arm  56  is oriented at an angle to an orthogonal axis  23  of the ladder  10 . In some embodiments, a positioner  134  is attached to a rail  16 . In some embodiments, an articulating bracket  122  comprises a positioner  134 . In some embodiments, a base plate  126  comprises a positioner  134 . 
     In some embodiments, a positioner  134  comprises a cantilever structure that is supported at one end and provides support to the arm  56  at another end. In some embodiments, the positioner  134  can function as a spring and provide controlled deformation in response to the loading conditions. 
     In some embodiments, a positioner  134  comprises a notch  136  arranged to abut and position the arm  56 . In some embodiments, the notch  136  comprises opposed inclined surfaces arranged to abut the arm  56 . In some embodiments, the notch  136  is centered in a plane defined by the lateral axis  22  and orthogonal axis  23  of the ladder  10 . 
     In some embodiments, a positioner  134  is arranged to position an arm  56  with its central axis  55  in a plane defined by the lateral axis  22  and orthogonal axis  23  of the ladder  10 . In some embodiments, a positioner  134  is arranged to position an arm  56  with its central axis  55  oriented substantially orthogonally to the longitudinal axis  21  of the ladder  10 . 
       FIG. 21  shows the ladder  10  of  FIGS. 18-20  in a storage configuration, with the first stiffener  50  and the second stiffener  52  in storage orientations. In some embodiments, the arms  54 ,  56  of each stiffener  50 ,  52  can be arranged in a storage position. In some embodiments, a central axis  55  of an arm  54 ,  56  is oriented parallel to a longitudinal axis  21  of the ladder when the arm  54 ,  56  is in the storage position. In some embodiments, a cable  66 ,  68  is wrapped onto the arm  54 ,  56  in the storage orientation. In some embodiments, the cable  66 ,  68  is wrapped onto storage brackets  97  provided on an arm  54 ,  56 . 
     In some embodiments, the ladder  10  comprises a capture bracket  138 . In some embodiments, the ladder  10  comprises a capture bracket  138  for each stiffener  50 ,  52 . In some embodiments, a capture bracket  138  is attached to a rail  14 ,  16 . In some embodiments, a capture bracket  138  is arranged to engage an arm  54 ,  56 . In some embodiments, a capture bracket  138  is arranged to retain the arm  54 ,  56  in a storage position. 
       FIGS. 22 and 23  show another embodiment of a lock mechanism  78 . In some embodiments, a lock mechanism  78  comprises a plate  89 . In some embodiments, the plate  89  comprises a flat body. In some embodiments, the lock mechanism  78  comprises a handle  98 . In some embodiments, the handle  98  comprises a portion of the plate  89  extending at an angle to the flat body. 
     Desirably, the lock mechanism  78  is attached to the ladder  10  and arranged to move with respect to the ladder  10 . In some embodiments, the lock mechanism  78  is arranged to rotate about a rotation axis  99 . In some embodiments, the rotation axis  99  is oriented parallel to a lateral axis  22  of the ladder. 
     In some embodiments, the plate  89  comprises an aperture  101 . In some embodiments, a retainer  100  is provided. In some embodiments, a retainer  100  is attached to a rail  14 ,  16 . In some embodiments, the retainer  100  engages the plate  89  and retains the plate  89  in a particular orientation, such as a stowed orientation. In some embodiments, the retainer  100  comprises a pin and the pin is arranged to extend into the aperture  101 . In some embodiments, the retainer  100  prevents the lock mechanism  78  from moving about the rotation axis  99 . 
     In some embodiments, the plate  89  is attached to a rail  14 ,  16  by a fastener  103 . In some embodiments, the fastener  103  defines the rotation axis  99 . In some embodiments, the fastener  103  provides a gap between a head of the fastener  103  and the rail  14 ,  16 , and in some embodiments, the gap is greater than a thickness of the plate  89 . This arrangement provides clearance for the plate  89  to be moved and disengaged from the retainer  100 . For example, the plate  89  can be rotated slightly about an axis oriented orthogonal to the rotation axis  99 , allowing the plate  89  to be lifted off the retainer  100 . In some embodiments, a biasing member  105  is provided and arranged to bias the plate  89  against the rail  14 ,  16 . In some embodiments, the biasing member  105  comprises a wave spring arranged to surround a shaft of the fastener  103 . In some embodiments, a wave spring biasing member  105  is provided between the head of the fastener  103  and the plate  89 . Thus, the biasing member  105  can bias the plate  89  to an orientation where the retainer  100  can capture the plate  89 , and the biasing can be overcome by lifting the plate  89  to remove the plate  89  from the retainer  100 . 
     Desirably, the lock mechanism  78  comprises a contacting surface  79 . In some embodiments, the contacting surface  79  comprises a camming surface. In some embodiments, an end of the plate  89  comprises a contacting surface  79 . In some embodiments, the plate  89  is attached to the second portion  30  of a rail  14 ,  16  and the contacting surface  79  is arranged to contact the first portion  20  of the ladder  10 . In some embodiments, the contacting surface  79  is arranged to contact a rung  15  of the first portion  20  of the ladder  10 . 
     In some embodiments, a ladder  10  comprises a first stiffener  50  and a second stiffener  52 , and further comprises a cross-brace attached between the first stiffener  50  and the second stiffener  52 . In some embodiments, a cross-brace is attached to a first arm  54  of the first stiffener  50  and a second arm  56  of the second stiffener  52 . 
     The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this field of art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to.” Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. 
     Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below. 
     This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.