Multi-purpose ladder and method for producing and using a multi-purpose ladder

Abstract

This application relates to a multipurpose ladder and methods for producing and using the same. The multipurpose ladder has a first inner section. The ladder has a first living hinge and a second living hinge. The ladder has a second inner section. The ladder has a first outer section. The ladder has a first locking bar. The ladder has a second outer section. The multipurpose ladder can have a plurality of braces disposed about an outer rail of the outer section. The braces provide support to each of the outer rails and strengthen them against bending forces, so the rails can be thinner and have a lighter weight. The ladder can have an ANSI load rating of 1A or an ANSI load rating of 1AA. The invention also provides a method of using a multipurpose ladder. The invention also provides a method for producing a multipurpose ladder.

Description

[0001] Information related to divisional application

[0002] This case is a divisional application. The parent application of this divisional application is the invention patent application filed on May 29, 2019, with application number 201910456038.2 and invention title "Multipurpose ladder and method for producing and using multipurpose ladder".

[0003] Cross-references to related applications

[0004] This case is a non-provisional case of U.S. Provisional Patent Application Serial No. 62 / 677,443, filed on May 29, 2018, which is incorporated herein by reference. Technical Field

[0005] This invention relates to a lightweight MT ladder with an ANSI load rating of 1A or 1AA. (As used herein, references to "invention" or "the invention" refer to exemplary embodiments and not necessarily to every embodiment covered by the appended claims). More specifically, this invention relates to a lightweight MT ladder with an ANSI load rating of 1A or 1AA, having a thinner track with supports positioned on the track at a higher bending force position when subjected to load to support the track at a higher bending force position. Background Technology

[0006] This section is intended to introduce the reader to various aspects of the art that may be associated with various aspects of the present invention. The following discussion is intended to provide information that will help in a better understanding of the invention. Therefore, it should be understood that the statements in the following discussion should be read with this in mind, and not as an endorsement of the prior art.

[0007] There is a need to produce multi-purpose ladders that are as sturdy and as lightweight as possible. The sturdiness requirement takes precedence over the lightness requirement because multi-purpose ladders must be safe to use and will not break down during use. In other words, a ladder can be made very light, but if it bends or collapses once someone climbs it, then the ladder is practically unusable for its intended purpose. What is needed is a lightweight multi-purpose ladder that can be used for its intended purpose and meets all the safety requirements of ANSI. Summary of the Invention

[0008] This invention relates to a multi-purpose ladder. The ladder includes a first inner section having a first right-side inner rail, a first left-side inner rail parallel and spaced apart from the first right-side inner rail, and a plurality of first inner rungs attached to the first left-side and first right-side inner rails. The ladder includes a first movable hinge attached to the first right-side inner rail via a first set of fasteners. The ladder includes a second movable hinge attached to the first left-side inner rail via a second set of fasteners. The ladder includes a second inner section having a second right-side inner rail, a second left-side inner rail parallel and spaced apart from the second right-side inner rail, and a plurality of second inner rungs attached to the second left-side and second right-side inner rails. The second right-side inner rail is attached to the first movable hinge and the second left-side inner rail is attached to the second movable hinge, thus the second inner section is rotatable relative to the first inner section about the first and second movable hinges by at least 80°. The ladder includes a first outer section having a first right outer rail, a first left outer rail parallel to and spaced apart from the first right outer rail, and a plurality of first outer steps attached to the first left and first right outer rails. The first right outer rail is positioned around a first right inner rail, wherein the first right inner rail slides vertically relative to the first right outer rail. The first right outer rail has a bend at least 7° outward relative to the first right inner rail, the first right inner rail defining a lower portion below the bend. The ladder includes a first locking lever attached to the first outer section, the first locking lever locking the first right inner rail in a locked position relative to the first right outer rail and allowing the first right inner rail to slide relative to the first right outer rail in an unlocked state. The ladder includes a second outer section having a second right outer rail, a second left outer rail parallel to and spaced apart from the second right outer rail, and a plurality of second outer steps attached to the second left and second right outer rails. The second right outer rail is positioned around a second right inner rail, wherein the second right inner rail slides vertically relative to the second right outer rail.The multi-purpose ladder has a weight-to-length ratio of less than 2.41 lbs / ft as a 14' IAA ANSI rated load multi-purpose ladder, or less than 2.27 lbs / ft as an 18' IAA ANSI rated load multi-purpose ladder, or less than 2.08 lbs / ft as a 22' IAA ANSI rated load multi-purpose ladder, or less than 2.34 lbs / ft as a 26' IAA ANSI rated load multi-purpose ladder, or less than 2.0 lbs / ft as a 14' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26 ...2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 18' IA ANSI rated load multi-purpose ladder, or less than ANSI rated load multipurpose ladders have a weight-to-length ratio of less than 2.00 lbs / ft.

[0009] This invention relates to a multi-purpose ladder. The ladder includes a first inner section having a first right-side inner rail, a first left-side inner rail parallel and spaced apart from the first right-side inner rail, and a plurality of first inner rungs attached to the first left-side and first right-side inner rails. The ladder includes a first movable hinge attached to the first right-side inner rail via a first set of fasteners. The ladder includes a second movable hinge attached to the first left-side inner rail via a second set of fasteners. The ladder includes a second inner section having a second right-side inner rail, a second left-side inner rail parallel and spaced apart from the second right-side inner rail, and a plurality of second inner rungs attached to the second left-side and second right-side inner rails. The second right-side inner rail is attached to the first movable hinge and the second left-side inner rail is attached to the second movable hinge, thus the second inner section is rotatable relative to the first inner section about the first and second movable hinges by at least 80°. The ladder includes a first outer section having a first right outer rail, a first left outer rail parallel to and spaced apart from the first right outer rail, and a plurality of first outer steps attached to the first left and first right outer rails. The first right outer rail is positioned around a first right inner rail, wherein the first right inner rail slides vertically relative to the first right outer rail. The first right outer rail has a bend at least 7° outward relative to the first right inner rail, the first right inner rail defining a lower portion below the bend. The ladder includes a first locking lever attached to the first outer section, the first locking lever locking the first right inner rail in a locked position relative to the first right outer rail and allowing the first right inner rail to slide relative to the first right outer rail in an unlocked state. The ladder includes a second outer section having a second right outer rail, a second left outer rail parallel to and spaced apart from the second right outer rail, and a plurality of second outer steps attached to the second left and second right outer rails, the second right outer rail being positioned around the second right inner rail, wherein the second right inner rail slides vertically relative to the second right outer rail. The ladder includes multiple supports positioned around the first right outer rail and the first left outer rail, as well as the second right outer rail and the second left outer rail. The supports provide support for each of the right and left outer rails and reinforce them against bending forces. The multi-purpose ladder has an ANSI load rating of at least 1A and can support a load of 300 lbs. without failure.

[0010] This invention relates to a method of using a multi-purpose ladder. The method includes the step of moving the ladder to a desired location. There is also the step of placing the ladder on the ground at the desired location, so that a user can climb the ladder. The ladder includes a first inner section having a first right inner rail, a first left inner rail parallel and spaced apart from the first right inner rail, and a plurality of first inner rungs attached to the first left and first right inner rails. The ladder includes a first movable hinge attached to the first right inner rail via a first set of fasteners. The ladder includes a second movable hinge attached to the first left inner rail via a second set of fasteners. The ladder includes a second inner section having a second right inner rail, a second left inner rail parallel and spaced apart from the second right inner rail, and a plurality of second inner rungs attached to the second left and second right inner rails. The second right inner rail is attached to the first movable hinge and the second left inner rail is attached to the second movable hinge, so that the second inner section can rotate at least 80° relative to the first inner section about the first and second movable hinges. The ladder includes a first outer section having a first right outer rail, a first left outer rail parallel to and spaced apart from the first right outer rail, and a plurality of first outer steps attached to the first left and first right outer rails. The first right outer rail is positioned around a first right inner rail, wherein the first right inner rail slides vertically relative to the first right outer rail. The first right outer rail has a bend at least 7° outward relative to the first right inner rail, the first right inner rail defining a lower portion below the bend. The ladder includes a first locking lever attached to the first outer section, the first locking lever locking the first right inner rail in a locked position relative to the first right outer rail and allowing the first right inner rail to slide relative to the first right outer rail in an unlocked state. The ladder includes a second outer section having a second right outer rail, a second left outer rail parallel to and spaced apart from the second right outer rail, and a plurality of second outer steps attached to the second left and second right outer rails. The second right outer rail is positioned around a second right inner rail, wherein the second right inner rail slides vertically relative to the second right outer rail.The multi-purpose ladder has a weight-to-length ratio of less than 2.41 lbs / ft as a 14' IAA ANSI rated load multi-purpose ladder, or less than 2.27 lbs / ft as an 18' IAA ANSI rated load multi-purpose ladder, or less than 2.08 lbs / ft as a 22' IAA ANSI rated load multi-purpose ladder, or less than 2.34 lbs / ft as a 26' IAA ANSI rated load multi-purpose ladder, or less than 2.0 lbs / ft as a 14' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26 ...2.00 lbs / ft as an IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs ANSI rated load multipurpose ladders have a weight-to-length ratio of less than 2.00 lbs / ft.

[0011] This invention relates to a method for manufacturing a multi-purpose ladder. The method includes assembling the ladder, which has a first inner section having a first right inner rail, a first left inner rail parallel and spaced apart from the first right inner rail, and a plurality of first inner steps attached to the first left and first right inner rails. A first movable hinge is attached to the first right inner rail via a first set of fasteners. A second movable hinge is attached to the first left inner rail via a second set of fasteners. The ladder includes a second inner section having a second right inner rail, a second left inner rail parallel and spaced apart from the second right inner rail, and a plurality of second inner steps attached to the second left and second right inner rails. The second right inner rail is attached to the first movable hinge and the second left inner rail is attached to the second movable hinge, thus allowing the second inner section to rotate at least 80° relative to the first inner section about the first and second movable hinges. The ladder includes a first outer section having a first right outer rail, a first left outer rail parallel to and spaced apart from the first right outer rail, and a plurality of first outer steps attached to the first left and first right outer rails. The first right outer rail is positioned around a first right inner rail, wherein the first right inner rail slides vertically relative to the first right outer rail. The first right outer rail has a bend at least 7° outward relative to the first right inner rail, the first right inner rail defining a lower portion below the bend. The ladder includes a first locking lever attached to the first outer section, the first locking lever locking the first right inner rail in a locked position relative to the first right outer rail and allowing the first right inner rail to slide relative to the first right outer rail in an unlocked state. The ladder includes a second outer section having a second right outer rail, a second left outer rail parallel to and spaced apart from the second right outer rail, and a plurality of second outer steps attached to the second left and second right outer rails. The second right outer rail is positioned around a second right inner rail, wherein the second right inner rail slides vertically relative to the second right outer rail.The multi-purpose ladder is described as follows: a 14' IAA ANSI rated load multi-purpose ladder with a weight-to-length ratio of less than 2.41 lbs / ft; an 18' IAA ANSI rated load multi-purpose ladder with a weight-to-length ratio of less than 2.27 lbs / ft; a 22' IAA ANSI rated load multi-purpose ladder with a weight-to-length ratio of less than 2.08 lbs / ft; a 26' IAA ANSI rated load multi-purpose ladder with a weight-to-length ratio of less than 2.34 lbs / ft; a 14' IA ANSI rated load multi-purpose ladder with a weight-to-length ratio of less than 2.0 lbs / ft; an 18' IA ANSI rated load multi-purpose ladder with a weight-to-length ratio of less than 2.00 lbs / ft; a 22' IA ANSI rated load multi-purpose ladder with a weight-to-length ratio of less than 1.90 lbs / ft; or a 26' IA... ANSI rated load multipurpose ladders have a weight-to-length ratio of less than 2.00 lbs / ft.

[0012] This invention relates to a method for manufacturing a multi-purpose ladder. The method includes assembling the ladder, which has a first inner section having a first right inner rail, a first left inner rail parallel and spaced apart from the first right inner rail, and a plurality of first inner steps attached to the first left and first right inner rails. A first movable hinge is attached to the first right inner rail via a first set of fasteners. A second movable hinge is attached to the first left inner rail via a second set of fasteners. The ladder includes a second inner section having a second right inner rail, a second left inner rail parallel and spaced apart from the second right inner rail, and a plurality of second inner steps attached to the second left and second right inner rails. The second right inner rail is attached to the first movable hinge and the second left inner rail is attached to the second movable hinge, thus allowing the second inner section to rotate at least 80° relative to the first inner section about the first and second movable hinges. The ladder includes a first outer section having a first right outer rail, a first left outer rail parallel to and spaced apart from the first right outer rail, and a plurality of first outer steps attached to the first left and first right outer rails. The first right outer rail is positioned around a first right inner rail, wherein the first right inner rail slides vertically relative to the first right outer rail. The first right outer rail has a bend at least 7° outward relative to the first right inner rail, the first right inner rail defining a lower portion below the bend. The ladder includes a first locking lever attached to the first outer section, the first locking lever locking the first right inner rail in a locked position relative to the first right outer rail and allowing the first right inner rail to slide relative to the first right outer rail in an unlocked state. The ladder includes a second outer section having a second right outer rail, a second left outer rail parallel to and spaced apart from the second right outer rail, and a plurality of second outer steps attached to the second left and second right outer rails. The second right outer rail is positioned around a second right inner rail, wherein the second right inner rail slides vertically relative to the second right outer rail. The multi-purpose ladder includes multiple supports positioned around the first right outer rail and the first left outer rail, as well as the second right outer rail and the second left outer rail. The supports provide support for each of the right and left outer rails and reinforce them against bending forces. The multi-purpose ladder has an ANSI load rating of at least 1A and can support a load of 300 lbs. without failure.

[0013] This invention relates to a multi-purpose ladder. The ladder includes a first inner section having a first right-side inner rail, a first left-side inner rail parallel and spaced apart from the first right-side inner rail, and a plurality of first inner rungs attached to the first left-side and first right-side inner rails. The ladder includes a first movable hinge attached to the first right-side inner rail via a first set of fasteners. The ladder includes a second movable hinge attached to the first left-side inner rail via a second set of fasteners. The ladder includes a second inner section having a second right-side inner rail, a second left-side inner rail parallel and spaced apart from the second right-side inner rail, and a plurality of second inner rungs attached to the second left-side and second right-side inner rails. The second right-side inner rail is attached to the first movable hinge and the second left-side inner rail is attached to the second movable hinge, thus the second inner section is rotatable relative to the first inner section about the first and second movable hinges by at least 80°. The ladder includes a first outer section having a first right outer rail, a first left outer rail parallel to and spaced apart from the first right outer rail, and a plurality of first outer steps attached to the first left and first right outer rails. The first right outer rail is positioned around a first right inner rail, wherein the first right inner rail slides vertically relative to the first right outer rail, and the first right outer rail has a bend at least 7° outward relative to the first right inner rail, defining a lower portion below the bend. The ladder includes a first locking lever attached to the first outer section, which, in a locked state, locks the first right inner rail in a suitable position relative to the first right outer rail and, in an unlocked state, allows the first right inner rail to slide relative to the first right outer rail. The ladder includes a second outer section having a second right outer rail, a second left outer rail parallel to and spaced apart from the second right outer rail, and a plurality of second outer steps attached to the second left and second right outer rails. The second right outer rail is positioned around the second right inner rail, wherein the second right inner rail slides up and down relative to the second right outer rail. The first and second right outer rails, as well as the first and second left outer rails, each have spokes less than 0.041 inches thick. The multipurpose ladder has an ANSI load rating of at least 1A and can support a load of at least 300 lbs. without failure, and passes a cantilever bending test, in which a load of 500 lbf is applied at right angles to the bottom of the first right outer rail at the spokes of the first right outer rail without failure.

[0014] This invention relates to a method of using a multi-purpose ladder. The method includes the step of moving the ladder to a desired location. There is also the step of placing the ladder on the ground at the desired location, so that a user can climb the ladder. The ladder includes a first inner section having a first right inner rail, a first left inner rail parallel and spaced apart from the first right inner rail, and a plurality of first inner rungs attached to the first left and first right inner rails. The ladder includes a first movable hinge attached to the first right inner rail via a first set of fasteners. The ladder includes a second movable hinge attached to the first left inner rail via a second set of fasteners. The ladder includes a second inner section having a second right inner rail, a second left inner rail parallel and spaced apart from the second right inner rail, and a plurality of second inner rungs attached to the second left and second right inner rails. The second right inner rail is attached to the first movable hinge and the second left inner rail is attached to the second movable hinge, so that the second inner section can rotate at least 80° relative to the first inner section about the first and second movable hinges. The ladder includes a first outer section having a first right outer rail, a first left outer rail parallel to and spaced apart from the first right outer rail, and a plurality of first outer steps attached to the first left and first right outer rails. The first right outer rail is positioned around a first right inner rail, wherein the first right inner rail slides vertically relative to the first right outer rail. The first right outer rail has a bend at least 7° outward relative to the first right inner rail, the first right inner rail defining a lower portion below the bend. The ladder includes a first locking lever attached to the first outer section, the first locking lever locking the first right inner rail in a locked position relative to the first right outer rail and allowing the first right inner rail to slide relative to the first right outer rail in an unlocked state. The ladder includes a second outer section having a second right outer rail, a second left outer rail parallel to and spaced apart from the second right outer rail, and a plurality of second outer steps attached to the second left and second right outer rails. The second right outer rail is positioned around a second right inner rail, wherein the second right inner rail slides vertically relative to the second right outer rail. The multi-purpose ladder includes multiple supports positioned around the first right outer rail and the first left outer rail, as well as the second right outer rail and the second left outer rail. The supports provide support for each of the right and left outer rails and reinforce them against bending forces. The multi-purpose ladder has an ANSI load rating of at least 1A and can support a load of 300 lbs. without failure. Attached Figure Description

[0015] The accompanying drawings illustrate preferred embodiments of the invention and preferred methods for practicing the invention, wherein:

[0016] Figure 1 This is a perspective view of the multipurpose ladder of the present invention, in which the visible support is shown.

[0017] Figure 2 This is a perspective view of a multi-purpose ladder in which the support legs are hidden.

[0018] Figure 3 The assembled inner support is shown on the first left outer track.

[0019] Figure 4 This is a side view of the outer track on the right side of the first track.

[0020] Figure 5 This is a cross-sectional view of the outer track on the right side of the first track.

[0021] Figure 6 This is a perspective view of the inner track on the right side of the first track.

[0022] Figure 7 This is a cross-sectional view of the inner track on the right side of the first track.

[0023] Figure 8 The cantilever bending test load is shown. The test load is 500 lbf for IA and 600 lbf for IAA.

[0024] Figure 9 This is a top view of the reinforcing plate.

[0025] Figure 10 This is a side view of the reinforcing plate.

[0026] Figure 11 This is a cross-sectional view of the reinforcing plate.

[0027] Figure 12 The reinforcing plates are shown relative to the inner track and the hidden outer track.

[0028] Figure 13 An exploded view of the multi-purpose ladder with reinforcement plates and outer rails is shown.

[0029] Figure 14 It is a cross-sectional view of a portion of the inner ladder that is snapped into the inner rail.

[0030] Figure 15 This is a cross-sectional view of the inner steps.

[0031] Figure 16 This is a perspective view of the inner steps.

[0032] Figure 17It is a perspective view of the intersection of the multi-purpose ladder and an enlarged view of the protrusions of the inner rungs that engage with the inner rails.

[0033] Figure 18 This is an enlarged view of the inner step's protrusions, which have been removed from the inner track and are engaged with it.

[0034] Figure 19 The movable hinges attached to the first and second inner rails are shown, with a hidden safety stop to eliminate pinch points.

[0035] Figure 20 This is a perspective view of the outer hinge plate assembly.

[0036] Figure 21 This is a front view of the outer hinge plate assembly.

[0037] Figure 22 This is an exploded perspective view of the outer hinge plate assembly.

[0038] Figure 23 This is a perspective view of the inner hinge plate assembly.

[0039] Figure 24 This is an exploded perspective view of the inner hinge plate assembly.

[0040] Figure 25 This is a front view of the inner hinge plate assembly.

[0041] Figure 26 This is a perspective view of the J-type lock plate.

[0042] Figure 27 The J-type locking plate attached to the outer track is shown.

[0043] Figure 28 This is a perspective view of the cross brace.

[0044] Figure 29 This is a perspective view of the support frame.

[0045] Figure 30 The assembled outer supports are shown on the outer rails of the ladder.

[0046] Figure 31 Showing a perspective front view of the outer support leg.

[0047] Figure 32 The perspective rear view of the outer support leg is shown.

[0048] Figure 33 Showing a top perspective view of the inner support leg.

[0049] Figure 34 Showing a bottom perspective view of the inner support leg.

[0050] Figure 35 An alternative embodiment of the inner support leg is shown. Detailed Implementation

[0051] Now, referring to the diagram where similar element symbols run through several views to represent similar or identical parts, and more specifically referring to its... Figure 1-3The image shows a multi-purpose (MT) ladder 10. The ladder 10 includes a first inner section 12 having a first right inner rail 14, a first left inner rail 16 parallel and spaced apart from the first right inner rail 14, and a plurality of first inner rungs 18 attached to the first left and first right inner rails. The ladder 10 includes a first movable hinge 20 attached to the first right inner rail 14 via a first set of fasteners 22. The ladder 10 includes a second movable hinge 24 attached to the first left inner rail 16 via a second set of fasteners 26. The ladder 10 includes a second inner section 28 having a second right inner rail 30, a second left inner rail 32 parallel and spaced apart from the second right inner rail 30, and a plurality of second inner rungs 34 attached to the second left and second right inner rails. The second right inner rail 30 is attached to the first movable hinge 20 and the second left inner rail 32 is attached to the second movable hinge 24, so the second inner section 28 can rotate at least 80° relative to the first inner section 12 about the first movable hinge 20 and the second movable hinge 24. The ladder 10 includes a first outer section 36 having a first right outer rail 38, a first left outer rail 40 parallel to and spaced apart from the first right outer rail 38, and a plurality of first outer steps 42 attached to the first left outer rail and the first right outer rail. The first right outer rail 38 is positioned around a first right inner rail 14, wherein the first right inner rail 14 slides up and down relative to the first right outer rail 38. The first right outer rail 38 has a bend 46 extending outward at least 7° relative to the first right inner rail 14, and the first right inner rail 14 defines a lower portion 44 below the bend 46. The ladder 10 includes a first locking lever 48 attached to a first outer section 36, which, in a locked state, locks the first right inner rail 14 in place relative to the first right outer rail 38, and in an unlocked state allows the first right inner rail 14 to slide relative to the first right outer rail 38. The ladder 10 includes a second outer section 50 having a second right outer rail 52, a second left outer rail 54 parallel to and spaced apart from the second right outer rail 52, and a plurality of second outer rungs 56 attached to the second left outer rail and the second right outer rail. The second right outer rail 52 is positioned around the second right inner rail 30, wherein the second right inner rail 30 slides vertically relative to the second right outer rail 52.The multi-purpose ladder 10 has a weight-to-length ratio of less than 2.41 lbs / ft as a 14' IAA ANSI rated load multi-purpose ladder, or less than 2.27 lbs / ft as an 18' IAA ANSI rated load multi-purpose ladder, or less than 2.08 lbs / ft as a 22' IAA ANSI rated load multi-purpose ladder, or less than 2.34 lbs / ft as a 26' IAA ANSI rated load multi-purpose ladder, or less than 2.0 lbs / ft as a 14' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 22' IA ANSI rated load multi-purpose ladder, or less than 26' IA... ANSI rated load multipurpose ladders have a weight-to-length ratio of less than 2.00 lbs / ft.

[0052] Alternatively, a multi-purpose ladder may have a weight-to-length ratio of less than or equal to 2.3 lbs / ft, 2.25 lbs / ft, or 2.17 lbs / ft as a 14' IAA ANSI rated load multi-purpose ladder, or less than or equal to 2.23 lbs / ft or 2.18 lbs / ft as an 18' IAA ANSI rated load multi-purpose ladder, or less than or equal to 2.06 lbs / ft as a 22' IAA ANSI rated load multi-purpose ladder, or less than or equal to 2.3 lbs / ft, 2.25 lbs / ft, or 2.19 lbs / ft as a 26' IAA ANSI rated load multi-purpose ladder, or less than or equal to 1.95 lbs / ft or 1.90 lbs / ft as a 14' IA ANSI rated load multi-purpose ladder, or less than or equal to 18' IAA ANSI rated load multi-purpose ladder. ANSI rated load multipurpose ladders have a weight-to-length ratio of less than or equal to 1.94 lbs / ft or 1.88 lbs / ft, or as a 22'IA ANSI rated load multipurpose ladder, a weight-to-length ratio of less than or equal to 1.85 lbs / ft or 1.81 lbs / ft, or as a 26'IA ANSI rated load multipurpose ladder, a weight-to-length ratio of less than or equal to 1.95 lbs / ft or 1.93 lbs / ft.

[0053] Ladders rated "A" are heavy-duty ladders capable of carrying heavy loads. IA ladders can support up to 300 pounds without failure. This makes them safe to carry a wide range of items, including heavier ones. Some IA ladders can support two people simultaneously. Type IA ladders are sufficient for most contractor, carpentry, and construction work. IAA ladders are the heaviest-load-bearing ladders available. They can support up to 375 pounds without failure. They are primarily used for jobs requiring users to transport extremely heavy items up and down the ladder. ANSI is an abbreviation for the American National Standards Institute. By definition, a ladder with an ANSI load rating of IA or IAA has all the necessary characteristics for safe use by the user and complies with all the requirements of the latest ANSI Code 2017, which is incorporated herein by reference. That is, for the purposes of this document, the weight of a ladder considering the corresponding length-to-weight ratio is the weight of a ladder having all the necessary characteristics for compliance with the requirements of the latest ANSI Code 2017. By adding brackets 58 at specific locations, the reinforced track can be lighter than the possible configuration without brackets 58. Furthermore, the MT ladder 10 achieves a reduced length-to-weight ratio compared to previously existing MT ladders, and this was achieved by discovering how to do so while still meeting requirements and complying with ANSI Code 2017; therefore, it not only reduces the weight of any MT ladder, but also reduces the weight in a way that allows the user to use the MT ladder 10 safely, because it meets requirements and complies with ANSI Code 2017.

[0054] This high-strength MT ladder 10 is designed to be the lightest MT ladder in the world and has at least an ANSI rating of IA. To achieve this, both the inner and outer rail walls are thinner than those of existing MT ladders. Furthermore, the inner steps, rear cross brace, hinge plate, hinge spacer, and outer legs have been optimized to reduce weight by eliminating material or reducing material thickness in areas where it is not needed.

[0055] The ladder 10 may include a plurality of supports 58 disposed around a first right outer rail 38 and a first left outer rail 40, as well as a second right outer rail 52 and a second left outer rail 54. The supports 58 provide support for each of the right and left outer rails and reinforce them against bending forces. The supports 58 are added to the outer rails of the MT ladder to locally reinforce the outer rails.

[0056] The ladder 10 may include a first bracket 60, one of the plurality of brackets 58, which is positioned on top of and attached adjacent to a first right outer rail 38 surrounding a first locking bar 48. The first bracket 60 has a shape conforming to the cross-sectional shape of the first right outer rail. The first bracket 60 is approximately 0.5 inches wide and approximately 0.1 inches thick on all sides.

[0057] The ladder 10 may include a second support 62, one of the plurality of supports 58, which is positioned around the first right outer rail 38 and above and attached adjacent to the second highest first outer step 64 and below the first locking bar 48. The second support 62 has a shape conforming to the cross-sectional shape of the first right outer rail 38.

[0058] Ladder 10 may include a third support 66, one of the plurality of supports 58, positioned around the first right outer rail 38 and below and attached adjacent to the second highest first outer rung 64. The third support 66 has a shape conforming to the cross-sectional shape of the first right outer rail 38. The second and third supports are approximately 1 inch wide and 0.1 inch thick on all sides.

[0059] The ladder 10 may include a fourth support 68, one of the plurality of supports 58, positioned around the bottom 70 of the first right outer track 38 and attached adjacent to it. The fourth support 68 has a shape conforming to the cross-sectional shape of the first right outer track 38. Figure 30-32 As shown, the fourth bracket 68 may be partially covered by the first right outer support leg 71, which fits onto the bottom 70 of the first right outer track 38. The first right outer support leg 71 and the first left outer support leg 73, which fits onto the bottom 70 of the first left outer track 40, are made of a single piece of plastic, such as polyurethane. Each first outer support leg, as well as the second right outer support leg and the second left outer support leg, which fit onto the bottom of the second right outer track 52 and the second left outer track 54 respectively, have a tread along their bottom surface to provide better grip and friction during use on the ground and to prevent track slippage; and have a sleeve into which each corresponding track fits, surrounding the bottom 70 of the corresponding track to protect the side of the corresponding track. A single rivet or bolt extends through the sleeve and the corresponding track to secure the corresponding support leg to the corresponding track. The cross-sectional shape of the sleeve conforms to the cross-sectional shape of the track. See also Figure 2 . refer to Figure 33 and 34The diagram shows an inner support leg 300 that fits into the bottom of an inner rail. The inner support leg 300 has vertical tapered ribs 302 on the exterior of the long wall 303 of its upper portion 304. The ribs 302 provide a tight fit with the inner rail. The upper portion 304 has the same rectangular cross-sectional shape as the inner rail, but is slightly smaller in width and length so that the upper portion 304 can fit into the inner rail at its bottom. In the short wall 305 of the upper portion 304 is a cutout 306 through which spear-shaped members of the bottom of the inner rail extend from the top flange 94 and the bottom flange 96. The spear-shaped members of the top flange 94 and the bottom flange 96 provide a reliable lock with the cutout 306 to prevent the inner support leg from detaching from the inner rail. The bottom portion 308 of the inner support leg 300 has a tread 310 to improve the adhesion friction of the inner rail on soft surfaces. The upper portion 304 and the bottom portion 308 can be a single piece of plastic or polyvinyl chloride, or they can be two separate pieces riveted together, such as... Figure 35 As shown in the image.

[0060] Ladder 10 may include a lower crossbar 72 attached to the first right outer rail 38 and the first left outer rail 40 and adjacent to the bottom 70 of the first right outer rail and the first left outer rail, such as Figure 3 and 28 As shown, a fifth bracket 74 of the plurality of brackets 58 is disposed inside the first right outer rail 38 and attached to the first right outer rail 38 at the position where the lower cross brace 72 is attached to the first right outer rail 38. The fifth bracket 74 has a shape conforming to the cross-sectional shape of the first right outer rail 38.

[0061] The ladder 10 may include a sixth support 76, one of the plurality of supports 58, which is located inside the first right outer rail 38 and attached to the first right outer rail 38 below the fifth support 74 and above the fourth support 68. The sixth support 76 has a shape conforming to the cross-sectional shape of the first right outer rail 38. Figure 29 This is a perspective view of the first through sixth brackets, each with dimensions identified. Each bracket has a snap 250 that grips the associated inner rail to prevent it from slipping off the outer rail during a horizontal bending test. The outer step is double-riveted to and between the first right and first left outer rails, and double-riveted to and between the second right and second left outer rails.

[0062] The first movable hinge 20 may include an inner hinge spacer and an outer hinge spacer with bolt holes 80, through which bolts 226 extend to attach the first movable hinge 20 to a first right-side outer track 38. The hinge spacers have local supports 84 around each bolt hole, wherein the supports 84 cause the spacers to be thicker than areas without supports 84. The supports 84 reinforce the inner and outer hinge spacers against cracking or breakage from forces applied to the rivets 226. The fourth, fifth, and sixth supports are approximately 1.5 inches wide and approximately 0.1 inches thick around their perimeter.

[0063] In addition, such as Figure 3 As shown, the first knee brace 73 extends through the sixth bracket 76 between the lower cross brace 72 and the first left outer rail 40, and is attached to both the lower cross brace 72 and the first left outer rail 40. Therefore, the sixth bracket 76 receives any force transmitted from the first knee brace 73 through the sixth bracket 76 to the first left outer rail 40. Similarly, the second knee brace 75 extends through the sixth bracket 76 between the lowest first outer step 42 and the first left outer rail 40, and is attached to both the lowest first outer step 42 and the first left outer rail 40. Therefore, the sixth bracket 76 receives any force transmitted from the second knee brace 75 through the sixth bracket 76 to the first left outer rail 40.

[0064] The first right outer track 38 may have spokes 86 and a first flange 88 extending perpendicularly from the spokes 86 and a second flange 90 extending perpendicularly from the spokes 86 and parallel to and spaced apart from the first flange 88. The first support 60 may also have spokes 86 and a first flange 88 extending perpendicularly from the spokes 86 and a second flange 90 extending perpendicularly from the spokes 86 and parallel to and spaced apart from the first flange 88 of the first support 60. The spokes 86 of the first support 60 contact and conform to the spokes 86 of the first right outer track 38, the first flange 88 of the first support 60 contacts and conforms to the first right outer track 38, and the second flange 90 of the second support 62 contacts and conforms to the second flange 90 of the first right outer track 38. Each of the additional supports 58, namely the second to the sixth supports, also has spokes 86, first flange 88 and second flange 90 conforming to the first right outer track 38 in the same manner as described with respect to the first support 60 conforming to the first right outer track 38.

[0065] Figure 20-25 The hinge plate shown has material removed to form a cutout 340 in the handle 224, thereby reducing weight. The handle 224 is engaged with a track by bolts 82, which secure the hinge plate to the track.

[0066] This invention relates to a method of using a multi-purpose ladder 10. The method includes the step of moving the ladder 10 to a desired location. There is also the step of placing the ladder 10 on the ground at the desired location so that a user can climb the ladder 10. The ladder 10 includes a first inner section 12 having a first right inner rail 14, a first left inner rail 16 parallel and spaced apart from the first right inner rail 14, and a plurality of first inner rungs 18 attached to the first left inner rail and the first right inner rail. The ladder 10 includes a first movable hinge 20 attached to the first right inner rail 14 via a first set of fasteners 22. The ladder 10 includes a second movable hinge 24 attached to the first left inner rail 16 via a second set of fasteners 26. The ladder 10 includes a second inner section 28 having a second right inner rail 30, a second left inner rail 32 parallel and spaced apart from the second right inner rail 30, and a plurality of second inner rungs 34 attached to the second left inner rail and the second right inner rail. The second right inner rail 30 is attached to the first movable hinge 20, and the second left inner rail 32 is attached to the second movable hinge 24, so that the second inner section 28 can rotate at least 80° relative to the first inner section 12 about the first movable hinge 20 and the second movable hinge 24. The ladder 10 includes a first outer section 36 having a first right outer rail 38, a first left outer rail 40 parallel to and spaced apart from the first right outer rail 38, and a plurality of first outer steps 42 attached to the first left outer rail and the first right outer rail. The first right outer rail 38 is positioned around a first right inner rail 14, wherein the first right inner rail 14 slides up and down relative to the first right outer rail 38. The first right outer rail 38 has a bend 46 extending outward at least 7° relative to the first right inner rail 14, and the first right inner rail 14 defines a lower portion 44 below the bend 46. The ladder 10 includes a first locking lever 48 attached to a first outer section 36, which, in a locked state, locks the first right inner rail 14 in place relative to the first right outer rail 38, and in an unlocked state allows the first right inner rail 14 to slide relative to the first right outer rail 38. The ladder 10 includes a second outer section 50 having a second right outer rail 52, a second left outer rail 54 parallel to and spaced apart from the second right outer rail 52, and a plurality of second outer rungs 56 attached to the second left outer rail and the second right outer rail. The second right outer rail 52 is positioned around the second right inner rail 30, wherein the second right inner rail 30 slides vertically relative to the second right outer rail 52.The multi-purpose ladder 10 has a weight-to-length ratio of less than 2.41 lbs / ft as a 14' IAA ANSI rated load multi-purpose ladder, or less than 2.27 lbs / ft as an 18' IAA ANSI rated load multi-purpose ladder, or less than 2.08 lbs / ft as a 22' IAA ANSI rated load multi-purpose ladder, or less than 2.34 lbs / ft as a 26' IAA ANSI rated load multi-purpose ladder, or less than 2.0 lbs / ft as a 14' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as a 18 ... ANSI rated load multipurpose ladders have a weight-to-length ratio of less than 2.00 lbs / ft. Alternatively, the aforementioned multipurpose ladders of different sizes may have the weight-to-length ratios described above.

[0067] This invention relates to a method of using a multi-purpose ladder 10. The method includes the step of moving the ladder 10 to a desired location. There is also the step of placing the ladder 10 on the ground at the desired location so that a user can climb the ladder 10. The ladder 10 includes a first inner section 12 having a first right inner rail 14, a first left inner rail 16 parallel and spaced apart from the first right inner rail 14, and a plurality of first inner rungs 18 attached to the first left inner rail and the first right inner rail. The ladder 10 includes a first movable hinge 20 attached to the first right inner rail 14 via a first set of fasteners 22. The ladder 10 includes a second movable hinge 24 attached to the first left inner rail 16 via a second set of fasteners 26. The ladder 10 includes a second inner section 28 having a second right inner rail 30, a second left inner rail 32 parallel and spaced apart from the second right inner rail 30, and a plurality of second inner rungs 34 attached to the second left inner rail and the second right inner rail. The second right inner rail 30 is attached to the first movable hinge 20, and the second left inner rail 32 is attached to the second movable hinge 24, so that the second inner section 28 can rotate at least 80° relative to the first inner section 12 about the first movable hinge 20 and the second movable hinge 24. The ladder 10 includes a first outer section 36 having a first right outer rail 38, a first left outer rail 40 parallel to and spaced apart from the first right outer rail 38, and a plurality of first outer steps 42 attached to the first left outer rail and the first right outer rail. The first right outer rail 38 is positioned around a first right inner rail 14, wherein the first right inner rail 14 slides up and down relative to the first right outer rail 38. The first right outer rail 38 has a bend 46 extending outward at least 7° relative to the first right inner rail 14, and the first right inner rail 14 defines a lower portion 44 below the bend 46. The ladder 10 includes a first locking lever 48 attached to a first outer section 36, which, in a locked state, locks the first right inner rail 14 in place relative to the first right outer rail 38, and in an unlocked state allows the first right inner rail 14 to slide relative to the first right outer rail 38. The ladder 10 includes a second outer section 50 having a second right outer rail 52, a second left outer rail 54 parallel to and spaced apart from the second right outer rail 52, and a plurality of second outer rungs 56 attached to the second left and second right outer rails. The second right outer rail 52 is positioned around the second right inner rail 30, wherein the second right inner rail 30 slides up and down relative to the second right outer rail 52. The multi-purpose ladder 10 includes a plurality of supports 58 positioned around the first right outer rail 38 and the first left outer rail 40, as well as the second right outer rail 52 and the second left outer rail 54. The supports 58 provide support for each of the right and left outer rails and reinforce them against bending forces. The multipurpose ladder 10 has an ANSI load rating of 1A and can support a load of 300 lbs without failure.

[0068] This invention relates to a method for manufacturing a multipurpose ladder 10. The method includes assembling a ladder 10 having a first inner section 12, the first inner section 12 having a first right inner rail 14, a first left inner rail 16 parallel and spaced apart from the first right inner rail 14, and a plurality of first inner steps 18 attached to the first left inner rail and the first right inner rail. A first movable hinge 20 is attached to the first right inner rail 14 by a first set of fasteners 22. A second movable hinge 24 is attached to the first left inner rail 16 by a second set of fasteners 26. The ladder 10 includes a second inner section 28 having a second right inner rail 30, a second left inner rail 32 parallel and spaced apart from the second right inner rail 30, and a plurality of second inner steps 34 attached to the second left inner rail and the second right inner rail. The second right inner rail 30 is attached to the first movable hinge 20, and the second left inner rail 32 is attached to the second movable hinge 24, so that the second inner section 28 can rotate at least 80° relative to the first inner section 12 about the first movable hinge 20 and the second movable hinge 24. The ladder 10 includes a first outer section 36 having a first right outer rail 38, a first left outer rail 40 parallel to and spaced apart from the first right outer rail 38, and a plurality of first outer steps 42 attached to the first left outer rail and the first right outer rail. The first right outer rail 38 is positioned around a first right inner rail 14, wherein the first right inner rail 14 slides up and down relative to the first right outer rail 38. The first right outer rail 38 has a bend 46 extending outward at least 7° relative to the first right inner rail 14, and the first right inner rail 14 defines a lower portion 44 below the bend 46. The ladder 10 includes a first locking lever 48 attached to a first outer section 36, which, in a locked state, locks the first right inner rail 14 in place relative to the first right outer rail 38, and in an unlocked state allows the first right inner rail 14 to slide relative to the first right outer rail 38. The ladder 10 includes a second outer section 50 having a second right outer rail 52, a second left outer rail 54 parallel to and spaced apart from the second right outer rail 52, and a plurality of second outer rungs 56 attached to the second left outer rail and the second right outer rail. The second right outer rail 52 is positioned around the second right inner rail 30, wherein the second right inner rail 30 slides vertically relative to the second right outer rail 52.The multi-purpose ladder 10 has a weight-to-length ratio of less than 2.41 lbs / ft as a 14' IAA ANSI rated load multi-purpose ladder, or less than 2.27 lbs / ft as an 18' IAA ANSI rated load multi-purpose ladder, or less than 2.08 lbs / ft as a 22' IAA ANSI rated load multi-purpose ladder, or less than 2.34 lbs / ft as a 26' IAA ANSI rated load multi-purpose ladder, or less than 2.0 lbs / ft as a 14' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as an 18' IA ANSI rated load multi-purpose ladder, or less than 1.90 lbs / ft as a 26' IA ANSI rated load multi-purpose ladder, or less than 2.00 lbs / ft as a 18 ... ANSI rated load multipurpose ladders have a weight-to-length ratio of less than 2.00 lbs / ft. Alternatively, the aforementioned multipurpose ladders of different sizes may have the weight-to-length ratios described above. The rails, rungs, and support 58 are made of aluminum, and specifically may be 6061-T6, 6061-T5, or 6005-T5 aluminum alloy.

[0069] This invention relates to a method for manufacturing a multipurpose ladder 10. The method includes assembling a ladder 10 having a first inner section 12, the first inner section 12 having a first right inner rail 14, a first left inner rail 16 parallel and spaced apart from the first right inner rail 14, and a plurality of first inner steps 18 attached to the first left inner rail and the first right inner rail. A first movable hinge 20 is attached to the first right inner rail 14 by a first set of fasteners 22. A second movable hinge 24 is attached to the first left inner rail 16 by a second set of fasteners 26. The ladder 10 includes a second inner section 28 having a second right inner rail 30, a second left inner rail 32 parallel and spaced apart from the second right inner rail 30, and a plurality of second inner steps 34 attached to the second left inner rail and the second right inner rail. The second right inner rail 30 is attached to the first movable hinge 20, and the second left inner rail 32 is attached to the second movable hinge 24, so that the second inner section 28 can rotate at least 80° relative to the first inner section 12 about the first movable hinge 20 and the second movable hinge 24. The ladder 10 includes a first outer section 36 having a first right outer rail 38, a first left outer rail 40 parallel to and spaced apart from the first right outer rail 38, and a plurality of first outer steps 42 attached to the first left outer rail and the first right outer rail. The first right outer rail 38 is positioned around a first right inner rail 14, wherein the first right inner rail 14 slides up and down relative to the first right outer rail 38. The first right outer rail 38 has a bend 46 extending outward at least 7° relative to the first right inner rail 14, and the first right inner rail 14 defines a lower portion 44 below the bend 46. The ladder 10 includes a first locking lever 48 attached to a first outer section 36, which, in a locked state, locks the first right inner rail 14 in place relative to the first right outer rail 38, and in an unlocked state allows the first right inner rail 14 to slide relative to the first right outer rail 38. The ladder 10 includes a second outer section 50 having a second right outer rail 52, a second left outer rail 54 parallel to and spaced apart from the second right outer rail 52, and a plurality of second outer rungs 56 attached to the second left and second right outer rails. The second right outer rail 52 is positioned around the second right inner rail 30, wherein the second right inner rail 30 slides up and down relative to the second right outer rail 52. The multi-purpose ladder 10 includes a plurality of supports 58 positioned around the first right outer rail 38 and the first left outer rail 40, as well as the second right outer rail 52 and the second left outer rail 54. The supports 58 provide support for each of the right and left outer rails and reinforce them against bending forces. The multipurpose ladder 10 has an ANSI load rating of 1A and can support a load of 300 lbs without failure.

[0070] Each outer rail has spokes 86 that are thinner than 0.041 inches, of which more than 80% of the spokes 86 have a circular surface, such as Figure 4 and 5 As shown in the diagram. Each outer track has a height of at least 3 inches, a cross-section of less than 0.3 in^2, and a flat surface of more than 0.45 in^4.

[0071] Preferably, each outer rail has 0.040-inch-thick spokes 86 for the 14IAA, 18IAA, and 22IAA MT ladders to achieve maximum weight reduction, where 14, 18, and 22 represent the height of the MT ladder 10 in feet. More than 80% of the spokes have a rounded surface, which allows for internal reinforcement and a more comfortable grip for the user. Preferably, each outer rail has a height of 3.27 inches, a cross-section of 0.279 in², and a flat surface of 0.473 in². The first flange 88 and the second flange 90 of the outer rail are 0.051 inches thick.

[0072] Each inner rail has a hollow box-shaped cross-section and spokes 92 that are thinner than 0.041 inches, a height of at least 2.8 inches, a cross-section of less than 0.41 in², and a flat surface of greater than 0.5 in², as shown. Figure 6 and 7 As shown in the diagram. Preferably, each inner rail has a right and left spoke, each 0.040 inches thick for maximum weight reduction, and a top flange 94 and a bottom flange 96, each 0.09 inches thick. Preferably, each inner rail has a height of 3.00 inches, a cross-section of 0.402 in², and a flat surface of 0.520 in². The right and left spokes of the inner rail are parallel and spaced apart and are perpendicularly attached to the top and bottom flanges of the inner rail to form a hollow box. Figure 19 As shown, the top of each inner track of the handle 224 that receives the hinge 20 is tilted downward and inward at an angle of about 27 degrees.

[0073] like Figure 9-13 As shown, a reinforcing plate 99 is disposed inside each outer track, extending downwards at least 4 inches from the upper section 100 of each outer track above the bend 102 in each outer track along the lower section 104 of each outer track. The reinforcing plate 99 conforms to the shape of the inner surface of the outer track. The reinforcing plate 99 has spokes 106 with the same curvature as the spokes 86 of the outer track, and a top reinforcing flange 108 and a bottom reinforcing flange 110 of the spokes 106 attached to the ends of the reinforcing plate 99. The top reinforcing flange and the bottom reinforcing flange are approximately 0.25 inches wide and approximately 0.22 inches long.

[0074] A reinforcing plate 99 is added to the interior of each of the outer rails on the 22IAA and 26IAA models to pass the ANSI single J-lock test. Material is moved to the ends of the reinforcing plate 99 to achieve the required strength, but the portion is allowed to have a low profile and fit into the interior of the outer rail without interfering with the operation of the ladder. The reinforcing plate 99 is seated on the interior of the outer rail and conforms to the shape of the inner surface of the outer rail. The reinforcing plate 99 has an upper section 100 extending approximately 1.5 inches above the bend 102 and a lower section 104 extending approximately 6.5 inches below the bend 102. The reinforcing plate 99 has spokes 106 approximately 0.040 inches thick and a curvature conforming to the spokes 86 of the outer rail and substantially the same as the curvature of the spokes 86 of the outer rail. The outer track has an upper section 112 and a lower section 114, and a bend 116 therebetween. The upper section 100 and lower section 104 of the reinforcing plate 99, as well as the bend 102, fit into the corresponding sections of the outer track. The reinforcing plate 99 is made of aluminum 6061-T6, 6005-T5, or an engineering equivalent.

[0075] like Figure 14-16 As shown, at least one inner step includes a hollow central portion 118; a top spoke 120 extending upward from the central portion 118; and a top flange 122 having a flat surface 124 on which a user can place their feet to stand. The top flange 122 is attached to the top spoke 120 at an acute angle preferably about 17 degrees to the top spoke 120, so that the flat surface 124 faces away from the center of the ladder, with the top spoke 120 located between the top flange 122 and the central portion 118. The top spoke 120 is less than 0.041 inches thick. At least one inner step includes a bottom spoke 126 extending downward from the central portion 118; and a bottom flange 128 having a flat surface 124 on which a user can place their feet to stand. The bottom flange 128 is attached to the bottom spokes 126 at an acute angle, so that the flat surface 124 of the bottom flange 128 faces away from the center of the ladder, with the bottom spokes 126 positioned between the bottom flange 128 and the center portion 118. The bottom spokes 126 are less than 0.041 inches thick. The center portion 118 extends beyond the top and bottom flanges of an inner step, thus extending through and snapping into the first right inner rail 14 and the first left inner rail 16 to secure an inner step in place.

[0076] like Figure 17 and 18As shown, the inner spokes 92 of the first right inner rail 14 and the first left inner rail 16 have a first hole 130, a second hole 132, a third hole 134, and a fourth hole 136. The top flange 122 of the first inner step 18 has a first protrusion 140 extending from a first end 148 and a first edge 150 of the top flange 122, which engages with a first hole 130 of the inner spoke 92 of the first right inner track 14; a second protrusion 142 extending from the first end 148 and a second edge 152 of the top flange 122, which engages with a second hole 132 of the inner spoke 92 of the first right inner track 14; a third protrusion 144 extending from the second end 154 and the first edge 150 of the top flange 122, which engages with a first hole 130 of the inner spoke 92 of the first left inner track 16; and a fourth protrusion 146 extending from the second end 154 and the second edge 152 of the top flange 122, which engages with a second hole 132 of the inner spoke 92 of the first left inner track 16. The bottom flange 128 of the first inner step 18 has a first protrusion 240 extending from a first end 248 and a first edge 250 of the bottom flange 128, which engages with a third hole 134 of the inner spoke 92 of the first right inner track 14; a second protrusion 142 extending from the first end 248 and a second edge 252 of the bottom flange 128, which engages with a fourth hole 136 of the inner spoke 92 of the first right inner track 14; a third protrusion 244 extending from the second end 254 and the first edge 250 of the bottom flange 128, which engages with a third hole 134 of the inner spoke 92 of the first left inner track 16; and a fourth protrusion 246 extending from the second end 254 and the second edge 252 of the bottom flange 128, which engages with a fourth hole 136 of the inner spoke 92 of the first left inner track 16.

[0077] The inner steps have been optimized to move material away from the center of gravity of the section (thinner spokes and clamps, thicker flanges) to facilitate a lighter design that will still pass the ANSI code for step strength. Additionally, four protrusions at the ends of the inner steps engage holes in the inner rails. Without this engagement, the step collapses during the step-to-side rail shear ANSI test.

[0078] like Figure 20-22As shown, the hinge includes an outer hinge plate assembly 200 having a left outer hinge plate 202; an outer hinge plate spacer 206 attached to the left outer hinge plate 202; and a right outer hinge plate 204 attached to the outer hinge plate spacer 206, wherein the outer hinge plate spacer 206 is disposed between the right outer hinge plate 204 and the left outer hinge plate 202; and a stop rivet 208 attached to the left outer hinge plate 202 and the right outer hinge plate 204 and extending at least 0.5 inches from the outer surfaces of the right outer hinge plate 204 and the left outer hinge plate 202 and disposed above the outer hinge plate spacer 206. The left outer hinge plate 202 and the right outer hinge plate 204 define a gap 218 therebetween. Figure 23-25 As shown, the hinge includes an inner hinge plate assembly 210 having a left inner hinge plate 212; a central inner hinge plate spacer 216 attached to the left inner hinge plate 212; and a right inner hinge plate 214 attached to the central inner hinge plate spacer 216, wherein the central inner hinge plate spacer 216 is disposed between the right inner hinge plate 214 and the left inner hinge plate 212. The left inner hinge plate 212, the right inner hinge plate 214, and the central inner hinge plate spacer 216 are disposed in a gap 218 of the outer hinge plate assembly 200 and each has an aligned groove 220. The movable hinge includes a pin 222 extending through the left outer hinge plate 202, the right outer hinge plate 204, the left inner hinge plate 212, the right inner hinge plate 214, and the central inner hinge plate spacer 216. The left outer hinge plate 202 and the right outer hinge plate 204 rotate about pin 222 relative to the left outer hinge plate 202, the right outer hinge plate 204, and the central inner hinge plate. When the left outer hinge plate 202 and the right outer hinge plate 204 rotate to the fully extended position relative to the left inner hinge plate 212, the right inner hinge plate 214, and the central inner hinge plate, each groove 220 abuts against the stop rivet 208 and is stopped from further rotation by the stop rivet 208. As indicated above, the safety stop created by the stop rivet 208 is precisely concealed within the hinge to eliminate pinch points, such as... Figure 19 As shown in the image.

[0079] like Figure 20-25As shown, the left inner hinge plate and spacer, the right inner hinge plate and spacer, the left outer hinge plate and spacer, and the right outer hinge plate and spacer each have a handle 224 that engages with the inner track. The handle 224 is inserted into and positioned within the hollow box of the inner track and is riveted in place by rivets 226 passing through the spokes 92 of the inner track and the handle 224. Extending from the handle 224 of the left inner hinge plate, the right inner hinge plate, the left outer hinge plate, and the right outer hinge plate is a neck 228, which transitions to a connecting portion 230, having a circular shape with a pinhole 232 at the center of the connecting portion 230 to receive a pin 222. At the center of the neck 228 of the left inner hinge plate, the right inner hinge plate, the left outer hinge plate, and the right outer hinge plate is a stop rivet hole 234 through which a stop rivet 208 passes, and adjacent to the bottom of the handle 224 is a cutout 340 in which material has been removed to reduce the total weight of the ladder. The left inner hinge plate 212 and the right inner hinge plate 214 also have a cutout 340 at the center of their necks 228. The safety stop of the movable hinge is positioned to place it inside the hinge plate assembly, thereby eliminating pinch points present in other MT ladders. The inner hinge plate assembly 210 has a left inner hinge plate spacer 236 and a right inner hinge plate spacer 238, wherein the left inner hinge plate spacer 236 is in direct contact with the left inner hinge plate 212, and the right inner hinge plate spacer 238 is in direct contact with the right inner hinge plate 214, wherein the left inner hinge plate 212, the right inner hinge plate 214, and the central inner hinge plate spacer 216 are positioned between the left inner hinge plate spacer 236 and the right inner hinge plate spacer 238. The spacers are made of plastic or polypropylene. The thickness of the outer hinge plate spacer 206 is between 0.6 inches and 0.7 inches. The thickness of the center inner hinge plate spacer 216 is between 0.2 inches and 0.3 inches. The thickness of the left and right inner hinge plate spacers is between 0.13 inches and 0.15 inches. The thickness of the left and right inner hinge plates is between 0.13 inches and 0.16 inches. The thickness of the left and right outer hinge plates is between 0.13 inches and 0.14 inches. The thickness of the outer hinge plate assembly 200 is between 0.7 inches and 0.9 inches. The thickness of the inner hinge plate assembly is between 0.7 inches and 0.9 inches.

[0080] Minimize the hinge plate thickness to reduce weight. Two design changes regarding the hinge are required to pass ANSI testing.

[0081] 1) The hinge plate alloy for 18', 22' and 26' ladders has been changed from 6061-T6 to the stronger alloy 7N01-T5.

[0082] 2) Add spacers to maintain the distance between the hinge plates. This improves the I value of the assembly in the horizontal direction.

[0083] A notch 340 is added to the hinge plate to remove material from locations where it is not necessary for strength, thus making the section lighter. The 14-foot and 18-foot MT ladders 10 use half-pipe rivets 226 and have a different hole pattern than the 22-foot and 26-foot MT ladders 10. The 22-foot and 26-foot MT ladders use solid rivets 226 due to the higher stress experienced during testing.

[0084] The J-lock reinforcing plate 342, made of a metal such as aluminum, has a J-lock plate hole 344 and is attached to the interior of the outer track by rivets 226. Therefore, the J-lock plate hole 344 aligns with the J-lock outer track hole 346, and the J-lock fits into and extends through the J-lock plate hole 344 and the J-lock outer track hole 346. Figure 1 , 26 As shown in Figure 27, a J-lock reinforcement plate 342 is added to the interior of the outer rail to provide additional strength around the J-lock in order to pass ANSI load tests, such as the step-to-side rail shear test. This design change is necessary for the 0.040" thick outer rail spokes. The thickness of the J-lock reinforcement plate 342 is between 0.3 inches and 0.4 inches, and preferably 0.36 inches. It is approximately 1.6 inches long by 1.6 inches wide and has a rectangular or square shape. Preferably, four rivets 226 attach the J-lock reinforcement plate 342 to the outer rail.

[0085] The tests required for MT ladders rated ANSI IAA to pass, in addition to supporting a load of 375 lbs., include the following:

[0086] Step-to-side rail shear test: 1200 lbf was applied to the side of each rung with a different profile for 60 seconds without any failure of the ladder components. Ladder in step mode.

[0087] Single-lock (J-lock) test: 1200 lbf is applied evenly to the rung immediately above the J-lock for 60 seconds without any failure of the ladder components. The ladder is in its fully extended position and leaning against a wall.

[0088] Horizontal bending limit position 1: Apply 460 lbf to the rung closest to the center of ladder 10 for 60 seconds without any failure of the ladder components. The ladder is in fully extended mode and horizontally supported at both ends.

[0089] Column and hardware load test: 1500 lbf was applied to the top rung of ladder 10 for 60 seconds without any failure of the ladder's components. The ladder was in fully extended mode and leaning against a wall.

[0090] Cantilever bending test: The test load is 500 lbf for IA and 600 lbf for IAA, and is applied at a right angle at spoke 86 to the bottom 70 of the first right outer rail 38 of the ladder 10, as shown. Figure 8 As shown, the first right outer rail 38 of the ladder 10 will not malfunction.

[0091] The MT ladder 10 passed all of these tests.

[0092] An example of a multi-purpose ladder 10 with a weight-to-length ratio is as follows:

[0093] The Werner model's extended orbital length and weight ratio

[0094] HSMT 14' IA 10.9 ft 20.6 lbs 1.89 lbs / ft

[0095] HSMT 18' IA 14.8 ft 27.6 lbs 1.87 lbs / ft

[0096] HSMT 22' IA 19.0 ft 34.1 lbs 1.80 lbs / ft

[0097] HSMT 26' IA 23.0 ft 44.1 lbs 1.92 lbs / ft

[0098] HSMT 14' IAA 10.9 ft 23.5 lbs 2.16 lbs / ft

[0099] HSMT 18' IAA 14.8 ft 32.1 lbs 2.17 lbs / ft

[0100] HSMT 22' IAA 19.0 ft 38.9 lbs 2.05 lbs / ft

[0101] HSMT 26' IAA 23.0 ft 50.2 lbs 2.18 lbs / ft

[0102] Although the invention has been described in detail in the foregoing embodiments for illustrative purposes, it should be understood that such details are for the purposes described only, and that those skilled in the art may make changes therein without departing from the spirit and scope of the invention, except as may be described in the appended claims.

Claims

1. A ladder comprising: The first section has a first right inner track, a first right outer track arranged around the first right inner track, and a first plurality of steps coupled to the first right inner track and the corresponding first left inner track; The second section has a second right inner track, a second right outer track arranged around the second right inner track, and a second plurality of steps coupled to the second right outer track and the corresponding second left outer track; A movable hinge rotatably secures the first section to the second section. The movable hinge includes a first right outer plate assembly coupled to a first right inner plate assembly. The first right outer plate assembly includes at least one right outer plate having a right outer handle portion with at least one notch and a right outer body portion. The first right inner plate assembly includes at least one right inner hinge plate having a right inner handle portion with at least one notch and a right inner body portion. The right outer body portion is coupled to the first right inner rail, and the right inner body portion is coupled to the second right inner rail. The first right outer panel assembly includes a central stop member spaced inward from the periphery of the right outer panel, and the right inner panel includes a corresponding stop groove. When the first section is rotated to the fully extended position, the stop groove engages with the stop member from the periphery inward.

2. The ladder according to claim 1, wherein the at least one right outer plate includes a first right outer plate spaced apart from a second right outer plate, the first right outer plate including a first right outer handle portion having a first cut, and the second right outer plate including a second right outer handle portion having a second cut aligned with the first cut.

3. The ladder according to claim 2, wherein the first right outer plate assembly includes a spacer disposed between the first right outer handle portion and the second right outer handle portion.

4. The ladder according to claim 1, wherein at least one right inner plate includes a first right inner plate spaced apart from a second right inner plate, the first right inner plate including a first right inner handle portion having a first cut, and the second right inner plate including a second right inner handle portion having a second cut aligned with the first cut.

5. The ladder according to claim 4, wherein the first right inner plate assembly includes a spacer disposed between the first right inner handle portion and the second right inner handle portion.

6. The ladder of claim 1, wherein at least one right inner plate includes a first right inner plate spaced apart from a second right inner plate, wherein the first right inner plate assembly further includes a first outer spacer and a second outer spacer, the first outer spacer being disposed between the first right inner plate and the second right inner rail, and the second outer spacer being disposed between the second right inner plate and the second right inner rail.

7. The ladder of claim 6, wherein the first outer spacer includes an opening for receiving a fastener and a support region disposed around the opening, such that the first outer spacer is thicker in the support region than outside the support region.

8. The ladder according to claim 1, wherein the right outer handle portion is disposed inside the cavity of the first right inner track, and wherein the right inner handle portion is disposed inside the cavity of the second right inner track.

9. The ladder according to claim 1, wherein at least one right outer plate includes a first right outer plate spaced apart from a second right outer plate to form a gap, and wherein at least one right inner plate includes a first right inner plate spaced apart from a second right inner plate, the first right inner plate and the second right inner plate being disposed within the gap.

10. The ladder according to claim 1, wherein the first right outer track includes a track bend that positions at least a portion of the first right outer track at an outward angle relative to the first right inner track. The ladder further includes a reinforcing plate disposed in contact with and aligned with the first right outer rail. The reinforcing plate has a plate bend disposed between an upper plate section and a lower plate section, wherein the rail bend is disposed between the upper rail section and the lower rail section, and wherein the plate bend contacts the rail bend, the upper plate section contacts the upper rail section, and the lower plate section contacts the lower rail section.

11. A ladder comprising: The first section has a first right inner track and a corresponding first left inner track. The first section also has a first right outer track and a corresponding first left outer track. The first right outer track is arranged around the first right inner track, and a first plurality of steps are coupled to the first right inner track and the corresponding first left inner track. The first right outer track has an inner portion and an outer portion arranged adjacent to the first right inner track. The second section has a second right inner track and a corresponding second left inner track. The second section also has a second right outer track and a corresponding second left outer track. The second right outer track is arranged around the second right inner track, and a second plurality of steps are coupled to the second right outer track and the corresponding second left outer track. A movable hinge that rotatably secures the first section to the second section, the movable hinge having at least one hinge plate with a notch; The first cross brace is coupled to the first right outer rail and the corresponding first left outer rail, and the first cross brace is disposed near the bottom end of the ladder; as well as A first inner support is disposed within the first right outer track and coupled to the inner portion of the first right outer track and the first cross brace, such that the first right outer track is located between the first inner support and the first cross brace, and the first inner support has a shape conforming to the cross-sectional shape of the first right outer track.

12. The ladder according to claim 11, further comprising: A reinforcing bracket is disposed around at least a portion of the first right outer track and adjacent to the bottom of the first right outer track, the reinforcing bracket having a shape conforming to the cross-sectional shape of the first right outer track.

13. The ladder of claim 12, wherein the reinforcing bracket is at least partially covered by a first right outer support leg portion fitted to the bottom of the first right outer track.

14. The ladder according to claim 11, further comprising: A second inner support is coupled to the inner portion of the first right outer track above the first inner support, the second inner support having a shape conforming to the cross-sectional shape of the first right outer track.

15. The ladder according to claim 14, further comprising: The second cross brace is coupled to the first right outer rail and the first left outer rail. The second cross brace is positioned adjacent to the lowest step of the first section. The second inner support is coupled to the first right outer rail at the position where the second cross brace is coupled to the first right outer rail.

16. The ladder of claim 15, wherein the first right outer rail includes a rail bend that positions at least a portion of the first right outer rail at an outward angle relative to the first right inner rail, the ladder further comprising: A reinforcing plate is positioned to contact and align with the first right outer track. The reinforcing plate has a plate bend disposed between an upper plate section and a lower plate section, wherein the track bend is disposed between the upper track section and the lower track section, and wherein the plate bend contacts the track bend, the upper plate section contacts the upper track section, and the lower plate section contacts the lower track section.

17. A ladder comprising: The first section has a first right inner track, a first right outer track arranged around the first right inner track, and a first plurality of steps coupled to the first right inner track; The second section has a second right inner track, a second right outer track arranged around the second right inner track, and a second plurality of steps coupled to the second right outer track; A movable hinge that rotatably secures the first section to the second section, the movable hinge having at least one hinge plate with a notch; as well as At least one of the first plurality of steps includes a top portion having a top flange, a bottom portion having a bottom flange, and a hollow central portion disposed between the top flange and the bottom flange, the top portion having top spokes extending between the hollow central portion and the top flange, and the bottom portion having bottom spokes extending between the hollow central portion and the bottom flange. The ends of the top flange and bottom flange of at least one step include protrusions that extend into the corresponding openings of the first right inner track.

18. The ladder of claim 17, wherein the at least one rung further comprises: Two first protrusions are provided on the edge of the top flange, and the two first protrusions engage with the corresponding two first openings on the first right inner track. And two second protrusions disposed on the edge of the bottom flange, the two second protrusions engaging with corresponding second openings in the first right inner track.

19. The ladder of claim 17, wherein the first right outer rail includes a rail bend that positions at least a portion of the first right outer rail at an outward angle relative to the first right inner rail, the ladder further comprising: A reinforcing plate is disposed within and in contact with the first right outer track and aligned with the first right outer track. The reinforcing plate has a plate bend disposed between an upper plate section and a lower plate section, wherein the track bend is disposed between the upper track section and the lower track section, and wherein the plate bend is in contact with the track bend, the upper plate section is in contact with the upper track section, and the lower plate section is in contact with the lower track section.

20. A multi-purpose ladder, comprising: The first inner section has a first right inner track, a first left inner track that is parallel to and spaced apart from the first right inner track, and a plurality of first inner steps attached to the first left inner track and the first right inner track. The first outer section has a first right outer track, a first left outer track parallel to and spaced apart from the first right outer track, and a plurality of first outer steps attached to the front flanges of the first left outer track and the first right outer track. The first right outer track is arranged around the first right inner track. The first right outer track has a bend that is at least 7° outward relative to the first right inner track. The first right inner track defines the lower portion of the first right outer track below the bend. A first locking lever is attached to the first outer section. In the locked state, the first locking lever locks the first right inner track in a proper position relative to the first right outer track, while in the unlocked state, it allows the first right inner track to slide relative to the first right outer track. A first bracket, which at least partially surrounds the first right outer rail, is positioned entirely above the first locking lever; The second bracket, which at least partially surrounds the first right outer rail, is located entirely below the first locking lever and above the second tallest of the plurality of first outer steps; and A third support, which at least partially surrounds the first right outer track, is spaced apart from the second support, and the entire third support is located below the second tallest step of the plurality of first outer steps. The second highest step of the plurality of first outer steps is connected to the front flange of the first right outer track between the second bracket and the third bracket. The first bracket, the second bracket, and the third bracket are configured to resist the longitudinal bending of the first right outer track.

21. The multipurpose ladder according to claim 20, wherein it has a weight-to-length ratio of less than 2.41 lbs / ft as a 14' IAA ANSI rated load multipurpose ladder, or less than 2.27 lbs / ft as an 18' IAA ANSI rated load multipurpose ladder, or less than 2.08 lbs / ft as a 22' IAA ANSI rated load multipurpose ladder, or less than 2.34 lbs / ft as a 26' IAA ANSI rated load multipurpose ladder, or less than 2.0 lbs / ft as a 14' IAA ANSI rated load multipurpose ladder, or less than 2.00 lbs / ft as an 18' IAA ANSI rated load multipurpose ladder, or less than 1.90 lbs / ft as a 22' IAA ANSI rated load multipurpose ladder, or less than 2.41 lbs / ft as a 14' IAA ANSI rated load multipurpose ladder, or less than 2.00 lbs / ft as an 18' IAA ANSI rated load multipurpose ladder, or less than 1.90 lbs / ft as a 26 ...2.00 lbs / ft as an 18' IAA ANSI rated load multipurpose ladder, or less than 1.90 lbs / ft as a 28' IAA ANSI rated load multipurpose ladder, or less than 2.00 lbs / ft as a 18' IAA ANSI rated load multipurpose ladder, or less than 1.9 ANSI rated load multipurpose ladders have a weight-to-length ratio of less than 2.00 lbs / ft.

22. The multipurpose ladder of claim 20, wherein the first support has a shape conforming to the cross-sectional shape of the first right outer rail; and the first support has a first support flange spaced apart from the second support flange by support spokes, and the first right outer rail has a first rail flange spaced apart from the second rail flange by rail spokes, wherein the first support flange contacts the first rail flange and the second support flange contacts the second rail flange.

23. The multipurpose ladder of claim 20, wherein the second support has a shape conforming to the cross-sectional shape of the first right outer track.

24. The multipurpose ladder of claim 20, wherein the third support has a shape conforming to the cross-sectional shape of the first right outer track.

25. The multipurpose ladder of claim 20, further comprising a fourth support disposed at least partially around and adjacent to the bottom of the first right outer rail, the fourth support having a shape conforming to the cross-sectional shape of the first right outer rail.

26. The multipurpose ladder of claim 25, further comprising a lower crossbar attached to the first right outer rail and the first left outer rail and adjacent to the bottom of the first right outer rail and the first left outer rail, and a fifth bracket disposed inside the first right outer rail and attached to the first right outer rail at the position where the lower crossbar is attached to the first right outer rail, the fifth bracket having a shape conforming to the cross-sectional shape of the first right outer rail.

27. The multipurpose ladder of claim 26, further comprising a sixth support disposed inside the first right outer rail and attached to the first right outer rail below the fifth support and above the fourth support, the sixth support having a shape conforming to the cross-sectional shape of the first right outer rail.

28. The multipurpose ladder of claim 20, wherein the multipurpose ladder further comprises a first movable hinge attached to the first right inner rail via a first set of fasteners, and wherein the first movable hinge comprises an outer hinge spacer having bolt holes through which bolts extend to attach the first movable hinge to the first right outer rail, wherein the bolt holes of the outer hinge spacer have bushings around each bolt hole, wherein the bushings cause the outer hinge spacer to be thicker than the areas in which no bushings are present, and the bushings reinforce the outer hinge spacer against cracking or breakage from forces applied to the bolts.

29. The multipurpose ladder of claim 20, wherein the first right outer track has spokes, a first flange extending perpendicularly from the spokes, and a second flange extending perpendicularly from the spokes and parallel to and spaced apart from the first flange, and wherein the first support has spokes, a first flange extending perpendicularly from the spokes, and a second flange extending perpendicularly from the spokes and parallel to and spaced apart from the first flange of the first support, the spokes of the first support contacting and conforming to the spokes of the first right outer track, the first flange of the first support contacting and conforming to the first support of the first right outer track, and the second flange of the second support contacting and conforming to the second flange of the first right outer track.

30. A ladder comprising: The first inner section has a first right inner track, a first left inner track that is parallel to and spaced apart from the first right inner track, and a plurality of first inner steps attached to the first left inner track and the first right inner track. The second inner section has a second right inner track, a second left inner track that is parallel to and spaced apart from the second right inner track, and a plurality of second inner steps attached to the second left inner track and the second right inner track; The first outer section has a first right outer track, a first left outer track that is parallel to and spaced apart from the first right outer track, and a plurality of first outer steps attached to the first left outer track and the first right outer track. The first right outer track has a bend that is at least 7° outward relative to the first right inner track, and the first right inner track defines a lower portion below the bend. The second outer section has a second right outer track, a second left outer track that is parallel to and spaced apart from the second right outer track, and a plurality of second outer steps attached to the second left outer track and the second right outer track. The second right outer track is arranged around the second right inner track, wherein the second right inner track slides up and down relative to the second right outer track. Multiple external supports are arranged around and fixed to the first right outer track, the first left outer track, the second right outer track, and the second left outer track. The multiple external supports provide support for each of the right outer track and the left outer track and reinforce them against bending forces. and An internal reinforcing plate is disposed between the first right outer track and the first right inner track. The internal reinforcing plate is fixed to the interior of the first right outer track at the bend along the first right outer track. The internal reinforcing plate conforms to the spokes of the first right outer track. The internal reinforcing plate further has a bend that aligns with the bend of the first right outer track.

31. The ladder of claim 30, wherein the first right outer rail and the second right outer rail, as well as the first left outer rail and the second left outer rail, each have spokes less than 0.041 inches thick; and wherein the plurality of outer supports include a first support having a first support flange spaced apart from a second support flange by support spokes, and the first right outer rail having a first rail flange spaced apart from a second rail flange by rail spokes, wherein the first support flange contacts the first rail flange and the second support flange contacts the second rail flange.

32. The ladder of claim 30, having an ANSI load rating of at least 1A and capable of supporting a load of at least 300 lbs without failure.

33. The ladder according to claim 30, wherein the first right inner rail and the first left inner rail have holes, and the first step of the plurality of first inner steps has a protrusion at each end of the first step, the protrusion engaging with the holes of the first right inner rail and the first left inner rail.

34. The ladder according to claim 33, wherein the first rung comprises: Hollow central section; A top spoke extending upward from the hollow center portion, and a top flange having a flat surface on which a user can place their feet, the top flange being attached to the top spoke at an acute angle such that the flat surface faces away from the center of the ladder, wherein the top spoke is located between the top flange and the hollow center portion, and the top spoke is less than 0.041 inches thick. The first step includes a bottom spoke extending downward from the hollow center portion, and a bottom flange having a flat surface on which a user can place their feet, the bottom flange being attached to the top spoke at an acute angle such that the flat surface faces away from the center of the ladder. The bottom spokes are attached to the bottom flange at an acute angle such that the flat surface of the bottom flange faces away from the center of the ladder, wherein the bottom spokes are located between the bottom flange and the hollow center portion, the bottom spokes are less than 0.041 inches thick, and the hollow center portion extends beyond the top flange and the bottom flange of the first step such that the hollow center portion extends through the first right inner rail and the first left inner rail and snaps into the first right inner rail and the first left inner rail to secure the first step in place.

35. The ladder of claim 30, further comprising a first movable hinge attached to the first right inner track via a first set of fasteners, wherein the first movable hinge comprises: An outer hinge plate assembly having a left outer hinge plate, an outer hinge plate spacer attached to the left outer hinge plate, and a right outer hinge plate attached to the outer hinge plate spacer, wherein the outer hinge plate spacer is disposed between the right outer hinge plate and the left outer hinge plate, and a rivet attached to the right outer hinge plate and the left outer hinge plate and extending at least 0.5 inches from the outer surfaces of the right outer hinge plate and the left outer hinge plate, and disposed between the outer hinge plate spacer. Above the component, the left outer hinge plate and the right outer hinge plate define a gap therebetween; the inner hinge plate assembly has a left inner hinge plate, a central inner hinge plate spacer attached to the left inner hinge plate, and a right inner hinge plate attached to the central inner hinge plate spacer, wherein the central inner hinge plate spacer is disposed between the right inner hinge plate and the left inner hinge plate, the left inner hinge plate, the right inner hinge plate, and the central inner hinge plate spacer are disposed in the gap of the outer hinge plate assembly and each has an aligned groove; A pin extends through the left outer hinge plate and the right outer hinge plate, as well as the left inner hinge plate, the right inner hinge plate, and the center inner hinge plate spacer. The left outer hinge plate and the right outer hinge plate rotate about the pin relative to the left outer hinge plate, the right outer hinge plate, and the center inner hinge plate. When the left outer hinge plate and the right outer hinge plate rotate to their fully extended positions relative to the left inner hinge plate, the right inner hinge plate, and the center inner hinge plate, each groove abuts the rivet and is stopped from further rotation by the rivet.

36. The ladder of claim 30, further comprising a first locking lever attached to the first outer section, the first locking lever, in a locked state, locking the first right inner rail in a suitable position relative to the first right outer rail, and in an unlocked state allowing the first right inner rail to slide relative to the first right outer rail. The first locking lever includes a J-lock and a J-lock reinforcing plate made of metal with a J-lock plate hole. The J-lock reinforcing plate is attached to the inside of the first right outer track by rivets so that the J-lock plate hole is aligned with the J-lock outer track hole, thereby allowing the J-lock to engage in the J-lock plate hole and the J-lock outer track hole and extend through the J-lock plate hole and the J-lock outer track hole.

37. The ladder of claim 36, having an ANSI load rating of at least 1AA and supporting a load of at least 375 lbs. without failure and passing a step-to-side rail shear test, wherein 1200 lbf is applied to the side of each rung with a different profile for 60 seconds and the ladder components do not fail; a single J-lock test, wherein 1200 lbf is uniformly applied to the rung immediately above the J-lock for 60 seconds and the ladder components do not fail, and the ladder is in a fully extended mode and leaning against a wall; a horizontal bending limit 1 position test, wherein 460 lbf is applied to the rung closest to the center of the ladder for 60 seconds and the ladder components do not fail, and the ladder is in a fully extended mode and horizontally supported at both ends; a column and hardware load test, wherein 1500 The test involves applying 500 lbf to the top rung of the ladder for 60 seconds without any failure of the ladder components, and the ladder being in a fully extended mode and leaning against a wall; and a cantilever bending test, in which 500 lbf is applied at right angles to the bottom of the first right outer rail at the spokes, and the first right outer rail does not fail.

38. A multi-purpose ladder, comprising: The first inner section has a first right inner track, a first left inner track that is parallel to and spaced apart from the first right inner track, and a plurality of first inner steps attached to the first left inner track and the first right inner track. The first outer section has a first right outer track, a first left outer track parallel to and spaced apart from the first right outer track, and a plurality of first outer steps attached to the first left outer track and the first right outer track. The first right outer track is arranged around the first right inner track. The first right outer track has a bend that is at least 7° outward relative to the first right inner track. The first right inner track defines a lower portion below the bend. A plurality of supports are disposed around and fixed to the first right outer track and the first left outer track, the plurality of supports providing support for each of the right outer track and the left outer track and reinforcing them against bending forces, wherein each of the plurality of supports fixed to the first right outer track includes at least one latch that grips the first right inner track to restrict movement of the first right inner track relative to the first right outer track, and wherein each of the plurality of supports fixed to the first left outer track includes at least one latch that grips the first left inner track to restrict movement of the first left inner track relative to the first left outer track; and A reinforcing plate is disposed within and in contact with the first right outer track and aligned with it. The reinforcing plate and the first right outer track each have an upper section and a curved portion connected to the upper section, and a lower section connected to the curved portion, wherein the curved portion is between the upper section and the lower section. The curved portion of the reinforcing plate contacts the curved portion of the first right outer track, the upper section of the reinforcing plate contacts the upper section of the first right outer track, and the lower section of the reinforcing plate contacts the lower section of the first right outer track.

39. The multipurpose ladder of claim 38, having an ANSI load rating of at least 1A and capable of supporting a load of at least 300 lbs without failure.

40. The multipurpose ladder of claim 38, further comprising: The first movable hinge is attached to the first right inner rail via a first set of fasteners; A second movable hinge, which is attached to the first left inner rail via a second set of fasteners; and The second inner section has a second right inner rail, a second left inner rail parallel to and spaced apart from the second right inner rail, and a plurality of second inner steps attached to the second left inner rail and the second right inner rail. The second right inner rail is attached to the first movable hinge and the second left inner rail is attached to the second movable hinge, such that the second inner section can rotate at least 80° relative to the first inner section about the first movable hinge and the second movable hinge. The first right outer rail and the first left outer rail each have spokes less than 0.041 inches thick.

41. The multipurpose ladder according to claim 38, further comprising: A first locking lever, attached to the first outer section, locks the first right inner track in a locked state at an appropriate position relative to the first right outer track, and in an unlocked state allows the first right inner track to slide relative to the first right outer track; and A first bracket, which at least partially surrounds the first right outer rail, is positioned entirely above the first locking lever.

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