Patent Application
20190368271
The present invention is related to a lighter weight MT ladder that has an ANSI duty rating of 1A or a lighter weight MT ladder that has an ANSI duty rating of 1AA. (As used herein, references to the “present invention” or “invention” relate to exemplary embodiments and not necessarily to every embodiment encompassed by the appended claims.) More specifically, the present invention is related to a lighter weight MT ladder that has an ANSI duty rating of 1A or a lighter weight MT ladder that has an ANSI duty rating of 1AA that has thinner rails with brackets positioned at higher bending force locations on the rails when subjected to loads to buttress the rails at the higher bending force locations.
This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
It is desirable to produce a multipurpose ladder that is as strong as possible and as light as possible. The strength requirement of the multipurpose ladder is controlling with respect to the light weight requirement because the multipurpose ladder must be safe to use and not fail during use. In other words, the ladder could be made to be very light weight, but as soon as someone climbs on it, the ladder bends over or collapses and effectively there is no ladder that can be used for its intended purpose. What is needed is a lighter weight multipurpose ladder which can be used for its intended purpose and meets all the safety requirements required by ANSI.
The present invention pertains to a multipurpose ladder. The ladder comprises a first inner section having a first inner right rail, a first inner left rail in parallel and spaced relation with the first inner right rail and a plurality of first inner rungs attached to the first inner left and right rail. The ladder comprises a first articulated hinge attached to the first inner right rail with a first set of fasteners. The ladder comprises a second articulated hinge attached to the first inner left rail with a second set of fasteners. The ladder comprises a second inner section having a second inner right rail, and a second inner left rail in parallel and spaced relation with the second inner right rail and a plurality of second inner rungs attached to the second inner left and right rails. The second inner right rail attached to the first articulated hinge and the second inner left rail attached to the second articulated hinge so the second inner section can rotate about the first and second articulated hinges at least 80° relative to the first inner section. The ladder comprises a first outer section having a first outer right rail, and a first outer left rail in parallel and spaced relation with the first outer right rail and a plurality of first outer rungs attached to the first outer left and right rails. The first outer right rail disposed about the first inner right rail with the first inner right rail sliding up and down relative to the first outer right rail. The first outer right rail having a bend of at least 7° outward relative to the first inner right rail which defines a lower portion below the bend. The ladder comprises a first locking bar attached to the first outer section which locks the first inner right rail in place relative to the first outer right rail in a locked state and allows the first inner right rail to slide relative to the first outer right rail in the unlocked state. The ladder comprises a second outer section having a second outer right rail, and a second outer left rail in parallel and spaced relation with the second outer right rail and a plurality of second outer rungs attached to the second outer left and right rails. The second outer right rail disposed about the second inner right rail with the second inner right rail sliding up and down relative to the second outer right rail. The multipurpose ladder having a weight to length ratio of less than 2.41 lbs/ft as a 14′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.27 lbs/ft as a 18′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.08 lbs/ft as a 22′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.34 lbs/ft as a 26′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.0 lbs/ft as a 14′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 18′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 1.90 lbs/ft as a 22′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 26′ IA ANSI duty rated multipurpose ladder.
The present invention pertains to a multipurpose ladder. The ladder comprises a first inner section having a first inner right rail, a first inner left rail in parallel and spaced relation with the first inner right rail and a plurality of first inner rungs attached to the first inner left and right rail. The ladder comprises a first articulated hinge attached to the first inner right rail with a first set of fasteners. The ladder comprises a second articulated hinge attached to the first inner left rail with a second set of fasteners. The ladder comprises a second inner section having a second inner right rail, and a second inner left rail in parallel and spaced relation with the second inner right rail and a plurality of second inner rungs attached to the second inner left and right rails. The second inner right rail attached to the first articulated hinge and the second inner left rail attached to the second articulated hinge so the second inner section can rotate about the first and second articulated hinges at least 80° relative to the first inner section. The ladder comprises a first outer section having a first outer right rail, and a first outer left rail in parallel and spaced relation with the first outer right rail and a plurality of first outer rungs attached to the first outer left and right rails. The first outer right rail disposed about the first inner right rail with the first inner right rail sliding up and down relative to the first outer right rail. The first outer right rail having a bend of at least 7° outward relative to the first inner right rail which defines a lower portion below the bend. The ladder comprises a first locking bar attached to the first outer section which locks the first inner right rail in place relative to the first outer right rail in a locked state and allows the first inner right rail to slide relative to the first outer right rail in the unlocked state. The ladder comprises a second outer section having a second outer right rail, and a second outer left rail in parallel and spaced relation with the second outer right rail and a plurality of second outer rungs attached to the second outer left and right rails, the second outer right rail disposed about the second inner right rail with the second inner right rail sliding up and down relative to the second outer right rail. The ladder comprises a plurality of brackets disposed about the first outer right rail, and the first outer left rail, and the second outer right rail, and the second outer left rail. The brackets providing support to each of the outer right rails and outer left rails and strengthens them against bending forces. The multipurpose ladder having an ANSI duty rating of 1A and supports 300 lbs. of load without failing.
The present invention pertains to a method for using a multipurpose ladder. The method comprises the steps of moving the ladder to a desired location. There is the step of placing the ladder on ground at the desired location so a user can climb the ladder. The ladder comprises a first inner section having a first inner right rail, a first inner left rail in parallel and spaced relation with the first inner right rail and a plurality of first inner rungs attached to the first inner left and right rail. The ladder comprises a first articulated hinge attached to the first inner right rail with a first set of fasteners. The ladder comprises a second articulated hinge attached to the first inner left rail with a second set of fasteners. The ladder comprises a second inner section having a second inner right rail, and a second inner left rail in parallel and spaced relation with the second inner right rail and a plurality of second inner rungs attached to the second inner left and right rails. The second inner right rail attached to the first articulated hinge and the second inner left rail attached to the second articulated hinge so the second inner section can rotate about the first and second articulated hinges at least 80° relative to the first inner section. The ladder comprises a first outer section having a first outer right rail, and a first outer left rail in parallel and spaced relation with the first outer right rail and a plurality of first outer rungs attached to the first outer left and right rails. The first outer right rail disposed about the first inner right rail with the first inner right rail sliding up and down relative to the first outer right rail. The first outer right rail having a bend of at least 7° outward relative to the first inner right rail which defines a lower portion below the bend. The ladder comprises a first locking bar attached to the first outer section which locks the first inner right rail in place relative to the first outer right rail in a locked state and allows the first inner right rail to slide relative to the first outer right rail in the unlocked state. The ladder comprises a second outer section having a second outer right rail, and a second outer left rail in parallel and spaced relation with the second outer right rail and a plurality of second outer rungs attached to the second outer left and right rails. The second outer right rail disposed about the second inner right rail with the second inner right rail sliding up and down relative to the second outer right rail. The multipurpose ladder having a weight to length ratio of less than 2.41 lbs/ft as a 14′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.27 lbs/ft as a 18′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.08 lbs/ft as a 22′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.34 lbs/ft as a 26′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.0 lbs/ft as a 14′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 18′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 1.90 lbs/ft as a 22′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 26′ IA ANSI duty rated multipurpose ladder.
The present invention pertains to a method for producing a multipurpose ladder. The method comprises the steps of assembling the ladder with a first inner section having a first inner right rail, a first inner left rail in parallel and spaced relation with the first inner right rail and a plurality of first inner rungs attached to the first inner left and right rail. Attaching a first articulated hinge to the first inner right rail with a first set of fasteners. Attaching a second articulated hinge to the first inner left rail with a second set of fasteners. The ladder comprises a second inner section having a second inner right rail, and a second inner left rail in parallel and spaced relation with the second inner right rail and a plurality of second inner rungs attached to the second inner left and right rails. The second inner right rail attached to the first articulated hinge and the second inner left rail attached to the second articulated hinge so the second inner section can rotate about the first and second articulated hinges at least 80° relative to the first inner section. The ladder comprises a first outer section having a first outer right rail, and a first outer left rail in parallel and spaced relation with the first outer right rail and a plurality of first outer rungs attached to the first outer left and right rails. The first outer right rail disposed about the first inner right rail with the first inner right rail sliding up and down relative to the first outer right rail. The first outer right rail having a bend of at least 7° outward relative to the first inner right rail which defines a lower portion below the bend. The ladder comprises a first locking bar attached to the first outer section which locks the first inner right rail in place relative to the first outer right rail in a locked state and allows the first inner right rail to slide relative to the first outer right rail in the unlocked state. The ladder comprises a second outer section having a second outer right rail, and a second outer left rail in parallel and spaced relation with the second outer right rail and a plurality of second outer rungs attached to the second outer left and right rails. The second outer right rail disposed about the second inner right rail with the second inner right rail sliding up and down relative to the second outer right rail. The multipurpose ladder having a weight to length ratio of less than 2.41 lbs/ft as a 14′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.27 lbs/ft as a 18′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.08 lbs/ft as a 22′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.34 lbs/ft as a 26′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.0 lbs/ft as a 14′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 18′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 1.90 lbs/ft as a 22′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 26′ IA ANSI duty rated multipurpose ladder.
The present invention pertains to a method for producing a multipurpose ladder. The method comprises the steps of assembling the ladder with a first inner section having a first inner right rail, a first inner left rail in parallel and spaced relation with the first inner right rail and a plurality of first inner rungs attached to the first inner left and right rail. Attaching a first articulated hinge to the first inner right rail with a first set of fasteners. Attaching a second articulated hinge to the first inner left rail with a second set of fasteners. The ladder comprises a second inner section having a second inner right rail, and a second inner left rail in parallel and spaced relation with the second inner right rail and a plurality of second inner rungs attached to the second inner left and right rails. The second inner right rail attached to the first articulated hinge and the second inner left rail attached to the second articulated hinge so the second inner section can rotate about the first and second articulated hinges at least 80° relative to the first inner section. The ladder comprises a first outer section having a first outer right rail, and a first outer left rail in parallel and spaced relation with the first outer right rail and a plurality of first outer rungs attached to the first outer left and right rails. The first outer right rail disposed about the first inner right rail with the first inner right rail sliding up and down relative to the first outer right rail. The first outer right rail having a bend of at least 70 outward relative to the first inner right rail which defines a lower portion below the bend. The ladder comprises a first locking bar attached to the first outer section which locks the first inner right rail in place relative to the first outer right rail in a locked state and allows the first inner right rail to slide relative to the first outer right rail in the unlocked state. The ladder comprises a second outer section having a second outer right rail, and a second outer left rail in parallel and spaced relation with the second outer right rail and a plurality of second outer rungs attached to the second outer left and right rails. The second outer right rail disposed about the second inner right rail with the second inner right rail sliding up and down relative to the second outer right rail. The multipurpose ladder comprises a plurality of brackets disposed about the first outer right rail, and the first outer left rail, and the second outer right rail, and the second outer left rail. The brackets providing support to each of the outer right rails and outer left rails and strengthens them against bending forces. The multipurpose ladder having an ANSI duty rating of 1A and supports 300 lbs. of load without failing.
The present invention pertains to a multipurpose ladder. The ladder comprises a first inner section having a first inner right rail, a first inner left rail in parallel and spaced relation with the first inner right rail and a plurality of first inner rungs attached to the first inner left and right rail. The ladder comprises a first articulated hinge attached to the first inner right rail with a first set of fasteners. The ladder comprises a second articulated hinge attached to the first inner left rail with a second set of fasteners. The ladder comprises a second inner section having a second inner right rail, and a second inner left rail in parallel and spaced relation with the second inner right rail and a plurality of second inner rungs attached to the second inner left and right rails. The second inner right rail attached to the first articulated hinge and the second inner left rail attached to the second articulated hinge so the second inner section can rotate about the first and second articulated hinges at least 80° relative to the first inner section. The ladder comprises a first outer section having a first outer right rail, and a first outer left rail in parallel and spaced relation with the first outer right rail and a plurality of first outer rungs attached to the first outer left and right rails. The first outer right rail disposed about the first inner right rail with the first inner right rail sliding up and down relative to the first outer right rail, the first outer right rail having a bend of at least 7° outward relative to the first inner right rail which defines a lower portion below the bend. The ladder comprises a first locking bar attached to the first outer section which locks the first inner right rail in place relative to the first outer right rail in a locked state and allows the first inner right rail to slide relative to the first outer right rail in the unlocked state. The ladder comprises a second outer section having a second outer right rail, and a second outer left rail in parallel and spaced relation with the second outer right rail and a plurality of second outer rungs attached to the second outer left and right rails. The second outer right rail disposed about the second inner right rail with the second inner right rail sliding up and down relative to the second outer right rail, the first and second outer right rails and the first and second outer left rails each have a web that is less than 0.041 inches thick. The multipurpose ladder having an ANSI duty rating of at least 1A and supports at least 300 lbs. of load without failing, and passes a cantilever bend test, where a load of 500 lbf is applied at a right angle to a bottom of the first right outer rail of the ladder at a web of the first right outer rail and the first right outer rail of the ladder does not fail.
The present invention pertains to a method for using a multipurpose ladder. The method comprises the steps of moving the ladder to a desired location. There is the step of placing the ladder on ground at the desired location so a user can climb the ladder. The ladder comprises a first inner section having a first inner right rail, a first inner left rail in parallel and spaced relation with the first inner right rail and a plurality of first inner rungs attached to the first inner left and right rail. The ladder comprises a first articulated hinge attached to the first inner right rail with a first set of fasteners. The ladder comprises a second articulated hinge attached to the first inner left rail with a second set of fasteners. The ladder comprises a second inner section having a second inner right rail, and a second inner left rail in parallel and spaced relation with the second inner right rail and a plurality of second inner rungs attached to the second inner left and right rails. The second inner right rail attached to the first articulated hinge and the second inner left rail attached to the second articulated hinge so the second inner section can rotate about the first and second articulated hinges at least 80° relative to the first inner section. The ladder comprises a first outer section having a first outer right rail, and a first outer left rail in parallel and spaced relation with the first outer right rail and a plurality of first outer rungs attached to the first outer left and right rails. The first outer right rail disposed about the first inner right rail with the first inner right rail sliding up and down relative to the first outer right rail. The first outer right rail having a bend of at least 7° outward relative to the first inner right rail which defines a lower portion below the bend. The ladder comprises a first locking bar attached to the first outer section which locks the first inner right rail in place relative to the first outer right rail in a locked state and allows the first inner right rail to slide relative to the first outer right rail in the unlocked state. The ladder comprises a second outer section having a second outer right rail, and a second outer left rail in parallel and spaced relation with the second outer right rail and a plurality of second outer rungs attached to the second outer left and right rails. The second outer right rail disposed about the second inner right rail with the second inner right rail sliding up and down relative to the second outer right rail. The multipurpose ladder comprises a plurality of brackets disposed about the first outer right rail, and the first outer left rail, and the second outer right rail, and the second outer left rail. The brackets providing support to each of the outer right rails and outer left rails and strengthens them against bending forces. The multipurpose ladder having an ANSI duty rating of 1A and supports 300 lbs. of load without failing.
In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which:
Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to
Alternatively, the multipurpose ladder may have a weight to length ratio of less than or equal to 2.3 lbs/ft or 2.25 lbs/ft or 2.17 lbs/ft as a 14′ IAA ANSI duty rated multipurpose ladder, or a weight to length ratio of less than or equal to 2.23 lbs/ft or 2.18 lbs/ft as a 18′ IAA ANSI duty rated multipurpose ladder, or a weight to length ratio of less than or equal to 2.06 lbs/ft as a 22′ IAA ANSI duty rated multipurpose ladder, or a weight to length ratio of less than or equal to 2.3 lbs/ft or 2.25 lbs/ft or 2.19 lbs/ft as a 26′ IAA ANSI duty rated multipurpose ladder, or a weight to length ratio of less than or equal to 1.95 lbs/ft or 1.90 lbs/ft as a 14′ IA ANSI duty rated multipurpose ladder, or a weight to length ratio of less than or equal to 1.94 lbs/ft or 1.88 lbs/ft as a 18′ IA ANSI duty rated multipurpose ladder, or a weight to length ratio of less than or equal to 1.85 lbs/ft or 1.81 lbs/ft as a 22′ IA ANSI duty rated multipurpose ladder, or a weight to length ratio of less than or equal to 1.95 lbs/ft or 1.93 lbs/ft as a 26′ IA ANSI duty rated multipurpose ladder.
Ladders that have an “A” in the rating are heavy duty ladders that can carry heavy loads. IA Ladders can hold up to 300 pounds without failing. This makes it safe to carry a wide range of items up and down the ladder, including heavier items. Some 1A ladders can hold two people at the same time. Type IA ladders are sufficient for most contractor, carpentry, and construction jobs. IAA ladders are the most heavy-duty ladders available. They can support up to 375 pounds without failing. They are great for jobs that require the user to transport extremely heavy items up and down the ladder. ANSI is an acronym for American National Standards Institute. By definition, a ladder that has an ANSI duty rating of IA or IAA has all the necessary features for a user to safely use the ladder and meets all the requirements of the latest ANSI code 2017, incorporated by reference herein. That is, for purposes herein, the weight of the ladder considered for the respective length to weight ratio is the weight of the ladder that has all the necessary features for the ladder to meet all the requirements of the latest ANSI code 2017. By adding brackets 58 in specific locations, the reinforced rails can be lighter weight than is possible without the brackets 58. Furthermore, the MT ladder 10 has achieved a reduced length to weight ratio compared to previously existing MT ladders, and has been realized through the discovery of how to do so while still meeting the requirements and being in conformance with the ANSI code 2017; so, it is not just reducing the weight of any MT ladder but reducing the weight in such a way that a user can safely use the MT ladder 10 because it meets the requirements and is in conformance with ANSI code 2017.
This High Strength MT Ladder 10 has been designed to be the lightest MT ladder in the world and have at least an ANSI rating of IA. To accomplish this, both the inner rail and outer rail walls have been made thinner than existing MT ladders. Additionally, the inner steps, rear cross braces, hinge plates, hinge spacers, and outer feet have been optimized for weight savings by eliminating material or decreasing material thickness in areas where the material is not needed.
The ladder 10 may include a plurality of brackets 58 disposed about the first outer right rail 38, and the first outer left rail 40, and the second outer right rail 52, and the second outer left rail 54. The brackets 58 providing support to each of the outer right rails and outer left rails and strengthens them against bending forces. The brackets 58 are added to the outer rails of MT ladders to add localized strength to the outer rails.
The ladder 10 may include a first bracket 60 of the plurality of brackets 58 disposed about and attached adjacent the top of the first outer right rail 38 above the first locking bar 48. The first bracket 60 having a shape which conforms with a cross sectional shape of the first right outer rail. The first bracket 60 is about 0.5 inches wide and about 0.1 inch thick all around.
The ladder 10 may include a second bracket 62 of the plurality of brackets 58 disposed about the first outer right rail 38 and above and attached adjacent a second highest first outer rung 64 and below the first locking bar 48. The second bracket 62 having a shape which conforms with the cross-sectional shape of the first outer right rail 38.
The ladder 10 may include a third bracket 66 of the plurality of brackets 58 disposed about the first outer right rail 38 and below and attached adjacent the second highest first outer rung 64. The third bracket 66 having a shape which conforms with the cross-sectional shape of the first outer right rail 38. The second and third brackets are about 1 inch wide and 0.1 inch thick all around.
The ladder 10 may include a fourth bracket 68 of the plurality of brackets 58 disposed about and attached adjacent a bottom 70 of the first outer right rail 38. The fourth bracket 68 having a shape which conforms with the cross-sectional shape of the first outer right rail 38. The fourth bracket 68 may be partially covered by a first outer right foot 71 that fits onto the bottom 70 of the first outer right rail 38, as shown in
The ladder 10 may include a lower cross brace 72 attached to the first outer right rail 38 and the first outer left rail 40 adjacent a bottom 70 of the first outer right and left rails, as shown in
The ladder 10 may include a sixth bracket 76 of the plurality of brackets 58 disposed inside the first outer right rail 38 and attached to the first outer right rail 38 below the fifth bracket 74 and above the fourth bracket 68. The sixth bracket 76 having a shape which conforms with the cross-sectional shape of the first outer right rail 38.
The first articulated hinge 20 may include inner and outer hinge spacers which have bolt holes 80 through which bolts 226 extend to attach the first articulated hinge 20 to the first outer right rail 38 which has localized buttressing 84 about each bolt hole, where the buttressing 84 causes the spacers to be thicker than areas where there is no buttressing 84. The buttressing 84 strengthens the inner and outer hinge spacers against cracking or failure from forces applied to the rivets 226. The fourth, fifth and sixth brackets are about 1.5 inches wide and about 0.1 inch thick all around.
Furthermore, as shown in
The first outer right rail 38 may have a web 86 and a first flange 88 extending perpendicularly from the web 86 and a second flange 90 extending perpendicularly from the web 86 and in parallel and spaced relation with the first flange 88, and wherein the first bracket 60 may have a web 86 and a first flange 88 extending perpendicularly from the web 86 and a second flange 90 extending perpendicularly from the web 86 and in parallel and spaced relation with the first flange 88 of the first bracket 60. The web 86 of the first bracket 60 contacts and conforms with the web 86 of the first outer right rail 38, the first flange 88 of the first bracket 60 contacts and conforms with the first bracket 60 of the first outer right rail 38 and the second flange 90 of the second bracket 62 contacts and conforms with the second flange 90 of the first outer right rail 38. Each of the additional brackets 58, second through sixth also have a web 86, a first flange 88 and a second flange 90 which conform with the web 86, first flange 88 and second flange 90 of the first outer right rail 38 in the same way as described with respect to way the first bracket 60 conforms and the first outer right rail 38.
The hinge plates shown in
The present invention pertains to a method for using a multipurpose ladder 10. The method comprises the steps of moving the ladder 10 to a desired location. There is the step of placing the ladder 10 on ground at the desired location so a user can climb the ladder 10. The ladder 10 comprises a first inner section 12 having a first inner right rail 14, a first inner left rail 16 in parallel and spaced relation with the first inner right rail 14 and a plurality of first inner rungs 18 attached to the first inner left and right rail. The ladder 10 comprises a first articulated hinge 20 attached to the first inner right rail 14 with a first set of fasteners 22. The ladder 10 comprises a second articulated hinge 24 attached to the first inner left rail 16 with a second set of fasteners 26. The ladder 10 comprises a second inner section 28 having a second inner right rail 30, and a second inner left rail 32 in parallel and spaced relation with the second inner right rail 30 and a plurality of second inner rungs 34 attached to the second inner left and right rails. The second inner right rail 30 attached to the first articulated hinge 20 and the second inner left rail 32 attached to the second articulated hinge 24 so the second inner section 28 can rotate about the first and second articulated hinges 20, 24 at least 80° relative to the first inner section 12. The ladder 10 comprises a first outer section 36 having a first outer right rail 38, and a first outer left rail 40 in parallel and spaced relation with the first outer right rail 38 and a plurality of first outer rungs 42 attached to the first outer left and right rails. The first outer right rail 38 disposed about the first inner right rail 14 with the first inner right rail 14 sliding up and down relative to the first outer right rail 38. The first outer right rail 38 having a bend 46 of at least 7° outward relative to the first inner right rail 14 which defines a lower portion 44 below the bend 46. The ladder 10 comprises a first locking bar 48 attached to the first outer section 36 which locks the first inner right rail 14 in place relative to the first outer right rail 38 in a locked state and allows the first inner right rail 14 to slide relative to the first outer right rail 38 in the unlocked state. The ladder 10 comprises a second outer section 50 having a second outer right rail 52, and a second outer left rail 54 in parallel and spaced relation with the second outer right rail 52 and a plurality of second outer rungs 56 attached to the second outer left and right rails. The second outer right rail 52 disposed about the second inner right rail 30 with the second inner right rail 30 sliding up and down relative to the second outer right rail 52. The multipurpose ladder 10 having a weight to length ratio of less than 2.41 lbs/ft as a 14′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.27 lbs/ft as a 18′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.08 lbs/ft as a 22′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.34 lbs/ft as a 26′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.0 lbs/ft as a 14′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 18′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 1.90 lbs/ft as a 22′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 26′ IA ANSI duty rated multipurpose ladder. Alternatively, the aforementioned different sized multipurpose ladders may have weight to length ratios as described above.
The present invention pertains to a method for using a multipurpose ladder 10. The method comprises the steps of moving the ladder 10 to a desired location. There is the step of placing the ladder 10 on ground at the desired location so a user can climb the ladder 10. The ladder 10 comprises a first inner section 12 having a first inner right rail 14, a first inner left rail 16 in parallel and spaced relation with the first inner right rail 14 and a plurality of first inner rungs 18 attached to the first inner left and right rail. The ladder 10 comprises a first articulated hinge 20 attached to the first inner right rail 14 with a first set of fasteners 22. The ladder 10 comprises a second articulated hinge 24 attached to the first inner left rail 16 with a second set of fasteners 26. The ladder 10 comprises a second inner section 28 having a second inner right rail 30, and a second inner left rail 32 in parallel and spaced relation with the second inner right rail 30 and a plurality of second inner rungs 34 attached to the second inner left and right rails. The second inner right rail 30 attached to the first articulated hinge 20 and the second inner left rail 32 attached to the second articulated hinge 24 so the second inner section 28 can rotate about the first and second articulated hinges 20, 24 at least 80° relative to the first inner section 12. The ladder 10 comprises a first outer section 36 having a first outer right rail 38, and a first outer left rail 40 in parallel and spaced relation with the first outer right rail 38 and a plurality of first outer rungs 42 attached to the first outer left and right rails. The first outer right rail 38 disposed about the first inner right rail 14 with the first inner right rail 14 sliding up and down relative to the first outer right rail 38. The first outer right rail 38 having a bend 46 of at least 7° outward relative to the first inner right rail 14 which defines a lower portion 44 below the bend 46. The ladder 10 comprises a first locking bar 48 attached to the first outer section 36 which locks the first inner right rail 14 in place relative to the first outer right rail 38 in a locked state and allows the first inner right rail 14 to slide relative to the first outer right rail 38 in the unlocked state. The ladder 10 comprises a second outer section 50 having a second outer right rail 52, and a second outer left rail 54 in parallel and spaced relation with the second outer right rail 52 and a plurality of second outer rungs 56 attached to the second outer left and right rails. The second outer right rail 52 disposed about the second inner right rail 30 with the second inner right rail 30 sliding up and down relative to the second outer right rail 52. The multipurpose ladder 10 comprises a plurality of brackets 58 disposed about the first outer right rail 38, and the first outer left rail 40, and the second outer right rail 52, and the second outer left rail 54. The brackets 58 providing support to each of the outer right rails and outer left rails and strengthens them against bending forces. The multipurpose ladder 10 having an ANSI duty rating of IA and supports 300 lbs. of load without failing.
The present invention pertains to a method for producing a multipurpose ladder 10. The method comprises the steps of assembling the ladder 10 with a first inner section 12 having a first inner right rail 14, a first inner left rail 16 in parallel and spaced relation with the first inner right rail 14 and a plurality of first inner rungs 18 attached to the first inner left and right rail. Attaching a first articulated hinge 20 to the first inner right rail 14 with a first set of fasteners 22. Attaching a second articulated hinge 24 to the first inner left rail 16 with a second set of fasteners 26. The ladder 10 comprises a second inner section 28 having a second inner right rail 30, and a second inner left rail 32 in parallel and spaced relation with the second inner right rail 30 and a plurality of second inner rungs 34 attached to the second inner left and right rails. The second inner right rail 30 attached to the first articulated hinge 20 and the second inner left rail 32 attached to the second articulated hinge 24 so the second inner section 28 can rotate about the first and second articulated hinges 20, 24 at least 80° relative to the first inner section 12. The ladder 10 comprises a first outer section 36 having a first outer right rail 38, and a first outer left rail 40 in parallel and spaced relation with the first outer right rail 38 and a plurality of first outer rungs 42 attached to the first outer left and right rails. The first outer right rail 38 disposed about the first inner right rail 14 with the first inner right rail 14 sliding up and down relative to the first outer right rail 38. The first outer right rail 38 having a bend 46 of at least 7° outward relative to the first inner right rail 14 which defines a lower portion 44 below the bend 46. The ladder 10 comprises a first locking bar 48 attached to the first outer section 36 which locks the first inner right rail 14 in place relative to the first outer right rail 38 in a locked state and allows the first inner right rail 14 to slide relative to the first outer right rail 38 in the unlocked state. The ladder 10 comprises a second outer section 50 having a second outer right rail 52, and a second outer left rail 54 in parallel and spaced relation with the second outer right rail 52 and a plurality of second outer rungs 56 attached to the second outer left and right rails. The second outer right rail 52 disposed about the second inner right rail 30 with the second inner right rail 30 sliding up and down relative to the second outer right rail 52. The multipurpose ladder 10 having a weight to length ratio of less than 2.41 lbs/ft as a 14′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.27 lbs/ft as a 18′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.08 lbs/ft as a 22′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.34 lbs/ft as a 26′ IAA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.0 lbs/ft as a 14′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 18′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 1.90 lbs/ft as a 22′ IA ANSI duty rated multipurpose ladder or a weight to length ratio of less than 2.00 lbs/ft as a 26′ IA ANSI duty rated multipurpose ladder. Alternatively, the aforementioned different sized multipurpose ladders may have weight to length ratios as described above. The rails and rungs and brackets 58 are made of aluminum, and specifically may be either 6061-T6, 6061-T5, or 6005-T5 aluminum alloy.
The present invention pertains to a method for producing a multipurpose ladder 10. The method comprises the steps of assembling the ladder 10 with a first inner section 12 having a first inner right rail 14, a first inner left rail 16 in parallel and spaced relation with the first inner right rail 14 and a plurality of first inner rungs 18 attached to the first inner left and right rail. Attaching a first articulated hinge 20 to the first inner right rail 14 with a first set of fasteners 22. Attaching a second articulated hinge 24 to the first inner left rail 16 with a second set of fasteners 26. The ladder 10 comprises a second inner section 28 having a second inner right rail 30, and a second inner left rail 32 in parallel and spaced relation with the second inner right rail 30 and a plurality of second inner rungs 34 attached to the second inner left and right rails. The second inner right rail 30 attached to the first articulated hinge 20 and the second inner left rail 32 attached to the second articulated hinge 24 so the second inner section 28 can rotate about the first and second articulated hinges 20, 24 at least 80° relative to the first inner section 12. The ladder 10 comprises a first outer section 36 having a first outer right rail 38, and a first outer left rail 40 in parallel and spaced relation with the first outer right rail 38 and a plurality of first outer rungs 42 attached to the first outer left and right rails. The first outer right rail 38 disposed about the first inner right rail 14 with the first inner right rail 14 sliding up and down relative to the first outer right rail 38. The first outer right rail 38 having a bend 46 of at least 7° outward relative to the first inner right rail 14 which defines a lower portion 44 below the bend 46. The ladder 10 comprises a first locking bar 48 attached to the first outer section 36 which locks the first inner right rail 14 in place relative to the first outer right rail 38 in a locked state and allows the first inner right rail 14 to slide relative to the first outer right rail 38 in the unlocked state. The ladder 10 comprises a second outer section 50 having a second outer right rail 52, and a second outer left rail 54 in parallel and spaced relation with the second outer right rail 52 and a plurality of second outer rungs 56 attached to the second outer left and right rails. The second outer right rail 52 disposed about the second inner right rail 30 with the second inner right rail 30 sliding up and down relative to the second outer right rail 52. The multipurpose ladder 10 comprises a plurality of brackets 58 disposed about the first outer right rail 38, and the first outer left rail 40, and the second outer right rail 52, and the second outer left rail 54. The brackets 58 providing support to each of the outer right rails and outer left rails and strengthens them against bending forces. The multipurpose ladder 10 having an ANSI duty rating of IA and supports 300 lbs. of load without failing.
Each outer rail has a web 86 that is thinner than 0.041 inches thick, with more than 80% of the web 86 having a rounded surface, as shown in
Preferably, each outer rail has a web 86 that is 0.040 inches thick for maximum weight savings for the 14IAA, 18IAA and 22IAA MT ladders, where the 14, 18 and 22 identify the height of the MT ladder 10 in feet, respectively. More than 80% of the web has a rounded surface which allows for internal reinforcement and a more comfortable grip by a user. Preferably each outer rail has a height that is 3.27 inches long, a cross section that is 0.279 in{circumflex over ( )}2, and a ly that is 0.473 in{circumflex over ( )}4. The first flange 88 and second flange 90 of the outer rail are 0.051 inches thick.
Each inner rail has a cross-section of a hollow box and has a web 92 that is thinner than 0.041 inches thick, and a height that is at least 2.8 inches long, with a cross section that is less than 0.41 in{circumflex over ( )}2 and a ly that is greater than 0.5 in{circumflex over ( )}4, as shown in
There is a reinforcement plate 98, as shown in
The reinforcing plate 98 was added to the inside of each of the outer rails on the 22IAA and 26IAA models in order to pass the ANSI Single J Lock Test. Moving the material to the ends of the reinforcement plate 98 achieves the needed strength but allows the part to be low profile and fit inside of the outer rail without interfering with the operation of the ladder. The reinforcement plate 98 is disposed on the inside of the outer rail and conforms to the shape of inner surface of outer rail. The reinforcing plate 98 has an upper section 100 that extends about 1.5 inches from above a bend 102, and a lower section 104 that extends about 6.5 inches below the bend 102. The reinforcing plate 98 has a web 106 which is about 0.040 inches thick and a curvature that conforms with and is essentially the same as the curvature of web 86 of the outer rail. The outer rail has an upper section 112 and a lower section 114 and a bend 116 therebetween, and the upper section 100 and the lower section 104 and the bend 102 of the reinforcing plate 98 fits inside the corresponding sections of the outer rail. The reinforcing plate 98 is made of Aluminum 6061-T6, 6005-T5 or an engineering equivalent.
At least one inner rung comprises a hollow center portion 118; a top web 120 which extends upwards from the center portion 118, and a top flange 122 having a flat surface 124 on which a user can place a foot to stand on, as shown in
The inner web 92 of the first inner right rail 14 and the first inner left rail 16 has a first hole 130 and a second hole 132 and a third hole 134 and a fourth hole 136, as shown in
The inner rung has been optimized to move material away from the centroid of the part (thinner webs and swage, thicker flanges) to facilitate a lighter weight design that still passes ANSI codes for step strength. Additionally, there are four nubs at the end of the inner rung that engage holes in the inner rail. Without this engagement, the step collapses during the step-to-side rail shear ANSI test.
The hinge comprises an outer hinge plate assembly 200, as shown in
The left and right inner and outer hinge plates and spacers each have a stem 224, as shown in
The hinge plate thicknesses were minimized to reduce weight. In order to pass ANSI testing, two design changes regarding the hinge were required.
1) The hinge plate alloy of the 18′, 22′, and 26′ ladders was changed from 6061-T6 to 7N01-T5 which is a stronger alloy.
2) Spacers were added to maintain distance between the hinge plates. This improves the I value of the assembly in the horizontal direction.
Cutouts 240 were added to the hinge plates to remove material in locations where it was unneeded for strength in order to lighten the parts. The 14 foot and 18 foot MT ladders 10 use semi-tube 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 higher stresses experienced during testing.
A J lock reinforcing plate 242 made of metal, such as aluminum, has a J lock plate hole 244 and is attached with rivets 226 to the inside of the outer rail so the J lock plate hole 244 aligns with the J lock outer rail hole 246 so the J lock fits in and extends through the J lock plate hole 244 and the J lock outer rail hole 246, as shown in
Tests that are required for the MT ladder to pass to be ANSI IAA rated, besides being able to support loads of 375 lbs., include the following:
Step-to-siderail shear test: 1200 lbf applied for 60 sec to the side of each rung that has a different profile and no component of the ladder fails. Ladder in step ladder mode.
Single lock (J lock) test: 1200 lbf applied for 60 sec evenly to rung immediately above the J lock and no component of the ladder fails. Ladder in full extension mode and leaning against a wall.
Horizontal bend ultimate 1 position: 460 lbf applied for 60 sec to the rung closest to the center of the ladder 10 and no component of the ladder fails. Ladder in full extension mode and supported horizontally at both ends.
Column and hardware load test: 1500 lbf applied for 60 sec to the top rung of the ladder 10 and no component of the ladder fails. Ladder in full extension mode and leaning against a wall.
Cantilever bend test: Test load is 500 lbf for IA and 600 lbf for IAA and is applied at a right angle to the bottom 70 of the first right outer rail 38 of the ladder 10 at the web 86, as shown in
The MT ladder 10 passes all of these tests.
Examples of multipurpose ladders 10 with a weight to length ratio are as follows:
Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.
This is a non-provisional of U.S. provisional patent application Ser. No. 62/677,443 filed May 29, 2018, which is a continuation-in-part of U.S. patent application Ser. No. 15/883,958 filed Jan. 30, 2018, both of which are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62677443 | May 2018 | US |
