A portable ladder having arcuate rungs and is deployable through a hatchway of a tank.
Tanks for containing liquids are often mounted on a railcar, a semi-trailer, or other vehicle for transporting liquids, often in large volumes. Human access to the tank is provided through a hatchway on a top of the tank. The vertical distance from the hatchway to a bottom wall of the tank can be large enough to require a ladder to safely traverse this distance. The inner chamber of a tank must be accessed, from time to time, for cleaning, inspection and maintenance. Accordingly, the present invention provides a ladder that can be deployed through the hatchway of the tank and secured thereto for safe access and removed upon exit from the tank.
A portable ladder is disclosed having a pair of spaced elongate stiles extending generally parallel to one another and connected together by a plurality of rungs extending along a line generally perpendicular to the stiles and spaced from one another along a length of the stiles. The rungs extend along an arcuate path from one opposed end to another.
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated.
The stiles are elongate, having a length dimension greater than a width and a depth dimension, and can have a variety of shapes in horizontal cross section such as a straight line, a curved line, a letter shape, a C-shape, a D-shape, an H-shape, a T-shape, an L-shape, a V-shape, circular, oval, polygonal, irregular, and sinusoidal. Polygonal shapes include triangular, square, rectangular, trapezoidal, pentagonal, hexagonal, heptagonal, and octagonal. Most preferably, the stile is a square tube having an inner face 20, an outer face 22, a front face 24, a back face 26 and defines an inner channel 28. The inner face 22 has a plurality of spaced holes 30 dimensioned to receive an end portion 32 of a rung 14. The hole preferably extends through the entire thickness of the stile 12, and the end portion 32 of the rung will be permanently affixed to the stile by a weld, solder joint, adhesive, bracket or fastener. The hole 32 can also extend through the front face and the back face and the end portion of the rung can be permanently affixed to the front face, back face, or both. The inner channel 28 can be empty or can be filled with a lightweight material such as a foamed polystyrene, foamed polypropylene, or other material, to provide sound dampening, strength and increase buoyancy. In another form of the invention, the rungs will be attached directly to the inner face 20 (no holes 30) by weld, solder joint, adhesive, or indirectly through a bracket, or collar, or through both direct and indirect connections.
The rungs are elongate, having a length dimension greater than a width, a depth dimension or a diameter, and can also have a variety of shapes in cross section such as a straight line, a curved line, a C-shape, a D-shape, an H-shape, a T-shape, an L-shape, a V-shape, circular, oval, polygonal, irregular, and sinusoidal. Polygonal shapes include triangular, square, rectangular, trapezoidal, pentagonal, hexagonal, heptagonal, and octagonal. Most preferably, the rungs will have a circular shape in cross section. The rungs have an arcuate shape and a radius of curvature from one end to the other end. In a preferred form of the invention the radius of curvature of about 15¼ inches for a rung 12⅞ inches long. A portion 36 of each rung 14 extends outward beyond the outer face 22 of the stiles.
The arms 16 are elongate, having a length dimension greater than a width dimension, a depth dimension or a diameter, and can have a variety of shapes in cross section such as a straight line, a curved line, a C-shape, a D-shape, an H-shape, an L-shape, a V-shape, circular, oval, polygonal, irregular, and sinusoidal. Polygonal shapes include triangular, square, rectangular, trapezoidal, pentagonal, hexagonal, heptagonal, and octagonal. In one preferred form of the invention, the arms will have a square shape in cross section (
The gusset 18 preferably is generally three sided and preferably is triangular in shape and preferably in the form of a right triangle. One leg of the triangle will be permanently attached to a portion of the outer face 22 and extend at the same angle α or parallel to the arm and will have a second leg permanently attached to a bottom portion of the arm. The term permanently affixed or attached includes a connection by a weld, solder joint, adhesive, bracket or fastener.
While
The support bar 117 can have a variety of shapes in horizontal cross section such as a straight line, a curved line, a C-shape, a D-shape, an H-shape, an L-shape, a V-shape, circular, oval, polygonal, irregular, and sinusoidal. Polygonal shapes include triangular, square, rectangular, trapezoidal, pentagonal, hexagonal, heptagonal, and octagonal. In one preferred form of the invention, the support bar will have a circular shape in horizontal cross section. Additionally, in a preferred form of the invention, the support bar 117 will be arcuate in shape between opposed ends and will have a centrally disposed curved section 130. The support bar has two sections that extend beyond the stiles located at opposed ends of the support bar to form mounting flanges 131. The curved section also extends beyond the stiles and forms a third mounting flange 133.
In a preferred form of the invention, the gussets 119 are generally triangular and more preferably right triangles and connect a bottom surface of the support bar 117 to an outer surface of the stiles. Preferably, each pair of the gussets 119 is permanently attached to the stiles and the bases of each pair of adjacent gussets are generally in alignment with one another.
The three pins 121 are connected to a bottom surface of the support bar 117 and extend perpendicularly therefrom. The three pins and are spaced from one another with two of the pins 121 being positioned at opposed distal ends of the support arm and the third pin is centrally located at the curved section 130 of the connector bar. The three pins 121 are generally cylindrical with the centrally located pin having a diameter larger than a diameter of the pins located at the distal ends of the support bar. In one preferred form of the invention, the central pin will have a diameter of 1 inch and the distal pins will have a diameter of ½ inch and all of the pins will be two inches in length. The three pins engage the hatchway 46 with the two smaller pins contacting an inner surface of the hatchway 46 and the larger pin engaging an outer surface of the hatchway.
The strap 123 has opposed ends connected to one of each of the stiles below the apexes of the gussets, on a front (
In an embodiment where the securing assembly 115 is releasably attached to the top segment 202, the securing assembly has two connector tubes (not shown) attached to a bottom surface of the support bar and extend in a perpendicular direction away from the bar. The gussets connect the connector tubes to the support arm instead of to the stiles. A hole at a distal end of each connector tube is brought into alignment with respective holes on a top end of each of the stiles and the parts are releasably connected together using the clevis pin assemblies in the same fashion as the ladder segments are connected as discussed above.
The dimensions of the ladder can vary based on the need and application. Typically, the ladder will have sufficient height to extend from a top of a tank to a bottom surface of a tank to provide safe access by a person using the ladder. The ladder can be stowed, for example, on a tanker truck, service vehicle or in a garage or other storage area.
In a preferred form of the invention, the stiles, arms and rungs will be made from a material suitable for use as a ladder and capable of supporting the weight of an adult person of, for example, 250 pounds, and can include, metal, fiberglass, composite materials, wood, polymeric materials and combinations of the same. Suitable metals include aluminum and steel, and preferably is aluminum. The parts can be manufactured by any suitable method such as extrusion and molding or other technique well known to those of ordinary skill in the art. In one preferred form of the invention, the rungs will have traction enhancing modifications such as a textured surface, knurls 220 and or non-slip paint.
While the present invention is described in connection with what is presently considered to be the most practical and preferred embodiments, it should be appreciated that the invention is not limited to the disclosed embodiments, and is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the claims. Modifications and variations in the present invention may be made without departing from the novel aspects of the invention as defined in the claims. The appended claims should be construed broadly and in a manner consistent with the spirit and the scope of the invention herein.
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