This invention relates to manhole steps and ladders, more specifically, the present invention relates to two-sided manhole steps.
Pre-cast concrete manholes are widely used throughout the world to provide access to storm and sanitary sewer systems and a variety of other below-ground installations of piping, cables and the like. For such accesses to be used, a ladder or steps must be provided to permit workers to descend into and climb out of the manhole. A variety of structures have been employed to make this possible, including temporarily positioning ladders in the manhole and permanently attaching ladders or steps to the inside wall of the manhole.
One such step is disclosed in U.S. Pat. No. 4,100,997, which is incorporated herein by reference. U.S. Pat. No. 4,100,997 describes a steel reinforced plastic step that is injection molded of copolymer polypropylene. Support members that terminate at ends having molded, deformable annular projections are driven into preformed holes in the inside wall of the manhole. The disclosed step of U.S. Pat. No. 4,100,997 has an upper flat step surface attached to the two support members. At each end of the flat support surface is an upward projection member that projects at approximately 90° from the flat step surface.
Such upward projection members ensure that the manhole step complies with OSHA Standard No. 1910.27(b)(1)(v), which requires that the “rungs of an individual-rung ladder shall be so designed that the foot cannot slide off the end.”
A problem occurs when manhole steps are installed and due to the installation process the steps are installed upside down. When steps such as the one shown in U.S. Pat. No. 4,100,997 or the one shown in
Embodiments of the present invention include a two sided step which includes a first step surface, a second step surface, at least one attachment member for securing the step to a structure, first and second lugs extending substantially perpendicular from ends of the first step surface, and third and fourth lugs extending substantially perpendicular from ends of the second step surface.
Each end of the step support members is provided with a means 22, 24 for retaining the step 10 in place in tapered holes or bores formed in the concrete wall of a manhole or other desired structure. Each end can be identical or similar in construction and can be molded to include a plurality of evenly spaced circular projections which may be smaller or less in diameter from one another such that the means 22, 24 taper towards distal ends. The operation of the ends is described in more detail in U.S. Pat. No. 4,100,997. Other means for retaining the step in concrete known to those skilled in the art can be used.
Both ends of the step member 12 have integrally formed lugs 26, 28, 34 and 36 that project outwardly from the first step surface 14 and project outwardly from the second step surface 16. As shown in
The lugs 26, 28, 34 and 36 can facilitate prevent a user's foot from slipping off a side of the step 10.
In the embodiments shown in
In the embodiments shown in
To install the step 10, two tapered openings or bores are first drilled into a wall of the manhole or other structure using a drill or other suitable means. In another embodiment, the openings are preformed in the wall. Next, the ends of the step support members are aligned with the respective openings and then hammered in place by a mallet or small sledge hammer, causing the circular projections to deform and securely hold the step 10 in the openings. Because the step 10 is symmetric with respect to its first and second step surfaces and associated lugs, the manhole step of the present invention can be installed with either step surface facing upwardly, so that it cannot be installed upside down.
As those skilled in the art will appreciate, the particular embodiment of this invention described above and illustrated in the figures is provided for explaining the invention, and various alterations may be made in the structure and materials of the illustrated embodiment without departing from the spirit and scope of the invention as described above.
This application relates to and claims the benefit of U.S. Provisional Application No. 60/488,187, filed Jul. 17, 2003 and entitled “Two-Sided Manhole Step”, which is hereby incorporated in its entirety by this reference.
Number | Date | Country | |
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60488187 | Jul 2003 | US |