The present invention is directed to safety cages for ladders and more specifically to collapsible ladder cages and collapsible ladder cage systems.
The current OSHA regulation for ladders (29 CFR 1910.27) requires that fixed ladders over 20 feet in length be equipped with cages or ladder safety devices. The bottom cage unit must have a larger diameter at the lower end than at the upper end of the unit and the bottom edge of the unit must be located a minimum of 7 feet and a maximum of 8 feet above the ground. OSHA requires that the cages must not extend less than 27 or more than 28 inches from the centerline of the rungs of the ladder and must not be less than 27 inches in width.
Cages are typically formed from a plurality of U-shaped horizontal members to which a plurality of vertical metal structural members are attached at the circumference of the U-shaped members to form a cage-like arrangement in case a worker falls while on the ladder. The most common cages are welded rigid one-piece assemblies designed for attachment to fixed ladders. Standard cage lengths are typically from 7 to 27 feet in which a series of cages can be stacked on a fixed ladder. U.S. Pat. No. 5,255,758 describes a safety cage assembly for a ladder and welded steel cages for use on a fixed ladder are available from the Bondor Manufacturing Company in Providence, R.I.
A collapsible safety guard for derrick ladders is described in U.S. Pat. No. 2,539,664 in which a series of spaced-apart U-shaped angle iron brackets have spaced-apart openings through which a series of chains are threaded. The safety guard of the '664 patent is secured directly to the derrick rather than the ladder and is constructed such that it only need be partially disassembled when the derrick is moved from one location to another.
Currently in the scaffolding industry, ladders between scaffolding platforms are un-caged because according to OSHA requirements, these are temporary ladders and thus do not require cages. This leaves workers on scaffolding structures at great risk because caged ladders are very heavy and difficult to install on temporary scaffold structures.
It would be desirable to have a flexible collapsible ladder cage that is light weight yet can be easily secured to both temporary and fixed ladders. It would further be desirable to have a ladder cage for temporary ladders that meets OSHA's requirements for fixed ladders.
The present invention is directed to a collapsible ladder cage segment comprising at least one rigid U-shaped support member positioned proximate the upper end of the cage segment and a plurality of flexible U-shaped support members. The rigid support member and the plurality of flexible support members are generally in a spaced parallel alignment with each other. A plurality of flexible longitudinal members are positioned in spaced relationship around the circumference of the rigid and flexible U-shaped support members, and are substantially normal to the U-shaped support members, forming a cage-like arrangement. There is a securing assembly on at least one rigid U-shaped support member for securing the rigid support member to a portion of a ladder. The unsecured ladder cage segment is capable of collapsing on itself for transportation and storage.
The present invention is also directed to a collapsible ladder cage system comprising a first cage segment and at least a second cage segment. The first cage segment has an upper rigid U-shaped support member and a lower rigid U-shaped support member. A plurality of flexible support members are spaced between the upper and lower rigid support members generally in a spaced substantially parallel alignment with each other. A plurality of flexible longitudinal members are positioned in spaced relationship around the circumference of the rigid and flexible support members and are substantially normal to the support members, forming a cage-like arrangement. The lower rigid support member has a larger diameter (and hence a larger circumference) than the upper rigid support member. This results in a flared opening. The at least second cage segment has an upper rigid U-shaped support member and a lower rigid U-shaped support member, in which a plurality of flexible support members are spaced between the upper and lower rigid support members generally in a spaced substantially parallel alignment with each other. A plurality of flexible longitudinal members are positioned in spaced relationship around the circumference of the rigid and flexible support members and are substantially normal to the support members, forming a cage-like arrangement. Both cage segments have securing assemblies on at least one of the rigid U-shaped support members for securing the cage segments to a portion of a ladder. It should be understood that the first cage segment having the lower rigid support member with the larger diameter may be the only segment used, and generally would be the lower cage segment used in a multi-cage segment assembly.
The first cage segment is positioned at the bottom of the ladder and the second cage segment is positioned on the ladder a spaced apart distance above the first cage segment. It is contemplated that a plurality of second cage segments can be utilized in the system. Each of the cage segments, once unsecured, are capable of collapsing on itself for transportation and storage. If a plurality of cage segments are used, the present invention describes a collapsible cage system.
The collapsible ladder cage segments of the present invention meet the OSHA regulation for fixed ladders.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
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A plurality of flexible longitudinal members 16 are positioned in spaced relationship around the circumference of the support members 12, 14, substantially normal to the support members 12, 14, forming a cage-like arrangement. In one embodiment, the number of longitudinal members 16 can range from six to twelve depending one the diameter of the rigid support members 12, 14. In a preferred embodiment, the number of longitudinal members 16 can range from eight to twelve. The flexible longitudinal members 16 spaced around the circumference of the support members 12, 14 allow the unsecured ladder cage segment 10 to collapse on itself for transportation and storage. Since the diameter, and hence the circumference, of support member 12d is larger than support members 12a and 12b, the cage segment 10a provides a flared section 10e (
The flexible support members 14 and the flexible longitudinal members 16 can be formed from material such as nylon, cable formed from metal or a synthetic material or chain formed from metal. The rigid support members 12 are typically formed from metal such as steel.
In one embodiment of the collapsible ladder cage system 42, the first cage segment 10a is positioned at the bottom of the ladder 18 and the at least one second cage segment 10 is positioned on the ladder a spaced apart distance above the first cage segment 10a (
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Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.