Fire escape – ladder – or scaffold – Convertible – Ladder
Reexamination Certificate
2001-09-17
2003-03-18
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Convertible
Ladder
C182S209000
Reexamination Certificate
active
06533068
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is directed to conventional household ladders, and more particularly to a ladder that can be used as either a stepladder or an extension ladder.
2. Description of the Art
The household ladder has become an essential item around the house. The ladder is needed for gaining access to many areas. The roof areas as well as roof drains must be frequently inspected, cleaned and repaired. Some home owners also prefer to do their own painting and repair work on the exterior of the home. The ability of the homeowner to do these jobs has been made easier by the invent of new tools and equipment, such as economical paint sprayers. An extension ladder is generally used for this purpose and various other asks which require additional ladder length over the stepladder. The stepladder is needed where a vertical surface is not available to rest the upper end of the extension ladder. These tasks are more common to the interior of the house for painting, repair work, replacing light bulbs and the like. As a result, the needs for a ladder usually means the homeowner must purchase both a stepladder and an extension ladder to be able to safely perform all the required homeowner tasks. The homeowner needs a single ladder that can easily be converted from a stepladder to an extension ladder. The various jobs of a contractor also accent the needs for both a stepladder and an extension ladder. The contractor must transport from job to job both ladder types and ladders of different size to have the correct ladder at each job. The combination ladder of this invention provides the needs for both the homeowner and the contractor.
Stepladders have been converted into other tools commonly used by the homeowner or contractor. For example, the combination tool of U.S. Pat. No. 5,836,595 has a first position for providing a stepladder which is converted into a second configuration to become a handtruck. A number of conversion kits and multifunction ladders have been provided in the industry to address the needs of the homeowner and the contractor. Devices for converting an extension ladder into a step ladder are disclosed in U.S. Pat. Nos. 4,043,423 and 5,673,885. These devices include one or more support braces for holding the side rails of the extension ladder together to form an A-frame stepladder. Support braces are separate structural components that clamp or hold the side rails in the stepladder configuration. Therefore, the support braces as well as the paint tray are separate devices that must be stored until they are used to convert the extension ladder into a stepladder.
A “Multi-Use Ladder System” maketed by Cosco of Columbus, Ind. a subsidiary of Dorel Industries, Inc. of Montreal, Canada is sold by Sam's Club in their various wholesale outlet stores. This ladder has two extension ladder sections connected by a swivel device which allows the two ladder sections to either extend in a line with one another similar to an extension ladder or to form an A-fame shape to provide a stepladder. The swivel connecting device has a locked and an unlocket positions to move the ladder from one configuration to the other by rotating the two sections with respect to one another about the swivel device. This multi-use ladder is not a convention ladder with regard to how it operates or how it may be used. In addition, this ladder system does not appear to provide for braces when used as a stepladder.
The need remains to provide a combination extension ladder which easily converts into a stepladder as desired. The desire is to have an extension ladder and a stepladder which are somewhat conventional in the industry. There should be nothing new of different in either configuration that requires the user to adjust to what is standard and easily to use.
Accordingly, an object of the present invention is to provide a ladder that can easily be converted from a stepladder to an extension ladder and back to a stepladder as needed with little effort.
Another object of the present invention is to provide low cost connection assemblies that can be added to conventional ladder sections to provide the extension ladder or the stepladder with a paint tray and braces.
Yet another object of the present invention is to provide a single ladder for multiple use around the house without the need to have two ladders.
Still another object of the present invention is to provide a combination ladder with the safety, strength and durability of the conventional stepladder and the conventional extension ladder.
SUMMARY OF THE INVENTION
The above objectives are accomplished according to the present invention by providing a combination ladder which can easily be converted to provide either an extension ladder configuration or a stepladder configuration. First and second ladder sections are used which are generally conventional in the industry with side rails and rungs between the side rails. The ladder sections are generally of the same size and the flanges of the side rails are placed adjacent to one another. A pair of upper connection assemblies are provided at the top ends of the side rails and a pair of lower connection assemblies are provided at the lower ends of the side rails. Each connection assembly has a connector that is changed from a first position to a second position to convert the ladder from one configuration to the other configuration. A pair of brace assemblies provide a lateral brace for the stepladder. A paint shelf can also be provided for use with either ladder configuration.
In one embodiment of the invention a combination ladder is provided including first and second conventional ladder sections each having upper and lower ends alternately connected together to provide a stepladder configuration or an extension ladder configuration. The combination ladder comprises a pair of upper connection assemblies for connecting the upper ends of the ladder sections together. Each upper connection assembly includes an upper slide unit, an upper support plate, an upper stop plate, a hinge pin and an upper connector for connecting the upper slide unit to either one of the upper support plate or the upper stop plate. A pair of lower connection assemblies connect the lower ends of the ladder sections together. Each lower connection assembly including a lower slide unit, a lower support plate, a lower stop plate and a lower connector for connecting the lower slide unit to either one of the lower support plate or the lower stop plate. The upper and lower connectors have a first position for attaching both upper slide units to a respective upper support plate and both lower slide units to a respective lower support plate. The first ladder section is free to move parallel to the second ladder section to provide the extension ladder configuration. The upper and lower connectors have a second position for attaching both upper slide units to a respective upper stop plate and both lower slide units to a respective lower stop plate. Therefore, the upper end of the first ladder section is rotateably attached to the upper end of the second ladder section and the lower end of the first ladder section is free to move transverse to the lower end of the second ladder section to provide the stepladder configuration.
In a second embodiment of the invention a ladder assembly provides either one of a stepladder or an extension ladder. The ladder assembly comprises first and second conventional ladder sections each having a pair of side rails with upper and lower ends and evenly spaced apart rungs extending between said each pair of side rails. A pair of upper connection assemblies are associated with the upper ends of the side rails. The upper connection assemblies each have an upper slide unit for holding the side rails of the first and second ladder sections adjacent one to the other, so that the first ladder section can be displaced relative to the second ladder section. A pair of lower connection assemblies are associated with the lower ends of said side rails. The lower connect
Chin-Shue Alvin
Patent Consultants & Services, Inc.
Reed Robert R.
LandOfFree
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