The present invention is related to a brace rail shield combination that is one continuous piece. More specifically, the present invention is related to a brace rail shield combination that is one continuous piece which has a metal plate and holds a safety shoe.
The current extension ladder knee brace is shown in
The present invention pertains to a brace rail shield combination for a rail of a ladder having at least one rung. The brace rail shield combination comprises a first portion that has a shape that conforms with an interior cross sectional surface of the rail. The brace rail shield combination comprises a second portion that extends from the first portion at a first location to the rung to provide structural support to the rung. The second portion having an attachment portion at a second location spaced apart from the first location that is fixed to the rung. The first portion and the second portion being one continuous piece.
The present invention pertains to a method for using an extension ladder. The method comprises the steps of moving the extension ladder to a structure. There is the step of leaning the extension ladder against the structure so weight on a ladder is distributed to the knee brace rail shield combination connected to a bottom of each rail of the ladder. The knee brace rail shield combination comprising a first portion that has a shape that conforms with an interior cross sectional surface of the rail; and a second portion that extends from the first portion at a first location to the rung to provide structural support to the rung. The second portion having an attachment portion at a second location spaced apart from the first location that is fixed to the rung. The first portion and the second portion being one continuous piece.
The present invention pertains to a method for producing a knee brace rail shield combination. The method comprises the steps of placing a metal plate into a mold of the knee brace rail shield combination. There is the step of injection molding plastic into the mold to form the knee brace rail shield combination comprising a first portion that has a shape that conforms with an interior cross sectional surface of the rail; and a second portion that extends from the first portion at a first location to the rung to provide structural support to the rung. The second portion having an attachment portion at a second location spaced apart from the first location that is fixed to the rung. The first portion and the second portion being one continuous piece with the metal plate embedded in the second portion.
In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which:
a is a perspective view of the first embodiment of a brace rail shield combination of the present invention.
b is a perspective view of a second embodiment of the brace rail shield combination of the present invention.
a is a side view of the brace rail shield combination.
b is an overhead view of the brace rail shield combination.
c is a bottom view of the brace rail shield combination.
Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to
Preferably, the brace rail shield combination 6 includes a metal plate 3 in the first portion 56. The metal plate 3 can be embedded or inserted into the first portion 56. The first portion 56 and second portion 58 are preferably made of plastic. Preferably, the second portion 58 forms an angle of between 5 and 85 degrees with the first portion 56. The second portion 58 preferably has a first face 68 which resists twisting that extends from a top edge 72 of the first portion 56, and a second face 70 extending perpendicularly from the first face 68 along the first face 68 and from the first portion 56.
Preferably, the second portion 58 includes a buttress 23 that extends from the second face 70 and the first portion 56. The first portion 56 preferably has a shoulder bolt hole 74 for a shoulder bolt 11 to hold a safety shoe 8 to the first portion 56. Preferably, the first portion 56 has ribs along the bottom of the first portion 56 to absorb forces while the ladder 13 is in use.
The present invention pertains to a method for using an extension ladder 13. The method comprises the steps of moving the extension ladder 13 to a structure. There is the step of leaning the extension ladder 13 against the structure so weight on a ladder 13 is distributed to the knee brace rail shield combination 6 connected to a bottom of each rail 5 of the ladder 13. The knee brace rail shield combination 6 comprising a first portion 56 that has a shape that conforms with an interior cross sectional surface 60 of the rail 5; and a second portion 58 that extends from the first portion 56 at a first location 62 to the rung 4 to provide structural support to the rung 4. The second portion 58 having an attachment portion 64 at a second location 66 spaced apart from the first location 62 that is fixed to the rung 4. The first portion 56 and the second portion 58 being one continuous piece.
The present invention pertains to a method for producing a knee brace rail shield combination 6. The method comprises the steps of placing a metal plate 3 into a mold of the knee brace rail shield combination 6. There is the step of injection molding plastic into the mold to form the knee brace rail shield combination 6 comprising a first portion 56 that has a shape that conforms with an interior cross sectional surface 60 of the rail 5; and a second portion 58 that extends from the first portion 56 at a first location 62 to the rung 4 to provide structural support to the rung 4. The second portion 58 having an attachment portion 64 at a second location 66 spaced apart from the first location 62 that is fixed to the rung 4. The first portion 56 and the second portion 58 being one continuous piece with the metal plate 3 embedded in the second portion 58.
In the operation of the invention, the brace rail shield combination 6, as shown in
The purpose of the brace rail shield combination 6 is to speed up the assembly process and eliminate unnecessary components. The one piece plastic part 2, with metal plate 3 eliminates the need for the current plastic knee brace 15 and separate aluminum rail shield 17.
The main component of the brace rail shield combination 6 is the molded plastic part 2. Attached to this part is a metal backup plate 3. The back up plate 3 adds a surface to upset rivets 7, abrasion resistance, and extra support to the plastic part 2. The plastic material must have high impact strength, good abrasion resistance, and be nonconductive. The material chosen is a high impact polypropylene. A variety of other materials will accomplish the strength requirements, such as Nylon, filled polymers, and co-polymers.
When the ladder 13 is in the ANSI required 75.5 degree incline position, the brace rail shield combination 6 is resting with the rounded bottom 21 in contact with the shoe 8. The applied load to the ladder 13 is between 800 and 1200 lb depending on the duty rating of the ladder 13. The resultant downward load is placed on the ladder 13 so that the force goes through the four rivets 7 and is dispersed through the bottom of the brace rail shield combination 6 at the rounds 21. The brace rail shield combination 6 is designed to distribute the downward load evenly with minimal stress concentrations. This is aided by the integration of the plastic rail 5 shield and brace for added strength. When dropped on its side from a given height, the sideways force on the brace rail shield combination 6 is absorbed by the plastic part 2 and not by the side rail 5. The brace rail shield combination 6 will withstand breaking when dropped repeatedly to simulate use in the field.
The brace rail shield combination 6 is designed with thick ribs 22 located near the rounds 21 at the bottom. The ribs 22 on the brace rail shield combination 6 absorb forces applied while the ladder 13 is in use and impact forces if the ladder 13 is dropped. The brace rail shield combination 6 also resists twisting of 5 through the utilization of the strong plastic cross ribs 22 FIG. 2. The buttress 23 at the top of the brace rail shield combination 6 is designed to attach to the rung 4 and then direct the forces applied to rung 4 through the four rivets 7 and the bottom of the brace rail shield combination 6. The forces applied to the rung 4 are then distributed through the brace rail shield combination 6 instead of through the rung-to-rail connection 9. The top of the brace rail shield combination 6 is designed with wings 24 on either side to resist twisting of rail 5 and add over all strength.
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 divisional of U.S. patent application Ser. No. 12/456,977 which was filed on Jun. 25, 2009 now U.S. Pat. No. 8,033,363, which is a divisional of U.S. patent application Ser. No. 10/946,743 which was filed on Sep. 21, 2004, now U.S. Pat. No. 7,837,010 which issued on Nov. 23, 2010.
Number | Name | Date | Kind |
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2864544 | Scheidegger | Dec 1958 | A |
5458463 | Chiang | Oct 1995 | A |
5791439 | Plotner et al. | Aug 1998 | A |
Number | Date | Country | |
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20120048650 A1 | Mar 2012 | US |
Number | Date | Country | |
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Parent | 12465977 | Jun 2009 | US |
Child | 13317011 | US | |
Parent | 10946743 | Sep 2004 | US |
Child | 12465977 | US |