Patent Publication Number: US-2013248289-A1

Title: Method For Producing a Combo Brace Rail Shield

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. patent application Ser. No. 13/317,011 filed Oct. 6, 2011, which 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 issued on Oct. 11, 2011, 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. 
    
    
     FIELD OF THE INVENTION 
     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. 
     BACKGROUND OF THE INVENTION 
     The current extension ladder knee brace is shown in  FIG. 7 . It consists of six rivets, one plastic brace, and one extruded aluminum rail shield. The assembly is riveted through the shield, fiberglass rail, and plastic brace. The top of the brace is riveted to the bottom rung of the extension ladder. When the ladder is being used, the load goes through the rail and rivets and is transferred into the plastic brace and aluminum rail shield. The bottom edge of the aluminum rail shield transfers the load into the safety shoe. 
     SUMMARY OF THE INVENTION 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which: 
         FIG. 1   a  is a perspective view of the first embodiment of a brace rail shield combination of the present invention. 
         FIG. 1   b  is a perspective view of a second embodiment of the brace rail shield combination of the present invention. 
         FIG. 2  is a perspective inside view of the brace rail shield combination in place in a rail of a ladder. 
         FIG. 3  is a perspective outside view of the brace rail shield combination in place with a rail of the ladder. 
         FIG. 4   a  is a side view of the brace rail shield combination. 
         FIG. 4   b  is an overhead view of the brace rail shield combination. 
         FIG. 4   c  is a bottom view of the brace rail shield combination. 
         FIG. 5  is a front view of the portion of the ladder with the brace rail shield combination. 
         FIG. 6  is a perspective view of an extension ladder having the brace rail shield combination. 
         FIG. 7  is a perspective view of a prior art knee brace and rail shield on a ladder rail. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to  FIGS. 2 ,  3  and  6  thereof, there is shown a brace rail shield combination  6  for a rail  5  having a web  59 , a first flange  61  and a second flange  63  of a ladder  13  having at least one rung  4 . The brace rail shield combination  6  comprises a first portion  56  that has a shape that conforms with an interior cross sectional surface  60  of the rail  5  and an exterior surface  65  of the rail  5 . The brace rail shield combination  6  comprises 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. 
     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  FIG. 1 , is a plastic part  2  (which is formed from the first portion  56  and the second portion  58 ) with a metal plate  3 . The plastic part  2  includes a knee brace (second portion  58 ) and cover (first portion  56 ) to protect the fiberglass rail  5 . The brace rail shield combination  6  is used on extension ladders  13  of various heights. The one piece plastic part  2  with plate  3  forms a tight fit on the bottom end of the stationary (base) section of the extension ladder  13 , with the rail  5  fitting into the slot  33  of the brace rail shield combination  6 . The slot  33  has a cross-sectional shape of essentially a C, the first portion  56  having an outer side  67  that has an inner surface  69  which is essentially flat and conforms with and contacts the rail web&#39;s  59  outer surface and the first flange&#39;s  61  outer surface and the second flange&#39;s  63  outer surface and at least one hole  71 , and an inner side  73  that has an inner surface  75  which is essentially flat and conforms with and contacts the rail web&#39;s inner surface and has at least one hole  77  which aligns with the one hole  71  of the outer side  67 , the metal plate  3  having at least one hole  79  which aligns with the one hole of the inner side  73  and the outer side  67 , the rivet  7  extending through the one hole of the outer side and the inner side and the metal plate and the rail web  59  to fix the first portion  56  to the rail  5 . As shown in the embodiment of  FIG. 1   a , there is a first flange portion  81  attached to and extending from the outer side and the inner side and defining an opening  83  that has an essentially cross-sectional rectangular shape that conforms with the first flange&#39;s cross-section and which contacts the first flange&#39;s outer surface and inner surface, and a second flange portion  85  attached to and extending from the outer side and the inner side and defining an opening  87  that has an essentially cross-sectional rectangular shape that conforms with the second flange&#39;s cross-section and which contacts the second flange&#39;s outer surface and inner surface. 
     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 .  FIG. 6  shows the brace rail shield combination  6 , attached to the bottom of extension ladder  13 . The elimination of the heavy aluminum rail shield  17  lightens the ladder  13  and allows for easy aesthetic changes via the molding of the plastic part  2 . 
     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. 
       FIG. 1  shows the plastic part  2  assembled with the metal backup plate  3 , to complete the brace rail shield combination  6 . An alternate design of the brace rail shield combination  6 , allows multiple rail  5  profiles to be used. The metal backup plate  3  is pre-assembled by the injection molder to speed up the assembly process. The back up plate  3  consists of four holes used for riveting the brace rail shield combination  6  to the base rail  5 , and one larger hole for the shoulder bolt  11  to assemble the safety shoe  8 . 
       FIG. 2  shows the  6  on the bottom of the base section  5  of a FRP extension ladder  13 . The four semi-tubular rivets  7  are placed through the brace rail shield combination  6  and base FRP side rail  5  with the rivet&#39;s heads on the side opposite of the backup plate  3 . The two pop rivets  10  are then set, with washers  14  through the top of the brace rail shield combination  6  and into the bottom rung  4 . 
       FIG. 3  shows the assembled backup plate  3 , plastic part  2 , and safety shoe  8  riveted on to the base section  12  of the FRP extension ladder  13 . The safety shoe  8  can either be assembled prior to or during final assembly of the extension ladder  13 . 
     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.