Patent Publication Number: US-2016222729-A1

Title: Stepladder Having Tipping Prevention Function

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a ladder and, more particularly, to a stepladder. 
     2. Description of the Related Art 
     A conventional stepladder comprises two frames pivotally connected with each other at upper ends thereof, and two opposite linkages pivotally connected between the two frames to fix the two frames so as to prevent the angle between the two frames from being changed when in use. However, the lower end of each of the two frames is not supported solidly and stably, so that the two frames easily tip or fall down when the user is disposed at an inclined situation or when the two frames are placed on an uneven ground. In addition, the stepladder is not provided with any upright support structure so that the user cannot stand and work on the top of the stepladder. Further, the stepladder is not provided with any hanger for hanging the user&#39;s tool bag, thereby causing inconvenience to the user. 
     BRIEF SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a stepladder having a tipping prevention function. 
     In accordance with the present invention, there is provided a stepladder comprising two frames pivotally connected with each other, two pairs of support levers pivotally connected with the two frames, and two pairs of links pivotally connected with the two frames and pivotally connected with the support levers. 
     The stepladder further comprises two pairs of positioning members connected with the links. Each of the two frames is formed with a plurality of fixing holes. Each of the links has a first end pivotally connected with a mediate portion of each of the support levers. Each of the positioning members extends through a second end of each of the links and is positioned in one of the fixing holes of each of the two frames, so that each of the links is connected with each of the two frames. 
     Each of the two frames is provided with a side bar which has a first end formed with a connecting portion and a second end formed with a working portion. 
     The working portion of the side bar is provided with a hook. 
     Each of the two frames is provided with an upper retaining seat for holding the side bar and a lower retaining seat for holding the side bar. 
     Each of the support levers is pivotally connected between each of the two frames and each of the links. Each of the two frames is formed with two elongate slots. Each of the support levers has a first end pivotally connected with each of the links and a second end pivotally and movably mounted in one of the two elongate slots of each of the two frames. Each of the links has an upper end pivotally connected with each of the two frames and a lower end provided with a threaded rod which is connected with a threaded stand. 
     Each of the two frames is formed with a slideway to allow a sliding motion of the connecting portion of the side bar. The slideway of each of the two frames has two ends each formed with a limit hole to limit the connecting portion of the side bar. Thus, the working portion of the side bar is constantly directed upward and protrudes outward from the top of the stepladder. 
     Each of the two frames is provided with at least one foot board which has an interior provided with two extension brackets. Each of the extension brackets has a substantially L-shaped structure and has a transverse section extending into the interior of the foot board of each of the two frames and an upright section provided with a threaded rod which is connected with a threaded leg. 
     Each of the support levers has a substantially L-shaped profile and is located at a lower end of each of the two frames. 
     According to the primary advantage of the present invention, each of the support levers is expanded and placed on the ground, and each of the links is connected between each of the support levers and each of the two frames in an inclined manner, so that the two frames are supported solidly and stably so as to enhance solidity and stability of the stepladder and to prevent the stepladder from tipping or falling down, thereby protecting the user&#39;s safety. 
     According to another advantage of the present invention, the side bar is expanded to protrude upward from each of the two frames, so that the user can hold the side bar when standing on the two frames, thereby enhancing the user&#39;s safety. 
     According to a further advantage of the present invention, the side bar is provided with a hook to hang the user&#39;s tool bag when the user stands highly on the two frames. 
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1  is a perspective view of a stepladder in accordance with the preferred embodiment of the present invention. 
         FIG. 2  is a schematic operational view of the stepladder as shown in  FIG. 1 . 
         FIG. 3  is a side view of the stepladder as shown in  FIG. 1 . 
         FIG. 4  is a schematic operational view of the stepladder as shown in  FIG. 3 . 
         FIG. 5  is a schematic operational view of the stepladder as shown in  FIG. 4 . 
         FIG. 6  is a side view of a stepladder in accordance with another preferred embodiment of the present invention. 
         FIG. 7  is a schematic operational view of the stepladder as shown in  FIG. 6 . 
         FIG. 8  is a perspective view of a stepladder in accordance with another preferred embodiment of the present invention. 
         FIG. 9  is a schematic operational view of the stepladder as shown in  FIG. 8 . 
         FIG. 10  is a partially side cross-sectional view of a stepladder in accordance with another preferred embodiment of the present invention. 
         FIG. 11  is a schematic operational view of the stepladder as shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and initially to  FIGS. 1-3 , a stepladder in accordance with the preferred embodiment of the present invention comprises two frames “A” and “B” pivotally connected with each other, two pairs of support levers  11  pivotally connected with the two frames “A” and “B”, two pairs of links  13  pivotally connected with the two frames “A” and “B” and pivotally connected with the support levers  11 , and two pairs of positioning members  14  connected with the links  13 . 
     Each of the two frames “A” and “B” is formed with a plurality of fixing holes  12  which are equally distant from each other. Each of the two frames “A” and “B” is provided with a side bar  15  which has a first end formed with a connecting portion  151  and a second end formed with a working portion  152 . The working portion  152  of the side bar  15  is provided with a hook  153 . Each of the two frames “A” and “B” is provided with an upper retaining seat  154  for holding the side bar  15  and a lower retaining seat  155  for holding the side bar  15 . 
     Each of the support levers  11  has a substantially L-shaped profile and is located at a lower end of each of the two frames “A” and “B”. 
     Each of the links  13  has a first end  131  pivotally connected with a mediate portion of each of the support levers  11 . 
     Each of the positioning members  14  extends through a second end  132  of each of the links  13  and is positioned in one of the fixing holes  12  of each of the two frames “A” and “B”, so that each of the links  13  is connected with each of the two frames “A” and “B”. 
     As shown in  FIGS. 1 and 3 , when the two frames “A” and “B” are expanded outward to form a substantially A-shaped structure, each of the support levers  11  is pivoted outward and downward to abut the ground, and each of the links  13  is connected between each of the support levers  11  and each of the two frames “A” and “B” in an inclined manner. Thus, each of the support levers  11  and each of the links  13  construct a tipping prevention device  1  to enhance solidity and stability of the stepladder and to prevent the stepladder from tipping or falling down, thereby protecting the worker&#39;s safety. 
     As shown in  FIG. 2 , when the side bar  15  protrudes upward from each of the two frames “A” and “B”, the side bar  15  is positioned by the upper retaining seat  154 . 
     As shown in  FIG. 1 , when the side bar  15  is folded on each of the two frames “A” and “B”, the side bar  15  is positioned by the lower retaining seat  155 . 
     As shown in  FIG. 4 , each of the positioning members  14  is adjustably positioned in one of the fixing holes  12  of each of the two frames “A” and “B” to adjust the angle between each of the support levers  11  and each of the two frames “A” and “B”, so that the stepladder is placed on a slope zone solidly and stably, thereby protecting the worker&#39;s safety. 
     As shown in  FIG. 5 , each of the support levers  11  and each of the links  13  are folded on each of the two frames “A” and “B”. 
     Referring to  FIGS. 6 and 7 , each of the support levers  11  is pivotally connected between each of the two frames “A” and “B” and each of the links  13 . Each of the two frames “A” and “B” is formed with two elongate slots  10 . Each of the support levers  11  has a first end pivotally connected with each of the links  13  and a second end pivotally and movably mounted in one of the two elongate slots  10  of each of the two frames “A” and “B”. Each of the links  13  has an upper end pivotally connected with each of the two frames “A” and “B” and a lower end provided with a threaded rod  130  which is connected with a threaded stand  133 . In folding of each of the links  13 , the threaded stand  133  is rotated and moved relative to the threaded rod  130  to shorten the distance between the threaded stand  133  and each of the links  13 . Then, the second end of each of the support levers  11  is moved downward in one of the two elongate slots  10  of each of the two frames “A” and “B” as shown in  FIG. 7 , so that each of the links  13  is pivoted and moved toward each of the two frames “A” and “B” until each of the links  13  is folded on each of the two frames “A” and “B”. 
     Referring to  FIGS. 8 and 9 , each of the two frames “A” and “B” is formed with a slideway  150  to allow a sliding motion of the connecting portion  151  of the side bar  15 . The slideway  150  of each of the two frames “A” and “B” has two ends each formed with a limit hole  156  to limit the connecting portion  151  of the side bar  15 . Thus, the working portion  152  of the side bar  15  is constantly directed upward and protrudes outward from the top of the stepladder. 
     Referring to  FIGS. 10 and 11 , each of the two frames “A” and “B” is provided with at least one foot board “C” which has an interior provided with two extension brackets  16  and  16 ′. Each of the extension brackets  16  and  16 ′ has a substantially L-shaped structure and has a transverse section extending into the interior of the foot board “C” of each of the two frames “A” and “B” and an upright section provided with a threaded rod  162  which is connected with a threaded leg  161 . Thus, when the transverse section of each of the extension brackets  16  and  16 ′ is retracted into the interior of the foot board “C” of each of the two frames “A” and “B”, the upright section of each of the extension brackets  16  and  16 ′ and the threaded leg  161  are moved to abut each of the two frames “A” and “B” as shown in  FIG. 10 , and when the transverse section of each of the extension brackets  16  and  16 ′ is expanded outward from the foot board “C” of each of the two frames “A” and “B”, the upright section of each of the extension brackets  16  and  16 ′ and the threaded leg  161  are moved outward to space from each of the two frames “A” and “B” as shown in  FIG. 11  so as to provide a support function to each of the two frames “A” and “B”. 
     Accordingly, each of the support levers  11  is expanded and placed on the ground, and each of the links  13  is connected between each of the support levers  11  and each of the two frames “A” and “B” in an inclined manner, so that the two frames “A” and “B” are supported solidly and stably so as to enhance solidity and stability of the stepladder and to prevent the stepladder from tipping or falling down, thereby protecting the user&#39;s safety. In addition, the side bar  15  is expanded to protrude upward from each of the two frames “A” and “B”, so that the user can hold the side bar  15  when standing on the two frames “A” and “B”, thereby enhancing the user&#39;s safety. Further, the side bar  15  is provided with a hook  153  to hang the user&#39;s tool bag when the user stands highly on the two frames “A” and “B”. 
     Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.