Abstract:
A stepladder which is placed on a tool carrier and which is folded up when in the transport position with the handle extracted, has a folding step which in this position is flush with the side wall of the ladder part. The stepladder surrounds the tool carrier above the level of a base.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a step ladder comprising a tool carrier. The tool carrier serves to accommodate and carry tools, which step ladder is adapted for increasing the working height, e.g. on a building site, in a workshop, or in an assembly hall, but also in private households. 
       PRIOR ART 
       [0002]    A tool box comprising a stool is disclosed in DE 296 09 524 U1, in which the stool is lowered over a drawer cabinet, by which means the drawers are held in a closed position. 
         [0003]    A step ladder in the form of a stable, hollow box is disclosed in DE 2 127 666 A1, in which the top step forms a lid for a container situated beneath it. 
         [0004]    A multi-purpose step ladder is disclosed in DE 81 33 640 U1, in which tool bags can be attached inside the tubular frame of said ladder. 
         [0005]    It is an object of the present invention to further develop a step ladder in such a way that the tool carrier is fully closed when the step ladder has been fitted thereon such that accidental opening of the step ladder is prevented and that a collapsible step ladder is provided that is sufficiently stable to fulfill the requirements of official authorities or the standards for step ladders in general. 
       DESCRIPTION OF THE INVENTION 
       [0006]    The step ladder of the invention comprising a tool carrier consists of two ladder parts comprising a top step, the two ladder parts being foldably connected by means of a hinge in the region of the top step. 
         [0007]    At least one ladder part comprises a folding step pivotally disposed about a bearing between lateral uprights of the ladder part, said folding step being movable in the direction of the uprights of the ladder part when the step ladder is in a collapsed position, and to a position extending toward the other ladder part parallel to the top step when the step ladder is in an opened position. The tool carrier comprises a base and at least one tool carrier wall that is disposed thereon and extends away from the base and is adapted to be enclosed by the ladder parts. The tool carrier wall comprises a guide surface and/or a guide point for the folding step, disposed on a side facing away from the base, which guide surface and/or guide point interacts with the folding step and guides the folding step from the opened position parallel to the top step to the position in the direction of the uprights when the ladder part comprising the folding step is lowered onto the tool carrier from above. A hinged strut possessing high compressive and tensile rigidity is provided on the folding step at a distance from the bearing, is rotatably joined to the opposing ladder part, and has a length and bearing points that are dimensioned such that the ladder parts can be moved from the opened position to the collapsed position and vice versa when the folding step is being pivoted. 
         [0008]    Therefore, in the collapsed position, a tool box is created consisting of the step ladder and the tool carrier, for ease of transport. In the opened position, the step ladder and the tool carrier represent two separate pieces of equipment that can be used individually. Since the ladder parts collapse automatically and the folding steps fold down when being mounted onto the tool carrier, all openings are covered and the tool box is closed to the environment. 
         [0009]    It is advantageous when each ladder part comprises a single step. In this case it is possible to ascend the step ladder on either side and a safety bar is not required, as may be the case with single-sided ladders. 
         [0010]    It is advantageous when the tool carrier wall is eccentrically disposed on the base by means of the guide surface and/or guide point, and when an inner wall comprises a more centrally disposed inner guide surface or inner guide point. The inner guide surface or inner guide point may be disposed above the guide surface or the guide point of the tool carrier wall. Thus subdivision of the path of movement is possible, and the different positions of the ladder parts relatively to each other can be accommodated in a simple manner. 
         [0011]    It is advantageous when the guide surface of the tool carrier wall is at an angle of from 35 to 60 degrees, preferably 45 degrees, and when the guide surface of the inner wall is at an angle of from 10 to 30 degrees, preferably from 15 to 20 degrees. For practical purposes, within said range of angles the geometric ratios are sufficiently well accounted for the purpose of effecting secure closing. 
         [0012]    It is advantageous when the ladder part comprises a closed wall section below the folding step and the side wall of the ladder part is completely closed when in the collapsed position. 
         [0013]    It is advantageous when the tool carrier has a handle on the side facing away from the base, which handle is guided longitudinally displaceably along a sliding rail on the inner wall and/or on the tool carrier wall and is transversely tiltable relatively to the sliding rail in an upper position. As a result, the tool carrier is able to hold tools in its central region. 
         [0014]    It is advantageous when the step ladder has a recess for the handle in the top step in the region of the hinge, the handle being guarded against tilting by means of contact surfaces on the top step when the step ladder is mounted. This facilitates transportation and handling of the tool box. 
         [0015]    It is advantageous when the handle is entirely retractable when the step ladder is mounted, resulting in it being flush with the surface of the step. The space required to store the tool box is thus minimized. 
         [0016]    It is advantageous when the base has a groove for the purpose of receiving and laterally retaining the ladder part on at least two opposing edges by means of a bottom wall section entering the groove. This prevents spreading of the ladder parts when the ladder is mounted. 
         [0017]    It is advantageous when the ladder part comprising the folding step comprises a support on the inner side of the upright on which the folding step rests in the opened position. Stabilization is thereby achieved and the opening angle further restricted. 
         [0018]    It is advantageous when the strut on the ladder parts is in each case attached below the bearing of the folding step so that, when the step ladder is in an opened position, the strut assumes an angle of from 5 to 45 degrees, preferably from 15 to 20 degrees. Such an arrangement of the strut facilitates smooth opening and closing of the ladder during everyday use. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The invention is explained below with reference to the drawings, in which: 
           [0020]      FIG. 1  shows a step ladder  1  for mounting on a tool carrier in an upper position; 
           [0021]      FIG. 2  shows the step ladder of  FIG. 1  lowered over the tool carrier  2  to assume a lower position; 
           [0022]      FIG. 3  shows the step ladder of  FIGS. 1 and 2  with the ladder parts fully closed; 
           [0023]      FIG. 4  shows the tool carrier as viewed from above; 
           [0024]      FIG. 5  is a side view of the tool carrier; 
           [0025]      FIG. 6  illustrates the forced coupling of the ladder parts and the folding steps; 
           [0026]      FIG. 7  is a diagrammatic view of the collapsed step ladder; 
           [0027]      FIG. 8  shows supports for varying and supporting the opened folding steps; 
           [0028]      FIG. 9  shows the ladder part comprising the step and the folding step resting on a support; 
           [0029]      FIG. 10  shows a handle mounted on the inner wall in a first, rotated position; 
           [0030]      FIG. 11  shows the handle of  FIG. 10  in a partly recessed, second position; 
           [0031]      FIG. 12  is a perspective view of the folded step ladder mounted on the tool carrier. 
       
    
    
     EXEMPLARY EMBODIMENT 
       [0032]      FIG. 1  shows a step ladder  1  for mounting on a tool carrier  2 , said step ladder comprising two ladder parts  3 ,  4  each comprising a top step  5 ,  6 , which two ladder parts are interconnected by means of a hinge  7  and are adapted to close toward, or open away from, each other. Each ladder part  3 ,  4  comprises a folding step  11 ,  12  pivotally disposed about a bearing  10  between the lateral rails  8 ,  9  of the ladder parts  3 ,  4 , said folding step being in the opened position of the step ladder  1  as shown, parallel to the top step  5 ,  6  and thus extending toward the other ladder part  3 ,  4 . 
         [0033]    The step ladder  1  is symmetrically constructed about a central axis  13 , the hinge  7  being disposed on said central axis  13 . The tool carrier  2  comprises a base  21  and a tool carrier wall  22  disposed on, and extending away from, said base  21 , said tool carrier wall being laterally enclosed by the ladder parts  3 ,  4  when the ladder is mounted as illustrated in  FIG. 3  and described below with reference thereto. 
         [0034]    The tool carrier wall  22  is eccentrically disposed on the base  21 , that is to say, at a distance from the central axis  13 , and an inner wall  23  is provided at a shorter distance from the central axis  13 . The inner wall  23  comprises a guide surface  24 ,  25  on its upper side facing away from the base  2 , which guide surface slopes outwardly, that is to say, away from the central axis  13 , and is adapted to interact with the folding step  11 ,  12  when the opened step ladder is mounted on the tool carrier  2  from above. 
         [0035]    Instead of the outwardly and downwardly sloping guide surface  24 ,  25 , a guide point or support point may be used, upon which the folding step  11 ,  12  initially rests when the step ladder  1  is mounted and along which it glides when the step ladder  1  is lowered. However, the use of a guide surface  24 ,  25  has the advantage over a guide point (not shown) that a defined support having a larger flat surface may be created, at least for a single, intermediate position. However, this is not absolutely necessary. 
         [0036]    In the upper position of the step ladder  1  in relation to the tool carrier  2 , as shown in  FIG. 1 , the folding steps  11 ,  12  still rest against the guide surfaces  24 ,  25  of the inner wall  23 , and the step ladder is still shown in a maximally opened position, the angle shown at this point being 15 degrees per ladder part, that is to say, 30 degrees in all. 
         [0037]    The direction of movement of the step ladder  1  and the tool carrier  2  in relation to each other is indicated by the arrow  26  oriented along the central axis  13 . 
         [0038]    In addition to the guide surfaces  24 ,  25  on the inner wall  23 , the tool carrier wall  22  also comprises a guide surface  31  disposed below the guide surface  24  of the inner wall  23 , that is to say, closer to the base  21  and at a more outward position. The guide surface  31  is at a more acute angle than the guide surface  24 , but also slopes outwardly and downwardly. The function of the guide surface  31  on the tool carrier wall  22  is explained below in detail with reference to the figures. 
         [0039]      FIG. 1  further shows a circular recess  41  communicating with an elongated sliding rail  43  formed by a further recess  42 . Said recesses  41 ,  42  serve to accommodate a handle (not shown) and to enable tilting thereof to an upper position and to enable the insertion and fixation of the handle to prevent it from tilting in the region of the sliding rail  43 . 
         [0040]    The base  21  has a locating slot  51  disposed near its outer edge  52 . Said slot serves to receive and secure the ladder part  3  when the closed step ladder  1  is totally fitted over the tool carrier  2 . 
         [0041]      FIG. 2  shows how the step ladder  1  is further lowered toward the base  21  in the direction of the arrow  26 , in order to be fitted over the tool carrier  2 . To this end, the folding steps  11 ,  12  have been guided entirely past the guide surfaces  24 ,  25  to rest on the guide surface  31  of the tool carrier wall  22 . The two ladder parts  3 ,  4  have moved toward one another and the opening angle of the step ladder  1  has decreased due to a forced coupling of the two ladder parts  3 ,  4  with the folding step  11 ,  12  (shown and explained below with reference to  FIG. 6 ), that is to say, the step ladder has incipiently closed around the central axis  13 . In this position, the steps  5 ,  6  have also approached one another around the joint  7 . 
         [0042]      FIG. 3  shows the step ladder  1  in the fully collapsed position of the ladder parts  3 ,  4  prior to reaching the final position, complete closure being effected by further lowering of the unit toward the base  21 . The folding steps  11 ,  12  have been fully raised, at least approximately, by sliding along the guide surface  31  and thus lie in the plane of the outer surfaces of the ladder parts  3 ,  4 . The lower edge of the ladder parts  3 ,  4  is close to being docked in the locating slot  51  disposed at the outer edge  52  of the base  21 . When the closed step ladder  1  is completely fitted over the tool carrier  2 , the ladder parts  3 ,  4  are accommodated and secured in said slot  51 . For the purpose of facilitating the docking action, outward protrusions  53  are formed on the tool carrier wall  22  that act as glide slopes and guide the lower edge of the ladder parts  3 ,  4  prior to their reaching the final position. 
         [0043]      FIG. 4  shows the tool carrier  2  as viewed from above and illustrates the base  21  comprising the edge  51  and the groove  52  contained therein, the edge  51  being only required on two oppositely disposed sides of the base. The tool carrier wall  22  is disposed on the base  21  in a central region around the central axis (not shown), allowing a view of the guide surface  31 . Such a tool carrier wall  22  is basically sufficient, but two oppositely disposed tool carrier walls are provided for the purpose of increasing the storage capacity to allow for the tidy storage of tools. The inner wall  23  is disposed between the two tool carrier walls, the guide surfaces  24 ,  25  being located on the upper surface of the inner wall, facing the viewer. 
         [0044]      FIG. 5  shows the tool carrier  2  in a side view not including the step ladder nor the inner surfaces. The guide surfaces  31  disposed on each of the oppositely disposed tool carrier walls  22  on either side of the central axis  13  are shown, as is the base  21  having the edge  52  and the groove  51  contained therein. This embodiment is sufficient to enable raising of the folding steps  30  when the step ladder is being mounted. 
         [0045]      FIG. 6  illustrates the forced coupling of the ladder parts  3 ,  4  and the folding steps  11 ,  12 . A hinged strut  61 ,  62  possessing high compressive and tensile rigidity is provided on each of the folding steps  11 ,  12  at a distance from the bearing  10 , rotatably joined to the oppositely disposed ladder parts  4 ,  3 , the length  1  of which and the bearing points  63 ,  64  in the ladder part  3 ,  4  being dimensioned such that the ladder parts  3 ,  4  can be moved from the opened position to the collapsed position, and vice versa, by swiveling the folding step  11 ,  12 . 
         [0046]    The distance of the bearing of the folding step  11 ,  12  from the hinge  7  connecting the two ladder parts  3 ,  4  is identified as radius R. The strut  61 ,  62  is fixed to the bearing points  65 ,  66  in the folding steps  11 ,  12 . If one of the folding steps  11 ,  12  is moved about the hinge  10  from the opened position (as shown) of the step ladder to the position identified by dashed lines, indicated as  11 ′,  12 ′ (shown in  FIG. 7  below), the process of raising the folding step  11 ,  12  enables a pulling force to be applied to the strut, causing the opposing ladder part to move toward the ladder part accommodating the folding step, thus closing the step ladder. 
         [0047]      FIG. 7  is a diagrammatic view of the closed step ladder, the struts  61 ,  62  being attached inside the step ladder and thus concealing the mechanism and preventing external interference. In the collapsed position shown below, the struts  61 ,  62  further ensure that the folding steps  11 ,  12  are approximately flush with the surface of the ladder parts  3 ,  4  and that they are also braced against external pressure. The present embodiment also shows that supports  67 ,  68  are provided on the inner surfaces of the ladder rails  8 ,  9  of the ladder parts  3 ,  4 , supporting the opened folding steps  11 ,  12 , shown in detail in  FIG. 8 , the struts not being shown for the sake of clarity. 
         [0048]      FIG. 9  shows the ladder part  4  comprising the step  6  and the folding step  12  resting on the support  68 , that is to say, with the ladder being in an opened position. 
         [0049]      FIGS. 10 and 11  show the manner in which a handle  71  can be mounted on the inner wall  23  for the purpose of making it rotatable and retractable.  FIG. 10  shows the handle  71  in an extended position and tilted sideways relatively to the central axis  13 . Set in said position is an extension tongue  73  supporting the actual hand piece  72  comprising a lug  74  in the region of the circular recess  41  having a diameter such that the lug  74  may be accommodated in its entire length. The lug  74  comprises guide surfaces  75  interacting with the elongated sliding rail  43  comprising the further recess  42  in a position not shown. 
         [0050]    Said position is shown in  FIG. 11 , the handle  71  comprising the hand piece  72  and the extension tongue  73  slightly protruding beyond the steps  5 ,  6  after the step ladder  1  has been mounted, that is to say, to such an extent that an opening  76  is still accessible into which a lock (not shown) can be set for the purpose of locking the mounted step ladder against removal of the tool carrier, the inner wall  23  of which is shown. Although the recess  41  with fully extended handle  71  cannot itself prevent tilting of the handle, the handle  71  together with contact areas  77 ,  78  mounted on the steps  5 ,  6  is stabilized in the region of an opening  79  of the hinge. In the partly inserted position shown, the hand piece  71  is further secured against tilting in the region of the sliding rail  43  in the recess  42  by means of the guiding cam  74 , even when the step ladder  1  is not mounted. 
         [0051]    The handle  71  can be wholly countersunk in the tool box formed by the step ladder mounted on the tool carrier, with the result that the upper surface of the hand piece  72  is flush with the steps  5 ,  6 . 
         [0052]      FIG. 12  is a perspective view of the collapsed step ladder  1  mounted on the tool carrier  2  and ready for transportation, the handle  71  being extended. In this position, the folding step  12  is flush with the side wall of the ladder part  4  comprising a closed wall section  81 , the two ladder rails  8 ,  9  being of such widths that they are in contact with each other. The step ladder  1  thus completely encloses the tool carrier  2  above the base  21 . 
         [0053]    The lowest wall section  82  is partly sunk into the base  2  or, more specifically, is engaged thereby, thus safeguarding said wall section from spreading. 
         [0054]    If the tool carrier and the step ladder are being used independently of each other, they can be inter-adjusted for the purpose of achieving an ergonomic working height for the removal of tools from the tool carrier. For the purpose of stabilizing such adjustment, the underside of the tool carrier base may comprise a connecting element allowing for a positive connection with an appropriately designed connecting element on the upper surface of the step ladder, for example a tongue and groove connection in the form of ribs and protrusions.