Patent Publication Number: US-6902035-B2

Title: Step stool with step lock

Description:
BACKGROUND 
   The present disclosure relates to step stools. More particularly, the present disclosure relates to step stools that have a step lock. 
   Step stools have a frame and one or more steps. The steps may be used by individuals for elevation when reaching for objects, painting walls, or any everyday task where extra elevation would be helpful. 
   SUMMARY 
   According to the present disclosure, a step stool includes a frame and a step coupled to the frame for pivotable movement. A step lock is used to block pivotable movement of the step relative to the frame. 
   In an embodiment of the step stool, the frame is foldable between folded and unfolded positions. The step lock includes a latch able to pivot between a latch position and a release position. In the latch position, the latch is arranged to latch to a strut of the frame to block pivotable movement of the step to maintain the frame in its unfolded position. In the release position, the latch is arranged to release the strut to allow pivotable movement of the step so that the step stool can be folded. 
   The step includes a platform to support a person thereon. A notch member is included in a periphery of the platform and formed to include a notch. The latch is arranged for pivotable movement in the notch. A pivot limiter is mounted to the notch member and arranged to engage the latch when the latch assumes the release position to limit pivotable movement of the latch in the notch away from the latch position. Limiting pivotable movement of the latch facilitates pivotable movement of the step and, in turn, facilitates folding of the frame. 
   Additional features of the apparatus will become apparent to those skilled in the art upon consideration of the following detailed description exemplifying the best mode of the disclosure as presently perceived. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The detailed description particularly refers to the accompanying figures in which: 
       FIG. 1  is a perspective view of a step stool showing the step stool including a foldable frame, a pivotable step mounted to the frame, and a step lock including a latch arranged in a latch position in a notch formed in a periphery of a platform of the step to lock the step in place to maintain the frame in an unfolded position; 
       FIG. 2  is a perspective view showing the latch pivoted to a release position for engagement with a pivot limiter shown in  FIGS. 4 ,  6 , and  7  to facilitate pivotable movement of the step to fold the frame; 
       FIG. 3  is a side elevation view showing the step stool folded; 
       FIG. 4  is an exploded perspective view showing the pivot limiter arranged, for example, as a plate mounted to a notch member formed to include the notch in the periphery of the platform; 
       FIG. 5  is a perspective view showing the latch including an inclined, generally U-shaped limiter engagement surface (on the right) that is used to mate against the pivot limiter when the latch assumes the release position; 
       FIG. 6  is a sectional view taken along lines  6 — 6  of  FIG. 1  showing the latch positioned in its latch position by a latch pivoter in the form of, for example, a spring mounted between the pivot limiter and the latch; and 
       FIG. 7  is a sectional view taken along lines  7 — 7  of  FIG. 2  showing engagement between the limiter engagement surface of the latch and a latch engagement surface of the pivot limiter to facilitate pivotable movement of the step and folding of the frame. 
   

   DETAILED DESCRIPTION 
   A step stool  10  shown in  FIGS. 1–3  includes a foldable frame  12 , a step  14  mounted to frame  12  for pivotable movement, and a step lock  16 . Frame  12  is arranged to move between an unfolded position shown in  FIG. 1  and a folded position shown in  FIG. 3 . Step lock  16  includes a latch  18  mounted for pivotable movement in a notch  20  formed in a periphery  22  of a platform  24  included in step  14  between a latch position shown in  FIGS. 1 and 6  and a release position shown in  FIGS. 2 and 7 . In the latch position, latch  18  is arranged to latch to frame  12  to block pivotable movement of step  14  to maintain frame  12  in its unfolded position. In the release position, latch  18  is arranged to release frame  12  to allow pivotable movement of step  14  to move frame  12  to its folded position. 
   Step  14  includes a pivot limiter  26  shown in  FIGS. 4 ,  6 , and  7 . Pivot limiter  26  is arranged to engage latch  18  when latch  18  assumes the release position to limit pivotable movement of latch  18  in notch  20  away from the latch position to facilitate pivotable movement of step  14  relative to frame  12  to move frame  12  from the unfolded position to the folded position upon application of a folding force to latch  18 . Pivot limiter  26  thus provides pivot limiter means for engaging latch  18  when latch  18  assumes the release position to limit pivotable movement of latch  18  in notch  20  away from the latch position to facilitate pivotable movement of step  14  relative to frame  12  to move frame  12  from the unfolded position to the folded position upon application of a folding force to latch  18 . 
   Frame  12  includes a front leg unit  28  and a rear leg unit  30 , as shown in  FIGS. 1–3 . Front and rear leg units  28 ,  30  are coupled to one another for pivotable movement between the folded and unfolded positions. Front leg unit  28  includes a pair of legs  32  and rear leg unit  30  includes a pair legs  34 . Legs  32  and legs  34  coupled to one another by leg pivots  36  for pivotable movement of front and rear leg units  28 ,  30 . 
   Platform  24  of step  14  is mounted to front leg unit  28  for pivotable movement relative thereto, as shown in  FIGS. 1 ,  2 , and  4 . Platform pivots  38  shown in  FIG. 4  are mounted to front legs  32  and establish a platform pivot axis  40  about which the platform  24  pivots upon movement of the front and rear leg units  28 ,  30  between the folded and unfolded positions. 
   A platform pivoter  42  interconnects platform  24  and rear leg unit  30 , as shown in  FIGS. 1 ,  2 , and  4 . Platform pivoter  42  is arranged to pivot platform  24  relative to front leg unit  28  upon movement of units  28 ,  30  between the folded and unfolded positions. During movement of units  28 ,  30  from the folded position to the unfolded position, platform pivoter  42  pivots platform  24  so that notch members  45  included in opposite sides of platform  24  come to rest on a strut  44  mounted to rear legs  34  therebetween. In the illustrated embodiment, platform pivoter  42  includes a pair of links  47  and a pair of pivot mounts  49  for each link  47 . 
   Periphery  22  of platform  24  is formed to include notch  20 , as shown best in  FIG. 4 . A rear portion  46  of periphery  22  includes a notch member  48 . Notch member  48  is formed to include notch  20 . Notch member  48  includes an inner wall  50  and a pair of spaced-apart side walls  52  extending outwardly from inner wall  50 . 
   Pivot limiter  26  is mounted to notch member  48 , as shown in  FIGS. 4 ,  6 , and  7 . In the illustrated embodiment, pivot limiter  26  is a plate (which may be referred to as a pivot limiter plate) mounted to a bottom edge  62  of notch member  48  and mounted to inner wall  50  and side walls  52  so as to extend across notch  20 . It is within the scope of this disclosure for pivot limiter  26  to have other configurations. For example, pivot limiter  26  may be arranged as some other body (e.g., posts, blocks, walls) mounted to platform  24  in some other location (e.g., above bottom edge  62  on notch member  48 , below bottom edge  62  to underside of platform  24 ). 
   Step lock  16  includes a latch pivot axle  54  that extends through axle-receiving apertures  55  formed in latch  18 , as shown in  FIG. 4 . Latch pivot axle  54  is mounted to notch member side walls  52  and supports latch  18  for pivotable movement about a latch pivot axis  56  shown in  FIGS. 6 and 7  between the latch and release positions. Washers  58  and an axle retainer  60  shown in  FIG. 4  are used with axle  54  in mounting axle  54  to side walls  52 . It is within the scope of this disclosure to mount latch  18  for pivotable movement in a variety of other ways. 
   Latch  18  includes a handle  64 , a pair of couplers  66 , and a limiter engager  68 , as shown in  FIGS. 4–7 . Handle  64  is located along a latch outer portion  70  and is arranged to be gripped by the hand of a person to pivot latch  18  from the latch position to the release position as suggested in  FIGS. 2 and 7 . Each coupler  66  is located along a latch side portion  72  and is arranged to latch to strut  44  when frame  12  assumes the unfolded position and latch  18  assumes the latch position. Limiter engager  68  is located along latch side portions  72  and along a latch inner portion  74  in notch  20  and arranged to engage pivot limiter  26  when latch  18  assumes the release position. 
   Pivot limiter  26  and limiter engager  68  are arranged for engagement with one another. Pivot limiter  26  underlies limiter engager  68  and includes a latch engagement surface  76  shown in  FIGS. 4 ,  6 , and  7 . Limiter engager  68  includes a limiter engagement surface  78  shown in  FIGS. 5–7 . Limiter engagement surface  78  is inclined relative to the latch engagement surface  76  when latch  18  is positioned in the latch position, as shown in  FIG. 6 , and mates against latch engagement surface  76  when latch  18  is positioned in the release position, as shown in  FIG. 7 . In the illustrated embodiment, surfaces  76 ,  78  are generally planar. It is within the scope of the disclosure for surfaces  76 ,  78  to be non-planar. 
   Limiter engagement surface  78  is formed on a lower rim  80  of latch  18 , as suggested in  FIG. 5 . Side portions  82  of surface  78  extend along latch side portions  72  on rim  80  and an inner portion  84  of surface  78  extends along latch inner portion  74  on rim  80 . Rim  80  includes a coupler support web  86  to support a coupler  66  and each side portion  82  is formed on one of coupler support webs. Side portions  82  and inner portion  84  are arranged such that limiter engagement surface  78  is generally C-shaped. 
   Step lock  16  includes a latch pivoter  88 , as shown in  FIGS. 4 ,  6 , and  7 . Latch pivoter  88  is arranged to pivot latch  18  from the release position to the latch position. 
   In the illustrated embodiment, latch pivoter  88  is a coil spring mounted to pivot limiter  26  and latch  18 . A first pivoter retainer  90  mounted to pivot limiter is arranged to retain an end portion of spring  88  in place. First pivoter retainer  90  is, for example, a boss extending from latch engagement surface  76 . An opposite end portion of spring  88  is retained by a second pivoter retainer  92 . Second pivoter retainer  92  is, for example, a cylindrical recessed portion that is formed in latch  18  and receives the opposite end portion of spring  88 . Rim  80  partially surrounds second pivoter retainer  92 . It is within the scope of this disclosure for latch pivoter  88  to take other forms. For example, latch pivoter  88  may be a torsion spring and may be mounted in a different location such as next to one of latch side portions  72  within or outside of rim  80 . 
   An access inhibitor  94  shown in  FIGS. 4 ,  6 , and  7  is arranged to inhibit access to pivot limiter  26 . Access inhibitor  94  is positioned outwardly from pivot limiter  26  underneath latch  18 . In the illustrated embodiment, access inhibitor  94  is a wall extending along and upwardly from an outer portion  96  of pivot limiter  26 .