Note: Descriptions are shown in the official language in which they were submitted.
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STEP STOOL
Bac)~round and Summary of the Invention
The present invention relates to a step stool, and particularly, to a
foldable step stool having legs that fold between an opened use position and a
collapsed storage position. More particularly, the present invention relates
to a
foldable step stool including a step-folding linkage.
According to the present invention, a foldable step stool includes a
frame, first and second steps coupled to pivot on a front leg of the frame,
and a step
guide link. The step guide link is coupled to pivot on the first and second
steps and to
slide on a rear leg of the frame during movement of the rear leg relative to
the front leg
between an opened use position and a closed storage position.
In preferred embodiments, the step guide link is formed to include a
guide slot and the rear leg includes a guide pin arranged to slide in the
guide slot
during movement of the rear leg between the opened use position and the closed
storage position. One step guide link is provided on the left side of the
first and
second steps and another step guide link is provided on the right side of the
first and
second steps. Left and right guide pins included in the rear leg slide in
guide slots
formed in the left and right step guide links to control pivoting movement of
the first
and second steps relative to the front and rear legs during opening and
closing of the
foldable step stool.
Additional features of the invention will become apparent to those
skilled in the art upon consideration of the following detailed description of
preferred
embodiments exemplifying the best mode of carrying out the invention as
presently
perceived.
Brief Description of the Drawings
The detailed description particularly refers to the accompanying figures
3 0 in which:
Fig. 1 is a perspective view of a step stool in accordance with the
present invention showing front and rear legs of the step stool in an opened
use
position, a top step pivotably coupled to the front leg, a bottom step
rivotably coupled
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to the front leg beneath the top step, and a step guide link pivotably coupled
to the top
and bottom steps and slidably coupled to the rear leg to slide a shown, for
example, in
Figs. 2-4;
Fig. 2 is a side elevation view of the step stool of Fig. 1 showing the
step stool in the use position with the top and bottom steps in a
substantially horizontal
position, the step guide link being formed to include a guide slot, and the
rear leg
including a guide pin positioned at an upper end of the slot to ride therein;
Fig. 3 is a side elevation view of the step stool of Fig. 1, with portions
broken away, showing the step stool in a partly closed position with the top
and
bottom steps tilted and the guide pin of the rear leg positioned to lie
between the upper
and lower ends of the guide slot;
Fig. 4 is a side elevation view of the step stool of Fig. 1 showing the
step stool in a closed storage position with the top and bottom steps in a
substantially
vertical position and the guide pin of the rear leg positioned to lie at the
lower end of
the slot;
Fig. 5 is front view of the step stool of Fig. 1 showing the top and
bottom steps in the vertical storage position;
Fig. 6 is a side elevation view of the step stool of Fig. 1, with portions
broken away, showing the step stool in the use position and the guide pin of
the rear
leg positioned to lie in a notch positioned to communicate with an upper end
of the
guide slot;
Fig. 7 is a sectional view taken along line 7-7 of Fig. 6 showing the rear
leg pivotably coupled to the front leg;
Fig. 8 is a side elevation view of another embodiment of a step stool,
with portions broken away, showing the step stool having a top step formed to
include
a notch for receiving a guide pin of the rear leg when the step stool is in
the opened
use position; and
Fig. 9 is a sectional view taken along line 9-9 of Fig. 8 showing the
guide pin of the rear leg positioned to extend through a rear leg member, the
step
guide link, and a side wall of the top step to provide additional support for
the top step
when the step stool is in the opened use position.
Detailed Description of the Drawings
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As shown in Fig. 1, foldable step stool 10 includes a frame 12 having a
front leg 14 and a rear leg 16 pivotably coupled to front leg 14. Step stool
10 also
includes a top step 18 pivotably coupled to front leg 14, a bottom step 20
pivotably
coupled to front leg 14, and a step guide link 22 pivotably coupled to top and
bottom
steps 18, 20 and slidably coupled to rear leg 16. Rear leg 16 includes a rear
leg
member 46 and a guide pin 64 coupled to rear leg member 46 and arranged to
slide
back and forth in a guide slot 62 formed in step guide link 62 as rear leg 16
moves
between an opened use position at an angle to front leg 14 as shown, for
example, in
Figs. 1, 2, and 6 and a closed storage position alongside front leg 14 as
shown, for
example, in Figs. 4 and 5.
Frame 12 of step stool 10 is foldable between an opened use position,
shown in Fig. l, in which a bottom end 24 of front leg 14 is spaced apart from
a
bottom end 26 of rear leg 16 to form a Y-configuration and a collapsed storage
position, as shown in Fig. 4, in which front and rear legs 14, 16 are folded
together.
The overall length of step stool 10 in the storage position is no longer than
the overall
length in the use position to provide a compact unit. Frame 12 is converted
easily
between the use position and the storage position by pulling upwardly on a
rear end 28
of top step 18 and tilting step stool 10 to the left. In response to gravity,
rear leg 16
automatically pivots toward front leg 14 causing step stool 10 to assume the
collapsed
or closed storage position.
As shown in Fig. 1, front leg 14 of frame 12 includes opposite front leg
members 30, 32 each including a bottom end 24 and an opposite top end 34, end
caps
31 coupled to bottom ends 24 of front leg members 30, 32, and a handle portion
36
extending between leg members 30, 32. While front and rear legs 14, 16 of
frame 12
are preferably constructed of steel tubing, a wide variety of materials may be
used.
As shown in Fig. 1, top and bottom steps 18, 20 of frame 12 extend
between leg members 30, 32 spaced-apart from handle portion 36. Top step 18 is
positioned to lie spaced-apart from top end 34 of front leg 14 and bottom step
20 is
positioned to lie between top step 18 and bottom end 24 of front leg 14. Top
and
bottom steps 18, 20 include step surfaces 38 and support panels 40 extending
from
step surfaces 38 toward end 24.
Step stool 10 further includes a plurality of pivot pins 42 having a
cylindrical stepped portion 43 pivotably coupling top and bottom steps 18, 20
to front
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leg members 36, 38 so that step surfaces 38 of top and bottom steps 18, 20
tilt relative
to front leg 14 as frame 12 is moved between the use and storage positions.
Stepped
portions 43 are positioned to lie between top and bottom steps 18, 20 and
front leg
members 30, 32. Although the step stool 10, shown in Figs. 1-7, includes only
one
bottom step 20 beneath top step 18, it is within the scope of the disclosure
for
additional steps that are similar to bottom step 20 to be coupled to front leg
14 above
and/or below top step 18.
Referring now to Figs. 6 and 7, rear leg 16 of frame 12 is coupled to
front leg 14 by pivot pin 44. Rear leg 16 includes first and second rear leg
members
46, 48, a cross strut 50, and a pair of corner stabilizer feet 52 coupled to
cross strut
50. Cross strut 50 extends between rear leg members 46, 48. Upper ends 54 of
first
and second rear leg members 46, 48 are flattened to fit in slots 56 formed in
front leg
members 30, 32.
Step stool 10 further includes a plurality of pivot pins 58 having
cylindrical stepped portions 60 pivotably coupling top and bottom steps 18, 20
to step
guide link 22. Stepped portions 60 are positioned to lie between top and
bottom steps
18, 20 and rear leg members 46, 48 as shown, for example, in Fig. 5. Step
guide link
22 maintains a substantially parallel relation between top and bottom steps
18, 20
during movement of step stool 10 between the use and storage positions as
shown in
Figs.2-4.
Step guide link 22 is formed to include a guide slot 62 and rear leg 16
further includes a rear leg member 46 and a guide pin 64 positioned to slide
in guide
slot 62 during movement of step stool 10 between the use and storage
positions.
While in the use position, guide pin 64 is positioned to lie in an upper end
66 of guide
slot 62 as shown in Fig. 6. While in the storage position, guide pin 64 is
positioned to
lie in a lower end 68 of slot 62 as shown in Fig. 4. Upper end 66 of guide
slot 62 is
formed to communicate with a notch 70 formed in step guide link 22 and
provided
with a lower edge 72 positioned to "capture" guide pin 64 while step stool 10
is in the
opened use position.
Step guide link 22 further includes a tab 74 coupled to a lower end (link
member) 76 of step guide link 22 and a pin-receiving notch 78 formed in a
middle
portion 80 of link 22. Tab 74 is positioned to engage front leg 14 when step
stool 10
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is in the storage position. Pin-receiving notch 78 is positioned to receive
stepped
portion 43 coupling top step 18 to front leg 14 as suggested in Figs. 4 and 5.
To fold frame 12 of step stool 10 from the use position to the storage
position, the user grasps handle portion 36 and tilts step stool 10 to the
left and lifts up
on rear end 28 of top step 18 to pull guide pin 64 from notch 70. When guide
pin 64
is free of notch 70, gravity pulls bottom end 26 of rear leg 16 toward bottom
end 24 of
front leg 16 and guide pin 64 slides down through guide slot 62 as shown in
Fig. 3.
Guide pin 64 continues to travel down through guide slot 62 until engaging
lower end
68 of guide slot 62 with step stool 10 in the flattened storage position as
shown in
Fig. 4.
Pin-receiving notch 78 permits step stool 10 to be folded to a
substantially flat position by providing clearance between step guide link 22
and
stepped portion 43 of pivot pin 42 coupled to top step 18 as shown in Fig. 4.
Tab 74
is positioned to engage front leg 14 while step stool 10 is in the storage
position to
prevent step guide link 22 and bottom step 20 from traveling over center.
To expand step stool 10 from the storage position to the use position
23, the user pivots rear leg 16 on front leg 14. As shown by arrow 84 in Fig.
6, a user
steps on bottom step 20 to tilt bottom step 20 to the horizontal use position,
pull step
guide link 22 downwardly, and tilt top step 18 toward the horizontal use
position.
Because guide pin 64 of rear leg 16 is constrained to move in guide slot 62 of
step
guide link 22, bottom end 26 of rear leg 16 swings away from bottom end 24 of
front
leg 14. As the user continues to step on bottom step 20, bottom step 20 and
top step
18 continue to move toward the horizontal use position and rear leg 16
continues to
swing out from front leg 14 until guide pin 64 engages upper end 66 of guide
slot 62
to place step stool 10 in the use position as shown in Figs. 1, 2, and 6.
Guide pin 64 of
rear leg 16 then becomes lodged in notch 70 so that lower edge 72 of guide
slot 62
prevents downward movement of guide pin 64 in guide slot 62 until a user
desires to
move step stool 10 to the storage position.
Thus, step stool 10 provides a support structure that folds to a
substantially flat position with limited components. Furthermore, notch 70
communicating with guide slot 62 "self locks" step stool 10 into the use
position to
prevent step stool 10 from folding inadvertently if a user steps on a front
end of lower
step 18. During folding of step stool 10 between the storage and use
positions, top
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and bottom steps 18, 20 remain substantially parallel to one another. Tab 74
prevents
steps 18, 20 from going over center to prevent potential jamming of the step
guide
linkage system. Notch 68 provides clearance for stepped portion 43 of pivot
pin 42 to
permit a flatter fold of step stool 10. Because frame 12 has a Y-
configuration, the
S overall length of step stool 10 does not increase when moved to the storage
position.
Another step stool 110 is disclosed in Figs. 8 and 9. Step stool 110 is
similar in structure and function to step stool 10 as discussed in the
aforementioned
paragraphs and like reference numbers denote like structures between step
stool 10
and step stool 110. In addition to the structures defining step stool 10, step
stool 110
includes a top step 118. Top step 118 includes a side wall 120 having a bottom
edge
122 defining a slot 124 therein, as shown in Fig. 8.
Rear leg 16 of step stool 110 includes a guide pin 164 positioned to
slide in guide slot 62 of step guide link 22 during movement of stop stool 110
between
the use and storage positions. Guide pin 164 is positioned to be received
within slot
124 of top step 118, as shown in Figs. 8 and 9, when step stool 110 is in the
use
position. Edge 122 defines a neck portion 112 of slot 124 which is narrower
than
guide pin 164 and is provided to catch guide pin 164 and hold guide pin 164
within
guide slot 124. Thus, guide pin 164 is formed to provide additional strength
and
stability for step stool 110 by supporting top step 118 when step stool 110 is
in the use
position.
Although the invention has been described in detail with reference to
certain preferred embodiments, variations and modifications exist within the
scope and
spirit of the invention as described and defined in the following claims.
