U.S. patent number 3,844,609 [Application Number 05/424,402] was granted by the patent office on 1974-10-29 for folding bookrack for stackable chairs.
Invention is credited to Robert J. Bomber.
United States Patent |
3,844,609 |
Bomber |
October 29, 1974 |
FOLDING BOOKRACK FOR STACKABLE CHAIRS
Abstract
A substantially flat rack is suspended beneath the underside of
a chair by four supporting links which are each loosely pivoted at
their upper end to the underside of the chair and are each loosely
pivoted at their lower end to a corresponding corner of the rack.
The length of the rear links plus the distance between the front
and rear pivots on the rack is greater than the length of the front
links plus the distance between the front and rear pivots on the
underside of the chair. This provides an over-center locking action
when the rack is swung upwardly as far as it will go toward the
underside of the chair to hold the rack in a collapsed
position.
Inventors: |
Bomber; Robert J. (Green Bay,
WI) |
Family
ID: |
23682506 |
Appl.
No.: |
05/424,402 |
Filed: |
December 13, 1973 |
Current U.S.
Class: |
297/188.12;
211/119; 211/118; 297/239 |
Current CPC
Class: |
A47C
3/04 (20130101); A47C 7/62 (20130101) |
Current International
Class: |
A47C
3/04 (20060101); A47C 3/00 (20060101); A47C
7/62 (20060101); A47c 007/62 () |
Field of
Search: |
;297/192,188,189,190,239,160,161,162 ;211/118,119,113,181 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McCall; James T.
Attorney, Agent or Firm: Wheeler, Morsell, House &
Fuller
Claims
What is claimed is:
1. A folding bookrack for use in combination with a stackable
chair, said bookrack comprising a substantially flat rack which is
small enough to fit in the space between the four legs of said
chair, four supporting links each loosely pivoted at its lower end
to said rack at a corresponding lower pivot point for suspending
the rack from the underside of said chair, each of said supporting
links being loosely pivoted at its upper end to the underside of
the chair at a corresponding upper pivot point, and said pivot
points being so positioned as to provide an over-center locking
action when said rack is swung upwardly as high as it will go
toward the underside of said chair.
2. The combination defined in claim 1 wherein the distance from the
upper rear pivot points to the lower rear pivot points plus the
distance from the lower rear pivot points to the lower front pivot
points is greater than the distance from the lower front pivot
points to the upper front pivot points plus the distance from the
upper front pivot points to the upper rear pivot points, thereby
providing an over-center locking action when said rack is swung
upwardly as high as it will go toward the underside of said
chair.
3. The combination defined in claim 2 wherein the distance from
each upper pivot point to the corresponding lower pivot point are
all equal, the distance from the lower rear pivot points to the
corresponding lower front pivot points being greater than the
distance from the upper rear pivot points to the corresponding
upper front pivot points.
4. The combination defined in claim 1 wherein each of said
suspension links has a first hook on its upper end for pivotally
engaging the underside of said chair and has a second hook on its
lower end for pivotally engaging a corresponding corner portion of
said rack.
5. The combination defined in claim 4 wherein the underside of said
chair has a front cross brace that extends transversely across the
front underside of the chair and has a rear cross brace that
extends transversely across the rear underside of said chair, two
of said suspension links being pivotally suspended from said front
cross brace and the other two suspension links being pivotally
suspended from said rear cross brace.
6. The combination defined in claim 5 wherein said rack has a front
cross brace that extends transversely across the front of said rack
and a rear cross brace that extends transversely across the rear of
said rack, two of said suspension links being pivotally attached at
their lower end to the front cross brace of said rack, and the
other two suspension links being pivotally attached at their lower
end to the rear cross brace of said rack.
Description
BACKGROUND OF THE INVENTION
This invention relates to folding book racks for chairs which can
be stacked one on top of the other. Such book racks must extend far
enough below the seat of the chair to receive an average size stack
of school books and yet fold up high enough to avoid interfering
with the stackability of the chairs. Such bookracks also preferably
include means for locking the rack in its folded position to avoid
interfering with the stacking of the chairs.
The principal object of this invention is to provide a folding
bookrack which meets the above-noted requirements.
Another object of this invention is to provide a folding bookrack
of the above-noted character which is simple in structure and easy
to install.
Other objects and advantages of the invention will be apparent to
those skilled in the art from the description which follows.
SUMMARY OF THE INVENTION
A substantially flat rack is suspended beneath the underside of a
chair by four supporting links which are each loosely pivoted at
their upper end to the underside of the chair and are each loosely
pivoted at their lower end to a corresponding corner of the rack.
The length of the rear links plus the distance between the front
and rear pivots on the rack is greater than the length of the front
links plus the distance between the front and rear pivots on the
underside of the chair. This provides an over-center locking action
when the rack is swung upwardly as far as it will go toward the
underside of the chair.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of one illustrative folding
bookrack of this invention suspended from the underside of a
stackable chair.
FIG. 2 is a fragmentary rear elevation view of the bookrack of FIG.
1 and the structure which supports it, the bottom and back of the
chair being removed to expose the upper pivot points of the
bookrack supporting links.
FIG. 3 is a plan view of the rack member of the bookrack shown in
FIGS. 1 and 2.
FIG. 4 is a side elevation view of two of the chair and bookrack
assemblies shown in FIG. 1 with the bookracks in their folded
condition and the chairs stacked one on top of the other.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Although the disclosure hereof is detailed and exact to enable
those skilled in the art to practice the invention, the physical
embodiments herein disclosed merely exemplify the invention which
may be embodied in other specific structure. The scope of the
invention is defined in the claims appended hereto.
The drawings show one illustrative embodiment of the invention
suspended below a stackable chair 10 of the sled base type having a
unitary molded plastic seat and back member 12 which is supported
by a metal framework 14 (FIG. 2). The framework 14 includes two
front legs 16 (FIG. 1), two rear legs 18, an upper front cross
brace 20, an upper rear cross brace 22, two chair supporting strips
24 which are attached to cross braces 20 and 22, and two lower side
braces or runners 26 which extend between the bottom ends of front
legs 16 and rear legs 18. The portion of the framework 14 that
includes elements 16, 18, 20, 22 and 26 is preferably made from a
single piece of round steel rod or tubing which is formed into the
shape shown in FIGS. 1 and 2 and is welded together at its ends 28
(FIG. 2) to form a continuous supporting member.
The two chair supporting strips 24 are curved to match the shape of
both the cross braces 20 and 22 and the underside of the seat and
back member 12. Four supporting cones 30 (FIG. 1) are formed in the
bottom of seat and back member 12 and are tapped to receive bolts
32 that extend through openings in the chair supporting strips 24.
The chair supporting strips 24 are made of steel and are welded to
the cross braces 20 and 22. The bottom portion of legs 16 and 18
are spread apart slightly at 33 (FIG. 2) to permit the chair to be
stacked upon the seat of another chair of the same type as shown in
FIG. 4.
A substantially flat rack member 34 (FIGS. 2 and 3) is suspended
from the underside of the above-described chair to support books or
other objects that the occupant of the chair may be carrying when
he or she sits down in the chair. In this particular embodiment of
the invention, the rack 34 is made of three pieces of steel rod: a
relatively long rod 36 which is bent into an indulating shape as
shown in FIG. 3 to form a rectangular supporting platform or grid,
a front cross brace 38 which is welded to the front edge of the
supporting platform, and a rear cross brace 40 which is welded to
the rear edge of the supporting platform.
The rack member 34 is suspended beneath the underside of the chair
by two rear suspension links 42 and two front suspension links 44,
each of which is loosely pivoted at its upper end to the underside
of the chair and is loosely pivoted at its lower end to the rack
member 34. The rear suspension links 42 are bent in a hook 46 at
their upper end to pivotally engage upper cross brace 22 and are
bent in a hook 48 at their lower end to pivotally engage lower
cross brace 40. The front suspension links 44 are bent in a hook 50
at their upper end to pivotally engage upper cross brace 20 and are
bent in a hook 52 at their lower end to pivotally engage lower
cross brace 38. Each of the hooks 46, 48, 50 and 52 define a
corresponding pivot point which is positioned in the center of the
eye of the corresponding hook. In the description which follows,
each of the eight pivot points will be identified by the reference
numeral of the hook that defines the point, e.g. pivot point 46 is
the point defined by hook 46, and so on.
Referring to FIG. 1, the distance A from pivot point 46 to pivot
point 48 plus the distance B from pivot point 48 to pivot point 52
is greater than the distance C from pivot point 46 to pivot point
50 plus the distance D from pivot point 50 to pivot point 52. Since
A plus B is greater than C plus D, an over-center locking action
will be produced when the rack member 34 is swung upwardly as far
as it will go toward the underside of the chair as shown in FIG. 4.
The over-center locking action is evident from the fact that the
pivot point 48 of members 36 and 42 has been moved upwardly past
the position where members 36 and 42 make an angle of 180.degree.
with each other. Once the book rack has been snapped up into the
position shown in FIG. 4, it will remain there until downward force
is applied to rack member 34 to move the members 36 and 42
downwardly over-center, i.e., past the position where the members
36 and 42 make an angle of 180.degree. with each other.
The over-center locking action of this invention is important
because it permits the folding bookrack to be locked in its
upwardly folded position without any additional latch means and
permits the bookrack to be moved to its lower open position for use
by a downward push on rack member 34 or front suspension links 44.
In this particular embodiment, the inequality between distances A
plus B and C plus D is achieved by making the distance B greater
than the distance C, which allows the distances A and D to be equal
to each other. This simplifies the construction of the invention
inasmuch as it permits a common suspension link to be used for all
four of the suspension links 42 and 44. However, it is possible if
desired to achieve the same over-center locking effect by making
the distance A greater than the distance D while keeping the
distance B and C equal to each other.
It should be noted that this embodiment of the invention is very
easy to install. All that is required for installation is to hang
the hooks 46 and 50 over the braces 22 and 20 respectively. The
bookrack can be just as easily removed by disengaging the hooks 46
and 50 from the corresponding braces 22 and 20.
As shown in FIG. 2, the rear suspension links 42 are preferably
positioned inside of the chair supporting strips 24 and the front
suspension links 44 are preferably positioned outside of the chair
supporting strips 24. This position allows the rear suspension
links 42 to act as abutment members that prevent books from sliding
out the back of rack 34.
* * * * *