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.

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.

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.