Title:
FOLDING FRAME SYSTEM WITH CANTILEVER ARRANGEMENT
Kind Code:
A1


Abstract:
A cantilever arrangement for a folding structure is provided. The folding structure is of the type including a plurality of strut members foldable between an open position in which the strut members define a non-zero angle with each other and a closed position in which the strut members define a substantially 0° angle with each other. The cantilever strut arrangement includes a first cantilever strut pivotably adapted to be attached at a first point on the folding structure and a first support member adapted to be attached at a second point on the folding structure and attached at a point on the first cantilever strut. When the folding structure is folded to the closed position, the first cantilever strut member defines a substantially 0° angle with the strut members.



Inventors:
Zeigler, Theodore R. (Alexandria, VA, US)
Application Number:
11/458449
Publication Date:
01/24/2008
Filing Date:
07/19/2006
Primary Class:
Other Classes:
135/123, 135/145
International Classes:
E04H15/50; E04H15/38
View Patent Images:
Related US Applications:
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20050166951Sleeper tentAugust, 2005Russo
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20030192579Beach umbrella with an incorporated radio setOctober, 2003Llamas Garijo
20050103373Standing assist caneMay, 2005Heiss et al.
20050028854Field assembleable wildlife observation shelterFebruary, 2005Erickson et al.
20090308419Umbrella with rearward extending frame and canopyDecember, 2009You
20060118153Foldable umbrella frame having five ribs (IV)June, 2006Ko
20080196753Buffer for Trekking or Nordic-Walking PolesAugust, 2008Heim
20090071517Dual function umbrellaMarch, 2009Zhao



Primary Examiner:
JACKSON, DANIELLE
Attorney, Agent or Firm:
WRB-IP LLP (ALEXANDRIA, VA, US)
Claims:
What is claimed is:

1. A modular frame system, comprising: a frame system comprising a first and a second plurality of scissor assemblies, each scissor assembly of the first and the second plurality of scissor assemblies comprising at least a pair of pivotably connected struts, the scissor assemblies of each of the first and the second plurality of scissor assemblies being pivotably connected end to end by hub assemblies at ends of the struts, the hub assemblies having first and second ends, the scissor assemblies of the first and the second plurality of scissor assemblies being movable from a closed position in which the struts of the at least one strut pair of each scissor assembly are substantially parallel and ends of the struts are substantially adjacent, and an open position in which all of the struts of the at least one strut pair of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance; and a scissor assembly connection arrangement, comprising, for at least one scissor assembly of the first and second plurality of scissor assemblies, a first connecting strut pivotably attached at a first end thereof to a first end of a hub assembly, and a second connecting strut pivotably attached at a first end thereof to a second end of the hub assembly, the second connecting strut being pivotably attached to the first connecting strut, each first connecting strut for the first scissor assembly being removably attached to a corresponding first connecting strut of the second scissor assembly.

2. The modular frame system as set forth in claim 1, wherein the second connecting strut and the first connecting strut are pivotably attached to each other such that, when the first connecting strut of a first scissor assembly is disconnected from a first connecting strut of a second scissor assembly, the struts of the at least one strut pair and the second connecting strut and the first connecting strut are adapted to be pivoted between the closed position in which the struts of the at least one strut pair of each scissor assembly and the second connecting strut and the first connecting strut are substantially parallel, and an open position in which all of the struts of the at least one strut pair of each scissor assembly and the second connecting strut and the first connecting strut define non-zero angles with each other.

3. The modular frame system as set forth in claim 1, wherein the second end of the second connecting strut is pivotably attached to the first connecting strut.

4. The modular frame system as set forth in claim 1, wherein the hub assemblies each include first and second members that are lockable relative to each other to retain the ends of the struts separated by the predetermined distance.

5. The modular frame system as set forth in claim 1, wherein the second connecting strut is in compression when the first and second scissor assemblies are in the open position.

6. The modular frame system as set forth in claim 1, comprising a manual lock associated with second ends of each first connecting strut for locking the second ends of each first connecting strut to the corresponding second end of a corresponding first connecting strut.

7. The modular frame system as set forth in claim 1, comprising a cantilever arrangement comprising a cantilever strut pivotably attached at a first end thereof to an end of a hub assembly, and a second member pivotably attached to an opposite end of the hub assembly and to the cantilever strut.

8. The modular frame system as set forth in claim 7, wherein the cantilever arrangement is foldable such that the cantilever strut and the second member are adapted to be pivoted between the closed position in which at least the struts of the at least one strut pair of each scissor assembly and the cantilever strut are substantially parallel, and an open position in which all of the struts of the at least one strut pair of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance.

9. The modular frame system as set forth in claim 8, wherein, in the open position, the cantilever strut defines a second non-zero angle with struts of the at least one strut pair of each scissor assembly that is different than the non-zero angle defined by the struts of the at least one strut pair with each other.

10. The modular frame system as set forth in claim 8, wherein the second connecting strut and the first connecting strut are pivotably attached to each other such that, when the first connecting strut of a first scissor assembly is disconnected from a first connecting strut of a second scissor assembly, the struts of the at least one strut pair and the second connecting strut and the first connecting strut are adapted to be pivoted between the closed position in which the struts of the at least one strut pair of each scissor assembly and the second connecting strut and the first connecting strut are substantially parallel, and an open position in which all of the struts of the at least one strut pair of each scissor assembly and the second connecting strut and the first connecting strut define non-zero angles with each other.

11. The modular frame system as set forth in claim 7, comprising a cover for covering an exterior of the modular frame system, a portion of the cover being suspended by a first and a second cantilever arrangement and including a doorway, the first cantilever arrangement being pivotably attached to the first plurality of scissor assemblies and the second cantilever arrangement being pivotably attached to the second plurality of scissor assemblies.

12. The modular frame system as set forth in claim 7, comprising a cover for covering an exterior of the modular frame system, a portion of the cover being suspended by a first and a second cantilever arrangement and including a doorway, the first and the second cantilever arrangement being pivotably attached to two respective scissor assemblies.

13. A modular frame system, comprising: a frame system comprising a plurality of scissor assemblies, each scissor assembly of the plurality of scissor assemblies comprising at least a pair of pivotably connected struts, the scissor assemblies of the plurality of scissor assemblies being pivotably connected end to end by hub assemblies at ends of the struts, the hub assemblies having first and second ends, the scissor assemblies being movable from a closed position in which the struts of the at least one strut pair of each scissor assembly are substantially parallel and ends of the struts are substantially adjacent, and an open position in which all of the struts of the at least one strut pair of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance; and a cantilever arrangement attached to at least one of the pairs of pivotably connected struts, the cantilever assembly comprising a cantilever strut pivotably attached at a first end thereof to an end of a hub assembly, and a second member pivotably attached to an opposite end of the hub assembly and to the cantilever strut.

14. The modular frame system as set forth in claim 13, wherein the cantilever arrangement is foldable such that the cantilever strut and the second member are adapted to be pivoted between the closed position in which at least the struts of the at least one strut pair of each scissor assembly and the cantilever strut are substantially parallel, and an open position in which all of the struts of the at least one strut pair of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance.

15. The modular frame system as set forth in claim 13, wherein the second member is a flexible member.

16. The modular frame system as set forth in claim 13, wherein, when the frame system is in an open position, the second member is in tension.

17. The modular frame system as set forth in claim 13, wherein the frame system comprises first and second scissor assemblies arranged parallel to each other when the frame system is in an open position, first and second cantilever arrangements being attached to at least one of the pairs of pivotably connected struts of each of the first and second scissor assemblies, respectively.

18. The modular frame system as set forth in claim 17, comprising a cover for covering an exterior of the modular frame system, a portion of the cover being suspended by the first and the second cantilever arrangement and including a doorway.

19. The modular frame system as set forth in claim 13, wherein, in the open position, the cantilever strut defines a second non-zero angle with struts of the at least one strut pair that is different than the non-zero angle defined by the struts of the at least one strut pair with each other.

20. A cantilever arrangement for a folding structure, the folding structure comprising a plurality of strut members foldable between an open position in which the strut members define a non-zero angle with each other and a closed position in which the strut members define a substantially 0° angle with each other, the cantilever strut arrangement comprising: a first cantilever strut pivotably adapted to be attached at a first point on the folding structure; and a first support member adapted to be attached at a second point on the folding structure and attached at a point on the first cantilever strut, wherein, when the folding structure is folded to the closed position, the first cantilever strut member defines a substantially 0° angle with the strut members.

21. The cantilever arrangement as set forth in claim 20, wherein the first support member is a second cantilever strut.

22. The cantilever arrangement as set forth in claim 21, wherein the first support member is in compression when the folding structure is in the open position.

23. The cantilever arrangement as set forth in claim 20, wherein the first support member is in compression when the folding structure is in the open position.

23. The cantilever arrangement as set forth in claim 20, wherein the first support member is a cable.

24. The cantilever arrangement as set forth in claim 20, wherein the first support member is a tension member.

25. The cantilever arrangement as set forth in claim 20, wherein the first cantilever strut and the first support member define a first cantilever, the cantilever arrangement comprising a second cantilever comprising a second cantilever strut and a second support member, and a cover adapted to be suspended by the first and the second cantilevers and including a doorway.

Description:

BACKGROUND AND SUMMARY

The present invention relates to folding frame systems and, more particularly, to folding frame systems including cantilever arrangements useful for, e.g., doorway arrangements and frame system connection arrangements.

My U.S. Pat. No. 5,444,946, which is incorporated by reference, discloses forming shelters from a plurality of expandable and collapsible frame modules, each frame module comprising a plurality of scissor-strut arrangements connected end-to-end by hub assemblies. The frame modules are particularly well-suited for use in forming shelters in the form of arches.

While shelters such as those in U.S. Pat. No. 5,444,946 are collapsible to facilitate transporting the shelters by means such as trucks to desired locations, there is a practical limit to how large of a shelter can be transported in a single crate, although that limit will, of course, vary depending upon the construction of the shelter. However, in the field, it will often be desirable to connect a plurality of shelters to form one large shelter with a plurality of connected sections, such as for use for large vehicle repairs and maintenance, or for use as a mobile hospital or a command center. It is desirable to provide an arrangement to facilitate the connection of two or more discrete frame systems to form a single, larger frame system.

Particularly with structures in the form of arches, access to the interior of the structures is generally available at only one end of the structure. However, it is often desirable to have access to the structure at various points along the length of the structure, as opposed to merely having access at the ends of the structure. It is desirable to provide an arrangement to facilitate access to a structure comprising a frame system.

In accordance with an aspect of the present invention, a modular frame system comprises a frame system comprising a first and a second plurality of scissor assemblies, each scissor assembly of the first and the second plurality of scissor assemblies comprising at least a pair of pivotably connected struts, the scissor assemblies of each of the first and the second plurality of scissor assemblies being pivotably connected end to end by hub assemblies at ends of the struts, the hub assemblies having first and second ends, the scissor assemblies of the first and the second plurality of scissor assemblies being movable from a closed position in which the struts of the at least one strut pair of each scissor assembly are substantially parallel and ends of the struts are substantially adjacent, and an open position in which all of the struts of the at least one strut pair of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance, and a scissor assembly connection arrangement, comprising, for at least one scissor assembly of the first and second plurality of scissor assemblies, a first connecting strut pivotably attached at a first end thereof to a first end of a hub assembly, and a second connecting strut pivotably attached at a first end thereof to a second end of the hub assembly, the second connecting strut being pivotably attached to the first connecting strut, each first connecting strut for the first scissor assembly being removably attached to a corresponding first connecting strut of the second scissor assembly.

In accordance with another aspect of the present invention, a modular frame system comprises a frame system comprising a plurality of scissor assemblies, each scissor assembly of the plurality of scissor assemblies comprising at least a pair of pivotably connected struts, the scissor assemblies of the plurality of scissor assemblies being pivotably connected end to end by hub assemblies at ends of the struts, the hub assemblies having first and second ends, the scissor assemblies being movable from a closed position in which the struts of the at least one strut pair of each scissor assembly are substantially parallel and ends of the struts are substantially adjacent, and an open position in which all of the struts of the at least one strut pair of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance, and a cantilever arrangement attached to at least one of the pairs of pivotably connected struts, the cantilever assembly comprising a cantilever strut pivotably attached at a first end thereof to an end of a hub assembly, and a second member pivotably attached to an opposite end of the hub assembly and to the cantilever strut.

In accordance with yet another aspect of the present invention, a cantilever arrangement for a folding structure is provided. The folding structure is of the type comprising a plurality of strut members foldable between an open position in which the strut members define a non-zero angle with each other and a closed position in which the strut members define a substantially 0° angle with each other. The cantilever strut arrangement comprises a first cantilever strut pivotably adapted to be attached at a first point on the folding structure and a first support member adapted to be attached at a second point on the folding structure and attached at a point on the first cantilever strut. When the folding structure is folded to the closed position, the first cantilever strut member defines a substantially 0° angle with the strut members.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention are well understood by reading the following detailed description in conjunction with the drawings in which like numerals indicate similar elements and in which:

FIGS. 1A-1C are frontal cross-sectional, side, and top views of frame systems according to an embodiment of the present invention;

FIGS. 2A-2C are front, side, and top views of a shelter according to an embodiment of the present invention;

FIGS. 3A and 3B are views of a portion of a frame system according to an embodiment of the present invention shown in an open position and a closed position, respectively;

FIG. 4A is a side view of a scissor assembly connection arrangement according to an embodiment of the present invention, FIG. 4B is a side view of a scissor assembly connection arrangement together with connected scissor assemblies according to an embodiment of the present invention, and FIGS. 4C and 4D are side and top cross-sectional views of a manual locking arrangement for a scissor assembly connection arrangement according to an embodiment of the present invention; and

FIG. 5A is a side view of a cantilever arrangement according to an embodiment of the present invention and FIG. 5B is a partially cross-sectional view of a portion of the cantilever arrangement as shown in FIG. 5A taken at section 5B-5B.

DETAILED DESCRIPTION

Modular frame system 21 according to an embodiment of the present invention is seen in FIGS. 1A-1C. Frame system 21 of the general type shown in FIGS. 1A-1C can be used to form shelters 23 such as are shown in FIGS. 2A-2C, however, other forms of frame systems than those specifically illustrated can be used to form shelters and other structures other than those specifically illustrated. Also, it will be noted that FIG. 1A shows a frame system 21 in the form of an arch having eight pairs of scissor assemblies connected end-to-end; FIGS. 1B-1C show a frame system 21 similar to that of FIG. 1A having ten pairs of scissor assemblies connected end-to-end; and the shelters 23 shown in FIGS. 2A-2C show covers over frame systems (not shown) that will ordinarily be made up of six pairs of scissor assemblies connected end-to-end, to identify only a few differences between the frame systems of FIGS. 1A and 1B-1C and the shelters of FIGS. 2A-2C. For purposes of discussion, frame systems of the general type described in my U.S. Pat. No. 5,230,196, U.S. Pat. No. 5,444,946, and U.S. Pat. No. 6,141,934, which are incorporated by reference, will be used to describe illustrative, but not limiting, environments in which the present invention can be used.

As seen in FIGS. 1A and 1C, the frame system 21 comprises a first and a second plurality of scissor assemblies 25 and 27. FIG. 1A is a cross-sectional view and shows, on the left side, scissor assemblies 25 and, on the right side, scissor assemblies 27. As seen in FIG. 1A, each scissor assembly 25 and 27 of the first and the second plurality of scissor assemblies comprises at least a pair of pivotably connected struts 29 and 31, and 33 and 35, respectively. As seen in FIG. 1A, the scissor assemblies 25 and 27 of each of the first and the second plurality of scissor assemblies are pivotably connected end to end by hub assemblies 37 at ends of the struts. As seen in FIG. 3A, which will describe the scissor assemblies 25 for purposes of illustration, it being understood that the description applies as well to the scissor assemblies 27, the hub assemblies 37 have first and second ends 39 and 41. The scissor assemblies 25 are movable from a closed position (FIG. 3B) in which the struts 29 and 31 of each scissor assembly are substantially parallel and ends 43 and 45 of the struts 29 and 31 (and 35 and 33), respectively, are substantially adjacent, and an open position (FIG. 3A) in which all of the struts of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance D1.

Components of a scissor assembly connection arrangement 47 are seen in FIGS. 1B-1C and 4A-4D. A scissor assembly connection arrangement 47 can be provided for at least one scissor assembly 25 and 27 of the first and second plurality of scissor assemblies and, ordinarily, is provided between each scissor assembly of the first plurality of scissor assemblies and a corresponding scissor assembly the second plurality of scissor assemblies. As seen, for example, in FIGS. 4A-4D, the scissor assembly connection arrangement 47 can include a first connecting strut 49 pivotably attached at a first end 51 (FIGS. 4A-4B) thereof to a first end 39 of a hub assembly 37. The scissor assembly connection arrangement 47 can also include a second connecting strut 53 pivotably attached at a first end 55 thereof to a second end 41 of the hub assembly 37. The second connecting strut 53 can be pivotably attached to the first connecting strut 49. Ordinarily, the second connecting strut 53 will be pivotably attached at a second end 57 thereof to a substantial midpoint 59 of the first connecting strut 49.

As seen in FIG. 4B, a second end 61 each first connecting strut 49 for the first scissor assembly(ies) 25 is removably attached to a corresponding first connecting strut 49 of the second scissor assembly(ies) 27. In this way, a convenient means of connecting otherwise separate frame systems can be provided. For example, in the embodiment shown in FIGS. 1B-1C, scissor assemblies 25 and 27 at ends of two separate frame systems 21 can be joined together at an ereaction site, while those separate frame systems can be shipped separately, thereby avoiding the need to have all components of a frame system in a single package or shipment.

The second connecting strut 53 and the first connecting strut 49 can be pivotably attached to each other such that, when the first connecting strut of a first scissor assembly 25 is disconnected from a first connecting strut of a second scissor assembly 27, the struts of the at least one strut pair 29 and 31, and 33 and 35, and the second connecting strut 53 and the first connecting strut 49 are adapted to be pivoted between the closed position in which the struts of the at least one strut pair of each scissor assembly and the second connecting strut and the first connecting strut are substantially parallel, and an open position in which all of the struts of the at least one strut pair of each scissor assembly and the second connecting strut and the first connecting strut define non-zero angles with each other.

The hub assemblies 37 in the illustrated embodiments are of the type that each include first and second elongated members 37a and 37b that are lockable relative to each other to retain the ends of the struts separated by the predetermined distance. A manual lock 63 (FIGS. 4A, 5A) that can be in any suitable form can be used to connect the first and second elongated members 37a and 37b. A suitable form of manual lock includes telescoping end portions of the first and second elongated members that can be secured together by a spring loaded button disposed inside an inner one of the end portions that extends through holes in both of the end portions. Other hub assemblies may include multiple discrete components to which struts and other structures are attached. For example, U.S. patent application Ser. No. ______ (Attorney Docket No. 000002-084), entitled FOLDABLE FRAME ELEMENT AND SYSTEM WITH TENSION LOCK, filed on even date herewith, discloses hub assemblies for shelters with outer and inner components that are not connected to each other and are retained at a predetermined distance from each other by other means, in this case by a tension lock arrangement.

The second connecting strut 53 in the embodiments shown in FIGS. 1B and 4A-4B is ordinarily in compression when the first and second scissor assemblies 25 and 27 are in the open position. Such an arrangement in the illustrated embodiments facilitates forming a supporting frame for an outer cover with the various scissors of the first and second plurality of scissor assemblies and the first connecting struts 49 that is substantially continuous, for example, in the sense that it has no significant depression at the location of the first connecting struts. Of course, the arrangement shown in FIG. 4A could be turned upside down so that the second connecting strut is in tension and a depression would be formed.

As seen in FIGS. 4B-4D, a manual lock 65 can be associated with second ends 61 of each first connecting strut 49 for locking the second ends of each first connecting strut to the corresponding second end of a corresponding first connecting strut. The manual lock 65 can be in any suitable form, such as in the form of the manual lock 63 described in connection with the hub assemblies 37. The manual lock 65 illustrated in FIGS. 4C-4D comprises spring loaded buttons 67 disposed in the second ends 61 of each first connecting strut 49. A sleeve 69 is adapted to slide over both of the second ends 61. The buttons 67 extend through holes 71 in the second ends 61 of each first connecting strut 49 and through holes 73 in the sleeve 69 to lock the first connecting struts relative to each other.

As seen in FIGS. 3A and 5A-5B, a cantilever arrangement 75 can be provided and is particularly useful as a means for providing an access point in a frame system or shelter that would ordinarily only have an access point at an end of the structure, such as an elongated arch structure of the type shown in FIGS. 1A-2C. The cantilever arrangement 75 comprises a cantilever strut 77 pivotably attached at a first end 79 thereof to an end of a hub assembly 37, ordinarily the inner end, such as the second end 41 shown in FIG. 5A. The cantilever arrangement 75 also comprises a second member 81 pivotably attached at a first end 83 to an opposite end of the hub assembly 37, such as the first end 39 and to the cantilever strut 77.

Much like the scissor assembly connection arrangement 47, the cantilever arrangement 75 is ordinarily foldable such that the cantilever strut 77 and the second member 81 are adapted to be pivoted between the closed position in which at least the struts 29 and 31 and 33 and 35 of the strut pairs of each scissor assembly 25 and 27 and the cantilever strut are substantially parallel, and an open position in which all of the struts of the at least one strut pair of each scissor assembly define non-zero angles with each other and the ends of the struts are separated by a predetermined distance. However, as seen in, e.g., FIG. 1A-1C and 3A, in the open position, the cantilever strut 77 defines a second non-zero angle with struts 29 and 31 and 33 and 35 of the at least one strut pair of each scissor assembly 25 and 27 that is different than the non-zero angle defined by the struts of the at least one strut pair with each other.

As seen in FIGS. 2A-2C, a cover 85 for covering an exterior of the modular frame system 21 can be provided to form a shelter 23. A portion 87 of the cover can be suspended by a first and a second cantilever arrangement 75. The portion 87 can include a doorway 89 to facilitate ingress and egress from the shelter 23. The first and second cantilever arrangements 75 are pivotably attached to the first plurality of scissor assemblies, e.g., to a first scissor assembly 25, and to the second plurality of scissor assemblies, e.g., to a second scissor assembly 27. Ordinarily, they are attached to the scissor assemblies in the sense that they are pivotably attached to the hubs 37 associated with those scissor assemblies. As seen in FIGS. 1B-1C, the cantilever arrangements 75 can be provided on different scissor assemblies of a single frame system 21 or on scissor assemblies of multiple frame systems, i.e., by scissor assemblies of frame systems that are connected to scissor assembly connection arrangements. Ordinarily, tension members 91 (e.g., FIG. 3A) are provided at various locations along the frame system 21. Inner and outer covers may function as the tension members but, ordinarily tension members in the form of, e.g., cables, will be provided as well as covers. Tension members are disclosed in, e.g., U.S. Pat. No. 5,230,196, U.S. Pat. No. 5,444,946, and U.S. Pat. No. 6,141,934, which are incorporated by reference.

In the embodiment shown in FIGS. 1A, 3A, and 5A-5B, the second member 81 is a flexible member, such as a cable with cable connectors 91 to facilitate attachment to a portion of a hub 37, such as by a bolt, screw, or rivet. If the second member 81 is flexible, when the frame system 21 is in an open position, the second member will ordinarily be arranged so that it is in tension. If the second member 81 is not flexible, such as if a rigid strut is used as the second member, the second member may be arranged so that it is in tension or compression, i.e., by turning the cantilever arrangement shown in FIG. 5A upside down.

As seen in FIG. 5B, the cantilever arrangement 75 ordinarily extends at a different angle from the hub 37 than the struts that are pivotably attached to the hub. This is not, however, necessary and the cantilever arrangement may extend substantially parallel to, e.g., the struts forming the arch, which may be useful if it is desired to provide a larger opening.

In the present application, the use of terms such as “including” is open-ended and is intended to have the same meaning as terms such as “comprising” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

While this invention has been illustrated and described in accordance with a preferred embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.