Fire escape – ladder – or scaffold – Unitary foldable – rigid scaffold or ladder – Trestle
Reexamination Certificate
2001-09-20
2003-08-05
Johnson, Blair M. (Department: 3634)
Fire escape, ladder, or scaffold
Unitary foldable, rigid scaffold or ladder
Trestle
C182S225000
Reexamination Certificate
active
06601675
ABSTRACT:
BACKGROUND
1. Field of Invention
This invention relates to folding sawhorses, trestles, and the like, referred herein a sawhorses. The purpose of the invention provides for a sawhorse which self locks resulting in a sawhorse that is easy to use, can be made from standard off-the-shelf materials, is very stable without any specialized locking hardware, and has more functional uses than a standard sawhorse.
2. Description of Prior Art
A number of patents issued on various sawhorses relate, however none disclose the features of the present invention. Several disadvantages exist. One such disadvantage is the inability to self-lock without the addition of special hardware or specific manual procedures as illustrated by U.S. Pat. No. 4,756,385 and U.S. Pat. No. 4,429,765.
The invention uses opposing forces to provide a natural self-locking capability, induced by the opening and closing of the sawhorse. The resulting opposition of the two opposing forces produces a fixed and stable sawhorse when opened, without having to tighten or twist or adjust any specialized bolts, pins, ropes, chains or arms.
The ability to use of simple off-the-shelf hinges and screws in the invention make it easy and cheap to manufacture.
Another disadvantage illustrated by U.S. Pat. No. 4,620,613 is the load-bearing requirements placed upon the hinges, which provide the folding capabilities. This invention places the load upon the main structure and only uses hinges mainly for positional alignment of the main structure resulting in a sawhorse, which can withstand heavy usage and loading without failures or excessive wearing of the hinges.
Many other sawhorses illustrate various designs for being foldable or collapsible. These designs require spring loaded bolts or hinges to induce the forces necessary to have the sawhorses close as illustrated in U.S. Pat. Nos. 4,429,765 and 4,620,613. This invention is collapsible without requiring springs and closes automatically upon the release of the opposing forces and lifted from the ground.
Another disadvantage illustrated by U.S. Pat. Nos. 4,756,385, 2,825,606 and 4,620,613 is the ease of use. The present invention can be deployed using one hand and unemployed the same. This makes it easier to use and more convenient. There are no complicated actions or procedures needed to open and lock the invention as well as unlock and collapse the invention. In the unlocked state, the invention tends toward a folded position when carried.
A disadvantage illustrated by U.S. Pat. No. 4,113,056 is the inability to provide a stable work surface free from falling due to drifts in load or work forces. The clamping action of the invention holds or grips materials placed in the jaws. A tabletop with two screws protruding at each end can easily be held by this invention, resulting in a sturdy worktable. The locking jaws make a functional holder. There are many uses for the holding capabilities such as holding a saw for sharpening. The invention can hold guides to ensure materials won't slip or move. The locking feature makes this invention resistant to the affects of unleveled work surfaces and the rigidity doesn't allow creeping.
A disadvantage illustrated by U.S. Pat. Nos 6,021,866, 4,756,385, 4,620,613, 4,429,765, 4,319,663 and 2,825,606 is the restriction to using hand clamps for holding material. The designs of these prior an examples don't provide usable surface shapes for easily using hand clamps to hold work. This invention when in the locked position, maintains a rigid flat top allowing the easy use of commercially available clamps,
SUMMARY
In accordance with the present inventions a sawhorse comprising a trestle structure using two opposing forces to create a locking action made using standard off-the-shelf components where the invention acts like a fixed structured sawhorse while locked and a foldable sawhorse when not locked maximizing it's ease and diversity of use.
OBJECTS AND ADVANTAGES
Accordingly, several objects and advantages of my invention are:
(a) to provide a stable sawhorse that resist moving, closing, creeping or collapsing due to strain while in use;
(b) to provide a folding sawhorse which can be deployed with a single hand and single action and collapsed as easily for compact storage;
(c) to provide a sawhorse that gives excellent function without the need for nothing more also simple hinges with no spring loaded bolts or hinges, no ropes, chains or adjustment arms;
(d) to provide a sawhorse easily manufactured from standard off-the-shelf components and require a minimum amount of material;
(e) to provide a load bearing sawhorse, capable of handling heavy loading without deforming, loosing stability, shifting or causing excessive wear on components;
(f) to provide a sawhorse capable of retaining functionality when used on unleveled work surfaces;
(g) to provide a sawhorse where most load bearing forces are maintained by the main structural members and not the hinges used to allow folding;
(h) to provide a sawhorse based upon, opposing forces to make it a rigid sawhorse without wobble when in use and still be collapsible when not in use;
(i) to provide a sawhorse that is very light weight and easy to carry and move;
(j) to provide a sawhorse with alternative uses by incorporating a set of locking jaws capable of folding many different items or materials;
(k) to provide a sawhorse which can be used to provide a quick and easy assembly of a work surface which can combine with two sawhorses and provide a stable and locked surface that won't wobble of shift with use;
(l) to provide a sawhorse where changes in dimensions won't change the self locking character of the invention when differing sizes are desired;
(m) to provide a sawhorse which can lock into runners to provide resistance and stability to wind and can be used as a barricade or warning device,
(n) to provide easy use of guides to hold and maintain material being worked which are easy to position, change and remove.
(p) to provide a sawhorses which can be made of differing materials such as wood, molded plastic or metal and still operate with the same locking forces.
(p) to provide a sawhorse where clamps can be easily used to hold the work.
Further objects and advantages of my invention will become apparent from a consideration of the drawings and ensuing description.
REFERENCES:
patent: 3713512 (1973-01-01), Reece
patent: 4102555 (1978-07-01), Tobolski
patent: 4325463 (1982-04-01), Taylor
patent: 4429765 (1984-02-01), Garcia
patent: 4620613 (1986-11-01), Albertson
patent: 4703830 (1987-11-01), Parker
patent: 4790411 (1988-12-01), Ottoson
patent: 5628382 (1997-05-01), Hill
patent: 5758744 (1998-06-01), Forino
patent: 6142256 (2000-11-01), Dirk, II
patent: 6164413 (2000-12-01), Sagol
Cherskov & Flaynik
Johnson Blair M.
Thompson Hugh B.
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