Fire escape – ladder – or scaffold – Self-sustaining – Scaffold horse
Reexamination Certificate
2001-07-03
2003-09-02
Stodola, Daniel P. (Department: 3634)
Fire escape, ladder, or scaffold
Self-sustaining
Scaffold horse
C182S186500, C182S153000, C182S224000, C248S163100, C248S188000, CD25S067000
Reexamination Certificate
active
06612401
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a sawhorse assembly. More particularly, the invention relates to a bracket assembly for use in a sawhorse, barricade and/or scaffolding type devices.
BACKGROUND OF THE INVENTION
Although the original use for a sawhorse was to provide a rack to support something being sawed, today's professional construction workers, farmers and home hobbyists use sawhorse type devices to create a work surface, a raised storage surface, a barricade, scaffolding and other similar support structures as well as to support items to be sawed. All further references to sawhorses are meant to include barricades, scaffolding and other similar structures.
Many sawhorse brackets have been developed over the years but each seems to specialize in only one primary aspect of the bracket and none have all of the desired features. Typical users, such as construction workers and farmers, want a sawhorse that provides many different features. For the busy worker, quickness and ease of assembling and disassembling the sawhorse without any tools is important. For the worker who is using the sawhorse as a support structure for cutting lumber or other materials, it is highly desirable that the structure of the sawhorse itself (both bracket and cross member) be protected from the saw blade.
The capability of handling heavy loads is important, especially in commercial construction. Stability and durability come into play when the pieces of the sawhorse are put together. Each piece needs to be designed such that it disperses the stress forces across as broad an area as possible to provide maximum support with minimum stress on each piece. An example of this is the fitting of the wooden legs flush against the bracket to spread the load stress points over an extended area.
Everyone is interested in low cost; and, therefore, the product should be easy to manufacture and the lumber that is used for the legs and cross member should be reusable for other things—they should not be fungible goods. Construction sights are not known for gentleness and any tool or device that is intended for use on-site must be able to withstand rough treatment.
Although there are several sawhorse brackets on the market, none have all of the desired features as described above. For example, U.S. Pat. No. 4,192,406 by Mitchell does not meet the above requirements for several reasons. First, the complex requirements of the manufacturing process (using a single, integral sheet of stiff bendable material, cutting all the required intricate patterns and then bending all of the lips, tabs and securement flaps into place) greatly increase the cost of manufacturing and limit the thickness of the material that can be used. This would possibly limit the amount of load that the sawhorse can handle at an amount less than desired.
Additionally, Mitchell's '406 patent uses only two spaced tabs (cut and bent from the side walls) to support each end of the cross member which must handle all forces of the load. When the sawhorses are loaded to a high, desired capacity, the stress forces will tend to cause the metal to distort. This distortion makes the sawhorse unstable and causes problems with disassembly and reassembly operations. The load factors must be dispersed through a broader area to prevent this type of problem. Similarly, the stops that are located in the leg segments also are bent tabs which are susceptible to being forced upward when a load is applied to the sawhorse, thus defeating the purpose of the stops to have the tops of the wooden legs fit flush against metal in the bracket.
U.S. Pat. No. 5,484,037 by Neumarkel also does not meet the set of requirements outlined above. Although the '037 patent discloses an elevated cross member, the elevation does not appear to be enough so that a saw blade will not encounter the metal brackets. The '037 patent also does not disclose nor discuss the protection of the cross member itself. Similarly, it appears that the lumber for the legs must be cut at angles such that the legs fit flush against the top member. By cutting the lumber, the lumber is no longer totally reusable as desired. If the lumber for the legs is not cut, the leg will only contact the bottom of the sleeve along one edge of the sleeve so all forces of the leg pushing upward are now focused on a single line instead of a broader area.
The stability of the '037 design is also of concern. The bottom of the sleeve is positioned on top of the intersection of the two leg sockets and overlaps each leg by less than one-half the width of the leg. This intersection of the two legs and the center tube is welded. This single weld point does not appear to provide sufficient stability especially when considering that the bottom of the center sleeve receives the full force of the load from the top and receives the pressure of the two wooden legs pushing upwardly through the leg sockets. Therefore, when a load is placed on the sawhorse, the forces press downward on the bottom of the tube and the legs tend to spread outward while the top ends of the legs tend to push up through the leg sockets with pressure on the top member. If the pressure from the two legs is uneven, there would be a tendency for the weld to weaken or break. Marketing literature for the '037 design only rates the bracket at 750 pounds. This is not acceptable for many commercial and farm uses.
The cost of manufacturing tubing as opposed to flat metal also is much higher and any openings in the tubing must be made by drilling which is more expensive than a method such as punching which can be used on flat metal. The use of standard tubing also presents the problem of improper fit. The lumber used for the legs, as shown in the published patent, is not tightly encased by the tubing. This means that the legs will flex within the tubing causing continual wear on the wooden legs. Another concern of using tubing relates to the corners. Because the corners of the tubing are rounded and the corners of the lumber used for the legs and support piece are squared, the tubing cannot provide the desired flush fitting of the pieces.
In general, the approach of the art has been to focus on a particular aspect and none of the above-described brackets or others found in the prior art have been able to adequately handle heavy loads on easy-to-assemble/disassemble sawhorses that are easy and inexpensive to manufacture and do not treat the lumber used for the cross member and legs as fungible goods. It would, therefore, be a significant advancement in the art to provide an improved sawhorse bracket that provides all of these features.
SUMMARY OF THE INVENTION
Accordingly, this invention is directed to an improved sawhorse bracket that is easy and inexpensive to manufacture, does not require the more-expensive metal tubing used in the prior art, uses standard dimension lumber for the cross member and legs, does not require the trimming of the lumber for the legs to fit flush against the bracket, is easily assembled and disassembled, provides away to elevate materials that are being cut such that the saw blade cannot damage the sawhorse bracket or cross member, and is capable of handling heavy loads.
In fulfillment of the objectives stated above, the present invention is directed to an improved sawhorse. The present invention accomplishes this objective by using a structure comprising four legs, a cross member having two ends, and two brackets wherein each bracket has a C-shaped collar which is adapted to receive one of the ends of the cross member and two leg receptacles which are attached to a front side and a back side of the collar, wherein each of the leg receptacles is adapted to receive one of the four legs of the sawhorse.
REFERENCES:
patent: 302945 (1884-08-01), Sargent
patent: 936945 (1909-10-01), Rice
patent: 1542048 (1925-06-01), Forester
patent: 1597555 (1926-08-01), Tolmie
patent: 1953012 (1934-03-01), Gerrard
patent: 2501656 (1950-03-01), Anderson
patent: 3042144 (1962-07-01), Larson
patent: 3289789 (1966-12-01), L
Nolen, Jr. Charles W.
Price Tommy
Layman Elizabeth
Stodola Daniel P.
Thompson Hugh B.
Tripp Karen B.
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