Road structure – process – or apparatus – Apparatus – Screed or drag
Reexamination Certificate
2002-04-15
2004-02-03
Will, Thomas B. (Department: 3671)
Road structure, process, or apparatus
Apparatus
Screed or drag
C404S084100, C404S118000
Reexamination Certificate
active
06685390
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to concrete screeding apparatus for placing, consolidating and finishing plastic concrete. In particular, the present invention relates to an inverted triangular truss modular screed with an outrigger support. Relevant art may be found in U.S. Class, subclasses 101, 114, 115, as well as others.
2. Description of the Known Art
As will be appreciated by those skilled in the art, wet or plastic concrete must be worked before it sets and forms a hardened slab. Working plastic concrete generally involves consolidating the plastic concrete to evenly distribute water and aggregates throughout the resulting monolith and, subsequently, leveling and finishing the consolidated plastic concrete to appropriately contour the top layer of the plastic concrete.
Consolidating plastic concrete is often performed by vibrating the plastic concrete to evenly distribute water and aggregate materials throughout the monolith of concrete. The vibrations also fracture air pockets trapped inside the monolith and permit the air to escape therefrom. Other pockets of materials, such as sand and gravel or the like, are also shattered so that their components may be more evenly distributed throughout the monolith.
Several tools have been previously proposed for working plastic concrete. These tools include screeds, trowels (both manual and self-propelled), and other tools such as floating pans and the like. Of the former, screeds with strike-offs are commonly employed during initial plastic concrete consolidation while the other types are typically used to finish the top surface of the concrete to a desired smoothness.
Form riding screeds are typically at least ten feet in length and ride upon the forms bounding the concrete monolith. These form-riding screeding apparatus are usually pulled along the form by a series of cables or the like and generally employ remote power to vibrate the smoothing blade. Examples of conventional form-riding screeds are shown in U.S. Pat. Nos. 3,299,786 and 3,541,931.
Screeds may generally be grouped according to the number of operators needed to operate them, support mechanisms necessary for their proper operation, structural shapes, or other meaningful characteristics. It is not uncommon for a screed to meet the criteria for several groups. Screeds with strike-offs are normally employed in “wet” plastic concrete to initially level and consolidate the monolith because the wet plastic concrete typically will not support heavy weights. (“Wet” plastic concrete generally has a slump of between three and ten inches.)
Exemplary multiple operator screeds are shown in U.S. Pat. Nos. 3,110,234, 3,299,786, 3,541,931 and 3,593,627. These devices generally strike-off, vibrate and level plastic concrete in a single pass. They may employ remote power and are typically drawn through plastic concrete by multiple operators. However, they are large and unwieldy and they often require excessive site preparation and cannot be moved quickly about the pour. These devices also suffer from other handicaps associated with maintenance and the like. The configuration of their truss system is such that the vibratory mechanism and strike off blades are essentially an integral part of the screed. As a result of this configuration, the vibrations shake the entire unit, which makes continuous adjustment of alignment characteristics during the screeding operation a matter of course. The concrete leveling blades need to be changed to provide for different finish textures and the like. The strike-off blades occasionally need to be changed to accommodate different plastic concrete mixes. As will be appreciated by those skilled in the art, changing blades on existing screeds requires considerable time.
U.S. Pat. No. 3,110,234 to Oster shows a concrete screeding machine with a rectangular cross-sectional truss beam. The device employs oppositely moving screeds (rather than vibrating screeds) to eliminate side thrust. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally.
U.S. Pat. No. 3,299,786 to Godbersen shows a bridge deck finisher that utilizes a rectangular cross-section truss beam. The apparatus uses spring urging toward the concrete to provide resiliency. The apparatus does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally.
U.S. Pat. No. 3,541,931 to Godbersen shows a concrete finishing mechanism having an adjustable rotating drum. While this device is of only marginal relevance, it too employs a rectangular cross-section truss beam. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally.
U.S. Pat. No. 3,593,627 to Rowe et al. shows a concrete finishing machine movable longitudinally of a road and having a pair of oppositely reciprocating finishing members movable transversely back and forth across the road. The device utilizes a rectangular cross-section truss beam to support the finishing members. The device employs elongated adjustment rods to enable the device to accommodate crowns on roads. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally.
U S. Pat. No. 5,533,831 to Allen shows an obstacle bypass system for concrete finishing tools. The device utilizes a rectangular cross-section to support the finishing members. The device employs pivoting members to enable the device to retract to bypass obstacles. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally.
U.S. Pat. No. 5,988,939 to Allen et al. shows a universal bridge deck vibrating system that utilizes a translating carriage atop a conventional rectangular cross-sectioned beam screed. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally.
Thus, there exists a need in the art for a vibratory screed that may be easily transported about a pour site as well as from pour site to pour site, with minimal preparation time required before use to consolidate and level plastic concrete. The screed width needs to be easily adjustable to accommodate a large range of spans. The working or finishing tools, such as strike-off blades and leveling bars, need to be easily removable to accommodate various concrete mixes that might be spread and the desired texture of the finished concrete monolith. A particularly advantageous apparatus would use a dependable vibratory dispersion system that dampens vibration transmission to the truss system while preventing undesirable down time for camber or pitch adjustments to promote efficient concrete consolidation and leveling.
A need also exists for an improved multiple operator vibratory concrete screeding apparatus that has vibration dampening between the vibratory mechanisms and the trussed beam, has easily changeable strike-off and leveling blades, and has easily adjustable alignment mechanisms, especially for pitch camber alignment.
SUMMARY OF THE INVENTION
In accordance with one exemplary embodiment of the present invention, a screed with a trussed main beam having a cross-section in the geometrical shape of an equilateral triangle is used for finishing
Keisling Trent C.
Keisling Pieper & Scott PLC
Pechhold Alexandra K.
Pieper David B.
Will Thomas B.
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