| 摘要 |
A torsionally stabilized automatic grade control system for finishing plastic concrete is capable of controlling a variety of different elongated, multi-section concrete finishing tools such as a vibratory screed or the like, with or without forms. Skis that support the device facilitate sliding, winch driven movement over and through plastic concrete. Spaced apart, vertically upwardly extending towers support the device; they are disposed periodically along the length of the finishing tool. Each tower comprises a pair of extensible, spaced apart stanchions hinged to the skis and disposed on opposite sides of the tool. An upper strut extends between the stanchions. A sleeve coaxially fitted to each stanchion is synchronized with the opposite sleeve by a rigid transverse bridge. The bridge is adjustably coupled to the strut. The upper portion of the stanchions comprises a hydraulic cylinder. Each cylinder is controlled by an adjacent sensor secured to the strut to maintain the attached tool level. The sensors detect a preestablished laser beacon or the like. Winches move the device along the plastic concrete by spooling cables secured to a fixed point. As the stanchions extend or retract the hinged skis deflect to localize movement of the screed.
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