Excavating – Beneath a body of water – Suction
Reexamination Certificate
2000-06-16
2001-11-20
Shackelford, H. (Department: 3671)
Excavating
Beneath a body of water
Suction
C037S317000, C037S350000
Reexamination Certificate
active
06318005
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements in dredges and, in particular, to an improved suction auger head used with a ladder suspended from a barge.
PRIOR ART
U.S. Pat. No. 5,060,404 discloses a suction auger-type dredge head on a ladder suspended from a barge. The ladder pivots at one end while the opposite free end, carrying the auger or cutter head, is lowered or raised to a depth to reach and work the bottom. The auger is partially surrounded by a shroud having a center section and outer sections pivotal at opposite edges of the center section. One or the other pivoting shroud sections is raised or opened to admit bottom material to the cutting side of the auger depending on the direction the head is being moved. The shroud serves to confine the suction developed by a pump to the zone of the auger. The head can be pivoted on the ladder about an axis displaced from the head to reduce, to some extent, the effect that a change in the ladder angle or inclination has on the attitude of the shroud relative to the bottom surface and cut that the auger is making.
SUMMARY OF THE INVENTION
The invention provides dredging apparatus with a suction auger head that achieves improved operating efficiency with a novel auger shroud assembly. The shroud assembly has a generally cylindrical arcuate configuration that is formed by a series of arcuate sections. The sections are movable relative to the ladder depending on the depth and direction of travel of the auger head.
In the disclosed arrangement, the auger head shroud assembly has a center section lying between oppositely extending forward and rear sections. All of the sections are pivotal, in unison, about an axis coincident with the axis of rotation of the auger. The forward and rear sections are each independently pivotal about a respective axis adjacent its edge proximal to the center shroud. Pivotal shroud assembly movement about the auger axis adjusts for differing depth angles of the ladder. One or the other of the forward and rear sections is pivoted open depending on the direction of movement of the dredge. More specifically, the forward or rear section leading the auger in the direction of movement is pivotally opened while the other section remains closed adjacent the periphery of the auger.
The disclosed shroud construction enables the shroud to closely hug the bottom surface immediately ahead of the auger in either forward or reverse directions. Consequently, turbidity is minimized at the auger head and, as a result, high dredging efficiency is achieved.
REFERENCES:
patent: 516090 (1894-03-01), Gullmann
patent: 3738029 (1973-06-01), Harmon
patent: 3971148 (1976-07-01), Deal
patent: 4083134 (1978-04-01), Oterdoom
patent: 4146982 (1979-04-01), Norisugi
patent: 5060404 (1991-10-01), Lipford
patent: 5651200 (1997-07-01), Walsh
patent: 5732487 (1998-03-01), Van De Kerckhove
Ellicott Machine Corporation International
Pearne & Gordon LLP
Shackelford H.
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