Excavating – Beneath a body of water – With vessel – propulsion – or anchor structure
Patent
1996-07-01
1998-08-11
Carone, Michael J.
Excavating
Beneath a body of water
With vessel, propulsion, or anchor structure
37312, 440 36, E02F 334, E02F 900, B63H 1908
Patent
active
057910740
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a dredge, and more particularly to a dredge having improved control over positioning and lateral cutter head forces.
BACKGROUND
A dredge usually comprises a floating pontoon, a dredge ladder attached to the pontoon, and a rotating cutter head located at a far end of the dredge ladder. The cutter head is used for cutting or removing dredgeable material as the dredge slews about a substantially vertical axis, and the substantially vertical axis is advanced in a forward direction.
There are a number of methods used for simultaneously advancing the dredge, causing the cutter head to make and maintain contact with uncut dredgeable material, and providing the force necessary to resist the cutting reaction as the cutter head slews and rotates.
A first method uses a three-wire system in which a wire extends laterally and forwardly from each of the two sides of the pontoon. Each of the two wires is anchored ashore, passes through a respective pulley attached to the dredge ladder, and continues on to a respective slew winch on the pontoon or ladder. The slew winches exert forces on the two wires to pull the dredge forward onto the face of the uncut dredgeable material, and laterally to resist the reaction from the cutting force as the cutter head cuts the dredgeable material. A third wire, the tail wire, passes from an anchor point to a tail winch, and this is used to position the dredge longitudinally.
The three-wire system is currently the least expensive dredging system. It is effective in dredging ponds which are wide, shallow, have good access for changing anchoring positions, and have low banks. However, in ponds which do not satisfy these criteria, the three-wire system is less effective. Specifically, in narrow, deep ponds, the three-wire system has the following disadvantages: small; the face; cutting forces; and embedded in the face of the material being dredged, or present a hazard to operating personnel.
These disadvantages are alleviated to a certain extent by a conventional spud dredge in which a long vertical post, or spud, provides a pivot point at the stern of the pontoon. The spud is mounted on a sliding carriage, and the cutter head is forced forward against the face by causing the carriage to move backwards relative to the dredge.
In an arrangement similar to the three-wire system, lateral force to resist the cutting reaction is provided in a conventional spud dredge by slew winches which pull on wires extending forwardly and laterally from the dredge ladder (see for example, U.S. Pat. Nos. 4,399,623; 4,445,290; and 5,145,425). However, in the spud dredge, these wires are usually anchored to the pond bed.
One of the disadvantages of the conventional spud dredge is that the spud may not provide an anchor which is firm enough. This is especially relevant when a spud dredge is used for tailings recovery in which the pond bed may be particularly soft. In order to provide a sufficiently firm anchor, the spud must be driven deeply into the pond bed, and, in this case, the bending moments on the spud and the dredge may be large.
Thus, it is desirable to provide a dredge which can be positioned accurately and firmly, and which uses no aerial wires which can foul equipment or present a hazard to operating personnel.
SUMMARY OF THE INVENTION
The present invention consists in a dredge comprising: and a second leg having a second effective longitudinal axis, the first leg and the second leg being oriented such that the first effective longitudinal axis and the second effective longitudinal axis diverge from one another toward their forward ends and define an included angle, the included angle being less than 180 degrees; of the first leg for anchoring the first leg to an adjacent substrate; end of the second leg for anchoring the second leg to the adjacent substrate; and the second leg and rearwardly of them, for collecting dredgeable material; the collection means to slew between the first and second leg about a substantially vertical axis; and
REFERENCES:
patent: 1792065 (1931-02-01), Bowers
patent: 1913670 (1933-06-01), Hindes
patent: 2850814 (1958-09-01), Elliott, Jr.
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patent: 3739503 (1973-06-01), Barker et al.
patent: 4399623 (1983-08-01), Neumann
patent: 4445290 (1984-05-01), Oules
patent: 4547162 (1985-10-01), Little
patent: 4676052 (1987-06-01), Hawk
patent: 5145425 (1992-09-01), Little
patent: 5311682 (1994-05-01), Sturdivant
Carone Michael J.
Minpro Australia N.L.
Pezzuto Robert
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