WO1983000891A1

WO1983000891A1 - Improvements in dredges

Info

Publication number: WO1983000891A1
Application number: PCT/AU1982/000155
Authority: WO
Inventors: Pty. Ltd. Jaden
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-09-11
Filing date: 1982-09-13
Publication date: 1983-03-17
Anticipated expiration: 1984-03-11

Abstract

Dans une drague du type ayant une roue de dragage rotative (19) entraînée par un moteur et montée sur le front d'une structure en échelle (11) pivotant sur la coque (10) de la drague, une conduite d'aspiration (20) sortant le matériau excavé, la roue (19) de la drague, avec des organes d'excavation (28, 39) partant d'un moyeu (27, 38), tourne dans le sens qui amène ses organes d'excavation (28, 39) vers le bas en avant du moyeu (27, 38), et en arrière sous ce dernier, faisant avancer ainsi la drague en même temps que se fait l'excavation. Les organes d'excavation peuvent consister en deux séries de bras de coupe (28) espacées axialement ayant des pointes tranchantes (29) à leurs extrémités extérieures et des lames (30) sur leur bord d'attaque, les bras (28) des deux séries étant inclinés de manière opposée pour pulser le matériau excavé vers l'intérieur depuis les côtés vers une bouche située au centre (32) d'une chambre d'admission (42) menant à la conduite d'aspiration (20).In a dredge of the type having a rotary dredging wheel (19) driven by a motor and mounted on the front of a ladder structure (11) pivoting on the hull (10) of the dredger, a suction pipe (20 ) taking out the excavated material, the wheel (19) of the dredge, with excavating members (28, 39) starting from a hub (27, 38), turns in the direction which brings its excavating members (28 , 39) down in front of the hub (27, 38), and back under the latter, thus advancing the dredge at the same time as the excavation is carried out. The excavating members may consist of two series of axially spaced cutting arms (28) having sharp points (29) at their outer ends and blades (30) on their leading edge, the arms (28) both series being inclined in opposite directions to pulsate the excavated material inwards from the sides towards a mouth situated in the center (32) of an inlet chamber (42) leading to the suction pipe (20).

Description

Title; "IMPROVEMENTS IN DREDGES"

^' BACKGROUND OF THE INVENTION (1) Field of the Invention

This invention relates to improvements in dredges. (2) Brief Description of the Prior Art

A well-known type of dredge excavates by means of a rotary dredge wheel which is mounted on the front of a ladder frame hinged at its rear to the dredge hull, the front part of the hull being divided so the ladder - can be lowered to working depth, or raised by any suitable lifting gear. The dredge wheel is provided with a peripheral series of^'dredge buckets, and is driven, through a gearbox, by a hydraulic motor at the front of the ladder frame, so that each bucket in turn is brought forwardly, under the dredge wheel, and up, front of the wheel, to scoop up material from the sea bed, this material being received in a suction line connected to a pump on the dredge hull, and expelled from the pump through a floating or pontoon-carried conduit to the shore. Such a dredge is usually advanced by the use of two spuds mounted on the hull in vertically slidable manner, one being slidable through a carriage which is longitudinally movable on the hull. When this spud is driven into the sea bed, the hull^" can be advan- ced relative to it, after which the second spud may be driven and the first raised and returned forwardly on the hull, and so on. Either spud serves as a pivot about which the dredge may be slewed by means of slewing cables from anchors dropped to both sides^' of the bucket wheel and carried, by way of sheaves on the ladder frame, to winches by which one slewing cable may be slackened as the other is tensioned to slew the dredge.

The general object of the present invention is to provide a dredge in which the dredge wheel assembly is particularly efficient, and enables the construction and operation of the dredge to be greatly simplified. BRIEF SUMMARY OF THE PRESENT INVENTION With the foregoing and other objects in view the invention resides broadly in a dredge of the type having a hull, a frame mounted on the hull and having mounted at its front a motor-driven rotatable dredge wheel with a series of excavating members extending from its hub, means for lowering or raising the frame and the dredge wheel thereon, and a suction duct on the frame to receive and convey material excavated by the dredge wheel, wherein the dredge wheel is rotated in the direction to cause its excavating members to excavate while moving downwardly in front of, and rearwardly below, the hub. The excavating members may consist of two series of cutter arms radiating from the hub, the two series being spaced axially in relation to the hub. The cutter arms of the two series may be pitched oppositely to urge material excavated thereby to be impelled inwardly from both sides, and the suction duct may lead rearwardly from an intake chamber with an opening or mouth at the front located below the dredge wheel hub and between the two series of cutter arms. Other features of the invention will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be readily under¬ stood and carried into practical effect, reference is now made to the accompanying drawings, wherein:-

FIG. 1 is a side elevational view of a dredge according to the invention,

FIG. 2 is a side view, to larger scale, of the dredge wheel of the dredge,

FIG. 3 is a front elevational view of the dredge wheel shown in FIG. 2, and FIG. 4 is a side elevational view of a dredge wheel according to an alternative embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The dredge illustrated includes a hull 10 of which 5 the front part is divided centrally to enable a ladder frame 11, the rear end of which is pivoted about a transverse axis at 12 to a pair of mounting brackets 13 on the hull, to be lowered, as shown in FIG. 1 from its more or less horizontal travelling position to a 10 working position. The ladder frame is raised or lowered by means of a winch 14, its cable 15 being engaged with sheaves 16 on a gantry 17 straddling the front of the dredge hull, and sheaves 18 on the ladder frame.

At its front the ladder- frame 11 carries a dredge 15 whee-L assembly indicated generally at 19 and later described more particularly with reference to FIGS. 2 , 3 and 4 of the drawings.• Material excavated by the dredge wheel is received in. a suction duct 20 which is carried back along the ladder frame 11 to a pump (not 20 shown) driven by a dredge engine (not shown) within the engine room 21 o£ the dredge, the pump discharge being connected to an outlet conduit 22 which is connected in turn to a floating or pontoon-supported conduit (not shown) leading to the shore- The engine also operates 25 the hydraulic system of the dredge.

For slewing the dredge, a pair of cables 23 from anchors (not shown) dropped to both sides of the front of the dredge are carried through a pair of counter¬ balanced sheave blocks 24 on the ladder frame and thence 30 to a pair of winches 25 on the rear part of the ladder frame.

Referring now particularly to FIGS. 2 and 3 of the drawings, the dredge wheel assembly 19 includes a housing 26 for a hydraulic motor and gearbox (not shown)

35. driving a cylindrical dredge wheel hub 27. Radiating

O PI Radiating from the hub 27 are two axially spaced series of cutter arms 28, of elongated rectangular cross-section, those of each series being staggered relative to those of the other so that all the cutter arms of the two series are in equiangularly spaced relationship. The cutter arms 28 are pitched, each being set at an acute angle to a plane perpendicular to the axis of the hub 27, the cutter arms of the two series being oppositely pitched so that, when the dredhe wheel is rotated under water, in the direction indicated by arrows in FIGS. 1 and 2, the cutter arms tend _.to impel the water inwardly from both sides towards the middle of the dredge wheel.

To the outer- end of each cutter arm there is secured a forwardly extending cutting tip 29, substantially tangential to a circle centred on the axis of the hub 27; and to each cutter arm there are secured blades or teeth 30 extending from the front or leading edge of the cutter- arm. The suction duct 20. is connected to and leads from an intake chamber- 31, mounted under the front of the ladder- frame 11 so that the front opening or mouth 32 of the intake chamber is located close under the dredge wheel hub 27 and between the two series of cutter arms 28. An upright breaker plate 33 is mounted centrally in the mouth 32 of the intake chamber 31.

In use, as the dredge is worked, the dredge wheel is rotated in the direction indicated by arrows in FIGS. 1 and 2, which is the direction opposite to that of a conventional bucket wheel or dredge wheel fitted with a peripheral series of excavating buckets. According to the invention, the dredge wheel excavates on the downward and rearward parts of its travel, the cutter arms 28 moving down and back through sea-bed material to be dredged and indicated at 34 in FIG. 1. The pitched

OMFI - cutter arms urge the excavated material inwardly from both sides, and thus into the mouth 32 of the intake chamber 31, from which it is drawn through the suction duct 20. The dredge wheel rotated in this manner urges the dredge to move forwards, and no spudd¬ ing arrangement will be required for this purpose, so that considerable costs in manufacture and operation of the dredge will be obviated. The rate at which the dredge draws itself forward is regulated by a tail cable 35 carried from any suitable anchorage to a sheave block 36, and submerged to avoid being fouled by the floating conduit, and then, through appropriate sheaves, to a winch 37. By paying-off cable from this winch, the dredge is permitted to advance at the required rate. Referring now to FIG. 4 of the drawings, the dredge wheel 19 of this embodiment is of bucket-wheel type, having a cylindrical hub 38 with a series of equally spaced similar buckets 39 mounted about its periphery. Each of the buckets is in the form of a scoop with an open mouth 40 and a, closed back 41, the interior of the bucket leading to the interior of the hub 38 which communicates with the forward end of an intake chamber 42 leading to the suction duct 20. The dredge wheel is rotated by the means, and in the direction, before described. The material excavated by and received in the buckets travels generally downwards,and for a short distance, before entering the suction duct whereas, in a conventional bucket wheel, rotated in the opposite direction, the buckets must lift the material excavated and convey it through a greater arc to the suction duct. Dredges according to the invention will be found to be very effective in achieving the objects for which they have been devised.- It will, of course, be under¬ stood that the particular embodiments of the invention herein described and illustrated may be subject to many modifications of constructional detail and design, which will be readily apparent to persons skilled in the art, without departing from the ambit of the invention hereinafter claimed.

Claims

1. A dredge of the type having a hull, a frame mounted on the hull and having mounted at its front a motor-driven rotatable dredge wheel with a series of excavating members extending from its hub, means for lowering or raising the frame and the dredge wheel thereon, and a suction duct on the frame to receive and convey material excavated by the dredge wheel, wherein: the dredhe wheel is rotated in the direction to cause its excavating members to excavate while moving downwardly in front of, and rearwardly below, the hub.

2. A dredge according to Claim 1 wherein: the excavating members include two series of cutter arms radiating from the dredge wheel hub, the two series being spaced axially in relation to the ^"hub, the cutter arms of the two series being pitched oppositely so- that, during excavation, the excavated material is urged from both sides of the dredge wheel inwardly between the two series of cutter arms.

3. A dredge according¹ to Claim 2 wherein: the suction duct leads rearwardly from an intake chamber having at its front a mouth located close to the lower part of the dredge wheel hub.

4. A dredge according to Claim 3 wherein the mouth of the intake chamber is between the two series of cutter arms.

5. A dredge according to Claim 3 wherein the cutter arms enter the intake chamber by way of its mouth during the rearward part of their travel and leave the intake chamber by way of openings in its top during the upward part of their travel.

6. A dredge according to any one- of Claims 2 to 5 wherein each of the cutter arms has projecting from the leading edge of its distal end a cutting tip.

7. A dredge according to Claim 1 wherein: the excavating members include a series of dredge buckets mounted peripherally in equally spaced arrangement about the dredge wheel hub and lead to the interior of the hub, and the suction duct leads rearwardly from the hub interior.

8. A dredge substantially as herein described with reference to FIGS. 1, 2 and 3 of the accompanying drawings.

9. A dredge substantially as herein described with reference to FIGS. 1 and 4 of the accompanying drawings.

OMPI