Title:
PROPELLING MEANS FOR A DREDGE
United States Patent 3656449


Abstract:
The propelling means comprises two vertically slidable spuds mounted on the stern of a dredge. One of the spuds is a holding spud and is used to prevent drifting of the dredge when the other spud is being manipulated to propel the dredge forwardly. The other spud is a working spud and is used as an anchoring pivot point when imbedded in the bottom of a body of water to permit taking a cut. The working spud is disengaged from the bottom of a body of water after a cut has been taken and is shifted towards the stern of the dredge. It is then re-imbedded in the bottom of the body of water whereupon the holding spud is removed. Power means then cause the dredge to be propelled forwardly, pushing off from the working spud.



Inventors:
MEAD HERBERT W
Application Number:
05/042311
Publication Date:
04/18/1972
Filing Date:
06/01/1970
Assignee:
HERBERT W. MEAD
Primary Class:
Other Classes:
37/346
International Classes:
E02F9/06; (IPC1-7): B63B21/56; B63H15/00
Field of Search:
115/9 37
View Patent Images:
US Patent References:
1792065Dredge1931-02-10Bowers
0743751N/A1903-11-10



Foreign References:
NL23582A
Primary Examiner:
Blix, Trygve M.
Claims:
I claim

1. Propelling means for a dredge which includes a hull having a cutter extending forwardly from the bow, said propelling means comprising a pair of upright spuds vertically slidably mounted at the stern, said spuds being mounted on said hull independently of one another, one of said spuds being a working spud and the other of said spuds being a holding spud, said working spud being located on substantially the center line of the hull and said holding spud being spaced from the center line, means to raise and lower each spud into and out of an imbedded position on the bottom of a body of water, said working spud, when imbedded in the bottom of a body of water, serving as leverage for propelling the dredge forwardly and as a pivot point for pivoting of the hull to move the cutter in an arc, said holding spud, when embedded in the bottom of a body of water with the working spud not imbedded in the bottom, serving as an anchor to prevent drifting of the dredge, mechanical means for movably connecting the working spud to the hull, said mechanical means comprising a spud holder frame structure and linkage, said linkage being pivotally connected at one end to the hull and being pivotally connected at the other end to said spud holder frame structure, guide means on said frame structure slidably receiving and supporting said working spud, and power means mounted on the hull connected to said mechanical means operative to shift said mechanical means to move the working spud to a position adjacent the hull when the working spud is not imbedded in the bottom and, after the working spud has been imbedded in the bottom after being so moved, to move the hull forwardly with the working spud serving as leverage.

2. Propelling means as defined in claim 1, further characterized in that said linkage comprises vertically spaced apart upper and lower arms each pivotally connected at one end to the hull and at the other end to said frame structure, said power means comprising a double-acting power cylinder having a reciprocal rod pivotally connected at its outer end to the upper arm.

3. Propelling means as defined in claim 2, further characterized in that said power cylinder is pivotally attached to the hull.

4. Propelling means for a dredge which includes a hull having a cutter extending forwardly from the bow, said propelling means comprising a pair of upright spuds vertically slidably mounted at the stern, said spuds being mounted on said hull independently of one another, one of said spuds being a working spud and the other of said spuds being a holding spud, said working spud being located on substantially the center line of the hull and said holding spud being spaced from the center line, means to raise and lower each spud into and out of an imbedded position on the bottom of a body of water, said working spud, when imbedded in the bottom of a body of water, serving as leverage for propelling the dredge forwardly and as a pivot point for pivoting of the hull to move the cutter in an arc, said holding spud, when imbedded in the bottom of a body of water with the working spud not imbedded in the bottom, serving as an anchor to prevent drifting of the dredge, mechanical means for movably connecting said working spud to the hull, said mechanical means comprising a spud holder frame structure and a pair of vertically spaced apart arm structures, each of said arm structures including a pair of laterally spaced arms, each arm being pivotally connected at one end to said hull and at the other end to said spud holder frame structure, guide means on said frame structure slidably receiving and supporting said working spud, and power means mounted on the hull connected to said mechanical means operative to shift said mechanical means to move the working spud to a position adjacent the hull when the working spud is not imbedded in the bottom and, after the working spud has been imbedded in the bottom after being so moved, to move the hull forwardly with the working spud serving as leverage.

5. Propelling means as defined in claim 4 wherein the arms of each of said arm structures have forwardly extending portions, intermediate diverging portions and rearwardly extending portions, with the forwardly and rearwardly extending portions of each of said arm structures being parallel, said forwardly extending portions of each of said arm structures being connected by a reinforcing plate.

6. Propelling means as defined in claim 5 wherein a single pivot pin extends through the ends of the forwardly extending portion of each of said arm structures to pivotally connect same to said spud holder frame structure.

7. Propelling means as defined in claim 5 wherein a single pivot pin extends through the end of each of the rearwardly extending portions of each of the arm structures to pivotally connect same to the hull.

8. Propelling means as defined in claim 5 wherein said power means comprises a double-acting power cylinder pivotally attached to the hull and having a reciprocal rod pivotally connected at its outer end to the upper one of said arm structures.

Description:
BACKGROUND OF THE INVENTION

Dredges are commonly used, and have been for a considerable length of time, to remove material from the bottom of a body of water to deepen channels and the like to permit, for example, passage of ships having deep draft. Commonly, a pair of vertically slidable spuds have been provided at the stern of such dredges for anchoring the dredges and for stepping the dredges forwardly after each cut has been taken by means of a rotary forwardly extending cutter provided at the bow of the dredge. Such spuds have been located at the stern of the dredge offset from the center line of the dredge, toward the sides thereof. In operation, one of the spuds has been lowered into imbedment with the bottom of a body of water while the other spud is lifted out of engagement with the bottom of the body of water. The imbedded spud has served as an anchor and as a pivot point for pivoting of the dredge whereupon the cutter cuts along an arc with a center defined by the imbedded spud.

At the end of the arc, the dredge is at an angle to its initial position and the unused spud is consequently positioned forwardly of the spud which has served as the anchor and pivot point. At this time, the spud which was not used initially is dropped into the water and imbedded in the bottom. The other spud is then lifted out of engagement and the dredge is pivoted in the opposite direction taking a new cut. The geometry of this type of operation results in the arc taken in one direction not being parallel to the arc taken in the other direction with the consequence that the arcs overlap at some points resulting in over-cutting and diverge in other areas resulting in under-cutting in such areas. The consequence is that the dredging action is not as satisfactory as would be desired.

In accordance with the present invention, a pair of spuds is also used. However, only one of the spuds, which is located at the centerline of the dredge, is used as the pivot point for the dredge. The other spud is used only to anchor the dredge in place when the first spud is being manipulated to propel the dredge forwardly. The result is that the cuts taken by the dredge are uniform and are parallel to each other thus providing a uniform dredging action across the entire bottom of the body of water with no portion being overcut or undercut.

SUMMARY OF THE INVENTION

Propelling means and a method for dredging are provided. The propelling means are mounted on a dredge which includes the usual hull having a cutter extending forwardly of the bow. The propelling means comprise a pair of upright spuds which are vertically slidably mounted at the stern of the dredge. One of the spuds is a working spud and the other spud is a holding spud. Means are provided to raise and lower each spud into and out of an imbedded position on the bottom of a body of water. Movable structure connects the working spud to the hull. Power means are provided on the hull connected to the movable structure. The power means are operative to move the working spud to a position adjacent the hull when the working spud is not imbedded in the bottom and, after the working spud has been imbedded in the bottom after being so moved, to move the hull forwardly with the working spud serving as leverage. The holding spud is imbedded in the bottom of the body of water to anchor the dredge during periods when the working spud is not imbedded in the bottom of the body of water.

IN THE DRAWINGS:

FIG. 1 is a side elevational view of a dredge employing the propelling means forming one embodiment of the present invention;

FIG. 2 is a plan view of the dredge of FIG. 1;

FIG. 3 is an enlarged view of the propelling means; and

FIG. 4 is a sectional view of the propelling means taken substantially along the line 4--4 of FIG. 3 looking in the direction of the arrows.

The dredge 10 is in many respects relatively conventional. The dredge 10 comprises a hull 12 which will float on water or mud. A slot 14 is provided in the bow of the hull 12. A conventional ladder 16 is positioned in the slot 14 and is pivotally mounted at 18 to the hull. The ladder 16 swings vertically in the slot 14 in the usual manner. The ladder 16 carries a rotary cutter 20 driven by a shaft 22 to which power is applied by a motor (not shown). The ladder 16 is raised and lowered by a derrick 24. A deckhouse 26, including an operating room 28, is provided on the hull 12. The operating room 28 includes the control mechanisms for actuating the various structures of the dredge.

Propelling means 30 are provided on the stern of the hull 12 for moving the dredge 10 forwardly during the dredging action. The propelling means 30 includes a pair of vertically disposed spuds 32, 34. One of the spuds 32 is referred to as the working spud and is employed to propel the dredge forwardly. The other spud 34 is termed a holding spud and functions as an anchor to hold the dredge 10 in place during manipulation of the spud 32.

The holding spud 34 is located sidewardly of the center line of the hull 12. The spud 34 is supported and guided in a pair of vertically spaced apart guide structures 36, 38 which are secured to the stern of the hull 12. A motor driven winch 40 is provided on the deck of the dredge adjacent the spud 34. A cable 39 extends from the winch 40 over a pulley 42 and downwardly through a guide tube 44 into connection with a bracket 46 provided adjacent the lower end of the spud 34. The spud 34 is raised by actuation of the winch 40. The spud is lowered by means of gravity.

The working spud 32 is supported and guided in a pair of vertically spaced apart guide structures 48, 50 which are secured to a spud holder frame 52. A motor-driven winch 54 is provided on the deck of the dredge adjacent the stern thereof. A cable 56 extends from the winch 54 over a pulley 58 mounted on the upper end of the frame 52 and downwardly through a guide tube 60 provided on the frame 52. The lower end of the cable 56 is connected to a bracket 62 provided adjacent the lower end of the spud 32. The spud 32 is raised by actuation of the winch 54. This spud is lowered by means of gravity.

The frame 52 is pivotally supported on the dredge by means of a pair of vertically spaced apart arm structures 64, 66. As will be noted in FIG. 4, each of the arm structures includes a pair of arms having forwardly extending portions 72, 78 which are closely adjacent each other and reinforced by means of a plate 80. A sleeve 82 extends through openings in the forward ends of the portions 72, 78 The sleeve 82 is received between vertically extending walls 84, 86 of the frame and is placed in alignment with openings in these walls. Each wall carries a boss 88, 90. A pin 92 extends therethrough to pivotally attach the arm structure to the frame.

Each arm has diverging portions 94, 96 extending generally towards the stern 98. A reinforcing plate 100 extends between portions 94, 96 and is welded in place. Straight arm portions 102, 104 extend from the ends of the portions 94, 96. The portions 102, 104 are pivotally connected to brackets 106, 108 which are secured to the stern 98. As will be noted in FIG. 3, recessed portions 110, 112 are provided in the frame 52 to receive portions of the arms when the arm structures are pivoted upwardly and downwardly.

An hydraulic power cylinder 114 is provided as the motive propelling force. The cylinder 114 is pivotally connected at its rearward end to a bracket 116 secured to the deck. A piston rod 118 extends from the cylinder 114 into pivotal connection with a bracket 120 which is secured to the reinforcing plate 80 of the upper arm structure 64. The cylinder 114 is a double-acting cylinder so that the piston rod 118 may be powered to either be extended or retracted. Upon retraction of the rod 118, as viewed in FIG. 3, the arm structures 64, 66 are caused to pivot upwardly and carry the frame 52 to a position adjacent the stern 98 as indicated in dotted lines. Extension of the rod 118, with the spud 32 imbedded in the bottom 122 of the area being dredged, results in propulsion of the dredge 10 forwardly. The dredge is propelled in normal steps of about 30 inches. However, the amount which the dredge is propelled any given time may be varied by varying the stroke of the rod 118. The rod stroke may be controlled by suitable valve means.

As will be noted in FIG. 4, the center line of the cylinder 114, arm structures 64, 66 and spud 32 lie on the center line 124 of the dredge. Consequently, when the dredge is propelled by means of the spud 32, it will be moved straightforwardly along a line defined by the center line 124.

Operation of the dredge 10 may now be understood. Referring first to FIG. 2, the dredge 10 may first be set in a position as indicated by dotted lines. Assuming that it is wished to advance the dredge for making a cut, the holding spud 34 is lowered into engagement with the bottom and the working spud 32 is raised out of engagement with the bottom. The holding spud will maintain the dredge in the desired position. The power cylinder 114 is then actuated to cause the arm structures 64, 66 to raise and move the frame 52 and working spud 32 to the position illustrated in dotted lines in FIG. 3. The working spud 32 is then lowered into engagement with the bottom. The holding spud 34 is then raised out of engagement with the bottom. The power cylinder 114 is then actuated to extend the rod 118 and cause the dredge 10 to advance along the lines 126, 128 which coincide with the center line of the dredge. After the dredge has been moved forwardly, the cutter 20 is actuated and the ladder 16 swings in the direction of arrows 128 along a segment of a circle the center of which is the spud 32. At the opposite end of the cut, the spuds 32, 34 are again manipulated to move the dredge forwardly in the direction of the lines 130, 132 whereupon the cutter is again operated and the ladder is swung in the reverse direction along an arc defined by the arrows 134.

As will be appreciated from the operation thus described, the cutter is caused to travel along arcs of a circle which are parallel. Thus, there is no overlapping of the cutting so that the same area is not operated upon in a fashion to result in over-cutting. Nor is any area which should be acted upon missed because there is no area which is bypassed by the parallel cutting arcs. The amount of the bottom acted upon is determined by the physical dimensions of the cutter and the nature of the material acted upon. The degree of forward movement after each cut may be varied by varying the stroke of the cylinder 114 to assure proper cutting action regardless of the conditions under which the dredge is operated.