US3476498A

US3476498A - Bucket-wheel cutter for dredges

Info

Publication number: US3476498A
Application number: US601694A
Authority: US
Inventors: Edgar J Von Bolhar
Original assignee: Ellicott Machine Corp
Current assignee: Ellicott Machine Corp
Priority date: 1966-12-14
Filing date: 1966-12-14
Publication date: 1969-11-04
Anticipated expiration: 1986-11-04
Also published as: NL6714608A

Description

NOV- 4, 1969 E. J. voN BOLHAR 3,476,498

BUCKET-WHEEL CUTTER FOR DREDGES Filed Deo. 14, 1966 3 Sheets-Sheet l N0V- 4, 1969 E. J. voN BOLHAR BUCKET-WHEEL CUTTER FOR DREDGES 3 Sheets-Sheet Filed Dec. 14. 1966 N0V 4, 1969 E. J. VON BOLHAR BUCKET-WHEEL CUTTER FOR DREDGES 3 Sheets-Sheet I5 Filed Dec. 14, 19466 JN VEA/T01? 5064,? J l/o/u 50044@ United States Patent O 3,476,498 BUCKET-WHEEL CUTTER FOR DREDGES Edgar J. von Bolhar, Severna Park, Md., assignor to Ellicott Machine Corporation, Baltimore, Md., a corporation of Maryland Filed Dec. 14, 1966, Ser. No. 601,694 Int. Cl. E02f 3/24, 3/ 92, 7/00 ABSTRACT 'oF THE DISCLOSURE with one perforated wall arrangedlrelative to the olw of material through Vthesuction mouth so as to receive and retain the denser objects loosened by the digging wheel.

This invention generally relates to dredges and more particularly to suction dredges employing a rotary digging wheel to loosen the material being dredged.

The environment of the present invention is in hydraulic dredges of the type wherein the material being dredged is` loosenedzby a rotary digging means and channeled to the entrance mouth of a suction pipe. From the rotary digging means, water and the material being dredged tare drawn through the suction pipe by a centrifugal dredge pump and discharged into a discharge pipe through which the dredged material is conducted to an appropriate disposal or storage point. 'Ihe dredge of the present invention operates in the usual manner lby swinging the dredge through an arc of approximately 90 to urge the digging means into engagement with the material being dredged.

It is among the objects of the present invention to provide` an improved rotary digging wheel for a dredge..

It is an importantobject of this invention to provide a rotary digging wheel which digs on both the port and starboard swingof Vthe dredge. `l

It is another object of this invention to provide a novel bucket cleaning apparatus which functions as4 the digging wheel rotates. i

It is a further object of the present invention to provide a rotary digging wheel dredge which is suitable for use in placer mining operations.

Further objects and advantages of this invention will appear from the following detailed description and th appended drawing wherein: y t In the drawing: v

FIGURE 1 illustrates a dredge apparatus embodying in an overall efficiency for the dredge of somewhere bethe present invention; p FIGURE 2 is a partial s'ide elevation of the dredge ladder and digging wheel embodied in the present invention; t

FIGURE 3 is a side elevation of the digging wheel illustrated in FIGURE 2;

FIGURE 4 is a cross sectional view of the digging wheel taken along line 4-4 of FIGURE 3;

FIGURE 5 is a schematic illustration of a digging wheel incorporating a mud-scraper for `the buckets; and,

FIGURE 6 is a schematic illustration of the internal portion of the digging wheel.

Referring to the drawing, FIGURE 1 illustrates a dredge, generally indicated at 10, including a hull`12, a deckhouse 14 atop which is a pilot house or dredge oper- 3,476,498 Patented Nov. 4 1969 ice ators compartment 15. From the deckhouse 14 two portions 11 and 13 of the hull 12 extend forwardly on both sides of the dredge to form a ladder well 17 within which is disposed a cable controlled ladder assembly 16. The ladder assembly 16 includes a pair of spaced apart ladder sections 19Aand 21 pivoted to the hull 12 adjacent their inner ends about a horizontal axis 18.

On the outer free end of the ladder assembly 16 is a rotary digging wheel, indicated generally at 20, about the circumference of which are disposed a plurality of digging means in the form of buckets or scoops 22. The digging wheel 20 is gear driven through a reduction unit 24 by a pair' of hydraulic motors 25, preferably of the radial cylinder, low speed type. The material being dredged is loosened by the buckets 22 and drawn through a suction pipe 27 by a centrifugal dredge pump 28 located within the deckhouse 14 or within a watertight capsule mounted on the ladder assembly 16. From the dredge pump, the loosened material is conducted through a discharge pipe 29 to an appropriate disposal or storage point.

The dredge is operated in the usual manner by swinging the dredge and ladder assembly in an arc to urge the digging wheel 20 into the material to be dredged, with the length of the arc corresponding to the width of the cut. The depth of the cut is controlled by either raising or lowering the ladder assembly 16 by a winch (not shown) in the deckhouse 14 connected to the outer free end of the ladder assembly 16 through a hoist cable 31 and pulley block arrangement 32 supported from an A- frame 33.

Swinging movement of the dredge 10 and the digging wheel 20 is controlled by alternately winding in and paying out port and starboard

swing anchor lines

35 and 36, respectively. The

swing anchor lines

35 and 36 extend from Iwinches (not shown) located within the deckhouse 14 along the ladder assembly 16 and around pulleys on the outer end of the ladder assembly 16, such as the starboard swing anchor pulley 38, to swing anchors (not shown) in the water olf to the sides and in front of the dredge. The dredge 10 alternately pivots about either one or the other of a pair of port and starboard spuds 39 and 40 respectively as the ladder and front end portion of the dredge swing through an arc. The dredge is moved forward by 4alternately raising and lowering the port and starboard spuds 39 and 40 upon completion of a cut.

With theusual rotary cutter `means employed on suction dredges a dredging cut can be made in only one direction and upon completion of the cut the cutter assembly must be swung back to the starting position to begin the next Cut. While the return swing can be made at a higher speed than the dredging cut, the return swing is a nonpro-ductive time consuming operation which significantly reduces'the `eiliciency of the dredging operation. With a digging wheel constructed in accordance with the present invention, a dredging cut can be made in both directions. This improvement increases the productivity and results tween 30 to 50 percent so-lids.

Referring to FIGURES 3 and 4, the illustrated digging wheel 20, includes a rotating rim section 42 and a stationary hub housing section 44. The rotating rim section 42 comprises a pair of spaced rim or

side plates

46 and 47 between which the circumferentially spaced buckets or scoops 22 are rigidly secured. Rim plate 46 is rigidly secured at 48 to a shaft 49 extending transversely of the ladder `sections 19 and 21 and driven by the hydraulic motors 25 through gears `50 and 51 of 'the gear reduction unit 24. The gear reduction unit 24 is preferably filled with oil and pressurized to a pressure about 5 p.s.i. above that of the surrounding water at the dredging depth to prevent contamination of the oil by the surrounding water.

Each of the buckets 22 includes a bowl portion 55 having a curved blade-like bottom wall 54 anda cutting portion comprising a symmetrical ared lip 53 about the inlet opening to the bowl 55 for loosening the material being dredged. The symmetrical cutting lip 53 enables the buckets 22 to make a digging cut when the wheel is moved in either lateral direction perpendicular to its plane of rotation. The radial inner portion of the bowl 55 is open allowing the loosened material to pass `betweenthe

rim plates

46 and 47 into the stationary hub section 44 of -the digging wheel. 7

The stationary hub section 44 is shown schematically in FIGURE 6 and includes a pair of laterally spaced

plates

56 and 57 carrying a bearing assembly 61 within which if.

the shaft `49 is rotatably journalled. The

plates

56 and 57 together with a pair of laterally extending walls 58 andf59 define a re-entrant suction mouth or box 60 into which the loosened material passes from the buckets 22. The suction pipe 27 is connected to the suction mouth 60 through a circular to rectangular transition section 65 coming off of the plate 57 on the hub section at an angle of approximately-21. A j f The hub section 44 also includes a mould plate 68 extending partially around the circumference of the hub section adjacent an arc prescribed by the inner ends of the rotating buckets 22 on the rim section 42. The mould plate 68 forms a temporary bottom for the open inner ends of the buckets 22. An opening 69 through the mould plate 68 allows the loosened material to be washed from the buckets 22 into the suction mouth 60` by the surrounding water.

The illustrated digging Wheel operates rnost effectively when used to dredge relatively loose material such as sand or gravel, for once the lip 53 loosens the material, the surrounding water washes many times the volumetric capacity of the bucket 22 through the bucket into the suction mouth 60 before that bucket rotates clear of the material being dredged. When operating in sand and gravel relatively large objects such as rocks may be swept through the buckets 22 into the suction mouth 60. To keep out the largest of these rocks a coarse grate formed by one or more grizzly bars 63 may be provided to narrow the opening `69 as shown in FIG. 6. Those rocks which enter the suction mouth 60 and which are too big to pass into the suction pipe 27 become wedged in the transition section 65 and are removed from the digging wheel by removing a clean out plate 72 over an opening in the wall of the transition section. When the suction mouth becomes clogged with rocks, the digging wheel is stopped and raised out of the water whereupon a workman opens the clean out plate 72 and reaches in through the opening to remove the rocks wedged in the transition section 65.

When the digging wheel is used for the placer mining of gold bearing gravel deposits, a chamber 74 is provided in the lower portion of the stationary hub section 44 to serve as a nugget collection box. The chamber 74 is separated from the suction mouth 60` by a perforated portion 75 in the bottom Wall 59 of the suction mouth. The perl forated portion 75 comprises a plurality of openings 76 through the wall 59 as shown in the exploded portion of FIGURE 6. The perforated portion 75 is so positioned relative to the flow of material through the suction mouth 60 toward the suction pipe entrance 65 that the inertia of the heavier objects will cause them to strike the perforated portion. If the object is a relatively small but dense one such as a gold nugget it will pass through an opening 76 into the nugget collection box 74. Although other small particles of the loosened material may also pass through these openings the swirling action in the chamber 74 caused by the rush of Water through the suction mouth 60 will be suflcient to carry them lback up into the suction mouth where they will be washed out through the suction pipe 27. However, this swirling action is not strong enough to prevent the denser gold nuggets from settling to the bottom of the collection box 74 where they will remain until they can be conveniently removed by removing a 'side clean out plate 77 on the digging wheel. When dredging sand and gravel deposits lenses or at pockets of clay and mud are often encountered. Sometimes, before the buckets are actually packed full of mud, balls of mudform and tumble about in the turbulent water in the suction mouth, then shoot'up through the suction pipe 27 and accumulate at the entrance to the centrifugal dredge pump 28. There is 'no diieulty in forcing these mud bfalls throughthe pump 28l and out throughthe discharge pipe 29 Lwhen'thebucketss 221emain open to admit sufficient water to wash them through. However, when the buckets become packed with mud there is anainsuicient., supply of/water to wash the mud through the dredge pump and it becomes clogged stopping the dredging operation.

FIGURE 5l schematically illustrates an apparatus 80 for scraping the mud from the buckets 22. The scraper apparatus includes a retractable blade 82 slidably mounted in a pair of tracks 83 on the hub 44 and a spring means to bias the outer end of the blade 82 into the path of the rotating buckets 22. In the projected position its outer end engages the curved bottom wall 54 of each bucket i' bowl 55 and scrapes the mud therefrom vas the bucket rotates past. The curved wall 54 also cams theblade 82 radially inwardly. to its' fully retracted position so that it will spring radially outwardly into the succeeding bucket.

In order to produce the effect of a single long spring in the limited space available within the hub portion 44 of the digging wheel 20, the biasing means for the scraper blade 82 comprises a pair of coil-

like springs

85 and 87 housed in a pair of

cylindrical spring capsules

84 and 86 connected together by a lever arm 91. The lever arm '91 is centrally pivotedY to the stationary section44 at 92 with its ends being pivotally. connected to the left ends of the capsules 84and 86 at93 and 94 respectively. The Vright end of capsule 86 is pivotally secured to the stationary section 44 at 90 while the right end of the spring capsule 84 is pivotally connected at 89 to the blade 82. The extent of the blades projection beyond the mould plate 68 is limited by a stop 96 on the hub 44 which is engaged by the end of the lever arm 91 during the outward travel of the blade.

In normal dredging operation the scraper blade 82 is maintained in a retracted position in which its forward end is substantially ush with a mould plate 68. An

\' actuator 97 is provided to overcome the

springs

85 and 87 to hold the blade 82 in such retracted position. Invthe event the buckets 22 become clogged the pump vacuum increases and gives the operator an indication of the clogged condition. The operator then raises the digging wheel clear of the bottom and slows the wheel down so that the scraper can operate properly. The actuator 97 is then retracted to allow the scraper to operate.

What is claimed is:

1. A dredge cutter comprising a hub housing, a cutter wheel mounted for rotation about said hub housing,

curved blades mounted circumferentially about said cutter wheel, said hub housing having a suction mouth adapted to be connected to dredge suction apparatus, said suction mouth terminating at the periphery of said hub housing on an arc described by the inner ends of said curved blades in their travel about said hub housing, scraper means mounted on said hub housing, said scraper means including a retractable scraper blade biased to project radially from said hub housing and into the rotary path of said curved blades upon rotation of said cutter wheel about said hub housing whereby rotational movement of said cutter wheel on said hub housing causes each curved blade to overcome the bias of said scraper blade andl move itfradially inward into the housing and at the same time scrape material being dug from said curved blade into said hub housing, said scraper means including scraper blade biasing means for said retractable scraper blade comprising a pair of springs interconnected by a pivoted lever, one end of one of said springs being xed relative to said hub housing and one end of the other of said springs engaging said scraper blade.

2. A dredge cutter according to claim 1 wherein said scraper means includes stop means interacting between said hub housing and said scraper means to limit the outward movement of said retractable blade.

3. A dredge cutter as set forth in claim 2, wherein a portion of said pivoted lever of said scraper blade biasing means engages said stop means to limit the movement of said retractable scraper blade.

4. A dredge cutter as set forth in claim 1, wherein said curved blade forms a wall of a bucket.

5. A dredge cutter as set forth in claim 1, wherein power operated retraction means are provided to overcome the bias of said springs and to cause retraction of said scraper blade, said spring means normally biasing said retractable scraper blade outwardly from said hub housing.

6. A dredge cutter as set forth in claim 1, wherein said suction mouth assembly has a substantially rectangular outer mouth portion at the outer periphery of said hub, said suction mouth having a lower edge opening at said periphery below the axis rotation of said cutter wheel, said suction mouth having its upper edge opening at said periphery above the axis of rotation of said cutter wheel, said upper edge and said lower edge being circumferentially spaced a distance greater than the circumferential distance from one of said curved blades to the next circumferentially adjacent of said curved blades, said suction mouth being adapted to receive a suction pipe at a junction point entirely below the axis of rotation of said cutter wheel.

7. A dredge cutter according to claim 6, wherein said suction mouth has a collecting chamber below the junction with said suction pipe, said chamber being separated from said suction apparatus by a perforated portion in the bottom wall of the said suction mouth, said perforated portion being positioned relative to the fiow of material through said suction mouth towards said suction pipe that the relative density of heavier dredged particles will cause them to strike the perforated portion, said perforated portion permitting relatively small but dense particles to pass into said chamber and be collected therein.

8. A dredge comprising a hull including forward por tions along each side of the hull to provide a well for a dredge ladder, a dredge ladder pivotally mounted on the hull for raising and lowering within the ladder well, said dredge ladder comprising spaced elongated ladder sections, a rotatable shaft extending transversely between said ladder sections at the outer end thereof, a rotatable bucket wheel secured to said shaft for rotation therewith, said bucket wheel having spaced side plate members to form a passage between said side plate members, a series of digging buckets xed to said side plate members, one of said plate members having `a circular opening, said digging buckets having U-shaped lips forming the mouths of said buckets and said lips aring outwardly beyond said side plates, said digging buckets being open towards the center of said bucket wheel, a suction box mounted within said bucket wheel between the planes of said side plates, said suction box being part of a non-rotating hub, supported by said shaft, said suction box opening adjacent to the inside of said bucket wheel so as to receive all of the dredged material coming through the open side of the digging buckets and said passage between said side plates, a suction pipe having one end thereof connected to said suction box, a suction pump mounted on the dredge and said suction pipe terminating at the inlet of said suction pump, hydraulic motor means carried by said dredge ladder adjacent said bucket wheel, and gearing connecting said hydraulic motor to said shaft to rotate the bucket wheel and discharge dredged material into said suction box, said non-rotating hub being adapted to permit axial movement on said shaft through the said circular opening in said one of said side plates.

9. A dredge cutter comprising ya cutter wheel having a stationary hub suction and a rotating rim section fixed to a shaft, said rim section carrying curved blades mounted for rotation about said hub section, said hub section defining a re-entrant suction mouth connected to a dredge pump, said suction mouth terminating at the periphery of said hub section adjacent an arc prescribed by the inner ends of said curved blades in their travel about said hub section whereby the material being scooped up by said curved blades is sucked from said suction mouth into a suction pipe connected thereto by said dredge pump, said hub section having therein a chamber below said shaft and said suction pipe and being separated from said suction mouth by a perforated plate having a plurality of small apertures said perforated plate being so arranged in said suction -mouth that relatively small but denser particles being dredged into :said suction mouth will have a tendency to strike it and pass through the openings therethrough into said chamber and be collected therein and removed from time to time.

References Cited UNITED STATES PATENTS 25,875 10/ 1859 Barcroft.

`216,061 6/ 1879 Shaw 37-58 388,252 8/1888 Bowers 37-66 813,252 2/ 1906- Strom 37-66 2,616,560 11/1952' Vogelpoel 209-17 2,722,759 11/ 1955 Cosenza 37--66 2,731,741 1/ 1956 Kaufmann 37--54 2,732,641 1/1956 Jespersen 37-189 2,826,839 3/ 1958 Kolbe 37-190 FOREIGN PATENTS 57,081 3/1946 Netherlands.

ROBERT E. PULFREY, Primary Examiner C. D. CROWDER, Assistant Examiner U.S. Cl. X.R.