US2039944A - Method of and device for deep sea dredging - Google Patents

Description

May 5, 1936. J. c. WILLIAMS METHOD OF AND DEVICE FOR DEEP SEA DREDGING Filed March 28, 1934 2 Sheets-Sheet l INVENTOR.

l mi A TORNE YS.

y 6-' J. c. WILLIAMS 2,039,944

METHOD OF AND DEVICE FOR DEEP SEA DREDGING Filed March 28, 1934 2 Sheets-Sheet 2 INVENTOR. 34 3/ 25 Y 4, a M

Patented May 5, 1936 UNITED STATES PATENT OFFICE METHOD OF AND DEVICE FOR DEEP SEA -DREDGING 7 24 Claims.

This invention is a deep-sea dredge for dredging at great depths under high hydrostatic pressure where present types of dredges and excavators cannot successfully be used.

In deep sea dredging, it is impractical to use any type of rigid or torsion resistant raising and lowering means for the dredge, the only practical solution of this problem being in the provision of a self-contained unit which is complete in all details as to both, mechanical and driving equipment, and which unit is raised and lowered by flexible means such as a cable or chain through the medium of a winch or hoist mounted on a ship or float above the surface of the water, the dredge being electrically controlled from the surface, merely requiring the operation of a switch for starting and stopping the dredge operating motors.

In all cases where deep-sea dredging has. been tried, the chief difficulty encountered has been in the sealing of the enclosure for the motors, especially about protruding shafts, against the high hydrostatic pressures, since with the usual meth- .ods of packing, all lubricant is forced out of the into the enclosure, thus counterfiting the pres-; sure urging ingress by the same pressure applied to the lubricant at a point remote from the point of attempted ingress.

Another feature which has caused previous experiments in deep-sea dredging to fail is the fact that no practical solution of the problem of preventing rotation of the sludge receiver when the dredge is operated has been discovered. This problem has been overcome in my invention through the agency of a spud which operates in advance of the cutter head and anchors the recelver against rotation on its own axis.

Values of various descriptions are found in the sea bottom, an example of which is the gold dust" beds in Alaska, where a high grade sludge forms the bottom of the sea over an extensive area and contains gold dust running in value from nine to forty-five dollarsper cubic yard. This materialis" of very fine mesh of which only grab samples have so far been obtainable,

There are immense deposits of this material which is particularly amenable to flotation and amalgamation, and occurs at depths as great as 160 fathoms, and which is ready for milling operations directly in the form in which it is recovered.

The main object of this invention -is to provide a dredge which can be operated successfully at the maximum water depths of the aforementioned deposit, which in places approximated one thousand feet below the surface; to recover this material and subject it to flotation, amalgamation or other suitable recovery processes.

Another object of the invention is to providea dredge with necessary'driving motors enclosed in a housing which is effectively sealed against the high water pressures existing at such depths and all other depths, to insure the uninterrupted operation of the dredge.

A further object of the invention is to provide a dredge as an integral unit, surface controlled, self-operating, and which is raised and lowered by means of a flexible line through the medium of a winch or hoist, and which dredge will be selfanchoring against rotation on its own axis when the dredge is operated.

A still further object of the invention is to utilize the pressure of the water for effecting the sealing of all crevicesin the motor housing, to prevent leakage or ingress of water especially about protruding shafts, urged by the high water pressure existing about the housing, and to insure the uniform and uninterrupted lubrication of the shafts projecting through the housing walls.

Other objects and advantages of the invention will become apparent as the following description is read on the drawings forming a part of this v specification, and in which similar reference characters are used to indicate similar parts throughout the several views, of which;

Fig. 1 is a sectional elevation through the in- 40 vention with a portion of the receiver broken out.

Fig. 2 is a section taken on line 2--2 of Fig. 1.

Fig. 3 is a detail sectional view of the pressure equalized sealing means, shown on an enlarged scale.

Fig. 4 is an enlarged fragmentary sectional elevation showing the cutter head mounting means.

Fig. 5 is an enlarged fragmentary sectional elevation through the driving side of the cutter head.

Fig. 6 is a modification of the system of packv ing. a Fig. 7 is a modification of the system of packing shown in Fig. 3. V

Fig. 8 is a sectional elevation through the entrapment valve.

Fig. 9 is a modification of the sealing means.

The invention consists of a deep-sea dredge incorporating a sludge receiver, sludge admitting and retaining means, sludge dumping means, driving means for the sludge dumping means, a cutter head, driving means for the cutter head, a spud or anchor, driving means for the spud, a motor housing or enclosure for the driving motors, means for sealing crevices, or the shafts passing through the walls of the enclosure against ingress of water under varying pressures, valve means normally open, and closed by hydrodynamic pressure during raising of the dredge, and flexible means for raising and lowering the dredge to the bottom of the sea. I

The sludge receiver I0 is preferably made cylindrical in form and of any desired length dependent on the nature and depth of material being excavated, a length of ten feet being satisholes I2 provided to permit the escape of en trapped water from the receiver as the sludge is admitted at the lower end. A foot I3 is suitably fixed to the lower end of the tube and forms one cooperating face of the dump joint.

The sludge admitting and retaining means is diametrically coextensive with the receiver and is associated with the dumping means and consists of a valve system including bearing faces I4 on which the free edges of the flap valves I5 rest, one of which is shown raised away from the rest I4 for admitting sludge as the receiver settles into the body of sludge. These flap valves are closed by the weight of the sludge when the dredge is lifted, and form a perfect seal to retain the sludge within the receiver when the dredge is raised to the surface.

These flap valves are secured between the annular flange I6 and the ball bearing shroud H by means of the bolts I8, the flange I6 being formed integral with the dump body I9. With this valve system it will be noted that as the receiver settles into a bed of sludge, the sludge is admitted into the receiver, the superposed water escaping through the holes I2, or opening 92 controlled by valve 93.

The sludge dumping means consists of the dump body I9, which has an inside diameter equal to that of the tube I0, and has the inwardly projecting annular flange I6 integral therewith. An outwardly projecting annular flange 20 has its top face forming the cooperating face of the dump joint 2I. Another outwardly projecting annular flange 22 terminates in an upstanding flange 23 to which the gear shroud 24 is bolted or otherwise affixed, the flange 22 coincidently forming on its lower surface a shroud for the gear 25, which encompasses the dump body below the flanges 2223.

The hinge for the dumping means consists of a hinge eye 26 which is fixedly secured to the tube I0, and hinge straps 21 which are fixedly secured tothe shroud 24 or body I9, as may be found desirable, the pintle of the hinge being shown as a bolt 28. It is important that the pintle be located above the plane of the dump face 2| so as to cause recession of the gear from the pinion as the dump body is dropped, and to insure clearshrouds.

The cutter head has a sweep diametrically coextensive with the bottom of the receiver and consists of a cutter holder 29 to which the cutters 30 are secured by known means, this cutter holder being integral with the gear 25 and gear shroud 3|, whereby, when the gear is rotated, the cutters are operated, agitating and lifting the material, which is admitted through the valve system to the interior of the receiver.

The cutters are replaceable, and are formed to the shape most suitably applicable to the particular material to be excavated. V

The driving means for the cutter head consists of the gear 25, which is supported by the ball bearings 32, which cooperate between the substantially semi-circular raceways formed respectively in the outer face of the dump body below the flange 22, and the inner face of the gear rim, the balls being inserted through a suitable opening, which opening is afterward plugged with a grooved plug registering with the raceway as indicated at 33, the plug being in position when the raceway is machined. The balls obviously support the gear and cutter head on the dump body and coincidently form a substantially frictionless bearing for the gear.

The gear 25 meshes with a pinion 34 which is rotatable in the bearings 36 and 31 which are fixedly mounted on the tube I0, and the pinion is provided with suitable shrouds 38 and 39, which are in no way connected to the dump body or cutter head, but are supported by the bearing 36. However, these shrouds have edges formed complementary to the contour of member 3| and to a cut-out portion of the flange 22.

The shaft extends into the sealed motor enclosure 40 through a special pressure-equalizingpacked bearing 4I and'has a bevel gear 42 affixed at its upper end. This bevel gear meshes with a mating bevel pinion 43 which is fixed on the shaft of the motor 44. Thus, when the motor is operated, the shaft 35, through pinion 34 drives gear 25 and its integral blade holder 29 with its blades, cutting downwardly into the bed, the sludge being admitted by the valve system into the receiver.

As the boring process continues, the dredge settles down into the bore formed, since the material excavated will not support the dredge by the superficial surfaces exteriorly of the cutters, and where the sludge is sufliciently soft or miry, it is unnecessary to operate the cutter head, since the receiver will sink into the bed' while the sludge passes through the valve system into the receiver.

The spud consists of a bar or drill 45, eccentrieally located and which projects and operates in advance of the cutter head and is rotatably mounted in a bearing spaced from the bearing 36, and preferably formed in the same casting, and is thus mounted on the receiver proper, and due to its location and operation in advance of the cutter head, it maintains the dredge against rotation on its own axis when the cutter head is operated, and thereby forms an anchor against rotation of the receiver while permitting the receiver and cutter head to settle into the bore as the bore is formed.

The driving means for the spud consists of a pair of mating spur gears 46 and 41 respectively fixed on the spud shaft 43 and drive shaft 35,

fixed on the vertical shaft 35, which in turn is whereby the spud is driven in unison with, the

cutter head, although at a higher speed.

The driving means for the dumping means consists of an electric motor 49 having a shaft the outer end of the shaft having a rope sheave 55 secured thereon and a cable 56 windable thereon, and which cable passes through an opening I, the terminal end of the cable being secured .to the dumping means through a lug 58, which is fixed in the wall diametrically opposite the hinge 28.

The means for sealing crevices or shafts passing through the walls of the housing or motor containing enclosure is of especially vital importance, since the failure of all such projects, in

connection with deep-sea dredging is attributa-' ble to the failure of all methods of packing heretofore used. My method of packing has been under continuous test, submerged in water under eight hundred pounds pressure for many months with no evidence of seepage discernable. This pressure is equivalent to a depth of eighteen hundred and forty feet or three hundred and seven fathoms.

This system of sealing is equally applicable to diving suits, diving bells and other sub-sea devices, and its success is dependent upon the reactive pressure of the water of submergence against ingress of the same water throughalubrieating medium of higher viscosity than the water, the packing being increased in resistance and effectiveness as the degree of submergence and the viscosity of the lubricant is increased.

The simplest form of this system is clearly illustrated in Fig. 3, in which a bearing ll is submerged in the water 60, and is provided with the usual bushing 6|, and a special bushing 62, in which the shaft 63 is rotatablymounted. The bushing 62 is chamfered to cooperate with the chamfered collar 64, and the pressure of the water at the end of shaft 63 forces the collar 64 against the chamfered seat of the bushing 62, since no pressure exists at the other end of the shaft, which is within the enclosure 40. This feature is not in. itself a perfect seal, but merely an auxiliary expedient toward assuring the desired reactive pressure against the other associated elements and to form a seal for the grease, and to increase the pathway and its tortuosity for water of ingress.

An annular chamber 66 is formed in the bearing and encompasses the shaft 63 and is preferably located closer to the end 59 of the bearing than it is to the end 61, and a cylinder 68 filled with a lubricating medium communicates with this chamber, and thence with the bearings.

A piston 69 is urged by a spring 10 under normal lubricating pressure, and the hydrostatic pressure of the surrounding water is transmitted through suitable openings 1! to the top of the piston. A fluid passage 12 communicates between the chamber 68 and a groove 13 formed in the. joint for sealing the joint against ingress of water.

As will be noted, the pressure of the water is equal per unit of area at the points 1!, I5, and on the top of the piston 59. v

With a fluid ofthe same viscosity filling the cylinder, as that hr the water, there would be no sealing effect, except as to the chamfered-col- .lar and its seat. However, with a substantially heavy oil or grease in the cylinder, under normal atmospheric conditions, the spring urges the lubricating medium into the crevices and between the shaft and its bushings, this being the condition of non-submergence.

When the dredge is submerged, the pressure on the piston is increased just as the pressure at 14 and ii-is increased, and the excess pressure of the spring is still maintained, operating under the same conditions as previously, to lubricate the bearings. The pressure exerted on the grease through the piston by the water is .equal-' ized by'the pressure of the water, on the grease at the end of the bearing. The shaft is forced back by the pressure on the end of the shaft against either a straight or chamfered collar and forms a seal to back up the pressure of the grease.

The break-down pressure of a thin film of grease chamber to 59, thus the resistance of the grease a against urgence by the piston is less at 16 than it is at I1, so that with proper proportioning, the

seal will operate without the collar 64. Therefore the pressure is equalized between 18 and 14 in respect to the piston and increased at 18 in respect to the spring 10. v

The constant excess pressure of the spring overcomes any breaking down of the grease adjacent the outer end of! the bearing and constantly urges a slight amount of grease from the point 14, irrespective of the hydrostatic pressure.

Obviously, the cylinder may be inverted and carried to a greater depth to secure the added urgence for the grease, however, the matter is simplified by the use of the spring. A rubber washer or other packing means such as a gland may be used additionally as indicated at 79 if desired, and in some cases may be desirable, especially to prevent escape of grease into the enclosure.

The motor housing or enclosure 40 is made of suitable shape, material and strength to withstand the highest hydrostatic pressures to which, it is to be subjected. The sealing means is entirely automatic in its action, since any increase in hydrostatic pressure urging ingress of water through the crevices or about the shafts is immediatelycounteracted by the same increase in pressure on the lubricating medium. the spring providing the excess urgence of the grease necessary toinaintain a supply at the end of the bearing.

. Furthermore, any increase in hydrostatic pressure on the end of the shaft at 65 increases the thrust on the collar 64 while'the pressure on the grease in the cylinder provides the necessary lubrication to the collar.

' The flexible raising and lowering means forthe dredge consists of a chain or cable 80 which is suitably anchored at the transverse center of gravity of the unit, whereby, when the unit, or

dredge, is lowered, it will strike the bottom .of I

rotation by the spud 45, which may be made of any length necessary.

When a settlement of the dredge about equal to the length of the receiver is gauged, the dredge is raised to the surface'by means of suitable winches or hoists (not shown), the valve system retaining the sludge in the receiver.

When the dredge is ready to be dumped, the motor 49 is cut in circuit through a suitable reversing'switch (not shown), which through the cable 56 permits the dump body IS with all of its associated parts to swing about the pivot 28. The teeth on the pinion 34 and gear 25 are suitably end chamfered to cause unobstructed registration when the dump body is again closed by the motor 49.

Where a watery pulp is encountered, the holes l2 must be dispensed with, and a suitably valved opening used, such as that shown in Fig. 8, in which a flap valve 93 having a resilient facing 94 is retained partly open under atmospheric pressure by a spring 95, and fully open by the rush of water as the dredge is lowered, and retained tightly closed by the urgence of the water when the dredge is raised, sealing the receiver.

Three modifications of the system of packing are shown, all of which are effective.

In Fig, 6, the shaft 82 has an integral collar 83 and a slip collar 84 urged apart bya resilient washer 85 which tightly grips the shaft, and which may be circumferentially grooved as indicated at 86 and provided with an encompassing spring 81, the collars bearing in seats as shown.

By this means, the water of ingress is forced to follow a circuitous route about the collars and through the grease in the chamber. Felt washers are additionally provided.

Both of these collars may be mounted free on the shaft, if desired. The thrust of the shaft is taken up by the ball bearings 81', and the resilient washer tightly grips the shaft and urges the collars to their seats, forming a perfect seal in conjunction with the grease under pressure.

In Fig. '7, the bevel collar 64 on shaft 63 is re lieved of the thrust exerted by the water on the end of the shaft, this thrust being absorbed by a fixed thrust collar 89, the bushing 62 being adjusted to contact collar 64 to any desired degree of pressure by means of the gland 90 which is locked in adjusted position by the lock nut 9|. Thus the bearing of the bevel collar 64 may be adjusted to the most suitable contact pressure.

In Fig. 9, another modification is shown in which opposed bevel collars 96 and 91 are provided, the collar 96 absorbing the thrust, and collar 91 forming a seal in cooperation with the bearing 98, which is adjustable relative to the collar by means of the gland 99, the grease in the chamber and bearings under both spring and hydrostatic pressure effectively sealing the shaft against ingress of water.

Having described an operative device for,,and

method of deep-sea dredging, it will be understood that variations in construction-and arrangement of parts, or in the method, which are consistent with the appended claims may be re:

sorted to without detracting from the spirit or scope of the invention or sacrificing any of the advantages thereof.

I claim:

l. A submarine dredge, in combination, sludge receiving means and sealing means therefor including sludge retaining means and releasing means for the retaining means, boring means and driving means including an enclosure therefor, and means actuated by the external water pressure for maintaining said driving means against ingress of water thereto, anchoring means for maintaining said receiving means against axial rotation relative to a sub-surface, and flexible raising and lowering means for said dredge.

2. A submarine dredge, in combination, a cylindrical receiver, a motor housing mounted at the top of said receiver and a motor within the housing and having a drive shaft projecting through the wall of the housing and a bearing for the shaft, an annular chamber formed intermediate the length of the bearing about the shaft and a lubricating medium within the chamber, means for transmitting the pressure of the water to the lubricating medium to counteract the pressure of the water urging ingress between the bearing and the shaft to prevent ingress thereof to the motor and to lubricate the shaft, a valve system at the lower end of said receiver for-admitting sludge into the receiver and for retaining the admitted sludge, a rotary cutter below the valve system driven by said shaft, means for dumping the sludge from the receiver, a spud actuated in advance of the cutter for anchoring the receiver against rotation, and flexible raising and lowering means for said dredge.

3. A submarine dredge, in combination, a sludge receiver and anchoring means therefor, boring means rotatable independentlyof the receiver and following the anchoring means, driving means for the boring means and for the anchoring means, an enclosure for the driving means and a driving shaft projecting through the wall of the enclosure, means actuated by the external pressure of the water for lubricating the shaft against the external pressure of the water and preventing ingress thereof, means for admitting sludge to the receiver and for retaining the sludge therein, means for dumping the sludge at will, and means for raising and lowering the dredge.

4. In combination, a receiver and hydrodynamically actuated sealing means and gravity actuated entrapment means therefor, a housing, an electric motor in said housing and having a drive shaft projecting through the wall of the housing, means associated with the shaft and actuated by the external pressure of water for counteracting the pressure of the water against ingress about the shaft, a cutter head on said receiver for urging said receiver into the sludge, means for driving said cutter head by said shaft, and means associated with said receiver and cooperating with the sludge for maintaining said receiver against rotation as the cutter head is rotated.

5. In combination, a receiver including hydrodynamically actuated sealing means and resiliently actuated sludge entrapment means, a housing, an electric motor in said housing and having a drive shaft projecting through the wall of the housing, means associated with the shaft and the housing and actuated by the external pressure of the water for counteracting the pressure into the receiver and retaining the admitted sludge, and means for dumping the sludge at will.

6. A submarine dredge, in combination, a receiver including hydrodynamically actuated sealing means and resiliently actuated sludge entrapment means and a cutter'head for the receiver, a motor enclosure integral with the receiver and a motor within the enclosure, a drive shaft projecting through the wall of the enclosure for driving the cutter head, means actuated by the existent external pressure of the water for counteracting the pressure of the water about the shaft to prevent ingress thereof, said entrapment means retaining sludge in said receiver and means for dumping the sludge from the receiver at will, flexible raising and lowering means for said dredge, and anchoring means associated with said receiver and cooperating with sub-surface sludge for maintaining said receiver against axial rotation when the cutter head is driven.

'7. A submarine dredge comprising a cylindrical receiver, a cutter head rotatable independently of the receiver and mounted at the lower end thereof, a spud associated with said receiver and operating in advance of the cutter head for maintaining said receiver against axial rotation when the cutter head is operated, means for admitting sludge into the receiver as the receiver is advanced into a bed of sludge and for retaining said sludge means actuated by hydrodynamic pressure when the receiver is raised from the bed sealing the receiver against circulation or passage of bed, means for driving said cutter head and said spud, means for dumping said sludge, and flexible raising and lowering means for the dredge.

9. In combination with a gravity operated submarine dredge having a receiver provided with sludge admitting and retaining means and dumping means; a spud associated with the receiver and operated by said driving means in advance of the cutter head for maintaining the receiver against rotation on its own axis to permit driving of the cutter head independently of the receiver, and flexible raising and lowering means for the dredge.

10. A submarine dredge, in combination, sludge receiving means, sludge retaining means diametrically coextensive with the receiving means and releasing means therefor, boring means having a sweep coextensive with the receiving means and driving means therefor, and means actuated by the external water pressure intaining'said driving means against ingress of water thereto, power driven rotary, eccentrically located anchoring means maintaining said receiving means against rotation relative to a sub-surface, and flexible raising and loweringmeans for, said dredge.

11. A submarine dredge, in combination, sludge receiving means, sludge retaining means and releasing means therefor, boring means and driving means therefor, means actuated by the external water pressure maintaining said driving means against ingress of water thereto, anchoring means maintaining said receiving means against rotation relative to a sub-surface, flexible raising and lowering means for said dredge, and valve means for said receiver maintained in normally open position under static pressure and maintained in closed position under the influence of hydrodynamic pressure as the dredge is raised through the water to prevent escape of sludge fromthe receiver. a

12. A submarine dredge, in combination, sludge receiving means, sludge retaining means diametrically coextensive with the receiving means and releasing means therefor, boring means having a sweep coextensive with the receiving means and driving means therefor, means actuated by the external water pressure maintaining said driving means against ingress of water thereto, power driven rotary, eccentrically located anchoring means maintaining said receiving means against rotation relative to a sub-surface, flexible raising and lowering means for said dredge, and valve means for said receiver maintained in normally open position under static pressure to permit reception of sludge and escape of water from the receiver and maintained in closed position under the influence of hydrodynamic pressure as the dredge is raised through the water to prevent escape of sludge from the receiver.

13. A submarine dredge, in combination, a sludge receiver and anchoring means therefor,

boring means rotatable independently of the re-' ceiver and following the anchoring means, driving means for the boring means and for the anchoring means, an enclosure for thedriving means and a driving shaft projecting through the wall of the enclosure, means actuated by the external pressure of the water for lubricating the shaft against the external pressure of the water and preventing ingress thereof, means for admitting sludge to the receiver and for retaining the sludge therein, means for dumping the sludge at will, means for raising and lowering the dredge, and valve means for said receiver maintained in normalopen position except under the influence of hydrodynamic pressure created by raising of the dredge through the water and which closes and maintains the valve in closed position.

14. A submarine dredge, in combination, a cylindrical receiver, a motor housing mounted at the top of the receiver and a motor within the housing and having a drive shaft projecting through the wall of the housing, means utilizing the external water pressure for counteracting the pressure of the water urging ingress about the shaft to the housing, a valve system at the lower end of the receiver admitting sludge to the receiver and for retaining the admitted sludge, a

' pressure created by raising of the dredge through the water and which closes and maintains the valve in closed position to air-lock the receiver to prevent escape of sludge.

15. In combination, a receiver, a housing, an electric motor in said housing and having a drive shaft projecting through the wall of the housing,

means associated with the shaft and actuated by the external water pressure counteracting the pressure of the water urging ingress about the shaft, a cutter head at the bottom of said receiver for urging said receiver into the sludge, means for driving said cutter head by said shaft, rotatable means associated with the receiver and driven by said shaft and cooperating with the sludge for maintaining said receiver against rotation as the cutter head is rotated, and valve means for said receiver maintained in normal open position except under the influence of hydrodynamic pressure created by raising the dredge through the water and which closes and maintains the valve in closed position to prevent escape of sludge from the receiver.

16. In combination, a receiver, a housing, an electric motor in said housing and having a drive shaft projecting through the wall of the housing, means associated with the shaft and the housing and actuated by the external water pressure for counteracting the pressure of the water seeking ingress about the shaft, a cutter head at the lower end of said receiver urging said receiver into sludge, means for driving said cutter head by said shaft, boring means operating in advance of the cutter head into the sludge maintaining the receiver against rotation as the cutter head is rotated, means for admitting sludge into the receiver and for retaining the admitted sludge, means for dumping the sludge at will, and valve means on said receiver normally open to permit circulation through the receiver and closed and maintained closed through the influence of hydrodynamic pressure created by upward movement of the dredge through the water.

17. A submarine dredge, in combination, a receiver and a cutter head mounted for rotation at the bottom thereof, a motor enclosure integral with the receiver and a motor within the enclosure, a drive shaft projecting through the wall of the enclosure for driving the cutter head, means actuated by the external water pressure for counteracting the pressure of the water about the shaft to prevent ingress thereof, retaining means diametrically extensive with the interior of the receiver for retaining sludge in said receiver and means for dumping the sludge from thereceiver at will, flexible raising and lowering means for said dredge, and power driven rotary, eccentrically located anchoring means associated with said receiver and cooperating with sub-surface sludge for maintaining said receiver against rotation when the cutter head is driven, and valve means on said receiver normally retained in open position to permit circulation through the receiver and closed and maintained closed through the influence of hydrodynamic pressure.

18. A submarine dredge comprising a cylindrical receiver, a cutter head diametrically coextensive with and rotatable independently of the receiver and mounted at the lower end thereof, a rotatably driven spud associated with said receiver and operating in advance of the cutter head and eccentrically located for maintaining said receiver against axial rotation when the cutter head is operated, means admittingsludge into said receiver as the receiver is advanced into a bed of sludge and for retaining said sludge when the receiver is raised from the bed, means for driving said cutter head and said spud, and means actuated by the existent external water pressure for bucking water under existent pressure for driving.

19. A submarine dredge compriisng a cylindrical receiver, a prime mover and an enclosure therefor, and a shaft projecting through the wall of the enclosure, a cutter head diametrically coextensive with and rotatable independently of the receiver and mounted at the lower end thereof, a rotatably driven spud associated with said receiver and operating in advance of the cutter head and eccentrically located for maintaining said receiver against axial rotation when the cutter head is operated, means admitting sludge into said receiver as the receiver is advanced into a bed of sludge and for retaining said sludge when the receiver is raised from the bed, means for driving said cutter head and said spud, means actuated by the existent external pressure of the water for bucking water under the existent pressure seeking ingress to the prime mover aboutthe shaft, and valve means on said receiver normally retained in open position to permit cir 'culation through the receiver and closed and maintained closed through the influence of hydrodynamic pressure created in raising the dredge.

20. A submarine dredge comprising a cylindrical receiver, a prime mover and an enclosure therefor, and sealing means for the enclosure actuated by the existent external water pressure, a cutter head diametrically coextensive with and rotatable independently of the receiver and mounted at the bottom thereof, a rotatable spud eccentrically associated with said receiver and operating in advance of the cutter head maintaining said receiver against axial rotation when the cutter head is operated, means for admittin sludge into said receiver as the receiver is advanced into a bed of sludge and for retaining said sludge when the receiver is raised from the bed, means for driving said cutter head and said spud by said prime mover, means for dumping the sludge, and flexible raising and lowering means for the dredge.

21. A submarine dredge comprising a cylindrical receiver, an existent water pressure sealed enclosure and a prime mover therein, a cutter head diametrically coextensive with and rotatable independently of and mounted at the bottom of the receiver, a rotatable spud eccentrically associated with and operating in advance of the receiver for maintaining said receiver against axial rotation during operation of the cutter head,

means for admitting and retaining sludge in said.

receiver, means for dumping the sludge, means for driving said cutter head and said spud by said prime mover, flexible raising and lowering means for the dredge, and valve means normally retained in open position to permit circulation through the receiver, and closed and maintained closed under the influence of hydrodynamic pressure created by lifting movement of the dredge for preventing escape of sludge during raising of the dredge.

22. In combination with a gravity operated submarine dredge having a receiver provided with sludge admitting and retaining means and dumping means; a. rotatably driven spud eccentrically associated with the receiver operating in advance of the receiver for maintaining the receiver against rotation on i-ts'own axis.

a 23. In combination with a gravity operated submarine dredge having a receiver provided with sludge admitting and retaining means and dumping means; valve means associated with said receiver normally retained in open position to permit circulation through the receiver during operation of the dredge, and closed and maintained closed under the influence of hydrodynamic pressure when the dredge is raised through the water to prevent escape of sludge from the receiver.

24. In combination with a. deep-sea dredge having a receiver consisting of a container section and a dumping section hinged together; a rotatably driven cutter head mounted at the hot- 10 tom of the dumping section and having a sweep diametrically coextensive with the bottom of the dumping section, and a diametrically coextensive valve system within the dumping section above the cutter head permitting passage of material therethrough as the receiver settles into the bore' formed by the cutter head and entrapping the material and means actuated by hydrodynamic pressure sealing the receiver during raising of the dredge.

JOHN C. WILLIAMS.

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