US2207187A - Combined fluid and rotary driven drilling bit - Google Patents

Description

July 9', 1940.

J. A. ZUBLIN COMBINED FLUID AND ROTARY DRIVEN DRILLING BIT Filed July 15, 1938 2' Sheets-Sheet l Jomv A. ZUBL-IN,

y 9, 1940. J. A. ZUBLIN 2,207,187

COMBINED FLUID AND ROTARY DRIVEN DRILLING BI'I Filed July 15,1938 2 Sheets-Sheet 2 u'aH/v A. ZuaL/N,

Patented July 9, 1940 UNITED STATES PATENT OFFICE COMBINED FLUID AND ROTARY DRIVEN DRILLING BIT This invention relates drilling" tools, and more particularly to tools used in the rotary drilling of bore holes, such as oilwells. 1

It is an object of this invention to provide a drilling bit in which only a portion of the energy required to operate the bit is furnished through the customary rotation of the drill .pipe

Another object of this invention is to provide a drilling bit in which additional energy to ro tate the bit is furnished by fluid under pressure flowing through the drill pipe,

A further object of the invention lies in the provision of an improved drilling tooloperable by fluid pressure, the drilling .tool being in the nature of a water wheel or turbine.

Still another object of the'invention involves a drilling bit having its cutting elements rotatable by the-direct or indirect application of pressure, thereby increasing its efficiency of operation.

A further object of the invention involves a multiple jet turbine type of drilling bit in which the reactive force of the jets neutralize one another.

Yet another object of the invention lies in the provision of drilling toolsin which the cutters are rotated by means of fluid, the bearing loads imposed on the cutters by the formation being counteracted by the action of the fluid on the g cutters.

A further object of the invention'is to provide a drilling tool capable of producing a bore hole by the combined action of rotation of the drill pipe 7 and fluid under pressure causing roller cutters 45 to rotate This invention possesses many other advantages and has other objects that will become apparent from aconsideration of one or more embodiments cf the invention. For thispurpose, sev- 50 eral' forms are shown in the drawings accompanying and forming part of the present specification, which embodiments will now be described in detail, illustrating the general prin- ,ciples of the invention. However, it is to be un- 55 derstood that this detailed description is not to be taken in a limited sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure l is a partially longitudinal sectional view of one form of the invention. V

Figure 2 is a longitudinal section taken generally along the plane 22 in Figure 1.

Figure 3 is a fragmentary section showing the manner of assembling the .bearing balls in the 10 main bearing raceways.

Figure 4 is a partially longitudinal sectional view of another embodiment ofthe invention.

Figure 5 is a partially sectional view taken along the line 4-4 of Figure 3.

Figure 6 is an elevation of part of the turbine cutterassembly disclosed in Figures 4 and 5.

Figure 7 is a section taken along the line '|l ofFigure4; and v Figure 8,is a perspective view on an enlarged 20 scale of one of the buttons used in connection with the main bearing.

. In its generalv aspects, the present invention utilizes the energy in fluid under pressure forced through the drill pipe for rotating the rotary 25 cutting elements of a bit, relying upon the reaction of the cutters upon the formation to proter; or the fluid stream'can be caused to impinge directly upon the cutter teeth or elements themselves. By utilizing the energy in the circulating 'fluid, not only can the cutters be turned and 40 the proper bore hole size produced, but the same fluid exiting the cutters will keep the teeth clean and also the bottom of the hole. I

The contemplated drilling bits avoid the necessity fortransmitting the entire energy required for removing the formation through the drill pipe, inasmuch as utilization is made of the energy in the circulating fluid for turning the cutting elements, which is independentof rotation of the drill pipe. However, in the embodiments .ofn'iy invention disclosed in the drawings, it is preferable that the major cutting efl'ort be produced by utilizing the energy in the fluid under pressure, but the drill pipe still be rotated at a moderate speed to insure that all parts-0f the.

bore are covered to produce a round hole of the diameter desired,- such rotation also insuring that the drill pipe, which serves as a conduit for the fluid, will not become stuck in the bore.

In the form of invention illustrated in Figures 1 and 2, a shank 10 is provided having a tapered threaded pin II for attachment of the bit to the usual string of drill pipe (not shown). The shank possesses two depending leg I2, I3 between which arecarriedthe fluid rated water wheel or turbine cutting portions of the bit. Such cutting portions include a wheel or carrier I4 rotatably mounted upon a bearing support or sleeve I5, preferably through the agency of balls I6 rollable in the respective toric raceways II,

I8 provided on the exterior of the sleeve I and the interior of the wheel or carrier Id. The sleeve is carried by the legs by 'being received at one end in the bore I9 provided in one of the legs I2, with its other end being receivable in a bore or recess 20 provided in the other leg, I3. Rigid attachment of the sleeve to the legs is obtained by piloting the reduced extension I50. on the between the legs I2, I3 and the sleeve Ilplaced through the bore I9 in the leg I2, through the end of the sleeve in the recess 20 and by providing the taper or bevel 2I in the inner portion of the leg I3 for the reception of welding material 22 functionally integrating the sleeve to the leg. The other end of the sleeve is rigidly secured to the other leg I2 by means of thewelding material 23 fused to the sides of the leg bore I9,

the end of the sleeve I5 and the outer surface of a plug 24 threadedly received within the sleeve.

This plug is provided in. order to obtain a greater 'welded surface, and consequently a greater extent of attachment of the'sleeve to the leg and shank.

' A plurality of cutters 25 is rotatably mounted on the wheel or. carrier I4, being spaced circumferentially therearound, each cutter beingrotatable upon a bearing pin 26 receivable in aligned bores or holes 21 provided in the end walls .28, 29

01' the wheel. Each pin is rigidly affixed to the welds 30 can be provided. The wheel with the rollers assembled thereto can then be inserted inner raceway in the carrier, until the reduced end portion I511 of the sleeve is piloted in the bore 20 in the other leg I3. The sleeve can then be welded to the leg by welding in the tapered groove 2| provided between the leg and the raceway, the curvature being such as to provide sleeve. Thereafter, the balls It can be inserted into the respectiveraceways I I, I8 through the bores 33 extending inwardly through the endfaces of thecarrier. With the raceways fllled' with the required number of balls, a plug 34 can be inserted'into each of the bores and suitably attached thereto, as by welding. Eachplug 34 will have'preierably a curved surface for each continuity in the rolling of the bearing balls I6 on the inner portions of; the carrier. The end plug 24 can now be threaded intothe sleeve I5,

and the groove between the leg, sleeve and plug filled in with welding material 23, as aforementioned.

The general assembly described is similar in many respects to the types of drilling tools disclosed in the aforementioned patents. However, there are essential differences both in construction and mode of operation, which will now be indicated.

It is desired to rotate the cutters and their carriers by the action of fluid acting directly upon them. For this purpose, the sleeve I5 has extending at spaced intervals around its periphery a plurality of nozzles or orifices 35, 36. For the purpose of economy in manufacture, it is preferred to form the sleeve from several parts, in-

-cluding two annular end portions I5b, I5b, held together by the annular ring lie of welding material through which the nozzles 35, 36 extend and in which they are rigidly secured. One mode of assembling the nozzles includes placing them in proper angular and circumferential position on a suitable fixture, such as a copper plate, and

depositing welding material I5c therearound to form an annulus. This annulus of welding material carrying the nozzles is then welded to the end portions I5b, I5b, forming a functionally integral sleeve with the nozzles in proper assembled position.

The nozzles are positioned to direct jets of fluid, such as drilling fluid, on to both the carrier ll and teeth 25a of the cutters to produce their rotation. The carrier is provided-with spaced openings 31 defined bythe webs or ribs 32. The

leading side of the opening is shaped to simulate a turbine blade 38 so as to be capable of guiding and directing a fluid stream issuing from a nozzle on to the. cutter teeth 25aspaced around the periphery of each roller cutter 25.

'In order to convey the fluid to the sleeve I5, the shank is provided with a passageway 39 which will communicate with the string" of drill pipe and also with the sleeve. Fluid under pressure will enter the sleeve through the passageway and will have its pressure head changedto kinetic or velocity head as it passes through the discharge nozzles 35, 36. The fluid stream will strike against the wheel .blades 38, imparting some of its energy thereto to rotate the wheel on its ball bearings I6. However, only part of the energy will be consumed in such rotation, the fluid being guided by those blades, in a similar manner to stationary guide blades in a turbine, and will impinge upon the teeth 25a of each cutter to cause its rotation on its bearing pin 26.

It will be noted that about one-half of the cutters are in contact with the bottom of the hole. The turning effort imposed upon each .of these cutters under the impetus of the fluid stream issuing through the nozzles will force the carrier or wheel I4 to rotate, in view of the gearing effect of the teeth with the formation, causing the cutters to roll or walk alongthe formation and rotation of the carrier I4 ion the bearing sleeve I5 caused by the fluid engaging the cutter teeth 25ar and its direct action upon the carrier blades 38, the cutters will'be brought intermittently into and out of contact with the hemispherical hole bottom to achieve the function's mentioned in my aforementioned patents. Because of this mode ofoperation, only about one-half of the cutters will be in formation contact at any one time, the remaining cutters being "in reserved.

The cutters 25 will remove the formation by virtue of their contact with the bottom of the hole, tending to produce a bottom of semi-circular longitudinal section, equal in width to the length of the cutters. For the P p s of producing a hemispherical hole bottom, and consequently, a round bore of the required-diameter, the shank is also rotated by turning the drill pipe, which will cause the carrier or .wheel and the rollers to assume an infinite number of planes of rotation and produce a similar semi-circular sections, all of them combining to produce a hemisphere.

By the present invention, many disadvantages used consists of a rotary table and associated" associated with other methods of rotary drilling bore holes are overcome. The equipment now driving mechanism at the surface of the hole. and a bit at the bottom of the'hole, the motion of the table being conveyed tov the bit through a string of drill pipe serving as a power transmitter.

Because ofthis arrangement of parts, the entire torque necessary to turn the bit must -be-trans- .mitted through the drill pipe and its threaded joints, which must be of ample thickness and size to withstand the twisting stresses imposedupon.

them. This thickness in size must be, furtherv increased to enable the drill pipe to support its own weight in tension, due to the necessity. for the cable mechanism at thesurface or the hole to take weight off the bit and prevent buckling of the entire drilling string. Paradoxically,-this heavy drill pipe section increases the entire tension of the string, the pipe required for deep well drilling or the-nature of 9,000, 12,000 and 15,000

feet being of such heavy section that its maintenance in tension strains its Joints almost to the yield point. u

This invention overcomes the difiiculty' noted. The cutting action can take place at a more rapid rate than 'is obtainable through transmission of the entire energy through rotation of the drill pipe The twisting effort on the drill pipe willbe relatively small, since the main gutting effect occurs under the influence of the fluid streams issuing through the openings of the carrier, the

V rotation of the drill pipe only insuring that a proper holesize and shape will be produced. In .view of the lesser torque transmittable through the drilling string, each stand of pipe can be made much lighter. Furthermore, the morerapid rate at which the cutters are turned under the impetusof the fluid stream permits the use of lighter drilling weights, relieving the strain on the equipmentand also resulting in the production of a straight .hole. I-am aware that it has been proposed ten the energy in a stream of fluid for rotating a drilling bit by placing a long, multl-stage turbine near the lower end of a string of drill pipe,fthe driven end of the turbinebe coupled to the shankof the usual bit for rota g it at a rapid speed. Such arrangements possess the disadvantage that the turbines are susceptible to extreme w ear caused bythe heavy drilling fluid, nd they must also operate againstavery high'back pressure produced by the necessity for keeping the l bit and the hole clean through the fluid issuing through theusual nozzles presently "incorporated in rotary drilling bits. Manifestly, the use. of such high back pressures decreases the emciency of the turbine unit. Moreover, there is substantially no advantage in the use of such turbine combinations insofar as the drill pipe-and, joints aroma? uumber of i vdrilling string.

As distinguished from this latter combination of mechanisms, the present invention incorporates a turbine directly into the drilling bit, there being no need for operating against'high back pressures, .since the fluid exhausting from the a cutting teeth 25a into the hole has imparted its available energy towards rotating the carrier and cutters. .Nor is there any reactive torque imposed upon the string of drillpipe. It will be noted that the nozzle holes are positioned to rotate the cutters and wheels about axes substantially at right angles to the axis of the drilling string.

Consequently, there is practically no reactive torque onv the drill pipe. What reaction is present is practically neutralized in the drill bit itself because of the disposition oi the nozzle holes around the axis A--A of the carrier, the reactive forces of the streams issuing from the nozzle holes one half of the sleeve being substantially counterbalanced by the reactive force of the opposite grouping of nozzles. This nontransmittal of torque permits the use of lighter drill pipe, which decreases the tension in the 11-. will be noted that the fluid acting upon the cutter teeth not only urges their rotation together 'with thewheel or carrier, but also thoroughly.

effects their. cleaning. The fluid leaving the formation' contacting cutters will pass to the bottom of the hole, removing the cuttingstherefrom and carrying. them upwardly around the drill bit. Thus, separate cleaning nozzles are not necessary in this form of bit, eliminating the need for operation against higher .back pressures than. are Present in the bottom of the hole.

In the type of bit just described, only the lower half of the cutters in contact with the formation have loads .imposed upon them. Those in the upper half are out of contact and are therefore free to turn without restraint. If the same ex tent of fluid stream-were permitted to issue through the nozzles and strike the cutter teeth.

when the rollers were in their .upper position, they would be rotated atextre'mely rapid speeds, which motion would produce no useful function. Accordingly, although not essential, the nozzles 36 in the upper portion of the sleeve havea much smaller cross-sectional area than the nozzles 35 acting against the carrier and rollers that are in the lowergpositiori. These uppernozzles 38 will also strike against the side blades 38. of the wheel to assist in its rotation,. the fluid leaving these blades and acting upon the cutter teeth 25;; to

- rotate the cutters and insure their thorough cleansing by removing whatever matter has riot beendisplaced while they were in formation cont'act.- By decreasing the upper nozzle area the cutters out 'formation contact will not be rotated too rapi y, and will therefore -bepossessed of a longer effective life. I

If deemed essential, the uppernozzles 36 can be eliminated and the fluid stream be prevented from acting upon the cutters that are out of' formation contact, the rotation of the carrier successively moving the cutters'back into formation contact where they will again be acted upon by the fluid jet issuing from the lower nozzles of larger cross-sectional area.

As stated. above, the wheel blades 38 are so designed that the stream issuing from each nozzle will engage against them to impart only part of their energy thereto in causing carrier rotation. The fluid leaving the wheel blades will still have a high percentage of its kinetic energy remaining, the exiting portions of each wheel blade being so designed as to direct the jet materially inwardly of the outer .end of each tooth a. This design is preferred since wearing down or blunting of the cutter teeth incident to their digging into the formation will not permit the fluid to pass them by, the fluid stream being effective during the entire life of the drilling tool.

It will be noted that each cutter has a close fit with the curved portion 3Ia. of its confining recess to keepwindage losses and eddying to a minimum. It will be noted further that the fluid acting somewhat inwardly on the cutting teeth tends to resist centrifugal action trying to throw it outwardly. The inward thrust of the fluid also counterbalances the reactive force of the formation upon the cutter'teeth, thereby decreasing the bearing loads imposed by each cutter upon its bearing pin 26 and adding tothe effective life of x the drilling bit as a whole.

Tracing through a cycle of operation of a cutter beginning with its position as it moves into formation contact, the fluid will issue from one of the nozzles 35, striking against the bucket or blade 38 on the wheel or carrier, which will guide it on to the cutting teeth 25a, causing the rolling of the cutter on the formation in the manner aforementioned to carry the wheel along with it and produce its rotation on its main bearing l5. As the wheel rotates in a clockwise direction, as seen in Figure 2, the: stream issuing from the jet will pass directly through the wheel opening 31 without engaging the carrier blade 38,

its full force being expended against the teeth of the cutters, which .will function as water wheel buckets or turbine blades, the cutter being further rotated and carrying the carrier with it. As the carrier continues to rotate, the fluid stream will engage against the back portion 38a of the wheel opening, from where it. will be deflected against the cutter teeth in the proper direction for continuing rotation of the cutter 25. From this position, the cutter will passsuccessively under the influence of the other nozzles 35, where the operation just described will be' repeated, until the cutter comes out oi formation contact, after which it will be cleansed by the smaller Jets issuing from the upper nozzles is inclined to the horizontal. S uch inclination permits theincorporation of a properly designed flow channel 39 in the shank leg IS in view of the greater'amount of shanktmaterial that.

can be placed on that portion of the shank.

With this inclination, the cutters engage the bottommost portion of the hole almost entirely to one side of the hole axi's B--B to avoid dead centers, b'ut neverthless overlap the hole axis to a slight extent to insure that all parts of the formation will-be covered by the cutting teeth in cooperation with the rotation of the tool through the agency of the string of drill pipe.

In the forms of invention illustrated, the drill pipe is rotated at a moderate speedso that the cutters cover all parts of the hole bottom. Such rotation is taken advantage of by offsetting the tapered pin II on the upper end of the shank with respect to the hole axis 3-3 to make available the eflects of centrifugal force incident to eccentric rotation of a drill collar, as explained in my Patent No. 2,119,619, by virtue of which an undersized bore is prevented as wear occurs on the cutter teeth and other parts.

The number of rollers 25 spaced around the carrier is preferably an odd number, to avoid flat spots. While seven rollers are shown in the figures, it is to be understood that the invention is not limited to that number, those used being dependent upon the design of the cutters and the size of the tool. It will be further appreciated that the cutter teeth can assume various other shapes than that disclosed and have various inclinations.

The form of invention shown in Figures 4 to 8, inclusive, operates in a manner similar to the first described embodimentr That is, the major cutting and turning effort on a cutter mechanism is exerted by a fluid stream, assurance being had that all parts of the hole are covered by supplementing this effort through rotation of a' string of drill pipe and shank of the tool connected thereto. f

The drill bit includes a plurality of depending legs 40, 4| extending from the shank body 42, the upper end of which carries the usual threaded pin 43 for connecting the bit with the string of drill pipe (not shown).' One of the legs 40 has formed integrally therewith a bearing supporting member 44' adapted to carry a cutter assembly 45, to be described hereinafter. The end of the bearing supporting member is provided with a reduced extension 44a fitting into a bore 46 formed in=the leg 4| of the shank 42, which leg, after the cutter assembly has been placed onthe bearing supporting member, can

/ adapted to cooperate with an inner bearing race 49 containing complementary toric raceways '50.

Between the raceways are placed balls 5| which will serve-to transmit bearing loads between the carrier and inner race.

Prior to the placing of the separate long leg be.weldefgl ,at its upper end a to the shank body 4| on the reduced bearing extension 44a and its welding thereto and to the shank body, the carrier 46 is .placed over the inner-race 49 and the bearing balls 5| introduced into the raceways 48, 50 through the holes'liformed within the inner race and communicating with respective race=- ways. Thereafter, buttons 53 havinganupper cylindrical portion Ila and a lower rectangular portion 53b are inserteddnto the bores, serving to prevent the balls from falling from the raceway while at the sometime providing a substantially continuous raceway on which the balls can roll as the carrier rotates. The lowermost-por tlon ofthe butto is made. rectangular in shape so as to be cap ble of riding in the keyway I4 1 formed in the bearing supporting member '44,

rotation with respect to the bearing supporting member. As'explained in my application enand thus serving to lock the inner race 48' from tiled Compact bits, flied February 21, 1938, Secave face to the action of the fluid stream leavrial No;- 191,622, in which the bearing and shank ing the nozzle, with the back faces of the buckets construction is being claimed, the buttons 53 being preferably convex. The center hne of the serve the three-fold function of providing ,a nozzle is so placed as to' intersect the central substantially continuous raceway, preventing the plane of the carirer, in order that the fluid stream balls fromfalling from the raceway, and keying issuing therefrom will be directed against the the inner raceway to the bearing supporting member.

Upon assembly of the carrier 46 on the main bearing 49 and the insertion of the balls 5| in the manner aforementioned, this entire assembly is slid over the bearing-supporting member 44 with the rectangularbutton heads 53b riding in the keyway 54. Thereafter, the long leg 4| is placed over the reduced extension, 44a with' the boss 55 on the leg abutting the end 56 of the inner race 49, and causing the opposite end- 51 of the race to abut the boss 58 formed on the other shank leg 40. Upon welding the upper part 4| a of the leg to the shankand the lower part 4| b to the reduced extension, a rigid shank assembly results for carrying the cutter assembly for rotation with respect to the shank about a preferably inclined axis 0-0 with the bottommost cutter teeth 41 positioned mainly to one side of the axis 13-1). of the hole, in a similar manner to the inclined positioning of the carrier i4 described in connection with the Figure land 2 embodiment. J

As described in my copending application, the cuttings are removed from the bottom of the hole by discharge of fluid from a nomle 59 threadedly held in the lower portion of the short leg 40, which. has a conduit 60 therein for establishing communication between the shank passageway 8i and the nozzle. The fluid will issue from this lower nozzle and sweep transv'ersely across the hole bottom for effectively removing the detritus.

The upper portion 42w of the shank adjacent the periphery of the cutter teeth 41 is positioned closely adjacent the ends of the teeth, embracing a material angular distance of the carrier circumference. A fluid channel 62 is provided in the upper shank portion,'communicating with the fluid passageway 6| and terminating at the embracing shank portion 42a adjacent the periphcry of the cutting teeth. A separate or integral .The wheel 46 will be rotated through the action of the fluid stream issuing from the nozzle to remove the formation, producing a substantially semicircular hole bottom in longitudinal section equal in width to the distance across the cutter teeth 41. as described in connection with the Figure 1 and 2 specie, the shank will be rotated through the usual string of drill pipeto cause the carrier 46 and its cutting teeth 41 to assume;

an infinite number of rotational positions and thereby produce ahemispherical hole bottom with a bore of the required "diameter.

Although the cutter teeth 41 can assume various shapes, it is preferred to form them in a manner similar to the buckets on-a water wheel.

. For this purpose, each tooth or blade 41 is formed with two bucket sections 41a, 41b symmetrically disposed about the central rotational plane of the buckets, striking them at'the central plane where it will be divided and deflected therealong to-- wards thesides of the blades or wheel. The nozzle is inclined at a proper angle so that the fluid issuing therefrom can strike successive blades and impart its kinetic energy thereto to cause rotation of the wheel and the dig in of the hole. as described above. Suflicient clearance is allowed between the ends of the blades or teeth and the legs 40, 4| of the shank to preventany obstructions to the' flow of fluid from the teeth and decreasethe back pressure to that present at the bottom of the hole.

The arrangement described will resistthe centrifugal action tending to throw the fluid outwardly since the direction of the stream is partially downwardlyinto the wheel or carrier. This will eliminate interference between entering and exiting fluids. The downwarddirection of the fluid stream will also relieve the formation thrust on the cutters from being communicated to the bearings by virtue of its partial counteracting effect on such reactive forces. 4

I claim:

1. In an earth boring apparatus, a shank, a carrier, means rotatably mounting said carrier on the shank, and a pluralityof cutters rotatably mounted on said carrier, and fluid discharge means supported by said shank, said means being within said carrier and adapted to direct its disi ;:iharge against the cutters and cause their rota- 2. In an earth boring apparatus, a shank, a carrier, means rotatably mountingsaid carrier on the shank, a plurality of cutters rotatably mounted on carrier, and fluid discharge means cooperable'with said, shank and arranged to direct its discharge against those cutters in formation contact in a direction to induce rotation with respect to the carrier, and by their reaction on the formation produce rotation of the carriehon' the shank.

3. In an earth boring apparatus, a shank, a ,carrier, means rotatably mounting said carrier on' the shank, a plurality of cutters 'r'otatably,

mounted on said carrier, and fluid discharge means supported by said shank, said means being within said carrier and adapted to direct its 1discharge against the carrier and cause'its rota- 4. In an earth boring apparatus, a shank, a carrier, 'means rotatably mounting said carrier on the shank, a plurality of cutters rotatably mounted on said carrier, and fluid discharge means supported by said shank, said means being within said ,carrier and adapted to direct'its dis charge against the. carrier and cutters to cause their rotation.

5. In an earth boring apparatus, a shank, a

carrier, means rotatabty mounting said carrier 4 produce their rotation with respect tothe carrier.

6. In an earth boring apparatus, a shank, a"

carrier rotatably mounted on the shank, cutter -swheel or carrier, each bucket presenting a'conmeans rotatably mountedon said carrier, and 1s said transverse axis.

8. An earth boring tool comprising a shank fluid discharge means cooperable with said shank and positioned closely adjacent one or more of said cutters in formation contact, whereby to direct its discharge against said cutter means and produce rotation of said cutter means with respect to said carrier, and of said carrier with respect to the shank.

'7. In an earth boring apparatus. a shank adapted to rotate about the axis of the bore being produced,'a carrier rotatably mounted on the shank about an axis transversely of the bore,-

cutter means rotatably mounted on said carrier; and fluid discharge means cooperable with said shank and positioned closely adjacent one or more of said cutters in formation contact, whereby todirect its discharge against said cutter means and produce rotation of said cutter means with respect to said carrier, and of I mounted on said bearing support, a plurality of cutters rotatably, mounted on said carrier, 2. fluid passageway in said shank, -a fluid passagewa in said bearing support communicating with said shank passageway, and one or more fluid discharge means'extending through said bearing support to its passageway-and arranged therein to direct its discharge against said carrier..

10. An earth boring tool comprising a shank carrying a bearing support, a carrier rotatably mounted on said bearing support, a plurality of cutters rotatably mounted on said carrier, a fluid passageway in said shank, a fluid passageway in saidbearing support communicating with said shank passageway, and a plurality of nozzles I spaced around said bearing support and extendcarrying a bearing support, a carrier rotatably ing therethrough to its pwsageway, said nozzles being arranged to direct their discharge against said cutters tocause their rotation.

- 11. An earth 'borlng tool comprising a shank mounted. on-said bearingsupport, a plurality of I cutters rotatably mounted on said, carrier, a fluid said carrier about,

passageway in said shank, a fluid passageway in said bearing support communicating with said shank passageway, and. a plurality of nozzles spaced around said bearing support and extending therethrough to its passageway, said nozzles being arranged todirect their discharges against said carrier to cause its *rotation.

12. An earth boring tool comprising a shank carrying-a bearing support, a carrier rotatably mounted on said bearing support, a plurality of cutters rotatably mounted on said carrier, a fluid passageway in said shank, a fluid passageway in saidbearing support: communicating with said shank passageway, fluid discharge means extending through said hearing support to its passageway, and blades on said carrier, saiddischarge means being arranged to direct its discharge against said carrier blades to produce rotation of the carrier;

13. An earth boring tool comprising a shank carrying a bearing support, a carrier rotatably mountedon said bearing support, a plurality of cutters rotatably mounted on said carrier, a fluid passageway in said shank,a fluid passageway in.

said bearing support communicating with said shank passageway, fluid discharge means extending through said bearing support to its passageway, and blades on said carrier, said discharge means being arranged to direct its discharge aga st said carrier blades, and said blades being so shaped as to guide and deflect said discharge against said cutters, whereby to produce rotation of said carrier and cutters.

14. Awearth boring tool comprising a shank carrying a bearing support, a carrier rotatably mounted on said bearing support about an axis, a plurality of cutters'mounted in recessesspaced around said carrier, a fluid passageway in said shank, a fluid passageway in said bearing support communicating with said shank passageway, fluid discharge means extending through said bearing support to its passageway, means including blades defining openings in said carrier communicating with said recesses, fluid discharge means extending through said bearing support to its passageway, said discharge means being arranged to direct its discharge through said opening for direct action upon said cutters and also against said blades.

15. An earth boring tool as defined in claim 14, the rotational axes of said cutters being lengthwise of said carrier axis. l

JOHN A. ZUBLIN.

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