US2950901A - Earth boring drill - Google Patents

Description

Aug' 30, 1960 A. A. MATHEwsoN, .1R 2,950,901

EARTH BORING DRILL Filed Dec. 25, 195'? 3r Sheets-Sheet 1 ///////-/7/f Y M 9 ILV Z M j .Q j E 1 EE: w f j c l Av/,f E911-lill! Aug. 30, 1960 Filed Dec. 23. 195'? A. A. MATHEwsoN, JR

EARTH BORING DRILL 3 Shets-Sheetl 2 LOAD All@ 30, 1960 'A. A. MATHEwsoN, JR 2,950,901

EARTH BORING DRILL United States EARTH BORINGl DRILL Arthur A. Mathewson, Jr., La Canada, Calif., assignor, by mesne assignments, to A. G. Bodine, doing business as Bodine Soundrive Company, Los Angeles, Calif.

Filed Dec. 23, 1957, Ser. No. 704,660 Claims. (Cl. Z55-4.4)

drill rod at a resonant frequency thereof. Such varia.

tions cause the drill rod to vibrate in a standing Wave mode either as a half wave, full wave, wave and one half, etc.

In the sonically vibratory drill disclosed in said Bodine patent, the drilling mud uid is pumped through the supporting drill string and the drill rod suspended at the end of the drill string and actuates a turbine which is disposed above an oscillator device comprising a plurality of rotatable weights cooperable to impart the longitudinal vibrations to the massive drill rod at substantially a resonant vibration frequency of the rod. One problem encountered in the construction disclosed in said Bodine patent wherein the turbine is disposed above the oscillator arises by reason of the tremendous axial loads which are impressed upon the turbine mounting shaft support bearings or thrust bearings, particularly when the drill reaches a substantial depth so that the hydrostatic load due to the height of the column of drilling uid above the turbine is substantial.

With said conventional construction, the oscillator is disposed within a cavity formed as an integral part of the massive vibratory drill rod or bar and the pressure within `said cavity is of the order of atmospheric pressure or slightly greater. Obviously, the pressure within the oscillator cavity is substantially less than the pressure of the drilling uid in the vicinity of the driving turbine, particularly when the turbine and oscillator have penetratedpto a substantial -depth in the earth. Consequently, the `load impressed upon the turbine mounting shaft bearings and arising from the height of the column of drilling fluid (the hydrostatic load on the turbine bearings) acts in a downward direction. The hydrodynamic load on said turbine bearings due in the pressure in the drilling fluid as it passes through the turbine, is likewise in a downward direction. Accordingly, said hydrostatic and hydrodynamic loads may both be considered as positive loads which are additive in their result on the turbine bearings so that the resultant load on the turbine bearings constantly increases to a point where at a certain depth the capacity of the bearings to absorb the turbine load thereon in a downward direction is exceeded.

The principal object of the present invention is to provide a driving device for a sonic earth boring drillv including a drilling fluid actuated lturbine and an oscilto the drop aent lator means wherein substantially greater drilling depths are attainable by reason of the fact that the limitation in drilling depths due to the fact that the turbine thrust bearings reach their capacity is avoided.

More particularly, it is an object of the present invention to provide a combined turbine assembly and oscillator device for a sonically vibratory drill wherein the turbine is physically disposed below the oscillator device so that the hydrostatic and hydrodynamic loads acting in axial `directions on -the turbine support bearings compensate for each other.

Even more particularly, it is an object of the present invention to provide such a combined turbine and oscillator device for a sonically vibratory drill wherein the hydrodynamic load on the turbine support bearings acts in a downward direction and the hydrostatic load on the turbine support bearings acts in an upward direction, thereby tending to cancel each other.

As a result of the construction of the combined turbine assembly and oscillator device as disclosed herein, it is obvious that it is theoretically possible to drill at depths substantially greater than would be possible With bearings of the same capacity but with the turbine assembly and oscillator devices reversed in their disposition in the drill rod.

A further and more limited object of the present invention is to provide a turbine and oscillator assembly for a sonically vibratory drill and including centrifugal pump means disposed immediately beneath the turbine support means for pumping fluid lubricant as itleaves the bearings through gearing mechanism disposed between the oscillator and turbine assembly and thence through the bearing assembly.

Another object of the present invention is to provide such a turbine and oscillator assembly and including a planetary gear set operatively interposed between the turbinel and the oscillator in such a manner as to provide an overdrive from the turbine to the oscillator drive shaft.

The foregoing objects and others, as well as numerous advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings, wherein:

Fig. l is a schematic illustration of a sonically vibratory drill rod suspended from a conventional earth bore drilling derrick;

Figs. 2A, 2B and 2C comprise detail sectional views of the turbine assembly and oscillator means comprising the subject matter of the present invention;

Fig. 3 is a graph disclosing the relative values of the hydrostatic and hydrodynamic loads and the resultant load impressed upon the turbine support bearings; and

Fig. 4 is an enlarged View illustrating certain features of the invention.

With reference now -to the drawings, wherein like reference numerals have been used in the diiferen-t views to identify identical parts, the combined turbine assembly and oscillator device comprising the subject matter of the present invention is represented generally by reference numeral 10, this device 10 being disposed at the upper end of a sonically vibratory earth boring drill rod, represented generally by r'eference numeral 11, which has an earth boring or penetrating bit 12 disposed at the lower end thereof. The longitudinally vibratory drill rod l0 is adap-ted to be suspended within an earth bore (not represented in the drawings) by means of a suspending drill string 13 which is held in place by means of a derrick 14 located at the earths surface above the bore being drilled.

It will suflice at this point to state that the combined turbine assembly and oscillator means 10 is disposed at the substantial upper end of the drill rod 11 at a velocity antifnode and that the turbine assembly and oscillator device 10 is adapted to impress longitudinal vibrations to Y mounted Within an outer drill pipe section 17 and the oscillator device or assembly 16 is xedly mounted within ya drill collar section 18. The drill collar sections 17 and 18 are complementarily threaded, as at 19 and are thereby adapted to be interconnected with each other.

The drill collar section 17 axially telescopes within the drill collar section 18 and is provided with an annular upwardly facing shoulder 20 within and against which the lower end of oscillator housing 21 is seated. The oscillator housing 21 is suitably fixed to said shoulder 2) by means of a plurality of bolts (not shown) which extend axially through suitable -apertures formed in shoulder 20 and in portion 22 of the oscillator casing 21.

The oscillator casing 21 is rather snugly received within 'the drill collar section 18 but is formed with two flat sides 18a and 18h which, together with the inner periphery of the drill collar 18 form drilling mud fluid passages for conveying mud fluid which passes down through an axial aperture through drill string 13 into the drill coll-ar section 18. The drill collar section 18 is internally threaded, as at 23 for the purpose of receiving external threads on the lowermost end of drill string 13. The section of drill pipe 17 is formed with suitable drill tiuid conveying passages 24 which mate with the passages between the oscillator casing 21 and drill pipe section 18 and the drilling mud fluid is thereby conveyed to a plurality of downwardly and inwardly directed openings 25 which lead to the turbine assembly 15. The turbine assembly is rotatably mounted and'held against axial thrust loads by means of a turbine mounting shaft bearing assembly 26. The bearing assembly 26 comprises a plurality of sets of ball thrust bearings 27 which have relatively rotatable elements respectively seated within a peripheral or annular raceway 28 formed within annular member 29 and around a turbine mounting shaft 30. The turbine mounting shaft 30 is formed with a collar 31 against which an abutment ring 32 is disposed, the ball bearing members 27 being disposed in abutment with ring 32 and held in place axially with respect to turbine mounting shaft 30 by means of a lock nut 33 threaded onto a threaded region 34 on turbine mounting shaft 30. The lock nut 33 is formed with a suitable groove for receiving a sealing and locking ring 35. `The ball bearing assembly is held in iixed relation with respect to the annular member v29 by means of a lock nut assembly 36 threaded into a suitable threaded region 37 formed on the inner periphery ofv member 29.

At the lower end of the turbine mounting shaft 30, it is reduced in diameter and splined, as indicated Iat 38, to form a turbine mounting hub 39 being similarly complementarily splined and thus received on the spline portion 38. The turbine mounting hub 39 is internally chamfered at 40 and 41 and is adapted to wedge against an annular wedge member 42 which -abuts a shoulder 43 formed by the enlarged portion 44 of the turbine mounting shaft 30. An annular washer-like member 45 is received around the turbine mounting shaft 44 and is formed with a complementary chamfered portion 46 adapted to abut against charnfered portion 41 of turbine mounting hub 39 in order to hold the hub in fixed relation on turbine mounting shaft 30. A suitable lock nut 47 is threadably disposed on a threaded region 48 of turbine mounting shaft 30 to hold the turbine mounting hub assembly in fixed axial position on the turbine mounting shaft 30.

Disposed coaxially and concentrically around portion 44 of turbine mounting shaft'30 is a sealing device, indicated generally by reference numeral 49.- Tlle seal l assembly 49 will not be described in detail as it does not form any specic part of the present invention. It will suice to state at this point that the seal assembly 49 comprises two pairs of cooperable substantially optically flat surfaces 51 and 52, respectively effective to isolate drilling mud fluid from a sealing fluid lubricant to be supplied by means hereinafter described, and to isolate said sealing mud fluid lubricant from the oscillator cavity within casing 21. A sealing means of a type suitable for use as the seal assembly 49 is shown in Hatch et al. Pat. No. 2,800,296, and further description thereof is not deemed necessary.

The turbine assembly 15 will now be described. The

vturbine mounting hub 39 is formed with a plurality of axially extending radially spaced apertures 53 adapted to be aligned with corresponding axially extending radially spaced apertures 54 formed on an inwardly directed flange 55 on Van inner shell ring 56of turbine assembly 15. A plurality of fastening bolts 57 respectively extend through aperturesV 53 and 54 in order to rigidly interconnect the inner turbine shell ring 56 with the mounting hub or web 39. The shell ring 56 is disposed coaxially and concentrically with respect to the -turbine mounting shaft 30 and surrounds a turned-down portion 58 on member 29, there bein-g some slight space between the shell ring 56 and the tumeddown portion 58. The lower end of turbine shell ring 56 similarly is disposed coaxially with respect to the turbine mounting shaft 30 and is disposed around and in spaced relation from a thin shell portion 59 of an annular member 60 which is keyed to a relatively short annular member 61 threaded into drilling collar 15, as at 62. Said annular members 60 and 61 Vare interconnected by keys 63. At its lower end, the drill collar 17 is internally threaded, as at 64 for receiving 'complementary external threads on -the next lower section of drill collar (not shown).

The inner turbine shell ring`56 is formed with a plurality of stages of turbine vanes 65 which are formed as an integral part of the shell ring 56 and formed of abrasion resistant metal. Alternately disposed between the stages of turbine vanes 65 arev a plurality of stages of stator vanes 66. The stator vanes 66 are respectively carried by individual outer annular shell rings 67, v

each of which is formed with outer peripheral splines 68 which cooperate with complementary splines 69 at spaced intervals on a stator mounting key 70 adapted to be received within a bore 72 formed within anelongated sleeve member 73. Said sleeve member 73 is held in fixed axial position against an annular ring 74 which' abuts-an inwardly directed shoulder 75 on member 17 by means of the annular member 61 which is threaded tightly against the other end of ring or sleeve 73 by means of threads 62. In order to retain the stator vanes 66 in axially lixed relation, a plurality of spacer rings 77 are spaced between adjacentY turbine vanel stages. A suitable sealing member 78 isv disposed between an inwardlyl directed shoulder 79 and the lower end of the lowermostV spacer ring 77 in order to hold the spacer ring 77 and the stator shell rings 67 in fixed axial relation.

In order to facilitate cooling of the inner shell ring 56 and the rotor vanes 65 drilling mud fluid is directed inside of the turbine shell 56 and outside of annular members 58 and 59. In order to accomplish this cooling it is not necessary that any large quantity of drilling mud iiuid be vby-passecl around the turbine assembly 15 as there would otherwise be too great a loss in eiciency of the turbine assembly. It is only necessary that a relatively` small portion of the drilling fluid be by-passed around thevanes 65 and 66 and for controlling this amount ofby-pass, a short pipe member S0 is disposed v within one of the apertures 54 andV is formed with a V'small-central' orifice 81. This Small orifice 81 willpermit a relatively small portion of the'drilling mud .uid'

to' pass between theturbine shell ting 56 and members of to by-pass the turbine vanes and stator vanes as to substantially decrease the etiiciency of the turbine assembly 15.

As will be readily understood, the mud uid passing from passageways 25 and into the space within the turbine shell ring 56, will have a tendency to exert considerable wear at the entrance to the annular passage between members 56 and 58 and, in orderto minimize this Wear, a suitable annular ring 82 of wear resistant material is shrink fitted around a cut away portion 83 formed on member 58.

The oscillator assembly comprises a plurality ofk rotatable Weights 85 and 86, each o f which is respectively carried by a collarsection 87 within which a pair of external roller bearing raceways 88 are mounted. Cooperable internal raceways 89 respectively correspond to each of the raceways 88 and a pair of sets of roller bearings 90 provide for free rotation of each of the WeightsSS and 86 around a sleeve member 91 which is supported by a coaxial support shaft 92 extending into opposed sides of oscillator casing member 21. Each of the weights 85 and 86 is fixed to rotate with a respective associated pinion gear 93 and 94, successive ones of said pinion gears 93 meshing with each other. The mounting shafts 92 are adapted'to be non-rotatable within casing member 21 and are held in substantially axially iixed position within said casing member by means of retainer members 95 respectively disposed `within openings 96 in each of the shafts 92 and threaded therein at threaded regions 97.

The oscillator mechanism \16 further comprises a pair of driving pinion gears 98 and 99 which mesh respectively with the iirst pair of weight driving pinion gears 93 and 94. The oscillator driving gears 98 and 99 are respectively splined onto hub portions 100 formedY on bevel gears 101 and 102 respectively. The bevel gears 101 and 102 are each rotatably mounted upon a sleeve 103 by means of ball bearing assemblies 104 and 105 and are held in spaced relation to each other by means of a pair of Belleville washers 106.- The sleeve 103 is concentiically mounted on a pin 107 which extends into apertures in opposite sides of casing 21 and which is held in a fixed axial position Within said apertures by n means of a retainer 108 threaded into the pin .107, as at 109.

A driving shaft -1'10 having a bevel gear 11-1 at one end thereof drives the entire oscillator assembly 16, the bevel gear i111 meshing respectively with complementary bevel gears 102 and 101. The rotation of bevel gear -1r11 causes bevel gears 1011 and l102 to be rotated in opposite directions so that each set of adjacent weights 85 and 86 are likewise rotated in opposite directions. By arranging the weights 85 and 86 ,in a manner such that all-of the weights are in their downward-most position simultaneously, rotation of the bevel gear 111 causes all of the weights S5 and 86 to rotate so that they all move into their 'upper-most positions simultaneously. It will be understood that alternate weights 85 are rotating in the same direction and valternate weights 86 are likewise rotating in the same direction and, d-ue to the fact that no two adjacent weights are rotating in the same direction, lateral forces,. which would otherwise tend to be generated by the weights, are automatically cancelled out, inasmuch as each of the weights has substantially the same mass as each other.

The oscillator driving shaft 110 is rotatably mounted by means of a plurality of bearings 112 respectively mounted between the cylindrical portion on the shaft 110 and within -a concentric telescoping sleeve member 113 disposed within the oscillator casing 21. The sleeve member y113 is held in iixed position within the casing member 21 by means of a vplurality of bolts 114 and a'turnedin flange portion 115 on sleeve member 113 spacer members 116 and i117 serve as a means for holding the bearings in axial position with respect to the sleeve 113. A spacer sleeve 118 rotates with shaft 110 in order to space the bearings 112 and the bearings 112 are held in iixed axial relation with respect to the shaft l by means of lan abutment shoulder 119 on shaft |110 and a nut 120vthreaded onto the shaft 110, as at 121. -In order to keep `dirt out of the space within sle'eve member 1-13, an annular member 122 is held in position with respect to casing member 122 having an axially extending radially inwardly disposed flange 123 immediately adjacent the relieved portion 124 of shaft 110. L

operatively interposed between the oscillator drive shaft 110 and the turbine assembly mounting shaft 30 is a planetary gear set 1125 which is adapted to establish an overdrive between the turbine shaft 30 and the oscillator drive shaft \110. 'I'he planetary gear set 125 comprises a ring gear 126 carried at one end of a cylindrical element 127, the latter being keyed by means not shown Aand splined onto a radially outwardly extending flange 128 formed on a collar member 129 which is |held in fixed axial position on the turbine shaft 30 by means of a lock nut 131 which is threaded onto a turned down end portion at shaft 30, as at |132, the lock nut 131 forcing the collar member 129 against an abutment shoulder 133 formed on the `end of threaded portion 34' of shaft '30; The ring gear 126 meshes with a plurality of pinion gears 134 respectively rotatably mounted on pinion carrier pins i135 which are carried by means of a planetary pinion carrier 136 which is integrally connected with members 22 and 17. Each of the pinion gears meshes with Va sun gear 137 which is splined to sh-aft 110, as at 138, the sun gear 137 having axially 'extending flange portions 139 for mounting ball bearing assemblies 140 between the `flange portions 139 and an annular race portion 1-41 formed on the inner periphery of carrier member 136. A Belleville washer member 142 Upon rotation of the turbine the ring gear 126 ro-l tates in the same direction and causes the pinions 134 to rotate lin the opposite direction, thereby driving the sun -gear 137 and shaft 4110 reversely at an overdrive.

Mounted above the oscillator casing 21 is an oil reservoir 146 which is secured to the oscillator housing -21 by means of a plurality of bolts 147. The oil reservoir 146 is formed with a cylindrical inn-er periphery i148 within which a piston member 149 having cylindrical sides 150 s reciprocable. The piston member -150 is formed with a pair of peripheral grooves 151 within which a pair of seal rings 152 are disposed. The cover portion 153 of the oil reservoir 146 has a central opening 154 within which drilling iiuid may enter in order to be impressed against the upper side of piston member 149. An oil conveying passageway 155 suitably connected to the lower end of oil reservoir 146 extends downwardly along the outside of oscillator casing 21,v

being held fixed thereagainst by means of a plurality of clips 156, and projects into a drilled aperture 157 in the upper end of member 17. The aperture 157 communicates with a plurality of drilled apertures `158, 159V the pressure head of the drill iluid is impressed against the top face of piston 149 and tends to compress the' serves as. one abutment for the bearings 11.2 whereas u piston against a supply of oil maintained in the reservoir t a pressure drop in the drilling mud fluid between thel reservoir 146 and the turbine assembly -15 and thus, the pressurized oil supplied to the annular cavity 162 which communicates with the sealing means 49 is at a slightly higher value than the pressure of the drilling mud uid being lay-passed through the orifice 81. Thus there is` always a pressure differenti-al against the face of optical llats 51, the pressure being greater in the oil than in the mud uid and the tendency, therefore, being for the i oil to leak slightly between the optically dat surfaces 52.

This, of course, is desired, as it is essential that the optical dats 52 be lubricated and itis further essential to keep the mud uid from entering the sealing means 49.

Inasmuch as the pressure within the cavity defined by. the oscillator casing 21 and within the space within which the planetary gearing 125 and the bearing assembly 26 are disposed is at a substantially lesser pressure than the pressure of the mud uid, for example, at atmospheric pressure or slightly greater, the relatively high pressure oil in annular ring 62 also tends to leak across optical ilats 51. This also is desired in order to keep the optical iiats properly lubricated.

The oscillator weights 85 and 86, the planetary gearing 125 Iand the thrust bearing assembly 2'6 must be lubricated and for this purpose a quantity of oil is introduced into the oscillator cavity. This oil tends to cling to the oscillator driving gears and weights and to thus be conveyed quite thoroughly through the oscillator cavity as well as around the planetary gearing and the bearing assembly 26. For the purpose of circulating the fluid lubricant within the oscillator chamber and over the planetary gearing 125 and thrust bearing assembly 26, a centrifugal pump device 163 is provided, the centrifugal pump device 163 being disposed beneath the bearing assembly 26 and around the abutment ring 32 and being adapted to receive uid lubricant as it drains olf of the bearing assembly 26, and pump the same radially outwardly into one or more fluid conveying passageways 164, from which it is conveyed through passages 165, 166, 167 and 168 into the region of the oscillator cavity within which pinion gears 98 and 99 are disposed. The oil thus supplied to the gears 98 and 99 is transferred from these gears to the successive oscillator driving gears 93 and 94 and a portion thereof passes downwardly through bearings 112 and into the planetary gearing 125 from which it can ow down directly through the bearing assembly 26.

When an earth bore hole is drilled by means of a sonic drill with which the present invention is utilized, the hydrodynamic load on the bearing assembly 26 is substantially constant irrespective of the depth of the well inasmuch as there is a substantially constant pressure drop across the turbine assembly 15. The load Iimposed on the bearing assembly 26 due to this hydrodynamic load is therefore substantially constant throughout the drilling operations and is always in a downward direction, the hydrodynamic load being represented by the line bearing this designation in Fig. 3. earth is hydrostatic loading on the bearing assembly 26 is substantially zero because of the fact that the height of the column of mud uid above the turbine assembly 15 is negligible. As the drill progresses into the earth as the bore becomes deeper, the hydrostatic load progressively increases, as the height of the column of drilling fluid above the turbine assembly 15 continuously increases with depth. Due to the fact that the turbine assembly 15 and bearing assembly 26 are disposed below the oscillator cavity within casing 21. the hydrostatic load on the turbine shaft 30 tends to force this shaft` upwardly thereby imposing an upward loading on bearfl ing assembly 26. This hydrostaticY load is represented At the surface of the 8 bythe line bearing this designation in Fig. 3` and such`` load constantly increases in an upward direction: i

The resultant loading on ythe bearing assembly 26 thus" represents the -algebraic sum of the hydrodynamic. load and the 'hydrostatic load irnposed'onf thebearing assembly 26 and is represented by the line designated as the bear-Y ing load in Fig. 3. lt is thereforeapparent that lat some substantial depth (quantitative values having not been given herein) 4then-actual bearing load on the bearing asf sembly 26 is practically zero, the bearing load above this point being in a downward direction due to the overbalance of the hydrodynamic load and the bearing load belowA th'ispoint being in an upward direction due to an overbalance of the hydrostatic load.

vObviously, by disposing the turbine Iassembly 15 beneath the oscillator assembly 16, it -is possible to obtain drilling depths of the order .of three times the depth which can be obtained with the reverse arrangement of the turbine assembly and oscillator assembly. -From the standpoint of the depth limitation due to the limit of thrust loading capable of being handled by the bearing assembly 26, this is a very important improvement as it has been found that the mere addition of more rows of bearings 27 or the utilization of larger bearing assemblies does not have very much effect on the ability of the bearing assembly to withstand substantially greater thrust loads of theorder of magnitude of say three times the hydrodynamic loading.

A further improved feature of the present invention results from the arrangement of the weights and 86, with the individual pairs of weights mounted on a single shaft being rotatable in opposite directions in order t0 further minimize or compensate for lateral forces which would otherwise be developed in the oscillator assembly 16.

From the foregoing description of the present invention it is apparent that numerous changes and modications may be made therein without departing from the scope of the present invention.

What is claimed is:

l. In an earth boring drill comprising an elongated massive longitudinally vibratory drill -rod having a bit at the leading end thereof and a supporting drill string, means forming `a part of said drill rod for vibrating the same and including oscillator means for vibrating the drill rod and turbine means for driving said oscillator means, said turbine means being. driven by pressurized drilling uid forced downwardly through passages in said drill `rod and drill string, said drill rod including means defining an oscillator mounting cavity disposed above said turbine means and substantially isolated from the drilling uid and at a substantially lower pressure than the pressure of the drilling fluid, a mounting shaft for said turbine means extending into the lower end of said cavity and connected to said oscillator means ,for driving the latter, sealing means disposed around said turbine mounting shaft forrmaintaining isolation between said oscillator v cavity and the drilling fluid, and bearing means mounted within said cavity for rotatably mounting said turbine shaft and adapted to resist axial thrust loads applied to said shaft, a hydrodynamic thrust load being applied to said turbine mounting shaft in a downward direction due to the pressure drop of said drilling fluid upon passing through the turbine means and a hydrostatic thrust load being applied to said turbine mounting shaft in an upward direction due to the height of the column of drilling uid above the turbine means, said hydrodynamic and hydrostatic loads acting on said turbine shaft in opposite directions vand thereby tending to compensate for each other and to minimize the axial thrust loading on said bearing means.

2. The combination in accordance with claim l and further including an oil reservoir and means defining oil passages for supplying oil to said sealing means torender the latter eiective to isolate the drilling fluid from said oscillator cavity.

3. The combination in accordance with claim 1 and further including pumping means driven by said turbine shaft for circulating iiuid lubricant to said oscillator means and bearing means.

4. The combination in accordance with claim 1 and further including pumping means disposed immediately beneath said bearing means and driven by said turbine shaft for receiving fluid lubricant as it drains from said bearing means and pumping the iiuid lubricant to said oscillator means.

5. The combination in accordance with claim 1 wherein said turbine means comprises a mounting shell secured to said mounting shaft by means of a web, and said web including means deiining an oriiice for by-passing a predetermined small portion of the drilling uid owing Ito the oriice therethrough for cooling said turbine mounting shell.

6. The combination in accordance with claim 1 and further including a uid lubricant reservoir disposed above said oscillator cavity and means defining lubricant passages for supplying lubricant to said sealing means to render the latter effective to isolate the drilling fluid from said oscillator cavity, said uid lubricant chamber including a reciprocable piston means therein responsive to drilling uid pressure for maintaining the pressure of the uid lubricant at a slightly higher value than the pressure of the drilling uid in the vicinity of said sealing means.

7. The combination in accordance with claim 1 and including a planetary gear set interposed between said turbine mounting shaft and said oscillator means for providing a ratio drive therebetween.

8. The combination in accordance with claim 1 and including a planetary gear set having an input member drivingly connected with said turbine mounting shaft and a driven member connected to directly drive said oscillator means, whereby a ratio drive is provided between said Eturbine and oscillator means.

9. The combination in accordance with claim 1 wherein said oscillator means comprises a plurality of pairs of rotatable weights, each pair of weights being oppositely rotatable about a common axis for minimizing or compensating for lateral forces developed during the rotation of said weights.

10. The combination in accordance with claim 1 wherein said oscillator means comprises a plurality of pairs 0f rotatable weights oppositely rotatable about a common axis, and successive pairs of said weights being longitudinally spaced in said oscillator cavity and having intermeshing driving gear means for simultaneously driving all of the weights.

References Cited in the le of this patent UNITED STATES PATENTS 1,482,702 Sharpenberg Feb. 5, 1924 1,526,748 Hermanl Feb. 17, 1925 2,554,005 Bodine May 22, 1951 2,592,519 Postlewaite Apr. 8, 1952

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