US2814462A

US2814462A - Fluid packed drill collar

Info

Publication number: US2814462A
Application number: US432570A
Authority: US
Inventors: Jarnett Frank D De
Original assignee: PAUL A MEDEARIS
Current assignee: PAUL A MEDEARIS
Priority date: 1954-05-26
Filing date: 1954-05-26
Publication date: 1957-11-26
Anticipated expiration: 1974-11-26

Description

F1. D. DE JARNETT yFLUID PACKED DRILL COLLAR Nov. 26, 1957 3 sheets-sheet 1 Filed 'May 26, 1954 m), MM M IN V EN TOR.

F. D. DE JAR'NETT FLUID PACKED DRILL COLLARA Nov. 26, 1957 5 Sheets-Sheet 2 Filed May 26, 1954 IN V EN TOR.

Nov. 26, 1957 F. D. DE JARNETT 2,814,452

' FLUID PACKED DRILL COLLAR Filed May 26, 19.54 3 Sheets-Sheet 5 l. L A mm1- ,Illy

fn/VK f bl/WYE?? INVENTOR.

rraP/VE/w direction.

United States Patent() Vthe rotary drilling bit lat the bottom of `the column commonly create suchstrainvand-fatigue the `metal of the drilling column as tocause structural failureorftwistoffs. The :failures occur latscrew threads whichrare .the `weakest vpoints in the drilling column. More `often ythan `not the failures occur in the lowerparttofthe .drill column but they mayoccur in drill vcollar threadsfortool joint threads at any rlevel.

rThe factors that determine the'ffrequencyand amplitude ofthe vibration and of the shock forces -include therate of rotation of the drilling'bit, the pressure applied 'to the drilling bit, the kind of Lformation encountered 'by the drilling bit, the slope offthelformation, etc. Usually `the forces involvedtend to -be excessive .as `the drillingbit makes the transition from one formation to another. Y

The rate of vrotation of the -drillingbitfmay vany lfrom 40 R. l. M. to 500 RF. M. or higher and, of course, vibration increases with the 4.speed of rotation. -fUsually a relatively high rate of vrotationiisfdesirab'le but yis not .permissible because .of the destructive effect of the re sultant vibration.

The pressure imposed on the rotary bit varies from 300 to 2500 lbsperfinch diameterof the hit.` YThusgthe total pressure varies from y1/2 ton .to l2`5 ftons. More than tons is .seldom'necessarv If the drilling bit pressure were obtained by placing most or all of the drill column .under longitudinal compression, the Yresult would :be :the .creation .of excessive and destructive stressesatethe .drill collarsand tool'joints in the drilling column. AAnd .afurtherresult would be the likelihood =of diverting `the .drilling from .the .desired For these reasons 'the\desired;pressure at the rotary bit is provided by-adding-weightftothe.lowerend of the drilling column. The`added weight is obtained by a drill collar assembly consistingtofwa .seriesof individual drill .collars substituted .for lengths `ofdrillpipe at `the ylower end ofthe drilling column. Such .individual drill collars lare usually made'.by..machining.and boring solid lengths of steel `to Yprovide.heav,y `tubes `with relatively ythick walls. Themachining, and .especiallythe boring, is expensive sothat'such individualdrillcollars are relatively costly items.

YTo avoid subjecting the drill pipe of V'the .column .to such excessive compressive stress with vresulting .fatigue and failure, the weight .onthe .rotary 'bit should never exceed that of the drill collar assembly and preferably should normally be not more "than'half'the vveightdfA the drill collar assembly. Thus allcompression'in'the drill column is lconfined "to the 'drill collar 'assembly 's'o :that the major portion of the 'drillco'lumn is under -tens'ion rather than compression in "the drillingffofa deep fwell.

It is apparent that the drill collar assembly will=usually have considerable weight.l A drillfeollar assembly as ylong as 180 feet and weighingias'QrinlchA astS tonslisfnot unusual.

In some 'types tof formations, rsuehffas v:brittle rshales,

4gumbos J and conchoi'dalffracturing flimestones, f there is 11a denite upper -limit-ato A:the 'rbitg pressure that can .be used efliciently, higher bit pressures reducing the rate of ICC 2 penetration. More rOften than not, however, there is reason to use Ya relatively high bit pressure along lwith a `relatively vhigh rspeed of rotation. 'Thus in some formations, such as limestone developing angular fractures, salt, very hard sandstones `or quartzites, and igneous rocks, "the rate of penetration ofthe bit appears 'to increase as a straight line function 'with increase Ain bit pressure, irrespective Vof the rotating -speed and volume of fluid cirlculated. Again in other y'formations such as soft sandstones, sandy shales and silts, vthe rate lof penetration rincreases directly with weight on the bit if uid circulation and rotational speeds are proportionately adjusted.

lSome of the ycauses #of vibration and shock may be readily understood bymconsidering -the manner in which a drilling bit functions. At the proper bit pressure the Jdrilling bit fembeds itself in the formation just enough to --permit it to chip away the `rock yin small fragments =as fthe stem revolves. inevitably, however, situations arise and persist lfor periods of .time in which the bit pressure is excessive for the particular formation. In 1that event, Ythe bit'will embed itself in the rock to such extent that it `cannot `cut itself free. lSince the drilling bi't cannot -cut zitself vfree it repeatedly jumps loose to ycause a chattering action that strains the whole equipment. The tremendous weight .of -the usual drill collar fassem'bly 'is added to this chattering action. It is this kind of vstrain that commonly `causes twistoffs with the lpenalty of added 'labor `and lloss of drilling time. To :avoid :such consequences :drillers are vcommonly forced -to :be vvery :conservative -in drilling -speeds and pressures.

The 'presentinvention alleviates Vthe eifects of vibration, '-.c'hatter, and :other forces generated at the drill bit, by .providing .fa drill collar'constructionwhich will 'cause such forces to "beatleast partially dampened anddissipated at tthelower end of thedrilling column. It is contemplated .that'each individuahdrill 'collar in the series of drill collars will labsorb a tportion of the forces transmitted thereto from below so :that the Aseries=ofldrill collars in the drill "collar assembly vwill have :a desirable cumulative effect on `the engendered forces.

In .general Jthe fdesired'eifect is attained by mounting :masses ofm'aterialfon the lower `end of the drill column withfreedomforlmovementof themasses relative to the drill fcolumn. Energy-isdiverted from the solid structure` fof the drill column by transmission'lto these masses of material to cause independent-movement thereof. Energy fis'dissipated, in part, byfriction involved in 'the relative Vm'ovements of the added masses. Energy' dissipation also A.arises yfrom the 'fact that the -masses being largely free from .controlmove yat random relative yto the solid structure of the drill column, so that a vibratory or shock Vmovement of thexdrillcolumn structure-in one longitudinal =directi`on lmay .result in .an impact against a free mass Ymoving-.inthe opposite direction, energy being absorbed advantages @peculiar Ito .each.of.the .twot kinds of material,

but also provides a certain dashpotaction in the inter- .ference .by .the .liquid with* the .movements of .the solid material.

The solid material in the various practices of"thein vention may comprise a small number of relatively large solid bodies or a large number of relatively small solid bodies and may even comprise finely divided solid material. An important advantage of combining liquid material with solid material is that it makes it possible to cause the Solid material to seek any desired normal position within its range of vertical movement.

lf a liquid is selected that is of lower specific gravity than the solid material immersed therein, the solid material will seek a normal position at the lower limit of its range of relative vertical movement. ln such an arrangement the solid material responds primarily to upward components of movement of the drill column and has maximum freedom for upward movement in response to such upward components. lf the liquid is selected for a higher specific gravity than `the so-lid material to cause the solid material to lloat thereon, the solid material may be caused to seek a normal position at the upper limit of its range of relative vertical movement. Thus the solid material will respond primarily to downward components of movement ot the drill column and will have maximum freedom for movement in response to such downward component.

it the liquid has a higher specific gravity than the solid material, the volume of the liquid relative to the volume of the coniined space and the volume `of the solid material may be selected to cause the solid material to tend to oat at any desired intermediate level in its range of relative movement. The solid material will then have freedom for vertical movement in both directions from its normal position and will not make direct impact with the solid structure of the drill column unless it reaches one or the other of the two limits of its range of vertical movement.

lt is apparent that a drill collar assembly made up of a series of individual drill collars may comprise a variety of individual drill collars for a variety of individual eteets. Thus in some drill collars of the assembly masses of solid material will normally seek the lower limits of their ranges of movement; in other drill collars of the assembly, the masses of solid material will normally seek the upper limits ot' their ranges of movement. In any event, a drill collar assembly incorporating relatively movable masses of material in accord with the teachings of the invention will absorb, dissipate and dampen vibratory forces and shock forces to minimize the structural failures that are commonly caused by vibration and shock. Such a drill collar assembly will permit a higher than usual rate of rotation of the drilling bit with consequent higher than usual rate of penetration by the bit.

The various features and advantages of the invention may be readily understood from the following detailed description considered with the accompanying drawings.

in the drawings, which are to be regarded as merely illustrative:

Fig. l is a simplified diagrammatic view of a drill column in a bore hole with the lower end of the drill column provided with a drill collar assembly as taught by p the present invention;

Fig. 2 is an axial section of a portion of the drill collar assembly in Fig. 1 showing the construction of an individnal drill collar in the assembly;

Fig. 3 the line 3-3 of Fig. 2;

Fig. is a view, partly in side elevation and partly in section, showing a `second form of individual drill collar that may be used in the drill collar assembly;

Fig. 5 is a transverse section taken as indicated by the line S- of Fig. 4;

Fig. 6 is a view similar to Fig. 4 showing athird form of individual drill collar that may be used;

Fig. 7 is a similar view showing a fourth form of drill that may be used;

is a transverse section taken as indicated byK Fig. 9 is a similar view of a still further form of drill collar construction that may be used; and

Fig. l0 is a transverse section taken as indicated by the line 10-10 of Fig. 9.

Fig. 1 shows schematically an oil well bore 20 in which a drilling string or drill column 2 carrying a drilling bit 22 is rotated in the usual manner by the rotary table 23 of a drilling unit at the top of the well. The lower portion of the drill column 21 comprises a drill collar assembly, generally designated by numeral 24, which, in turn, comprises a series of individual drill collars 25. Any number of individual drill collars 25 may make up the drill collar assembly 24, the number being determined by the weight that is desired on the drilling bit 22.

Fig. 2 shows one embodiment of an individual drill corlar, generally designated 25a, which may be incorporated in the drill collar assembly 24 of Fig. l. The construction shown in Fig. 2 includes an inner steel tube 3d and a shorter outer steel tube 31 which together form an annular space or chamber 32. As best shown in Fig. 3 a series of I-beams 33 may be positioned longitudinally in the annular space 32 to serve as spacers and to provide reinforcement for the two tubes. The I-beams 33 may be attached to the inner steel tube 30 by welding.

The upper end of the inner steel tube 3i) is threaded into a tool joint box 35 in a fluid tight manner. The iluid tight fit may be accomplished by threading the inner steel tube 30 in to the tool joint box 35 while the tool joint box is heated so that the tool joint box will shrink into a pressure t with the inner steel tube. United with the tool box joint 35 by welding 36 is a sleeve extension 37 which embraces the inner steel tube 30 and is attached by welding 40 to the upper end of the outer steel tube 31 to close the upper end of the annular compartment 32. In the construction shown, the sleeve extension 37 has an end portion 41 of reduced diameter to t into the end of the outer steel tube 31. The end of the outer steel tube 31 is bevelled as shown to permit the welding 40 to lie inside the desired maximum diameter.

In like manner the lower end of the inner steel tube 3i) is threaded into a tool joint pin 44 in a iiuid tight manner. Connected with the tool joint pin 44 by welding 45 is a sleeve extension 46. The sleeve extension i6 has a reduced end portion 47 that tits into the lower end of the outer steel tube 31 and is attached thereto in a uid tight manner by Welding 48 to form the lower end of the annular chamber 32.

It is contemplated that the annular chamber 32 will be partially lled with a suitable liquid in addition to containing the I-beams 33. Any suitable arrangement may be provided to make it possible to introduce liquid into the annular chamber and to drain the liquid out of the chamber when desired. For this purpose each of the two

sleeve extensions

37 and 46 may have a short longitudinal bore 50 communicating with a radial bore 51 to provide a passage for communication between the annular chamber 32 and the exterior. The two radial bores 51 may be closed with suitable screw plugs 52 to connc a body of liquid in the annular chamber 32, Pref erably the liquid level is slightly below the upper end of. the annular chamber 32, for example, as indicated at 55, to provide room for thermal expansion of the liquid.

Any suitable liquid may be used, including relatively heavy liquids as well as relatively light liquids. For example, the liquid may be mercury, oil or water. ln some instances it will be desirable to use a relatively light fluid having a low freezing point, for example, glycerine or alcohol.

If the annular chamber 32 contains mercury the total weight of the individual drill collar 25a including the mercury will be of the same order of magnitude as the Weight of a conventional solid steel drill collar but the freedom for movement on the part of the confined mercury body will provide a desirable damping effect on faisaarea the mercury. l`Downwarn movements :of [the erin cenar engendered fb'y the 'drill bit, however, fare fnotopposed by the ittljhe'rti'a lof the mercury fbdy because libere :is fredonljfdr relative vertical movement 'between iure 'meriiiiy lbod-y an'd 'fth'e confining structure fof 'the Sdr'ill collar.

In afdoivnwardmovemeiit of lthe drill column "thec'o'n- #lined 'r'ne'rcry body ten'ds lto romain fstationary but 'this ftnd'ency is opposed fby Jthefr-iction between the mercury fanti the *vertical inetalsurfac'e's including :the imany vertical fsufaces -of the vlI-ibeams :33. :In addition `the tende'r'ioyfo'rthefmrcy Abody torernain stationary when the 'drill column "1i-loves vertically vdownward l-is opposed by the-air body linithe ich'ainbe'r 32 above the =liquid level of fthe mercury "It `lis apparent fthat 'when :the vlmercury colilnih Iin lthe"cliainber 32is ylifted bodily by an upward `tli`ru`s of'tlie drill-column andtlielupwardf-thrust is-abrupt- '1l-y terminated, 'the 'mercury will tend to continue its `up- -w'a'cllmove'ment 'and will 'be fdeceler'ated by -frictio'naltrefs'istan'ceandf-by'displacementfof the 'air body and impact `o'f the 1'nrc1'1`ry fagainst the upper end lsurfaces of `the fenaniberlsz. g

"lliref'inof course, -a slight delay'involved'with respect to -th'e iiinpact of ftherne'rcury 'bodyagainst the upper 'end lwallffthechaniber. 72VIf theldrill column is vibrating, the 'fviliratbryu'pward thrust AWof the drill column 'will 'be followedl immediately by a downwardth'rusta'nd'thefimpact of the r'nercury against `the upper =end wall of the cli'amb'erinayoccur at 'a time'to oppose'the downwar'dfmove- 'ine of `the "drill column. Thus, more -often tha`n fnot, T`th`e mercury lwill oscillate' out` of phase 'with respect to the 'v'erticalfvibrator'y movementof thefdrill coluninj the outzof lphase r"relationship providing -a desirable 1 damping action.

Theindividual drilll'collar 25h shown iin Figs. 41' and y5 isfl'argely'id'entical with the f lirstdescribed embodiment/as indicatd'by the use of corresponding nme'ralsuto indicate 'correspontlingl'parts. VIn this second-embodiment'iof the invention the flibe'ams vare'omitted andthe annular cham- IAbei' TST-ofthe drillfcollar structure 4is occupied bya single "solid lmetal body together Ywith a body vof mercury in which the solidbodyisfatileastpartiallysubmerged. The Isolidlr'netal'bodyiisfin vthe'fo'rm of heavy `tubular membe1"60,whichmay'be a heavysteeltu-be dimensioned yfor :free longitudinal \moverne`rit `in 'the annular chamber 32. The 'heavy Psteel ytubular `body'60 'is immersed in 'ia =body 61 lof mercury and tendsito float Ton the mercury body.

vinercuryfmay Yextendtoa liquidil level 62, A1for ex- F-anple," whichfis at'a sulficientfe'levationto zh'old thetbular body 60 against the upper end of the-chamber-32 '.understatic conditions. It `will be notedthat-therens a `^substantial;airspace above tlie vliquid leve1 62 vlwhich=not only allows for thermal expansion of-the-tubula'r body andof'themerc'ury bodyi' 61, but also=provides space 4for f'surgin'g 4#action of 'the mercury.

fi'Si'nce' the `metal tubular body 60v is normally in'- contact with the upper'end f theannularechamberzlitiis apiparentthttlie tubular body 60 `will respond directlyand ib'odily todownward thrusts offthe'drill-column;and?itis further apparent that there is room for a substantialrange tofrelative'downward movement of thetubular--body 60 from its `normal `static vposition relative to the structure of the drill column. y

Downward movement of the tubular metal body 60 relative tothe-drill columnvis opposed,vrst, by the tendency of the tubular body to float and, second, by the resistance of ythe mercury toupward Ydisplacement through tlie narrow longitudinal spacesinsidecand Outside "o'f the "itubulr bo'dy 60. There is a certain'dashpot/actionlin- 'volvedlin' the restriction of-the upward "ow o`f"the"m`er -cury.

-It is lapparent that an abruptly 'terminated' downward 'thrust-on'the-part-of the drill column will result inVcontinued vdownward "movement of the solid -tubular 'bodyf60 zinfannular chamber with consequentdisplacement'otfmercury and `that the solid tubular body will 4then seek fto return lto its normal upper floating position. The #solid tubular `body returns toits normal upper position afte'r an appreciable time delay and `in 'nany Vinstances lthe solid tubular body will make thisfupward returnimovement-in synchronism with a downward tlir'ustiof the drill column to oppose the ldownward thrust. Thus, =here again, the freedom for a relatively :movable mass of material to reciprocate out of phase lwith lthe longitudinal reciprocation of thedrill column is importantin modifyying the action of the drill column by dampingleffectsand energy dissipation.

The third form of fthe linvention comprising -thein'dividual drill collar 25c'shown'in Fig. f6 `is `identical with ythe form shown in Fig. 4 as indicatedby the'u'se of-identical numerals to designate identical parts. -In .this -instance, however, the bodyof mercuryis'replaced-by-a body 66 of relatively light lliquid, for example, Water, which liquid has a normal static ylevel 67. Since .the liquid is-of much lessfspeciiic gravity than-the solidtubular body60, the tubular'bodynormally seeks a position Aat the Vbottom of the annular chamber 32 as 'lshown'in Fig. 6.v There is freedom for relative movementlof the body of liquid 66 because the normal liquid level 67 -isvspacedsubstantially below the upper end of the annular chamber.

In the embodiment of the invention; shown in Fig. V6, the solid tubular body 60 responds directly Dto 'upward thrusts of the drill column and has a rangefor-relative upward 'movement in response to such thrusts. vThe `upward movement of the solid tubular body -60 is opposed bygravity and by frictional resistance. lIt is also Atube `noted that any upward movement of the solid tubularbody 60 that contracts the space abovey thenormal'level 67 will be opposed by the compression of air -body therein. f 4desired this air may be normally under ypressure substantially-above atmospheric.

If lthe relative upward movement of the solid tubular -body 60 in the -annular -chamber -32 results in downward displacement of the liquid into ythe lower end of the chamber, there will be a certain dashpot action to resist both the relative upward `movement and the return downward movement of the solid tubular body since -the liquid is forced through restricted longitudinal spaces inside and outside lof the solidtubular-body. Here again it is apparent'that the freedom for the 4'solid tubular body 60 to reciprocate vertically out of. phase with the vertical reciprocations of the drill columnis important.

Fig. 7 shows another embodiment of the'inventioncomprising an individual drill collar V25d which :is identical with the previously described individual drill collar'ZSb of Fig. 4 except for the quantity of mercury employed. In Fig. 7 the body of mercury A'l0 is of'less quantity than the body of mercury 61 invFig. 4, being'at-alowernormal liquid level 71 so that the solid tubular lbody A60m Fig. 7 v has a normal oating position intermediate the two ends of the annular chamber 32. Thus at the normal position of the solid tubular body 60 in Fig. 7 the solid tubular body has freedom for verticallongitudinal movement in both directions. Itis apparent that vertical movements of the drill column of relatively low ymagnitude will merely cause the float 60 in Fig. 7 to bob up and down without the iloat reaching either end of `theaunular space.y This bobbing action will beresisted by inertia, friction and by a dashpot action, all of which vtend to modify vibratory and shock forces in a desirable lmannen Vertical movements of the drill column of rel-ative large amplitude will cau-se thesolidtubular body y60 of Fig. 7 to reach one'or bothends ofthe annular chamber 32'to make impact against the solid structure of the vdrill column. n

The individual drill collar 25e shownV in Fig. 8- isof the same construction as heretofore described exceptfor the ""contentsoffthe annular cha-mber-32. flnthsinstance, the

annular chamber 32 contains a mass 72 of solid material in the form of relatively small bodies. The mass 72 may comprise, for example, relatively small steel balls. This mass 72 of bodies of solid material is immersed in a liquid body 73 of relatively low speciiic gravity, for example, water, the liquid body having a normal level 74 spaced substantially below the upper end of the chamber.

This embodiment of the invention shown inFig. 8 operates in much the same manner as the embodiment shown in Fig. 6, since in both instances a mass of solid material is normally at the bottom of an annular chamber containing a liquid. It is to be noted, however, that when such a mass of small bodies is thrown upward from the bottom of the annular chamber, the individual bodies of the mass tend to `separate so that the return impact of the mass against the bottom of the annular chamber is attenuated less severe than the sharp return impact of a solid body. Another difference is that the mass of small bodies forms numerous tortuous passages for relatively great resistance to displacement tlow of the liquid when the mass shifts vertically in the annular chamber.

The liquid body 73 may be omitted in the form of the invention shown in Fig. 8 if desired. It the liquid is omitted the individual bodies making up the mass of solid material will still tend to separate when the mass is lifted from the bottom of the annular chamber. Here again, the return downward movement of the solid material will result in less severe impact against the lower end of the annular chamber than would occur if the solid material were all in` one piece.

The individual drill collar ZS of Fig. 9 is similar to the individual drill collar of Fig. 8 but in this instance a mass 80 of small solid bodies for example, steel balls, floats on a body of mercury having a normal liquid level 81. In this instance, the liquid level is high enough to force the mass 80 against the upper end o the annular chamber 32. Thus the arrangement shown in Fig. 9 is the reverse of the arrangement shown in Fig. 8 in that the mass of small bodies responds primarily to downward thrusts on the part of the drill collar instead of upward thrusts. The same dashpot effect is present in both Figs. 8 and 9.

It is apparent that a drill collar assembly such as the drill collar assembly 24 of Fig. l may comprise a variety of individual drill collars 25, the variety including any of the individual drillcollars shown in Figs. 2, 4, 6, 7, 8 and 9 or similar individual drill collars. For example, a drill collar assembly 24 may include the individual drill collars 2511, 25o and 25d of Figs. 4, 6 and 7 respectively. Thus in some of the individual drill collars such as the individual drill collar shown in Fig. 4, the relatively movable material will respond primarily to downward thrusts of the drill column; in other individual drill collars such as the individual drill collar shown in Fig. 6 the relatively movable material will respond primarily to upward thrusts of the drill column; and in still other individual drill collars such as the` individual drill collar shown in Fig. 7 the relatively movable material in Seel/.ing a normal intermediate position will have a relatively mild and yielding action with respect to low amplitude movements of the drill column but will fully oppose movements of relatively large magnitude. The individual driil collars of Figs. 8 and 9 may be added to such a drill collar assembly or may be substituted for individual drill collars of Figs. 6 and 4 respectively. As heretofore pointed out, the individual drill collars of Figs. 8 and 9 operate with less violent impact of the solid material against the ends of `the annular chambers and in addition are characterized by a modified dashpot action.

My description in specic detail of selected practices of the invention will suggest various changes, substitutions and other departures from my disclosure that properly lie within the spirit and scope of the appended claims.

I claim:

l. A drill collar for connection between upper and lower portions of a drill column, said upper and lower portions extending upwardly to a rotary table and downwardly to a drill bit, respectively, said drill collar both providing weight for downward pressure on the drill bit and for minimizing the transmission of vibration and shock forces from the drill bit to the drill column, said drill collar comprising: inner tube means having a longitudinal tlow passage for communication with the drill column, upper coupling means ixed to the upper end of said inner tube means and adapted for connection with the lower end of said upper portion of said drill column, lower coupling mean-s fixed to the lower end of said inner tube means and adapted for connection with the upper end of the lower portion of said drill column, outer tubular means having an upper end also connected to said upper coupling means and having a lower end connected to said lower coupling means, said outer tubular means surrounding at least a portion of said inner tube means and being spaced a predetermined distance therefrom to form a chamber therewith, a passageway extending from the exterior into the interior of said chamber, said chamber containing a selected medium comprising at least a liquid, said liquid `only partially lling said chamber, means to provide a liquid-tight seal for said chamber including means to seal said passageway, whereby vibratory and shock forces transmitted to said coupling means will be at least in part transmitted to said medium, the turbulence of said liquid created by the liow thereof in said chamber thereby dissipating at least some of the energy of said vibratory and shock forces.

2. The invention as defined in claim 1, wherein said selected medium comprises both a liquid and solid material, the specific gravity of said solid material being difterent from that of said liquid material, whereby vibratory and shock forces transmitted to said coupling means will be at least in part transmitted to said solid material and to said liquid material for movement of one relative to the other and independently of said coupling means, the turbulence of said liquid material created by the flow thereof past said solid material thereby dissipating at least some of the energy of said vibratory and shock forces.

3. The invention as defined in claim 2, wherein said solid material is a single solid body having a shape to permit its movement vertically in said chamber.

4. The invention as defined in claim 2, wherein said chamber is an annular chamber, and wherein said solid material is a hollow tube to tit in said chamber but being spaced at least from one of the means defining said chamber and being vertically movable therein.

5. The invention as defined in claim 4, wherein said solid material has a specific gravity less than that of said liquid material.

6. The invention as defined in claim 4, wherein said solid material has a specific gravity greater than that of said liquid material.

7. The invention as defined in claim 2, wherein said solid material includes a plurality of particles, the maximum dimension of each of which is small in comparison to the size of the dimensions of said chamber.

8. The invention as defined in claim 7, wherein said solid material has a specific gravity less than that of said liquid material.

9. The invention as defined in claim 7, wherein said solid material has a specific gravity greater than that of said liquid material.

References Cited in the file of this patent UNITED STATES PATENTS 331,450 Rothe Dec. 1, 1885 1,314,005 Louden Aug. 26, 1919 1,785,559 Ponti Dec. 16, 1930 2,025,100 Gill et al Dec. 24, 1935 2,126,075 Wright Aug. 9, 1938 2,712,435 Allen Iuly 5, 1955