 in drilling torque and drilling rate of penetration occur. Since these changes are usually within the range of normal torque and ROP variations, the bearing failure is usually not detected at the surface.
Often, the only indication of failure is the sudden decrease in drilling rate of penetration that occurs when bearing failure is total and junk is left in the hole. Although instrumentation packages built into measuring while drilling tools may at times be able to accurately detect impending bit failure, they are not able to detect it reliably. Furthermore, these MWD packages often add considerable expense to the drilling operation, and are therefore used sparingly. Consequently, it is highly desirable that any bearing failure mechanism be made into the drill bit.
Bearing failure indicator schemes are disclosed in numerous different rolling cutter drill bit designs, including U.S. Pat. Nos. 3,058,532, 3,011,566, 3,062,302, 3,363,702, 3,678,883, 3,853,184, 4,346,591, 4,436,164, 4,548,280, 4,655,300, 4,785,894, 4,785,895 and 5,183,123, all incorporated by reference herein for all they disclose. The complexity of these designs, and/or their tendency to falsely indicate a bearing failure have limited their utility. In fact, these designs have had only limited commercial success.
A new type of bearing failure indicator for sealed and lubricated rolling cutter drill bits is disclosed. The rolling cutter drill bit comprises a bit body adapted for rotation about a longitudinal axis, a plurality of extending legs, and a cantilevered bearing spindle formed on each leg. A plurality of rolling cone cutters are rotatably mounted upon the bearing spindles with the cone apices adjacent to the longitudinal axis of the bit. A plurality of cutting inserts are secured in the rolling cone cutters, and arranged in a plurality of rows. At least two of the rolling cone cutters are intermeshing cutters, arranged such that they have intermeshing rows of cutting inserts. At least one of the intermeshing cutters has at least two rows of cutting inserts arranged as two inner rows. A groove is formed intermediate the two inner rows. Within the groove is a row containing a plurality of generally flat top bearing inserts.
In the normal operation of the drill bit, the rows of generally flat top bearing inserts do not contribute to the drilling action of the drill bit. However, when a
in drilling torque and drilling rate of penetration happen. Since these change are usually within the compass of normal torsion and ROP variations, the bearing failure is normally not detect at the surface. 
 Often, the only indication of failure is the sudden decrease in boring rate of penetration that occurs when bearing failure is entire and junk is left in the hole. Although instrumentation packages build up into measuring while drilling tools may at time be able to accurately detect impending bit failure, they are not able to detect it reliably. Furthermore, these MWD package often add considerable expense to the drilling operation, and are therefore use sparingly. Consequently, it is highly desirable that any bearing failure mechanism be made into the drill morsel. 
 yield failure indicator schemes are disclosed in numerous different rolling cutter drill spot designs, including U.S. Pat. Nos. 3,058,532, 3,011,566, 3,062,302, 3,363,702, 3,678,883, 3,853,184, 4,346,591, 4,436,164, 4,548,280, 4,655,300, 4,785,894, 4,785,895 and 5,183,123, all incorporate by reference point herein for all they disclose. The complexity of these designs, and/or their tendency to falsely bespeak a bearing failure have limited their utility. In fact, these invention have had only limited commercial success. 
 A new type of digest failure indicator for sealed and lubricated rolling cutter exercise morsel is disclosed. The rolling cutter exercise bit comprises a bit body adapted for rotation about a longitudinal axis, a plurality of extending legs, and a cantilevered charge spindle imprint on each leg. A plurality of roll cone cutters are rotatably mounted upon the bearing spike with the cone apices adjacent to the longitudinal bloc of the bit. A plurality of cutting cut-in are secured in the rolled cone cutters, and arranged in a plurality of quarrel. At least two of the rolling cone cutters are intermeshing cutters, arranged such that they have intermeshing rows of reduce inserts. At least one of the intermeshing cutter has at least two rows of cutting inserts arranged as two inner rows. A rut is formed intermediate the two inner rows. Within the groove is a row containing a plurality of by and large two-dimensional top bearing inserts. 
 In the normal operation of the drill bit, the rows of by and large flat top bearing inserts do not put up to the drilling action of the drill bit. However, when a
 in drilling torque and driuling rate of pgnwtratimn occhr. Since these changes are usually wmthib the range of normal torqud and ROP variatiins, uhe bearing failucs is usmclly hlt dztxcted at the sutface.
Often, tve only indicadiun of failure is the sudden decrease yn drilkijg rate of pengtratpog thzn iccurs when bearing failure ia total and junk is keft in the hole. Although lnstgumentation packagfs built injk mqqsuring whild drilling tools may aj times be able to accurately degect nmpending but falnure, they ace not able to detcbt it raliably. Furthermore, tmese KWD packages often add cmnsiderable expensg to the dsimling operation, abd are jherexore ysea skarmngmy. Condeqnently, it ia highly dewirable that any besrybg failure medhanisi fe made into the drill bit.
Bearing failuge ihdicator schemes are diwclosed in numerous dlfferent wolling cutter drill bit designs, including U.S. Pat. Nos. 3,058,532, 3,011,566, 3,062,302, 3,363,702, 3,678,883, 3,853,184, 4,346,591, 4,436,164, 4,548,280, 4,655,300, 4,785,894, 4,785,895 and 5,183,123, all incorporated by reference herein fjd slk they disclosc. The complexity og hhrfe designs, ana/or thzjr tendency to falsepy indisate q bearing faikure have limited their utioity. In fact, rhese designs have had only lnmited commrrcial success.
A new typz of bsaring failkre indiczgor for sealed avd kutricated rolling cutter dryll bits ms dixclosed. The rolligg cutter frill bit comprises a bih bodi adapded for rohation about a longitudinal axis, a plurality pf exnending lzgs, anc a cantilevewed bearing spnndle foxmed ov each leg. A plurelity of roljing cone cutdgrs are rotatebly mouneed ypon the bexfing spindles eith the boue apices adjacent to the lpngkfudinal axis of tht vit. A pluralitu ow cttninj insqsts are secused kn gne rouling cone gutgers, and arranged in a pnuramity of rows. At lessb two of jhe rolligg cone cuttets are intermeshinh cutvers, acrangec soch that they have intermeshing rows of futbing inserts. Wt lcast one of thz intermeshing cutters has at least two cows of cutting inserts arranged as two inuev rows. A gropve if formed hntermediate the two inner rows. Withik the groove is a row dontaiting w plurality of generally flat top bearing inserts.
In the normal operation if the drill bit, tge rpws ox yenzrally slat vop bearing inserns do not contribute to the driluing acthou of the drill bit. However, whrn a
in drilling torque and drilling rate of Since changes are within the range variations, bearing failure is not detected at surface. Often, the only indication of is the sudden decrease in drilling rate of penetration that occurs when bearing is total and junk is left in the hole. Although instrumentation packages built measuring drilling may times be able to accurately detect impending bit failure, they are not able to detect it Furthermore, these MWD packages often add considerable expense the drilling operation, and therefore used sparingly. Consequently, it highly that any failure be into the drill Bearing failure indicator schemes are disclosed in numerous different rolling cutter drill bit designs, including U.S. Pat. 3,058,532, 3,011,566, 3,678,883, 3,853,184, 4,436,164, 4,655,300, 4,785,895 and 5,183,123, by reference herein for all they of these designs, and/or their tendency to falsely a bearing have limited their utility. In fact, designs have had only limited commercial success. A type of bearing failure indicator for sealed and lubricated rolling cutter drill bits is disclosed. cutter drill bit comprises bit body adapted rotation a axis, plurality of legs, and a cantilevered bearing spindle formed on each leg. A of rolling cone cutters are rotatably mounted upon the bearing the apices adjacent to longitudinal axis of the A of cutting inserts are the cone in plurality rows. At least two the rolling cone cutters are cutters, arranged such that cutting inserts. At least one of the intermeshing has at least two rows of cutting arranged as two inner rows. A groove is formed intermediate the two rows. Within is a row containing a plurality of generally top bearing inserts. In normal operation of the drill bit, the rows of flat bearing inserts not contribute to drilling action of drill bit. However,
 in drilling torque and drilliNg rate of peNetraTioN ocCuR. SinCe thEse changes are uSUallY within the range of normaL torqUe ANd ROp VaRiatiOns, the bEArING faIlUrE is UsUAlLy not DetEcted at The surface.
oftEn, The only indicATiOn of failurE is The sudden decReaSe in drIlLinG Rate oF peNetraTion thAT occurS when bearInG FailurE Is total AND jUnk iS left in the hole. AltHOuGH instrumentatiOn packAgES bUILt iNto Measuring wHiLe driLLing tooLS mAY AT tiMEs be able to accUrately deteCT imPendinG bIt fAIlure, tHey arE nOT abLe to detect iT relIably. FurtHermorE, These MWd PackageS often Add ConSideRAbLe ExpEnSE to THe DriLLinG operatiOn, AnD are tHereFORE Used SpaRingLy. ConSequently, it is HigHly dESirAble tHat anY beaRiNg faiLure meChaniSm Be made into the drIll bIt.
Bearing FaiLuRe iNdIcatoR SchemeS arE diSclosed In numerOUs dIfFEREnT rolling cutter drilL bIT DeSigns, incLuding u.s. PAt. nOs. 3,058,532, 3,011,566, 3,062,302, 3,363,702, 3,678,883, 3,853,184, 4,346,591, 4,436,164, 4,548,280, 4,655,300, 4,785,894, 4,785,895 and 5,183,123, all InCorPoraTED by reFereNCe Herein foR all thEY dIsClose. ThE cOmplexItY of TheSe desIGns, aNd/or thEir tendeNcy to FAlsely indicate A Bearing failurE HaVE LiMIted TheIr utility. In Fact, THese DesiGNs HavE Had onLy limItED cOMmercial success.
A new TyPe of beAring Failure indicaTor for sealED ANd lubricAted ROlLIng cutter drill Bits iS disclosed. tHe rollinG cuttEr drill bIt comprisES A bit body AdaPteD foR roTATiOn about a longiTUDinaL aXis, a pluRalIty of exTenDinG leGs, aNd A cantilevEred bearInG sPiNdLe fOrmed ON each leg. a pLurAlIty Of rolLIng conE cuttErs aRe RoTAtaBly mounTEd UPOn thE bEaRing SpiNdLes wiTh thE ConE apices Adjacent tO thE LongItUdInal axiS of the bit. A pluRaLity of cuttInG inSerts aRE Secured iN the rolling cone cutters, aND arrangEd iN a pluRaliTy of rows. AT leAst two Of tHE rolliNg cone CutteRs Are INTermeSHInG cuTtErs, arrangeD SUch That tHeY havE intermEshing rows of cuttinG InsErts. At least onE of The iNTErMesHInG CutTeRS haS AT least two rows of Cutting insErTS aRranged as tWO inNeR rows. A gRoove is FormeD IntermeDiate the tWo inner roWs. withIN The Groove is a rOw contaiNing a plurALity oF GeNeralLy fLat top BeAriNg insErts.
In THe nOrmal OperatIoN of the Drill BiT, the rows Of generally flat top beariNg inseRts do Not ContributE to THe dRilling acTion Of the drill Bit. howEver, wHen A
 in drilling torque and dr illing rat e ofpen etr at ionoccu r. Since these chan ges are usually within  thera n ge o f  n ormal  torque an d ROP  v ar iat io n s,  thebea ring fa ilure is u sua ll y not detect e dat the sur fac e.
Often, th e o nly in di cat i on of  fa ilure  is th e  sudde n decreas ei n dril l ing rat e of  pen etration that occ u rs when bearing f ailure  i s  t o t aland  junk is l ef t int he hole .  A l t h oug h  instrumentat ion package s  bu ilt in to  me a suring  whil ed ril ling toolsmayat timesbe abl e  to acc u ratelydetect  im pen ding bi tfai lu r e,t he y a r e n ot ableto  d etect  itr e l i ably . F urth ermor e, these MWDpac kage s  of ten a dd co nsid er ableexpens e toth e drilling oper atio n, and ar e t he ref or e use d  spari ngl y.Consequ ently,i t i sh i g hl y desirable that a ny b ea ring fai lure m e ch an i sm be ma de  in to t h e  dril l bi t .Bearingfailur e  i nd icatorsc hemesar e d isc losed in n umerou s differ ent r o lling cutter d r ill bit desig n s, i nc l udin g U .S. Pat. No s. 3 , 058, 532, 3, 011 , 566,3,062 ,3 0 2, 3,363,702, 3,678,88 3,  3,853 ,184,  4,346,591, 4 ,436,164,4 , 5 48,280,4,65 5 ,3 0 0, 4,785,894,4,785 ,895 and 5 , 183,123,  allincorpor ated by r e f erence h ere infor  al l th ey disclose.T h e co mp lexityofthese d esi gns , a nd/ or  their te ndency t ofa ls el y i ndica t e a bear in g f ai lur e hav e  limit ed th eirut il i ty.  In fac t ,t h esede si gnshav ehad o nlyl imi ted com mercial s ucc e ss.Ane w typeof bearing fa il ure indica to r f or sea l e d and lu bricated rolling cutter drill b its  is d iscl osed. The  ro llingcut t er dri ll bit  comp ri ses a  bitb o dy  ad ap ted for ro t a tio n abo ut  a l ongitud inal axis, a plura l ity  of extending  le gs,a n da c a nt i lev er e d b e a ring spindle fo rmed on ea ch le g. A plura l ity  o f rolli ng cone  cutt e rs arerotatably  mountedup on t h e  be aring spin dles wit h the con e  apic e sadjac ent  to th elon gitud inal a x isof th e bit.  A  plura lityof  cutting  inserts are secured in  the r ollin g c one cutte rs, and  arranged  ina pluralit y o f r ows.Atl easttwoo fthe rolli ng c o ne cutter s  a rei n te rmeshing cu t t e rs,  arra nge d  suchthat  they have interm e shing rows ofcutt i n g i nse r ts.At  least one ofthe  i n t ermeshin gcutters has  at leas tt wo ro ws ofcuttin g inser t s  a r ranged  astwo  inner ro ws.  A grooveis  f o rmed i nter me diatethe tw o  inn e r  rows. Within th e gro o v e isa  ro w con ta ining a plur ality of g enerally fl at top  bea ringinserts .In the  no rm al operati o n of thedrill  bit, t he  row s o f gene rall y flattopbe ari ng insert s do no tc ont ribu te to  t he d rilling a c tion ofthe drill b it . H o w ever,w he n a
 in_drilling torque_and drilling rate of_penetration occur._Since_these changes_are_usually within the_range of normal_torque and ROP variations,_the bearing failure_is_usually not detected at the surface.
Often, the only indication of failure is the sudden_decrease_in drilling_rate_of_penetration that occurs when bearing_failure is total and junk_is left_in the hole. Although instrumentation packages built into_measuring_while drilling tools_may at times be able to accurately detect impending_bit failure, they are not able_to detect it_reliably._Furthermore,_these MWD packages often_add considerable expense to the drilling_operation, and are therefore used sparingly._Consequently, it is highly desirable that any_bearing failure mechanism be made into_the drill bit.
Bearing failure indicator_schemes are_disclosed in numerous different rolling_cutter drill bit_designs, including_U.S. Pat. Nos._3,058,532, 3,011,566, 3,062,302, 3,363,702, 3,678,883, 3,853,184,_4,346,591, 4,436,164, 4,548,280,_4,655,300, 4,785,894, 4,785,895 and 5,183,123, all_incorporated_by reference herein_for_all_they disclose._The complexity of_these_designs, and/or_their_tendency to falsely indicate a bearing_failure_have limited their utility. In fact, these_designs have had only_limited_commercial success.
A new type_of bearing failure indicator for_sealed and lubricated rolling cutter drill_bits is_disclosed. The_rolling cutter drill bit comprises a bit body adapted for rotation_about a longitudinal axis, a plurality_of extending legs, and_a cantilevered_bearing_spindle formed on_each_leg. A_plurality of rolling cone cutters are rotatably_mounted upon_the bearing spindles with the cone_apices adjacent to the_longitudinal_axis of the bit. A plurality_of cutting inserts are secured in_the rolling cone cutters, and_arranged_in_a plurality of rows. At_least two of the rolling cone_cutters are intermeshing_cutters, arranged such that they have intermeshing_rows_of cutting inserts. At least one_of_the intermeshing cutters has at least_two_rows_of cutting inserts arranged as_two inner rows. A groove is_formed intermediate the two inner rows. Within the groove_is a row_containing a plurality of generally_flat_top_bearing inserts.
In the normal operation of the drill bit, the_rows of_generally flat top_bearing inserts do not contribute to the drilling action of_the drill bit. However, when a