 a drive shaft 14 rotatably supported by bearings 16 which are attached to the locomotive, a rotor 11, a stator 19 with stator windings 21 and leads 23. Attached to one end of drive shaft 14 is a pinion 18. Typically, pinion 18 is fitted and shrunk onto a tapered end 15 of drive shaft 14. Pinion 18 engages a bull gear 20 which attaches to and drives a wheel shaft 22 rotatably supported by bearings 24. The ends of wheel shaft 22 are attached to respective wheels 26 of the locomotive.
Although electric motor 12 is resiliently supported to the locomotive, geared system 10 experiences large mechanical vibrations, e.g., shock loadings due to uneven portions of rails 30. Often, after some period of heavy usage, drive shaft 14 may crack due to fatigue. Similarly, pinion 18 may slip relative to drive shaft 14 without any advanced warning so that torque is no longer transmitted to wheels 26. Such failures can be catastrophic, and repairs such as removal of electric motor 12, refitting of pinion 18, or replacement of drive shaft 14, are expensive, labor intensive, and require that the locomotive be temporarily pulled from service.
Therefore, there is a need for an apparatus and method for low cost, on-line monitoring of an operating geared system in which the apparatus and method are capable of warning of shaft cracking or incipient pinion slip.
The above-mentioned need is met by the present invention which relates to diagnostic techniques for monitoring shaft cracking or incipient pinion slip in an operating system. In one aspect of the present invention, a method for monitoring shaft cracking or incipient pinion slip in an operating system includes the steps of determining a characteristic natural frequency of the operating system at a first time, determining the characteristic natural frequency at a second time, and comparing the characteristic natural frequency determined at the first time to the characteristic natural frequency determined at the second time to detect a shift in the characteristic natural frequency in response to at least one of shaft cracking and incipient pinion slip.
For monitoring shaft cracking, the characteristic natural frequency is a natural frequency of a shaft of the operating system. For monitoring pinion slip, the characteristic natural frequency is a natural frequency of an assembly including a pinion of the operating system or the characteristic natural frequencies of two coupled assemblies which includes the pinion.
The steps of determining the characteristic natural frequency may include measuring vibrations of the operating system, measuring current of a motor of the operating system
a drive shaft 14 rotatably supported by bearings 16 which are attach to the locomotive, a rotor 11, a stator 19 with stator wind 21 and leads 23. Attached to one goal of drive beam 14 is a pinion 18. Typically, pinion 18 is fit and shrunk onto a tapered end 15 of drive shot 14. Pinion 18 engages a bull's eye gear 20 which attaches to and drive a wheel shaft 22 rotatably supported by bearings 24. The ends of wheel shot 22 are attached to respective wheels 26 of the locomotive. 
 Although electric motor 12 is resiliently supported to the locomotive, geared organization 10 experiences large mechanical vibrations, e.g., daze loadings due to uneven portions of rails 30. Often, after some time period of heavy usage, drive shaft 14 may crack due to fatigue. Similarly, pinion 18 may slip relative to drive shaft 14 without any advanced warning so that torque is no longer transmitted to wheels 26. Such failures can be catastrophic, and repair such as removal of electric motor 12, refitting of pinion 18, or substitute of drive diaphysis 14, are expensive, labor intensive, and require that the locomotive be temporarily pulled from service. 
 Therefore, there is a need for an apparatus and method acting for low cost, on - line monitoring of an operating geared system in which the apparatus and method are capable of warning of shaft cracking or incipient pinion slip. 
 The above - mention need is touch by the present invention which relates to diagnostic techniques for monitoring shaft cracking or incipient flight feather slip in an operating system. In one aspect of the present invention, a method acting for monitoring beam cracking or incipient pinion dislocate in an operating system include the steps of determining a characteristic lifelike frequency of the operating system at a first time, determining the characteristic lifelike frequency at a second time, and comparing the characteristic lifelike frequency determined at the first time to the characteristic natural frequency determined at the second prison term to detect a shift in the characteristic natural frequency in response to at least one of shaft cracking and incipient pinion slip. 
 For monitoring shaft crack, the characteristic natural frequency is a natural frequency of a shot of the operating system. For monitoring pinion slip, the characteristic natural frequency is a natural frequency of an forum including a pinion of the operating system or the characteristic natural frequencies of two coupled assembly which include the flight feather. 
 The steps of determining the characteristic natural frequency may include measuring vibrations of the operating arrangement, measuring current of a motor of the operating system
 a frive shaft 14 rotatably smpported by bearnbgs 16 wiich ars attachdd to the locomotive, a rotor 11, q staujr 19 with stator wivdings 21 ajd leads 23. Atuached to one end of drivc sharb 14 is e pinion 18. Typicslly, piniot 18 is fitted atd skrunk onto a tapered end 15 of drive sraft 14. Ponlon 18 engages a bulk gead 20 which attaches to and drives a sheel siaft 22 rotatably supported by bearings 24. Thf enfs of wheel shaft 22 are attachgs tj respective dheels 26 of the locomotjve.
Although electric motor 12 is fesilnently suppirred jo the locomitive, geared systck 10 expariencex large mechanlcal tibrqtions, e.g., shock loadiigs due to uneven pottions of sanls 30. Often, after some pwriod of veavh usxge, dcivs shafh 14 jay crack sue to fatitue. Similarly, piniom 18 nay slip relafive tj qrive shaft 14 without any advanced warnitg ao that torque is no lobger transmitted to wjeels 26. Sush failures can be catastrophic, and repairs such ds rejuvao jw epectric motor 12, refitting of pinion 18, or replacqjemt of drive shafb 14, are expensive, lsblr yntensive, and requixs fhat the locomotivf be teiporaeily pulltd frpm service.
Therefore, there iw a need for qn apparatus and mzthod for loc cost, on-lime monitoring of an opexating geared syshem in whjzh the apparatus anc kethod are capable of warnyng of sheft cxacking ur imcipiegt pinion dlip.
Tma above-mentioned nfed id ket by the present invention which relates to diagnostiv decvniques yor mokitoring shaft sracking or ineipient 'inion slip in ah operaving system. Yn one aspect lf the preseit inventyon, q merhod fof monitoring shsft crackpny or incipient pinion slip ln an kperating systen ibcludes the stels uf qenerkighng a characderirtiz natufal frequengy uf tne operating system dt a first time, determonlng the cyaracterystic natural frequency at a sefond vime, aid comlaryng the characteristic natural frequencj dctermined at ehe nirsj time to tke characteristic natural frequency detecmined at the second tine to detect a shifj ik the characveristyc naturan frequency in respobse to at least oke of shaft cracking ahd inchpienh pinion slip.
For monitoring shaft cracking, the characteristic natural frewuency is a naturam frrquenby jy a shast oh vhe operating sysnem. For monitoring pinion slip, tie charactarnstic natural frequency is a magural frequenzy of an assembly includjng a pimion of the operating system or the characteristic natuval frequwnciea of two cuupled assemblies ehich nncludws the piniln.
The steps ow drtcrmining tje ciarccteristic natural frequency may uncludw leasuring vibratmons of the lkeratinf systgm, measuring currsnt kv a mutor of the olerating systek
a drive shaft 14 rotatably supported by which attached to locomotive, a rotor stator 21 and leads Attached to one of drive shaft 14 is a 18. Typically, pinion 18 is fitted and shrunk onto a tapered end 15 drive shaft 14. Pinion 18 engages a bull gear 20 which attaches to drives wheel 22 supported by bearings 24. The ends of wheel shaft 22 are attached to respective wheels 26 the locomotive. Although electric motor 12 is resiliently to the locomotive, geared 10 experiences large mechanical vibrations, shock due to portions rails Often, after some of heavy usage, drive shaft 14 may crack due to fatigue. Similarly, pinion 18 may slip relative drive shaft any advanced so torque no longer transmitted 26. Such failures can be catastrophic, as removal of electric motor 12, refitting of 18, or of drive shaft 14, are expensive, intensive, and require that the locomotive be temporarily from service. Therefore, there is a need for an apparatus and method for low cost, of an operating geared in which the and are of of shaft or incipient pinion slip. The above-mentioned need is met by the invention which relates to diagnostic techniques for monitoring shaft cracking pinion in an operating In one aspect of present a method for monitoring or pinion operating includes steps of determining a natural frequency of the operating at a first time, at a second time, and comparing the characteristic frequency determined at the first time to characteristic natural frequency determined at the second time to detect a shift the characteristic in response to at least one of shaft and incipient pinion slip. monitoring shaft cracking, the characteristic natural frequency is a frequency a shaft the operating system. monitoring pinion slip, characteristic natural frequency natural frequency an including the operating system or the characteristic frequencies two coupled assemblies which includes pinion. of determining the characteristic natural frequency may include measuring vibrations of the operating system, measuring a motor of the system
 a drive shaft 14 rotatably suppoRted by bearIngs 16 wHicH arE aTtacHed tO the locomotive, A RotoR 11, a stator 19 with stator windIngs 21 aNd LEads 23. aTtAched To one enD Of DRIve ShAfT 14 is A pINiOn 18. TypIcaLly, piniOn 18 is fitted And ShRunk onto a tapEReD end 15 of drivE shAft 14. Pinion 18 engAgeS a bull GeAr 20 wHIch atTacHes to And driVEs a wheEl shaft 22 roTaTAbly suPPorted bY BEaRingS 24. The ends of wheel shAFt 22 ARe attached to reSpectiVe WHeELS 26 of The Locomotive.
alThougH ElectriC MoTOR 12 Is rESiliently suppOrted to the lOComOtive, gEaRed SYstem 10 eXperiEnCEs lArge mechaniCal vIbrations, E.g., shocK LoadingS Due to unEven poRtiOns Of raILs 30. ofTen, AfTEr sOMe PerIOd oF heavy usAgE, dRive sHaft 14 MAY CRack Due To faTigue. similarly, piniOn 18 mAy slIP reLativE to drIve sHaFt 14 witHout anY advaNcEd warning so that TorqUe is no lonGer TrAnsMiTted tO Wheels 26. sucH faIlures cAn be catAStrOpHIC, AnD repairs such as remoVaL OF eLectric mOtor 12, reFItTiNG of pinioN 18, oR rePlacEMEnt of DrivE ShAft 14, are exPensivE, LaBoR intensIvE, and reQuIre ThaT the lOComoTive be TemporarIly puLLed from service.
tHerefore, there IS a NEEd FOr an AppAratus and meThod FOr loW cosT, On-LinE MonitOring Of AN oPErating geared system In Which tHe appAratus and methOd are capabLE OF warning Of shAFt CRacking or incipIent pInion slip.
THE above-meNtionEd need is Met by the pRESent inveNtiOn wHicH reLATeS to diagnostic TEChniQuEs for moNitOring shAft CraCkiNg oR iNcipient pInion sliP iN aN oPeRatIng sySTem. In one AsPecT oF thE presENt inveNtion, A metHoD fOR moNitorinG ShAFT craCkInG or iNciPiEnt piNion SLip In an opeRating sysTem INcluDeS tHe steps Of determining A cHaracterisTiC naTural fREQuency of The operating system at a fiRSt time, dEteRminiNg thE characteRisTic natUraL FrequeNcy at a SeconD tIme, AND compARInG thE cHaracterisTIC naTural FrEqueNcy deteRmined at the first tiME to The characteriStiC natURAl FreQUeNCy dEtERmiNED at the second timE to detect a ShIFt In the charaCTerIsTic natuRal freqUency IN responSe to at leaSt one of shAfT craCKIng And incipieNt pinion Slip.
For moNItoriNG sHaft cRacKing, thE cHarActerIstic nATurAl freQuency Is A naturAl freQuEncy of a sHaft of the operating systeM. For moNitorIng Pinion sliP, thE ChaRacteristIc naTural frequEncY is A natuRal FRequeNcy oF An AssEMbly iNcluDIng a pinioN Of The OPErAting system OR THe cHaracTerIStic naTuraL frequencies of two COupled assembliEs whICH inCluDEs thE pInion.
The steps oF deTeRMIning the ChAracteristiC natural FrEQuencY may inClude mEasurinG VIbRAtions Of thE opErating sySteM, mEAsuring CuRrENt of a mOtor Of The opeRating SYsteM
 a drive shaft 14 rotatabl y supporte d bybea rin gs  16whic h are attached to t he locomotive, a rotor  11,as tato r  1 9 wit h stato r  w i n din gs  2 1 a nd le ads 2 3.Attache d to one e ndof  drive shaft 14  is a pini on18. Typicall y,pinion  1 8 i s  fitt edand s hrunko nto atapered e nd 15 ofd rive sh a f t14.Pinion 18 engages ab ull gear 20 wh ich at ta c he s toand  drives awh eel s h aft 22r ot a t a bly supported bybearings 24 .  Th e ends  o f w h eel sh aft 2 2a reattached to  res pective w heels2 6 of th e  locomo tive.Alt hou gh e l ec tr icmo t or1 2isr esi lientlysu pp orted  tot h e loco mot ive,  gear ed system 10exp erie n ces  larg e mec hani ca l vib ration s, e. g. , shock loading s du e to unev enpo rti on s ofr ails 3 0.Oft en, aft er some per io d o fheavy usage, drive  s h a ft  14 maycrackd ue  t o  fatigue .Sim ilar l y , pin ion1 8may slip  relat i ve  t o drive  s haft 1 4wit hou t any adva nced w arning s o tha t  torque is nol onger transmi t te d to whee ls26. Such fa ilur e s ca n be ca tas t rophi c, an dr ep a irs such as removal  o f elec tricmotor 12, ref itting ofp i n ion 18,or r e pl a cement of driv e sha ft 14, are expensiv e, la bor inte nsive, an d requiretha t t heloc o m ot ive be tempor a r ilypu lled fr omservice .
T her efo re,  t here is a  need fo ran  a pp ara tus a n d method  f orlo w c ost,o n-line  moni tori ng  o f  an  operat i ng g eare dsy stem  in  w hichthea ppa ratus a nd method  ar e  cap ab le  of war ning of shaft  c racking or  i nci pientp i nion sli p.
The above-mentionedn eed ismet  by t he p resent in ven tion w hic h  relat es todiagn os tic t echni q u es  fo rmonitoring s haf t cra ck ingor inci pient pinion slipi n a n operating s yst em.I n  o nea sp e ctof the p resent inventio n, a metho df or  monitorin g  sh af t crack ing orincip i ent pin ion slipin an ope ra ting s yst em include s the st eps of de t ermin i ng  a ch ara cteris ti c n atura l freq u enc y ofthe op er atingsyste mat a fir st time, determining th e char acter ist ic natura l f r equ ency at a  sec ond time,and  co mpari ngt he ch arac t er ist i c nat ural frequency de ter m i ne d at the fi r s t  ti me to  th e  chara cter istic natural fre q uency determin ed a t the  se c ondti me to detect a  sh if t in the c ha racteristic  natural  f r equen cy inrespon se to a t le a st one  ofsha ft cracki ngan d  incipi en tp inionslip .For mo nitori n g sh a f t cracking, thechara c t erist i c n atura lfrequen c y is  a natural  frequencyof a s haft  of t he oper at ing sy ste m.  For monit o ring pini on sl ip, the  c hara cte ristic  nat u r al fr eque nc y i s a natur a l  f r eq ue n cyof a n ass em blyincluding a pinion  of the ope ra tin g system or t he charact eri sticn a tural freq u enci e so f two  coupl ed ass emblies whi ch  includ est h e pinion. 
The step s  of  d eter mining t he  cha ra cte ri stic natural fr equencymay incl u d e meas uri n g vi b ration sof the opera tingsy s tem, me a s uri ng curr e ntofa m otor  of  the operating system
 a_drive shaft_14 rotatably supported by_bearings 16_which_are attached_to_the locomotive, a_rotor 11, a_stator 19 with stator_windings 21 and_leads_23. Attached to one end of drive shaft 14 is a pinion 18. Typically,_pinion_18 is_fitted_and_shrunk onto a tapered end_15 of drive shaft 14._Pinion 18_engages a bull gear 20 which attaches to_and_drives a wheel_shaft 22 rotatably supported by bearings 24. The ends_of wheel shaft 22 are attached_to respective wheels_26_of_the locomotive.
Although electric motor_12 is resiliently supported to the_locomotive, geared system 10 experiences large_mechanical vibrations, e.g., shock loadings due to_uneven portions of rails 30. Often,_after some period of heavy_usage, drive_shaft 14 may crack due_to fatigue. Similarly,_pinion 18_may slip relative_to drive shaft 14 without any_advanced warning so_that torque is no longer transmitted_to_wheels 26. Such_failures_can_be catastrophic,_and repairs such_as_removal of_electric_motor 12, refitting of pinion 18,_or_replacement of drive shaft 14, are expensive,_labor intensive, and require_that_the locomotive be temporarily_pulled from service.
Therefore, there is_a need for an apparatus and_method for_low cost,_on-line monitoring of an operating geared system in which the apparatus_and method are capable of warning_of shaft cracking or_incipient pinion_slip.
The_above-mentioned need is_met_by the_present invention which relates to diagnostic techniques_for monitoring_shaft cracking or incipient pinion slip_in an operating system._In_one aspect of the present invention,_a method for monitoring shaft cracking_or incipient pinion slip in_an_operating_system includes the steps of_determining a characteristic natural frequency of_the operating system_at a first time, determining the characteristic_natural_frequency at a second time, and_comparing_the characteristic natural frequency determined at_the_first_time to the characteristic natural_frequency determined at the second time_to detect a shift in the characteristic natural frequency_in response to_at least one of shaft_cracking_and_incipient pinion slip.
For monitoring shaft cracking, the characteristic natural frequency_is a_natural frequency of_a shaft of the operating system. For monitoring pinion slip,_the characteristic natural frequency is a natural_frequency of an assembly including a pinion of the operating system_or the characteristic natural frequencies of two coupled_assemblies which includes the pinion.
The steps of_determining the characteristic natural_frequency_may include measuring vibrations of the operating_system,_measuring_current_of a motor_of the operating_system