Fluid Film Thrust Bearings: Fundamentals, Damage ...

1 February 20051(c) 2006, Pioneer Motor bearing CompanyFluid film Thrust Bearings: Fluid film Thrust Bearings: fundamentals , Damage fundamentals , Damage evaluation , & RepairEvaluation, & RepairPioneer Motor BearingPioneer Motor BearingMay 2006 May 2006 VIBRATION INSTITUTE MEETINGVIBRATION INSTITUTE MEETINGCHARLOTTE, NCCHARLOTTE, NC(c) 2006, Pioneer Motor bearing CompanySlide Slide 22 OutlineOutlinennBasic Design CriteriaBasic Design CriteriannThrust bearing MonitoringThrust bearing MonitoringnnDamage investigationDamage investigationnnDamage mechanismsDamage mechanismsnnInspectionInspectionnnRepair Repair(c) 2006, Pioneer Motor bearing CompanySlide Slide 33 HistoryHistorynnWithout question Without question the most the most significant significant mechanical mechanical invention in the invention in the world was:world was:The The WheelWheel(c) 2006, Pioneer Motor bearing CompanySlide Slide 44 HistoryHistorynnHowever, almost However, almost immediately upon immediately upon discovery of the discovery of the wheel, the need wheel, the need for bearings was for bearings was also discovered:also discovered:(c) 2006, Pioneer Motor bearing CompanySlide Slide 55 HistoryHistorynnWhich has Which has led to one led to one of the most of the most elusive elusive searches in searches in human human historyhistory(c) 2006, Pioneer Motor bearing CompanySlide Slide 66 HistoryHistorynnAs one can As one can observe from this observe from this wooden wheel wooden wheel dating to 2700 dating to 2700 BC, axels where BC, axels where used to allow used to allow support by radial support by radial and Thrust and Thrust Bearings: bearings.

2 February 20052(c) 2006, Pioneer Motor bearing CompanySlide Slide 77 Load Orientations: Load Orientations: radial/thrustradial/thrustSlide Slide 88 Thrust BearingThrust BearingnnSupport axial load from the processSupport axial load from the Water or steam Water or steam pressurennThrust runner surfaceThrust runner surfacennGenerally flat Generally flat (<13 (<13 m = = ))nn16 16 in RMSin RMSnnThrust bearingThrust bearingnnGenerally circumferential segmentsGenerally circumferential segmentsnnTend to be Tend to be squaresquare --length=widthlength=widthnnTradeTrade-- offoffnnLarger loaded area gives more friction lossLarger loaded area gives more friction loss(c) 2006, Pioneer Motor bearing CompanySlide Slide 99 Thrust ClearanceThrust ClearancennTypical operating clearanceTypical operating clearanceHuman hair aboutHuman hair about75 75 m ( ( ) diameter)

3 DiameterTypical operating clearance Typical operating clearance about 25 about 25 m ( ( ).).RUNNERRUNNERBEARINGBEARINGRef: ROTECHRef: ROTECH(c) 2006, Pioneer Motor bearing CompanySlide Slide 1010 Thrust LoadThrust LoadnnLoad capacity based onLoad capacity based onnnHydrodynamic pressure profileHydrodynamic pressure profilennPad areaPad areannNominallyNominallynnReduced by grooving Reduced by grooving ()22** = (c) 2006, Pioneer Motor bearing CompanySlide Slide 1111 Thrust bearing DesignsThrust bearing DesignsnnFlat WasherFlat WashernnFlat Flat BabbittedBabbittedFace With GroovesFace With GroovesnnTaperTaper--Land Land BabbittedBabbittedFaceFacennTilting Pad Thrust BearingTilting Pad Thrust BearingnnEqualized Tilting Pad Thrust Equalized Tilting Pad Thrust BearingBearing(c) 2006, Pioneer Motor bearing CompanySlide Slide 1212 Flat WashersFlat WashersnnSimple but useful Simple but useful only with minimal only with minimal speed and load speed and load conditionsconditionsnnGrease lubricated Grease lubricated February 20053(c) 2006, Pioneer Motor bearing CompanySlide Slide 1313 BumperBumper ThrustThrustBabbittedBabbittedaxial surfaces to resist motion of shaft surfaces to resist motion of shaft may have radial pockets or may have radial pockets or grooving.

4 (c) 2006, Pioneer Motor bearing CompanySlide Slide 1414 Flat Flat BabbittedBabbittedThrust Face Thrust Face with Grooveswith GroovesnnUseful as a bumper, Useful as a bumper, or locating bearingor locating bearingnnOil or grease Oil or grease lubricatedlubricatednnNo theoretical load No theoretical load capacitycapacitynnPractical capacity Practical capacity around 50 to 75 PSIaround 50 to 75 PSI(c) 2006, Pioneer Motor bearing CompanySlide Slide 1515 BumperBumper ThrustThrustRadial Radial grooves grooves enhance load enhance load (c) 2006, Pioneer Motor bearing CompanySlide Slide 1616 TaperTaper--Land Thrust BearingLand Thrust BearingnnOptimized for only Optimized for only one speed and load one speed and load combinationcombinationnnTaper for oil wedge Taper for oil wedge formation is formation is machined into the machined into the bearing surfacebearing surfacennAlignment is critical Alignment is critical to operationto operationnnPractical load limit Practical load limit 150 to 225 PSI150 to 225 PSI(c) 2006, Pioneer Motor bearing CompanySlide Slide 1717 Simple TaperedSimple Tapered--Land ThrustLand Thrust (c) 2006, Pioneer Motor bearing CompanySlide Slide 1818 Compound TaperedCompound Tapered--Land ThrustLand ThrustTaper is steeper Taper is steeper at the inner at the inner diameter than diameter than at the outer at the outer diameter.

5 Diameter. Taper is Taper is generally generally .. Land region is Land region is 20054(c) 2006, Pioneer Motor bearing CompanySlide Slide 1919 FluidFluid-- film Thrust Bearingfilm Thrust BearingnnAnnulus controls axial controls axial load capacityMaximum load capacityTiltingTilting--padpadbearingbea ring(c) 2006, Pioneer Motor bearing CompanySlide Slide 2020 Tilting Pad Thrust BearingTilting Pad Thrust BearingnnSelf Optimizing based Self Optimizing based on applied load and on applied load and speedspeednnMaximum Flexibility Maximum Flexibility re: potential re: potential modificationsmodificationsnnAlignment is criticalAlignment is criticalnnLoad Capacity in Load Capacity in excess of 600 PSIexcess of 600 PSI(c) 2006, Pioneer Motor bearing CompanySlide Slide 2121 Tilting Pad Thrust BearingsTilting Pad Thrust BearingsEqualizing linkages correct for housing linkages correct for housing linkages do not correct for rotating collar linkages do not correct for rotating collar : Kingsbury literatureRef: Kingsbury literature(c) 2006, Pioneer Motor bearing CompanySlide Slide 2222 NonNon--Equalizing SupportEqualizing SupportRef: Constantinescu, p.

6 : Constantinescu, p. 354.(c) 2006, Pioneer Motor bearing CompanySlide Slide 2323 NonNon--Equalized BearingEqualized bearing (c) 2006, Pioneer Motor bearing CompanySlide Slide 2424 Self Equalizing Tilting Pad Self Equalizing Tilting Pad Thrust BearingsThrust BearingsnnMaximum capacity in Maximum capacity in given spacegiven spacennSelf optimizing oil Self optimizing oil filmfilmnnCan accommodate Can accommodate collar to housing collar to housing misalignmentmisalignmentnnNot designed for Not designed for dynamic dynamic misalignmentmisalignmentnnLoad Capacity in Load Capacity in excess of 600 PSIexcess of 600 PSIF ebruary 20055(c) 2006, Pioneer Motor bearing CompanySlide Slide 2525 Equalizing LinkagesEqualizing LinkagesRef: Constantinescu, p. : Constantinescu, p. is to Intent is to equally load equally load each of the each of the Thrust pads in Thrust pads in spite of spite of variations in variations in pad thickness or pad thickness or misalignment of misalignment of the housing to the housing to the runner.

7 (c) 2006, Pioneer Motor bearing CompanySlide Slide 2626 AntiAnti--Rotation PinsRotation PinsProvides:Provides:Locates shell in housingLocates shell in housing CircumferentialCircumferentialPrevent rotation of the cage Prevent rotation of the cage in the the housing.(c) 2006, Pioneer Motor bearing CompanySlide Slide 2727 Combined Journal ThrustCombined Journal ThrustLobed journal Lobed journal bearingbearingTapered Thrust Tapered Thrust bearingbearing(c) 2006, Pioneer Motor bearing CompanySlide Slide 2828 Oil Distribution GeometryOil Distribution GeometryOIL INLET OIL INLET HOLEHOLER adial grooveRadial grooveAxial grooveAxial grooveBleederBleederBleedersBleedersSpre ader GrooveSpreader Groove(c) 2006, Pioneer Motor bearing CompanySlide Slide 2929 Thrust bearing FlowsThrust bearing FlowsRef. Kingsbury Ref. Kingsbury sales literature, sales literature, (c) 2006, Pioneer Motor bearing CompanySlide Slide 3030 Tilting Pad Thrust BearingsTilting Pad Thrust BearingsRef: Kingsbury literatureRef: Kingsbury literatureFebruary 20056(c) 2006, Pioneer Motor bearing CompanySlide Slide 3131So, how much load can So, how much load can mymybearing take?

8 bearing take?nnThis depends This depends on where you on where you are operating are operating within the within the regime of the regime of the bearing bearing performance performance parametersparametersnnNo, I am not a No, I am not a lawyerlawyer(c) 2006, Pioneer Motor bearing CompanySlide Slide 3232 What can be done to What can be done to increase load capacity?increase load capacity?nnFirst, understand the shortcomings First, understand the shortcomings of the existing bearingof the existing bearingnnSecond, consider modifications to Second, consider modifications to the operating parametersthe operating parametersnnThird, consider an upgrade to the Third, consider an upgrade to the basic bearing designbasic bearing design(c) 2006, Pioneer Motor bearing CompanySlide Slide 3333 Deal with low speed wearDeal with low speed wearnnHydrostatic lift system to provide Hydrostatic lift system to provide hydrostatic oil films where hydrodynamic hydrostatic oil films where hydrodynamic oil films may not otherwise be presentoil films may not otherwise be presentnnStart up operationStart up operationnnTurning gear operationTurning gear operationnnSome emergency conditionsSome emergency conditionsnnPer DIN 31652 part 3 consider hydrostatic lift Per DIN 31652 part 3 consider hydrostatic lift where startup loads exceed startup loads exceed MPaMPa(363(363--435 435 psipsi))nnMay be required for lower loadsMay be required for lower loads(c)

9 2006, Pioneer Motor bearing CompanySlide Slide 3434 Hydrostatic Lift SystemsHydrostatic Lift SystemsnnInject high pressure oil (typically > Inject high pressure oil (typically > 1000 1000 psipsi) at the location of the ) at the location of the highest loadinghighest loadingnnHydrostatic film is developed Hydrostatic film is developed through pressure, film thickness is through pressure, film thickness is controlled by flowcontrolled by flownnQuite often, many bearings are fed Quite often, many bearings are fed by a common high pressure headerby a common high pressure header(c) 2006, Pioneer Motor bearing CompanySlide Slide 3535 Hydrostatic Lift SystemHydrostatic Lift SystemnnIntroduce externallyIntroduce externally--pressurized oil pressurized oil into bearing cavity for operation at into bearing cavity for operation at low surface speeds and high loadslow surface speeds and high loadsnnForms hydrostatic bearing on lower halfForms hydrostatic bearing on lower half(c) 2006, Pioneer Motor bearing CompanySlide Slide 3636 Hydrostatic Lift SystemHydrostatic Lift SystemHydrostatic lift in tilting pad Thrust lift in tilting pad Thrust 20057(c)

10 2006, Pioneer Motor bearing CompanySlide Slide 3737 Main oil pump is shaft drivenMain oil pump is shaft drivenAC & DC pumpsAC & DC pumpsSample Hydrostatic Lift Oil SystemSample Hydrostatic Lift Oil SystemSchematic of Schematic of TurbineTurbine--Generator Generator Hydrostatic Hydrostatic Lift SystemLift SystemEach radial bearing #3 Each radial bearing #3--8 has a 8 has a separate pressurized hydrostaticseparate pressurized hydrostatic--lift supply (1500 psig), separate lift supply (1500 psig), separate supply pump with a gravity (or supply pump with a gravity (or slight vacuum) drain back to the slight vacuum) drain back to the (c) 2006, Pioneer Motor bearing CompanySlide Slide 3838OK smart guy, IOK smart guy, I ve already got ve already got a tilting pad Thrust bearing , a tilting pad Thrust bearing , Now what?Now what?nnConsider upgrading specific design Consider upgrading specific design features of the assemblyfeatures of the assemblynnDirected lubricationDirected lubricationnnAlternative materialsAlternative materialsnnOffset pivotsOffset pivots(c) 2006, Pioneer Motor bearing CompanySlide Slide 3939 Effect of Pivot OffsetEffect of Pivot Offset(c) 2006, Pioneer Motor bearing CompanySlide Slide 4040 Effect of ChromeEffect of Chrome--Copper Alloy Copper Alloy Backing MaterialBacking Material(c) 2006, Pioneer Motor bearing CompanySlide Slide 4141 Thrust bearing MonitoringThrust bearing MonitoringnnTemperatureTemperaturennLoad LoadnnThrust Collar PositionThrust Collar Positio