SECTION 7 - AHR International

ENGINEERINGBearing Installation and RetentionTHREADED RETAINER RETENTIONSTAKING PROCEDUREThreaded bearing retainers, as shown in 42 , offer an excellentbearing retention method due to ease of bearing replacement,high axial thrust load capabilities, and ease of assembly inareas where accessibility to conventional staking would bedifficult.1. Install bearing into housing per 40 and position it symmetrical about housing centerline within .005.2. Mount bearing and top anvil over bottom anvil guide pin asshown in 45 .3. A trial assembly should be made for each new bearing lotto determine the staking force necessary to meet the axialretention load required. Excessive force should be avoidedsince this may result in bearing distortion and seriouslyimpair bearing function and life. (See table 8 for recommended Staking Force, page 75).BOLTED PLATE RETENTIONFor high retention capability and ease of bearing replacement,the bolted plate method, as shown in 43 , is recommended.However, space requirements and weight will increase.HOUSING STAKE RETENTION4. Apply the staking force established by trial assembly, rotateassembly 90 and re-apply force.Housing stake retention, as shown in 44 , has many shortcomings when compared to V-groove staking. The major consideration is race contraction, which adversely affects internalfit-up. Housing stake retention should be used only whenthere is insufficient space on the race face for a V-groove orthe race material is not ductile. When mounting, the bearingand its housing are supported by an anvil while the stakingtool is forced into one side of the housing near the edge of thebearing. This action displaces a small amount of the housingmaterial over the race chamfer. The opposite side of thehousing is then staked in the same manner.5. After staking, a slight gap may exist between race lip andhousing chamfer as shown in detail in 45 . This gap shouldnot be a cause for rejection providing the bearing meetsthe thrust load specified.42V-GROOVE RETENTIONV-groove retention, as shown in 45 , is the most widely usedand recommended. The bearing outer race has a small groovemachined into each face, which leaves a lip on the race O.D.corners. With the use of staking tools, these lips are swaged(flared) over the chamfered edges of the housing.43STAKING TOOL90 45 .022 REF.The prerequisites for good V-groove staking are proper sizehousing chamfers, staking tools that match the V-groove size,and the availability of a hydraulic or pneumatic press capableof applying the staking force. To use V-groove stakingsuccessfully, the following conditions must be met:STAKINGANVIL44Housing Stake RetentionSTAKINGTOOL1. Race hardness: Rc40 max.2. Sufficient space on the race face for machining a groove.For V-groove sizes, see 46 .3. V-groove size capable of carrying the axial load, seeThreadedRetainer VIL4574V-Groove Staking MethodBolted PlateRetention

PS30 STAKING FORCE60 The staking force equals the product of the bearing O.D. anda constant for each groove size (see table 8). For example, abearing with a “B” size V-groove and 1.500 O.D., the stakingforce will be 1.500 X 12,000 lbs. 18,000 lbs.TX.020R (GROOVES B,C & D).010.015R (GROOVE A ONLY).005These staking forces are valid for outer race materials havingan ultimate tensile strength of 140,000 psi.46Staking forces for other materials are proportional to theultimate tensile strength or the materials as compared to140,000 psi.V-Groove SizesV-Groove SizesGrooveSizeThese staking forces should be used as a general guide toestablish a starting point. Lower forces may be adequate orhigher forces may be necessary depending on staking technique and axial load requirements.As a rule, only the amount of force required to get the desiredamount of retention should be used.P .000-.015S .000-.010X .060.030.080.156D.080.045.105.188*For TEFLON lined bearings, add single liner thickness to “T Min.”The use of proper fits and staking techniques should not causesignificant changes in bearing preload.TABLE 8: Staking ForceAs a minimum, the first and last article staked should beproof-tested. 48 shows a method for proof-testing stakedbearings for axial retention. This is the generally acceptedmethod for checking retention used by bearing and air framemanufacturers.Groove Size*Lbs.A7700B12000C17700D25800*See 46 for groove sizes.shows allowable design thrust loads for bearing O.D.’s Theloads shown should be obtainable using staking tools with 45 outside angles.LOAD474847Staked BearingProof TestingMethodThrust Loads Based on 46 GrooveTypes and Materials Specified.12,000TYPE C – STL & CRES, R/C 30-36LOAD11,000THRUST LOADS MAXIMUM LBS.(DESIGN REFERENCE)10,000TYPE C – STL & CRES, R/C 26-329,000TYPE A & B – STL & CRES, R/C 30/368,000TYPE A & B – STL & CRES, R/C 26/327,0006,000TYPE C – 303 CRES & AL BR5,000TYPE C – ALUMINUMTYPE A & B – 303 CRES & AL BRTYPE A & B – RACE O.D. IN INCHES2.02.252.5TEFLON is a Du Pont registered trademark75

ENGINEERINGBearing Installation and Retentionfinal layout drawing should be made to check fit-up. NHBBmanufactures staking tools to meet many customers’ needs.To obtain staking tools specially manufactured by NHBB,please refer to ordering information on page 77.V-GROOVE STAKING TOOLThe staking tool and staking anvil depicted in 49 and 50 aremade from tough, hardenable tool steel (for example, A-2) andheat treated to Rc55 to 60. The critical dimension of the toolsare as listed. As a final check on the staking tool and anvil, a.001D.001D.010.005 R CONTINUOUS8-D-B25 21 (A) PIN DIAMETER0/ .001 D0/ .001 DC49Staking tool designA Ball bore min. - .001(Tolerance .000/ - .001)B Bearing O.D. - 2 X Min. lip thickness - Min. groove width(Tolerance .005/ - .000. See 46 for lip thickness (page 75)“S” and groove width “X”.)C Adequate stakes for most applications are obtained with staking tools having45 to 50 outside angles. When required, secondary staking tools having anoutside angle of 60 to 70 can be used to obtain maximum retention and toreduce the amount of gap between the housing chamfer and the lip of the outer race.001ED0/ .005 ECBA0/ .001 E-E-50A .001Staking Anvil DesignEBall bore min. - .001(Tolerance .000/ - .001)B Ball.spherical dia. - Race width .03022(Tolerance .010)C Body.head dia. - Body width22(Tolerance .010)D Ball width max. - Race width min. .0152(Tolerance .010)76

Staking Tool Sets – Ordering InformationHydraulic (Anvil) staking tools are available for all NHBB standard and special spherical bearings with staking grooves. Eachset consists of one staking (flaring) tool and one staking anvil,both with guide pins installed. For spherical bearings in thiscatalog, order staking tool sets by the part numbers below.NHBBPart NumberBoreFor special (non-catalog) bearings or larger sizes, consult NHBB.Staking ToolPart NumberEXAMPLES:NHBB P/NSTAKING TOOLADB( )V3STN 00031. ADB10VSTN 0010ADB( )V(L)4STN 00042. ABG8V (L)STN 0008HT( )V(L1)5STN 00053. ADW5VSTW 0005AG( )V6STN 00064. ADBY6VSTY 0006AG( )V3007STN 0007HSBG( )V8STN 0008AHT( )V9STN 000910STN 0010ABG( )V(L)12STN 0012ABG( )V-501(L)14STN 0014ADW( )V3STW 0003AW( )V4STW 0004ADW( )V(L)5STW 0005WHT( )V(L1)6STW 0006ADWL( )V7STW 0007ADWL( )V(L)8STW 0008WHTL( )V(L1)9STW 000910STW 001012STW 001214STW 001416STW 00163STY 0003AHET( )VADBL( )VHTL( )V(L1)ADBY( )VASBY( )V4STY 0004ADBY( )V(L)5STY 00056STY 00067STY 00078STY 00089STY 000910STY 001012STY 001214STY 001416STY 001620STY 002024STY 002477

ENGINEERINGLoad Ratings and Misalignment Capabilities51CDEFINITIONS FOR ROD END ANDSPHERICAL BEARING TERMINOLOGYMISALIGNMENTRadial LoadA load applied normal to the bearing bore axis (seeAxial LoadA load applied along the bearing bore axis (see51A ).ANGLE OFMISALIGNMENTAXIALRADIAL51B ).51A51BStatic LoadThe load to be supported while the bearing is stationary.Dynamic LoadThe load to be supported while the bearing is moving52 .Static Radial Limit LoadThat static load required to produce a specified permanent setin the bearing. It will vary for a given size as a function of configuration. It may also be pin limited, or may be limited as afunction of body restraints as in the case of a rod end bearing.Structurally, it is the maximum load which the bearing can seeonce in its application without impairing its performance.RADIALStatic Radial Ultimate LoadThat load which can be applied to a bearing without fracturingthe ball, race or rod end eye. The ultimate load rating is usually,but not always, 1.5 times the limit load. Plastic deformationmay occur.52Static Axial Limit LoadThat load which can be applied to a bearing to produce aspecified permanent set in the bearing structure. Structurally,it is the maximum load which the bearing can see once in itsapplication without impairing its performance.53Static Axial Ultimate LoadThat load which can be applied to a bearing without separatingthe ball from the race. The ultimate load rating is usually, butnot always, 1.5 times the limit load.Axial Proof LoadThat axial load which can be applied to a mounted sphericalbearing without impairing the integrity of the bearing mountingor bearing performance. It is always less than the static axiallimit load. Bearing movement after proof load is usually .003or less. See the Bearing Installation and Retention section forfurther information beginning on page 75.TENSIONLOAD78OSCILLATIONCOMPRESSIONLOAD

RotationIs the relative angular displacement between the ball and racethat occurs within the plane perpendicular to the axis of the ballbore (see 53 ). The direction of rotation is about the axis of theball bore.GAGELOADHOUSINGBEARINGPIN0.000 - 0.001LOOSE FITMisalignmentIs the relative angular displacement between the ball and racethat occurs within any plane that coincides with the axis of theball bore (see 51C ). The direction of misalignment is about anyaxis perpendicular to the ball bore.Oscillating Radial Load or Dynamic LoadThe uni-directional load produces a specified maximumamount of wear when the bearing is oscillated at a specifiedfrequency and amplitude. This rating is usually applied to selflubricating bearings only. The dynamic capability of metal-tometal bearings depends upon the degree and frequency ofgrease lubrication, and that of dry film lubricated bearings uponthe characteristics of the specific dry film lubricant applied.54Radial Test FixtureDIALINDICATORDIAL INDICATOR5.5 LBS.GAGE LOADRadial PlayRadial play (or radial clearance) is the total movement betweenthe ball and the race in both radial directions less shaft clearance (when applicable). Industry specifications have established the gaging load at 5.5 lbs., and this is now consideredas the industry standard (see 54 and 55 ). Unless otherwisespecified, the industry wide standard for metal-to-metal spherical bearing and rod end radial clearance is “free-running to.002 max.” Radial play is sometimes referred to as “Diametralclearance.” The two terms are synonymous.SUPPORT55Method of MeasuringRadial PlaySPHERICAL BEARING5.5 LBS.GAGE LOADAxial PlayAxial play (or axial clearance) is the total movement betweenthe ball and the race in both axial directions (see 56 ). Thegaging load is again 5.5 lbs. Axial play is a resultant, beinga function of radial play, of ball diameter and race width. Theratio between radial and axial play varies with bearinggeometry.GAGELOADHOUSINGFatigue Load of Rod EndsAerospace Standard series rod end bearings AS81935 must becapable of withstanding a minimum of 50,000 cycles of loadingwhen tested as follows: The loading must be tension-tensionwith the maximum load equal to the fatigue loads listed on theNHBB drawing of the ADNE and ADN series rod end bearings.The minimum load must be equal to 10% of the fatigue loads.BEARINGDIALINDICATOR5679Axial Test Fixture

ENGINEERINGLoad Ratings and Misalignment CapabilitiesLOAD RATINGSSPHERICAL BEARING LOAD RATINGSThe load rating of a bearing is determined by the dimensionsand strength of its weakest component. External factors, suchas mounting components, pins, bolts, and housings are notconsidered part of a bearing when load ratings are investigatedbut should be considered separately.The weakest part, or load-limiting area, of a spherical bearingis its race. For this reason, formulas have been developed thatuse the race to calculate static load ratings based on size andmaterial strength. The static load rating formulas for self-lubricating and metal-to-metal spherical bearings are shown in 57and 58 . These formulas will yield approximate ratings, whichshould be used as ballpark numbers for bearing design.The allowable radial stress values given in the tables weredetermined from the ultimate tensile strength specificationsfor various race materials. Allowable axial stress values werederived from material yield strengths.Allowable Stress - TEFLON -Lined BearingsAllowable Stress - Metal-to-Metal BearingsT AVG.T AVG.AXIALAXIALd RADIALd RADIALLoad Projected Area x Allowable StressDB57Load Projected Area x Allowable StressRadial Projected Area (.83T .92G)(DB)Radial Projected Area (.91T) (DB)Axial Projected Area .636T2 .05DBAxial Projected Area .636T2DBGStatic Load Rating Formulas forSelf-Lubricating Spherical Bearings58Static Load Rating Formulas forMetal-to-Metal Spherical BearingsAllowable Stress TEFLON Lined Bearings (psi)Standard Groove SizesRaceMaterialBearing SizeBore 4PH, Rc28 MIN1125007500067500450003&4ALUM 2024-T35160000400003600024000.0625 - 10.07812 - 16.09420 & above.109Allowable Stress Metal-to-Metal Bearings (psi)RaceMaterialRadialUltimateLimit17-4PH, Rc32-361500001000001250004130 Rc32-3615000010000012500083000A286 (AMS O 15 BronzeAMPCO is a registered trademark of AMPCO Metal Inc.TEFLON is a Du Pont registered trademark80AxialUltimateLimit83000

ROD END BEARING LOAD RATINGD MIN.Rod end bearing load ratings can be generated only after carefully determining the load restrictions that each element of therod end bearing imposes on the entire unit. In order to generatea frame of reference, consider the rod end bearing as a clockface, with the shank pointing down to the 6 o’clock position.The limiting factors in rating a rod end bearing are as follows:T MIN.BAXIALd1. The double shear capability of the bolt passing throughthe ball bore.NORMALFAILUREZONE2. The bearing capability, a function of race material or selflubricating liner system.3. The rod end eye or hoop tension stress in the 3 o’clock-9o’clock position.RADIALJ MIN.594. The shank stress area, as a function of male or female rodend configuration.MALE5. The stress in the transition area between the threadedshank transition diameter and the rod end eye or hoop.FEMALEThe shank stress area (SSA) is a function of being either maleor female, as follows:For the male:πSSA (minor thread diameter)2 4Most rod ends will fail under tension loading in about the 4o’clock-8 o’clock portion of the eye or hoop. The Net TensionArea (NTA) can be found as follows:For the female:πSSA [J2 – (major thread diameter)2] 42– T2 – BxTNTA .008726 x D2 x Sin-1 T T D D 2( )Pin shear stress (PSS) for load "F" is as follows:2FPSS πd2Solve the Sin-1 T in units of degrees, not radians.D( )This simple rod end load rating formula does not take into consideration such variables as special body shapes, thin racesections, hardness variation, lubrication holes, grooves, andhoop tension, which could significantly affect the load rating.Contact NHBB Applications Engineering for assistance indetermining the load rating for specially designed Rod Endsand Sphericals.The axial load capability of a rod end is a function ofthe following:1. The retention method used to mount the bearing in the rodend eye. See the Bearing Installation and Retention sectionfor further information beginning on page 71.2. The axial load capability of the bearing element.3. The bending moment, if any, placed on the rod end.81

ENGINEERINGLoad Ratings and Misalignment CapabilitiesNHBB TESTING CAPABILITIESPV FactorWhile not a type of loading, the PV factor is very useful in comparing and predicting test results on high speed-low load applications such as helicopter conditions.Mechanical Test EquipmentNHBB has a variety of equipment to test spherical and rod endbearings under diverse conditions. NHBB performance dataexceeds military and individual manufacturers’ design requirements. Maximum capabilities of NHBB testing machines areshown in table 9.PV is the product of the stress (psi) and the velocity (fpm)applied to a bearing. Caution must be advised when considering extreme values of psi and fpm. The extreme must be considered individually, as well as together.Polymer Test EquipmentNHBB has the following thermal analysis (TA) equipment tosupport and control the quality of composites/polymersthrough analytical techniques that measure the physical andmechanical properties as a function of temperature and time:Because the PV factor is derived from the geometry andoperating conditions of a bearing, it serves as a commondenominator in comparing or predicting test results. For thisreason PV values are included in the wear curves of 22 and23 (page 61) in the Self-Lubricating TEFLON Liner Systemssection, page 60.1. Differential Scanning Calorimeter (DSC)2. Thermogravimetric Analyzer (TGA)3. Dynamic Mechanical Analyzer (DMA)The formula for determining the PV value for a sphericalbearing is as follows:PV ( ) (cpm) (DB) (psi) (.00073)4. Thermomechanical Analyzer (TMA)5. Thermo-Oxidative Stability Test (TOS)6. Acid Digestion SystemWhere: total angular travel in degrees per cycle(ie. - 25 100 total travel)7. Fourier Transform Infrared Spectroscopy (FTIR)cpm cycles per minute (oscillation rate)DB ball diameterpsi bearing stressTABLE 9: NHBB Testing CapabilitiesForceDynamic Oscillating Radial LoadThe dynamic oscillating radial load ratings given in this catalogfor ADB, ADW, ADBY, ADB-N, ADW-N, ADBL and ADWL seriesself-lubricating spherical bearings are based on testing inaccordance with AS81820. For conditions other than thosespecified by AS81820 contact NHBB Applications Engineering.Material Testing (Universal Testing Machine)110,000 Lbs.Static Compression/Tension200,000 Lbs.Low Speed Oscillation (up to 50 cpm)Uni-directional Loading(1 machine, 2 station) (700 F)20,000 Lbs.(1 machine, 2 station) (700 F)70,000 Lbs.Moderate To High Speed OscillationUni-directional Load (room temp.)(1 machine, 2 station) (1000 cpm)1,000 Lbs.(1 machine, 2 station) (1500 cpm)1,000 Lbs.(1 machine, 6 station) (200-600 cpm)8,000 Lbs.Low Speed OscillationReversing or Alternating Load (room temp.)(1 machine, 2 station) (up to 50 cpm)40,000 Lbs.High Speed, OscillationReversing and Alternating Load (room temp.)(2 machines, 1 station each) (400 cpm)2,500 Lbs.Airframe Track RollerTesting Machine (roller against flat plate)8260,000 Lbs.

FORMULA FOR DETERMINING MISALIGNMENT OF ROD END & SPHERICAL BEARINGSAAAA60WTA SIN– SIN-1EE-160 Standard Method61BTA COS-1 – SIN-1EE6261 Design ReferenceA COS-1ST– SIN-1EEMost standard rod end andThis method may be used as62 High MisalignmentSeries Methodspherical bearing misalignmentdesign reference for installation(Neck balls only)angles specified in NHBB cata-purposes, but should not belogs are based on this method.used as a functioning misalign-63A SIN-1WT– SIN-1DD63 Rod End ClevisMisalignmentment under load.HOW NHBB SPECIFIES CATALOG BEARING AND ROD END MISALIGNMENTThe misalignment angle of a rod end or spherical bearing refersto the angle between the ball centerline and the outer membercenterline when the ball is misaligned to the extreme positionallowed by the clevis or shaft design, as applicable.more typical than that of 63 . As pictured in 65 , the clevis slot iswider than the ball to permit installation of flanged bushingsand/or spacers. This results in a higher but more variable misalignment capability, and the angle of misalignment becomesa function of the user’s bushing flange or spacer diameterinstead of the fixed rod end head diameter.NOTE: Since angle “A” applies equally on both sides of the centerline, it follows that total misalignment of the bearing is double the value obtained for “A”.through 63 illustrate varying types of bearing misalignmentand a formula for calculating eachWhere:60A angle of misalignmentD head diameter (rod end)S shoulder diameter (neck ball)W width of ballB bore of ballE ball s

STAKING TOOL 45 90 .022 REF. STAKING ANVIL STAKING TOOL GUIDE PIN BEARING HOUSING STAKING ANVIL 5 DETAIL. 43 44 45. Bolted Plate Retention Housing Stake Retention V-Groove Staking Method Threaded Retainer Retention. 42. THREADED RETAINER RETENTION. Threaded bearing retainers, as shown in