Hub Unit Bearings - NSK

1 Comfort for the 21st CenturyIntelligently and reliably meeting the needs of a widerange of vehicle unit Bearings1 Hub unit BearingsCONTENTS1. Types and Features of Hub unit Bearings1-1. Categories of hub unit Bearings 31-2. HUB I 51-3. HUB II 71-4. HUB III 92. Selection of Hub unit Bearings2-1. Overview of selection 112-2. Selection of bearing types 142-3. Types and characteristics of Bearings 153.

2 Selection of Dimensions of Hub unit Bearings3-1. Service life calculation 163-2. Rigidity 183-3. Strength 194. Fit and Preload of Hub unit Bearings4-1. Fit and preload 214-2. Recommended fitting measurements 214-3. Fitting tests 215. Hub unit bearing Seals 226. Hub unit bearing Grease 247. Material for Hub unit Bearings7-1.

3 Material for raceway rings and rolling elements 257-2. Cage material 268. Hub unit Bearings with Integral ABS Sensors8-1. Multi-pole magnetic encoders for ABS 268-2. Hub unit Bearings with integral ABS sensors 279. Hub unit Bearings with Swaging 2810. Recommended bearing Nomenclatures 29 HUB IBWD type 31 KWD type 33 HUB IIBWK outer ring rotation type (for non-driven wheels) 35 BWK inner ring rotation type(for non-driven wheels) 36 BWK inner ring rotation type(for driven wheels) 37 KWH inner ring rotation type(for driven/non-driven wheels) 37 HUB IIIBWKH inner ring rotation type(for non-driven wheels) 39(for driven wheels)

4 40 Appendix Table 41 Hub unit bearing Dimension Table21. Types and Features of Hub unit Bearings1-1. Categories of hub unit bearingsHub unit Bearings for automobile wheels are comprised of bearing rings, rolling elements, and cages, similar to general-purpose rollingbearings. The first-generation hub unit (Hub I), second-generation hub unit (Hub II), and third-generation hub unit (Hub III) varyaccording to the integration of the Bearings and their peripheral components. In addition, the forms are categorized by usage condition(rotations of outer rings or inner rings) and component location (for driven wheels or non-driven wheels).

5 Hub UnitBearingsTapered rollerbearingsBall bearingsHUB IOuter ring rotationFor driven and non-driven wheelsFor non-driven wheelsHub unit Bearings43 HUB IIHUB IHUB IIHUB IIII nner ring rotationOuter ring rotationInner ring rotationFor driven and non-driven wheelsFor non-driven wheelsFor driven wheelsOuter ring rotationInner ring rotationFor non-driven wheelsFor non-driven wheelsFor driven and non-driven wheelsFor non-driven wheelsFor driven wheelsHUB IInner ringTapered rollerOuter ringCageSealBWD (Ball Bearings ) for driven and non-driven wheelsKWD (Tapered roller Bearings ) for driven and non-driven wheelsFor HUB I, NSK uses proprietary bearing -type designationssuch as BWD for ball Bearings and KWD for tapered rollerbearings. The HUB I units are double-row angular contactball Bearings (BWD) and double-row tapered roller Bearings (KWD) with back-to-back duplex outer preload adjustments (including dimensional adjustmentsby shims) are required on the assembly line.

6 The initial axialclearance is properly pre-set for the preload to fall within thespecified range after mounting. In addition, the integral sealeliminates the need for automotive makers to externally apply seals. NSK uses bearing reference for hub unit Bearings clarifying boundary dimensions, types, and specification codes. Below areexamples of bearing reference:Serial I (Ball Bearings )Example: BWD3518 Bore diameter 35 mmSerial codeMaterial codeHUB I (Tapered roller Bearings )Example: KWD3804Ag3 Bore diameter 38 mmHub unit Bearings1-2. HUB I65 Outer ringInner ringBallCageSealHUB IIFlanged outer ringSealBallInner ringCageHub boltFlanged outer ringInner ringHub boltSealTapered rollCageBWK (Ball Bearings )KWH (Tapered roller Bearings )Flanged outer ringSealInner ringSeal Tapered rollerCageFor HUB II, NSK uses proprietary bearing -type designationssuch as BWK for ball Bearings and KWH for tapered rollerbearings.

7 HUB II configurations are BWD or KWD HUB I withflanged outer rings. Outer ring rotation type (for non-driven wheels):Wheels and brake disks are mounted at the flanges. Spindlesare inserted into the inner rings and fixed with nuts. Inner ring rotation type (for non-driven wheels):Theflanges are fixed to the car body. Hub spindles are pressedinto the inner rings and fixed with nuts. Inner ring rotation type (for driven wheels):The flangesare fixed to the axle housing. Wheel hubs and drive shaftsare engaged to the inner all of the HUB II types, the initial axial clearance isproperly pre-set for the preload to fall within the specifiedrange after mounting, similar to the HUB uses bearing reference for hub unit Bearings clarifying boundary dimensions, types, and specification codes.

8 Below areexamples of bearing reference:Serial No. Material codeHUB II (Tapered roller Bearings )Example: KWH5401y2 Bore diameter 54 mmSerial codeMaterial codeHUB II (Ball Bearings )Example: BWK2704D2ay2 Bore diameter 27 mmHub unit Bearings1-3. HUB II87 Outer ring rotation typefor non-driven wheelsInner ring rotation typefor non-driven wheelsInner ring rotation typefor driven wheelsOuter ring rotation type for non-driven wheelsInner ring rotation type for non-driven and driven wheelsFlanged outer ringInner ringSealBallCageFlanged outer ringSealBallSealInner ringCageHUB IIIF langed outer ringHub boltFlanged inner ringSealCageInner ringBallHub capFlanged outer ringHub boltInner ringNutHub capSealFlanged inner ringCageBallHub boltFlanged inner ringFlanged outer ringSealBallInner ringCageSealNSK uses bearing reference for hub unit Bearings clarifying boundary dimensions, types, and specification codes.

9 Below areexamples of bearing reference:For HUB III, NSK uses proprietary bearing -type designationssuch as BWKH for ball Bearings . The HUB III configurationis a BWD HUB I with flanged inner and outer rings. Outer ring rotation type (for non-driven wheels):Wheels and brake disks are mounted at the outer ringflanges. The inner ring flanges are mounted on the car body,and the preload is pre-adjusted. Inner ring rotation type (for non-driven wheels):Wheels and brake disks are mounted at the inner ringflanges. The outer ring flanges are mounted on the car body,and the preload is pre-adjusted. Inner ring rotation type (for driven wheels): Wheelsand brake disks are mounted at the inner ring splined bore allows Bearings to be engaged to the CVJshaft end.

10 The outer ring flanges are fixed at the axlehousing. The initial axial clearance is properly pre-set for thepreload to fall within the specified range after the nuts arefastened. Hub unit BearingsMaterial codey5 Serial integralHUB III (Ball Bearings )Example: BWKH68S01 Ball pitch diameter 68 mm1-4. HUB III109 BWK (Ball Bearings )Inner ring rotation type for non-driven wheelsOuter ring rotation type for non-driven wheelsBWKH (Ball Bearings )Inner ring rotation type for driven wheelsSerial codeHUB III (Ball Bearings )Example: BWKH5202y5 Ball pitch diameter 52 mm2. Selection of Hub unit BearingsWhile higher performance is demanded for hub unit Bearings ,the constraints and conditions of their application arebecoming increasingly diverse. The selection of optimumbearing types satisfying such constraints and conditionsrequires the examination of various aspects.