Thrust Bearings

Thrust BearingsSingle direction thrust ball bearingsSpherical roller thrust bearingsThese bearings are designed primarily to support axialloads at contact angles between 30˚ and 90˚. Just as withradial bearings, these bearings differ according to the type ofrolling element they use: there are thrust ball bearings thatuse balls and thrust roller bearings that use rollers.The configuration and characteristics of each type ofbearing are given.With thrust bearings, it is necessary to supply an axialpreload in order to prevent slipping movement between thebearing's rolling elements and raceways. For more detailedinformation on this point, please refer to the materialconcerning bearing preload on page A-62.1. Single direction thrust ball bearingsAs shown in Diagram 1, the steel balls of single directionthrust ball bearings are arranged between a pair of shafthousing washers (bearing shaft washer and housing shaftwasher), and the normal contact angle is 90˚. Axial loads canTable 1 Standard cage types for single direction thrust ball bearingsMoldedresin cagePressedcageBearingseries 511 512 513 514511005110751108511525120051207512085122451305513205140551415be supported in only one direction, radial loads can not beaccommodated, therefore these bearings are unsuitable forhigh speed operation.Table 1 lists the standard cage types for single directionthrust ball bearings.2. Spherical roller thrust bearingsJust like spherical roller bearings, the center of thespherical surface for spherical roller thrust bearings is thepoint where the raceway surface of the housing racewaydisc meets the center axis of the bearing. Since sphericalroller thrust bearings incorporate barrel-shaped rollers asrolling elements, they also have self-aligning properties.(See Diagram 2)Under normal load conditions, the allowable misalignmentis 1˚ to 2˚, although this will vary depending upon thebearing's dimension series.These bearings use machined copper alloy cages and aguide sleeve is attached to the inner ring to guide the cage.The axial load capacity of these bearings is high, and acertain amount of radial load can also be accommodatedwhen the ring is in an axially loaded state. However, it isnecessary to operate these bearings where the loadcondition meet Fr/Fa0.55.These bearings have some spots where lubricantcannot enter such as the gap between the cage andguide sleeve. It is necessary to use oil lubrication evenin low speed operation.Machinedcage51156511/530512265126051322513405141651420Note: Due to their material properties, molded resin cages can not beused in applications where temperatures exceed 120˚C.misalignmentangleDiagram 1. Single direction thrust ball bearing(with pressed cage)Diagram 2. Spherical roller thrust bearingsB-255

Thrust Bearings3. Cylindrical roller thrust bearingsThrust bearings incorporating cylindrical rollers areavailable in single row, double row, triple row, and four rowvarieties. (See Diagram 3) NTN Engineering offers the 811,812 and 893 series of standard series bearings that conformto dimension series 11, 12 and 93 prescribed in JIS, as wellas other special dimensions.Cylindrical roller thrust bearings are able to receive axialloads only, and have high axial rigidity which makes themwell suited for heavy axial loads. Needle roller bearinginformation for series 811, 812, and 893 is also listed in thedimension tables.Furthermore, bearings with dimensions not listed in thedimension tables are also manufactured. Contact NTNEngineering for more information.4. Tapered roller thrust bearingsAlthough not listed in the dimension tables, tapered rollerbearings like those in Diagram 4 are also manufactured.Contact NTN Engineering for more detailed information.Diagram 4. Tapered roller thrust bearingsDiagram 3. Double row cylindrical roller thrust bearingsB-256

Thrust BearingsB-257