LARGE BEARINGS

Technical Data Deep Groove Ball Bearings Angular Contact Ball Bearings Cylindrical Roller Bearings Tapered Roller Bearings Spherical Roller Bearings Thrust Bearings Bearings for Special Applications Catalog List & Appendix Table

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LARGE BEARINGS

TECHNICAL DATA CONTENTS Bearing life ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯ABasic rated life and basic dynamic load rating ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯AAdjusted life rating factor ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯ABasic static load rating ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯AAllowable static equivalent load ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯A- 2. Bearing Load Calculation ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯A- 8 2.1 Load acting on shafts ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯A- 8 2.2 Mean load ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯A- 8 2.3 Equivalent load ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯A- 9 3. Bearing Tolerances ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯A-11 3.1 Dimensional accuracy and running accuracy ⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯⋯A-11 3.2 Limits...

●Load Rating and Life 1. Load Rating and Life 1.1 Bearing life C : Basic dynamic rated load, N (Cr: radial bearings, Ca: thrust bearings) P : Equivalent dynamic load, N (Pr: radial bearings, Pa: thrust bearings) Even in bearings operating under normal conditions, the surfaces of the raceway and rolling elements are constantly being subjected to repeated compressive stresses which cause flaking of these surfaces to occur. This flaking is due to material fatigue and will eventually cause the bearings to fail. The effective life of a bearing is usually defined in terms of the total number of revolutions...

●Load Rating and Life 1.3.2 Life adjustment factor for material a2 The life of a bearing is affected by the material type and quality as well as the manufacturing process. In this regard, the life is adjusted by the use of an a2 factor. The basic dynamic load ratings listed in the catalog are based on NTN's standard material and manufacturing processes, therefore, the adjustment factor a2=1. When special materials or processes are used the adjustment factor can be larger than 1. NTN bearings can generally be used up to 120˚C. If bearings are operated at a higher temperature, the bearing must...

Life adjustment value a3 ●Load Rating and Life 1.5 Allowable static equivalent load Generally the static equivalent load which can be permitted (See Section 2.3.2 page A-9) is limited by the basic static rated load as stated in Section 1.4. However, depending on requirements regarding friction and smooth operation, these limits may be greater or lesser than the basic static rated load. In the following formula (1.9) and Table 1.2 the safety factor So can be determined considering the maximum static equivalent load. So =Co／Po…（1.9） where, So : Safety factor Co : Basic static rated load, N (radial...

●Bearing Load Calculation 2. Bearing Load Calculation To compute bearing loads, the forces which act on the shaft being supported by the bearing must be determined. These forces include the inherent dead weight of the rotating body (the weight of the shafts and components themselves), loads generated by the working forces of the machine, and loads arising from transmitted power. where: For ball bearings For roller bearings It is possible to calculate theoretical values for these loads; however, there are many instances where the load acting on the bearing is usually determined by the nature of...

●Bearing Load Calculation (4) Sinusoidal fluctuating load The mean load, Fm, can be approximated by formulas (2.5) and (2.6). (2) Dynamic equivalent axial load As a rule, standard thrust bearings with a contact angle of 90˚ cannot carry radial loads. However, self-aligning thrust roller bearings can accept some radial load. The dynamic equivalent axial load for these bearings is given in formula (2.8). Pa＝Fa＋1.2Fr………………（2.8） where, Pa：Dynamic equivalent axial load, N Fa：Actual axial load, N Fr ：Actual radial load, N Provided that Fr / Fa ≦ 0.55 only. 2.3.2 Static equivalent load The static equivalent...

●Bearing Tolerances 3. Bearing Tolerances Running accuracy Running accuracy constitutes the acceptable values for inner and outer ring radial runout and axial runout, inner ring side runout, and outer ring outer diameter runout. Allowable rolling bearing tolerances have been established according to precision classes. JIS Class 0 corresponds to normal precision class bearings, and precision becomes progressively higher as the class number becomes smaller; i.e., Class 6 is less precise than Class 5, which is less precise than Class 4, and so on. Table 3.1 indicates which standards and precision...

●Bearing Tolerances Table 3.3 Tolerance for radial bearings (Except tapered roller bearings) Table 3.3 (1) Inner rings  Nominal   bore  diameter Single radial plane bore diameter variation Single plane mean bore diameter deviation            ∆dmp max diameter series 0,1 max diameter series 2,3,4 class class class class class class class class class class class class class class class 0 6 5 4 2 0 6 5 4 2 0 6 5 4 2 1 The dimensional difference ∆ds of bore diameter to applied for class 4 and 2 is the same as the tolerance of dimensional difference ∆dmp of average bore diameter. However, the dimensional...

●Bearing Tolerances Mean single plane bore diameter variation Inner ring radial runout Face runout with bore Inner ring axial runout (with side) Inner ring width deviation ∆Bs normal class class class class class 0 6 5 4 2 class class class class class 0 6 5 4 2 class class class 5 4 2 class class class 5 4 2 Inner ring width variation class 2 class 0,6 class 5,4 class class class class class 0 6 5 4 2 2 To be applied to deep groove ball bearing and angular contact ball bearings. 3 To be applied to individual raceway rings manufactured for combined bearing use. Mean single plane outside diameter...