Machinery's Handbook, 31st Edition
2496 Ball and Roller Bearings Table 35. f o for Calculating Static Load Rating for Ball Bearings cos d D m α Radial and Angular Contact Groove Type Radial Self-Aligning Thrust Metric a Inch b Metric a Inch b Metric a Inch b 0.46 7.1 1030 2.8 399 23.5 3400 0.47 6.9 1000 2.8 404 22.9 3320 0.48 6.7 977 2.8 410 22.4 3240 0.49 6.6 952 2.9 415 21.8 3160 0.50 6.4 927 2.9 421 21.2 3080 a Use to obtain C o or C oa in newtons when D is given in mm. b Use to obtain C o or C oa in pounds when D is given in inches. Note: Based on modulus of elasticity = 2.07 × 10 5 megapascals (30 × 10 6 pounds per square inch) and Poisson’s ratio = 0.3. Radial Roller Bearings: The magnitude of the static load rating C o in newtons (pounds) for radial roller bearings is found by the formulas: (22a) (22b) where D = roller diameter, mm (inches); mean diameter for a tapered roller and major diameter for a spherical roller d m = mean pitch diameter of the roller complement, mm (inches) i = number of rows of rollers in bearing Z = number of rollers per row l eff = effective length, mm (inches); overall roller length minus roller chamfers or minus grinding undercuts at the ring where contact is shortest α = nominal contact angle, degrees Radial Roller Bearing Combinations: The static load rating for two similar single row roller bearings mounted side by side on the same shaft such that they operate as a unit is two times the rating of one single row bearing. The static radial load rating for two or more similar single row roller bearings mounted side by side on the same shaft such that they operate as a unit (duplex or stack mounting) in “tandem” arrangement, properly manufactured and mounted for equal load distribution, is the number of bearings times the rating of one single row bearing. Thrust Roller Bearings: The magnitude of the static load rating C oa in newtons (pounds) for thrust roller bearings is found by the formulas: (23a) ( ) cos d D iZl D 44 1 m eff α = − c m cos C metric o α ( ) cos d D iZl D 6430 1 m eff α − c m cos C inch o α = ( ) cos d D Zl D 220 1 m eff α − c m sin C metric oa α = Table 35. (Continued) f o for Calculating Static Load Rating for Ball Bearings
cos d D Zl D 32150 1 eff α − c m
sin
(
inch
)
C
=
α
(23b)
oa
m
where the symbol definitions are the same as for Formulas (22a) and (22b). Thrust Roller Bearing Combination: The static axial load rating for two or more simi- lar single direction thrust roller bearings mounted side by side on the same shaft such that they operate as a unit (duplex or stack mounting) in “tandem” arrangement, properly manufactured and mounted for equal load distribution, is the number of bearings times the rating of one single direction bearing. The accuracy of this formula decreases in the case of single direction bearings when F r > 0.44 F a cot α , where F r is the applied radial load in newtons (pounds) and F a is the applied axial load in newtons (pounds).
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