Machinery's Handbook, 31st Edition
2498 Ball and Roller Bearings load is that calculated, static centric axial load which produces a maximum contact stress acting at the center of contact of a uniformly loaded rolling element equal in magnitude to the maximum contact stress in the actual condition of loading. Radial Roller Bearings: The magnitude of the static equivalent radial load P o in newtons (pounds) for radial roller bearings under combined radial and thrust loads is the greater of:
P X F Y F o o r o a = + P F o r =
(27) (28)
where X o = radial factor given in Table 37 Y o = axial factor given in Table 37
F r = applied radial load, newtons (pounds) F a = applied axial load, newtons (pounds) Table 37. Values of X o and Y o for Computing Static Equivalent Radial Load P o for Self-Aligning and Tapered Roller Bearings
Single Row a
Double Row
X o 0.5
Y o
X o
Y o
Bearing Type
Self-Aligning and Tapered α ≠ 0
1
0.22 cot α
0.44 cot α
a P o is always ≥ F r . The static equivalent radial load for radial roller bearings with α = 0 ° and subjected to radial load only is P or = F r . Note: The ability of radial roller bearings with α = 0 ° to support axial loads varies considerably with bearing design and execution. The bearing user should therefore consult the bearing manufac turer for recommendations regarding the evaluation of equivalent load in cases where bearings with α = 0 ° are subjected to axial load. Radial Roller Bearing Combinations: When calculating the static equivalent radial load for two similar single row angular contact roller bearings mounted side by side on the same shaft such that they operate as a unit (duplex mounting) in “back-to-back” or “face- to-face” arrangement, use the X o and Y o values for a double row bearing and the F r and F a values for the total loads on the arrangement. When calculating the static equivalent radial load for two or more similar single row angular contact roller bearings mounted side by side on the same shaft such that they oper ate as a unit (duplex or stack mounting) in “tandem” arrangement, use the X o and Y o values for a single row bearing and the F r and F a values for the total loads on the arrangement. Thrust Roller Bearings: The magnitude of the static equivalent axial load P oa in newtons (pounds) for thrust roller bearings with contact angle α ≠ 90 ° , under combined radial and thrust loads is found by the formula: (29) where F a = applied axial load, newtons (pounds) F r = applied radial load, newtons (pounds) α = nominal contact angle, degrees The accuracy of this formula decreases for single direction thrust roller bearings when F r > 0.44 F a cot α . Thrust Roller Bearing Combinations: When calculating the static equivalent axial load for two or more 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, use the F r and F a values for the total loads acting on the arrangement. . tan P F F 23 oa a r α = +
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