Machinery's Handbook, 31st Edition
Ball and Roller Bearings 2497 Ball Bearing Static Equivalent Load.— For ball bearings the static equivalent radial load is that calculated static radial load which produces a maximum contact stress equal in magnitude to the maximum contact stress in the actual condition of loading. The static equivalent axial load is that calculated static centric axial load which produces a maxi- mum contact stress equal in magnitude to the maximum contact stress in the actual condi- tion of loading. Radial and Angular Contact Ball Bearings: The magnitude of the static equivalent radial load P o in newtons (pounds) for radial and angular contact ball bearings under combined thrust and radial loads is the greater of:
P X F Y F o o r o a = + P F o r =
(24) (25)
where X o = radial load factor given in Table 36 Y o = axial load factor given in Table 36
F r = applied radial load, newtons (pounds) F a = applied axial load, newtons (pounds) Table 36. Values of X o and Y o for Computing Static Equivalent Radial Load P o of Ball Bearings
Single Row Bearings a
Double Row Bearings
Y o
Y o
X o
X
b
b
Contact Angle
o
RADIAL CONTACT GROOVE BEARINGS c , a
0.6
0.5
0.6
0.5
α = 0 °
ANGULAR CONTACT GROOVE BEARINGS
0.5 0.5 0.5 0.5 0.5 0.5
0.47 0.42 0.38 0.33 0.29 0.26
1 1 1 1 1 1
0.94 0.84 0.76 0.66 0.58 0.52
α = 15 ° α = 20 ° α = 25 ° α = 30 ° α = 35 ° α = 40 °
SELF-ALIGNING BEARINGS
…
0.5
1
0.22 cot α
0.44 cot α
o is always ≥ F r .
a P
b Values of Y
o for intermediate contact angles are obtained by linear interpolation.
c Permissible maximum value of F
a / C o (where F a is applied axial load and C o is static radial load
rating) depends on the bearing design (groove depth and internal clearance). Thrust Ball Bearings: The magnitude of the static equivalent axial load P oa in newtons (pounds) for thrust ball bearings with contact angle α ≠ 90 ° under combined radial and thrust loads is found by the formula: (26) where the symbol definitions are the same as for Formulas (24) and (25). This formula is valid for all load directions in the case of double direction ball bearings. For single direction ball bearings, it is valid where F r / F a ≤ 0.44 cot α and gives a satisfactory but less conservative value of P oa for F r / F a up to 0.67 cot α . Thrust ball bearings with α = 90 ° can support axial loads only. The static equivalent load for this type of bearing is P oa = F a . Roller Bearing Static Equivalent Load.— The static equivalent radial load for roller bearings is that calculated, static radial 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. The static equivalent axial . tan P F F 23 oa a r α = +
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