Subtopic: Measurement of force, stress, torque, speed, displacement and acceleration on machine elements – shafts, couplings, keys, bearings and knuckle joints
Question Statement:
A rolling contact bearing is subjected to combined radial load $F_r$ and axial thrust load $F_a$. The equivalent dynamic radial load $P$ used in bearing life calculation is given by standard ISO formula:
Options:
(A) $P = X V F_r + Y F_a$
(B) $P = \sqrt{F_r^2 + F_a^2}$
(C) $P = F_r + F_a$
(D) $P = \frac{F_r F_a}{F_r + F_a}$
Answer Key:
A
Step-by-Step Solution & Explanation
- According to standard bearing design theory (ISO 281 / ASABE / Shigley):
$P = X V F_r + Y F_a$
where $X$ is the radial load factor, $V$ is the rotation factor ($V=1.0$ for inner ring rotating, $1.2$ for outer ring rotating), and $Y$ is the axial thrust factor depending on the ratio $F_a / (V F_r)$ relative to threshold parameter $e$.