# What is Stribeck's equation to find static capacity?

Q.  Which of the following is a Stribeck's equation to determine basic static capacity of ball bearings?
(where d = roller diameter, L = roller length)

- Published on 23 Sep 15

a. KdLZ / 5
b. Kd2Z / 5
c. K2dL / 5Z
d. 5 Kd / Z

ANSWER: Kd2Z / 5

#### Discussion

• Sravanthi   -Posted on 01 Oct 15
• For ball bearings static basic capacity (Co) can be calculated using the formula Kd2Z / 5, where Z = number of balls.
• For straight roller bearings, Co = Kd LZ / 5 where L and d are diameter and length of rollers.

Stribeck's equation to determine basic static capacity of ball bearings is based on assumptions specified below:
1) After loading races retain their circular shape and are rigid.
2) Balls in in the bearings are equally spaced.

• AFBMA (Anti-friction Bearing Manufactures Association ) modified Stribeck's equation based on later experiences but Stribeck's equation is still used to determine basic static capacity of ball bearings.

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