The load varies in discrete steps over given parts of the duty cycle.
Calculate the equivalent load from: P = {P_a^p.a/100 + P_b^p.b/100 + P_c^p.c/100 + . . .}^1/p

where a b c, are proportions of the duty cycle at loads P_a P_b P_c respectively and p, the bearing life exponent is 3.0 for ball bearings and 3.333 for roller bearings.

If the load cycles continuously:
i) Plot for one complete cycle the value of P_v^p against time, where P_v is the varying load and and p, the bearing life exponent (see previous paragraph):

ii) Estimate the average value of P_v^p

iii) Steady Load Equivalent (P) is given by P= { P_v^paverage}^(1/p)