Minimum, equivalent dynamic and equivalent static bearing loads
Minimum load

For additional information
Requisite minimum load
Frm = 0,02 C

Except for SKF Explorer bearings:
Frm = 0,017 C

Perform calculations
Equivalent dynamic bearing load

For additional information
Equivalent dynamic bearing load

Fa/Fr ≤ e
→ P = Fr + Y1 Fa

Fa/Fr > e
→ P = 0,67 Fr + Y2 Fa

Perform calculations

Equivalent static bearing load

For additional information
Equivalent static bearing load
P0 = Fr + Y0 Fa


basic dynamic load rating [kN] (→ product tables TDO and TDI designs)
calculation factor (→ product tables TDO and TDI designs)
Faaxial load [kN]
Frradial load [kN]
minimum radial load [kN]
Pequivalent dynamic bearing load [kN]
equivalent static bearing load [kN]
Y, Y0 ,Y1, Y2calculation factors (→ product tables TDO and TDI designs)
Comparative load ratings

For rolling mill applications, load ratings are not necessarily calculated according to ISO 281. Instead, they are often calculated by a different method based on a rating life of 90 million revolutions (500 r/min for 3 000 operating hours). These comparative load ratings are provided in the product tables because a direct comparison between the comparative and ISO load ratings is not possible, even if the comparative ratings are converted for 1 million revolutions (ISO life definition).

These comparative load ratings may not be used to calculate an ISO rating life. They may only be used together with the comparative rating life and equivalent load equations specified as follows:

LF10 = 90 (CF/PF)10/3


LF10h = (CF/PF)10/3 (1 500 000/n)


LF10comparative rating life [million revolutions]
LF10hcomparative rating life [operating hours]
CFcomparative dynamic load rating to give a rating life of 90 million revolutions [kN]
PFcomparative equivalent dynamic bearing load [kN] (→ table 1)
constant rotational speed [r/min]
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