The effect of lubrication has been incorporated in the recommendations given. Selection can be made assuming a suitable lubrication as specified in the Bearing lubrication section. For some applications it may be necessary to consider the following factors in greater detail. In such cases the following revised equation for bearing life applies.

Ln_a = a1 x a2 x a3 x L₁₀
where Ln_a = adjusted life
a1 = factor for reliability
a2 = factor for material
a3 = factor for operating conditions

For reliability of 90% (L₁₀ life) and normal materials and operating conditions a1=a2=a3=1

For reliability greater than 90%, use value a1 as follows:

Values of a2 greater than1.0 may be obtained by the use of special steels.
V_a = lubricant viscosity in application
V_r = required lubricant viscosity for adequate lubrication at the operating temperature.

For values of V_a/V_r below 1.0, please consult our technical department.

For applications where (C_r/P<5) and other critical conditions, the viscosity of the lubricant must be considered, please consult our technical department.

The effect of elevated temperatures is considered below. Factor a3 is a factor for lubrication and is determined by the ratio V_a/V_r. To obtain advantages from improved steels, adequate lubrication is required; the factors a2 and a3 are therefore interdependent and can be replaced by the combined factor a23.

Temperature

The normal range for standard bearings is 32°F to 212°F (0° to 100°C). Where the temperature rise is mainly from the shaft, increased diametral clearance may be necessary and account taken of axial movement through expansion (EX) bearings.

Above 212°F/100°C, special consideration must be given to material, design, lubrication and seals. Above 250°F/120°C, to special heat treatment of the bearing parts is required. A reduction in radial capacity occurs at temperatures above 300°F(150°C), which can be seen below.

For temperatures above 212°F/ 100°Cor below 32°F(10°C), please consult our technical department.