Speeds 
The calculation of reference speeds is standardised in 
Limiting speed 
The 
The limiting speeds indicated in the product tables must not be exceeded even under favourable operating conditions without prior consultation with Schaeffler. 
Thermal speed rating 
The thermal speed rating is not a speed limit for the application of a bearing. It is primarily for the purpose of comparing the speed suitability of different bearing types under defined reference conditions. 
A speed limit taking account of the thermal balance can be calculated using the thermally safe operating speed. 
Reference conditions 
The reference conditions are based on the normal operating conditions of the most significant bearing types and sizes. 
They are defined as follows in 

for radial bearings, bearing seat Ar ≦ 50 000 mm2➤ Equation: 
for radial bearings, bearing seat Ar ＞ 50 000 mm2➤ Equation: 
for axial bearings, bearing seat Ar ≦ 50 000 mm2➤ Equation: 
for axial bearings, bearing seat Ar ＞ 50 000 mm2➤ Equation: 
The following lubricants and lubrication methods are suitable: 

Thermally safe operating speed 
The thermally safe 

The permissible operating temperature determines the thermally safe 
The calculation method is not valid for: 


The 
Calculate thermally safe operating speed 

In order to calculate the thermally safe operating speed n_{ϑ} at a constant operating temperature ϑ, the frictional power generated and the total dissipated heat flow of the rolling bearing must be in equilibrium 

The generated frictional power of the rolling bearing is calculated using the total frictional torque 
The frictional power is equal to the dissipated heat flow 



The speed ratio f_{n} can be calculated by means of iteration or in the normal operating range of 
Figure 1 K_{L} = lubricant parameter K_{P} = load parameter 

The thermally safe operating speed n_{ϑ} is calculated by multiplying the thermal speed rating n_{ϑr} by the speed ratio f_{n} 

The lubricant parameter K_{L} is calculated in accordance with 

The load parameter K_{P} is calculated in accordance with 

Heat dissipation via the bearing seating surfaces is calculated in accordance with 
Figure 2 A_{S} = heatdissipating bearing seating surface Reference condition for axial bearings Reference condition for radial bearings 

Heat dissipation via the lubricant is calculated in accordance with 

