Page 15 of catalogue High precision bearings for combined loads of Schaeffler Technologies GmbH & Co. KG

Axial/radial bearings Axial Angular contact ball bearings
Limiting speeds
The bearings allow the limiting speeds nG given in the dimension Tables. The operating temperatures occurring are heavily dependent on the environmental conditions. Calculation is possible by means of a thermal balance analysis based on frictional torque data. If the environmental conditions differ from the specifications in relation to, for example, adjacent construction tolerances, lubrication, ambient temperature/heat dissipation or from operating conditions normal from machine Tools, checking must be carried out again. Please contact us. Once the bearings have been fitted and fully screw mounted, they are radially and axially clearance-free and preloaded. Temperature differences between the shaft and housing influence the radial bearing preload and thus the operating behaviour of the bearing arrangement. If the shaft temperature is higher than the housing temperature, the radial preload will increase proportionally, so there will be an increase in the rolling element load, bearing friction and bearing temperature. If the shaft temperature is lower than the housing temperature, the radial preload will decrease proportionally, so the rigidity will decrease to bearing clearance and wear will increase. The bearing frictional torque MRL is influenced primarily by the viscosity and quantity of the lubricant and the bearing preload. ■ The lubricant viscosity and quantity are dependent on the lubricant grade and operating temperature. ■ The bearing preload is dependent on the mounting fits, the geometrical accuracy of the adjacent parts, the temperature difference between the inner and outer ring, the screw tightening torque and the mounting situation (bearing inner ring axially supported on one or both sides). The frictional torques MRL in the dimension tables are statistically determined guide values for bearings with grease lubrication (measurement speed nconst = 5 min–1). Figure 12 shows measured frictional torques for mounting with an unsupported L-section ring for YRTSpeed. Deviations from the tightening torque of the fixing Screws will have a detrimental effect on the preload and the frictional torque.
22,5 Nm 20 17,5 15
MRL = frictional torque n = speed

Caution!

Bearing preload
Temperature differences

Frictional torque

Caution!

YRTSpeed 460

12,5 10 M RL 7,5 5 2,5 0 200 400 n

YRTSpeed 395 YRTSpeed 325 YRTSpeed 260 YRTSpeed 200

Figure 12 Frictional torques as guide values for YRTSpeed – statistically determined values from series of measurements

600

800

1000

1200 –11400 min

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Schaeffler Group Industrial

107 501a

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