For some high-precision bearings

You need higher speeds (ie, high-speed machining centers or internal grinding), you need to find a different bearing solutions.
For some high precision bearing, its clutch bearing  requirements is very high, today we have to introduce a configuration problem on precision bearings.
Precision bearings spindle traditional application areas, according to different processes, machine tool spindle have different requirements. In general, the lathe spindle is used at lower speeds and larger cutting metal cutting load. This type of spindle are usually transmitted through the pulley or gear drive torque. This means that the load on the drive end shaft is quite large.