Most of rolling bearing have inner ring, outer ring, rolling elements and cage. Take locomotive as example, outer ring in housing and inner ring go with shaft. 

Different class for different application, mining machinery needs not high class bearing while machine tool bearing needs high class.

These bearings have different application per their own features itself. For CRB and ball bearing, they are ok for high speed such as vehicles, agriculture machine and construction machine etc. ; large CRB and TRB are for heavy load application such as wind mill gearboxes, machine tool, rolling mill, primary metal machine and construction machines etc. ; SRB is for harsh environment and relative heavy load application such as primary metal, rolling mill, cement and mining machinery. And we can say large size and outsize bearing is quite necessary and must for nation construction. 
Our large size and outsize bearing are serving leading edge industry, including:

· TBM cutter bearing 

· Wind mill industry 

· Primary metal industry 

· Mining machinery and Construction machinery 

· Large gearboxes

Most common rolling bearings are ball bearing, cylindrical roller bearing, taper roller bearing and spherical roller bearing etc. which is classified by roller geometry. As we can see ball bearing rolling element is sphere and cylindrical roller bearing roller is cylinder etc. If category according to dimension, then we have miniature bearing, small bearing, middle/small bearing, middle/large bearing, large size bearing and outsize bearing etc. 

Rolling bearing functions positioning and taking load, moreover release friction through rotation. Normally, decrease friction through rolling instead of sliding.