Conclusion

I think that it is clear that plain and rolling bearings depend for their success on being made accurately and being continuously lubricated with a lubricant with appropriate properties for the application. It seems that stiffness comes from using small clearances and I understand that high performance racing engines cannot be turned over at all if they are cold. 

 

I did not describe roller bearings because this is a book on the use of fluids in engineering and not about mechanical design but it seems to me that a great range of roller bearings have been designed although invented might be a better word. They must all, in their  final form, be the outcome of testing.