This guide will break down the details of the types of bearings fans have along with various information like life expectancy and noise level. 

 

Bearing System
Noise Level
Life Expectency
Environment Mounting   Cost 
Sleeve  Quietest  41,000 Hours Low Heat. Higher Shocks  Horizontally   Lowest  
Ball Louder 55,000 Hours Higher Heat. No Shocks
Any    Average 
One Ball One Sleeve Loudest 67,000 Hours Low Heat. Higher Shocks
Any    Average 
Dual Ball Quieter 67,000 Hours Higher Heat. No Shocks
Any   Highest