"DC Fan" in addition to ventilation volume, high pressure outside, reliability is also very important, bearing fan used in this form is very important quality. Always use a high-speed fan ball bearing (Ball bearing) and low-speed fan using low-cost oil-bearing (Sleeve bearing). Oil bearing fan with only one bearing; and two ball bearing fans are required, single ball bearing, is "1 Ball + 1 Sleeve", oil bearing components with still. More advanced than the single ball double ball bearing is that Two Balls. Oil bearing life is typically 10,000 hours, 30,000 hours as a single ball, double ball bearing is more than 50,000 hours (ambient temperatures are set below 25 ℃ when). Oil-bearing fan used by the copper-based sintered powder made use of oil-bearing lubricant to be added in order to reduce the number of sliding friction, the lubricating oil lithium grease Stuttgart system modulation. With the long run, the oil inside the bearing will evaporate and dry, the friction coefficient increases, fan operation is affected, may appear abnormal sound, speed Pianman not even turn on. The ball bearing is replaced by rolling friction sliding friction, friction coefficient is small and easy to overcome the shortcomings of the friction coefficient of variation, and thus the operation stability, relatively longer life expectancy.