24V DC Cooling Fan bearing system

"24V DC Cooling Fan" bearing system is generally what is it? Recommend the best selection of a ball bearing, the life of the hot air fan because the fan is usually dependent on the reliability of its bearing, ball bearing systems have been shown to have high efficiency and low heat characteristics. "24V DC Cooling Fan" rolling friction ball bearing genera, metal beads by rolling contact surface is small, the friction coefficient is small; and oil-bearing for sliding friction, a large contact surface, after long-term use, the oil will be volatile, bearing easy to wear, friction coefficient big, big noise late, short life. Good "24V DC Cooling Fan" in addition to ventilation volume, high pressure outside, reliability is very important bearing in the form of a fan used in this very important quality.