What are the advantages of hydraulic cooling fans

There are three main types of bearings for cooling fans, oil-impregnated bearings, hydraulic bearings (as shown in the figure below), and double ball bearings. In recent years, the use of hydraulic bearing-type cooling fans has increased. So, what are its advantages? 1. Low cost, much lower cost compared to double ball bearings 2. Quiet sound, bearing and shaft core are handled in a suspended state, almost no friction, there is lubricating oil in the middle, and the sound is very quiet 3. Long life, compared to oil-impregnated bearings In other words, the service life is slightly longer. 4. The appearance is beautiful. The label position is integrally formed. Unlike a ball bearing and an oil-impregnated bearing, there is a hole in the middle, and there is no leakage of oil like a cooling fan with an oil-impregnated bearing.