Fluid bearing
（重定向自Fluid film lubrication）
![A hydrostatic bearing has two surfaces which has a fluid forced, via a restrictive orifice, in between the surfaces so that it keeps them apart. If the gap between the surfaces reduces then the outflow via the edges of the bearing is reduced and the pressure goes up, forcing the surfaces apart again very strongly, giving excellent control of the gap and giving low friction.](/Images/godic/202501/13/Hydrostatic_bearing_diagram.svg3637.png")
![Air bearings used to provide linear and rotational motion](/Images/godic/202501/13/Collection_of_air_bearings_from_Specialty_Components3637.jpg")
Fluid bearings are bearings that support their loads solely on a thin layer of liquid or gas.
They can be broadly classified into two types: fluid dynamic bearings and hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and the pressurization is done by a pump. Hydrodynamic bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces.