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Fluid bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. [1] Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings.
Here a key goal of lubrication theory is to determine the pressure distribution in the fluid volume, and hence the forces on the bearing components. The working fluid in this case is often termed a lubricant. Free film lubrication theory is concerned with the case in which one of the surfaces containing the fluid is a free surface. In that case ...
The fluid film thickness is much less than the width and length and thus curvature effects are negligible. (i.e. h ≪ l {\displaystyle h\ll l} and h ≪ w {\displaystyle h\ll w} ). For some simple bearing geometries and boundary conditions, the Reynolds equation can be solved analytically.
In hydrostatic lubrication, external pressure is applied to the lubricant in the bearing to maintain the fluid lubricant film where it would otherwise be squeezed out. In hydrodynamic lubrication, the motion of the contacting surfaces, as well as the design of the bearing, pump lubricant around the bearing to maintain the lubricating film.
The oil pump is an internal combustion engine part that circulates engine oil under pressure to the rotating bearings, the sliding pistons and the camshaft of the engine. This lubricates the bearings, allows the use of higher-capacity fluid bearings and also assists in cooling the engine.
Class III: bearings made of materials that are the lubricant. These bearings are typically considered "self-lubricating" and can run without an external lubricant. Examples of the second type of bearing are Oilites and plastic bearings made from polyacetal; examples of the third type are metalized graphite bearings and PTFE bearings. [10]
Spherical roller thrust bearings offer the highest load rating density of all thrust bearings. [2] Fluid bearings, where the axial thrust is supported on a thin layer of pressurized liquid—these give low drag. Miba fluid film thrust bearing. Magnetic bearings, where the axial thrust is supported on a magnetic field.
Around 1890, the modern fluid bearing was invented, now universally used to support heavy water turbine spindles. As of 2002, fluid bearings appear to have a mean time between failures of more than 1300 years. Around 1913, Viktor Kaplan created the Kaplan turbine, a propeller-type machine. It was an evolution of the Francis turbine and ...