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Hydraulic fluid
Medium to transfer power in hydraulic machinery / From Wikipedia, the free encyclopedia
A hydraulic fluid or hydraulic liquid is the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water.[1] Examples of equipment that might use hydraulic fluids are excavators and backhoes, hydraulic brakes, power steering systems, automatic transmissions, garbage trucks, aircraft flight control systems, lifts, and industrial machinery.
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Hydraulic systems like the ones mentioned above will work most efficiently if the hydraulic fluid used has zero compressibility.