ABSTRACT
The term “hydraulic” derives from the Greek words hydro and aulos, meaning water and pipe, respectively. Hydraulics is a branch of engineering science that deals with transmission of power under consideration of the static and dynamic behavior of fluids. Hydraulic systems were widely known and used for centuries; however, one had to wait until 1647 before the fundamental physical and mathematical rules were articulated by a brilliant young French scientist, Blaise Pascal. The most common types of hydraulic pumps are internal gear pumps, vane pumps, and piston pumps. Hydraulic fluids differ with regard to viscosity and viscosity retention, as well as protection against wear, cavitation, and corrosion. Hydraulic fluids must be practically incompressible and must flow readily at all operating temperatures. Synthetic ester-based hydraulic fluids were first mentioned at the 1937 Zurich Aviation Congress. Numerous base oil chemistries are used to formulate hydraulic fluids.
