discovered by these two men regarding the effects of pressure and
temperature on fluids and gases in confined areas form the basis of
the principle of mechanical advantage; in other words, the "why and
how" of hydraulics.
This chapter explains to you the basic applications of hydraulics in
Army aviation and the characteristics of these systems.
explanations include detailed definitions of the terminology peculiar
to hydraulics with which you must be familiar to fully understand
In aviation, hydraulics is the use of fluids under pressure to
transmit force developed in one location on an aircraft or other
related equipment to some other point on the same aircraft or
Hydraulics also includes the principles underlying
hydraulic action and the methods, fluids, and equipment used in
implementing those principles.
HYDRAULIC AND HYDRAULICS
The word "hydraulic" is derived from two Greek words: "hydro" meaning
liquid or water and "aulos" meaning pipe or tubing.
therefore, is an adjective implying that the word it modifies is in
some major way concerned with liquids. Examples can be found in the
everyday usage of "hydraulic" in connection with familiar items such
as automobile jacks and brakes.
As a further example, the phrase
"hydraulic freight elevator" refers to an elevator ascending and
descending on a column of liquid instead of using cables and a drum.
On the other hand, the word "hydraulics" is the generic name of a
According to the dictionary "hydraulics" is defined as a
branch of science that deals with practical applications (such as the
transmission of energy or the effects of flow) of a liquid in motion.
USES OF HYDRAULICS ON ARMY AIRCRAFT
On fixed-wing aircraft, hydraulics is used to operate retractable
landing gear and wheel brakes and to control wing flaps and propeller
In conjunction with gases, hydraulics is used in the
Rotor and wheel brakes.
Flight control systems.