INTRODUCTION TO FLUID POWER
Fluid power is a term which was created to
include the generation, control, and application
of smooth, effective power of pumped or
compressed fluids (either liquids or gases) when
this power is used to provide force and motion
to mechanisms. This force and motion maybe in
the form of pushing, pulling, rotating, regulating,
or driving. Fluid power includes hydraulics, which
involves liquids, and pneumatics, which involves
gases. Liquids and gases are similar in many
respects. The differences are pointed out in the
appropriate areas of this manual.
This manual presents many of the funda-
mental concepts in the fields of hydraulics and
pneumatics. It is intended as a basic reference for
all personnel of the Navy whose duties and
responsibilities require them to have a knowledge
of the fundamentals of fluid power. Conse-
quently, emphasis is placed primarily on the
theory of operation of typical fluid power systems
and components that have applications in naval
equipment. Many applications of fluid power are
presented in this manual to illustrate the functions
and operation of different systems and com-
ponents. However, these are only representative
of the many applications of fluid power in naval
equipment. Individual training manuals for each
rate provide information concerning the applica-
tion of fluid power to specific equipment for
which the rating is responsible.
A brief summary of the contents of this
training manual is given in the following
Chapter 2 covers the characteristics of liquids
and the factors affecting them. It also explains
the behavior of liquids at rest, identifies the
characteristics of liquids in motion, and explains
the operation of basic hydraulic components.
Chapter 3 discusses the qualities of fluids
acceptable for hydraulic systems and the types of
fluids used. Included are sections on safety
precautions to follow when handling potentially
hazardous fluids, liquid contamination, and
control of contaminants.
Chapter 4 covers the hydraulic pump, the
component in the hydraulic system which
generates the force required for the system to
perform its design function. The information
provided covers classifications, types, operation,
and construction of pumps.
Chapter 5 deals with the piping, tubing and
flexible hoses, and connectors used to carry fluids
Chapter 6 discusses the classification, types,
and operation of valves used in the control of
flow, pressure, and direction of fluids.
Chapter 7 covers the types and purposes of
sealing devices used in fluid power systems,
including the different materials used in their
construction. Additionally, the guidelines for
selecting, installing, and removing O-rings are
Chapter 8 discusses the operation of devices
used to measure and regulate the pressure of fluids
and to measure the temperature of fluids.
Chapter 9 describes the functions and types
of reservoirs, strainers, filters, and accumulators,
and their uses in fluid power systems.
Chapter 10 discusses the types and operation
of actuators used to transform the energy
generated by hydraulic systems into mechanical
force and motion.
Chapter 11 deals with pneumatics. It discusses
the origin of pneumatics, the characteristics and
compressibility of gases, and the most commonly
used gases in pneumatic systems. Also, sections
are included to cover safety precautions and the
potential hazards of compressed gases.
Chapter 12 identifies the types of diagrams
encountered in fluid power systems. This chapter
also discusses how components of chapters 4, 5,
6, 8, 9, and 10 are combined to form and operate
together as a system.
A glossary of terms commonly used in fluid
power is provided in appendix I. Appendix II
provides symbols used in aeronautical mechanical