Chapter 1
Introduction to Fluid Power
The Fluid Power Field
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Objectives
 Define the terms fluid power, hydraulic system,
and pneumatic system
system.
 Explain the extent of fluid power use in current
society and provide several specific examples.
 List the advantages and disadvantages of fluid
power systems.
 Discuss scientific discoveries and applications
important to the historical development of the
fluid power industry.
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Definition of Fluid Power
 A fluid power system consists of a prime
mover turning a pump to pressurize a fluid,
which is transmitted through lines to an
actuator that performs work.
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Definition of Fluid Power
 Fluid power systems are generally grouped
under two broad classifications:
– Hydraulics
– Pneumatics
 Hydraulic systems generally use oil as the
system fluid
fluid, while pneumatic systems use
air.
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Fluid Power Systems
 Comparisons of hydraulic and pneumatic
systems may be done by analyzing:
–
–
–
–
–
Operating pressure
Accuracy of actuator movement
Actuator speed
Component weight
System cost
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Fluid Power Systems
 Hydraulic systems are accurate, operate at
high pressures, are slow, and have strong
components.
(Brand X)
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Fluid Power Systems
 Compared to hydraulic systems, pneumatic
systems:
– Are less accurate
– Are faster
– Have components that are lighter in weight
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Fluid Power Systems
 Advantages of both hydraulic and pneumatic
systems include easy control of:
–
–
–
–
Force
Torque
Speed
Direction of actuators
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History of Fluid Power
 The natural
movement of air and
water was used in the
earliest applications
of fluid power.
 Some industries still
use this natural
movement.
Glowimages
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History of Fluid Power
 Wind and watermills were used as prime
movers to provide power until well into the
Industrial Revolution, which occurred in the
eighteenth and nineteenth centuries.
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History of Fluid Power
 Early wind and watermills had very low
power outputs. The output was usually in
the 3 to 5 horsepower range, with an output
of 15 horsepower considered high.
 Historians feel that many early
machines/devices were developed and
operated using empirical knowledge, rather
than scientific theory.
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History of Fluid Power
 Archimedes is credited with the discovery
in the third century BC of the principle of
buoyancy. This is one of the earliest
recorded scientific theories.
 Scientists such as Pascal, Boyle, Charles,
Reynolds and others provided information
Reynolds,
that served as a theoretical base for the use
of fluids in scientific and industrial
applications.
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History of Fluid Power
 James Watt perfected
the steam engine, which
influenced many aspects
of the Industrial
Revolution including
fluid ppower components
p
and systems.
Comstock
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History of Fluid Power
 Accurate machining and the development of
effective sealing devices had a positive effect
on the early development of hydraulic presses.
Photo courtesy of Apple Rubber Products, Inc.
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History of Fluid Power
 Compact, self-contained power units, which
contained the prime mover, pump, and
reservoir, were developed in the early 1900s.
 These units had considerable influence on
the development of fluid power as we know
it today.
today
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History of Fluid Power
 Self-contained power units
Continental Hydraulics
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Fluid Power Today
 Fluid power
systems are used
extensively
throughout
business and
industryy today.
y
Glowimages
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Fluid Power Today
 Few products are not influenced in some
way by fluid power systems.
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Fluid Power Today
 Fluid power in various forms is widely
used in everyday life
life.
PhotoDisc
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Review Question
The physical components in a fluid power
system
t are usedd to
t _____, _____, andd _____
power to produce the desired results in an
application.
generate; transmit; control
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Review Question
Name six industries in which fluid power
applications
li ti
contribute
t ib t to
t daily
d il operations
ti
andd
long-term business success.
Manufacturing, transportation, mining,
agriculture, construction, and recreation.
(other answers are possible)
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Review Question
The pneumatic fluid power system is generally
considered
id d to
t be
b the
th mostt expensive
i to
t operate
t
because of the cost of _____, _____, and _____
the air.
compressing; conditioning; distributing
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Review Question
It is generally believed by historians that much
off the
th early
l development
d l
t off fluid
fl id power was
based on _____, rather than on an
understanding of scientific principles.
practical experimentation
experimentation, or tinkering
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Glossary
 Actuator
– A component used to convert the energy in
hydraulic fluid or compressed air into mechanical
linear or rotary motion.
 Archimedes
– The individual credited with the discovery
y of the
principle of buoyancy. The discovery was made in
the third century BC.
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Glossary
 Boyle, Robert
– A scientist of the 17th century identified as one of
the first to study the characteristics of gases.
 Charles, Jacques
– A French scientist of the late 18th and early 19th
centuries who is credited with developing
p ga
scientific law relating to the effect of temperature
on the volume of a gas.
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Glossary
 Fluid power
– Th
The transferring,
t
f i controlling,
t lli andd converting
ti off
energy using hydraulic and pneumatic systems.
 Hydraulics
– The study and technical application of liquids in
motion, especially oils and other blended liquids
used in industrial systems
systems.
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Glossary
 Pascal, Blaise
– A scientist of the early 17th century who is credited
with producing proof of many basic fluid principles.
 Pneumatics
– The study and technical application of air or other
gas in motion.
g
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Glossary
 Pump
– A hydraulic component turned by the prime mover
that produces fluid flow, which transmits energy
through the system.
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Glossary
 Reynolds, Osborne
– A scientist of the late 1800s who did extensive
development work in the fluid mechanics area.
Reynolds is credited with identification of the
principles of laminar and turbulent flow.
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Glossary
 Watt, James
– An inventor of the late 18th century who
extensively contributed to growth during the
Industrial Revolution. Watt is typically
identified as the inventor of the first practical
steam engine.
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