20 Fluid Power
Cost
The cost of fluid power systems ranges widely.
A variety of situations exist and a number of
solutions are available for each one. The solution
selected to solve the problem directly affects the
cost. Understanding system advancements, basic
characteristics of hydraulic and pneumatic sys-
tems, and knowing which standard components
are available are necessary to produce a system
that does the best job at the lowest cost.
The cost of system operation is a factor that
must be considered. Generally, pneumatic systems
are more expensive to operate than hydraulic sys-
tems. This cost can be directly associated with the
compression, conditioning, and distribution of
air. Careful maintenance to eliminate leakage can
greatly reduce operating cost.
Advantages and Disadvantages of
Fluid Power Systems
Fluid power systems have several advantages
and disadvantages when compared with mechani-
cal and electrical power transfer systems. Several
of the important advantages and disadvantages of
fluid power systems are presented in the next two
sections.
Advantages
The following list of advantages applies to both
hydraulic and pneumatic systems, except as noted.
■ An easy means of multiplying and controlling
force and torque.
■ Infinitely variable speed control for both lin-
ear and rotary motion.
■ Overloading the system simply stalls the actu-
ator without damage to the components.
■ Provides an easy means of accurately control-
ling the speed of machines and/or machine
parts.
■ Provides the ability to instantly stop and
reverse linear and rotary actuators with mini-
mal shock to the system.
■ Systems easily adapt to accommodate a range
of machine sizes and designs.
■ Systems readily adapt to external control
methods, including mechanical, pneumatic,
electrical, and electronic systems, Figure 1-8.
■ Systems can easily provide component
lubrication.
Figure 1-7. Pneumatics are commonly used where
high speeds and lightweight tools are needed.
(Photo: Atlas Copco)
Figure 1-8. Both hydraulic and pneumatic systems
can be readily adapted to external control systems,
including state-of-the-art electronic designs.
(Photo: Atlas Copco)