18 Fluid Power
Mining companies use fluid power both in
open-pit and underground operations. Spectacular
examples of an application in this industry are the
huge shovels used in coal strip mining operations.
These shovels remove the overburden from veins of
coal that are near the surface. Some of these shovels
are several stories high and they can remove mul-
tiple cubic yards of material during each pass of
the scoop. The shovels use large numbers of fluid
power systems and circuits for movement and con-
trol. Other open-pit mining operations use more
standard front-end loader and truck designs for
loading and moving ore. In addition, many fluid
power applications, both pneumatic and hydrau-
lic, can be found in mine drilling, crushing, and
material-handling equipment. Fluid power appli-
cations are especially desirable in underground
mining locations. Accumulations of gas may pro-
duce potentially explosive conditions, limiting or
preventing the use of electrical devices.
Land, sea, and air defense forces use fluid
power to assist in moving personnel, supplies,
and equipment to support their operations. The
military makes use of a full range of fluid power
components and circuits. Many of these parallel
civilian commercial applications, but others are
highly specialized and are not directly duplicated
in commercial applications. Hundreds of applica-
tions exist, ranging from power-assisted steering
of land vehicles to the precision positioning of
rocket launchers for air defense, Figure 1-5.
Fluid Power Systems
Fluid power is a highly versatile power trans-
mission system, as illustrated by the range of
applications discussed earlier in this chapter. No
system, however, is entirely suitable for all applica-
tions. All power-transmission systems have char-
acteristics that are desirable in one application, but
turn into disadvantages in other situations. A sys-
tem cannot have every desired advantage without
disadvantages. Understanding system characteris-
tics as well as what is needed for a particular result
will help in producing an effective and efficient
application.
The range of applications that use fluid power
makes the development of a simple list of advan-
tages and disadvantages difficult, since examples
that do not “fit” can easily be found. This problem
Figure 1-4. Fluid power applications have been
used during the manufacture or processing of
most consumer products today. This carnival ride
makes extensive use of fl uid power. (Peter Hansen/
Shutterstock)
Figure 1-5. Complex defense systems make exten-
sive use of fl uid power. (©2007 Jupiterimages and
its licensors. All rights reserved.)