Loading ramps.
Folding pylons.
Winch hoists.
CHARACTERISTICS OF HYDRAULIC SYSTEMS
Hydraulic systems have many desirable features.
However, one
disadvantage is the original high cost of the various components.
This is more than offset by the many advantages that make hydraulic
systems the most economical means of power transmission.
The
following paragraphs discuss some of the advantages of hydraulic
systems.
Efficiency.
Discounting any losses that can occur in its
mechanical linkage, practically all the energy transmitted through a
hydraulic system is received at the output end -- where the work is
performed.
The electrical system, its closest competitor, is 15
percent to 30 percent lower in efficiency.
The best straight
mechanical systems are generally 30 percent to 70 percent less
efficient than comparable hydraulic systems because of high inertia
factors and frictional losses. Inertia is the resistance to motion,
action, or change.
Dependability.
The hydraulic system is consistently reliable.
Unlike the other systems mentioned, it is not subject to changes in
performance or to sudden unexpected failure.
Control Sensitivity.
The confined liquid of a hydraulic system
operates like a bar of steel in transmitting force.
However, the
moving parts are lightweight and can be almost instantaneously put
into motion or stopped.
The valves within the system can start or
stop the flow of pressurized fluids almost instantly and require very
little effort to manipulate. The entire system is very responsive to
operator control.
Flexibility of Installation.
Hydraulic lines can be run almost
anywhere. Unlike mechanical systems that must follow straight paths,
the lines of a hydraulic system can be led around obstructions. The
major components of hydraulic systems, with the exception of power-
driven pumps located near the power source, can be installed in a
variety of places.
The advantages of this feature are readily
recognized when you study the many locations of hydraulic components
on various types of aircraft.
Low Space Requirements.
The functional parts of a hydraulic
system are small in comparison to those of other systems; therefore,
the total space requirement is comparatively low.
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