These components can be readily connected by lines of any length or
They can be separated and installed in small, unused, and
Large, unoccupied areas for the hydraulic
system are unnecessary; in short, special space requirements are
reduced to a minimum.
The hydraulic system weighs remarkably little in
comparison to the amount of work it does. A mechanical or electrical
system capable of doing the same job weighs considerably more. Since
nonpayload weight is an important factor on aircraft, the hydraulic
system is ideal for aviation use.
Self-Lubricating. The majority of the parts of a hydraulic system
operate in a bath of oil.
Thus, hydraulic systems are practically
The few components that do require periodic
lubrication are the mechanical linkages of the system.
Low Maintenance Requirements.
Maintenance records consistently
show that adjustments and emergency repairs to the parts of hydraulic
systems are seldom necessary.
The aircraft time-change schedules
specify the replacement of components on the basis of hours flown or
days elapsed and require relatively infrequent change of hydraulic
The word "force," used in a mechanical sense, means a push or pull.
Force, because it is a push or pull, tends to cause the object on
which it is exerted to move.
In certain instances, when the force
acting on an object is not sufficient to overcome its resistance or
drag, no movement will take place.
In such cases force is still
considered to be present.
Direction of Force.
Force can be exerted in any direction.
may act downward: as when gravity acts on a body, pulling it towards
A force may act across: as when the wind pushes a boat
across the water. A force can be applied upwards: as when an athlete
throws (pushes) a ball into the air.
Or a force can act in all
directions at once: as when a firecracker explodes.
expressed by means of a single measurement.
In the United States,
the "pound" is the unit of measurement of force.
For example, it
took 7.5 million pounds of thrust (force) to lift the Apollo moonship
off its launch pad.
Hydraulic force is measured in the amount of
pounds required to displace an object within a specified area such as
in a square inch.