The brakes on your car, the lift in the mechanics shop and
standard construction machinery such as front end loaders, back hoes, and bull dozers all require
hydraulics instrumentation to perform their function. In addition to this, all sorts of industrial
cutters, presses, folders and a substantial amount of manufacturing machinery
depend on hydraulics. Hydraulic
technology is pretty important to our standard of living seeing as how we
depend on it in so many ways to perform many tasks for which we either directly
or indirectly rely upon.
Hydraulic technology largely is dependent on the fairly good
approximation that liquids are incompressible.
This means that if you put a liquid under a great deal of pressure, it
will not shrink but will take up the same amount of volume it had prior to
being placed under pressure. Hydraulic
fluids also have to be used inside of moving parts and not leak through high
pressure gaskets without breaking down itself or anything else through chemical
processes and so commercial hydraulic fluids are designed to maximize these
desirable qualities in the fluid.
The process used in hydraulic technology starts with recognizing
that when put under pressure, hydraulic fluid has an extremely small shrinkage
which takes place. This means that if a
volume is completely filled with hydraulic fluid, if one spot touching that
liquid is caused to pressurize the liquid, that pressure is felt throughout the
entire liquid.
Consider a sealed U tube filled with fluid, if one end of
that tube was a piston, you could push on the piston to apply pressure to the
entire liquid. So even if the piston had
only a surface area of a square inch and the entire tube had an area of 100
square inches, that entire larger area of 100 square inches will feel the same
pressure that was applied from the 1 square inch piston.
If the second side of the U tube also had a piston attached,
that piston would feel any pressure applied by the first piston. If the first piston still had only a 1 square
inch surface area touching the liquid, if the second piston had a 100 square
inch area, then putting a pound of pressure on the first piston of 1 square
inch area will cause a full pound of pressure per inch on the larger 100 square
inch piston. This device is now a fully
functional hydraulic lift, the 1 pound of pressure on the small piston applied
a full pound of pressure on every inch of the large 100 square inch piston
meaning that the larger piston could now move 100 pounds instead of the 1 pound
input pressure applied.
The difference is compensated by the amount of distance each
piston moves. If the small piston moves
one inch in to apply the pressure, the larger piston will only move a hundredth
of an inch to lift a full one hundred pounds.
So the trade off is in that a small pressure over a long distance can
result in large pressure over a very small distance (such as from your brake
pedal to the brakes on your car).
In this way, a hydraulic system can convert a small force
(over a long distance) into a very large force (over a very small
distance).
