PSAA Curriculum
Unit
Physical Science Systems
Problem Area
Energy and Power Systems
Hydraulic Power Transmission
Lesson
What are some specific applications for
hydraulics?
Make a list of equipment and the specific
applications of hydraulics.
Why are hydraulics a part of so many
pieces of agricultural and industrial
equipment?
Learning Objectives
Identify the components of a hydraulic
system and explain its operation.
Determine the efficiency of a hydraulic
power system.
Calculate the actual and ideal
mechanical advantages of a hydraulic
system.
Explain the common uses of hydraulic
systems on agricultural machines.
Terms
 Actual mechanical
advantage
 Area
 Circuit
 Efficiency
 Force
 Hydraulics
 Ideal Mechanical
Advantage
 Pascal’s Law
 Pressure
 Pump
 Reservoir
 Syringe
 Work
What are the basic components of a
hydraulic system and the role each
component plays in the system?
Hydraulics is the science of liquid
in motion.
Air is compressible but liquids
cannot be compressed.
A system that uses oil or another
type of liquid is known as a
hydraulic system.
What are the basic components of a
hydraulic system and the role each
component plays in the system?
 A basic idea behind any
hydraulic system is that when a
force is applied at one point, the
force is transmitted to another
point using an incompressible
fluid.
 The fluid is usually an oil and the
force usually multiplied during
the process.
Basic to any hydraulic system are:
A pump, which creates pressure for the
system.
A rotor or cylinder, which transfers the
hydraulic energy back into mechanical
energy in the form of rotary or linear
motion.
The cylinder in this lesson consists of a
disposable syringe to transmit the energy.
Basic to any hydraulic system are:
Lines, which transfer the hydraulic energy
from the pump to the rotor or cylinder and
return the energy to the pump.
A reservoir to store a supply of fluid.
Valves to control, or direct, the fluid and its
movement.
All the components make up the hydraulic
circuit that completes the loop.
Hydraulic Power Transmission
Laboratory Setup Diagram
Hydraulics (cont.)
 Pressure may be defined as the potential
energy of a fluid power system.
 Applying pressure to some unit area develops
force.
 Pressure is calculated by dividing the force by
the area.
 Applying a pressure of ten pounds to one square
inch area of a plunger in a hydraulic cylinder will
exert a pressure of ten pounds on each square
inch of the system.
Hydraulics (cont.)
Pascal’s Law states that pressure exerted
at any point on a confined static liquid is
transmitted with equal force on equal
areas at right angles to all surfaces.
Hydraulics (cont.)
The scientific definition for work involves
using a force to move an object.
In hydraulics force and work are inversely
proportional, meaning one must be
sacrificed for the other in the system.
Hydraulics (cont.)
In a hydraulic system involving two pistons,
when one piston is six times larger than the
other piston, a force applied to the smaller
piston will appear six times greater on the
larger piston, but the smaller piston will have
to travel six times farther in travel distance.
How is the efficiency for a hydraulic
system calculated? What factors affect
the efficiency of the system?
The efficiency of a system is usually
calculated by comparing the output to the
input of the system.
In a hydraulic system, efficiency is
determined by dividing the actual
mechanical advantage by the ideal
mechanical advantage and multiplying the
result by 100 to obtain a percentage of
efficiency.
Efficiency of the hydraulic system
Efficiency of the hydraulic system in the
experiment can be affected by various
factors, the most obvious being friction.
Efficiency of the hydraulic system
If the weights providing the force are not
properly placed and the force does not push
directly straight down on the hydraulic piston,
additional force can be exerted horizontally
between the plunger and cylinder wall.
This outward force will increase the effort
needed to lift the resistance and reduce the
efficiency, because the actual mechanical
advantage will be decreased.
How is actual mechanical advantage and
ideal mechanical advantage calculated for
a hydraulic system?
Ideal mechanical advantage is the
theoretical advantage that the system
would have if there were no outside
influences or limitations such as friction of
the fluid or the plungers against the walls
of the syringe or hydraulic piston.
Ideal advantage assumes that there is no
air present in the system and there are no
fluid leaks as well.
Ideal Mechanical Advantage
Ideal mechanical advantage in a hydraulic
system is determined by dividing the area
of the larger piston by the area of the
smaller piston.
Area of the piston is calculated by
squaring the diameter of the piston,
multiplying by pi (3.14) and dividing by 4.
Area is reported in square units such as
square inches or square centimeters.
Actual mechanical advantage
Actual mechanical advantage is the actual
advantage gained when all these limitations
and factors are considered by comparing the
loads placed on the system.
Actual mechanical advantage is determined by
dividing the resistance force by the effort force.
The resistance force is the object(s) attempting to
be moved by the hydraulic system.
What uses exist in the agriculture industry
for hydraulics?
Examples of hydraulics exist everywhere
in the world, and agriculture is no
exception when it comes to uses of
hydraulics.
From log splitters in your backyard to
gigantic machines we see on construction
sites, hydraulic equipment is amazing in
strength and agility.
What uses exist in the agriculture industry
for hydraulics?
 In construction zones, we see hydraulically
operated equipment in the form of bulldozers,
shovels, cranes, and forklifts.
 Another common piece of
equipment at construction
sites and agricultural
facilities is the skid/loader
using hydraulics to rotate
the bucket, lift the bucket,
and to raise and lower the
bucket.
What uses exist in the agriculture industry
for hydraulics?
 Large dump trucks usually have one cylinder or
two to lift the bed.
 These cylinders telescope, which gives them a
large range of motion for dumping loads, such as
rock or grain.
 Even the brakes in our
automobiles use
hydraulics.
Review/Summary
What are the basic components of a
hydraulic system and the role each
component plays in the system?
How is the efficiency for a hydraulic
system calculated?
What factors affect the efficiency of the
system?
Review/Summary
How is actual mechanical advantage and
ideal mechanical advantage calculated for
a hydraulic system?
What uses exist in the agriculture industry
for hydraulics?