5. Pressure applied to piston “A” is
transferred equally to a piston of the same
size “B” because PSI is the same
throughout the system.
Basic
principle
6. Pascal’s Law
Pressure applied to a
confined fluid is:
transmitted undiminished in
all directions,
acts with equal force on equal
areas, and
acts at a right angle to the
walls of the container.
10 psi
10-lb
1 in2
Area = 10 in2
Force = 100-lbs.
7. Important Properties:
“Shapelessness”
Liquids have no neutral form
Conform to shape of container
Easily transferred through piping from one location
to another
Incompressibility
Liquids are essentially incompressible
Once force is removed, liquid returns to original
volume (no permanent distortion)
Transmission of Force
Force is transmitted equally & undiminished
in every direction -> vessel filled with pressure
9. Hydraulic circuit:
A hydraulic circuit is a system comprising
an interconnected set of discrete
components that transport liquid.
10. Pump
Functions in a hydraulic
system by pressurizing
and moving fluid from one
part of the system to
another.
11. Hydraulic pumps are usually of three
types:
1. GEAR PUMP
2. PISTON PUMP
3. VANE PUMP
12. Gear Pumps:
Fixed or constant displacement pump.
Work well at 1500 psi and below
Work with a minimum of moving parts
Less expensive to manufacture than piston
type pumps
14. Piston Pumps
Work well at 2000 psi or more.
Require several pistons working together to
generate enough volume for tractor
applications
Necessarily involve many moving parts
Two types-1.Axial piston pump
2.Radial piston pump
15. Vane pump
Also works at 1500 psi and below
Three types-1.sliding vane
2.swinging vane 3.Rolling vane
16. Hydraulic Cylinders:
The main function of a cylinder is to convert hydraulic
power into linear mechanical force.
This force performs work or transmits power.
Types : 1.Ram cylinder
2.Single Acting
3.Telescopic
4.Spring Return
5.Double Acting
17. Ram Cylinders:
The simplest single acting cylinder
One fluid chamber
Exerts force in only one direction
Mounted mostly vertically
The cylinder retracts by the force of the load
due to gravity
Ram cylinders are most commonly used in
elevators, jacks, and automobile hoists.
18. Single Acting Cylinders:
Acts much like a ram cylinder
Main difference is that the single acting cylinder uses a
piston. The leakage flow that goes past the piston is
ported the tank.
Telescopic Cylinders:
• Mostly a single acting cylinder
• Series of rod segments called sleeves, most common to only
have 4 or 5 sleeves in each cylinder
• The sleeves work together to provide a longer stroke
• The maximum force is at the collapsed position
• The speed will increase at each stage, but will not allow as
much force.
19. Spring Return Cylinders:
Considered a single acting cylinder
Pressure applied to the cap end pushes the spring down as
the rod is extending
When the pressure is removed the spring force allows the
cylinder to retract
The drain is in the spring chamber and allows the leakage
flow past the piston seal
20. Double Acting Cylinders:
Types:-1.Double acting (differential cylinder)
2.Double rod cylinder (nondifferential cylinder)
3.Tendom
Pressure is applied to both rod end and cap end
Rod extension is slower because has a larger area,
but allows a greater force because of the bigger
area.
Retract is faster because of the smaller area, but
the force allowed is smaller because of the smaller
area.
21. Double Acting Cylinders:
Tandem Cylinder-
Two pistons in line with a common rod
This allows you to have a greater forces without
increasing the size of the cylinder bore
Tandem cylinders are used in places where
there is insufficient space to increase the size of
the cylinder bore.
22. Control valves:
Functions of a valve:-
1.direct the flow of fluid
2.regulate the pressure
3.control volume
Three types of valves:
Pressure – adjust psi for some purpose
Directional -- route the fluid to the desired actuator
Volume Control or Flow Control -- control the
amount of flow
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Fluid Properties:
These properties include:
Viscosity and Viscosity Index
Pour Point
Specific gravity
Thermal properties- specific heat & thermal
conductivity
Lubricating Ability
Rust and corrosion protection
Fire resistance