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Fluid Power Systems Overview

Fluid power systems use liquids or gases under pressure to generate, control, and transmit power. Hydraulics uses liquids while pneumatics uses gases. Hydraulic systems can produce high power and forces in small volumes using pumps, motors, cylinders, valves, and tanks. An ideal hydraulic fluid is thermally stable, resistant to chemicals and corrosion, has a long life, and is inexpensive. Common hydraulic fluids include mineral oils, water-based fluids, and phosphate esters. Hydraulic components include reservoirs, pumps, motors, cylinders, and various control valves.

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160 views8 pages

Fluid Power Systems Overview

Fluid power systems use liquids or gases under pressure to generate, control, and transmit power. Hydraulics uses liquids while pneumatics uses gases. Hydraulic systems can produce high power and forces in small volumes using pumps, motors, cylinders, valves, and tanks. An ideal hydraulic fluid is thermally stable, resistant to chemicals and corrosion, has a long life, and is inexpensive. Common hydraulic fluids include mineral oils, water-based fluids, and phosphate esters. Hydraulic components include reservoirs, pumps, motors, cylinders, and various control valves.

Uploaded by

Nathan DM
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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HYDRAULICS

AND
PNEUMATICS

Introduction to Fluid Power and Fluid Power Systems


WHAT IS FLUID POWER?

Ø Fluid power is the use of fluids under pressure to generate, control, and transmit
power.

Ø They are subdivided into hydraulics and Pneumatics. Hydraulics deals with the study
of liquids and pneumatics studies air and other gasses.

Ø Fluid Power Systems can produce high power and high forces in small volumes.

Ø Fluid Power System has a pump driven by a prime mover that converts mechanical
energy to fluid energy.
PROPERTIES OF HYDRAULIC FLUIDS

• An ideal hydraulic fluids will have the following properties.


1. Thermal stability.
2. Hydrolytic stability.
3. Low chemical corrosiveness.
4. Long life.
5. Low cost.
6. Low tendency to cavitate.
TYPES OF HYDRAULIC FLUIDS
Hydraulic Fluids are classified into the following categories
Ø Mineral oils : They are obtained from refining of crude oils.
Ø Fire Resistant Fluids : Its an oil in water emulsion. HFAB , HRAS, HFC, HFDR and HFDS
are the different types of fire resistant fluids.
Ø Water/ oil Emulsions: Predominant (around 60% ) of oil is mixed with water.
Ø Water glycol : Known as HFC, its 40% water mixed with 60% glycol.
Ø Phosphate Esters : Known as HFDR, resistant to fire and will not ignite up to
temperatures 550 Celsius.
HYDRAULICS
Hydraulic machines are machinery and tools that use liquid power to do
work. In heavy equipment hydraulic fluid is transmitted throughout the
machine by various hydraulic motors and hydraulic cylinders. Hydraulics
follow Pascal’s law.

Hydraulic Circuits:

Ø Open loop circuits : It uses pumps which supply a continuous flow. The
flow is returned to tank through the control valve’s open center, it provides
an open return path to tank and the fluid is not pumped to a high pressure.

Ø Closed loop circuits: It supplies full pressure to the control valves,


Whether any valves are actuated or not. The pumps vary their flow rate,
Pumping very little hydraulic fluid until the operator actuates a valve.
The valve’s spool therefore doesn’t need an open center return path to tank.
STRUCTURE OF HYDRAULIC SYSTEM
STRUCTURE OF HYDRAULIC SYSTEM

The following are the components forms the basic of a hydraulic system.
1. Reservoir/ Tank : Used to store the hydraulic fluid.
2. Hydraulic Pump : Used to pressurize the fluid and force the fluid through the system.
3. Hydraulic Motor : Converts hydraulic pressure to torque or angular displacement.
4. Hydraulic Cylinder : Mechanical actuator converts hydraulic energy to linear displacement.
5. Pressure Control Valve : Limits the system pressure to protect the system.
6. Flow Control Valve : Adjusts the flow rate of the liquid in the line
7. Directional Control Valve : Controls the directional flow of the fluid
8. Proportional Valve : Varies flow rate or reduces the pressure
9. Cheque Q Meter : Controls the returning flow in relation to the flow being directed in to opposite side
of actuator
10. Solenoid Valve : Its function is to shut off or distribute and release fluid.
ADVANTAGES AND APPLICATIONS OF FLUID POWER SYSTEMS

• Advantages: Applications :
1. Multiplication of force 1. Truck brakes
2. Easy and accurate control 2. Suspensions
3. Earth movers
3. Multi Function Control 4. Metalworking equipment
4. Low Speed Torque 5. Assembly Equipment
6. Landing gear
5. Constant Force or Torque
7. Flight Controls
8. Cargo Loading Equipment

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