UNIT I - FLUID POWER PRINCIPLES AND FUNDEMENTALS (REVIEW) CLASS NOTES

1. ME6021 –
Hydraulics &
Pneumatics
Unit 1 - Fluid Power
Principles and
Fundamentals (Review)
Kinathukadavu, Coimbatore.
Prepared By:
Santhosh Kumar.B, M.E.,
Asst.Prof/Dept. of Mech. Engg.

2. Syllabus
UNIT I - FLUID POWER PRINCIPLES AND FUNDEMENTALS (REVIEW)
Introduction to Fluid power- Advantages and Applications- Fluid power
systems - Types of fluids - Properties of fluids Basics of Hydraulics - Pascal’s Law-
Principles of flow - Work, Power and Torque - Properties of air - Perfect Gas
Laws.
Hours Required : 03
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

3. Introduction to Fluid Power.
All machines require some type of power source and a way of transmitting this
power to the point of operation.
The three methods of transmitting power are:
– Mechanical
– Electrical
– Fluid
In this course we are going to deal with the third type of power transmission which
is the Fluid Power.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

4. Introduction to Fluid Power. (Contd…)
– Fluid power is the method of using pressurized fluid to transmit energy.
– Fluid power is the technology that deals with the generation, control, and
transmission of power, using pressurized fluids.
– Liquid or Gas is referred to as a fluid. Accordingly, there are two branches of
fluid power; Pneumatics, and Hydraulics.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

5. History of Fluid Power.
– Ancient historical accounts show that water was used for centuries to produce
power by means of water wheels, and air was used to turn windmills and propel
ships.
– Pascal’s law [1647–48] and Bernoulli’s law [1738] operate at the very heart of all
fluid power.
– In 1906 when a hydraulic system was developed to replace electrical systems for
elevating and controlling guns on the battleship USS Virginia.
– In 1926 the United States developed the first unitized, packaged hydraulic
system consisting of a pump, controls, and actuator.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

6. Fluid Systems.
– Fluid transport systems
Fluid transport systems have as their sole objective the delivery of a fluid
from one location to another to accomplish some useful purpose
Example: pumping stations for pumping water to homes.
– Fluid power systems
Fluid power systems are designed specifically to perform work.
Example: Operating fluid cylinder or fluid motor.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

7. Types of Fluids.
– Hydraulic systems. (High Power Applications)
– Water Based (Water and Water Solutions)
– Oil Based (Petroleum oils and synthetic oils)
– Pneumatic Systems. (Low Power Applications)
– Air as the Gas medium.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

8. Introduction to Hydraulics.
– What is Hydraulic (from the Greek words hydra for water and aulos for a pipe)?
Hydraulics is the discipline that deals with the mechanical properties of
liquids, and applies the principles to solve engineering problems.
– Hydraulic systems are commonly used where mechanisms require large forces
and precise control.
– Examples include vehicle power steering and brakes, hydraulic jacks and heavy
earth moving machines.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

9. Basic Hydraulic System
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

10. Introduction to Pneumatics.
– What is Pneumatic (from the Greek pneumn for wind or breath).?
Pneumatics is the discipline that deals with mechanical properties of
gases such as pressure and density, and applies the principles to use
compressed gas as a source of power to solve Engineering problems.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

11. Basic Pneumatic System
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

12. Examples:
Mobile: Here fluid power is used to transport, excavate and lift materials as well as
control or power mobile equipment. End use industries include construction,
agriculture, marine and the military. Applications include backhoes, graders,
tractors, truck brakes and suspensions, spreaders and highway maintenance
vehicles.
Industrial: Here fluid power is used to provide power transmission and motion control
for the machines of industry. End use industries range from plastics working to
paper production. Applications include metalworking equipment, controllers,
automated manipulators, material handling and assembly equipment.
Aerospace: Fluid power is used for both commercial and military aircraft, spacecraft
and related support equipment. Applications include landing gear, brakes, flight
controls, motor controls and cargo loading equipment.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.
FlapsLanding gears

13. – Fluid power systems provide many benefits to users including:
– Multiplication and variation of force
– Easy, accurate control
– Multi-function control
– High horsepower, low weight ratio
– Low speed torque
– Constant force or torque-This is a unique fluid power attribute.
– Safety in hazardous environments
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.
Advantages of Fluid Power.

14. Disadvantages of Fluid Power.
– A hydraulic element needs to be machined to a high degree of precision.
– Leakage of hydraulic oil poses a problem to hydraulic operators.
– Special treatment is needed to protect them from rust, corrosion, dirt etc.,
– Hydraulic oil may pose problems if it disintegrates due to aging and chemical
deterioration.
– Hydraulic oils are messy and almost highly flammable.
– Hydraulic systems contain highly pressurized fluid. This can cause burns, bruises
or the accidental injection of fluid into the body.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

15. Fluids Properties.
– Viscosity:
It is a measured of the sluggishness with which a fluid moves. When the
viscosity is low, the fluid flows easily because it is thin and has low body.
– Viscosity Index:
A low V.I. signifies a relatively large change of viscosity with changes
of temperature. In other words, the oil becomes extremely thin at high
temperatures and extremely thick at low temperatures. On the other hand, a
high V.I. signifies relatively little change in
viscosity over a wide temperature range.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

16. Fluids Properties. (Contd…)
Other important Properties
1. Oxidation. 2. Flash point.
3. Fire point. 4. Corrosion.
5. Demulsibility. 6. Flammability.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

17. Pascal’s Law
Pascal's law (also Pascal's principle or the principle of
transmission of fluid-pressure) is a principle in fluid mechanics that states that a
pressure change occurring anywhere in a confined incompressible fluid is
transmitted throughout the fluid such that the same change occurs everywhere.
A change in pressure at any point in an enclosed fluid at rest is
transmitted undiminished to all points in the fluid.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

18. Principles of Flow.
– Energy:
The ability to do work
– Energy Transfer:
From prime mover, or input source, to an actuator, or output device
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

19. Principles of Flow. (Contd…)
– Work:
Force multiplied by distance - Measured in foot-pounds.
– Power:
The rate of doing work.
Work over time in seconds.
– Torque:
Twisting force x distance - Measured in foot-pounds.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

20. Properties of Air.
– Air has weight.
– Air is under pressure.
– Air has temperature.
– Air has a volume.
– Air usually contains some water vapour.
– Air usually has some velocity (speed).
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

21. Perfect Gas Laws.
The gas laws were developed at the end of the 18th century, when
scientists began to realize that relationships between the pressure, volume and
temperature of a sample of gas could be obtained which would hold to a good
approximation for all gases.
Gases behave in a similar way over a wide variety of conditions because
they all have molecules which are widely spaced, and the equation of state for
an ideal gas is derived from kinetic theory.
The earlier gas laws are now considered as special cases of the ideal gas
equation, with one or more of the variables held constant.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

22. Perfect Gas Laws.(Contd…)
Boyle's Law
At constant temperature, the product of the pressure and volume of a
given mass of an ideal gas in a closed system is always constant. It can be
verified experimentally using a pressure gauge and a variable volume container.
Charles's law
It states that, for a given mass of an ideal gas at constant pressure, the
volume is directly proportional to its absolute temperature, assuming in a
closed system.
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

23. Perfect Gas Laws.(Contd…)
Gay-Lussac's law:
Gay-Lussac's law, Amontons' law or the pressure law was found by Joseph
Louis Gay-Lussac in 1809. It states that, for a given mass and constant volume
of an ideal gas, the pressure exerted on the sides of its container is directly
proportional to its absolute temperature.
Combined and Ideal Gas Laws:
The Combined Gas Law or General Gas Equation is obtained by combining
Boyle's Law, Charles' Law, and Gay-Lussac's Law. It shows the relationship
between the pressure, volume, and temperature for a fixed mass (quantity) of
gas:
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.

24. Thank You…
19-Jul-17B.Santhosh Kumar, M.E., - A.P/Mech - Sri Eshwar College of Engg. - CBE.