Introduction, Global fluid power Scenario, Basic system of Hydraulics-Major advantages and disadvantages, Principles of Hydraulic Fluid power, Hydraulic Symbols, Electrical Elements used in hydraulic circuits.

1. CHAPTER 1
INTRODUCTION
13 August 2020 1
Prepared by : Prof. Rahul Thaker
Department of Mechanical Engineering
Alpha College of Engineering & Technology

2. Contents
Introduction
Classification of Fluid Power Systems
Hydrostatic and Hydrodynamic Systems
Advantages of a Fluid Power System
Basic Components of a Hydraulic System
Basic Components of a Pneumatic System
Comparison Between Hydraulic And Pneumatic
Systems
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3. INTRODUCTION
 Fluid power system includes a hydraulic system and a
pneumatic system.
 hydra meaning “water” in Greek
 pneuma meaning “air” in Greek
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4. hydraulic systems type:
Fluid transport systems:
delivery of a fluid from one location to another to
accomplish some useful purpose
Examples include pumping stations for pumping water
to homes, cross-country gas lines, etc.
Fluid power systems:
Work is obtained by pressurized fluid acting directly
on a fluid cylinder or a fluid motor.
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5. INTRODUCTION
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6. INTRODUCTION
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7. Classification of Fluid Power Systems :
Based on the control system
 Open-loop system
 Closed-loop system
Based on the type of control
 Fluid logic control
o This type of system is controlled by hydraulic oil or air. The
system employs fluid logic devices such as AND, NAND, OR,
NOR, etc.
 Electrical control
 Electronic control
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8. INTRODUCTION
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9. Hydrostatic and Hydrodynamic Systems
Hydrostatic system uses fluid pressure to
transmit power.
Hydrostatics deals with the mechanics of still
fluids and uses the theory of equilibrium
conditions in fluid.
Example: transfer of force in hydraulics.
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10. Hydrostatic and Hydrodynamic Systems
Hydrodynamic systems use fluid motion to
transmit power.
Power is transmitted by the kinetic energy of
the fluid.
Hydrodynamics deals with the mechanics of
moving fluid.
Example: conversion of flow energy in turbines
in hydroelectric power plants .
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11. INTRODUCTION
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12. INTRODUCTION
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13. Advantages of a Fluid Power System
 Fluid power systems are simple, easy to operate and can be
controlled accurately
 Multiplication and variation of forces
 Multifunction control:
 Low-speed torque
 Constant force or torque
 Economical
 Low weight to power ratio
 Fluid power systems can be used where safety is of vital
importance
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14. ADVANTAGES OF HYDROSTATIC
DRIVES
 Simple method to create linear movements
 Creation of large forces and torques, high energy density
 Continuously variable movement of the actuator
 Simple turnaround of the direction of the movement, starting
possible under full load from rest
 Low delay, small time constant because of low inertia
 Simple overload protection (no damage in case of overload)
 Simple monitoring of load by measuring pressure
 Arbitrary positioning of prime mover and actuator
 Large power density (relatively small mass for a given power
 compared to electrical and mechanical drives)
 Robust (insensitive against environmental influences) 14

15. DISADVANTAGES OF HYDROSTATIC
DRIVES
 Working fluid is necessary (leakage problems, filtering,
etc.)
 It is not economic for large distances
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16. Basic Components of a Hydraulic
System
16Figure 1. Components of a hydraulic system13 August 2020
 Hydraulic systems are power-transmitting assemblies employing
pressurized liquid as a fluid for transmitting energy from an energy-
generating source to an energy-using point to accomplish useful work.

17. hydraulic actuator: To convert the fluid power into
mechanical power to do useful work.
hydraulic pump: To force the fluid from the reservoir to
rest of the hydraulic circuit by converting mechanical
energy into hydraulic energy.
Valves: To control the direction, pressure and flow rate of
a fluid flowing through the circuit
External power supply (motor) :to drive the pump.
Reservoir: To hold the hydraulic liquid.
Filters: To remove any foreign particles so as keep the
fluid system clean and efficient, as well as avoid damage
to the actuator and valves.
Pressure regulator: regulates the required level of
pressure in the hydraulic fluid
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18. 18Figure 2. Components of a hydraulic system (shown using symbols)13 August 2020 @RT

19.  When the electric motor is switched ON, it runs a
positive displacement pump that draws hydraulic
oil through a filter and delivers at high pressure.
 The pressurized oil passes through the regulating
valve and does work on actuator. Oil from the
other end of the actuator goes back to the tank via
return line.
 To and fro motion of the cylinder is controlled
using directional control valve.
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21. Basic Components of a Pneumatic
System
21
Figure 3 Components of a pneumatic system
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22. Pneumatic actuator: converts the fluid power into
mechanical power to perform useful work.
Compressor: To compress the fresh air drawn from the
atmosphere.
Storage reservoir: To store a given volume of compressed
air.
Valves: To control the direction, flow rate and pressure of
compressed air.
External power supply (motor): To drive the
compressor.
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23. 2313 August 2020 @RT
Comparison Between Hydraulic And Pneumatic Systems

24. 2413 August 2020 @RT
Comparison Between Hydraulic And Pneumatic Systems

25. 2513 August 2020 @RT

26. ADVANTAGES AND
DISADVANTAGES Advantages:
very flexible , free-format syntax.
Supported by every product.
It can express arithmetic operations as well
as operations to aggregate data and sort data for
output.
 Disadvantages:
It is not a general-purpose programming
language and thus the development of an
application requires the use of a SQL with a
programming language.