HP PPT

2.  Introduction to fluid power
 Advantages of fluid power
 Application of fluid power system
 Types of fluid power systems,
 General types of fluids
◦ Properties of hydraulic fluids
◦ Fluid power symbols
 Basics of Hydraulics
◦ Applications of Pascal’s Law
◦ Laminar and Turbulent flow
◦ Reynolds’s number
◦ Darcy’s equation
◦ Losses in pipe, valves and fittings

3. FOLLOWING HISTORICAL FACTS:
 The fluid was used to generate power through
water wheels.
 The fluid was transmitted / pumped for irrigation
purpose by means of water wheels.
 The rivers were used as transportation means to
move from one place to another place using logs
of wood)
 The fluid was used to drive windmills. The
windmills were used to grind grains to pump
water.
 The fluid was used to propel the ships.
 The wooden valves were used to control water
flow through bamboo pipes

4.  Fluid is a substance which is capable of
flowing.
 Fluid power technology is deals with the
generation, control and transmission of power
using pressurized fluids.
 Fluid power is the general term. The fluid power
systems can be divided into (i).Hydraulic
systems, (ii).Pneumatic systems.
 Fluid power systems = hydraulic power systems +
pneumatic power systems
 The common methods of power transmission are
electrical, mechanical, and fluid power.

5. There are two different types fluid system:
 Fluid transport systems.
The objectives of fluid transport systems is to transport /
deliver fluid one place to another place for some useful
purpose.
Examples: Transport of water from water reservoir to
houses, industries using pipe lines.
 Fluid power systems.
The fluid power systems are primarily designed to perform
work. These systems are use pressurized fluids to
produce some useful mechanical movements to
accomplish the desired work.
Examples: The oil is used in various construction and
earth-moving equipments, hydraulic crane, presses,
hydraulic jacks.

6.  high horsepower-to-weight ratio
 safety in hazardous environments
 force or torque can be held constant
 high torque at low speed
 pressurized fluids can be transmitted over
long distances
 multi-functional control
 elimination of complicated mechanical
trains.
 motion can be almost instantly reversed

7.  Construction
 Mining
 Agriculture
 Waste Reduction
 Utility Equipment
 Marine
 Offshore
 Energy
 Metal Forming
 Machine Tools
 Military & Aerospace
 Other Applications

8. ELECTRICAL POWER TRANSMISSION.
 Electrical power is transmitted by
imposing an electromagnetic field on a
conductor.
 Suitability: They are suitable for power
transmission over long distances.
 Disadvantages: The limitations of
electrical power transmission include
magnetic saturation(limit torque
developed by an electric motor),
material limitations(affect the speed),
heat dissipation problem.

9. MECHANICAL POWER TRANSMISSION:
 Mechanical power is transmitted by
employing a variety of kinematic mechanism
likes belts, chains, pulleys, gear trains, bar
linkages, and cams.
 Suitability: They are suitable for the
transmission of motion and force over
relatively short distances.
 Disadvantages: Mechanical power
transmission include lubrication problems,
limited speed and torque control capacities,
uneven force distribution, and large space
requirements.

10. (a). Hydraulic power transmission:
 Hydraulic power is transmitted by the
pressure and flow of liquids. The most
common liquids used are petroleum oils.
 Suitability: They are suitable for power
transmission over intermediate distances.
 They can be employed over greater distances
than mechanical types.
 Advantages: Hydraulic systems are
mechanically stiff, and can be design to give
fast operation and move very heavy loads.
 Disadvantages: Hydraulic fluid leakage, fire
hazards with flammable hydraulic fluids.

11. (B). PNEUMATIC POWER TRANSMISSION:
 Pneumatic power is transmitted by the
pressure and flow of compressed gases. The
most commonly used gas is air.
 Suitability: They are suitable for power
transmission over intermediate distances.
 Advantages: Pneumatic systems used simple
equipment, have small transmission lines,
and do not present a fire hazard.
 Disadvantages: Pneumatic system include a
high air compressibility, small power-to-size
ratio of components.

13.  Move large loads by controlling high-
pressure fluid in distribution lines and
pistons with mechanical or
electromechanical valves1000psi – 3000psi
 Closed systems, always recirculating same
fluid

14.  Advantage:
– Able to generate extremely large forces from compact
actuators
– Easy to control speed
– Easy to implement linear motion
 Disadvantage:
– Large infrastructure (high-pressure pump, tank, distribution
lines)
– Potential fluid leaks
– Noisy operation
– Vibration
– Maintenance requirements, expensive
– Characteristics of working fluids change with temperature
and moisture

15. Pneumatic System Components
(storage tank)
(compressor/pump)

16. • Pneumatic systems similar to hydraulic systems
• Use compressed air as working fluid rather than hydraulic liquid
• 70psi - 150psi, much lower than hydraulic system pressures,
much lower forces than hydraulic actuators
• Energy can be stored in high pressure tanks
• Open systems, always processing new air

17. • Advantage:
– Constant force
– Clean (food industry)
– No return lines needed
– Adaptable infrastructure
– Possible light, mobile pneumatic systems
– Fast system response
• Disadvantage:
– Difficult to achieve position control (compressible
air)
– Noisy

18.  Density(mass density)
The density of a fluid is its mass per unit volume:
Liquids are essentially incompressible.
Density is highly variable in gases nearly proporti
onal to the pressure.
 Specific gravity(relative density)
Ratio of mass density of fluid to mass density of
standard fluid.
 Specific volume
Reciprocal of mass density

19.  Viscosity (µ)
 Viscosity is a measure of the fluid’s internal
resistance offered to flow.
 Unit is( Ns/m2)
 Absolute viscosity
Shear stress required to produce unit rate of shear
strain.
 Kinematic viscosity(ν)
Ratio of dynamic viscosity to mass density.
unit is m2/s.
 Cohesion
Intermolecular attraction between molecules of
same liquid
 Adhesion
◦ Attraction between molecules of liquid and molecules
of solid boundary in contact with liquid.

20.  Cavitation:
 Cloud of vapour bubble will form liquid pressure
drops below vapour pressure due to flow
phenomenon.
 Capillarity:
 Liquid rises into a thin glass tube above or below
its general level.
 Viscosity Index(VI):
 The rate of change of viscosity with temperature
is indicated in arbitrary scale.

21.  Compatibility
◦ Ability of hydraulic fluid to be compatible with
the system.
 Oxidation stability
 Oxidation is caused by a chemical reaction
between the oxygen of the dissolved air and the
oil.
 It creates impurities like sludge's, insoluble gum,
and soluble acidic products.
 Demusibility
 The ability of hydraulic fluid to separate from
moisture and successfully resist emulsification.
 The emulsion will promote the destruction of
lubricating value and sealant properties.

22.  Pour point:
◦ The temperature at which an oil will congeal is referred
to as the pour point
◦ i.e., the lowest temperature at which the oil is able to
flow easily.
 Flash point and Fire point:
◦ Flash point is the temperature at which a liquid gives
off vapour in sufficient quantity to ignite momentarily
or flash when flame is applied.
◦ The minimum temperature at which the hydraulic fluid
will catch fire and continue burning is called fire point.
 Neutralisation number:
◦ It is a measure of the acidity or alkalinity of the
hydraulic fluid.
◦ This is referred to as the pH value of the fluids
◦ High acidity causes the oxidation rate in an oil to
increase rapidly.

23.  Physical and Chemical stability to prevent
formation.
 Freedom from acidity ,so that fluid is non corrosive
to the metals in the systems.
 Lubricating properties sufficient to avoid wear.
 Pour point well below the minimum temperature.
 Flash point as high as possible.
 Minimum toxicity.
 Better fire resistance.
 Good oxidation stability.
 High bulk modulus and degree of incompressibility.

24. BASICS OF HYDRAULICS

25.  Hydraulic press

27.  Hydraulic jack

28.  Laminar
 Turbulent

35. The turbulent flow converted into laminar flow by reducing the velocity and
increasing diameter.

37. 

39.  Whenever a force acts on a body and the body
undergoes a displacement in the direction of the
force.
 Work done = Force x Distance moved (N-m)
(1 N-m = 1J)

40.  Power is the rate of doing work or work done per
unit time.
 Power = Work done / Time taken (N-m/s)
(1 Watt = 1 J/s = 1 N-m/s)

41.  Torque is the moment created by the force(F) at
the joint at the distance(d)
 Torque ,T = Force x distance (N-m)
 The amount of power transmitted by shaft can be
given by
P = 2πNT / 60

42.  Energy may be defined as the capacity to do work.
 The energy exists in many forms likes, potential
energy, pressure energy, kinetic energy, thermal
energy, etc.

43.  Sources of Hydraulic Power
◦ construction and working of pumps – Variable
displacement pumps
◦ Actuators: Linear hydraulic actuators
◦ Single acting and Double acting cylinders
◦ Fluid motors.
 Control Components:
 Direction control valve
 Flow control valves
 Electrical control -- solenoid valves. Relays,
Accumulators and Intensifiers.

44.  Hydraulic pumps can be classified using three
basic aspects:
 Displacement
 Pumping motion
 Fluid delivery characteristics

45.  Displacement relates to how the output of the
pump reacts to system loads
 Positive-displacement pumps produce a constant
output per cycle
 Non-positive-displacement pumps produce flow
variations due to internal slippage
 Positive Displacement Pump used where pressure
development is prime required.

46.  A non-positive-displacement pump has large
internal clearances
 Allows fluid slippage in the pump
 Results in varying flow output as system load
varies

47.  Non-positive-displacement pump

48.  Classification of Positive Displacement Pumps
 Gear pumps
 A)External B)Internal C)Lobe D)Screw
 Vane pumps
 A)Unbalanced B)Balanced
 Piston pumps
 A)Axial
 B)Radial

49.  Gear pumps are rotary pumps
Sauer-Danfoss, Ames, IA

50.  Piston pumps are reciprocating pumps
Reciprocating piston movement

51.  Hydraulic pumps are classified as either fixed
or variable delivery
 Fixed-delivery pumps have pumping chambers
with a volume that cannot be changed; the
output is the same during each cycle
 In variable-delivery designs, chamber geometry
may be changed to allow varying flow from the
pump

52.  In a rotary pump, the pumping action is produced
by revolving components
 In a reciprocating pump, the rotating motion of
the pump input shaft is changed to reciprocating
motion, which then produces the pumping action

53.  Gear pumps are fixed-delivery pumps

54.  Piston pumps may be designed as variable-
delivery pumps

55.  When selecting a pump for a circuit, factors that
must be considered are:
 System operating pressure
 Flow rate
 Cycle rate
 Expected length of service
 Environmental conditions
 Cost

56.  Gear pumps are positive-displacement, fixed-
delivery, rotary units
 Gear pumps are produced with either
external or internal gear teeth configurations

57.  Gear pumps are commonly used

58.  Pumping action of gear pumps results from
unmeshing and meshing of the gears
 As the gears unmesh in the inlet area, low
pressure causes fluid to enter the pump
 As the pump rotates, fluid is carried to the pump
discharge area
 When the gears mesh in the discharge area, fluid
is forced out of the pump into the system

59.  Gear pumps are available in a wide variety of
sizes
 Flow outputs from below 1 gpm to 150 gpm
 Pressure rating range up to 3000 psi

60.  Operation of a lobe pump

61.  The gerotor pump design is an internal-gear
pump
 Uses two rotating, gear-shaped elements that
form sealed chambers
 The chambers vary in volume as the elements
rotate
 Fluid comes into the chambers as they are
enlarging and is forced out as they decrease in
size

62.  The gerotor is a common internal-gear design

63.  Gerotor operation

64.  Gerotor operation

65.  Gerotor operation

66.  Gerotor operation

67.  A bent-axis axial-piston pump

68.  Vane pumps are positive-displacement, fixed
or variable delivery, rotary units.
 Design is commonly used in industrial
applications
 Delivery can range up to 75 gpm
 Maximum pressure of about 2000 psi

69.  Vane pump consists of a slotted rotor, fitted with
moveable vanes, that rotates within a cam ring
in the pump housing
 Rotor is off center in the ring, which creates pumping
chambers that vary in volume as the pump rotates
 As chamber volume increases, pressure decreases,
bringing fluid into the pump
 As volume decreases, fluid is forced out into the
system

70.  Operation of a typical vane pump

71.  Parts of a typical vane pump

72.  Vane pump may be pressure unbalanced or
pressure balanced
 Unbalanced has only one inlet and one discharge,
which places a side load on the shaft
 Balanced has two inlets and two discharges
opposite each other, creating a pressure balance
and, therefore, no load on the shaft

73.  Piston pumps are positive-displacement,
fixed- or variable-delivery, reciprocating
units
 Several variations
 Many provide high volumetric efficiency (90%),
high operating pressure (10,000 psi or higher),
and high-speed operation

74.  A basic piston pump consists of a housing
that supports a pumping mechanism and a
motion-converting mechanism
 Pumping mechanism is a block containing
cylinders fitted with pistons and valves
 Motion converter changes rotary to reciprocating
motion via cams, eccentric ring, swash plate, or
bent-axis designs
 Rotating the pump shaft causes piston movement
that pumps the fluid

75.  Piston pump classification is based on the
relationship between the axes of the power
input shaft and piston motion
 Axial
 Radial
 Reciprocating

76.  Axial piston pumps use two design variations:
 Inline
 Bent axis

77.  Inline has the cylinder block and pistons
located on the same axis as the pump input
shaft
 Pistons reciprocate against a swash plate
 Very popular design used in many applications

78.  An inline axial-piston pump

79.  Bent axis has the cylinder block and pistons set at
an angle to the input shaft
 Geometry of the axis angle creates piston movement
 Considered a more rugged pump than inline
 Manufactured in high flow rates and maximum operating
pressures

80.  Radial piston pumps have the highest
continuous operating pressure capability of
any of the pumps regularly used in hydraulic
systems
 Models are available with operating pressure
ratings in the 10,000 psi range

81.  Two variations of radial piston pumps:
 Stationary-cylinder design uses springs to hold pistons
against a cam that rotates with the main shaft of the
pump
 Rotating-cylinder design uses centrifugal force to
hold pistons against a reaction ring
 When the main shaft is rotated, each piston
reciprocates, causing fluid to move through the
pump

82.  A stationary-cylinder radial-piston pump

83.  Large, reciprocating-plunger pump designs
were widely used when factories had a
central hydraulic power source
 Today, plunger pumps are typically found in
special applications requiring high-pressure
performance

84.  Screw pumps have pumping elements that
consist of one, two, or three rotating screws
 As the screws rotate, fluid is trapped and
carried along to the discharge of the pump
 The design of screw pumps allows them to
operate at a very low noise level

85.  A typical screw pump

86.  The lobe pump is a close relative of the gear
pump
 Two three-lobed, gear-shaped units are often used
to form the pumping element
 Output flow is larger than a gear pump of
comparable physical size because of pumping
chamber geometry
 Lower pressure rating than gear pumps
 Tend to have a pulsating output flow

87.  Propeller and jet pumps are non-positive-
displacement pumps
 Sometimes used to transfer fluid within hydraulic
systems
 Propeller pump consists of a rotating propeller-
shaped pumping element
 Jet pump creates flow by pumping fluid through
a nozzle concentrically located within a venturi

88.  Check valve
 Pilot operated check valve
 Three-way and four-way valves
 Manually-actuated valve
 Pilot actuated valve
 Solenoid actuated valve
 Center flow path configuration
 Shuttle valve

96.  Pressure relief valve
 Compound pressure relief valve
 Pressure-reducing valve

100. Restrictor needle
valve

107.  Dampen pulsationsand shocks of a periodic nature
 Increase the speed of the operationalcircuit.
 Clamping devices to hold the jaw vices and fixtures
 Standby power supplycircuits.
 Surge reductioncircuits
 Agricultural Machinery & Equipment
 Forestry Equipment
 Oil Field & Offshore
 Machine Tools and Off- Road Equipment
Mining Machinery & Equipment
 Mobile & Construction Equipment
 Suspension invehicles

109.  Pneumatic Components:
 Properties of air. Compressors.
 FRL Unit –
 Air control valves,
 Quick exhaust valves
 pneumatic actuators- cylinders, air motors.

110.  Branch of engineering science which deals with
the study of the behaviour and application of
compressed air.
 It is abundantly available.
 It is safe to use.
 It is very cheaper
 Easier maintenance and easy handling.
 It can be exhausted easily.

111.  Density is lesser
 Viscosity is lesser
 Reduce the requirement of special designs
 Comparatively cheaper in cost
 Provide better operational
 Lesser in weight
 Leakage will not affect the system
performance

112.  Cannot provide precise actuator control and
precise positioning control
 It can be used for low pressure applications.
 Applications
 Stamping Materialhandling
 Drilling hammering
 Hoisting
 Punching
 Assembling
 Clamping
 Riveting

113.  Air is a mixture of gas
 Main constituents of air by volume are
 78% of nitrogen
 21% of oxygen
 1% of other gases (argon and carbondioxide)

116.  Positive displacement types
 Working on the principles of increasing the
pressure of a definite volume of air by reducing
that volume in an enclosed chamber
 Dynamic compressor or turbo compressor
 Employs rotating vanes or impellers to increase
the pressure of the air

117.  Fig shows single-acting piston actions in the cylinder of a
reciprocating compressor.
 The piston is driven by a crank shaft via a connecting rod.
 At the top of the cylinder are a suction valve and a discharge valve.
 A reciprocating compressor usually has two, three, four, or six
cylinders in it.

118.  Staging
 Dividing the total pressure among two or more
cylinders by allowing the outlet from one
cylinder into the inlet of the next cylinder and so
on.
 In single stage compressor gives the compressed
air of about 5 bar, the compressed air
temperature can rise over to 200⁰C.
 effective cooling of compressor is necessary.
 When used multistage compressor effective cooling
can be implemented between stages.
 Reduces input power requirements
 Increase the efficiency of the compressor.

119.  Pressure has been developed in the
compressor piping. The pressure will push
back against the compressor. This makes
starting the compressor more difficult when
required.
 Starting unloader valve is required to start
compressor whenever desired .This
arrangement releases the pressure in the
piping to the atmosphere and now the
compressor is free to start.

120.  Screw compressors are also belong to the positive
displacement compressor family.
 In screw compressors, the compression is
accomplished by the enmeshing of two mating
helically grooved rotors suitably housed in a
cylinder equipped with appropriated inlet and
discharge ports

121.  The rotor shaft is mounted eccentrically in a
steel cylinder so that the rotor nearly touches
the cylinder wall on one side, the two being
separated only by an oil film at this point.
 Directly opposite this point the clearance
between the rotor and the cylinder wall is
maximum.
 Heads or end-plates are installed on the ends
of the cylinder and to hold the rotor shaft.

122.  The vanes move back and forth radially in the rotor slots as
they follow the contour of the cylinder wall when the rotor is
turning.
 The vanes are held firmly against the cylinder wall by action
of the centrifugal force developed by the rotating rotor.
 In some instances, the blades are spring-loaded to obtain a
more positive seal against the cylinder wall.

123. Air In Air Out
Louver
Bowl
Filter
Element
Sight
Gauge
Drain Cock

124. Air In Air Out
Adjustable
Locking Knob
Main Spring
Diaphragm
Assembly
Valve Assembly Valve Spring

126.  Port 2 is connected directly
to the end cover of a
cylinder
 Port 1 receives air from the
control valve
 Air flows past the lips of the
seal to drive the cylinder
 When the control valve is
exhausted, the seal flips to
the right opening the large
direct flow path
 Air is exhausted very rapidly
from the cylinder for
increased speed
1
2
1
2
1
2

127.  Fluidics – Introduction to fluidic devices,
simple circuits Introduction to Electro
Hydraulic Pneumatic logic circuits, PLC
applications in fluid power control, ladder
diagrams
 Fluid Power Circuit Design: Sequential circuit
design for simple applications using classic,
cascade, step counter, logic with Karnaugh-
Veitch Mapping and combinational circuit
design methods.

137.  Speed control circuits, synchronizing circuit,
Pneumo hydraulic circuit, Accumulator
circuits, Intensifier circuits. Servo systems –
Hydro Mechanical servo systems, Electro
hydraulic servo systems and proportional
valves.
 Deceleration circuit, hydrostatics
transmission circuits, control circuits for
reciprocating drives in machine tools, Material
handling equipments. Fluid power circuits;
failure and troubleshooting.