Important project report 1

AUTOMOBILE DEPARTMENT BOARD MOUNTED HYDRAULIC DEVICES
1P. V.P. I.T. BUDHGAON
ACKNOWLEDGEMENT
We are rather infused by Prof. S.S .mane Sir who put us in cradle of
engineering studies & evaluated us to this end & mean of our project
report without his guidance, we are sure to be orphan in vast ocean of
subject. Ultimately no tongue could describe deep sense of co-operation
and ready nature to help us even in our minute details of the write up of
the project report.
We would like to thank Prof. S. Y. Saptasagar Head of automobile
department for his valuable guidance & encouragement.
Further we are thankful to all teaching and non teaching staff of
AUTOMOBILE DEPARTMENT for their co-operation during
seminar report work. We are very grateful to those who in the form of
books and conveyed guidance in this project report work.
Finally we thank our colleagues, friends and all other who helped us
directly or indirectly.
Sr. No. Name Roll No.
1 Mr. Patil Sukhdev Govind 02
2 Mr. Shelar Shubham Vijay 04
3 Mr. Sutar Aditya Ashok 05
4 Mr. Swami Pavan Sadashiv 06

Sr. No. Index Page No.
1 List of Figure 5
2 Introduction 8
3 Hydraulic Pump 9
3.1 Gear pump- 10
External gear pump 11
Internal Gear pump 14
3.2 Vane pump 17
3.3 Lobe Pump 19
3.4 Screw Pump 22
3.5 Piston Pump 25
4 Control Components 29
4.1 Direction Control valve- 30
Poppet Valve 31
Sliding-Spool Valve 33
Two-Way Valve 34
Three-Way Valve 35
Four-Way Valves 37
4.2 Pressure Control Valve- 45
Pressure Relief Valve 45
Direct Type Relief Valve 46
Unloading Valve 47
Sequence Valve 48

Counterbalance Valve 49
Pressure reducing valve 50
4.3 Flow control valve- 51
Gate Valve 52
Plug or glove valve 53
Butterfly valve 54
Ball Valve 55
Balance valve 56
5 Actuator 57
5.1 Cylinder- 57
Single Acting 57
Double Acting 57
Differential Cylinder 58
Piston Type Cylinder 58
Cushioned Cylinder 60
Lockout Cylinder 61
5.2 Hydraulic Motor- 62
Gear type motor 63
Vane type motor 64
6 Fitting & connector 66
Threaded Connector 66
Flared connector 67
Flexible hose coupling 70

Reusable Coupling 71
7 Cutting Procedure 72
Vane Pump 72
Gear pump 73
Double acting cylinder 74
Single acting cylinder 74
Flow control valve 75
Hoses 75
8 Tools & Equipment 76
9 Costing 78
10 Conclusion 79
11 References 80

List of figure
Sr. No. Name Page No.
Fig 3.1 Gears of pump 09
Fig 3.2 An exploded view of an external gear pump 11
Fig 3.3 Working of external gear pump 12
Fig 3.4 An exploded view of an internal gear (Gerotor) pump 14
Fig 3.5 Internal gear (Gerotor) pump 14
Fig 3.6 Working of Internal gear pump 15
Fig 3.7 Workingof Vane Pumps 17
Fig 3.8 Workingof lobe Pumps 20
Fig 3.9 Screw pump 22
Fig 3.10 Piston Pump 25
Fig 4.1 2 / 2 DCV Poppet Design 32
Fig 4.2 Symbol of 2/2 poppet valve ( Check valve ) 32
Fig 4.3 Spool type 2 / 2 DCV 34
Fig 4.4 4.9 2 /3 DCV 36
Fig 4.5 Two- position, four – way DCV 31
Fig 4.6 2 / 4 DCV with manually operated 39
Fig 4.7 2 / 4 DCV with manually operated by hand lever 39
Fig 4.8 Working of solenoid to shift spool of valve 40
Fig 4.9 Pilot actuated DCV 42
Fig 4.10 Symbol for Pneumatic actuated 2 / 4 DCV 43

Fig 4.11 Pressure Relief Valve 46
Fig 4.12 Unloading Valve 47
Fig 4.13 Sequence valve 48
Fig 4.14 Counter Balance Valve 49
Fig 4.15 Pressure Reducing Valve 50
Fig 4.16 Gate valve 52
Fig 4.17 Plug or glove valve 53
Fig 4.18 Butterfly valve 54
Fig 4.19 Ball valve 55
Fig 4.20 Balanced valves 56
Fig 5.1 Piston Type cylinder 58
Fig 5.2 Double-acting, piston-type cylinder 59
Fig 5.3 Cushioned, actuating cylinder 60
Fig 5.4 Basic operations of a hydraulic motor 62
Fig 5.5 Gear-type motor 63
Fig 5.6 Vane-type motor 64
Fig 5.7 Pressure differential on a vane-type motor 64
Fig 5.8 Rocker arms pushing vanes in a pump 65
Fig 6.1 Threaded-pipe connectors 66
Fig 6.2 Flared tube connector 67
Fig 6.3 Flared tube Fittings 69
Fig 6.4 Field-attachable couplings 70
Fig 6.5 permanently attached couplings 71

Fig 7.1 Cutting & grinding of vane pump 72
Fig 7.12 Dismantling & cutting of gear pump 73
Fig 7.3 cutting of flow control valve 75

2) INTRODUCTION
Hydraulic machinery is very essential in industries for improving quality of parts &
reduces the time of manufacturing of new parts. Hydraulic machine are used in
industries, & it can be hydrostatic or Hydrodynamic.
Hydraulic pump is a mechanical source of Pollster that converts mechanical power
into Hydraulic energy, (Hydrostatic energy i.e. flow, pressure). It generates Row of
with rough power to overcome pressure inducted by the load at the pump outlet.
When a Hydraulic pump operates its creates a vacuum at the pump inlet, which
forces liquid from the reservoir into the inlet line to the pump & by mechanical
action delivers this liquid to the pump outlet & forces it into the Hydraulic systems.
Hydrostatic pumps are positive displacement pumps which Hydrodynamic pumps
can be fixed displacement in which the displacement (How thought the pumps per
rotation of the pump) cannot be adjusted or variable displacement pumps, which have
a more complicated construction that allows the displacement to be adjusted.
Although, Hydrodynamic pumps are more frequent in day to day life. Hydrostatics
pumps which are of various types of work on the principle of Pascal’s low. It states
that the increases in pressure in pressure at one point of the enclosed liquid in
equilibrium of rest are transmitted equally, to all other points of the liquid, unless the
effect of gravity is neglected.

3. Hydraulic pump
Hydraulic pumps are used in hydraulic drive systems and can be hydrostatic or
hydrodynamic. A hydraulic pump is a mechanical source of power that converts
mechanical power into hydraulic energy (hydrostatic energy i.e. flow, pressure). It
generates flow with enough power to overcome pressure induced by the load at the
pump outlet. When a hydraulic pump operates, it creates a vacuum at the pump inlet,
which forces liquid from the reservoir into the inlet line to the pump and by
mechanical action delivers this liquid to the pump outlet and forces it into the
hydraulic system. Hydrostatic pumps are positive displacement pumps while
hydrodynamic pumps can be fixed displacement pumps, in which the displacement
(flow through the pump per rotation of the pump) cannot be adjusted or variable
displacement pumps, which have a more complicated construction that allows the
displacement to be adjusted. Although, hydrodynamic pumps are more frequent in
day to day life. Hydrostatics pump which are of various types works on the principle
of Pascal’s law. It states that the increase in pressure at one point of the enclosed
liquid in equilibrium of rest is transmitted equally to all other points of the liquid,
unless the effect of gravity is neglected.(in case of statics)
Fig. 3.1 Gears of pump

Hydraulic pump types
3.1 Gear pumps:-
Gear pumps (with external teeth) (fixed displacement) are simple and
economical pumps. The swept volume or displacement of gear pumps for hydraulics
will be between about 1 and 200 milliliters. They have the lowest volumetric
efficiency (nv= 90%) of all three basic pump types (gear, vane and piston
pumps).These pumps create pressure through the meshing of the gear teeth, which
forces fluid around the gears to pressurize the outlet side. For lubrication, the gear
pump uses a small amount of oil from the pressurized side of the gears, bleeds this
through the (typically) hydrodynamic bearings, and vents the same oil either to the
low pressure side of the gears, or through a dedicated drain port on the pump
housing. Some gear pumps can be quite noisy, compared to other types, but modern
gear pumps are highly reliable and much quieter than older models. This is in part
due to designs incorporating split gears, helical gear teeth and higher precision or
quality tooth profiles that mesh and unmesh more smoothly, reducing pressure ripple
and related detrimental problems. Another positive attribute of the gear pump, is that
catastrophic breakdown is a lot less common than in most other types of hydraulic
pumps. This is because the gears gradually wear down the housing and/or main
bushings, reducing the volumetric efficiency of the pump gradually until it is all but
useless. This often happens long before wear causes the unit to seize or break down.

1) External gearpump
Fig 3.2 An exploded view of an external gear pump
External gear pumps are a popular pumping principle and are often used as
lubrication pumps in machine tools, in fluid power transfer units, and as oil pumps in
engines.
External gear pumps can come in single or double (two sets of gears)
pump configurations with spur (shown), helical, and herringbone gears. Helical and
herringbone gears typically offer a smoother flow than spur gears, although all gear
types are relatively smooth. Large-capacity external gear pumps typically use
helical or herringbone gears. Small external gear pumps usually operate at 1750 or
3450 rpm and larger models operate at speeds up to 640 rpm. External gear pumps
have close tolerances and shaft support on both sides of the gears. This allows them
to run to pressures beyond 3,000 PSI / 200 BAR, making them well suited for use in
hydraulics. With four bearings in the liquid and tight tolerances, they are not well
suited to handling abrasive or extreme high temperature applications.
Tighter internal clearances provide for a more reliable measure of
liquid passing through a pump and for greater flow control. Because of this, external
gear pumps are popular for precise transfer and metering applications involving
polymers, fuels, and chemical additives.

Working of External GearPumps
External gear pumps are similar in pumping action to internal gear pumps in that two
gears come into and out of mesh to produce flow. However, the external gear pump
uses two identical gears rotating against each other -- one gear is driven by a motor
and it in turn drives the other gear. Each gear is supported by a shaft with bearings
on both sides of the gear.
1. As the gears come out of mesh, they create expanding volume on the inlet side of
the pump. Liquid flows into the cavity and is trapped by the gear teeth as they rotate.
2. Liquid travels around the interior of the casing in the pockets between the teeth
and the casing -- it does not pass between the gears.
3. Finally, the meshing of the gears forces liquid through the outlet port under
pressure.
Because the gears are supported on both sides, external gear pumps are quiet-
running and are routinely used for high-pressure applications such as hydraulic
applications. With no overhung bearing loads, the rotor shaft can't deflect and cause
premature wear.
Fig 3.3 Working of external gear pump

Advantages
 High speed
 High pressure
 No overhung bearing loads
 Relatively quiet operation
 Design accommodates wide variety of materials
Disadvantages
 Four bushings in liquid area
 No solids allowed
 Fixed End Clearances
Materials of Construction/ Configuration Options
As the following list indicates, rotary pumps can be constructed in a
wide variety of materials. By precisely matching the materials of construction with
the liquid, superior life cycle performance will result.
External gear pumps in particular can be
engineered to handle even the most aggressive corrosive liquids. While external
gear pumps are commonly found in cast iron, newer materials are allowing these
pumps to handle liquids such as sulfuric acid, sodium hypochlorite, ferric chloride,
sodium hydroxide, and hundreds of other corrosive liquids.
 Externals (head, casing, bracket) - Iron, ductile iron, steel, stainless steel,
high alloys, composites (PPS, ETFE)
 Internals (shafts) - Steel, stainless steel, high alloys, alumina ceramic
 Internals (gears) - Steel, stainless steel, PTFE, composite (PPS)
 Bushing - Carbon, bronze, silicon carbide, needle bearings
 Shaft Seal - Packing, lip seal, component mechanical seal, magnetically-
driven pump

2) Internal gearpump
Fig. 3.4 An exploded view of an internal gear (Gerotor) pump
Fig. 3.5 Internal gear (Gerotor) pump
Internal gear pumps are exceptionally versatile. While they are often used on
thin liquids such as solvents and fuel oil, they excel at efficiently pumping thick
liquids such as asphalt, chocolate, and adhesives. The useful viscosity range of an
internal gear pump is from 1cPs to over 1,000,000cP.
In addition to their wide viscosity range, the pump has a wide temperature
range as well, handling liquids up to 750F / 400C. This is due to the single point of
end clearance (the distance between the ends of the rotor gear teeth and the head of
the pump). This clearance is adjustable to accommodate high temperature,
maximize efficiency for handling high viscosity liquids, and to accommodate for
wear.
The internal gear pump is non-pulsing, self-priming, and can run dry for
short periods. They're also bi-rotational, meaning that the same pump can be used to

load and unload vessels. Because internal gear pumps have only two moving parts,
they are reliable, simple to operate, and easy to maintain.
Working of Internal GearPumps
Fig. 3.6 Working of Internal gear pump
1. Liquid enters the suction port between the rotor (large exterior gear) and idler (small
interior gear) teeth. The arrows indicate the direction of the pump and liquid.
2. Liquid travels through the pump between the teeth of the "gear-within-a-gear"
principle. The crescent shape divides the liquid and acts as a seal between the suction
and discharge ports.
3. The pump head is now nearly flooded, just prior to forcing the liquid out of the
discharge port. Intermeshing gears of the idler and rotor form locked pockets for the
liquid which assures volume control.
4. Rotor and idler teeth mesh completely to form a seal equidistant from the
discharge and suction ports. This seal forces the liquid out of the discharge port.

Advantages
 Only two moving parts
 Only one stuffing box
 Non-pulsating discharge
 Excellent for high-viscosity liquids
 Constant and even discharge regardless of pressure conditions
 Operates well in either direction
 Can be made to operate with one direction of flow with either
rotation
 Low NPSH required
 Single adjustable end clearance
 Easy to maintain
 Flexible design offers application customization
Disadvantages
 Usually requires moderate speeds
 Medium pressure limitations
 One bearing runs in the product pumped
 Overhung load on shaft bearing
Materials of Construction / Configuration Options
 Externals (head, casing, bracket) - Cast iron, ductile iron, steel, stainless
steel, Alloy 20, and higher alloys.
 Internals (rotor, idler) - Cast iron, ductile iron, steel, stainless steel, Alloy
20, and higher alloys.
 Bushing - Carbon graphite, bronze, silicon carbide, tungsten carbide,
ceramic, colomony, and other specials materials as needed.
 Shaft Seal - Lip seals, component mechanical seals, industry-standard
cartridge mechanical seals, gas barrier seals, magnetically-driven pumps.

3.2 Vane Pump:-
While vane pumps can handle moderate viscosity liquids, they excel
at handling low viscosity liquids such as LP gas (propane), ammonia, solvents,
alcohol, fuel oils, gasoline, and refrigerants. Vane pumps have no internal metal-to-
metal contact and self-compensate for wear, enabling them to maintain peak
performance on these non-lubricating liquids. Though efficiency drops quickly, they
can be used up to 500 cPs / 2,300 SSU.
Vane pumps are available in a number of vane configurations
including sliding vane (left), flexible vane, swinging vane, rolling vane, and external
vane. Vane pumps are noted for their dry priming, ease of maintenance, and good
suction characteristics over the life of the pump. Moreover, vanes can usually
handle fluid temperatures from -32�C / -25�F to 260�C / 500�F and differential
pressures to 15 BAR / 200 PSI (higher for hydraulic vane pumps).
Each type of vane pump offers unique advantages. For example,
external vane pumps can handle large solids. Flexible vane pumps, on the other
hand, can only handle small solids but create good vacuum. Sliding vane pumps can
run dry for short periods of time and handle small amounts of vapor.
Working of Vane Pumps
Despite the different configurations, most vane pumps operate under the
same general principle described below.
Fig 3.7 Working of Vane Pumps

1. A slotted rotor is eccentrically supported in a cycloidal cam. The rotor is located
close to the wall of the cam so a crescent-shaped cavity is formed. The rotor is
sealed into the cam by two side plates. Vanes or blades fit within the slots of the
impeller. As the rotor rotates (yellow arrow) and fluid enters the pump, centrifugal
force, hydraulic pressure, and/or pushrods push the vanes to the walls of the
housing. The tight seal among the vanes, rotor, cam, and side plate is the key to the
good suction characteristics common to the vane pumping principle.
2. The housing and cam force fluid into the pumping chamber through holes in the
cam (small red arrow on the bottom of the pump). Fluid enters the pockets created
by the vanes, rotor, cam, and side plate.
3. As the rotor continues around, the vanes sweep the fluid to the opposite side of
the crescent where it is squeezed through discharge holes of the cam as the vane
approaches the point of the crescent (small red arrow on the side of the
pump). Fluid then exits the discharge port.
Advantages
 Handles thin liquids at relatively higher pressures
 Compensates for wear through vane extension
 Sometimes preferred for solvents, LPG
 Can run dry for short periods
 Can have one seal or stuffing box
 Develops good vacuum
Disadvantages
 Can have two stuffing boxes
 Complex housing and many parts
 Not suitable for high pressures
 Not suitable for high viscosity
 Not good with abrasives

3.3 Lobe Pumps
Lobe pumps are used in a variety of industries including, pulp and paper, chemical,
food, beverage, pharmaceutical, and biotechnology. They are popular in these
diverse industries because they offer superb sanitary qualities, high efficiency,
reliability, corrosion resistance, and good clean-in-place and sterilize-in place
(CIP/SIP) characteristics.
These pumps offer a variety of lobe options including single, bi-wing, tri-lobe
(shown), and multi-lobe. Rotary lobe pumps are non-contacting and have large
pumping chambers, allowing them to handle solids such as cherries or olives without
damage. They are also used to handle slurries, pastes, and a wide variety of other
liquids. If wetted, they offer self-priming performance. A gentle pumping action
minimizes product degradation. They also offer reversible flows and can operate dry
for long periods of time. Flow is relatively independent of changes in process
pressure, so output is constant and continuous.
Rotary lobe pumps range from industrial designs to sanitary
designs. The sanitary designs break down further depending on the service and
specific sanitary requirements. These requirements include 3-A, EHEDG, and
USDA. The manufacturer can tell you which certifications, if any, their rotary lobe
pump meets.

Working of Lobe Pumps
Lobe pumps are similar to external gear pumps in operation in that fluid flows
around the interior of the casing. Unlike external gear pumps, however, the lobes do
not make contact. Lobe contact is prevented by external timing gears located in the
gearbox. Pump shaft support bearings are located in the gearbox, and since the
bearings are out of the pumped liquid, pressure is limited by bearing location and
shaft deflection.
1. As the lobes come out of mesh, they create expanding volume on the inlet side of
the pump. Liquid flows into the cavity and is trapped by the lobes as they rotate.
2. Liquid travels around the interior of the casing in the pockets between the lobes
and the casing -- it does not pass between the lobes.
3. Finally, the meshing of the lobes forces liquid through the outlet port under
pressure.
Lobe pumps are frequently used in food applications because they handle
solids without damaging the product. Particle size pumped can be much larger in
lobe pumps than in other PD types. Since the lobes do not make contact, and
clearances are not as close as in other PD pumps, this design handles low viscosity
liquids with diminished performance. Loading characteristics are not as good as
other designs, and suction ability is low. High-viscosity liquids require reduced

speeds to achieve satisfactory performance. Reductions of 25% of rated speed and
lower are common with high-viscosity liquids.
Advantages
 Pass medium solids
 No metal-to-metal contact
 Superior CIP/SIP capabilities
 Long term dry run (with
lubrication to seals)
Disadvantages
 Requires timing gears
 Requires two seals

3.4 Screw pump
A screw pump is a positive-displacement (PD) pump that uses one or several
screws to move fluids or solids along the screw(s) axis. In its simplest form
(the Archimedes' screw pump), a single screw rotates in a cylindrical cavity, thereby
moving the material along the screw's spindle. This ancient construction is still used
in many low-tech applications, such as irrigation systems and in agricultural
machinery for transporting grain and other solids.
Development of the screw pump has led to a variety of multiple-axis
technologies where carefully crafted screws rotate in opposite directions or remains
stationary within a cavity. The cavity can be profiled, thereby creating cavities where
the pumped material is "trapped".
In offshore and marine installations, a three-spindle screw pump is
often used to pump high-pressure viscous fluids. Three screws drive the pumped
liquid forth in a closed chamber. As the screws rotate in opposite directions the
pumped liquid moves along the screws spindles.
Three-spindle screw pumps are used for transport of viscous fluids
with lubricating properties. They are suited for a variety of applications such as fuel-
injection, oil burners, boosting, hydraulics, fuel, lubrication, circulating, feed and so
on.
Fig 3.9 Screw pump

Advantages of screw pump
1. Slow Speed, Simple and Ruggeddesign
Probably the main and overall advantage of a screw pump is
its superb reliability. The simple design, open structure and slow rotation
speed makes it a heavy duty pumps with minimal wears that operates for
years without trouble.
2. Pumps raw water with heavy solids and floating debris
Because of the open structure and large passage between the
flights a screw pump can pump raw sewage without the need for a coarse
screen before the pump. Both floating debris and heavy solids are simply
lifted up. This saves considerably on equipment costs for a coarse screen or
maintenance!
3. No collectionsump required = minimum head
A screw pump 'scoops' the water directly from the surface and
does not need a collection sump. This keeps the pump head to a minimum.
4. 'Gentle handling' of biologicalflock
The activated return sludge on STP’s is a delicate biological
substance. Because of the low rotational speed and large opening between the
flights, screw pumps do not damage this biological flock (whereas the high
speed rotating centrifugal pumps will completely shred the biological flock).
5. Long lifetime (> 20-40 years)
Screw pumps with typical lifetimes of between 20-40 years
are not unusual.
6. Pump capacityis self-regulating with incoming level

When incoming water level goes down at dry weather flow the screw
pump 'automatically' pumps less water. Ergo: no control system required to adapt
pump performance.
7. Easymaintenance (no 'high skilled' staff required)
A screw pump requires very little maintenance. Compared to
(submersed) centrifugal pumps it is next to nothing. Besides that no ‘highly skilled’
maintenance staffs are required which makes this type of pump very suitable for
remote locations.
8. Constanthigh efficiency with variable capacity
The efficiency-curve of a screw pump is flat on the top. Due
to that efficiency characteristic, the screw pump offers even high efficiency
when it works at 50% of its capacity.
9. Can run without water
A screw pump can operate even when there is no water in the
inlet. Therefore it is not necessary to install expensive measures (level
control etc) to prevent 'dry-running'’. The lower bearing does not need
cooling.

3.5 Piston pump
An axial piston pump has a number of pistons (usually an odd number)
arranged in a circular array within a housing which is commonly referred to as
a cylinder block, rotor or barrel. This cylinder block is driven to rotate about its axis
of symmetry by an integral shaft that is, more or less, aligned with the pumping
pistons (usually parallel but not necessarily).
Fig 3.10 Piston Pump
Mating surfaces.
One end of the cylinder block is convex and wears against a mating
surface on a stationary valve plate. The inlet and outlet fluid of the pump pass
through different parts of the sliding interface between the cylinder block and
valve plate. The valve plate has two semi-circular ports that allow inlet of the
operating fluid and exhaust of the outlet fluid respectively.
No. Part Name
1 Drive Shaft
2
Swash Plate Servo
Ball LH
3
Swash Plate Servo
Ball LH
4 Retainer Plate
5 Pistons
6 Retainer Plate
7 Ball Guide
8 Block Spring
9 Cylinder Block
10 Valve Plate
11 Shaft Bush

 Protruding pistons.
The pumping pistons protrude from the opposite end of the cylinder
block. There are numerous configurations used for the exposed ends of the
pistons but in all cases they bear against a cam. In variable displacement units,
the cam is movable and commonly referred to as a swash plate, yoke or hanger.
For conceptual purposes, the cam can be represented by a plane, the orientation
of which, in combination with shaft rotation, provides the cam action that leads
to piston reciprocation and thus pumping. The angle between a vector normal to
the cam plane and the cylinder block axis of rotation, called the cam angle, is
one variable that determines the displacement of the pump or the amount of fluid
pumped per shaft revolution. Variable displacement units have the ability to vary
the cam angle during operation whereas fixed displacement units do not.
 Reciprocating pistons.
As the cylinder block rotates, the exposed ends of the pistons are
constrained to follow the surface of the cam plane. Since the cam plane is at an
angle to the axis of rotation, the pistons must reciprocate axially as they presses
about the cylinder block axis. The axial motion of the pistons is sinusoidal.
During the rising portion of the piston's reciprocation cycle, the piston moves
toward the valve plate. Also, during this time, the fluid trapped between
the buried end of the piston and the valve plate is vented to the pump's discharge
port through one of the valve plate's semi-circular ports – the discharge port. As
the piston moves toward the valve plate, fluid is pushed or displaced through the
discharge port of the valve plate.
 Effectof precession.
When the piston is at the top of the reciprocation cycle (commonly
referred to as top-dead-center or just TDC), the connection between the trapped
fluid chamber and the pump's discharge port is closed. Shortly thereafter, that
same chamber becomes open to the pump's inlet port. As the piston continues

to presses about the cylinder block axis, it moves away from the valve plate
thereby increasing the volume of the trapped chamber. As this occurs, fluid
enters the chamber from the pump's inlet to fill the void. This process continues
until the piston reaches the bottom of the reciprocation cycle - commonly
referred to as bottom-dead-center or BDC. At BDC, the connection between the
pumping chamber and inlet port is closed.
Shortly thereafter, the chamber becomes open to the discharge port again and the
pumping cycle starts over.
 Variable displacement.
In a variable displacement unit, if the vector normal to the cam plane
(swash plate) is set parallel to the axis of rotation, there is no movement of the
pistons in their cylinders. Thus there is no output. Movement of the swash plate
controls pump output from zero to maximum.
 Pressure.
In a typical pressure-compensated pump, the swash plate angle is
adjusted through the action of a valve which uses pressure feedback so that the
instantaneous pump output flow is exactly enough to maintain a designated
pressure. If the load flow increases, pressure will momentarily decrease but the
pressure-compensation valve will sense the decrease and then increase the swash
plate angle to increase pump output flow so that the desired pressure is restored.
In reality most systems use pressure as a control for this type of pump. The
operating pressure reaches, say, 200 bar (20 MPa or 2900 psi) and the swash
plate is driven towards zero angle (piston stroke nearly zero) and with the
inherent leaks in the system allows the pump to stabilize at the delivery volume
that maintains the set pressure. As demand increases the swash plate is moved to
a greater angle, piston stroke increases and the volume of fluid increases; if the
demand slackens the pressure will rise, and the pumped volume diminishes as
the pressure rises. At maximum system pressure the output is once again almost
zero. If the fluid demand increases beyond the capacity of the pump to deliver,

the system pressure will drop to near zero. The swash plate angle will remain at
the maximum allowed, and the pistons will operate at full stroke. This continues
until system flow-demand eases and the pump's capacity is greater than demand.
As the pressure rises the swash-plate angle modulates to try to not exceed the
maximum pressure while meeting the flow demand.
Advantages
1. Parameter High: Rated high pressure, high speed, large power-driven pump
2. Efficiency, volumetric efficiency is 95% of the total efficiency of about 90%
3. Long life
4. Variable convenient form for
5 More unit power and light weight
6. Piston main components are compressive stress, strength of materials can be fully
utilized
7. Piston pumps have a wide pressure range, can reach high pressures and the
pressure can be controlled without an impact on the rate of flow. Piston pumps have
a continuous rate of discharge.
Disadvantages
• Piston pumps cost more per unit to run compared to centrifugal and roller
pumps. The mechanical parts are prone to wear, so the maintenance costs can be
high. The valves must be resistant to abrasives for large solids to pass through.
Piston pumps are heavy due to their large size and the weight of the crankshaft that
drives the pump.

4) Control components
One of the most important functions in any fluid power system is control. If
control components are not properly selected, the entire system will fail to deliver
the required output. Elements for the control of energy and other control in fluid
power system are generally called “Valves”. It is important to know the primary
function and operation of the various types of control components. This type of
knowledge is not only required for a good functioning system, but it also leads to the
discovery of innovative ways to improve a fluid power system for a given
application
The selection of these control components not only involves the type, but also
the size, the actuating method and remote control capability. There are 3 basic types
of valves.
1. Directional control valves
2. Pressure control valves
3. Flow control valves.
Directional control valves are essentially used for distribution of energy in a fluid
power system. They establish the path through which a fluid traverses a given
circuit. For example they control the direction of motion of a hydraulic cylinder or
motor. These valves are used to control the start, stop and change in direction of
flow of pressurized fluid.
Pressure may gradually buildup due to decrease in fluid demand or due to sudden
surge as valves opens or closes. Pressure control valves protect the system against
such overpressure. Pressure relief valve, pressure reducing, sequence, unloading and
counterbalance valve are different types of pressure control valves.
In addition, fluid flow rate must be controlled in various lines of a hydraulic
circuit. For example, the control of actuator speeds depends on flow rates. This type
of control is accomplished through the use of flow control valves.

4.1 Directional control valves
As the name implies directional control valves are used to control the direction
of flow in a hydraulic circuit. They are used to extend, retract, position or
reciprocate hydraulic cylinder and other components for linear motion. Valves
contains ports that are external openings for fluid to enter and leave via connecting
pipelines, The number of ports on a directional control valve (DCV ) is usually
identified by the term “ way”. For example, a valve with four ports is named as
four-way valve.
Directional control valves can be classified in a number of ways:
1. According to type of construction :
• Poppet valves
• Spool valves
2. According to number of working ports :
• Two- way valves
• Three – way valves
• Four- way valves.
3. According to number of Switching position:
• Two – position
• Three - position
4. According to Actuating mechanism:
• Manual actuation
• Mechanical actuation
• Solenoid ( Electrical ) actuation
• Hydraulic ( Pilot ) actuation
• Pneumatic actuation
• Indirect actuation

1) According to type of construction
1. Poppet Valves:
Directional poppet valves consists of a housing bore in which one or
more suitably formed seating elements ( moveable ) in the form of balls, cones
are situated. When the operating pressure increases the valve becomes more
tightly seated in this design.
The main advantage of poppet valves is;
- No Leakage as it provides absolute sealing.
- Long useful life, as there are no leakages of oil flows.
- May be used with even the highest pressures, as no hydraulic sticking
(pressure dependent deformation) and leakages occurs in the valve.
The disadvantages of these valves are;
- Large pressure losses due to short strokes
- Pressure collapse during switching phase due to negative overlap (connection
of pump, actuator and tank at the same time).

P. V.P. I.T. BUDHGAON 32
2 / 2 DCV (Poppet design) :-
Fig 4.1 2 / 2 DCV Poppet Design
Figure shows a ball poppet type 2 / 2 DCV. It is essentially a check valve as it allows
free flow of fluid only in one direction (P to A) as the valve is opened hydraulically and
hence the pump Port P is connected to port A as shown in fig b. In the other direction the
valve is closed by the ball poppet (note the fluid pressure from A pushes the ball to its seat)
and hence the flow from the port A is blocked .The symbol for this type of design is same as
that of check valve.
No flow
Free flow
Fig. 4.2 Symbol of 2/2 poppet valve ( Check valve )

2. Spool valves:
The spool valve consists of a spool which is a cylindrical member that has
large- diameter lands machined to slide in a very close- fitting bore of the valve body. The
spool valves are sealed along the clearance between the moving spool and the housing. The
degree of sealing depends on the size of the gap, the viscosity of the fluid and especially on
the level of pressure. Especially at high pressures (up to 350 bar) leakage occurs to such a
extent that it must be taken into account when determining the system efficiency. The
amount of leakage is primarily dependent on the gap between spool and housing. Hence as
the operating pressure increases the gap must be reduced or the length of overlap increased.
The radial clearance is usually less than 20 µ. The grooves between the lands provide the
flow passage between ports.

2) According to number of working ports
1. Two-wayvalve ( 2/ 2 DCV):
Fig 4.3 Spool type 2 / 2 DCV
The simplest type of directional control valve is a check valve which is a two way valve
because it contains two ports. These valves are also called as on-off valves because they
allow the fluid flow in only in one direction and the valve is normally closed. Two – way
valves is usually the spool or poppet design with the poppet design more common and are
available as normally opened or normally closed valves. They are usually actuated by pilot
(Hydraulic actuation) but manual, mechanical, solenoid actuated design are also available.
Figure 4.3 above shows Spool type 2 / 2 DCV manually actuated. In Fig 4.3) the port P is
blocked by the action of spring as the valve is UN actuated (absence of hand force). Hence
the flow from port P to A is blocked. When actuated (Presence of hand force) the valve is
opened, thereby connecting port P to A.

2) Three – way valve:
A directional control valve primary function is alternatively to pressurize and exhaust
one working port is called three-way valve. Generally, these valves are used to operate
single- acting cylinders. Three-way directional valves are available for manual, mechanical,
pilot, solenoid actuation. These valves may be two-position, or three -position. Most
commonly they have only two positions, but in some cases a neutral position may be needed.
These valves are normally closed valves (i.e. the pump port is blocked when the valve is not
operating). The three-way valve ports are inlet from the pump, working ports, and exhaust to
tank. These ports are generally identified as follows: P= pressure (Pump) port; A or B =
working port and T = tank port. Figure 4.4 (a) and (b) shows the two positions of the three –
way valve actuated manually by a push button.
a. Spoolposition 1: When the valve is actuated, the spool moves towards left . In this
position flow from pump enters the valve port P and flows out through the port A as shown
by the straight- through line and arrow .In this position, port T is blocked by the spool.
b. Spoolposition 0: when the valve is un-actuated by the absence of hand force, the
valve assumes this position by the action of spring in this position, port P is blocked by the
spool. Flow from the actuator can go to the tank from A to T as shown by straight – through
line and arrow.

Three way valve: P to A connected and T is blocked
Three way valve: P to A connected and T is blocked
Fig 4.4 2 /3 DCV
Symbol 2/ 3 DCV: -
0 1

3. Four - wayDCV: -
These valves are generally used to operate cylinders and fluid motors in both
directions hydraulically. The four ways are Port P that is connected to pump, tank port T,
and two working ports A and B connected to the actuator. The primary function of a four
way valve is to alternately to pressurize and exhaust two working ports A & B. These
valves are available with a choice of actuation, manual, mechanical, solenoid, pilot &
pneumatic. Four-way valve comes with two or three position. One should note that the
graphical symbol of the valve shows only one tank port even though the physical design
may have two as it is only concerned with the function.
3.1. Three positions, four way valves:
These type of DCV consists of three switching position. Most three- position valves
have a variety of possible flow path configurations, but has identical flow path configuration
in the actuated position (position 1 and position 2) and different spring centered flow paths.
When left end of the valve is actuated, the valve will assume 1 position. In this position the
port P to connected to working port A and working port B is connected to T (in some design
P is connected to B, and A to T when left end is actuated ). Similarly when the right end is
actuated, the valve will assume 2 positions. In this position port P is connected to B and
working port A to T. When the valve is un-actuated, the valve will assume its center
position due to the balancing opposing spring forces. It should be noted that a three-position
valve is used whenever it is necessary to stop or hold a actuator at some intermediate
position within its stroke range, or when multiple circuit or functions must be accomplished
from one hydraulic power source.
Three- position, four- way DCV have different variety of center
configurations. The common varieties are the open center, closed center, tandem center,
floating center, & regenerative center with open, closed and tandem are the three basic
types A variety of center configurations provides greater flexibility for circuit design.

3.2 Two-position, Four – way DCV:
These valves are also used to operate double acting cylinder. These valves are
also called as impulse valve as 2 / 4 DCV has only two switching positions, i.e. it has no
mid position. These valves are used to reciprocate or hold and actuating cylinder in one
position. They are used on machines where fast reciprocation cycles are needed. Since
the valve actuator moves such a short distance to operate the valve from one position to
the other, this design is used for punching, stamping and for other machines needing fast
action. Fig a and b shows the two position of 2 / 4 DC
Fig 4.5 Two- position, four – way DCV:
Symbol
1 2

3) Actuation of Directional control valves:
Directional control valves can be actuated by different methods.
1. Manually – actuated Valve:
A manually actuated DCV uses muscle power to actuate the spool. Manual
actuators are hand lever, push button, pedals. The following symbols shows the DCV
actuated manually
1 2
Fig 4.6
Fig 4.6 shows the symbol of 2 / 4 DCV with manually operated by roller tappet to 1
and spring return to 2.
1 2
Fig 4.7
Fig 4.7 shows the symbol of 2 / 4 DCV with manually operated by hand lever to 1 and
spring return to 2. In the above two symbols the DCV spool is returned by springs which
push the spool back to its initial position once the operating force has stopped e.g., letting
go of the hand lever

2. MechanicalActuation:
The DCV spool can be actuated mechanically, by roller and cam, roller and
plunger. The spool end contains the roller and the plunger or cam can be attached to the
actuator (cylinder). When the cylinder reaches a specific position the DCV is actuated. The
roller tappet connected to the spool is pushed in by a cam or plunger and presses on the
spool to shift it either to right or left reversing the direction of flow to the cylinder. A
spring is often used to bring the valve to its center configuration when deactuated.
3. Solenoid-actuatedDCV:
A very common way to actuate a spool valve is by using a solenoid is
illustrated in Fig 4.8. When the electric coil (solenoid) is energized, it creates a magnetic
force that pulls the armature into the coil. This caused the armature to push on the spool rod
to move the spool of the valve.. The advantage of a solenoid lies within its less switching
time.
Fig 4.8 Working of solenoid to shift spool of valve
Figure 4.8 shows the working of a solenoid actuated valve when left coil is
energized, its creates a magnetic force that pulls the armature into the coil. Since the
armature is connected to spool rod its pushes the spool towards right. Similarly when right
coil is energized spool is moved towards left. When both coil is de-energized the spool will
come to the mid position by spring force Figure a shows a symbol for single solenoid used
to actuate 2- position, 4 way valve and b) shows symbol for 2 solenoids actuating a 3-
position valve, 4 way valve.

1 2
Fig 4.8 a) Symbol for Single solenoid-actuated, 2- Position,
4-way spring centered DCV
1 0 2
Fig 4.8b) Symbol for Solenoid actuated, 3- position,
4- way spring centered DCV

4. Hydraulic actuation:
This type actuation is usually known as pilot- actuated valve. The hydraulic
pressure may directly used on the end face of the spool. The pilot ports are located on
the valve ends. Fig 4.9a shows a directional valve where the rate of shifting the spool
from one side to another can be controlled by a needle valve. Fluid entering the pilot
pressure port on the X end flows through the check valve and operates against the
piston. This forces the spool to move towards the opposite position. Fluid in the Y end
(right end ,not shown in the figure) is passed through the adjustable needle valve and
exhausted back to tank. The amount of fluid bled through the needle valve controls how
fast the valve will shift. Fig 4.9b shows the symbol of pilot actuated 2 / 4 DCV.
Fig 4.9a Pilot actuated DCV
A B
Y
X P T
Fig 4.9b Symbol for pilot actuated 2 /4 DCV

5. Pneumatic actuation :
Directional control valve can also be shifted by applying air pressure against a
piston at either end of the valve spool. When air is introduced through the left end
passage (X), its pressure pushes against the piston to shift the spool to the right. Removal
of this left end air supply and introduction of air through the right end passage (Y) causes
the spool to shift to the left. Figure 4.10 shows the symbol for pneumatic actuated 2 / 4
DCV. Note that the shaded arrow represents the pilot actuation as in fig 4.9 and the
unshaded arrow represent pneumatic signal.
A B
X Y
P T
Fig 4.10 Symbol for Pneumatic actuated 2 / 4 DCV

6. Indirect actuation of directional control valve :
We have seen that a directional valve spool can be positioned from one
extreme position to another by actuated it by manually, mechanically, electrically
(solenoid), hydraulic (pilot) and pneumatic. The mode of actuation has no influence on
the basic operation of these switching circuits. However since there is usually not a lot
of force available, direct actuation is restricted to use with rather smaller valves.
Especially with direct actuation, the greatest disadvantage is that the force which can be
developed by them to shift a directional valve spool is limited. As a matter of fact, the
force required to shift a directional spool is substantial in the larger size.
Larger valves are often indirectly actuated in one after the other sequence. First the
smaller valve is directly actuated. Flow from the smaller valve is directed to either side of
the larger valve when shifting is required. The main DCV is referred as pilot actuated
DCV.
The control oil can come from a separate circuit or from the same system’s pressure line.
Pressure for pilot valve operation is usually supplied internally from the pressure passage
in the main valve. These two valves are often incorporated as a single unit. Therefore one
may find it hard to see that it is an indirectly controlled valve. These valves are also
called as Electro-hydraulic operated DCV.

4.2 PRESSURE CONTROL VALVE
These are the units ensuring the control of pressure. A throttling orifice is present in the
valve and by variation of orifice, the pressure level can be controlled or at a particular
pressure, a switching action can be influenced.
Different types of pressure control valves:
Pressure control valves are usually named for their primary function such as
relief valve, sequence valve, unloading valve, pressure reducing valve and counterbalance
valve.
Pressure Relief valve:
The pressure relief valves are used to protect the hydraulic components from
excessive pressure. This is one of the most important components of a hydraulic system and
is essentially required for safe operation of the system. Its primary function is to limit the
system pressure within a specified range. It is normally a closed type and it opens when the
pressure exceeds a specified maximum value by diverting pump flow back to the tank. The
simplest type valve contains a poppet held in a seat against the spring force as shown in
Figure 4.16 the fluid enters from the opposite side of the poppet. When the system pressure
exceeds the preset value, the poppet lifts and the fluid is escaped through the orifice to the
storage tank directly. It reduces the system pressure and as the pressure reduces to the set
limit again the valve closes. This valve does not provide a flat cut-off pressure limit with
flow rate because the spring must be deflected more when the flow rate is higher. Various
types of pressure control valves are discussed in the following sections:

1. Directtype of relief valve
Figure 4.11 Pressure Relief Valve
Schematic of direct pressure relief valve is shown in figure 4.11 .This types of
valves has two ports; one of which is connected to the pump and another is connected to the
tank. It consists of a spring chamber where poppet is placed with a spring force. Generally,
the spring is adjustable to set the maximum pressure limit of the system. The poppet is held
in position by combined effect of spring force and dead weight of spool. As the pressure
exceeds this combined force, the poppet raises and excess fluid bypassed to the reservoir
(tank). The poppet again reseats as the pressure drops below the pre-set value. A drain is also
provided in the control chamber. It sends the fluid collected due to small leakage to the tank
and thereby prevents the failure of the valve.

2. Unloading Valve
Figure 4.12 Unloading Valve
The construction of unloading valve is shown in Figure 4.12 This valve
consists of a control chamber with an adjustable spring which pushes the spool
down. The valve has two ports: one is connected to the tank and another is
connected to the pump. The valve is operated by movement of the spool. Normally,
the valve is closed and the tank port is also closed. These valves are used to permit
a pump to operate at the minimum load. It works on the same principle as direct
control valve that the pump delivery is diverted to the tank when sufficient pilot
pressure is applied to move the spool. The pilot pressure maintains a static pressure
to hold the valve opened. The pilot pressure holds the valve until the pump delivery
is needed in the system. As the pressure is needed in the Hydraulic circuit; the pilot
pressure is relaxed and the spool moves down due to the self-weight and the spring
force. Now, the flow is diverted to the hydraulic circuit. The drain is provided to
remove the leaked oil collected in the control chamber to prevent the valve failure.
The unloading valve reduces the heat buildup due to fluid discharge at a preset
pressure value.

3. Sequence valve
Figure 4.13 Sequence valve
The primary function of this type of valve is to divert flow in a
predetermined sequence. It is used to operate the cycle of a machine automatically.
A sequence valve may be of direct-pilot or remote-pilot operated type.
Schematic of the sequence valve is shown in Figure 4.13 its
construction is similar to the direct relief valve. It consists of the two ports; one
main port connecting the main pressure line and another port (secondary port) is
connected to the secondary circuit. The secondary port is usually closed by the
spool. The pressure on the spool works against the spring force. When the pressure
exceeds the preset value of the spring; the spool lifts and the fluid flows from the
primary port to the secondary port. For remote operation; the passage used for the
direct operation is closed and a separate pressure source for the spool operation is
provided in the remote operation mode.

4. Counterbalance Valve
Figure 4.14 Counter Balance Valve
The schematic of counterbalance valve is shown in Figure 4.14. It is
used to maintain the back pressure and to prevent a load from failing. The
counterbalance valves can be used as breaking valves for decelerating heavy loads.
These valves are used in vertical presses, lift trucks, loaders and other machine tools
where position or hold suspended loads are important. Counterbalance valves work
on the principle that the fluid is trapped under pressure until pilot pressure
overcomes the pre-set value of spring force. Fluid is then allowed to escape, letting
the load to descend under control. This valve is normally closed until it is acted
upon by a remote pilot pressure source. Therefore, a lower spring force is sufficient.
It leads to the valve operation at the lower pilot pressure and hence the power
consumption reduces, pump life increases and the fluid temperature decreases.

5. Pressure Reducing Valve
Figure 4.15 Pressure Reducing Valve
Sometimes a part of the system may need a lower pressure. This can be
made possible by using pressure reducing valve as shown in Figure 4.15. These valves
are used to limit the outlet pressure. Generally, they are used for the operation of
branch circuits where the pressure may vary from the main hydraulic pressure lines.
These are open type valve and have a spring chamber with an adjustable spring, a
movable spool as shown in figure 4.15. A drain is provided to return the leaked fluid
in the spring (control) chamber. A free flow passage is provided from inlet port to the
outlet port until a signal from the outlet port tends to throttle the passage through the
valve. The pilot pressure opposes the spring force and when both are balanced, the
downstream is controlled at the pressure setting. When the pressure in the reduced
pressure line exceeds the valve setting, the spool moves to reduce the flow passage
area by compressing the spring. It can be seen from the figure that if the spring force is
more, the valve opens wider and if the controlled pressure has greater force, the valves
moves towards the spring and throttles the flow.

4.3 Flow Control Valves
Flow-control valves are used to control an actuator’s speed by metering
flow. Metering is measuring or regulating the flow rate to or from an actuator. A water
faucet is an example of a flow-control valve. Flow rate varies as a faucet handle is
turned clockwise or counterclockwise. In a closed position, flow stops. Many flow-
control valves used in fluid-powered systems are similar in design and operation to
water faucets.
In hydraulic circuits, flow-control valves are generally used to control the speed
of hydraulic motors and work spindles and the travel rates of tool heads or slides.
Flow-control valves incorporate an integral pressure compensator, which causes the
flow rate to remain substantially uniform regardless of changes in workload. A no
pressure, compensated flow control, such as a needle valve or fixed restriction, allows
changes in the flow rate when pressure drop through it changes.
Variations of the basic flow-control valves are the flow-control-and-check valves
and the flow-control-and-overload relief valves. Models in the flow-control-and-
check-valve series incorporate an integral check valve to allow reverse free flow.
Models in the flow-control -and- overload-relief-valve series incorporate an integral
relief valve to limit system pressure. Some of these valves are gasket-mounted, and
some are panel-mounted.

1 Gate Valve
In this type of valve, a wedge or gate controls the flow. To open and close a passage, a
handwheel moves a wedge or gate up and down across a flow line. Figure 4.16, shows
the principal elements of a gate valve. Area A shows the line connection and the
outside structure of the valve; area B shows the wedge or gate inside the valve and the
stem to which the gate and the handwheel are attached. When the valve is opened, the
gate stands up inside the bonnet with its bottom flush with the wall of the line. When
the valve is closed, the gate blocks the flow by standing straight across the line where
it rests firmly against the two seats that extend completely around the line.
A gate valve allows a straight flow and offers little or no resistance to the fluid flow
when the valve is completely open.
Sometimes a gate valve is in the partially open position to restrict the flow rate.
However, its main use is in the fully open or fully closed positions. If the valve is left
partly open, the Valve's face stands in the fluid flow, which will act on the face and
cause it to erode
Fig. 4.16 Gate valve

2. Plug or glove valve
Fig. 4.17 Plug or glove valve
The plug valve is quite commonly used valve. It is also termed as glove valve.
Schematic of plug or glove valve is shown in Figure. This valve has a plug which can
be adjusted in vertical direction by setting flow adjustment screw. The adjustment of
plug alters the orifice size between plug and valve seat. Thus the adjustment of plug
controls the fluid flow in the pipeline. The characteristics of these valves can be
accurately predetermined by machining the taper of the plug. The typical example of
plug valve is stopcock that is used in laboratory glassware. The valve body is made of
glass or Teflon. The plug can be made of plastic or glass. Special glass stopcocks are
made for vacuum applications. Stopcock grease is used in high vacuum applications to
make the stopcock air-tight.

3. Butterfly valve
A butterfly valve is shown in Figure. It consists of a disc which can rotate inside the
pipe. The angle of disc determines the restriction. Butterfly valve can be made to any
size and is widely used to control the flow of gas. These valves have many types
which have for different pressure ranges and applications. The resilient butterfly valve
uses the flexibility of rubber and has the lowest pressure rating. The high performance
butterfly valves have a slight offset in the way the disc is positioned. It increases its
sealing ability and decreases the wear. For high-pressure systems, the triple offset
butterfly valve is suitable which makes use of a metal seat and is therefore able to
withstand high pressure. It has higher risk of leakage on the shut-off position and
suffers from the dynamic torque effect. Butterfly valves are favored because of their
lower cost and lighter weight. The disc is always present in the flow therefore a
pressure drop is induced regardless of the valve position.
Fig. 4.18 Butterfly valve

4. Ball Valve
The ball valve is shown in Figure 4.19. This type of flow control valve uses a ball
rotated inside a machined seat. The ball has a through hole as shown in Figure. It has
very less leakage in its shut -off condition. These valves are durable and usually work
perfectly for many years. They are excellent choice for shutoff applications. They do
not offer fine control which may be necessary in throttling applications. These valves
are widely used in industries because of their versatility, high supporting pressures (up
to 1000 bar) and temperatures (up to 250°C). They are easy to repair and operate.
Fig 4.19 Ball valve

5. Balancedvalve
Schematic of a balanced valve is shown in figure 4.20. It comprises of two
plugs and two seats. The opposite flow gives little dynamic reaction onto the actuator
shaft. It results in the negligible dynamic torque effect. However, the leakage is more
in these kind of valves because the manufacturing tolerance can cause one plug to seat
before the other. The pressure-balanced valves are used in the houses. They provide
water at nearly constant temperature to a shower or bathtub despite of pressure
fluctuations in either the hot or cold supply lines.
Figure 4.20 Balanced valves

5) Actuators:-
A hydraulic actuator receives pressure energy and converts it to
mechanical force and motion. An actuator can be linear or rotary. A linear
actuator gives force and motion outputs in a straight line. It is more
commonly called a cylinder but is also referred to as a ram, reciprocating
motor, or linear motor. A rotary actuator produces torque and rotating motion.
It is more commonly called a hydraulic motor or motor.
5.1 Cylinders
A cylinder is a hydraulic actuator that is constructed of a piston or
plunger that operates in a cylindrical housing by the action of liquid under
pressure. Figure shows the basic parts of a cylinder. Cylinder housing is a
tube in which a plunger (piston) operates. In a ram-type cylinder, a ram
actuates a load directly. In a piston cylinder, a piston rod is connected to a
piston to actuate a load. An end of a cylinder from which a rod or plunger
protrudes is a rod end. The opposite end is a head end. The hydraulic
connections are a head-end port and a rod-end port (fluid supply).
a. Single-Acting Cylinder.
This cylinder only has a head-end port and is operated
hydraulically in one direction. When oil is pumped into a port, it pushes on a
plunger, thus extending it. To return or retract a cylinder, oil must be
released to a reservoir. A plunger returns either because of the weight of a
load or from some mechanical force such as a spring. In mobile equipment,
flow to and from a single-acting cylinder is controlled by a reversing
directional valve of a single-acting type.
b. Double-Acting Cylinder.
This cylinder must have ports at the head and rod ends.
Pumping oil into the head end moves a piston to extend a rod while any oil
in the rod end is pushed out and returned to a reservoir. To retract a rod,
flow is reversed. O il from a pump goes into a rod end, and a head-end port is
connected to allow return flow. The flow direction to and from a double-
acting cylinder can be controlled by a double-acting directional valve or by
actuating a control
of a reversible pump.

c. Differential Cylinder.
In a differential cylinder, the areas where pressure is applied on a
piston are not equal. On a head end, a full piston area is available for applying
pressure. At a rod end, only an annular area is available for applying pressure.
A rod’s area is not a factor, and what space it does take up reduces the volume
of oil it will hold. Two general rules about a differential cylinder are that. With
an equal GPM delivery to either end, a cylinder will move faster when
retracting because of a reduced volume capacity.
With equal pressure at either end, a cylinder can exert more force
when extending because of the greater piston area. In fact, if equal pressure is
applied to both ports at the same time, a cylinder will extend because of a
higher resulting force on a head end.
d. Piston-Type Cylinder.
In his cylinder, a cross-sectional area of a piston head is referred to
as a piston-type cylinder. A piston-type cylinder is used mainly when the push
and pull functions are needed.
A single-acting, piston-type cylinder uses fluid pressure to apply force in
one direction. In some designs, the force of gravity moves a piston in the
opposite direction. However, most cylinders of this type apply force in both
directions. Fluid pressure provides force in one direction and spring tension
provides force in the opposite direction.
Fig 5.1 Piston Type cylinder
Figure shows a single-acting, spring- loaded, piston-type cylinder. In this
cylinder, a spring is located on the rod side of a piston. In some spring-loaded
cylinders, a spring is located on a blank side, and a fluid port is on a rod end of a
cylinder.
Most piston-type cylinders are double-acting, which means that
fluid under pressure can be applied to either side of a piston to provide
movement and apply force in a corresponding direction. Figure shows a double-
acting piston-type cylinder this cylinder contains one piston and piston-rod
assembly and operates from fluid flow in either direction. The two fluid ports,
one near each end of a cylinder, alternate as an inlet and an outlet, dependin g
on the directional-control valve flow direction. This is an unbalanced cylinder,

which means that there is a difference in the effective working area on the two
sides of a piston. A cylinder is normally installed so that the head end of a
piston carries the greater load; that is, a cylinder carries the greater load
during a piston-rod extension stroke.
Figure shows a balanced, double-acting, piston-type cylinder. The
effective working area on both sides of a piston is the same, and it
exerts the same force in both directions.
5.2. Double-acting, piston-type cylinder

e. Cushioned Cylinder.
To slow an action and prevent shock at the end of a piston
stroke, some actuating cylinders are constructed with a cushioning
device at either or both ends of a cylinder. This cushion ids usually
a metering device built into a cylinder to restrict the flow at an
outlet port, thereby slowing down the motion of a piston .Figure
shows a cushioned actuating cylinder
Fig 5.3 Cushioned, actuating cylinder

f. Lockout Cylinders.
A lockout cylinder is used to lock a suspension
mechanism of a tracked vehicle when a vehicle functions as a
stable platform. A cylinder also serves as a shock absorber when
a vehicle is moving. Each lockout cylinder is connected to a road
arm by a control lever. When each road wheel moves up, a
control lever forces the respective cylinder to compass..
Hydraulic fluid is forced around a piston head through
restrictor ports causing a cylinder to act as a shock absorber.
When hydraulic pressure is applied to an inlet port on each
cylinder’s connecting eye, an inner control-valve piston is forced
against a spring in each cylinder. This action closes the
restrictor ports, blocks the main piston’s motion in each
cylinder, and locks the suspension system

5.2 Hydraulic Motors
Hydraulic motors convert hydraulic energy into
mechanical energy. In industrial hydraulic circuits, pumps
and motors are normally combined with a proper valving and
piping to form a hydraulic-powered transmission. A pump,
which is mechanically linked to a prime mover, draws fluid
from a reservoir and forces it to a motor. A motor, which is
mechanically linked to the workload, is actuated by this flow so
that motion or torque, or both, are conveyed to the work.
Figure 4-9 shows the basic operations of a hydraulic motor.
Figure 5.4 Basic operations of a hydraulic motor
The principal ratings of a motor are torque, pressure, and
displacement. Torque and pressure ratings indicate how much
load a motor can handle. Displacement indicates how much flow is
required for a specified drive speed and is expressed in cubic
inches per revolutions, the same as pump displacement.
Displacement is the amount of oil that must be pumped into a
motor to turn it one revolution. Most motors are fixed-
displacement; however, variable-displacement piston motors are
in use, mainly in hydrostatic drives. The main types of motors are
gear, vane, and piston. They can be unidirectional or reversible.
(Most motors designed for mobile equipment are reversible.)

Fig 5.5 Gear-type motor
a. Gear-Type Motors.
Figure shows a gear-type motor. Both gears are driven gears, but
only one is connected to the output shaft. Operation is essentially the
reverse of that of a gear pump. Flow from the pump enters chamber A
and flows in either direction around the inside surface of the casing,
forcing the gears to rotate as indicated. This rotary motion is then
available for work at the output shaft.

Fig 5.6 Vane-type motor
b. Vane-Type Motors.
Figure shows a vane-type motor. Flow from the pump enters the
inlet, forces the rotor and vanes to rotate, and passes out through the
outlet. Motor rotation causes the output shaft to rotate. Since no
centrifugal force exists until the motor begins to rotate, something,
usually springs, must be used to initially hold the vanes against the
casing contour. However, springs usually are not necessary in vane-type
pumps because a drive shaft initially supplies centrifugal force to ensure
vane-to-casing contact.
Fig 5.7 Pressure differential on a vane-type motor

Vane motors are balanced hydraulically to prevent a rotor from side-
loading a shaft. A shaft is supported by two ball bearings. Torque is
developed by a pressure difference as oil from a pump is forced through a
motor. Figure shows pres-sure differential on a single vane as it passes
the inlet port. On the trailing side open to the inlet port, the vane is
subject to full system pressure. The chamber leading the vane is subject
to the much lower outlet pressure. The difference in pressure exerts the
force on the vane that is, in effect, tangential to the rotor. This pressure
difference is effective across vanes 3 and 9 as shown in Figure. The other
vanes are subject to essentially equal force on both sides. Each will
develop torque as the rotor turns. Figure shows the flow condition for
counterclockwise rotation as viewed from the cover end. The body port is
the inlet, and the cover port is the outlet. Reverse the flow, and the
rotation becomes clockwise.
In a vane-type pump, the vanes are pushed out against a cam ring by
centrifugal force when a pump is started up. A design motor uses steel-
wire rocker arms to push the vanes against the cam ring. The arms pivot
on pins attached to the rotor. The ends of each arm support two vanes
that are 90 degrees apart. When the cam ring pushes vane A into its slot,
vane B slides out. The reverse also happens. A motor’s pressure plate
functions the same as a pump's. It seals the side of a rotor and ring
against internal leakage, and it feeds system pressure under the vanes to
hold them out against a ring. This is a simple operation in a pump
because a pres-sure plate is right by a high-pressure port in the cover.
Fig 5.8 Rocker arms pushing vanes in a pump

6) Fittings and Connectors
Fittings are used to connect the units of a fluid-powered system,
including the individual sections of a circulatory system. Many
different types of connectors are available for fluid-powered systems.
The type that you will use will depend on the type of circulatory system
(pipe, tubing, or flexible hose), the fluid medium, and the maximum
operating pressure of a system. Some of the most common types of
connectors are described below:
a. Threaded Connectors.
Threaded connectors are used in some low-pressure liquid-powered
systems. They are usually made of steel, copper, or brass, in a variety
of designs. The connectors are made with standard female threading
cut on the inside surface. The end of the pipe is threaded with outside
(male) threads for connecting.
Fig 6.1 Threaded-pipe connectors

Standard pipe threads are tapered slightly to ensure tight
connections.
To prevent seizing (threads sticking) apply a pipe-thread
compound to the threads. Keep the two end threads free of the
compound so that it will not contaminate the fluid. Pipe
compound, when improperly applied, may get inside the lines and
harm the pumps and the control equipment.
b. Flared Connectors.
The common connectors used in circulatory systems consist
of tube lines. These connectors provide safe, strong, dependable
connections without having to thread, weld, or solder the tubing. A
connector consists of a fitting, a sleeve, and a nut
Fig. 6.2 Flared tube connector
Fittings are made of steel, aluminum alloy, or bronze. The fittings
should be of a material that is similar to that of a sleeve, nut, and
tubing. Fittings are made in unions, 45- and 90-degree elbows, Ts, and
various other shapes. Figure shows some of the most common fittings
used with flared connectors.
Fittings are available in many different thread combinations.
Unions have tube connections on each end; elbows have tube connections
on one end and a male pipe thread, female pipe thread, or a tube
connection on the opposite end; crosses and Ts have several different
combinations.
Tubing used with flared connectors must be flared before being
assembled. A nut fits over a sleeve and, when tightened, draws the
sleeve and tubing flare tightly against a male fitting to form a seal. A
male fitting has a cone-shaped surface with the same angle as the

inside of a flare. A sleeve supports the tube so that vibration does not
concentrate at the edge of a flare but that it does distribute the
shearing action over a wider area for added strength. Tighten the
tubing nuts with a torque wrench to the value specified in applicable
regulations.
If an aluminum alloy flared connector leaks after tightening to the
specified torque, do not tighten it further. Disassemble the leaking
connector and correct the fault. If a steel connector leaks, you may
tighten it 1/6 turn beyond the specified torque in an attempt to stop
the leak. If you are unsuccessful, disassemble it and repair it.
Flared connectors will leak if—
· A flare is distorted into the nut threads.
· A sleeve is cracked.
· A flare is cracked or split.
· A flare is out-of-round.
· A flare is eccentric to the tube’s OD.
· A flare's inside is rough or scratched.
· A fitting cone is rough or scratched.
· The threads of a fitting or nut are dirty, damaged, or broken.

Fig 6.3 Flared-tube fittings

c. Flexible-Hose Couplings.
If hose assembly is fabricated with d attachable couplings (Figure ),
use the same couplings when reacting the replacement assembly, as
long as the failure (leak) did not occur at a coupling. Failure occurred
at a coupling, card it.
Fig 6.4 Field-attachable couplings
When measuring a replacement hose assembly for screw on a
pings measure from the edge a retaining bolt.
Hose in hose blocks and n in a bench vice for effective
cutting, a blade should have 24 or 32 teeth per inch. To remove an
old coupling on a hose assembly that is fabricated with
permanently attached couplings, you just discard the entire
assembly.

d. Reusable Fittings.
To use a skived fitting you must strip (skive) the hose to a length
equal to that from a notch on a fitting to the end of the fitting. (A
notch on a female portion of a fitting in Figure indicates it to be a
skived fitting.) To assemble a conductor using skived fittings—
Fig. 6.5 permanently attached couplings
· Determine the length of the skive.
· Make a cut around the hose with a sharp knife. Make sure
that you cut completely through the rubber cover of the hose.
· Cut lengthwise to the end of the hose. Lift the hose flap and
remove it with pliers.
· Repeat the process on the opposite end of the hose.
· Place the female portion of the fitting in a bench vice and
secure it in place.
· Lubricate the skived portion of the hose with hose
lubricant (hydraulic fluid or engine oil, if necessary).
· Insert the hose into the female socket and turn the hose
counterclockwise until it bottoms on the shoulder of the
female socket, then back off 1/4 turn.
· Place the female socket in an upright position (Figure 6.5)
and insert the male nipple into the female socket.
· Turn the male nipple clockwise (Figure 6.5) until the hex is
within 1/32 inch of the female socket.
· Repeat the above process on the opposite end of the hose.

7) CUTTING PROCEDURE
1. Hydraulic Vane Pump:-
1) First of all the vane pump oil is drained.
2) After washing the marking is done
3) Then the cut the cover on the marking part with the help of hacksaw.
4) After then we cuts the spring assembly in pump & also the body by using hand
grinder.
5) The grinder is used to finish the rough cutting surface. In small area finishing
the files are used.
6) After the finishing clean & paints with the color to inner & outer side & also
paint & dry in the air.
7) After this process all the removed part assemble it.
8) Then we paint the parts with various shades of color.
Fig. 7.1 Cutting & grinding of vane pump

2. GearPump:-
1) First of all the Gear pump oil is drained.
2) The gear pump cover is open, it clean with cotton, & kerosene. Then foam
water is used to washing.
3) After washing the marking is done on the gear pump.
4) Then the cut the cover of marking point with the help of hacksaw.
5) Then we cut the body of pump by using hand grinder.
6) The grinder is used to finish the rough cutting surface in small area & for
finishing the file is used.
7) After finishing it clean & paints with the color & to inner & outer side.
8) After this process both the gears are assemble in casing.
Fig. 7.2 Dismantling & cutting of gear pump

3. Double Acting Cylinder:-
1) First cleaning the double acting cylinder in outside.
2) Then we remove connector from cylinder, bolt or stud & dismantle all part of
cylinder like piston, piston rod, oil seal etc.
3) Then we again clean the all part with kerosene.
4) Then we cut cylinder block by using grinder.
5) After cutting us removes the sharp edges by using file.
6) Then we paint it.
4. Single Acting Cylinder:-
1) First cleaning the single acting cylinder in outside then we remove connector
from cylinder, bolt or stud & dismantle all part of cylinder like piston, piston
rod, oil seal etc.
2) Then we again clean the all part with kerosene.
3) Then we cut the cylinder block by using hacksaw & grinder.
4) Then we paint with red color on cutting edge.
5) After drying the color we assemble the all parts & then mount on a board
with the help of clamps.

5. FlowControl Valve:-
1) First cleaning the flow control valve in outside.
2) After cleaning the throttle position & diverting position by kerosene.
3) Marking is done on flow control valve.
4) Then cut the flow control valve block by using grinder.
Fig. 7.3 cutting of flow control valve
6. Hoses:-
1) Firstly cleanthe hosesoutside byusingcloth.
2) Thenwe cut the hosesbyusingof hacksaw.
3) Thenpaintit withredcolor.
8) TOOLS AND EQUIPMENT
Grinders and Grinding Machines Information:-
Grinders and grinding machines use an abrasive that is bonded to a wheel, belt
or disc to remove material and improve surface finish. Dev ices can be pneumatically
driven or powered by a combustion engine or electric motor.
Grinders and grinding machines can use single phase or three phase power and
are available in a range of voltages 60 Hz power is used in North America. 50 Hz
power is used internationally.
Features:-
 Optional features include
 Cabinets and enclosures

 Double sided disks
 Dressing systems
 Dust collection or filtration systems
RelatedProducts & Services:-
Honing, Lapping, and super finishing Machines
Honing, lapping and super finishing equipment are used to improve surface
finish or geometry to tight tolerances.
Hacksaw:-
A hacksaw is a fine tooth hand saw with a blade held under tension in a frame,
used for cutting materials such as metal or plastics. Hand held hacksaws consist of a
metal arch with a handle, usually a pistol grip, with pins for attaching a narrow
disposable blade. A screw or other mechanism is used to put the thin blade under
tension. Te blade can be mounted with the teeth facing toward or away from the
handle, resulting in cutting action on either the push or pull stroke.
On the push stroke, the arch will flex slightly, decreasing the tension on the
blade, often resulting in an increased tendency of the blade to buckles and crack.
Cutting on the pull stroke increases the blade tension and will result in greater control
for the cut and longer blade life.

Blades:-
Blades are available in standardized lengths, usually 10 or 12 inches for a
standard hand hacksaw. Junior hacksaws are half this size. Powered hacksaws may
use large blades in a range of sizes, or small machines may use the same hand blades.
Electric hacksaw:-
A power hacksaw (or electric hacksaw) is a type of hacksaw that is powered
either by its own electric motor or connected to a stationary engine. Most power
hacksaws are stationary machines but some portable models do exist. Stationary
models usually have a mechanism to lift up the saw blade on the return stroke and
some have a coolant pump to prevent the saw blade from overheating.

9) Costing
Sr. no. Object Amount
1 Gear Pump 2,500
2 Vane Pump 3,500
3 Single Acting cylinder 1,500
4 Double Acting cylinder 3,000
5 Flow control valve 950
6 Direction Control Valve 3,000
7 Connectors 600
8 Hoses 600
9 Coupler 900
10 Boards 850
11 Nut &bolt 60
12 Fabrication 600
13 Color 500
14 Painting 500
15 Kolhapur visit 1,000
16 Traveling 200
Total 20,150

10) CONCLUSION
The main purpose of our project is to collect all information about hydraulic
devices. In this project we show all internal parts of gear pump and vane pump, as
well as try to show Direction control valve, flow control valve, single and double
acting cylinder, Hose pipes. With its mechanism in board mounted condition.& it’s
works properly.
This project is good collection of Gear pump, vane pump and other parts. We
try to develop our automobile lab, hence we select this project.

11) Reference
1. Chapter2_Hydraulics_control_in_machine_tools nptel.
2. Hydraulic Pumps – pumpschool.com
3. en.wikipedia.org/wiki/Hydraulic pump
4. Field Manual, No. 5-499, Headquarters, Department of the
Army.
5. BASIC HYDRAULIC SYSTEMS AND COMPONENTS,
Sub course Number AL 0926, EDITION A,US Army Aviation
Logistics School Fort Eustis, Virginia 23604-54394, Credit
Hours, Edition Date: September 1994
6. Collage library.
7. McNeil, Ian (1990). An Encyclopedia of the History of Technology.
London: Rout ledge. p. 961. ISBN 0-415-14792-1.
8. Jump up Housel, David A. (1984), From the American System to Mass
Production, 1800-1932: The Development of Manufacturing Technology
in the United States, Baltimore, Maryland: Johns Hopkins University
Press, ISBN 978-0-8018-2975-8, LCCN 83016269
9. Jump up to: Hunter, Louis C.; Bryant, Lynwood (1991). A History of
Industrial Power in the United States, 1730-1930, Vol. 3: The
Transmission of Power. Cambridge, Massachusetts, London: MIT
Press. ISBN 0-262-08198-9.

Important project report 1

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (7)

Similar to Important project report 1

Similar to Important project report 1 (20)

Important project report 1