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© Er. GAUTAM MALIK
CHITKARA UNIVERSITY
BASIC HYDRAULICS
(LECTURE NOTES SERIES FOR DR. REDDY Labs BADDI)
Er. Anoop Aggarwal
(Associate Professor, Deptt. Of Mechanical Engineering)
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Fluid Power Machine
© Er. Anoop Aggarwal
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Hydraulic Systems
Fluid power systems that
use oil or another liquid.
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Fluid power systems work by force
being applied to a fluid (gas or
liquid) , then the energy of the
fluid, under pressure, transfers its
energy to a mechanically device to
perform work.
How does a fluid power system work?
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Pressure
The amount of force
distributed over a unit of area,
usually expressed in pounds
per square inch.
Pressure = Force (F)
Area (A)
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PASCAL LAW
© Er. Anoop Aggarwal
When a force is applied to a confined
fluid, the increase in pressure is
transmitted equally to all parts of the
fluid.
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Pascal’s Principle
All have equal pressure
Force
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Transmitting Pressure in a
Fluid • When force is applied to a confined
fluid, the change in pressure is
transmitted equally to all parts of the
fluid.
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9
Pascal Law
© Er. Anoop Aggarwal
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A closed hydraulic system such as the one diagrammed here
provides a mechanical advantage similar to that of a simple lever. In
a closed fluid system a small force exerted on a small cylinder could
balance a large force on a large cylinder. For example, 1 pound of
force applied to a 1 square inch cylinder can balance 100 pounds of
force on a 100 square inch cylinder. This is how we can move a 100
pound we ight using only 1 pound of force. The distance the 100
pounds will travel is inversely proportional to the distance the
applied force travels. That means if we move a 1 square inch
cylinder a distance of one inch, we only move the 100 square inch
cylinder 1/100th of an inch
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© Er. Anoop Aggarwal
4 N
.002m2
20m2
1. What is the pressure of the left piston?
2. What is the pressure of the right Piston?
2000Pa
P= F/a = 4/.002 = 2000Pa
3. What is the total force of the
right Piston?
40,000N F=Pa= 2000N/m2 x 20m2 =
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Hydraulic Brake
© Er. Anoop Aggarwal
• The hydraulic brake
system of a car
multiplies the force
exerted on the brake
pedal.
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Hydraulic System
© Er. GAUTAM MALIK
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Components
• Hydraulic pump or air compressor, which converts mechanical
power to fluid power.
• Cylinder or motor, which converts fluid power to linear or
rotary mechanical power.
• Valves, which control the direction, pressure and rate of flow.
• Filters, regulators and lubricators, which condition the fluid.
• Manifolds, hose, tube, fittings, couplings, etc., which conduct
the fluid between components.
• Sealing devices, which help contain the fluid.
• Accumulators and reservoirs, which store the fluid.
• Instruments such as pressure switches, gauges, flow meters,
sensors and transducers, which are used to help monitor the
performance of a fluid power system.
© Er. Anoop Aggarwal
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© Er. Anoop Aggarwal
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Fluid power applications • Mobile: Here fluid power is used to transport, excavate and lift
materials as well as control or power mobile equipment. End use
industries include construction, agriculture, marine and the military.
Applications include backhoes, graders, tractors, truck brakes and
suspensions, spreaders and highway maintenance vehicles.
• Industrial: Here fluid power is used to provide power transmission and
motion control for the machines of industry. End use industries range
from plastics working to paper production. Applications include
metalworking equipment, controllers, automated manipulators,
material handling and assembly equipment.
• Aerospace: Fluid power is used for both commercial and military
aircraft, spacecraft and related support equipment. Applications
include landing gear, brakes, flight controls, motor controls and cargo
loading equipment.
© Er. Anoop Aggarwal
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Applications
© Er. Anoop Aggarwal
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Applications
© Er. Anoop Aggarwal
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Applications
© Er. Anoop Aggarwal
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Pump types
© Er. Anoop Aggarwal
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Hydraulic and Pneumatic Systems 21
External gear pump
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Hydraulic and Pneumatic Systems 22
Pump types
Off-centered internal gear pump
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Hydraulic and Pneumatic Systems 23
Pump types
Centered internal gear pump / gerotor pump
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Hydraulic and Pneumatic Systems 24
Pump types
Screw pump
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Hydraulic and Pneumatic Systems 25
Pump types
Vane pump
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Hydraulic and Pneumatic Systems 26
Pump types
Axial piston pump with tilting block
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Hydraulic and Pneumatic Systems 27
Pump types
Axial piston pump with tilting cam plate
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Hydraulic and Pneumatic Systems 28
Radial piston pump
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Functions of Fluid
• Primary function is to create force and motion
as flow is converted to pressure near the point
of use.
• Second by occupying the space between metal
surfaces, the fluid forms a seal, which provides
a pressure barrier and helps exclude
contaminants.
• A third function—often misunderstood is
lubrication of metal surfaces.
• The fourth and final function provided by
hydraulic fluid is cooling of system components.
© Er. Anoop Aggarwal
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Types of Hydraulic Oil
• There are many types of hydraulic fluids, of
which the most common would be mineral
oil, polyaphaolefin and organophosphate
ester.
• Others are based on glycol esters and
ethers, vegetable oil,castor oil, or silicone.
• Certain hydraulic fluids are produced from
crude oil and others are manufactured by
many companies.
© Er. Anoop Aggarwal
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Cylinders
© Er. Anoop Aggarwal
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Single Acting & Double Acting Cylinder
© Er. Anoop Aggarwal
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Telescopic Cylinder
© Er. Anoop Aggarwal
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Hydraulic Gear Motor
© Er. Anoop Aggarwal
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Basic Hydraulic Circuit
© Er. Anoop Aggarwal
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Pressure Sequence Circuit
© Er. Anoop Aggarwal
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Regeneration circuit
© Er. GAUTAM MALIK
Regenerative Circuit. Regenerative circuits are used when it is desirable to
rapidly advance an actuator into position to reduce cycle time. When
configured as a regenerative system, cylinders can be advanced more rapidly
than in normal operation with the pump flow rate alone. In order to accomplish
regeneration, the fluid leaving the rod end of the cylinder is routed back to the
cap side of the cylinder to combine with the pump flow rate from the pump
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Types of Maintenance
© Er. Anoop Aggarwal
• Maintenance may be classified into four categories:
• (some authors prefer three categories- scheduled
and preventive maintenances are merged)
1. Corrective or Breakdown maintenance
2. Scheduled maintenance
3. Preventive maintenance
4. Predictive (Condition-based) maintenance
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Purpose
© Er. Anoop Aggarwal
• Attempt to maximize performance of
production equipment efficiently and
regularly
• Prevent breakdown or failures
• Minimize production loss from failures
• Increase reliability of the operating
systems
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Safety
© Er. Anoop Aggarwal
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© Er. Anoop Aggarwal
