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Introduction to Hydraulics
Dowell
UTCUTC
Module CT02
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Objective
In this module, you will learn :
CTU Hydraulic systems.
Advantage of hydraulic systems.
Principal and operation of hydraulic circuits.
Operation and application for each basic component.
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CTU Hydraulic Pumps
Pump Circuit Pressure
(PSI)
Pump Flow Rate
(GPM)
Injector - 1 3,000 30
Injector - 2 3,000 60
Reel 2,500 16
Level Wind(Override)
2,500 30
BOPs 3,000 12
Priority 2,000 12
Aux. 3,000 30
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What is Hydraulics ?
Hydraulics is the study of devices that use the pressure in
a confined fluid to generate, transmit, and control power.
A device that uses the impact or kinetic energy in a liquid to
transmit power is a hydrodynamic device. e.g the water-wheel
(Pelton turbine)
A device operated by the force applied to a confined liquid is a
hydrostatic device. (eg. a hydraulic car-jack)
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Fundamentals
Pascals Law
Pressure applied on a confined fluid is transmitted undiminished in
all directions, and acts with equal force on equal areas, and at
right angles to them.
Law of Conservation of Energy
Energy can neither be created nor destroyed.
Bernoullis principle
If the flow rate is constant, the sums of the kinetic energy andpressure energy at various points in a system are constant.
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Mechanical Advantage
1 sq. in. 8 sq. in.
100 lbs800 lbs
800 lbs100 lbs
8 ft 1 ft
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Advantages of Hydraulic Systems
Variable speed
Reversible
Overload protection / stalling
High bhp/kg ratios
Reliability and ease of maintenance
Flexibility of placement
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Hydraulic Fluid
Transmits power
Low viscosity - hence low friction.
Incompressible
Lubricates
All hydraulic components internally lubricated Seals
Metal-to-meal seals work because of close tolerances and
viscosity of hydraulic oil.
Cools
And... Additional properties such as resistance to foaming, protection
against rust and oxidation
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Viscosity
Viscosity is the measure of the fluids resistance to flow.
A high viscosity is desirable for maintaining seal between
mating surfaces. But...
Too high a viscosity will lead to high friction, increased powerlosses, higher operating temperatures.
Too low a viscosity will cause increased internal leakage, lower
pump efficiency, and possible breakdown of oil under heavy loads.
Typical hydraulic grades - ISO32, or SAE10W
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Symbols
Pump Motor
Relief valve
Reservoir
A pilot line operates a valve
or other controls Pressure line is a
working line
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Symbols
Single Acting Cylinder Double Acting Cylinder
Piston Rod
Hydraulic Rams
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Symbols
IN
OUT
Pilot Line denotes
operation by pressure
Arrow showes flow path
and direction
Relief valve (Infinite Positioning)
Arrow indicates
adjustable
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Symbols
Port Connections aredrawn to center or neutral
position
Three envolopes means
the valve has three positions
Arrows show flow
path and direction
Directional Valve (Finite Positioning)
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Symbols
Horizontal bars
indicates infinite
positioning ability
Directional Valve (Infinite Positioning)
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Check Valve
IN OUT
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2 Way Spool Valve
Pr to B
A Blocked
A B
Pr to A
B Blocked
A B
A B
P T
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4 Way Spool Valve
Pr to B
A to tank
A B
Pr to A
B to tank
A B
A B
TP
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Direct Acting ReliefValve
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Balanced Piston ReliefValve
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Pilot-operated pr.-reducing valve
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Unloading Valve
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Counter Balance Valve
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Vanes
Drive shaft Rotor
system pressure
pressure on this vanegives rise to a force
the force acting on the vanecreates a torque on the shaft
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Vane Motor - Unbalanced
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Vane Motor - Balanced
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In-Line Pistons Motor
oil under pressure
at the inlet...
swash plate
drive shaftshoe retainer plate
pistonscylinder block
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Vane Pump
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Vane Pump - Contd...
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Gear Pump
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Lobe Pump
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Radial Pistons Motor
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Reservoir
Stores and supplies hydraulic fluid
Size (gal) > 2xpump(gpm) < 3xpump(gpm)
Allows oil to cool
Baffle plate enhances cooling, prevents turbulence
Conditions hydraulic fluid
Allows contaminants to settle down
Allows entrained air to escape
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Excercise - 1
Draw a hydraulic circuit to operate Bi-Directional
motor and dual acting ram.
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Solution
Reservoir
LoadLoad
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Excercis - 2
Draw a Hydraulic Circuit to operate a bi-directional motor at
different RPM (Max Pressure 2500 psi), also to supply not more
than 600 psi to a selection valve.
One of the trainees to draw it on the board.