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Fluid Power Fundamentals Flashcards

1
Q

Fluid

A

A substance capable of flowing - liquid or gas

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2
Q

Fluid Power

A

Using fluid to do work

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3
Q

Pneumatics

A

Operated by air

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4
Q

Hydraulics

A

Operated by liquid

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5
Q

Hydrostatics

A

Energy of a liquid at rest

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6
Q

Hydrokinetics

A

Energy of a liquid in motion

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7
Q

Hydromechanics

A

Hydrostatics and Hydrokinetics

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8
Q

Hydraulic Advantages (9)

A 
Infinite control of speed and pressure
Robust equipment
Change direction quickly
Self-Lubricating
Transmits large forces
Plumbing at tighter angles
Good power to weight ration
Leaks easily detected
Fluid is recirculated in system
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9
Q

Pneumatic Advantages (9)

A 
Equipment light weight
No need for return lines
Economical
No storage facility requirements
High speed
Components are relatively cheap
Safe in explosive enivironment
Environmentally friendly
Little effect from temperature up to 120C
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10
Q

Energy Forms (7)

A 
Mechanical/Electrical
Heat
Light
Sound
Hydraulic/Pneumatic
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11
Q

Energy States

A

Potential - Stored

Kinetic - In motion

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12
Q

Mass

A

Amount of matter in an object
Symbol: m
SI Unit: kg

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13
Q

Force

A

An influence capable of producing a change in motion
Symbol: F
SI Unit: N (Newton)

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14
Q

Work

A

Force applied over a distance
Symbol: W
SI Unit: J (Joule)

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15
Q

Energy

A

A body’s ability to do work
Symbol: E
SI Unit: J (Joule)

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16
Q

Torque

A

Rotary or turning effect
Symbol: T
SI Unit: Nm (Newton meter)

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17
Q

Power

A

Work divided by time
Symbol: P
SI Unit: W (Watt)

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18
Q

PSI

A

Imperial standard for pressure
Pounds per square inch
14.7 PSI = 1 BAR

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19
Q

Pressure

A

The result of resistance to flow
Symbol: p
SI Unit: Pa (Pascal)

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20
Q

F = PA

A

Pressure Calculation Triangle:
Force in Deca Newtons
Pressure in Bar
Area in cm2

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21
Q

Pascal’s Law (SA)

A

Pressure applied to a static and confined fluid will be transmitted undiminished in all directions, and acts with equal force on equal areas and at right angles to them.

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22
Q

Force through a solid

A

In a straight line

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23
Q

Force through a liquid

A

In every direction equal to area

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24
Q

Flow Law

A

As cross sectional path increases:
Viscosity Decreases
Pressure Increases

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25
Q

Laminar Flow

A

Flow without turbulence

Caused by straight pipes

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26
Q

Turbulent Flow

A

Flow with turbulence
Caused by:
Bent Pipes
To high velocity

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27
Q

Viscosity (2)

A

Measure of a fluids internal resistance to flow

Generally: As temperature increases, viscosity decreases

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28
Q

Viscosity Index

A

Measure of change in viscosity due to temperature

High number = Less change

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29
Q

Hydraulic Fluid Properties (8)

A 
Compatibility with different materials
Low compressibility
Little expansion due to temperature
Little formation of foam
High boiling pint, low steam pressure
Non hygroscopic - Doesn't absorb water
Fire resistance
Good protection against corrosion
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30
Q

Hydraulic Fluid Types (6)

A 
Petroleum based
Fire resistant
Oil in water emulsion
Water in oil emulsion
Water glycol
Synthetic
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31
Q

Drive Motor

A

Also Called Prime Mover
Commonly Electric Motor
Turns electrical energy into mechanical energy

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32
Q

Cooler/Heat Exchange (3)

A

Maintains constant temperature
Water cooled
Air cooled

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33
Q

Reservoir

A

Tank

Should contain 3x maximum pump displacement

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34
Q

Purpose of Reservoir (6)

A

Store oil
Provide cooling for returning oil
Allow atmospheric pressure to assist moving oil into pump
Separate contamination from oil
Separation of aeration from oil
Allow mounting of power pack components and associated equipment

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35
Q

Baffle Plate

A

Separates returning oil from suction line to allow reservoir effects to take place

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36
Q

Fluid Level Indicator

A

Sight guage, visual

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37
Q

Fluid Level Sensor

A

Float switch, electrical

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38
Q

Filter Breather

A

Filters atmospheric air into system

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39
Q

Pipes (3)

A

Welded seam
Rigid
Not bendable

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40
Q

Tubing (3)

A

Extruded seam
Rigid and semi-rigid
Bendable

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41
Q

Flexible Hoses (3)

A

Used where there is:
Moving parts
Vibration
Can be skived or non-skived (reinforced)

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42
Q

Fittings (3)

A

Flared - Reusable
Compression - Non-reusable (Swaged)
O-ring - reusable

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43
Q

Fluid Conductors (3)

A

Pipes
Tubing
Flexible Hoses

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44
Q

Pilot Line

A

To control the operation of a component

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45
Q

Drain Line

A

To return leakage oil to tank

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46
Q

Purpose of Hydraulic Pump

A

Convert mechanical energy from drive motor to hydraulic energy

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47
Q

Hydraulic Pump Info (4)

A

Pumping action is the same for all pumps
Increased volume @ suction side
Decreased volume @ pressure side
Industrial hydraulic systems use positive displacement pumps

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48
Q

Pumps are for?

A

FLOW

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49
Q

Hydraulic Pump Types (3)

A

Gear
Piston
Vane

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50
Q

Hydraulic Pumps - Gear (5)

A

Worm (Screw)
External
Internal - Crescent, Gerotor

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51
Q

Hydraulic Pumps - Piston (3)

A

Axial Inline
Bent Axial
Radial

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52
Q

Hydraulic Pumps - Vane (2)

A

Unbalanced - single

Balanced - double

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53
Q

Atmospheric Pressure

A

The weight of air exerting a pressure on earth

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54
Q

Pressure Scales (3)

A

Gauge - Begins at atmospheric pressure
Absolute - Begins at 0 pressure
Vacuum - Any pressure less then 1 atmosphere
(Measured in inHg - inches of mercury)

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55
Q

Cavitaion Definition/Effects (3)

A

Formation and collapse of gaseous cavities within a liquid
Lowers lubrication
Destroys metal surfaces

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56
Q

Causes of Cavitation (5)

A 
Blocked strainer
Blocked breather
Incorrect oil
Intake line too small
Viscosity of oil too high
(Not enough oil in pump)
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57
Q

Entrained Air

A

Air at atmospheric pressure entering system

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58
Q

Causes of Entrained Air (3)

A

Loose/cracked pipes/fittings
Worn shaft seal
Reservoir levels too low
(Air in system)

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59
Q

Actuator Use/Types (3)

A

Converts fluid energy to mechanical energy

Linear (straight line) or rotary (rotating)

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60
Q

Rotary Actuator Name/Info (6)

A 
Hydraulic motor
Instant reversing of shaft
Stall for indefinite periods, no damage
Torque control through operating speed
Dynamic breaking easily accomplished
Good power to weight ratio
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61
Q

Control Valve Types (4)

A

DCV - directional control valve
Flow
Pressure
Non return (check)

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62
Q

DCV Meaning and Use (4)

A

Directional Control Valve
Controls direction of flow
Isolates different parts of a circuit
Controls actuator motion

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63
Q

DCV Identification (5)

A 
Ports
Positions
Configuration
Method of actuating
Method of de-actuating
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64
Q

4/3 DCV Center Positions (4)

A

Open Center - Uninhibited movement
Float Center - Free movement
Closed Center - No movement
Tandem Center - No movement - Less pressure

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65
Q

Methods of Actuation - Manual (4)

A

General
Pedal
Lever
Push Button - No electricity

66
Q

Methods of Actuation - Mechanical (3)

A

General
Cam/Roller
One way trip

67
Q

Methods of Actuation - Electrical

68
Q

Methods of Actuation - Pilot (3)

A

Hydraulic direct/indirect
Pneumatic direct/indirect
Solenoid Pilot - master/slave

69
Q

Methods of Actuation (4)

A

Manual
Mechanical
Electrical
Pilot

70
Q

Methods of De-actuation (3)

A

Springs - Return or centered
Detent - Number of notches
Memory - 2DCV No springs/detents
Either dual pilot or solenoid

71
Q

Non Return Valve (Check) Use

A

Stop flow one way, allow the other

72
Q

Pilot Operated Check Valve

A

Acts like normal check valve

With pilot signal, can flow backwards

73
Q

Gate Valve

A

Two way gate, on/off

74
Q

Shuttle Valve

A

Logical “or”

75
Q

Flow Control Valves Names/Use (5)

A

Reduces flow rate from pump to actuator

Also called: orifice, restrictor, throttle, choke

76
Q

What Effects Flow (3)

A

Pressure - Greater the difference across orifice, more flow
Orifice - Size of orifice changes flow
Temperature - Changes liquid viscosity

77
Q

Fixed Orifice

A

Reduced opening of unadjustable size

78
Q

Variable Orifice

A

Reduced opening of adjustable size

79
Q

Temperature Compensated Flow Control Valve

A

Orifice size varied by temperature

80
Q

Pressure Compensated Flow Control Valve Types (2)

A

Either restricter or bypass

81
Q

Methods of Flow Control (4)

A

Variable pump output - Change at pump, varies whole system
Meter in - Controls amount of fluid going in
Meter out - Controls amount of fluid going out
Bleed off - Split some flow back to tank, very inaccurate

82
Q

Pressure Control Valve Use

A

Controlling force

83
Q

Pressure Control Valve Types

A

Hydraulic - Pneumatic
Relief - Limiting
Sequencing
Reducing - Regulator

84
Q

Relief/Limiting Valve

A

Normally closed
Protects from overpressurisation
Has cracking/full flow pressure

85
Q

Pilot Operated Relief Valve

A

For high flow rate
Has two parts
Pilot is like direct relief valve, when activated opens main valve for more flow

86
Q

Sequencing Valve

A

Normally closed
Causes the operation of 2 or more actuators to happen in order
Has the check valve

87
Q

Reducing/Regulator Valve

A

Normally open

Controls the force by reducing orifice size

88
Q

Filtration

A

Removal of contaminants from fluid

89
Q

Effects of Dirt (3)

A

Plugs small orifices
Interferes with cooling
Interferes with lubrication

90
Q

Sources of Dirt (3)

A

Built in during fabrication
Generated from wear and tear
Added during maintenance from environment

91
Q

Filter Element Materials (8)

A

Paper, Cellulose, Felt
Glass Fiber, Plastics
Ceramics, Stainless Steel
Sintered powders of metals

92
Q

Types of Filter (2)

A

Surface - One layer

Depth - Appreciable thickness

93
Q

Location of Filters (4)

A

Sump strainer
Suction line
Pressure line
Return line

94
Q

Use of Seals (3)

A

Prevent loss of fluid
Keep contamination out
Allowed controlled leakage for lubrication

95
Q

Positive Seal

A

No leakage

96
Q

Non-positive Seal

A

Controlled leakage

97
Q

Static Seal

A

Seal between two stationary parts

98
Q

Dynamic Seal

A

Seal between two parts that move relative to each other

99
Q

Types of Seal (8)

A

O-Ring, Backup, T-Ring
Lip, Cup, Piston Ring
Compression Ring, Gasket

100
Q

Seal Materials (6)

A 
Nitrile (Buna N)
Viton (Synthetic oils, high temp)
Neoprene (Cold temp)
Plastics (Teflon)
Synthetic Rubber (Elastomers)
Cast Iron
101
Q

Incorrect Installation of Seal Causes (4)

A

Vibration
External Leakage
Wear
Contamination Ingression

102
Q

Hydraulic Transducers

A

Takes a measurement, turns into data

103
Q

Pressure Gauges (2)

A

Bourdon Tube - Curved tube

Plunger - Plunger and spring

104
Q

Pressure Switches (2)

A

Bourdon Tube - connected to switch

Piston - connected to switch

105
Q

Pressure Transducers - Differential Pressure Cell

A

Compares two different pressures

106
Q

Flow meter

A

Determines rate of flow

Like ameter - Physically in system

107
Q

Temperature Transducers Types (2)

A

Thermocouple, thermister

108
Q

Proximity Transducer Use/Types (3)

A

Detects when objects get close to sensor without touching

Inductive or capacitive

109
Q

Proximity Transducer - Inductive

A

Proximity to “core” changes current

OR magnet approaching high turn ratio inductor will produce voltage relative to distance

110
Q

Proximity Transducer - Capasitive

A

Distance between plates

or Change in dielectirc

111
Q

LVDT (2)

A

Linear Variable Differential Transformer

Inductive Positional Transducer

112
Q

Limit/Cut-out Switches

A

Mechanical action

113
Q

Common Hydraulic Injuries (3)

A

Burns
Cuts/Bruises
Injection of Fluid

114
Q

Hydraulic System Procedures (3)

A

Start
Stop
Emergency Stop

115
Q

Hydraulic Precautions - Easy (7)

A 
Fix oil leaks
Correct PPE
Mop up excess oil
Put oil soaked cloths in bin
Wipe oil from tools after use
Depressurize to work
Support Heavy Loads
116
Q

Hydraulic Precautions - Harder (8)

A

Clean up petroleum based fluids
All open oil ports plugged
Know type/location of extinguisher
Ensure over pressure protection equipment serviceable
Ensure hydraulically/electrically isolated
Handle components with extreme care
Consult manufacturers specifications when re-assembling
Ensure SDS held and followed

117
Q

Parts of Pneumatic System (8)

A

Drive Motor, Valves
Compressor, Actuator
Air Service Unit, Plumbing
Receiver, Cooler/Heat Exchanger

118
Q

Compressor Types (2)

A

Displacement

Dynamic

119
Q

Compressors - Displacement (7)

A 
Reciprocating:
    Piston
    Diaphragm
Rotary:
    Screw
    Vane
    Roots
120
Q

Compressors - Dynamic (2)

A

Also called turbo/centrifugal
Radial flow
Axial flow

121
Q

Air Receiver

A

For storing potential energy only

122
Q

Pneumatic Actuators

A

Generally lighter construction

Linear Piston same as hydraulic

123
Q

Diaphragm Cylinder

A

Less mass, flexes diaphragm

Increases speed

124
Q

Rodless Cylinder

A

Rod fixed, cylinder body moves

Coupled together, usually magnetically

125
Q

Rotary Actuator

A

Air motor

Reverse of compressor

126
Q

Pneumatic DCV

A

Has little triangle to show exhaust to atmosphere

Can be labeled R/S if used elsewhere

127
Q

Pneumatic Check Valves (2)

A

Double Cut-off - Logic “and” function

Quick Exhaust - Opens check valve to quickly exhaust

128
Q

Pneumatic Pressure Control Valves (3)

A

Pneumatic - Hydraulic
Limiting - Relief
Sequencing
Regulator - Reducing

129
Q

Air Preparation Qualities (6)

A 
Pressure
Quantity
Water Content
Solid Content
Oil Content
Sterility
130
Q

Intake Filter Location

A

At intake of compressor

131
Q

Air Line Filter Location

A

Directly after cooler

132
Q

Filter Silencer

A

Silences exhaust sound using baffles

Filters contaminants

133
Q

Effects of Moisture in System (6)

A

Lack of lubrication, wear
Corrosion, Faulty operation of components
Product defects, Safety hazards

134
Q

Air Dryer Types (3)

A

Refrigerated - Reduces temperature to condense water
Adsorption - Most common, desiccant adsorbs water
(Adsorb meas hold to surface)
Absorption - Chemical process, expensive

135
Q

Air Service Unit

A

Also called FLR (Filter, regulator, lubricator)

Ensures specified quality of compressed air

136
Q

FLR

A

Filter, regulator, lubricator

Also called air service unit

137
Q

Lubricator

A

Ideally air is clean, but sometimes lubrication is required

Fitted prior to machine working elements

138
Q

Purpose of Lubrication (5)

A 
Seal lubrication
Unhindered movement of components
Prevention of wear
Reduces friction
Reduces corrosion
139
Q

Types of Lubricators (2)

A

Oil fog

Oil mist

140
Q

Lubrication - Oil Fog

A

Course droplets
Passes through venturi
Mounted as close as possible to equipment

141
Q

Lubrication - Oil Mist

A

Very fine droplets
Passes through deflector
Mounted above/below workstation

142
Q

Pneumatic Safety Part 1 (5)

A 
Over pressure safety valves fitted
System pressure ratings followed
Receivers monitored and checked
Receiver valves correct size/rating
Receivers marked with test pressure, test date
143
Q

Pneumatic Safety Part 2 (4)

A

Main airline shutoff valve for emergency venting
All pressure vented before maintenance, isolate parts
Compressed air not used on cloths or people
System vented/shutdown, air supply isolated for maintenance

144
Q

Fault Finding 7 Steps (In order)

A
  1. Know the system
  2. Ask the operator
  3. Operate the machine
  4. Inspect the machine
  5. List possible causes
  6. Reach a conclusion
  7. Test your conclusion
145
Q

Types of Maintenance (2)

A

Preventative - Before it breaks

Corrective - When broken

146
Q

Hydraulic Weekly Maintenance (5)

A 
Check:
Oil level
Oil leaks
Guards
Valves
Plumbing
147
Q

Pneumatic Weekly Maintenance (5)

A 
Check:
Air leaks
Compressor
Receiver
Actuator
Guards
148
Q

Pneumatic Daily Maintenance (2)

A

Drain moisture from receiver

Check compressor oil levels

149
Q

Prior to Installation (6)

A 
Check correct parts
Read manufacturers instructions
Ensure layout drawings are up to date
Compare parts, ensure they fit
Don't remove covers until ready to install
Ensure you have the right tools
150
Q

During Installation (3)

A

Mounting Position - Clear of obstructions
Mounting Method - Don’t over tighten
The Circuit - Check it matches drawings

151
Q

Accumulator

A

Stores pressurized oil in system
Treated as pressurized vessel
Power required to get oil out

152
Q

Types of Accumulators (3)

A

Hydro-pneumatic - Pressurized with gas, most common
Weight loaded
Spring loaded

153
Q

Hydro-pneumatic Types and Gas (4)

A 
Uses Nitrogen, because inert
3 types:
Bladder
Membrane (Diaphragm)
Piston
154
Q

Main Function of Accumulator (2)

A

Stores energy

Dampens shocks

155
Q

Uses of Accumulator (7)

A

Fluid reserve, compensation of leaking oil
Emergency operation, maintaining constant pressure
Balance of forces, compensation of flow
Damping of mechanical and pressure shocks

156
Q

Pre-charge

A

Gas pressure in accumulator when drained of all oil

Higher pre-charge, less oil will be stored

157
Q

Servo Valve

A

Provides closed loop flow in response to signal

Small electrical signal, large hydraulic output

158
Q

Servo Valve Parts (4)

A

Torque motor
Flapper jet valve
Spool valve
Feedback

159
Q

Servo Valve - Torque Motor

A

Produces torque from current
Moves an armature
Flapper is attached to armature

160
Q

Servo Valve - Flapper Jet Valve

A

Controls fluid through valve, creating pilot signal for spool

161
Q

Servo Valve - Spool Valve

A

Pilot signal moves spool

Spool acts like DCV

162
Q

Servo Valve - Feedback (3)

A

3 types:
Mechanical - Feedback spring attached to main spool, moved by spool movements
Barometric - Pilot pressure against spring centering pressure, balances the force
Electrical - Uses LVDT attached to spool

Net 02 (1 decks)

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