chapter 2 fluid power systems - pbworks · pdf file7 basic system components fluid maintenance...

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Chapter 2Chapter 2

The Basic SystemThe Basic System

Fluid Power SystemsFluid Power Systems

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ObjectivesObjectives

Explain the functions of fluid power p psystems. Identify the basic structure of fluid power

systems. List the basic component groups involved in

the structure of fluid power systems.

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.3

the structure of fluid power systems.

ObjectivesObjectives

Describe the function of the components pinvolved in basic fluid power systems.

Describe the similarities and differences of hydraulic and pneumatic systems.

Explain the operation of basic hydraulic and


pneumatic systems.

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Functions of Fluid Power Functions of Fluid Power Systems Systems

Fluid power systems are made up of Fluid power systems are made up of components designed to perform specific tasks

These components act together to perform desired work


Functions of Fluid Power Functions of Fluid Power SystemsSystems

Fluid power systems perform five functions d i tiduring operation:– Energy conversion

– Fluid distribution

– Fluid control

– Work performance


Work performance

– Fluid maintenance

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Functions of Fluid Power Functions of Fluid Power SystemsSystems


Structure of Fluid Power Structure of Fluid Power Systems Systems

Fluid power systems are structured using Fluid power systems are structured using component groups that perform specific system functions:– Power unit group

– Actuators group


– Conductors group

– Control valves group

– Fluid maintenance group

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Basic System Components Basic System Components

Power unit group– Deals primarily with energy conversion

– Consists of:• Prime mover

• Pump or compressor

• Reservoir or receiver


Basic System ComponentsBasic System Components

Actuators group– Performs the work of the system

– Consists of both cylinders and motors


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Conductors group– Conductors distribute fluid

throughout the system

– Consists of:• Pipes

• Tubes


• Hoses


Control valves group– Controls fluid pressure, flow direction, and flow

rate

– Three groups of valves:• Directional control valves

• Pressure control valves


• Flow control valves

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Fluid maintenance group– Maintains system fluid by removing dirt, moisture,

and excessive heat

– Filters and other devices are used to perform these functions



Comparisons can be made between Comparisons can be made between hydraulic and pneumatic systems

System terminology and designs may vary between hydraulic and pneumatic systems


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Power unit Power unit– Electric motors and internal combustion

engines are most often the prime movers

– The pump or compressor produces the fluid flow


– Fluid flow is created by internal pressure differences

– Fluid flow transmits energy throughout the system


Power unit– System reservoir or receiver stores system fluid

– Reservoir/receiver also contributes to system temperature control and fluid cleaning


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ActuatorsC li d d i– Cylinders are used in both hydraulic and pneumatic systems

– Cylinders produce linear motion



ActuatorsM t d i b th– Motors are used in both hydraulic and pneumatic systems

– Motors produce rotary motion


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Actuators– Motion is created when pressurized fluid moves an

internal part of the actuators from a high pressure area toward a low pressure area



Actuators


(Used with permission of CNH America LLC)

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Conductors– Pipes

– Tubes

– Hoses

– Transmit system fluid to system components



Control valves– Directional control valves

• Vary the direction of movement of cylinders and motors

• Change fluid flow paths to and from the actuators


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Control valves– Pressure control valves

• Control pressure in a fluid power system

• Restrict fluid flow into a part of the system

• Allow fluid to return to a low pressure area after a desired pressure is reached



Control valvesFl t l l– Flow control valves

• Control fluid flow rate in a system

• The size of an orifice is adjusted to change flow


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Fluid maintenance devices– Filters

– Separators

– Lubricators

– Used to remove contaminates and condition the fluid


– Assure effective system performance and acceptable service life

Basic System Operation Basic System Operation

Hydraulic system operationy y p– Movement of oil originates at the pump

– Low pressure at the pump inlet causes oil to pass through a filter as it flows from the reservoir into the pump

High pressure at the pump outlet forces oil to


– High pressure at the pump outlet forces oil to the directional control valve and on to the actuator

– System work is performed by the actuator

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Basic System OperationBasic System Operation

Hydraulic system operation– Pressure control valves limit pressure in the system

– Flow control valves control the speed of actuator movement

– Oil is returned to the reservoir to be recirculated through the system


g y


Pneumatic system operation– Movement of air begins at the compressor– As air moves into the system from the atmosphere,

it is:• Filtered• Compressed• Stored in the receiver under pressure


Stored in the receiver under pressure

– Pressurized air is distributed to system workstations

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Pneumatic system operationPneumatic system operation– At the workstation:

• A pressure regulator sets working pressure

• A filter and lubricator provide final conditioning

– Air then moves through a directional control valve and on to an actuator


valve and on to an actuator

– System work is performed by the actuator


Pneumatic system operationD i t ti fl t l l– During system operation, flow control valves control the speed of actuator movement

– Air is discharged back into the atmosphere after passing through the system


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Review QuestionReview Question

Fluid power systems are made up of _____ t i i t d i d t f ificontaining parts designed to perform specific

tasks.

component groups



The fluid control function of a fluid power t t l t d fl id flsystem controls system pressure and fluid flow

_____ and _____.

rate; direction


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The number and appearance of components in fl id t i i fl d b th ta fluid power system is influenced by the type

of _____, application, and _____.

fluid; power output



Fluids are distributed throughout a fluid power t b t f d tsystem by components referred to as _____.

conductors


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Fluid power system filters may be located in f th t i l l ti Li tone or more of three typical locations. List

these three locations.

Intake line; working lines; return lines.



In the pneumatic fluid power system, after the i d t i h l t d it kpressurized system air has completed its work,

it is exhausted to the _____.

atmosphere


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GlossaryGlossary

Actuator– A component used to convert the energy in

hydraulic fluid or compressed air into mechanical linear or rotary motion.


GlossaryGlossary

Component group– A group of commonly designed hydraulic or

pneumatic components offered in a full range of sizes with appropriate accessories.

CompressorThe pneumatic system device that converts the


– The pneumatic system device that converts the energy input of the system prime mover into high-pressure compressed air.

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GlossaryGlossary

ConductorThe element used in fluid power systems to allow– The element used in fluid power systems to allow the movement of hydraulic fluid or compressed air from component to component. Hose, pipe, and tubing are the most common fluid power conductors.

Control valve– Any valve designed to control fluid pressure flow


– Any valve designed to control fluid pressure, flow rate, or actuator direction in a fluid power system.

GlossaryGlossary

CylinderTh t f li t t d t– The common term for linear actuators used to generate movement and force in fluid power systems.

Directional control valve– Hydraulic and pneumatic control valves that direct

fluid flow to start control direction of movement


fluid flow to start, control direction of movement, and stop system actuators.

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GlossaryGlossary

Filter– A fluid power component that is used to remove

solid contaminants from both air and liquid. The term is often used to designate the complete component including the filter element, case, and mounting hardware.


GlossaryGlossary

Flow control valveA t d i d t id t l f th t– A component designed to provide control of the rate of flow of air or liquid in hydraulic and pneumatic systems.


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GlossaryGlossary

Hose– A flexible conductor for carrying hydraulic fluid or

compressed air to actuators.

Lubricator– A device designed to apply a lubricant to a bearing

surface. In pneumatic systems, the lubricator is a


p ycomponent of the FRL unit located at the workstation.

GlossaryGlossary

MotorA t t th t i il d ti– An actuator that primarily produces continuous, rotary motion. These components may be powered by electricity, hydraulics, or pneumatics.

Pipe– Rigid tube made from steel with adequate wall

thickness to be threaded Often used as a conductor


thickness to be threaded. Often used as a conductor in fluid power systems.

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GlossaryGlossary

Power unitPower unit– The unit in a hydraulic system that provides

energy for the system, moves fluid through the system, provides a safe maximum limit of system pressure, and maintains desired system temperature and fluid cleanliness.


GlossaryGlossary

Pressure control valves– Control valves in a fluid power circuit designed to

protect the system from damage from excessive pressure, provide motion control, and protect operators from unexpected actuator movement.


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GlossaryGlossary

Pressure regulator– A pneumatic system component used to

control air pressure at the system workstations. The valve maintains a constant, reduced pressure for use by tools and equipment operated at the station.


GlossaryGlossary

Prime mover– The source of energy for any fluid power system.

Commonly used prime movers are electric motors and internal combustion engines.


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Pump

GlossaryGlossary

– A hydraulic component turned by the prime mover that produces fluid flow, which transmits energy through the system.

Receiver– A tank in a pneumatic system, located close to


A tank in a pneumatic system, located close to the compressor, that stores and assists in conditioning compressed air.

GlossaryGlossary

Reservoir– A component in a hydraulic system that holds

the system fluid not currently in use in the pump, control components, actuators, and lines.


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GlossaryGlossary

Separator– A component, located in the compressor station

area of a pneumatic system, that is designed to remove condensed water from the compressed air. The unit is often teamed with an aftercooler to optimize moisture removal.


GlossaryGlossary

System functionTh t k l t d b th ti f fl id– The tasks completed by the operation of a fluid power system.

Tube– Generally defined as a long, cylindrical body with

an open center. Tubes are used extensively in the fluid power field as fluid conductors and as


fluid power field as fluid conductors and as component parts, such as the barrel of cylinders.

chapter 2 fluid power systems - pbworks · pdf file7 basic system components fluid maintenance...

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