Chapter 2 Fluid Power Systems The Basic System 1
Objectives Explain the functions of fluid power systems. 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. 3 Objectives Describe the function of the components involved in basic fluid power systems. Describe the similarities and differences of hydraulic and pneumatic systems. Explain the operation of basic hydraulic and pneumatic systems. Goodheart-Willcox Co., Inc. 4 2
Functions of Fluid Power Systems Fluid power systems are made up of components designed to perform specific tasks These components act together to perform desired work Goodheart-Willcox Co., Inc. 5 Functions of Fluid Power Systems Fluid power systems perform five functions during operation: Energy conversion Fluid distribution Fluid control Work performance Fluid maintenance Goodheart-Willcox Co., Inc. 6 3
Functions of Fluid Power Systems Goodheart-Willcox Co., Inc. 7 Structure of Fluid Power Systems 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 Goodheart-Willcox Co., Inc. 8 4
Basic System Components Power unit group Deals primarily with energy conversion Consists of: Prime mover Pump or compressor Reservoir or receiver Goodheart-Willcox Co., Inc. 9 Basic System Components Actuators group Performs the work of the system Consists of both cylinders and motors Goodheart-Willcox Co., Inc. 10 5
Basic System Components Conductors group Conductors distribute fluid throughout the system Consists of: Pipes Tubes Hoses Goodheart-Willcox Co., Inc. 11 Basic System Components Control valves group Controls fluid pressure, flow direction, and flow rate Three groups of valves: Directional control valves Pressure control valves Flow control valves Goodheart-Willcox Co., Inc. 12 6
Basic System Components Fluid maintenance group Maintains system fluid by removing dirt, moisture, and excessive heat Filters and other devices are used to perform these functions Goodheart-Willcox Co., Inc. 13 Basic System Components Comparisons can be made between hydraulic and pneumatic systems System terminology and designs may vary between hydraulic and pneumatic systems Goodheart-Willcox Co., Inc. 14 7
Basic System Components 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 Goodheart-Willcox Co., Inc. 15 Basic System Components Power unit System reservoir or receiver stores system fluid Reservoir/receiver also contributes to system temperature control and fluid cleaning Goodheart-Willcox Co., Inc. 16 8
Basic System Components Actuators Cylinders are used in both hydraulic and pneumatic systems Cylinders produce linear motion Goodheart-Willcox Co., Inc. 17 Basic System Components Actuators Motors are used in both hydraulic and pneumatic systems Motors produce rotary motion Goodheart-Willcox Co., Inc. 18 9
Basic System Components Actuators Motion is created when pressurized fluid moves an internal part of the actuators from a high pressure area toward a low pressure area Goodheart-Willcox Co., Inc. 19 Basic System Components Actuators (Used with permission of CNH America LLC) Goodheart-Willcox Co., Inc. 20 10
Basic System Components Conductors Pipes Tubes Hoses Transmit system fluid to system components Goodheart-Willcox Co., Inc. 21 Basic 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 Goodheart-Willcox Co., Inc. 22 11
Basic System Components 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 Goodheart-Willcox Co., Inc. 23 Basic System Components Control valves Flow control valves Control fluid flow rate in a system The size of an orifice is adjusted to change flow Goodheart-Willcox Co., Inc. 24 12
Basic System Components Fluid maintenance devices Filters Separators Lubricators Used to remove contaminates and condition the fluid Assure effective system performance and acceptable service life Goodheart-Willcox Co., Inc. 25 Basic System Operation Hydraulic system operation 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 the directional control valve and on to the actuator System work is performed by the actuator Goodheart-Willcox Co., Inc. 26 13
Basic 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 Goodheart-Willcox Co., Inc. 27 Basic System Operation 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 Pressurized air is distributed to system workstations Goodheart-Willcox Co., Inc. 28 14
Basic System Operation Pneumatic 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 System work is performed by the actuator Goodheart-Willcox Co., Inc. 29 Basic System Operation Pneumatic system operation During system operation, flow control valves control the speed of actuator movement Air is discharged back into the atmosphere after passing through the system Goodheart-Willcox Co., Inc. 30 15
Review Question Fluid power systems are made up of containing tii parts designed dto perform specific tasks. component groups Goodheart-Willcox Co., Inc. 31 Review Question The fluid control function of a fluid power system controls system pressure and dfluid idflow and. rate; direction Goodheart-Willcox Co., Inc. 32 16
Review Question The number and appearance of components in a fluid power system is influenced by the type of, application, and. fluid; power output Goodheart-Willcox Co., Inc. 33 Review Question Fluids are distributed throughout a fluid power system by components referred dto as. conductors Goodheart-Willcox Co., Inc. 34 17
Review Question Fluid power system filters may be located in one or more of fthree typical llocations. List these three locations. Intake line; working lines; return lines. Goodheart-Willcox Co., Inc. 35 Review Question In the pneumatic fluid power system, after the pressurized system air has completed ltdits work, it is exhausted to the. atmosphere Goodheart-Willcox Co., Inc. 36 18
Glossary Actuator A component used to convert the energy in hydraulic fluid or compressed air into mechanical linear or rotary motion. Goodheart-Willcox Co., Inc. 37 Glossary Component group A group of commonly designed hydraulic or pneumatic components offered in a full range of sizes with appropriate accessories. Compressor The pneumatic system device that converts the energy input of the system prime mover into high-pressure compressed air. Goodheart-Willcox Co., Inc. 38 19
Glossary Conductor 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 rate, or actuator direction in a fluid power system. Goodheart-Willcox Co., Inc. 39 Glossary Cylinder The common term for linear actuators t 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, and stop system actuators. Goodheart-Willcox Co., Inc. 40 20
Glossary 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. Goodheart-Willcox Co., Inc. 41 Glossary Flow control valve A component designed dto provide control of the rate of flow of air or liquid in hydraulic and pneumatic systems. Goodheart-Willcox Co., Inc. 42 21
Glossary 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 component of the FRL unit located at the workstation. Goodheart-Willcox Co., Inc. 43 Glossary Motor An actuator t that tprimarily il 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 in fluid power systems. Goodheart-Willcox Co., Inc. 44 22
Glossary Power 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. Goodheart-Willcox Co., Inc. 45 Glossary 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. Goodheart-Willcox Co., Inc. 46 23
Glossary 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. Goodheart-Willcox Co., Inc. 47 Glossary Prime mover The source of energy for any fluid power system. Commonly used prime movers are electric motors and internal combustion engines. Goodheart-Willcox Co., Inc. 48 24
Glossary Pump 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 the compressor, that stores and assists in conditioning compressed air. Goodheart-Willcox Co., Inc. 49 Glossary Reservoir A component in a hydraulic system that holds the system fluid not currently in use in the pump, control components, actuators, and lines. Goodheart-Willcox Co., Inc. 50 25
Glossary 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. Goodheart-Willcox Co., Inc. 51 Glossary System function The tasks completed ltdby the operation of a fluid flid 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 component parts, such as the barrel of cylinders. Goodheart-Willcox Co., Inc. 52 26