Chapter 2

2. Chapter 2 Fluid Power Systems The Basic System

3. 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. Permission granted to reproduce for educational use only.

4. 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. Permission granted to reproduce for educational use only.

5. 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 Permission granted to reproduce for educational use only.

6. Functions of Fluid Power Systems • Fluid power systems perform five functions during operation: • Energy conversion • Fluid distribution • Fluid control • Work performance • Fluid maintenance Permission granted to reproduce for educational use only.

7. Functions of Fluid Power Systems Permission granted to reproduce for educational use only.

8. 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 Permission granted to reproduce for educational use only.

9. Basic System Components • Power unit group • Deals primarily with energy conversion • Consists of: • Prime mover • Pump or compressor • Reservoir or receiver Permission granted to reproduce for educational use only.

10. Basic System Components • Actuators group • Performs the work of the system • Consists of both cylinders and motors Permission granted to reproduce for educational use only.

11. Basic System Components • Conductors group • Conductors distribute fluid throughout the system • Consists of: • Pipes • Tubes • Hoses Permission granted to reproduce for educational use only.

12. 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 Permission granted to reproduce for educational use only.

13. 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 Permission granted to reproduce for educational use only.

14. Basic System Components • Comparisons can be made between hydraulic and pneumatic systems • System terminology and designs may vary between hydraulic and pneumatic systems Permission granted to reproduce for educational use only.

15. 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 Permission granted to reproduce for educational use only.

16. Basic System Components • Power unit • System reservoir or receiver stores system fluid • Reservoir/receiver also contributes to system temperature control and fluid cleaning Permission granted to reproduce for educational use only.

17. Actuators Cylinders are used in both hydraulic and pneumatic systems Cylinders produce linear motion Basic System Components Permission granted to reproduce for educational use only.

18. Actuators Motors are used in both hydraulic and pneumatic systems Motors produce rotary motion Basic System Components Permission granted to reproduce for educational use only.

19. 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 Permission granted to reproduce for educational use only.

20. Basic System Components • Actuators (Used with permission of CNH America LLC) Permission granted to reproduce for educational use only.

21. Basic System Components • Conductors • Pipes • Tubes • Hoses • Transmit system fluid to system components Permission granted to reproduce for educational use only.

22. 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 Permission granted to reproduce for educational use only.

23. 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 Permission granted to reproduce for educational use only.

24. Control valves Flow control valves Control fluid flow rate in a system The size of an orifice is adjusted to change flow Basic System Components Permission granted to reproduce for educational use only.

25. 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 Permission granted to reproduce for educational use only.

26. 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 Permission granted to reproduce for educational use only.

27. 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 Permission granted to reproduce for educational use only.

28. 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 Permission granted to reproduce for educational use only.

29. 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 Permission granted to reproduce for educational use only.

30. 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 Permission granted to reproduce for educational use only.

31. Review Question Fluid power systems are made up of _____ containing parts designed to perform specific tasks. component groups Permission granted to reproduce for educational use only.

32. Review Question The fluid control function of a fluid power system controls system pressure and fluid flow _____ and _____. rate; direction Permission granted to reproduce for educational use only.

33. Review Question The number and appearance of components in a fluid power system is influenced by the type of _____, application, and _____. fluid; power output Permission granted to reproduce for educational use only.

34. Review Question Fluids are distributed throughout a fluid power system by components referred to as _____. conductors Permission granted to reproduce for educational use only.

35. Review Question Fluid power system filters may be located in one or more of three typical locations. List these three locations. Intake line; working lines; return lines. Permission granted to reproduce for educational use only.

36. Review Question In the pneumatic fluid power system, after the pressurized system air has completed its work, it is exhausted to the _____. atmosphere Permission granted to reproduce for educational use only.