1. Fluid Power Control

2. Module:03 ~ Hydraulic SYSTEM COMPONENTS
FLUID POWER
Module:03 ~ Hydraulic SYSTEM COMPONENTS
Sources of Hydraulic Power
Construction and working of pumps – Variable displacement pumps
Actuators: Linear hydraulic actuators
Single acting and Double acting cylinders
Fluid motors.
Control Components:
Direction control valve (DCV)
Flow control valves (FCV)
Pressure Control Valves (PCV)
Electrical control -- solenoid valves. Relays, Accumulators and Intensifiers.

3. Directional control valves ~
FLUID POWER
Hydraulic Valves
There are basically three types of valves employed in hydraulic systems:
Directional control valves ~
Determines the path through which a fluid transverses a given circuit.
2. Flow control valves ~
Absorbers shock and smoothes out pressure surges
3. Pressure control valves ~
Protects the system against overpressure

4. FLUID POWER
Hydraulic Valves
Directional control valves ~ determines the path through which a fluid transverses a given circuit.
 To start, stop, accelerate, decelerate and change the direction of motion of a hydraulic actuator receiving some external signal (mechanical / electrical, fluid pilot signal.
 To permit the free flow from the pump to the reservoir at low pressure when the pump’s delivery is not needed into the system.
 To isolate certain branch of a circuit.

5.  Number switching positions.
FLUID POWER
Hydraulic Valves
Directional control valves ~ Classification based on design characteristics:
 Number of connecting ports / ways.
 Number switching positions.
 Method of valve actuation to move into alternate position.

6. Direction Control Valves: ~
FLUID POWER
Hydraulic Valves
Direction Control Valves: ~
These control valves contain ports that are external openings for the fluid to enter and leave.
The number of ports is usually identified by the term ‘WAY’.
By various ‘POSITIONS’ of the lever / spool ports can be connected internally with each other.

7. Direction Control Valves:~ Check valves
FLUID POWER
Hydraulic Valves
Direction Control Valves:~ Check valves

8. Direction Control Valves:~ Pilot operated Check valves
FLUID POWER
Hydraulic Valves
Direction Control Valves:~ Pilot operated Check valves

9. Direction Control Valves:~
FLUID POWER
Hydraulic Valves
Direction Control Valves:~

10. Hydraulic Valves DCV:~ SPOOL type valve FLUID POWER
 Points to discuss: What is a spool? / How does it function?

11. DCV:~ 2/2-Way DCV (SPOOL type)
FLUID POWER
Hydraulic Valves
DCV:~ 2/2-Way DCV (SPOOL type)
Two-way two-position normally closed DCV

12. Each switching position is shown by a square.
FLUID POWER
Hydraulic Valves
DCV ~ How to represent?
Each switching position is shown by a square.
Flow direction is indicated by arrows.
Blocked ports are shown by Hz lines.

13. DCV:~ 2/2-Way DCV (SPOOL type)
FLUID POWER
Hydraulic Valves
DCV:~ 2/2-Way DCV (SPOOL type) P A
Two-way two-position normally closed DCV

14. DCV:~ 2/2-Way DCV (Normally open)
FLUID POWER
Hydraulic Valves
DCV:~ 2/2-Way DCV (Normally open)
Two-position–two- way normally open DCV

15. A pair of two-way valves is used to fill and drain a vessel.
FLUID POWER
Hydraulic Valves
DCV:~
Application of 2/2-Way DCV
***
A pair of two-way valves is used to fill and drain a vessel. **

16. FLUID POWER
Hydraulic Valves
DCV:~ 3-Way DCV
3/2 DCV

17. FLUID POWER
Hydraulic Valves
DCV:~ 3-Way DCV
3/2 DCV
3/3 DCV

18. DCV:~ 3/3 DCV // Application
FLUID POWER
Hydraulic Valves
DCV:~ 3/3 DCV // Application
(a) Fill
(b) Hold
(c) drain

19. Application of 3/3 DCV– Controlling a Single Acting Cylinder
FLUID POWER
Hydraulic VALVES - DCV:~ 3/3 DCV
Application of 3/3 DCV– Controlling a Single Acting Cylinder

20. What if we have a Double Acting Cylinder?
FLUID POWER
Hydraulic Valves ~ DCV
Application of 3/2 DCV
What if we have a Double Acting Cylinder?

21. Hydraulic Valves ~ 4way DCV
FLUID POWER
Hydraulic Valves ~ 4way DCV

22. Hydraulic Valves ~ 4/2 DCV
FLUID POWER
Hydraulic Valves ~ 4/2 DCV
 Points to discuss: Spool position; One Tank port in graphic symbol;
..\video\Edited\Learn hydraulics - 4_2 Directional control valve.mp4

23. Application of 4/2 DCV ~ Control of Double Acting Cylinder
FLUID POWER
HYDRAULIC VALVES ~ 4/2 DCV
Application of 4/2 DCV ~ Control of Double Acting Cylinder

24. Application of 4/2 DCV ~ Control of Bi-directional Motor
FLUID POWER
HYDRAULIC VALVES ~ 4/2 DCV
Application of 4/2 DCV ~ Control of Bi-directional Motor

25. HYDRAULIC VALVES ~ 4/2 DCV
FLUID POWER
HYDRAULIC VALVES ~ 4/2 DCV
~ Application of 4/2 DCV ~
Control of Double Acting Cylinder
Control of Bi-directional Motor
This design is sometimes IMPRACTICAL !!!
Because it continuously send pump flow and pressure to the actuator from one direction or the other.

26. Hydraulic Valves ~ 4way DCV DCV:~ 4/3 DCV
FLUID POWER
Hydraulic Valves ~ 4way DCV
DCV:~ 4/3 DCV
Closed neutral.
Tandem neutral.
Float neutral.
Open neutral.
 Points to discuss: Why 3 position?; Types; Operation;

27. Hydraulic Valves ~ 4way DCV DCV:~ 4/3 DCV
FLUID POWER
Hydraulic Valves ~ 4way DCV
DCV:~ 4/3 DCV
Closed neutral for controlling a double-acting cylinder:

28. Hydraulic Valves ~ 4way DCV DCV:~ 4/3 DCV
FLUID POWER
Hydraulic Valves ~ 4way DCV
DCV:~ 4/3 DCV
Tandem neutral for controlling a double-acting cylinder:

29. Hydraulic Valves ~ 4way DCV DCV:~ 4/3 DCV
FLUID POWER
Hydraulic Valves ~ 4way DCV
DCV:~ 4/3 DCV
Float neutral for controlling a bidirectional motor:

30. Hydraulic Valves ~ 4way DCV DCV:~ 4/3 DCV
FLUID POWER
Hydraulic Valves ~ 4way DCV
DCV:~ 4/3 DCV
Open neutral for controlling a Double Acting Cylinder:

31. DCV:~ Graphic symbols and Labeling
FLUID POWER
Hydraulic Valves
DCV:~ Graphic symbols and Labeling
Switching position is shown by a Square / Envelope
Flow Paths are indicated by arrows
Blocked position shown by horizontal lines
Ports are labeled for one envelope
It is usually done in envelope representing the neutral / un-actuated position.

32. 4/3 Direction Control Valves With various Neutral Positions
FLUID POWER
Hydraulic Valves
DCV:~ Graphic symbols and Labeling
4/3 Direction Control Valves With various Neutral Positions
***

33. DCV:~ Graphic symbols and Labeling
FLUID POWER
Hydraulic Valves
DCV:~ Graphic symbols and Labeling
ACTUATING DEVICES
Manually Operated / Actuated by lever
Spring Centered / When un-actuated, it returns to center position by spring
force.
Represents spring offset/return; When un-actuated return to labeled envelope.
They click into position and hold that position indefinitely. Detented valves have no normal position.

34. DCV:~ Graphic symbols and Labeling
FLUID POWER
Hydraulic Valves
DCV:~ Graphic symbols and Labeling
ACTUATING DEVICES
They click into position and hold that position indefinitely. Detented valves have no normal position.
Represents spring offset/return; When un-actuated return to labeled envelope.
..\video\Edited\Detent vs Spring return.wmv

35. DCV:~ Graphic symbols and Labeling
FLUID POWER
Hydraulic Valves
DCV:~ Graphic symbols and Labeling
ACTUATING DEVICES
..\video\Edited\Push Button.wmv

36. DCV:~ Graphic symbols and Labeling
FLUID POWER
Hydraulic Valves
DCV:~ Graphic symbols and Labeling
ACTUATING DEVICES
..\video\Edited\Edited - How directional solenoid valve works -- dismantled. ✔.wmv
..\video\Edited\Solenoid Valve Working.wmv