Fluid Power Control

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.

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

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.

 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.

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.

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

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

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

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

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

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.

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

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

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. **

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

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

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

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

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?

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

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

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

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

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.

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;

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:

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:

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:

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:

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.

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 ***

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.

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

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

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