65114878 Hydraulic System

8/3/2019 65114878 Hydraulic System

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BASIC HYDRAULICS WORKSHOP...

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International Maritime Training CentreTel. : 91-22-2570

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BASIC HYDRAULIC WORKSHOP

RevO.O,

CONTENTS1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. M 17. Hos 18. Se 19. 20.Advantages of hydraulic systems... ... ... ...1 Fundamental principles... ... ... ... ... '" ... ... 2-7 Block diagram of hydraulic systfi!:i\ns... Component and circuit symbols Hydraulic fluid Re

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INTERNATIONAL MARITIME TRAINING CENTRE


4/98

~;::BASIC HYDRAULIC WORKSHOP

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RevO.O July 03

AIM OF THE COURSE:1. 2. TO UNDERSTAND FUNDAMENTAL PRINCIPLES OF HYDRAULICS TO READ HYDRAULIC AND PNEUMATIC CIRCUIT DIAGRAMS WITH THE HELP OF SYMBOLS KNOW THE CONSTRUCTION COMPONENTS USED IN HYDRAU FUNCTION OF IMPORTANT

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10. CONSTANT TORQUE WIT PRESSURE AND SPEEDoc FLOW 11. INBUILT SAFETY - actuatorcan be stalledrat full load (even if relief valve lifts - it will reset immediately when overIQi:~d removed. is 12. AUTOMATIC BRAKING - by blocking flow, no brakes, linings etc. required. 13. CAN BE USED IN HAZARDOUS CONDITIONS.

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5/98


Re.{).O .hdy 03

PASCALS LAWPressure applied to a confined fluid is transmitted undiminished in all directions, and acts with equal force on equal areas, and at right angles to,them

1. The bottle with a IIqui.

is not com

bottom

an area each ushed on e, the entire receives a ~OOlb. push.

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INTERNATIONALMARITIMETRAINING CENTRE2

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6/98

BASIC HYDRAVUC WORKSHOP

RevO.O July 03

FUNDAMENTAL PRINCIPLES1.PASCAL'S LAW: Pressure exerted on a confined fluid is transmitted undiminished i

n all direction and acts with equal force on equal areas & at right angles to them. Hydraulics is a means of power tran,; Work is force acting through a distan~. WORK = FORCE x OIST,

2. 3. 4. 5. 6. 7. 8. 9.

10. 11.

15. 1 H.P. = 746 WATTS = 16. KW = L.P.M. x BAR/600. 17. H.P. = G.P.M. x PSI x 0.000583. 18. H.P. of a prime mover = GPM x PSI x 0.0007.

INTERNA TION}\[MARITIME TRAINING CENTF


7/98


RevO. 0 July 03

Hvdraulic Principle I: Movement de{!ends on FlowFor anything to move in a hydraulic machine, the actuators must be supplied withfluid flow. Nothing moves

without flow.

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"" '" l ...,) .,..:?'., ,'.0;;.;/ This cylinder is retracted. It ca'h"eXt~l1g i:9~lyjifittJ!3re%Ts"ffow into port A. If there is no flow into port A, the pistonwill not move.

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8/98

BASIC HYDRA VLIC WORKSHOP

RevO.O July 03

Hvdraulic Principle II: Rate of Flow Determines S~eedActuator speed depends upon rate of flow. The faster fluid fills the cylinder, the faster the piston will move. The faster fluid fills the expanding spaces in a

hydraulic motor, the faster the shaft will turn.

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Notice that in this case speed may be affected in one direction only. If the valve shifts fully the other way, cylinder speed will be normal in the other direction.

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MARITIME TRAINING CENTRE

5


9/98

BASIC HYDRAVUC WORKSHOP

RevO.O July 03

Hvdraulic Principle III: Load Determines PressureThe pressure developed in an actuator depends on the load. That is, pressure will rise until the force is exerts on the piston in a cylinder can move the load.

The greater the load, the higher the pressure will rise.

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Or, the load may be normal but there is not enough pressure available tomove it. The relief valve may be leaking or set too low. The pump may be slipping its total volume. Other leaks in the system may be absorbing all pump output and preventing the pressure in the cylinder from rising enough to move the load.

INTERNAtiONAL JJlARITIMETRAINING CENTRE

6


10/98


RevO.O July 03

5. A pilot line operates a valve or other control.

4. A drain line returns leakage oil to the reservoirs

3. The pressure line is working line

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1. The pu: Inlet Ii a worki line.

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Pilot: In many cases, movem

essure signal taken fromthe system. This line is shown siml a edrain line but not connected to tank thuswe can differentiate between a drain line and a pilot line. The pilot line canbe likened to the starting circuit of an electric motor - where control voltagesare much less than the main motor voltage. i Piloting is done in two ways: Internal - this is done from the same circuit as the one in which the component is located. External - this is when the pilot signal is taken from another pumps' circuit or from a remote location.

INTERNATiONALMARITIMETRAINING CENTRE

7


11/98


RevO.O July 03

BLOCK DIAGRAM OF HYDRAULIC SYSTEM:

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PUMP Gear Vane Piston

Hvd.Energy

Pressure Control

Direction Control

Flow Control

ACTUATOR Cylinder Motor

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Mech. Mech. Energy

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a. b. c. d. e. f. DIRE a. 1, b. 2 01 c. Diffe Manl FLOW C a. Meter in b. Meter out c. Bleed off d. Non-compensated e. Pressure compensated f. Pressure & temp. compensated.

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12/98


RevO.O July 03

Circuit - Representation

Using Graphical Symbols

~Hydraulic motor

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Pushing

PuIH ng

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R4\-\ciI'ct

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CD Att

Tilting

Press'oll

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BASIC HYDRA VLlC WORKSHOP

RevO.O July 03

1

ACTUA TORS & PUMPS

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SINGLE ACTING CYLINDER SPRING EXTENSION

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SINGLE ACTING CYLINDER SPRING RETURN

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IRECTION MP, FIXED ELiVERY 'ARIABLE DELIVERY, UNIDIRECTION PUMP VARIABLE DELIVERY, BI DIRECTION PUMP

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14/98

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15/98

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DIRECTIONALCONTROLS

~3 PORT,

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2 POSITIOND.C. v/v

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RevO.O July 03

METHODS OF OPERATION

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MANUAL

SOLENOID

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PUSH BUTTON

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RESERVOIR


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18/98

BASIC HYDRA ULIC WORKSHOP

RevO.O July 03

PRESSURE CONTROLS

Name

PilotINTERNAL

DrainINTERNAL

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RELIEF VALVE Limits max. syste. pressure

UNLOADING v/v

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INTERNAL

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19/98


RevO.O July 03

FLOW CONTROLS

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CHECK VALVE

PILOI OPERTED CHECK VALVE

6PUMP-

MOTOR UNIT

(FLOW DIVIDER)

INTERNATIONAL MARitiME TRAINING CENTRE

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20/98


RevO.O July 03

FUNCTIONS AND PROPERTIES OF HYDRAULIC OILFUNCTIONS:1. 2. 3. TRANSMITS POWER LUBRICATES COMPONENTS REMOVES AND AIDS IN DISSIPA HEAT

FROM THE SYSTEM

4. 5. 6.

1. 2. 3.

4. 5. 6. 7.8. 9. 10. COMPRESSIBILITY Additives are added to the oil to improve the abo~e properties and thus extend

the life of the oil.

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21/98


RevO.O July 03

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EFFECT OF VISCOSITY ON HYDRAULIC SYSTEMS:

IF THE VISCOSITY IS TOO HIGH: 1. The internal friction of the fluid will increase resulting in increase in the flow resistance. The machine and fluid temperat~re will increase.

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22/98

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24/98

BASIC HYDRA ULlC WORKSHOP

RevO.O July 03

IMPORTANCE OF RESERVOIRS RESERVOIR: Functions:1. To aid in expelling entrained ai.. 2. Cooling the hydraulic 3. Aids in,removin

1. Tank 2. It s en 3. B Ii4. 5. 6. 7.

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25/98


RevO.O July 03

PUMP INLET LINE(OPTION)

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RETURN LINE SEALED FLANGE

THERMOMETER AND SIGHT GLASS

END PLATE EXTENSION

Typical Industrial Reservoir


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26/98

I


RevO.O July 03

FILTERS AND CONTAMINANTS

Filter types:1. 2. 3. 4. 5. 6. 7. Suction line filter - about 100 - po microns. . . Pressureline filter - about 5 - 1 Icrons. Return line filter - about 20 - 4 Icrons. Offline filtration. Full flow filters. PropoJ&tiJilaal flo Filte

Maximum abrasion occurs due to particles slightly smaller or the same size as the clearance between moving parts.

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28/98

BASICHYDRAULIC WORKSHOP

RevO.O July 03

AIR BREATHER

START

...

TO AVOID THE INGRESS OF CONTAMINATIONFROM

AIR ENTERS THROUGH THE PERFORATIONS IN THE./i

THEATMOSPHERE ABREATHER IS USED

BREATHER

PASSES THROUGH THE ELEMENT, .THEN INTO THE RESERVOIR


29/98

INLET FILTER

START

FLU ID ENTERS THE,

THEN PASSES INTO FILTER HOUSINGfI,o-

ANDFINALLY THROUGH THEFILTER Ij

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ELEMENT

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1AS THE FILTER CLOGS

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WITHCONT.A.MINATION,THE PRESSURE DIFFRENCE ACROSS THE ELEMENT INCREASES!

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32/98

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THISINCREASE CAUSES THE BY-PASSTO OPEN ALLOWING FLUIDACROSS THE BY.PASS

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(; i;~:! AS THE BY-PASS OPERATES, J i:1 "' ISALSO ANINDICATOR . :,..::.J:!j/l' \'

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34/98


35/98

RETURN LINE FILTER

START

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FLUID ENTERS THE FILTER AND FLOWS INTO THE BOWL CONTAINING THE FILTER ELEMENT

FLUID THEN PASSES THROUGH THE ELEMENT AND OUT OF THE FILTER

AS THE ELEMENT CLOGS WITH CONTAMINATION THE RESISTANCE TO FLOW INCREASES

AT A POINT DETERMINED BY THE SPRING TENSION, THE BY-PASS .. VALVE OPENS THUS PROTECTING THE FILTER FROM COLLAPSE

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THIS CAUSES A RISE IN PRESSURE


36/98


RevO.O July 03

Hydraulic Fluid Cleanliness RequirementsCleanliness requirements for hydraulic fluids have changed significantly in recent years. The standard of cleanliness that was acceptable a few years ago is no

longer sufficient for many of today's hydraulic systems. This is especially truefor highly-automated facilities, such as electrohydraulic servo valves, numerically controlled machines, and aircraft and missiles system. A hydraulic system may be perfect with respect to the design and construction, but if the fluid thatis used in the system contains excessive contamination, either the operation ofthe equipment may be unsatisfactory or damage to the unit may occur used by various organization and individual A number of different classification system have il for the hydraulic and lubricating fluids that companies to define and measure the cleanlines are used in equipment. To standardize the me od used to express the level of particulate rds Organization (ISO) developed contamination in hydraulic fluid, the" .' rd that not only expresses standard IS04406. ISO 4406 i to specitVwthe required the level of particulate cont cleanliness wides a consistent

Hydr; custc clear recol follow hydral Drums.dirt and ( Drums s effects of The top of1 from falling i Hydraulic oi Equipmentpumps, etc of any hOSE

be thoroughlyCieaned prior be covered after use to prevent f Because many facilities use different typ'es1'ofjiflyara~nc'&fj'UIas in different system, equipmentthat is used to transfer fluid to these systems should be designatedand used for each different fluid to prevent cross-contaminatingnoncompatiblefluids. Even though fluid suppliers are careful to deliver only clean fluid, a filtration system should be used to transfer the fluid to the reservoir. The degree of,filtration should be the same as the filtration system that is used on the equipment. Manl, fluid suppliers will provide hydraulic fluid filtration system specifically

designedfor filtering fluid as it is added to the system. Facilities should establish and follow hydraulic fluid standards and practices to prevent thecontamination of hydraulic system from the improper storage and handling of hydraulic fluids.


37/98


RevO.O July 03

INGRESS FROM CYLINDER ROD SEALS

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PUMP INLET LINE FILTER

PUMP TENDS TO GRIND EXISTING D!RT AND GENERATE MORE AS A RESUL

BASIC FILTRATION OF A HYDRAULIC SYSTEM


38/98

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39/98

15

20

25

30

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50.

60

70

80 00 100

PARTICLE SIZE, mlcrometresISO solid contaminant

code.

Example: Sample size = 100 ml Particle size ranQe 5-15/lm 15 - 25 /l m 25 -: 50/l m 50 - 100 /l m >100/lm

Number of particles 150,000 5,000 1,250 250 50

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Thus, total number of particles... .

> 5 /l m = 156,550

>15 J.1 = 6,550 m These two values are plotted on the graph as shown, which gives the code as '18/13'


40/98


R,

Number of partioles per 100 mlllllltrns Code20/17 20/16 20/15 20/14 19/16 19/15 19/1419/13 18/15 18114 18/13 18/12 17/14 17/13

Over 5 p.m More than & up to500k 500k 500k 500k 250k 250k 2501

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IllUSTRATION OF A COUNTERBALANCEVALVE CIRCUIT.

A counterbalancevalve 'C' is usedwhen there is a tendencyof the hangingloadW tocausethe actuatorto 'creep'due to slight leakage at the spool of the direction control valve.

This can also I:>e achievedwith a pilot operatedcheckvalve in placeof the counterbalance valve.

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57/98


RevO.O July 03

General description These modules provide pilot operated check functions in oneor both service lines (A and B), the pilot supply coming from opposite service line to that in which the check acts. When closed, the check prevents flow from t

he actuator port to which it is externally connected. The construction of a dualcheck module is shown below:

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A


58/98


RevO.O July 03

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A. LOWERING CYLINDER

B. RAISING CYLINDER

Counterbalance valve.

Spool Is held wide open. (No restriction to motor exhaust.)

Low pressure here when directional valve Is centered.

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Pressure created here equall that required to 11ft spool allowing exhaust flow.(Braking force.)

Remote control pressure Is directly under spool. (Large area.)

A. ACCELERATION OR CONSTANT SPEED Brake valve.

B. BRAKING


59/98


RevO.O July 03

COUNTERBALANCE

VALVE

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opens to permit free When the cylinder is be e valve can be internally flow forreturning the cylin drained. In the lowering position, when the valve must be open, its secondary port is connected to tank. In the reverse condition, it does not matter tl:lat load pressure is effective in the drain passage, because the cheek valve bypasses the spool. .


60/98


61/98


RevO.O July 03

FLOW CONTROL VALVESThe function of these valves is to controlthe flowof oiland thus, the speed of the actuators. They are normally fitted after the direction control valve to prev

ent

power loss.

.

Flow control valves are essential direction only and this direc1. thus care should be t

designed to control flow in one the body by an arrow & d correctly.

1. 2. 3.

Since, Flow a L\P any change in ...thepressure drop across theI

orifice of the flow control valve will result in change in flow. To prevent this, we have valves called Pressure compensated flow control valves.


62/98


RevO.O July 03

TYPES OF FLOW CONTROLA

a

METER IN

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BLEED-OFFCONTROL

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BI"ed-Off Circuit

INTERNATiONAL MARlfIME:fAAfNIN~ CENfRE

46


63/98


RevO.O July 03

ACTUATORSThese convert hydraulic energy into mechanical energy. There are two types of actuators: 1. Cylinders: these are linear hydraulic actuators. 2. Motors: these ar

e rotary hydraulic actuators.

CYLINDERS:There are various types of cylindl 1. Single acting 2. Spr. 3. Do 4. Do 5. Tan


64/98

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ROD END HEAD ROD END PORT OPTIONAL AIR VENTS (FOR BLEEDING AIR FROM CYLINDER) PISTONSEALS CAP END HEAD TIE ROD CAP END PORT?=s

CUSHION COLLAR

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BODY Typical cVll der construction. n

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65/98

1. Exhaust flow passes freely out of cylinder until. . .

5. Check valve allows free flow to piston for

extension.

2..Plunger enters cap.. .

4. Rate of decelerationis controlled by adjustable opening.

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3. Nowflowmust take restricted path causing the piston to decelerate.

CYLINDER CUSHIONS - ROD RETRACTINGINTERNATIONAL MARITIME TRAINING CENTRE 49


66/98

CYLINDER PORT

CUSHION NOTE:Closingof the ADJUSTMENT cushionadjustment screw SCREW shouldbe donewithcare.

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67/98

CONN~cr\NG p.OO v.I\NOOV'l

pof{{S

PistoN


68/98


RevO.O July 03

ACCUMULATORSSince hydraulic fluids are essentially incompressible, they do not have"the ability to store power. Hydraulic accumulators store the potential energy that is in

the incompressible fluid for subsequent conversion to useful work.

Functions:1. Pulsation damper and shock absorber: It dampens the pulsations pressure surges can would this st Combl Safety failure. POW~j rea olerable levels. Also, heavyIve in the system - thisrs.~.bs:~f:;111&:cushion

2. 3. 4.

1. 2. 3. 4. The

Note: Never open any componenllflliJlim71i'ltl'n::I@tne hydraulic ensuring thatthe accumulator fluid has been drained to tank.Other ways of reducing vibration:

system

before

1. - Clamp pipes at short intervals...2. 3. If possible pump to have flexible hoses at suction at delivery ends for about 1/2 mtr. Motor and pump to be mounted on foundation using shock absorbers.


69/98

.....


RevO.O July 03

TYPES OF ACCUMULATORS

Air /VentSpring

11Gas Port

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Pinon.Oil

A

Shelt

..' 'Oil Port A.BLADDER

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Oil Port

B. SPRING LOADED

C. WEIGHT LOADED

D. DIAPHRAGM

Types of Although types ar in populBladder between a valve 1 always rE and floats bag closes lesigned to g its life.

Diaphragm Adiaphragm se limited. The sc.Charging an On hydraulic system using a charging and gauging assembly to accumulator used should be on hand for use of maintenance people. A pressure bottle ofoil pumped (dry) nitrogen should also be on hand. The assembly may also containa shut off valve between the gauge and bottle adapter so the assembly can be left attached to monitor gas pre-charge. All oil must be discharged before checkingor adjusting precharge pressure.INTERNATIONAL MARITIME TRAINING CENTRE

device. Rubber laximum size is harged.

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Thread to Fit Gas Port on Ac:c:umu~tor


70/98

Threld to Fit Preuure Sonles

Adapter for Bo~.. Wit:L.H7

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CHARGING AND GAGUING ASSEMBLY


71/98

ACCUMULATOR

START -~

THE ACCUMULATOR CONSISTS OF TWO COMPARTMENTS

ONE THE BAG WHICH ... CONTAINS THE GAS

(NITrOGEN) THE OTHER A STEEL SHELL INTO WHICH THE FLUID IS PUMPED

-+THE GAS IN THE BAG PRODUCES A RESISTANCE TO THE PUMP FLOW THERE BY CREATING PRESSURE

TO ENSURE THE B~G DOES NOT EXTRUDE AND BURST, A VALVE IS FITTED TO ELIMINATE THIS

SO THAT THE ENERGY CAN BE STORED IN THE ACCUMULATOR

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WHEN FULLY DISCHARGED THE GAS IN THE BAG INFLATES IT TO FILL THE ENTIRE STEEL SHELL


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ACCUMULATORSFunction A hydraulic accumulator is a vessel in which a fluid may be kept underpressure. When liquid is supplied to the accumulator through the oil valve, therubber bag is compressed, and the pressure of the oil mounts. When the oil pressure drops, the rubber bag expands, and the accumulator delivers oil to the hydraulic system into which it is connected. Hydraulic Ac Components The hydraulic components 1. A stel 2. Arul the 3. A bj t 4. 2. There is a slit or tear some 10-4

0 cm from the bottom end of the bag. Causes: After installing the bag it has been charged too rapidly. During installation, tre entire oil valve must be introduced into the accumulator. The nether part of the bag may then be forced upwardsor even folded on itself. With a high charging rate, the bag is not 'me to assume its correct shape, but is 'ned in its lower peripheral parts. own the middle nto the g of the bag must slow rate in order to open up into its

e is tightened alve proper bag will be of the bag ,hen cause bag. e vented!

Malfun Faulty relative. compon malfuncti and may

installation

~

surveillance Typical dam 1. The I at a charc ~, Cause: T to nothing (through diffusl years of operation or because 0 charging valve or through failure to check the tightness of the valve after charging). The bag has been compressed by the hydraulic circuit pressure until the upper part of the bag has folded itself over the charging valve

2

.:I

and been punctured by it.

.

.

There is a slit or tear some 10-40 cm from the bottom end of the bag.

HYDRAULIC

PRESSURE ACCUMULATOR


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BASIC HYDRA vue

WORKSHOP

RevO.O July 03

ACCUMULATORS

N.B. Check the charging pressure of the bag every year (approx. 1000-hour intervals) and also when replacing the oil cooler in the system. Insufficient gas pressure in the bag may cause the following kinds of damage: 1. The rubber bag in the accumulator i compressed by the hydraulic circ pressure, and is torn by the charging val A new accumulator must be installed. 2. Hydraulic pumps and motors down. They require a pressurl 3. Excessj eventua.~, '!fuP" too fa(~)f operati ' Tocharge a h' of Fig. HAGGLUN bar (600 k 2 meters) W24 co bottle. W24/14 Chargin(N2). (Ail 1. C ac , 9. Close the nitrogen bottle shut-oft valve tightly 10. Open the discharge valve of the 3-way valve to vent the pressure in the filling hose to the outside air. 11. Return the reducing valve to zero. 12. Remove the charging equipment from the nitrogen bottle and from the accumulator. 13. Use a soapsolution in water to check that e accumulator charging valve is perfectly d saf

ety screwag to the f filling, and erator. cessary to fit bottle.

2.

3. 4. 5. 6. 7. 8.

scn oper tight. . Connei nitroge reducin Open until t Open t Adjust theieducingv charging pressure (see table obtained. Turn the 3-way valve filling screw clockwise, but not too tightly as this may damage the accumulator chargingvalve. Fill the accumulator bag with nitrogen. Check the nitrogen pressure in the bag whenthe temperature and pressure of the gas have stabilized. When the correct press

ure has been obtained, back out the filling screw of the 3-way valve.

Connector nitrogen

W24 for' bottle

,

-

.

NITROGEN HARGINGQUIPMENT C E

INTERNATIONALMARITIMETRAINING CI:I\I"TRE

57


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Maintenance tip: watch gage to monitor precharge pressureThe precharge pressure in a bladder should be checked at least once in a month according to one accumulator manufacturer. This simple preventive maintenance action will assure consistent flow to the cirGuit and extended bladder life. The conventional way to check prechar! all pressures from hydraulic circuit. Then install a gage head assembly, the precharge pressure fl the next a to shut of the pump and discharge cap the accumulator charge value, Ive with its tee handle. If c

edures and go to

For multiple-accumulatorcircuitsln'~'ge~iII indicate the condition of the lowestprecharge pressure. If that pressure shows less than required, checks of each individualaccumulatorwill be necessary.


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SAFETY AND PRECAUTIONSBEWARE OF :

1.

leaks

: can make the afe}rSlippery. : can constitute a ~pour and fire hazard. : leaki


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RELIEVING SYSTEM PRESSUREPressure may be due to external loads or forces. Eliminate them. . Lower or moveall parts to the rest, 2r untensioned position before shutting the system down.ay be counterbalancing loads. . Carefully open adjustable valves t an be reset). (Note the setting first, so the valv . Jack or wedge the load ulic pressure mechanically, if n

Pressure or charge . Se . We di .

Eve

.


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LOWER OR MECHANICALLY SECURE ALL SUSPENDED LOADS

ISOLATE THE ELECTRICAL POWER SUPPLY

SAFETY PROCEDURE FOR SHUTTING DOWN MACHINES


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BASIC HYDRAULIC WORKSHOP SYSTEM INSPECTION AND MAINTENANCE CLEANING OF HYDRAULICFLUIDS

RevO.O July 03

How clean should the Hyd. Fluid be ? Hydraulicfluid serves as a medium for transmittingforce from one place to another. It must quicklyreflectchanges in force's

directionand magnitude. To meet these needs, a fluidmust have: . enough viscosity to efficientlytransmit fo~ce, prevent cavitation and guard against overheating m components sufficientlubricatingcapabilityto protect and 60 deg.C - ideal range is 50-55 . temperature between the fluid's pour deg.C anti-wear protection,ifne oxidatio . adequ

. . .

. . .

.

,

good drust inh resistal comp

..

Res Freqi Envir Equipt Onlyn Whydo Results

. .

.

10%

-

5% - u

10% -

5%-

inade 70% poo

-

WARNING- Before breaking a cTrc'f:iif~r:m~6ti."*m'*aKepower is off and system sure

pressure is released. Lower all vertical cylinders and discharge accumulators.CAUTION - Absolute cleanliness is essential when working on a hydraulic system.The presence of dirt and foreign materials in a system can result in serious damage or inadequate operation.

NOTE - Discard and replace all '0' rings, gaskets and back up rings removed during disassembly.

INTERNATIONAL MARfTrri/f~iAAINING CENTRE

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Documents

65114878 Hydraulic System