Basics of hydraulics,principles,concepts

Hydraulics basics

1. BASIC OF HYDRAULICS

13. DIFFERENT COMPONENTS IN
HYDRAULIC CIRCUIT
PUMPS
FILTERS
D.C.VALVES
PR. CONTROL VALVES
NON RETURN VALVES
FLOW CONTROL VALVES
ACTUATORS
ACCUMULATORS
PR. INTESIFIER

14. FLOW CHART

15. TYPES OF POSITIVE
DISPLACEMENT PUMPS.
1.GEAR PUMP
2.VANE PUMP
3.PISTON PUMP
a)RADIAL PISTON PUMP
b)AXIAL PISTON PUMP
c)BENT AXIS PUMP
4.SCREW PUMP

16. 1.PUMP DISCHARGE IS CONSTANT REGARDLESS OF
PRESSURE.
2.THE OUTLET IS POSITIVELY SEALED AGAINST INLET.
SO, THAT WHATEVER FLUID GETS INTO THE PUMP IS
FORCED OUT THE OUTLET PORT.
3.SOLE PURPOSE OF THE PUMP IS TO CREATE THE FLOW.
4.PRESSURE IS CAUSED BY THE RESISTANCE TO FLOW.
5.MAINTAINING THE PRESSURE ALONE IS NOT THE
INDICATOR OF PUMP’S CONDITION. IT IS NECESSARY TO
MEASURE THE FLOW AT A GIVEN PRESSURE TO
DETERMINE WHEATHER A PUMP IS IN GOOD OR BAD
CONDITION.
WHAT IS POSITIVE
DISPLACEMENT PUMP ?

17. CAVITATION
A)WHEN THE PRESSURE DROP IN THE SUCTION LINE
INCREASES, LIQUID VAPORISES IN THE SUCTION LINE.
THESE VAPOURS OR GAS BUBBLES IN OIL WHEN PASSED
THROUGH THE PUMP AND COLLAPSED AT THE DELIVERY
SIDE OF PUMP WITH THE CONSIDERABLE FORCE( AT THE
DELIVERY PRESSURE) AND CAUSING DAMAGE THAT WILL
IMPAIR THE PUMP PERFORMANCE AND REDUCE THE LIFE
OF PUMP.
EVEN OIL HAS GOOD VAPOUR PRESSURE CHARACTERISTICS ,TOO
LOW AN INLET LINE PRESSURE PERMITS THE AIR
DISSOLVED IN THE OIL TO BE RELEASED. THIS OIL AND
VAPOURS MIXTURE ALSO EXPOSED TO THE LOAD
PRESSURE AND CAUSES DAMAGE

18. REASON
1. HIGHER SPEED-HIGHER PRESSURE DROP
2.ANY MODIFICATION CARRIED OUT
AFTERWARD
RECOMMENDED VACUUM
-A VACCUM OF NOT MORE THAN 12.2 PSI
Abs. AT THE INLET OR THE PRESSURE
DIFFERENCE OF 2.5 PSI WHICH IS GOOD
ENOUGH

19. INGRESSED AIR FROM
ATMOSPHERE
AIR FROM ATMOSPHERE, WHICH
CAN NOT DISSOLVE IN THE OIL, BUT
PASSES THROUGH THE SYSTEM AS
COMPRESSIBLE BUBBLES, WHICH
CAUSES ERRATIC OPERATION OF
VALVE OR ACTUATOR .

21. DOUBLE VANE PUMP

23. Axial piston pump consists of
Cylinder bockwith number of precision bores-each bore to
accommodate piston. It can rotate with shaft. Cylinder block engages
shaftthrough splines on the shaft.
Pistons–It has spherical shape at one end. Each piston is
accommodated in each bore of the cylinder block. Spherical end is
assembled to swash platewith piston shoe plate (retracting ring).
Swash plate-It is tiltable around shaft over a spherical washerand
it can hold number of pistons –pistons can swival freely around its
axis up to certain degrees. Yoke plateis fitted on the swash plate.
Shaft-Cylinder block engages shaft through splines on the shaft.
Shaft if assembeled to casingwith bearingand oil seal.
Valve platewith port connections.
Spherical washer, shoe plate, Yoke plate, bearing, spring and housing
are other parts of the pump.
AXIAL PISTON PUMP

27. RADIAL PISTON PUMP

28. FILTER-
A DEVICE WHOSE PRIMARY FUNCTION IS
TO RETAIN THE FOREIGN PARTICLES /
INSOLUBLE CONTAMINANTS BY SOME
POROUS MEDIUM

29. FILTER MEDIA-IT IS THE MEDIA USED TO TRAP THE
FOREIGN PARTICLES BY MECHANICAL MEANS.
TYPES
A)SURFACE MEDIA-IT IS KNOWN AS COARSE
FILTRATION i.e. STRAINER(WOVEN SCREEN)
B) IN DEPTH MEDIA–IT IS USED FOR FINER
FILTRATION.
FOR HYDRAULIC FILTER MEDIA, IT IS COMBINATION
OF CELLULOSIC, SYNTHETIC & GLASS FIBRE .
These materials are blended for specific performance, strength,
and durability and are usually resin impregnated to provide added
strength.
FILTERATION

30. FILTER LOCATION-THERE ARE
FOUR GENERAL LOCATION IN ANY SYSTEM .
1.INLET LINE
2.PRESSURE LINE
3.RETURN LINE
4.OFF LINE FILTRATION

31. STRAINER –COARSE FILTER
PRESSURE FILTER / RETURN
LINE FILTER-IN DEPTH FILTER
BETA RATIO =NO.OF PARTICLES IN UP STREAM SIDE > X/
NO. OF PARTICLES IN DOWN STREAM SIDE>X
X = SIZE OF PARTICLES IN MICRON

32. IF Beta RATIO = 75
i.e. 75 PARTICLES RETAINED FOR EVERY 1
PARTICLE THAT GETS THROUGH.
EFFICIENCY = (100 –100 / 75)
= (100 –1.33)= 98.7 %
SELECTION -
SILT CONTROL -B (3-5) = 75
PARTIAL SILT CONTROL -B(10-15) = 75
CHIP REMOVAL -B(25-40) = 75

33. FLOW RATE -CAPACITY OF FILTER TO
HANDLE THE FLUID QUANTITY IN LPM OR
GPM
PRESSURE RATING -MAXIMUM SYSTEM
PRESSURE THAT THE FILTER IS ABLE TO
WITHSTAND.
PRESSURE DROP –PRESSURE DROP
ACROSS THE FILTER SHOULD BE AS LOW
AS POSSIBLE.
FLUID COMPATIBILITY -FILTER MEDIA
SHOULD BE COMPATIBLE TO THE
HYDRAULIC OIL BEING USED IN SYSTEM

34. CHECK VALVES

37. GOOD
MORNING

38. DIRECTIONAL CONTROL VALVES
Directional control valve provides hydraulic connections :
•-to one or other ports of consumer .
•-disconnects from one or other,
•-variety of cross linkages ,
Solenoid transmits force in a linear path through an extension
of oil directing spool. The port connections are defined by
profile of the spool.
It can be
•2 way valve 2 position with 2 ports P,A.
•2 way valve 2 position with 3 ports P,A,T.
•4 way valve 3 position with 4 ports P,A,B,T
D.C.VALVES

39. VARIOUS POSITION OF
D.C.VALVES

40. PILOT STAGE D.C.VALVE

41. PR. RELIEF VALVE

44. TYPES OF ACCUMULATORS
DEAD WEIGHT TYPE.
HYDRO PNEUMATIC(N2).
BLADDER TYPE
PISTON TYPE

45. WHY IT IS REQUIRED?
TO COMPENSATE PULSATING FLOW.
TO BRIDGE A GAP BETWEEN DEMAND
AND SUPPLY.
THE ACCUMULATOR GETS CHARGED
DURING LOW FLOW RATE DEMAND
PERIOD. THEREFORE THE USAGE OF
ACCUMULATOR AVOIDS THE SELECTION
OF LARGE FLOW RATE PUMP, LARGER OIL
TANK AND LARGER ELECTRIC MOTOR.

46. ACCUMULATORS

47. Piston type accumulator

48. OIL CONDITION MONITORING

49. OIL CONDITION MONITORING
PERIODIC CHECKING OF OIL
1.CONTAMINATION
2.TAN >1.5
3.VISCOSITY
4.VISCOSITY INDEX > 95
4.WATER CONTENTS < 250 PPM

50. HOW TO TAKE SAMPLE ?
DYNAMIC SAMPLE -FLUID SAMPLE
MUST MAKE SURE THAT IT
REPRESENTS THE WHOLE POPULATION
OF THE CONTAMINANTS LEVEL THAT
EXISTS WITH IN THE SYSTEM UNDER
THE ACTUAL OPERATING CONDITION.
IN THIS CASE DYNAMIC SAMPLING
MUST BE TAKEN FROM THE FLUID IN
MOTION.

51. FLUID CONTAMINATION IS DEFINED
IN
FOLLOWING WAYS -
NAS (NATIONAL AERONAUTIC SOCIETY)
ISO (INTERNATIONAL STANDARD
ORGANISATION )

52. SAMPLE SIZE-100 ML
ISO 11/8 OR NAS 3
PARTICLE SIZE COUNTS
5-15 MICRON 2000
15-25 MICRON 178
25-50 MICRON 16
50-100 MICRON 1

53. CHECKING PROCEDURE.
CONTAMINANTS ANALYSIS IS PERFORMED
IN A HYDRAULIC SYSTEM, THE VALIDITY
OF RESULTS DEPEND UPON THE
FOLLOWING FACTORS -
1. EQUIPMENT CLEANLINESS
2. ENVIRONMENT IN WHICH SAMPLE IS
COLLECTED / EXPOSED.
3. METHOD USED TO COLLECT THE SAMPLE.
4. METHOD USED TO COUNT THE PARTICLES.
5. ACCURACY OF THE OIL ANALYSER.
6 ACCURACY IN INTERPRETING THE RESULTS

54. INTERNALCLEARANCES OF HYDRAULIC
COMPONENTS
GEAR PUMP 5-10 MICRON
VANE PUMP 5-10 MICRON
PISTON PUMP 1-5 MICRON
D.C.VALVE 5 –23 MICRON
PROPORTIONAL
CONTROL VALVE
10 MICRON
SERVO VALVE 1-4 MICRON
ACTUATORS 50-120 MICRON

55. VARIOUS TYPES OF SEALS

56. HYDRAULIC SEALS
TYPE OF SEALS MATERIAL
SEALCUP / BUCKET NITRILE(BUNA N),
NEOPRENE,
VITON,SILICON,PTFE,
BRONZE
IMPREGNATED
TEFLON, FIBRE
REINFORCED
COMPRESSION
PACKING(P/S,R/SW/S
‘O’ RING
SEAL(P/S,R/S,W/S)
PISTON RING C.I.

57. SYMBOLS USED IN
HYDRAULIC CIRCUITS

63. MAINTENANCE
It has been estimated that as much as 70% of
hydraulic problems may be traced directly due
to condition of hydraulic oil.
Clean oil prevents many possible break-downs.
Hence oil should be filtered at regular
intervals.
Oil filters should also be cleaned at regular
intervals.
It should be ensured that oil temperature
never exceeds over 50 -55 degree C.
Bleed the system at load lines, as far as
possible at the highest points.
Check level of oil in tank.
Arrest leakage immediately if any.
Check for oil contamination.

64. THANK
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