basic training - Hydraulics 07.01.2015
Jörg Prezer
Seite 1
Hydraulic basics topics: Hydrau auli lic c flui fluid d - Hydr
common comm on so sorc rce e of co cont ntam amin inat atio ion n in a hy hydr drau auli lic c syst system em filtration oil analysis – purity class of hydraulic fluid
hydr dr.. sy symb mbol ols s acco accord rdin ing g to DI DIN N ISO ISO 1219 1219 - hy
types of valve lves
- Pump systems - Tube coup coupling ling syste system m - Maintenance and Assembly ______________________________________________ ____________________________ ____________________________________ ______________________________________ _________________________________________ ________________________ ___
Inttro rodu duc ction tion to the hy hydr drau auli lic c con ontr trol ol syste stem of the - In the WKP WKP 600 600 S
readin reading g and und unders erstan tandin ding g the hy hydr dr.. diagra diagram m
technica ical site visiti iting and operation of the WK WKP 60 600 S
07.01.2015
Jörg Prezer
Seite 2
Hydraulic basics topics: Hydrau auli lic c flui fluid d - Hydr
common comm on so sorc rce e of co cont ntam amin inat atio ion n in a hy hydr drau auli lic c syst system em filtration oil analysis – purity class of hydraulic fluid
hydr dr.. sy symb mbol ols s acco accord rdin ing g to DI DIN N ISO ISO 1219 1219 - hy
types of valve lves
- Pump systems - Tube coup coupling ling syste system m - Maintenance and Assembly ______________________________________________ ____________________________ ____________________________________ ______________________________________ _________________________________________ ________________________ ___
Inttro rodu duc ction tion to the hy hydr drau auli lic c con ontr trol ol syste stem of the - In the WKP WKP 600 600 S
readin reading g and und unders erstan tandin ding g the hy hydr dr.. diagra diagram m
technica ical site visiti iting and operation of the WK WKP 60 600 S
07.01.2015
Jörg Prezer
Seite 2
Hydralic fluid Function of the fluid in the Hydraulic system : Transmit the force and movement Hydralic
power is defined as the product of pressure and flow rate
pressure force volume speed 07.01.2015
Jörg Prezer
Seite 3
Hydralic fluid Subd Subdiv ivis isio ion n of the the hydr hydral alic ic flui fluid d – mineral oils : Accor ccordi ding ng to DI DIN N 5152 51524 4 the the hy hydr drau auli lic c oil oil is su subc bcla lass ssif ify y into into 4 gr grou oups ps.. Thes Th ese e oils oils are are de dete term rmin inat ated ed by the the us used ed ad addi diti tiv ves: es:
•
Group H – mine minera rall oils oils with withou outt addi additi tion onal al addi additi tive ves s
•
Group HL – impr improv ove ement ent of the the res resist istance ance to agein geing g and and corro orros sion ion
•
Lubric Lub ricat ating ing oil oils s used us ed by syst system em pres pressu sure re to to 200b 200bar ar and and no norm rmal ally ly ther therma mall load loads s
Group HLP – further improved of the re resistance to wear and load viscosity-temperature characteristics capacity, as well as improve the viscosity-temperature
•
Grou Group p HLP HLPD – addi additi tion onal al pro proper pertie ties as disp disper ers sing ing (wat (water er retai etaini ning ng effe effect ct)) and and dete deterg rgen entt (cle (clean anin ing g effe effect ct) )
gene ge nera rall lly y us used ed in hy hydr dral alic ic syst system ems s 07.01.2015
Jörg Prezer
Seite 4
Hydralic fluid c hem. characteristics: • corr corros osio ion n prot protec ecti tion on • low low vi vis scosi cosity ty chan change ges s - visco viscosit sity y pressu pressure re char charact acteri eristi stics cs - temp temper erat atur uree-de depe pend nden ence ce of visco iscosi sity ty
comp mpat atib ibil ilit ity y with with the the syst system em • co - no swel welling ling of the the sea seal mate materi ria als, ls, paint aints s, … high gh fla flash shin ing g po poin intt • flame-resistant - hi
low w ther therma mall expa expans nsio ion n co coef effi fici cien entt • lo rule of thumb thumb : oils oils increa increase se in in volu volume me by by 0,63 0,63..0 ..0,76 ,76 % of their their total total – rule volume for each 10°C 10°C temperature temper ature increase 07.01.2015
Jörg Prezer
Seite 5
Hydralic fluid c hem. characteristics: • oxidation resistance (no acid formation) - ageing resistance
• Less air input and good air output - high temperatur makes the air release property significantly worse
• good dielectric (isolating) properties
07.01.2015
Jörg Prezer
Seite 6
Hydralic fluid mech. and phsical characteristics: • shear stability of a fluid - mechanical load of the fluid at control edges and valve seats
• lubrication ability - is indicated by the Brugger-test according to DIN 51347-2
• high density - high density allow to transfer higher performances • low compressibility
07.01.2015
Jörg Prezer
Seite 7
Hydralic fluid mech. and phsical characteristics: • low foam formation • high wear resistance to: − dirt (abrasion) − cavitation (fatigue) − corrosion (e.g. by water)
• dirt removal • good filterability - attention: by filteration with filterelements <2µm additives can also be filtered
07.01.2015
Jörg Prezer
Seite 8
Hydralic fluid contamination Reason of contamination:
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Jörg Prezer
Seite 9
Hydralic fluid contamination Reason of contamination: e.g. typical clearances on valves: - Servo valve => 1..4µm - Prop. Valve => 1..6µm => 2..8µm - Directional control valve
07.01.2015
Jörg Prezer
Seite 10
Hydralic fluid contamination Reason of contamination:
missing or inadequate maintenance • no filter replacement • filling with nonfiltered oil
assembly • tinder, welding spatter, rubber particles, liquid remaining, grinding dust, metal chips, sand, fibres,etc.
• lack of cleanliness by component replacement • lacking inspection of the hydraulic fluid at regular intervals 07.01.2015
Jörg Prezer
Seite 11
Hydralic fluid contamination Reason of contamination:
plant operations - inner system influences
plant operations - external system influences
• inner contamination accrue constantly
• biggest dirt ingress is coused by cylinder
• non-closed system openings
07.01.2015
Jörg Prezer
dirt particles will be produced by wearness or result by the aging of the oil
Seite 12
Hydralic fluid contamination Consequences of wear: Abrasion: •
caused by particles between reciprocating surfaces
effects: – increase in play, external oil leak, loss of holding ability and – additional wear and contamination of the fluid 07.01.2015
Jörg Prezer
Seite 13
Hydralic fluid contamination Consequences of wear: Erosion: •
existing particles clash with high velocity against the corners and edges of the system
effects: – increase in play, leaking/damaged seat and plug, piston jamming and – additional wear and contamination of the fluid 07.01.2015
Jörg Prezer
Seite 14
Hydralic fluid contamination Consequences of wear: Deposition by adhesion : •
excessive load and/or a reduction in fluid viscosity can reduce the oil film thickness
effects: ─ clamping of the materials (metal-to-metal contact) ─ malfunction of the componentes, e.g. piston jamming at valves 07.01.2015
Jörg Prezer
Seite 15
Hydralic fluid contamination Consequences of wear: Surface fatigue: •
surfaces damaged by particles are subjected to repeated stress effects: – smallest cracks in the surface are hollowed out this causing a break off the material and – additional wear and contamination of the fluid
Oil ageing: •
leads to deposits, filter will clogging quickly
07.01.2015
Jörg Prezer
Seite 16
Hydralic fluid oil analysis and care
Oil care by:
• system filters
• permanent offline filter units
• mobile bypass filteration 07.01.2015
Stefan Hertel
Seite 17
Hydralic fluid oil analysis an d care
Overview system filters: • suction filters => pump protection
• pressure filters => direct protection of the components
• return line filters => filters the contamination which has entered the system as a result of component wear
• tank breather filters => protection contamination from entering the tank during tank breathing 07.01.2015
Jörg Prezer
Seite 18
Hydralic fluid oil analysis and care
Oil analysis by: • oil sampling for analysis in laboratory - detailed analysis (viscosity, Brugger, contained additives, wear components, water content, etc. ) for particle countint by oil diagnostic
device - immediate particle counting at place
• permanent oil analysis by ConditionMonitoring system 07.01.2015
Jörg Prezer
Seite 19
Hydralic fluid Brugger test
07.01.2015
Jörg Prezer
Seite 20
Hydralic fluid Brugger test
Limits: -
For general hydraulic:
>30 N/mm²
- For fast and proportional hydraulic: >50 N/mm² (Water has an Brugger value of about 19 N/mm²) 07.01.2015
Jörg Prezer
Seite 21
Hydralic fluid oil analysis and care • Cleanliness requirements for hydraulic components
classification of solid particle contamination follows ISO 4406/1999:
– to determine the cleanliness level the particles present in 100 ml fluid are counted, sorted according to size & quantity and classified into particle ranges
07.01.2015
Jörg Prezer
Seite 22
Elements of hydraulic circuits mechanical energy
hydraulic energy
pumps
energy converter
lines
control elements
hydraulic circuit =
07.01.2015
cylinder/motors/ rotary drives
valves
tranporter of energy
electic control
mechanical energy
actuators
- muscle
= Jörg Prezer
- nervous system Seite 23
Elements of hydraulic circuits hydr. symbols (DIN ISO 1219)
07.01.2015
Jörg Prezer
Seite 24
Elements of hydraulic circuits hydr. symbols (DIN ISO 1219)
07.01.2015
Jörg Prezer
Seite 25
Elements of hydraulic circuits hydr. symbols (DIN ISO 1219)
07.01.2015
Jörg Prezer
Seite 26
Elements of hydraulic circuits hydr. symbols (DIN ISO 1219)
07.01.2015
Stefan Hertel
Seite 27
Elements of hydraulic circuits hydr. symbols (DIN ISO 1219)
07.01.2015
Stefan Hertel
Seite 28
Elements of hydraulic circuits hydr. symbols (DIN ISO 1219)
07.01.2015
Jörg Prezer
Seite 29
Valves
Characteristics connection interfaces •
Standardized connection interfaces (according to DIN 24340A6/ ISO 4401) allow worldwide replacement of valves by independentce from manufacturer
07.01.2015
Jörg Prezer
Seite 30
Valves direction valves - direct operated
Characteristics •
the housing is mode of pressure-tight hydraulic castings iron
•
the canals (P-T-A-B) are poured in with the housing at the same time
•
main bore is lapped
•
the piston´s ring groove serve as pressure balancing and for a better the forming of a lubricating film
Important: piston-sleeve-valves show a certain leakage => oil flow rate from range with high pressure to range with low pressure e.g. canal P to A/B or canal A/B to T
07.01.2015
Jörg Prezer
Seite 31
Valves direction valves - direct operated
Operation modes:
normal position
• electically 4/3 direction valve; direct operated
Solenoid "B" actuated => flow rate from P-A; B-T
07.01.2015
Jörg Prezer
Seite 32
Valves direction valves - direct operated
Operation modes: • mechanically activity takes a variety of forms. The returnes into normal position achieved by a spring normally
activity by cam/roles
07.01.2015
activity by hand lever
Jörg Prezer
Seite 33
Valves direction valves - direct operated
Operation modes: • emergency actuation a special form of mechanical actuation
in case of piston jamming or power failure, the valve (piston) can be moved.
07.01.2015
Jörg Prezer
Seite 34
Valves direction valves – pilot operated
Operation modes: • fluidic activity because of the big actuation forces direct operating over valve size NG 10 is not useful
Operation is made by pressurisation the auction cylinders of the valve piston
07.01.2015
Jörg Prezer
Seite 35
Valves direction valves – pilot operated
Operation modes: • electro-hydraulic valve is pilot operated by an NG6 valve witch is mounted on the main valve internal pilot oil supply internal/external: •
a minimum pilot pressure (7-15 bar) must be ensured for all operating conditions of the directional valve => pilot pressure can be worn internal from the P-chanal or external by the X-port => in case of high dynamic pressure in the return line (T-chanal) external pilot oil drain, by the Y-port, is needed
a malefunction of pilot operated valves is often the result of problems in pilot oil supply
07.01.2015
Jörg Prezer
Seite 36
Valves direction valves – pilot operated
Operation modes:
normal position
• electro-hydraulic Solenoid „A" actuated => flow rate from P-B; A-T
Solenoid „B" actuated => flow rate from P-A; B-T
07.01.2015
Jörg Prezer
Seite 37
Valves direction seat valves
Characteristics •
piston-sleeve-valves show a certain leakage due to their play between piston and housing
•
seat valves realised the leak-tight sealling of the ports by a ball or conical shape and seat
seat valves require a highly operation force, this means particularly stong solenoid
disadvantage of direct operated seat valves is a small stroke and, as a result, the small oil volume flow rates
large volume flow rates can be realized by pilot control of the main stage
07.01.2015
Jörg Prezer
Seite 38
Valves direction seat valves
Functional principle • direct operated
• pilot operated
07.01.2015
Jörg Prezer
Seite 39
Valves 2 way slip-in cartridge
Characteristics • slip-in cartridge valves designed for compact block installation • Leak-free valve charecteristic as: - hydraulic controlled seat/check, or pressure valve => depanding of pressure build-up in the main ports A and B
- active pilot operated 2/2-way cartridge valve => Pilot pressure actively opens and closes the main poppet independent of pressure in the main ports 07.01.2015
Jörg Prezer
Seite 40
Valves 2 way slip-in cartridge
Functional principle •
The varying of the valve elements; slip-in cartridge, cover, and pilot system permit combinations for single and complex functions
07.01.2015
Jörg Prezer
Seite 41
Valves 2 way slip-in cartridge
Functional principle normally open
normally closed
sleeve cone spring spacer ring cover unit
07.01.2015
Jörg Prezer
Seite 42
Valves check valves
Characteristics • component parts: – hardened ball or cone – seat – spring (generally 0,5…5 bar)
• Leak-free valve charecteristic as: - line mount check valve - cartridge designe for block installation - flange design for directly mount on surfaces 07.01.2015
Jörg Prezer
Seite 43
Valves check valves
Functional principle • direct operated check valve - provide free flow in one direction (1->2) and block the flow in the counter direction (2->1)
• pilot operated check valve - provide free flow in direction (3->2). The flow in the counter direction (2->3) is only given when pilot pressure is applied on port 1
07.01.2015
Jörg Prezer
Seite 44
Valves pressure valves Function types •pressure relief valve - primarily protection of system pressure - pump control of variable displacenemt pumps with pressure compensator
•pressure reducing/control valve - the secondary pressure is limited to the preset pressure value independently of the input pressure
•pressure switching valves - a hydralic switching operation will be triggered when it reaches the adjustable pressure value => e.g. pressure dependent shut off valve, pump venting valve, 07.01.2015
Jörg Prezer
Seite 45
Pumps selection The choise of a pump type depends on the application and the cycle as well as: • combination of possible pump controller • necessity of simultaneous motions -> pump controls with double pumps or pump combination of different pump designs • system pressure • availability and ease of maintenance • maximal sound pressure level • price 07.01.2015
Jörg Prezer
Seite 46
Pumps Overview pump types Pump design external gear pump
max. pressure range [bar]
160..250
internal gear pump
160..210
vane pump
160..210
Flow rate Displacement
fixed fixed
Speed range [U/min]
Sound pressure level [dB(A)]
800..3000
< 60
800..3000
< 50
fixed/ variable
600..3000
350
fixed/ variable
500..2500
< 75
Radial piston pump
280/350
fixed/ variable
500..2500
< 70
screw pump
80
3000..5000
< 50
axial piston pump
07.01.2015
fixed
Jörg Prezer
< 60
Seite 47
Pumpen axial piston pump 9
Parker PVplus 1
4
component parts
2
1. servo piston 3
2. rolling bearing 3. shaft drive 4. drain port 5. swash plate 6. piston and slipper 7. barrel 8. pump body
7 5 10 07.01.2015
6
8
Jörg Prezer
9. pump compnesator 10. servo spring Seite 48
Pumpen axial piston pump Rotating group valve plate cylinder block piston and slipper
07.01.2015
Jörg Prezer
Seite 49
Pipe fitting system Walterscheid flare tube fitting 37° the Walterscheid flare fitting design consists of four components: • fitting body according to DIN 2353 • centre unit • Ioose collar • nut The centre unit - effects the transition from the 24°taper of the fitting body to the 37°flare connection 24° taper
07.01.2015
37°flare connection
Jörg Prezer
Seite 50
Pipe fitting system Walterscheid flare tube fitting 37° The clear advantage for the user: • Higher assembly safety than cutting ring • Lower starting torque
High precision tightness due to elastomer sealing for both points of separation
07.01.2015
Jörg Prezer
Seite 51
Maintenance and Assembly The most important basic principles of a hydraulic technician are: •
pay attention to meticulous cleanliness in his surroundings and during assembly work (even if it is sometimes difficult).
•
never install a component that is dirty or damaged.
•
never do any assembly work on a unit if the electric motor is running (not even in bypass!!) or if the accumulator is filled.
•
never dismantle a component or loosen a screw connection if the plunger is not supported mechanically, or if any other dangerous movement can occur.
•
Never mix different media.
07.01.2015
Jörg Prezer
Seite 52
Maintenance and Assembly The most important basic principles of a hydraulic technician are: •
The first step when switching the electric motor on is to check the direction of rotation while bleeding the pressure line simultaneously using suitable connections (the pump can be damaged already by running 10 sec in the wrong direction of rotation).
•
After that a static pressure test follows without activating valves and without switching on the accumulator.
•
Then the air bleeding of the pipes and the components such as cylinders and motors follows.
•
First start is always at lowest pressure (set pressure relief valve or pump controller to minimum), slowest speeds (choke valves and set values of prop. valves set at minimum) and always without the accumulator being switched on.
07.01.2015
Jörg Prezer
Seite 53
Maintenance and Assembly Avoid contaminations •
In order to obtain perfect performance and the longest possible life span of a hydraulic system, the assembly and commissioning are of decisive importance, as well as perfect project planning.
•
The component gap widths of sometimes less than 2mm require the cleanest working manner during assembly.
•
Sources of contamination during interim storage are: – dust, shavings, fibers, remains of paint, sand, remains of packaging, water, means of preservation, rust
• Compulsory: Check every component visually before installation and pay attention to the exact closure of the connections.
07.01.2015
Jörg Prezer
Seite 54
Maintenance and Assembly Avoid contaminations
Sources of contamination are: •
During unit assembly (flexible tubes, piping, oil, cleaning rags welding, grinding, drilling, etc.) – scaling, welding beads, rubber parts, caustic and flushing agents, separating and wheel wharf, drilling chips, sealing component, paint, fibers
• Compulsory: – Connections of every component must be kept closed until they are about to be installed. – No mechanical work during hydraulic assembly – Clean piping and flexible tube lines also when fitting and clean thoroughly before final assembly – Use cleaning cloths that are free of fibers and fluff – Never do any subsequent welding on pipes or tanks – Clean oil tanks thoroughly before filling with oil – only fill in finely strained oil 07.01.2015
Jörg Prezer
Seite 55
