Hydraulic System

1. Diapositiva 1

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Komatsu Utility Europe
Customer Service Department
Pag. 1 di 20

2. Diapositiva 2

Hydraulic System : Main Principle
FLOW: determines the speed of the work equipment.
Speed of work equipment is determined by the amount of pump flow.
Greater the pump flow the greater the speed.
Lesser pump flow creates slower speeds.
Pump flow rate is determined by the pump swash plate angle
and rpm.
PRESSURE: determines the amount of force the work equipment can exert.
Pressure is determined by resistance up until maximum relief pressure is reached.
Resistance can come in two forms:
Flow rate and size of port the oil must pass through.
Amount of resistance from the work equipment.
When maximum relief pressure is reached the machine cannot exert any more force and the work
equipment stops.
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Komatsu Utility Europe
Customer Service Department
Pag. 2 di 20

3. Diapositiva 3

Hydraulic System : Main Principles
Pump RPM
Pump Swash Plate Angle
When the pump rotation
speed increases, the
pump flow increases.
This is directly effected
by engine rpm.
As the pump swash
plate angle increases
more fluid can fill each
chamber increasing the
flow.
When the pump rotation
speed decreases, the
pump flow decreases.
This is directly effected
by engine rpm.
As the pump swash
plate angle decreases
less fluid can fill each
chamber decreasing
flow.
This is valid also for the gear pump
not represented here
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Komatsu Utility Europe
Customer Service Department
Pag. 3 di 20

4. Diapositiva 4

Hydraulic System : Flow/Pressure Relationship
The relationship between flow and pressure is shown in the Hydraulic Output Curve.
With all hydraulic equipment the relationship between flow and pressure is inversely
proportional: as pressure increases flow decreases and as pressure decreases flow
increases.
Flow
(Q)
Hydr. POWER is constant
=
QxP
Pressure (P)
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Komatsu Utility Europe
Customer Service Department
Pag. 4 di 20

5. Diapositiva 5

Hydraulic System : Variable Displacement Pump
BASIC PRINCIPLE
1. Control of pump swash plate angle
The pump swash plate angle (pump
discharge amount) is controlled so that LS
differential pressure PLS (the difference
between pump (discharge) pressure PP and
control valve outlet port LS pressure PLS)
load pressure of actuator) is constant.
(LS pressure PLS=Pump discharge
pressure PP-LS pressure PLS)
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Komatsu Utility Europe
Customer Service Department
Pag. 5 di 20

6. Diapositiva 6

Hydraulic System : Variable Displacement Pump
Pump Discharge Q
(or Pump Displacement D)
<If the PLS is lower than the PLS set
pressure>
LS differential Pressure ⊿PLS
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Komatsu Utility Europe
Customer Service Department
Pag. 6 di 20

7. Diapositiva 7

Hydraulic System : Speed Up
WETT001304
Komatsu Utility Europe
POWER MODE & SPEED UP ADVANTAGES:
–
–
–
–
–
–
PERFECT CONTROL OF THE AVAILABLE POWER
NO ENERGY LOSS AND COSTS SAVING
SELF-ADJUSTMENT SYSTEM ACCORDING TO THE APPLICATION
OVERDIMENSIONED COMPONENTS TO GUARANTEE RELIABILITY AND DURABILITY
WORKING MODE SELECTION LIKE IN KOMATSU EXCAVATORS
TWO FRONT LOADER SPEEDS LIKE IN KOMATSU WHEEL LOADERS
Customer Service Department
Pag. 7 di 20

8. Diapositiva 8

Hydraulic System : Compensators
FLOW
CONTROL
P
S
FLOW CONTROL
COMPENSATION
Q=kS
P
P
Q
S
METERING
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Komatsu Utility Europe
Customer Service Department
Pag. 8 di 20

9. Diapositiva 9

Hydraulic System : Compensators
THE INNOVATIVE
SYSTEM
INSTALLED
ON THE
NEW
KOMATSU
BACKHOE
LOADERS
CONVENTIONAL SYSTEM
Flow division without pressure compensator
Flow division with
1
2
3
Flow division with
pressure compensator
1
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2
3
Customer Service Department
Pag. 9 di 20

10. Diapositiva 10

Hydraulic System : Compensators
Light load
Heavy load
PLS1
PLS1 > PLS2
PLS2
Main
spool
Pcomp
Flow
control
valve
Pressure
reducing
valve
Pressure compensation valve
Pp
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Customer Service Department
Pag. 10 di 20
Pp

11. Diapositiva 11

Hydraulic System : Compensators
2.Light load
(Compensated side)
PLS2 < PLS1
PLS1
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Komatsu Utility Europe
Customer Service Department
Pag. 11 di 20
1.Heavy load
(Compensating side)

12. Diapositiva 12

Hydraulic System : Lay Out
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Komatsu Utility Europe
Customer Service Department
Pag. 12 di 20

13. Diapositiva 13

Hydraulic System : Lay Out
Bucket movement
Low Pressure
LS Pressure
Main Pressure
PPC Pressure
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Komatsu Utility Europe
Customer Service Department
Pag. 13 di 20

14. Diapositiva 14

Hydraulic System : Lay Out
Steering system
Low Pressure
LS Pressure
Main Pressure
PPC Pressure
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Komatsu Utility Europe
Customer Service Department
Pag. 14 di 20

15. Diapositiva 15

Hydraulic System : Control Valve
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Komatsu Utility Europe
Customer Service Department
Pag. 15 di 20

16. Diapositiva 16

Hydraulic System : Control Valve
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Komatsu Utility Europe
Customer Service Department
Pag. 16 di 20

17. Diapositiva 17

Hydraulic System : Control Valve
Unloading
LS Port
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Komatsu Utility Europe
Customer Service Department
Pag. 17 di 20

18. Diapositiva 18

Hydraulic System : Control Valve
Steering priority valve
PPC priority valve
PPC self reduct. valve
LS Pressure relief valve
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Komatsu Utility Europe
Customer Service Department
Pag. 18 di 20

19. Diapositiva 19

Hydraulic System : Control Valve
Safety valve swing
Safety valve bucket
Safety valve boom
Safety relief valve
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Komatsu Utility Europe
Customer Service Department
Pag. 19 di 20

20. Diapositiva 20

Hydraulic System : Control Valve
Side shift
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Komatsu Utility Europe
Customer Service Department
Pag. 20 di 20