Hydraulic System : Main
Hydraulic System : Main PrinciplePrinciple
FLOW:
FLOW:
de
dete
terr mi
mi n
ne
es
s th
the
e speed
speed
of th
of th e
e wor
work e
k equi
qui pme
pment.
nt.
Speed of work
Speed of work equipment is determined by the equipment is determined by the amount of pump flow.amount of pump flow. Greater the pump flow the greater the speed.
Greater the pump flow the greater the speed. Lesser pump flow creates slower speeds. Lesser pump flow creates slower speeds.
Pump flow rate is determined by the pump swash
Pump flow rate is determined by the pump swash plate angleplate angle and rpm.
and rpm.
PRESSURE:
PRESSURE:
de
dete
terr mi
mi nes
nes th
the
e amou
amoun
nt of
t of force
force
the
th
e wor
work
k e
equi
qui pme
pment
nt ca
can
n e
exe
xerr t.
t.
Pressure is determined by resistance
Pressure is determined by resistance up until maximum relief pressure is reached.up until maximum relief pressure is reached. Resistance can come in two forms:
Resistance can come in two forms: Flow rate and size of
Flow rate and size of port the oil must pass through.port the oil must pass through. Amount of resistance from the
Amount of resistance from the work equipment.work equipment. When maximum reli
When maximum relief pressure is reached the machine cannot exert ef pressure is reached the machine cannot exert any more force and the workany more force and the work equipment stops.
Hydraulic System : Main
Hydraulic System : Main PrinciplesPrinciples
As the pump
As the pump swash
swash
plate angle incre
plate angle incre
ases
ases
more fluid can fill each
more fluid can fill each
chamber increasing the
chamber increasing the
flow.
flow.
As the pump
As the pump swash
swash
plate angle decr
plate angle decr
eases
eases
less fluid can fill each
less fluid can fill each
chamber decreasing
chamber decreasing
flow.
flow.
When the pump
When the pump rotation
rotation
speed increases
speed increases
, the
, the
pump flow increases.
pump flow increases.
This is directly effected
This is directly effected
by engine rpm.
by engine rpm.
When the pump
When the pump rotation
rotation
speed decreases
speed decreases
, the
, the
pump flow decreases.
pump flow decreases.
This is directly effected
This is directly effected
by engine rpm.
by engine rpm.
Pump RPM
Pump RPM
This is valid also for the gear pump
This is valid also for the gear pump
not represented here
not represented here
Pump Swash
Hydraulic System :
Hydraulic System : Flow/Pressure RelationshiFlow/Pressure Relationshipp
Th
Thee re
rela
lati
tio
on
nsh
ship
ip b
bet
etw
wee
een
n fflo
low
w an
and
d p
pre
ress
ssu
ure
re is
is sh
sho
ow
wn
n in
in th
thee H
Hyd
ydrrau
auli
licc O
Out
utp
put
ut Cu
Currve
ve..
W
Wiitth
h aallll h
hy
yd
drraau
ulliicc eeq
qu
uiip
pm
meen
ntt tth
hee rreellaattiio
on
nssh
hiip
p b
beettw
weeeen
n ffllo
ow
w aan
nd
d p
prreessssu
urree iiss iin
nv
veerrsseelly
y
proportional:
proportional: as
as pressure
pressure increases
increases flow
flow decreases
decreases and
and as
as pressure
pressure decreases
decreases flow
flow
increases.
increases.
Flow
Flow
(Q)
(Q)
Pressure (P)
Pressure (P)
Q
Q
x
x
P
P
Hydr. POWER is constant
Hydr. POWER is constant
=
=
Hydraulic System : Variable Displacement Pump Hydraulic System : Variable Displacement Pump
BASIC PRINCIPLE
BASIC PRINCIPLE
1.
1. Co
Cont
ntro
rol o
l of p
f pum
ump s
p swa
wash
sh pl
plat
ate a
e ang
ngle
le
The
The pump
pump swash
swash plate
plate angle
angle (pump
(pump
discharge amount) is controlled so that LS
discharge amount) is controlled so that LS
differentia
differential
l pressure
pressure
PLS
PLS (the
(the difference
difference
between pump (discharge) pressure
between pump (discharge) pressure PP
PP and
and
control valve outlet port LS pressure
control valve outlet port LS pressure PLS
PLS))
load pressure of actuator) is constant.
load pressure of actuator) is constant.
(LS pressure
(LS pressure
PLS
PLS=Pump discharge
=Pump discharge
pressure
P P u u m m p p D D i i s s c c h h a a r r g g e e Q Q ( ( o o r r P P u u m m p p D D i i s s p p l l a a c c e e m m e e n n t t D D ) ) LS
LS differential differential Pressure Pressure PLSPLS
<If
<If the
the PLS
PLS is
is lower
lower than
than the
the PLS
PLS set
set
pressure>
pressure>
Hydraulic System : Variable Displacement Pump Hydraulic System : Variable Displacement Pump
Hydraulic System : Speed Up Hydraulic System : Speed Up
•
• POWER MODE POWER MODE & SPEED UP ADVA& SPEED UP ADVANTAGES:NTAGES:
–
– PERFECT CONTROL OF THE PERFECT CONTROL OF THE AVAILABLE POWER AVAILABLE POWER –
– NO ENERGY LOSS AND COSTS SAVINGNO ENERGY LOSS AND COSTS SAVING –
– SELF-ADJUSTMENT SYSTEM ACCORDING TO THE SELF-ADJUSTMENT SYSTEM ACCORDING TO THE APPLICATIONAPPLICATION –
– OVERDIMENSIONED COMPONENTS TO GUARANTEE RELIABILITY AND OVERDIMENSIONED COMPONENTS TO GUARANTEE RELIABILITY AND DURABILITYDURABILITY –
– WORKING MODE SELECTION LIKE IN KOMATSU EXCAVATORSWORKING MODE SELECTION LIKE IN KOMATSU EXCAVATORS –
Hydraulic System : Compensators Hydraulic System : Compensators
Q = k S
Q = k S
P
P
P
P
S
S
FLOW FLOW CONTROL CONTROL
P
P
S
S
FLOW CONTROL FLOW CONTROLQ
Q
METERING METERING COMPENSATION COMPENSATIONFlow division without pressure compensator Flow division without pressure compensator
2
2
3
3
1
1
CONVENTIONAL SYSTEM CONVENTIONAL SYSTEMFlow division with Flow division with pressure compensator pressure compensator
2
2
3
3
1
1
Flow division with
Flow division with
THE INNOVATIVE THE INNOVATIVE SYSTEM SYSTEM INSTALLED INSTALLED ON THE ON THE NEW NEW KOMATSU KOMATSU BACKHOE BACKHOE LOADERS LOADERS Hydraulic System : Compensators
Heavy load
Heavy load Light loadLight load
Flow Flow control control valve valve Pressure Pressure reducing reducing valve valve Main Main spool spool
Pressure compensation valve Pressure compensation valve
Pcomp Pcomp Pp Pp Pp Pp PLS2 PLS2 PLS1 PLS1
PLS1
PLS1
>
>
PLS2
PLS2
Hydraulic System : Compensators Hydraulic System : Compensators
2.Light load
2.Light load
(Compensat
(Compensated
ed side)
side)
1.Heavy load
1.Heavy load
(Compensating side)
(Compensating side)
PLS2
PLS2
< PLS1
< PLS1
PLS1
PLS1
Hydraulic System : Compensators Hydraulic System : Compensators
Hydraulic System : Lay Out Hydraulic System : Lay Out
Komatsu Utility Europe
Customer Service Department Pag. 13 di 20 WETT001304 Bucket movement LS Pressure Low Pressure Main Pressure PPC Pressure Hydraulic System : Lay Out
Steering system Steering system LS Pressure LS Pressure Low Pressure Low Pressure Main Pressure Main Pressure PPC Pressure PPC Pressure
Hydraulic System : Lay Out Hydraulic System : Lay Out
Hydraulic System : Control Valve Hydraulic System : Control Valve
Hydraulic System : Control Valve Hydraulic System : Control Valve
Unloading
Unloading
LS Port
LS Port
Hydraulic System : Control Valve Hydraulic System : Control Valve
LS Pressure relief valve
LS Pressure relief valve
Steering priority valve
Steering priority valve
PPC priority valve
PPC priority valve
PPC self reduct. valve
PPC self reduct. valve
Hydraulic System : Control Valve Hydraulic System : Control Valve
Safety relief valve
Safety relief valve
Safety valve bucket
Safety valve bucket
Safety valve boom
Safety valve boom
Safety valve swing
Safety valve swing
Hydraulic System : Control Valve Hydraulic System : Control Valve
Side shift
Side shift
Hydraulic System : Control Valve Hydraulic System : Control Valve