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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.

(3)

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

(4)

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

Hydr. POWER is constant

Hydr. POWER is constant

=

=

(5)

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

(6)

   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

(7)

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  – 

(8)

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 CONTROL

Q

Q

METERING METERING COMPENSATION COMPENSATION

(9)

Flow division without pressure compensator  Flow division without pressure compensator 

2

2

3

3

1

1

CONVENTIONAL SYSTEM CONVENTIONAL SYSTEM

Flow 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

(10)

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

(11)

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

(12)

Hydraulic System : Lay Out Hydraulic System : Lay Out

(13)

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

(14)

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

(15)

Hydraulic System : Control Valve Hydraulic System : Control Valve

(16)

Hydraulic System : Control Valve Hydraulic System : Control Valve

(17)

Unloading

Unloading

LS Port

LS Port

Hydraulic System : Control Valve Hydraulic System : Control Valve

(18)

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

(19)

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

(20)

Side shift

Side shift

Hydraulic System : Control Valve Hydraulic System : Control Valve

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