Komatsu PC200-8M0, Shop Manual

Page: 293 / 1254

SEN06123-00
PC200, 200LC, 220, 220LC-8M0 10-600
27
600 Electrical system
Electrical control system
1) Pump control function during travel
q
For details, see "Engine and pump composite
control function".
2) Travel speed change function
1] Manual change with travel speed
selector switch
Switching the travel speed selector
switch from Lo to Mi and Hi causes
the pump controller to control the
pump capacity and motor capacity at
each gear speed as shown below,
switching the travel speed.
a
PC200-8M0, PC200LC-8M0
a
PC220-8M0, PC220LC-8M0
2] Automatic change by engine speed
If you adjust the engine speed to
1,500 rpm or less with the fuel control
dial,
q
The travel speed does not switch
to Hi when the machine is travel-
ing in Mi.
q
The travel speed automatically
changes to Mi when the machine
is travelling in Hi.
3] Automatic change by pump discharge
pressure
If the travel pressure is kept to 24.5
MPa {250 kg/cm
2
} at least 0.5 sec.
due to increased load during traveling
in Hi on an uphill, the travel motor
capacity automatically switches to the
medium speed (Mi) (the travel speed
switch stays at Hi).
If the machine starts traveling on level
ground or downhill during operation of
the above mentioned function and the
travel pressure goes below 14.7 MPa
{150 kg/cm
2
} and continues such the
condition at least 0.5 sec., the travel
motor capacity will automatically
change, switching the travel speed
switch to Hi again.
PC200-8M0, PC200LC-8M0
PC220-8M0, PC220LC-8M0
3) Travel junction function
q The controller detects the pilot pressure
when travel cotrol lever is operated, and
j u d ge s t h e o p e ra t o r ’s i n t e n t i o n , t h e
straight travel or turning operation.
q For straight-travel, a signal is sent to the
travel junction solenoid valve, controlling
the pump flow rate between the right and
left to be equal, to prevent travel deve-
ation and improve straight-travel ability.
q For turning operation, the signal to the
travel junction solenoid valve is shut off.
This separates the pump flow rate to the
right and left travel motors from each other
and improves the traction while turning.
Travel speed switch
Lo
(Low
speed)
Mi
(Medium
speed)
Hi
(High
speed)
Pump capacity (%) 66 89 100
Motor capacity Max. Max. Min.
Travel speed (km/h) 3.0 4.1 5.5
Travel speed switch
Lo
(Low
speed)
Mi
(Medium
speed)
Hi
(High
speed)
Pump capacity (%) 77 71 100
Motor capacity Max. Min. Min.
Travel speed (km/h) 3.0 4.1 5.5