Komatsu PC200-8M0 Shop Manual page 293

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
Travel speed switch (Low
speed)
Pump capacity (%)
Motor capacity Max.
Travel speed (km/h)
a PC220-8M0, PC220LC-8M0
Travel speed switch (Low
speed)
Pump capacity (%)
Motor capacity Max.
Travel speed (km/h)
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
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
condition at least 0.5 sec., the travel
motor capacity will automatically
change, switching the travel speed
switch to Hi again.
PC200, 200LC, 220, 220LC-8M0
Lo Mi Hi
(Medium (High
speed) speed)
66 89 100
Max. Min.
3.0 4.1 5.5
Lo Mi Hi
(Medium (High
speed) speed)
77 71 100
Min. Min.
3.0 4.1 5.5
2
} at least 0.5 sec.
2
} and continues such the
PC200-8M0, PC200LC-8M0
PC220-8M0, PC220LC-8M0
3) Travel junction function
The controller detects the pilot pressure
q
when travel cotrol lever is operated, and
j udges the operator 's intention, the
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.
SEN06123-00
27
10-600