5
Power Train Electronic Control System
Smooth and soft operation
D275A-5R utilizes a newly designed power train electronic control system. The controller registers the amount of operator
control (movements of lever and operation of switches) along with machine condition signals from each sensor, to calculate
accurately the control of the transmission, steering clutches and brakes for optimal machine operation. The ease of
operation and productivity of new D275A-5R is greatly improved through these new features.
Electronic Controlled Modulation Valve (ECMV) controlled transmission
Controller automatically adjusts each clutch engagement depending on travel conditions
such as gear speed, revolution and shifting pattern. This provides smooth shockless clutch
engagement, improved component reliability, improved component life and operator ride
comfort.
Electronic Controlled Modulation Valve (ECMV) controlled steering clutches/brakes
Sensors monitor machine operating conditions, and electronically control steering clutches and brakes depending on type of
job, such as size of load during dozing, incline angle of slope or load, providing smooth and ease of operation by reducing
counter-steering on downhill travel, etc.
Auto downshift function
Controller monitors engine speed, travel gear and travel speed.
When load is applied and machine travel speed is reduced, the
controller automatically downshifts to optimum gear speed to
provide high fuel efficiency. This function provides comfortable
operation and high productivity without manual downshifting.
(This function can be cancelled with cancel switch.)
Electronic Controlled
Modulation Valve (ECMV)
Conventional modulation valve
Time
Clutch pressure
F1-R1 MODE
F1-R2 MODE
F2-R2 MODE
Press
DOWN
switch
Press
DOWN
switch
Press
UP
switch
Press
UP
switch
UP
DOWN
Heavy load
Light load
Actuated on heavy
load or steep slope
4
Palm command
electronic controlled
travel control joystick
Palm command travel joystick
provides the operator with a
relaxed posture and superb
fine control. Transmission gear
shifting is simplified with thumb
push buttons.
Full-adjustable suspension seat and travel control
console
For improved rear visibility during reverse operations, the
operator can adjust seat 15° to the right. The transmission
and steering controls move with the seat for optimum
operator comfort. The travel control console also has
adjustment fore and aft, and height. The armrest is
independently adjustable up and down, providing optimum
operation posture for all operators.
Palm command PPC
controlled blade control
joystick
Blade control joystick uses the
Proportional Pressure Control
(PPC) valve and palm
command joystick similar to the
travel control joystick.
PPC control combined with the
highly reliable Komatsu hydraulic system enables superb
fine control. (Dual tilt and pitch operation are enabled by
depressing switch with a thumb. This is available when
optional dual tilt dozer is installed.)
Fuel control dial
Engine revolution is controlled by electric signals, providing
ease of operation, eliminating maintenance of linkage and
joints.
Height adjustable blade control armrest
Blade control armrest is height adjustable without any tools
in three stages, providing the operator with firm arm
support in an ideal armrest.
Position adjustable ripper control lever
Ripper control lever position is adjustable, providing optimum
operator posture during all types of ripping operations.
MONITOR SYSTEM
Electronic controlled
steering/brake system
ECMV
ECMV
ECMV
ECMV
Auxiliary
valve
Travel
control
lever
Steering controller
Fuel
control
dial
Monitor panel
Deceleration
pedal
Transmission
controller
Engine
controller
Electronic controlled
transmission
Engine
Fuel control
valve unit
ECMV
ECMV
ECMV
ECMV
Brake pedal
potentiometer
Pitch
angle
sensor
Trans-
mission
output
speed
sensor
Auto shift
down switch
Switch
Transmission control
Transmission
control valve
Water
temp.
Engine
oil
pressure
Engine
speed
Torque converter
Komatsu’s ergonomically designed control system “PCCS” creates an operating environment with
“complete operator control”.
Left-hand joystick
Blade and ripper
control joystick
Outline of electronic control system
Human-machine Interface
P
ALM
C
OMMAND
C
ONTROL
S
YSTEM
(PCCS)
D275A
-5R
CRAWLER DOZER
D275A
-5R
C
R A W L E R
D
O Z E R
Preset travel speed function
Preset travel speed selection function is standard equipment, enabling the operator to select fore and aft travel speed from
three preset patterns; F1-R1, F1-R2 and F2-R2 by using the UP/DOWN switch. When the F1-R2 or F2-R2 preset pattern is
selected and the travel control is moved into forward or reverse, the machine travels in the preset gear range automatically.
This function reduces manual gear shifting frequency during machine operation, enabling the operator to focus on directional
and hydraulic control. Preset travel speed selection is especially helpful when used in combination with the auto-downshift
function and reduces cycle times during repeated round trip operations.
Facing front
When turned 15°
Effect of ECMV steering clutches/brake control
When dozing and turning, ECMV automatically
controls stroke ratio of steering clutches
and brakes depending on degree of
load, enabling smooth dozing
and turning.
When dozing downhill, ECMV
automatically controls steering clutches
and brakes depending on incline of
machine or degree of load, reducing
counter-steering and producing
smooth dozing operation.
