Komatsu D61EX-24 Operation & Maintenance Manual page 243

MACHINE OPERATIONS AND CONTROLS
REMARK
• Regardless of the ambient temperature, if the starting switch (2) is turned counterclockwise from OFF posi-
tion, preheating pilot lamp (3) lights up and preheating starts. (Pre-heating continues while the starting
switch (2) is held at the left.)
For the details of the preheat time, see the table in step 5.
• While preheating is being performed, preheating pilot lamp (3) lights up to indicate that preheating is being
performed.
• If the engine does not start with the preceding operation, wait for approximately 2 minutes, and repeat steps
3 and 4.
• Urea SCR system has the function of heating system and keeping it warm to prevent freezing of DEF.
If DEF is frozen, DEF system is heated and thawed automatically after the engine starts. The devices do
not operate until DEF is thawed and supplied, but this does not indicate any abnormality.
When the ambient temperature decreases to a level where the DEF may freeze while the machine is in op-
eration, the DEF system is warmed automatically to prevent freezing. When the ambient temperature de-
creases to a level where freezing of DEF is not preventable, the devices stop automatically, but this does
not indicate any abnormality.
• If DEF freezes, thawing operation is performed automatically. Never heat DEF.
Harmful ammonia gas may be generated.
Turbo protect function
The turbo protect function protects the turbocharger by keeping the engine speed at approximately 1000 rpm or
less immediately after the engine is started.
When the turbo protect function and automatic warm-up function operate at the same time, the turbo protect
function is given priority.
• When the turbo protect function is actuated, the engine speed is held at 1000 rpm, even if the fuel control
dial is turned to a position of 1000 rpm or higher.
• When the turbo protect function is canceled, the engine speed is set to the speed for the position of the fuel
control dial.
• The relationship between the actuating time of the turbo protect function and the temperature of the engine
coolant is as shown in the table.
Coolant temperature
( °C { °F} )
Min. 10 {50}
10 to -30 {50 to -22}
-30 {-22} and below
Automatic warm-up function
The automatic warm-up function increases the idle speed to 1200 rpm to increase the engine coolant tempera-
ture quickly during operation at low temperature.
When the turbo protect function and automatic warm-up function operate at the same time, the turbo protect
function is given priority.
• When the automatic warm-up function is actuated, the engine speed is held at 1200 rpm, even if the fuel
control dial is turned to a position of 1200 rpm or lower.
However, if the fuel control dial is held at High idle (MAX) position for more than 3 seconds, the auto warm-
up function is canceled and then the engine speed can be lowered below 1200 rpm.
• The automatic warm-up function continues operation until the engine coolant temperature reaches 30 °C
{86 °F} or up to 10 minutes.
• If the decelerator/brake pedal is depressed while the automatic warm-up function is in operation, the auto-
matic warm-up function is canceled and the engine speed decreases 1200 rpm and below.
3-192
Turbo protect time (sec.)
0
Variable between 0 and 20
20
OPERATION