Komatsu D37EX-24 Operation & Maintenance Manual page 212

MACHINE OPERATIONS AND CONTROLS
REMARK
• Regardless of the ambient temperature, if the key in starting switch (2) is turned counterclockwise from
OFF position, the preheating pilot lamp lights up and preheating starts. (Preheating continues while the
starting switch (2) is held at the left.)
For the preheating time, see the table in step 5.
• While preheating is being performed, the preheating pilot lamp lights up to indicate that the preheating is
being performed.
• If the engine does not start with the preceding operation, wait for approximately 2 minutes, and repeat the
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, the DEF system is automatically heated to thaw DEF after the engine is started. The devi-
ces 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 DEF may freeze while the machine is in opera-
tion, the DEF system is warmed automatically to prevent freezing. When the ambient temperature decrea-
ses 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 the DEF.
Harmful ammonia gas may be generated.
Turbo protect function
The turbo protect function protects the turbocharger by keeping the engine speed at approximately 1075 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 1075 rpm, even if the fuel control
dial is turned to a position of 1075 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)
10 or more
10 to -30
-30 or less
Automatic warm-up function
The automatic warm-up function increases the idle speed to 1200 rpm or more to increase the engine coolant
temperature 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 less.
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 to 1200 rpm or less.
• The automatic warm-up function continues operation until the engine coolant temperature reaches 30 °C 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 to 1200 rpm or less.
3-154
Turbo protect time (sec.)
0
Variable between 0 and 20
20
OPERATION