375, 375H, 400HH, 425, 425H T4F User Manual 2: Description
02250223-036 R01
Subject to EAR, ECCN EAR99 and related export control restrictions. 33
2.13 Electrical system, functional
description
The electrical system consists of the basic electrical ele-
ments required to operate the compressor and also has a
system feature
that automatically shuts down the com-
pressor when a malfunction occurs. The system’s com-
ponents include: an engine starter, battery, alternator/
volt
age re
gulator, and a fuel solenoid. It also has a sepa-
rator tank temperature switch that will shut the compres-
sor down
if the compressor temperature exceeds 250°F
(121°C). The single axl
e controller will shut the compres-
sor down if the engine speed falls below 1100 rpm and a
low fuel level switch sh
uts down the engine when fuel
level is low to prevent running the engine dry (out of fuel).
The engine is also equipped with an ECM (electronic
control module).
2.14 Aftercooled and filtered air
system, functional description
Refer to Figure 2-3. The purpose of the aftercooled sys-
tem is to operate the air compressor in conditions when
compre
ssed air temperature is required to be within 20°
to 25°F (13° to 17°C) of the ambient temperature.
A selector valve is provided on all aftercooled compres-
sors. Choosing the aftercooled air completely forces the
airflow from
the receiver tank to the aftercooler. The
ambient air which is drawn through the aftercooler by the
engine fan, cools the compressed air as it passes
through the aftercooler core. Cooled air enters the mois-
ture separator where condensation is removed from the
coo
ler air
and discharged. This condensate does carry
some oil and it should be disposed of properly in accor-
dance with local regulations.
From the moisture separator the air enters the (optional)
first stage filter
. Particles and additional water are
removed from the first stage filter. The condensate
should be drained and stored in a suitable container.
From the first stage filter, the air enters the (optional) sec-
ond stage filter. This filter removes s
maller pa
rticles and
any additional water. The condensate should be drained
and stored in a suitable container. Upon compressor
shutdown, the filters will drain to clear the condensate
from the system. This will prevent freezing in cold condi-
tions.
2.15 Engine exhaust aftertreatment,
functional description
This Caterpillar engine uses a diesel oxidation catalyst
(DOC) and selective catalytic reduction (SCR).
NOTE
The aftercooler system should not be operated
when the ambient temperature is below 32°F
(0°C). To operate in the non-aftercooled mode
close the aftercooler selector valve completely.
WARNING
Do not come into contact with engine exhaust
gases. These gases are hot.
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