Milton CAT 990H - Manual (Page 6)

Next Generation Modular Radiator
(NGMR) with Air-to-Air Aftercooling
System (ATAAC). In order to meet U.S.
EPA Tier 3 and EU Stage IIIa emissions
requirements. The cooling system has
been upgraded to a NGMR that utilizes
the ATAAC system to achieve lower
particulate, NOx and sound output.
The proven NGMR system is currently
used on other Cat models such as the
834H, 844H, 988H and 992G. ATAAC
technology became effective with the
834G and 988G.
NGMR is a Caterpillar ® technology that
improves serviceability and increases
cooling efficiency by 22 percent.
Ambient working temperature for
the standard 990H is 43° Celsius
(110° Fahrenheit). A high ambient
cooling package, with a 50° Celsius
(122° Fahrenheit) capacity, is available
as an attachment.
ATAAC System. Provides a separate
cooling system for the intake manifold
air complementing the engine jacket water
cooling system. The ATAAC system
routes hot compressed air from the turbo
and cools it with a single pass, air-to-air
aluminum heat exchanger. The cooled
compressed air is then delivered to the
engine intake manifold. Providing the
engine with cool compressed air greatly
reduces the emissions produced, meeting
Tier 3 requirements for a cleaner
environment.
Separated Cooling System. The C27
engine with MEUI has a separated cooling
system which isolates the NGMR and
demand fan from the engine compartment.
The cooling system is isolated from the
engine compartment by a shield allowing
the radiator to receive outside ambient air
through the side and top vents at a much
lower temperature than the hot air from
the engine compartment. This improves
the system’s efficiency and allows the
radiator size to be decreased and the rear
hood to be sloped, improving the rear
viewing area. Also, sound levels are
reduced due to the lower fan speed
of a more efficient cooling system.
Serviceability. Is a key feature of NGMR.
Tubes are welded to a large, thick header,
providing the strength of the tube-to-
header joint that reduces the possibility
of coolant leaks. The NGMR modular
core design allows removal of a single
core without removing the entire radiator
– reducing downtime through ease of
serviceability. Replacing the individual
core also reduces repair costs.
Two-Pass System. Is a NGMR feature for
increased cooling capacity. Coolant travels
from the engine to the fan side of the
bottom tank, up the fan side of each core,
over the top, down the engine side of the
core, into the engine side of the bottom
tank and back to the engine. The improved
flow pattern allows the coolant to pass
through the radiator twice for better
cooling. The NGMR design improves
serviceability, reduces downtime and
increases cooling capability.
6
Cooling System
Works with the engine to meet emissions standards as well as improve serviceability
and reduce downtime.