TM-9-2815-200-35
ENGINE, WITH CONTAINER:TURBOSUPERCHARGED, DIESEL ,FUEL INJECTION ,90-DEGREE “V” TYPE, AIR - COOLED ,12 - CYLINDER , ASSEMBLY ;MODELS AVDS-1790-2M (2815-856-4996), AVDS-1790-2A AND AVDS-1790-2AM (2815-856-9005)
TECHNICAL MANUAL; DIRECT SUPPORT, GENERAL SUPPORT AND DEPOT MAINTENANCE MANUAL INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS
TM-9-2815-200-35 - Page 55 of 779
b. Intake Manifold Heater (fig. 1-12).
(1)
The intake manifold (figs. 1-1 and 1-5)
which distributes induction air to each bank of
cylinders
is equipped
with an electrically
operated flame type intake manifold heater. The
heater is provided as an aid for cold weather
starting and cold weather operations. Operation
of the heater switch (in the vehicle operator’s
compartment) energizes the manifold heater fuel
solenoid valve, the heater ignition unit, and
spark plug for each heater simultaneously. Fuel
is hand pumped through the manifold heater fuel
filter and fuel solenoid valve and sprayed into the
intake manifold. The fuel is ignited by the spark
plug and burns in the intake manifold as the
engine is cranking, and the flame heats the
incoming air.
This flame-heated air and the
products of combustion are fed directly into the
cylinders with little heat loss. This results in an
immediate engine response, and assures com-
plete combustion at low engine rpm and at no-
load operating conditions with low ambient
temperature.
(2) The manifold heater fuel inlet solenoid
valve prevents fuel pumped by the fuel pump
assembly from entering the air intake manifold
heater unless the heater system is energized. A
manifold heater fuel return solenoid valve is
located at the rear of the engine. The valve is also
energized (opened ) when the ignition unit and
heater spark plugs are energized to permit excess
fuel to be returned to the fuel tanks. The main
fuel check valve prevents back flow of the fuel
when the purge pump in the driver’s com-
partment is actuated.
1-20.
Exhaus t
System
and
Tur -
bosupercharger
a.
The exhaust system consists of four
manifolds, one for each group of three adjacent
cylinders. The two exhaust manifolds on each
cylinder
bank are connected to the tur-
bosupercharger on their respective side of the
engine.
b.
Exhaust gases from each side of the engine
enter a turbosupercharger and are forced around
a turbine housing, radially inward, and through
a nozzle ring, toward the turbine wheel. The
exhaust gases drive the turbine wheel which in
turn, drives the compressor wheel since both
wheels are on a common shaft. Intake manifold
air enters at the center of the compressor wheel
and flows radially outward through a diffuser
section into the compressor housing. The air at
increased
velocity
then leaves
through a
tangential outlet on the outside of the compressor
housing, and enters the intake manifold.
c. The exhaust gases are expelled from the
turbosuperchargers
into the vehicle exhaust
system.
1-21. Cooling System
Note.
The key letters shown below in
parentheses refer to figure 1-8.
a. Fans.
The top of the engine is shrouded to
house two cooling fans (WW and NN) which
draw cool air from the underside of the engine,
through the cylinder fins, and discharge the hot
air vertically from the top shroud. The fans are
attached to adapters (MM) and are mounted on
shafts which are driven through a fan drive
clutch assembly (LL). The rear fan clutch is
driven by the rear fan drive shaft (GG), fan drive
bevel gearshaft (FF), and fan driven gearshaft
(HH). The front fan clutch is driven by the front
fan drive shaft (EE ) and another fan driven
gearshaft (HH).
1-17
Back to Top
