TM 9-6115-730-24
0003
AIR INLET AND EXHAUST SYSTEM - Continued
The components of the air inlet and exhaust system control the quality of the air that is available for combustion.
These components also control the amount of the air that is available for combustion. Inlet air is pulled through
the air cleaner. The inlet air is then compressed and heated by the compressor wheel of turbocharger to about
150C (300F). The inlet air is then pushed through the air-to-air aftercooler core and the inlet air is moved to air
inlet where the temperature about 110F (43C). Cooling the inlet air increases the combustion efficiency which
lowers fuel consumption and increases horsepower output. The aftercooler core is a separate cooler core
installed above the standard core of the engine radiator. The engine fan moves air at ambient temperature across
the aftercooler core to cool the turbocharged inlet air. From the aftercooler core the air is forced into the cylinder
head to fill the inlet ports. The inlet valves control air flow from the inlet port into the cylinder. There are two inlet
valves and two exhaust valves for each cylinder. Inlet valves open when the piston moves down on the inlet
stroke to pull air into the cylinder. The inlet valves close and the piston begins to move up on the
compression stroke. The air in the cylinder is compressed and fuel is injected into the cylinder. The fuel mixes
with the air and combustion starts. During the power stroke, the combustion force pushes the piston downward.
Then the piston moves upward in the exhaust stroke. During the exhaust stroke, the exhaust valve opens, and the
exhaust gases are pushed through the exhaust port into the exhaust manifold. After the piston completes the
exhaust stroke, the exhaust valves close and the cycle starts again. Exhaust gases from exhaust manifold enter
the turbine side of turbocharger to turn the turbine wheel. The turbine wheel is connected to a shaft that drives the
compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet pipe, the muffler and
the exhaust stack.
Turbocharger
The turbocharger is installed on the center section of the exhaust manifold. All the exhaust gases from the engine
go through the turbocharger. The compressor side of the turbocharger is connected to the aftercooler by pipe. The
exhaust gases go into the turbine housing through the exhaust inlet. The exhaust gases spin the blades of a
turbine wheel connected by a shaft to a compressor wheel. The rotation of the compressor wheel pulls clean air
from the air filters through the compressor housing air inlet to compress the inlet air. Air compression increases
engine power by allowing the engine to burn more air and more fuel during combustion. When the load on the
engine increases, more fuel is injected into the cylinders producing more exhaust gases to increase the
turbocharger speed. As the compressor wheel turns faster, more air is forced into the cylinders. The increased flow
of air gives the engine more power by allowing the engine to burn the additional fuel with greater efficiency. The
turbocharger uses engine oil under pressure for lubrication. The oil comes in through an oil inlet port, lubricates
turbocharger bearings, and returns through an outlet port to the engine lubrication system.
Ether Starting Aid
The ECM uses the coolant temperature sensor signal to determine if ether should be injected. Ether will be
injected if the coolant temperature is between -40F and 50F (-40C and 10C) and engine rpm is between 30
and 1500 rpm. The time duration of the ether injection is a linear function of the temperature. The shortest
injection duration (15 seconds) is at the highest temperature and the longest duration (130 seconds) is at the
coldest temperature.
AC POWER OUTPUT
The AC output system (Figure 7) consists primarily of the AC generator, the output load terminal board, the
voltage reconnection terminal board, the main load contactor and the AC CIRCUIT INTERRUPTER switch on the
EMCP. Power created by the AC generator is supplied through the voltage reconnection terminal board and the
main load contactor to the output load terminals on the output load terminal board. The voltage reconnection
terminal board allows configuration of the generator set for 120/208 volt connections or 240/416 volt connections.
The DVR and GSC must be reprogrammed for voltage changes. The AC CIRCUIT INTERRUPTER switch
located on the EMCP closes and opens the main load contactor. This enables or interrupts the power flow
between the voltage reconnection terminal board and the output load terminals. The main load contactor is also
opened automatically during any of the specified set faults. The Digital Voltage Regulator (DVR) module in the
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