TM 55-2815-574-24
0003
AIR INDUCTION SYSTEM - Continued
Turbochargers
The T18A40 model turbocharger is designed to increase the over all efficiency of the engine. Power to drive the
turbocharger is extracted from the waste energy in the engine exhaust gas. The turbocharger consists of a radial
inward flow turbine wheel and shaft, a centrifugal compressor wheel and a center housing which serves to
support the rotating assembly, bearings, seals, turbine housing, and compressor housing. The center housing has
connections for oil inlet and oil outlet fittings.
Figure 2. Air Induction System.
The turbocharger is mounted on the exhaust outlet flange of the engine exhaust manifold. After the engine is
started, the exhaust gases flowing from the engine and through the turbine housing cause the turbine wheel and
shaft to rotate. The gases are discharged into the atmosphere after passing through the turbine housing. The
compressor wheel, which is mounted on the opposite end of the turbine wheel shaft, rotates with the turbine
wheel. The compressor wheel draws in fresh air, compresses it and delivers high pressure air through the engine
blower to the engine cylinders. During operation, the turbocharger responds to the engine load demands by
reacting to the flow of the engine exhaust gases. As the engine power output increases or decreases, the
turbocharger responds to the engine's demand to deliver the required amount of air under all conditions. An after
cooler is used to cool the air going into the engine after it passes through both the turbocharger and
engine blower.
