for a continuous display and to actuate a high
from the high-pressure air flasks. Each flask is charged
temperature audible and visual alarm. The alarm is set
at 3,000 psig from the ship's high-pressure air system.
at 205F. The second RTD supplies a signal to an
The system has sufficient capacity for 10 engine starts
indicator mounted on the LOP.
before recharging is necessary.
A differential pressure switch is located between the
The high-pressure air is reduced to 150 psig
inlet and outlet of the engine. This switch sends an alarm
through a reducing station. One start air reducing
signal to the EPCC, which will shut down the engine
station with associated piping is installed at each
upon a loss of jacket water flow.
SSDG. A pressure transducer and pressure switch are
installed in the start air piping to the engine. The
Water from the exhaust manifolds enters cored
transducer provides a signal to the EPCC to actuate
passages in the engine front cover and returns to the
an audible and visual alarm whenever the air pressure
pump suction. After leaving the engine, the flow of
drops to 100 psig. The pressure switch actuates an
jacket water is diverted between the jacket water cooler
alarm at the local alarm panel outside the SSDG
and the waste heat exchanger. (A three-way temperature
enclosure.
regulating valve in the piping system is used to control
the division of the flow.) The jacket water recombines
AIR INTAKE AND EXHAUST SYSTEM. The
after passing through one or both heat exchangers, flows
air intake and exhaust system supplies air to the
through the lube oil cooler, and back to the water pump
cylinders for combustion and scavenging. During
suction flange.
operation, the air is drawn into the blower section of
the turbocharger through an air filter, where it is
The three-way temperature regulating valve and
compressed and the temperature is increased. It is then
auxiliaries form a control circuit that diverts the jacket
delivered to the intercooler where the air temperature
water to the jacket water cooler or the waste heat
is reduced. From the intercooler, the cooled dense
exchanger, depending on the engine jacket water and
charge of air is routed to the blower intake. The blower
the waste heat exchanger freshwater outlet
further compresses the air and sends it to the air box
temperatures. The temperature regulating valve
that surrounds the cylinder liners. The air is then
assembly consists of a three-way diverting valve with
forced into the cylinders for combustion.
a reverse-acting, air-operated diaphragm actuator and
a valve positioner controlled by two temperature pilot
After combustion takes place, the exhaust valves
controllers. The pilot controllers work together to
open and the hot gases are discharged to the exhaust
direct all jacket water to the waste heat exchanger
manifold. The exhaust manifold and adapter direct the
when the outlet temperature of the waste heat fresh
exhaust gases to the turbine section of the turbocharger.
water is < 171F and that of the jacket water is
After providing the turbocharger with its driving
< 191F. When the waste heat temperature is between
medium, the hot exhaust gases are routed to a muffler
171F and 178.5F and the jacket water is between
located in the uptake space.
191F and 199F, both controllers will regulate to divide
The turbocharger consists of a radial inward flow
the flow between the jacket water cooler and the waste
turbine wheel and shaft assembly and a centrifugal
heat exchanger. If the waste heat temperature rises
compressor wheel mounted on the opposite end of the
above 178.5F or the jacket water temperature rises
turbine shaft. The turbine housing is a heat-resistant
above 199F, the affected pilot will close, shutting off
alloy casting that encloses the turbine wheel and
control air pressure to the control valve and diverting the
provides flanged exhaust gas inlet and an axial exhaust
jacket water to the required area.
gas outlet. The turbine housing is bolted to the center
Now that you have seen how the jacket water
housing. The compressor housing has an axial air inlet
cooling system works, let's look at the air systems.
and a discharge connection. It is connected to the inlet
air cleaner and to the outlet piping with a clamp
Air Systems
arrangement. The compressor housing is clamped to the
compressor end of the center housing. The turbocharger
is mounted on the exhaust manifold adapter with
The Detroit Diesel's air systems consist of the
starting air system and the intake and exhaust air
connectors.
system.
The two intercoolcrs are mounted at the rear of the
engine at the top. They are used to cool the compressed
STARTING AIR SYSTEM. The starting air
system supplies compressed air to the engine starter
air from the turbochargers. They consist of an air inlet
