REMOVAL AND REPLACEMENT OF COM-
REMOVAL AND REPLACEMENT OF COM-
PONENTS. If required, all of the components in the
PONENTS. Except for the generator itself, all of the
cooling system can be removed and replaced by ship's
support components can be removed and replaced by
personnel. Except for the relief valve, the cooling water
ship's personnel. Even generator bearing and seal
pump will probably be removed, replaced, or rebuilt
replacement (sometimes with outside assistance) can be
more than any other system component. The primary
performed by ship's personnel. But, because system
reason for pump disassemble y or removal will be because
reliability is high, your maintenance may be limited to
of a faulty mechanical seal.
the removal and replacement of oil filters for quite some
time.
Reduction Gear Assembly
Cooling System
All of the GTGSs that we have discussed throughout
Like the oil system, the proper operation of the
this chapter use some type of a reduction gear assembly.
cooling system is vital to the overall performance of the
These assemblies are used to reduce the high speeds of
generator. However, similar to the oil system, a
the turbine to a workable speed used to turn the
generator/air/seawater cooling system is used on all of
generator. For example, the generator on a DD-963
the generator sets except the APU found on the
class ship requires only 1,800 rpm to produce its rated
LCAC-class ships and the SSPU found on the
output. This means the 13,821 rpm speed of the turbine
PHM-class ships.
must be reduced by an approximate ratio of 7.67 to 1.
The generator's cooling system plays a multiple
The proper operation and care of these reduction
role. On the larger GTGSs, the cooling system will
gears will play a vital role in the overall performance of
supply cooling water through three coolers. For
the generating plant. Without the reduction gear, the
example, the normal cooling water flow path on a
generator would be inoperable.
DD-963 with proper valve alignment is from (1)
In this section we will discuss how to maintain,
generator cooling water pump, (2) a strainer, (3) the
troubleshoot, and repair this very vital piece of
generator air cooler, (4) the generator oil cooler, and then
to (5) the reduction gear and engine oil cooler before it
equipment and its support components. However, we
is discharged overboard.
will only discuss the most prominent type of reduction
gear. These units are installed on the CG-, DD-, and
TESTS AND INSPECTIONS. As the GSM, you
DDG-993 class ships.
will be responsible for all tests and inspections for the
cooling water system. There are very few electrical
TESTS AND INSPECTIONS. Testing is
components installed in this system. In fact, the primary
normally limited to the reduction gear's lubricating oil
and some alarm circuits. On the other hand, inspections
electrical component is the pressure switch. This switch
on a DD-963 class ship, for example, controls the flow
are constantly performed. Inspections vary in
of emergency cooling water if the normal pressure is
complexity from the normal routine or visual
lost. For the most part, the only tests you will need to
inspections performed while the unit is operating to the
perform will be operational checks on the cooling water
complicated task of opening the gear casing to inspect
pump and the emergency cooling water system.
gear teeth wear and high-speed pinion axial thrust.
Remember, even though this reduction gear is part of
Inspections will normally be performed as part of
the generator, an internal inspection must be treated in
the watch routine. For the cooling water system, even
the same manner as if you were inspecting the main
though water is not flammable, a leak, depending on its
reduction gear.
location, can be extremely damaging. For example, just
like in the oil system, a leak inside the generator can
There are some other inspections that you will
damage components and even cause a fire. The PMS
probably be required to perform. These inspections are
will also require the cleaning and inspection of all of the
performed on the reduction gear support components,
generator's coolers.
such as the turbine starter, power take off (PTO) shaft,
and reduction gear to generator drive shaft.
TROUBLESHOOTING. The troubleshooting
Turbine Starter. The turbine starter is probably
procedures you should perform were described in the
section on high oil or bearing temperatures. Also,
the one support component you will inspect the most
frequently. You will normally check the turbine starter
remember always to use an approved technical
reference.
for oil leaks, diffuser vane wear, and drive gear
