Figure 5-7.-Cross-sectional view of LSB oil seals.
procedures provided in the manufacturer's technical
The procedure for seal installation is usually
manual.
included in the package containing the seal. If the
instruction sheet is missing, you can find the
MAIN THRUST BEARING. Even though seal
installment procedure in the NAVSEA technical
manual for the model of the line shaft bearing
replacement can be and has been accomplished by
installed on your ship. A couple of key points for you
ship's force personnel, many engineer officers prefer
to remember are (1) make sure you use only an
to have an outside activity make the repair. The
approved adhesive to join the butt ends of the seal
reason for this is because the bearing cap must be
together and that you pack the space between the two
removed. It is extremely heavy and awkward. Few
seal faces as described in figure 5-7, and (2) make
ships have the necessary rigging experience to handle
sure you properly space the seal split lines.
this piece.
BULKHEAD SEAL. The bulkhead seal is
Removing the bearing cap is very dangerous. The
cap must be properly rigged for lifting. If, because of
another component that can easily be maintained by
limited space, it cannot be moved clear of the working
ship's force personnel. Because the bulkhead seal
area, it could possibly be left hanging directly over
does not support the shaft, virtually every part of the
your head while you arc working on the seal. Because
seal assembly can be removed and replaced without
of these potential safety hazards, make sure all
disturbing the shaft alignment. Normal wear and
precautions and instructions are followed to the
tear will require periodic replacement of the sealing
letter.
rings and garter springs. Sometimes, as the result of
an inspection, the replacement of the compression
SUMMARY
springs or the sealing discs may be necessary. One
key point to remember: Always handle the sealing
In this chapter, we have provided you with an
rings with care. These rings are made of carbon and
overview of the propulsion plants systems and drive
they can be damaged or broken easily.
train equipment and systems used on gas turbine-
powered ships. We discussed some ways in which you
STERN TUBE SEAL. The replacement of the
can properly operate and use your ship's propulsion
stern tube seal assembly can be accomplished by the
plant. If you properly maintain your propulsion plant
ship's force if the ship has all the tools required to
and its equipment, the plant will provide your ship
perform the job. The person assigned to perform this
with a high level of efficient service. With the
procedure must be experienced. Because a seal must
information provided in this chapter and the
be placed around the shaft at the hull penetration
recommended technical publications, you should
point, a qualified diver is necessary. Once all of these
become a more effective gas turbine systems
precautions are taken, seal replacement can
technician.
commence. Always, you should carefully follow the
