checked at regular intervals to make sure they are still
generators. They can cause overheating, electrical
tight. You must pay particular attention to the bolts used
grounds, and short circuits.
to clamp any insulation.
Electric motors and generators usually have some
type of permanent air filter. This can be wire-mesh
Electrical Connections
s c r e e n , perforated metal, or closely spaced metal
strips. These air filters should be kept clean or at least
All electrical connections should be inspected at
replaced quarterly. When the ship is in an overhaul
regular intervals to make sure they are tight. Particular
y a r d , adequate protection should be provided to
attention should be paid to terminals and terminal board
electrical motors and generators. Motors and
connections. Loose connections result in increased
generators not required to be operated during the yard
contact resistance and increased heating that may result
period should have their openings sealed to prevent
in breakdown. Use lock nuts, lock washers, or other
e n t r y of dirt and debris. Machinery required for
means to lock connections that could come loose due to
operation should have protective screens of suitable
vibration. Make sure exposed electrical connections are
filter material installed.
a d e q u a t e l y insulated to protect against water and
moisture and injury to personnel. This applies especially
Several methods are used to clean motors and
to exposed connections at terminal straps extending
generators. You should choose the cleaning method that
outside the frames of motors and generators.
is the safest and most productive for your situation. The
following list contains some of the preferred methods
Bearings
for cleaning motors and generators:
1. Wipe the motor or generator with a clean,
One of the most frequent tasks for a GSE consists
lint-free, dry rag to remove loose dust or foreign
of maintenance, troubleshooting and replacing bearings
particles. Make sure you clean the end windings, slip
in motors and generators. Bearings are designed to allow
ring insulation, connecting leads, and all the terminals.
a rotating armature or rotor to turn freely within a motor
o r generator housing. Bearings must be properly
2. Use a vacuum cleaner to remove abrasive dust,
maintained to reduce the heat caused by friction.
dirt, and particles from inaccessible parts. This method
P r e v e n t i v e maintenance of bearings consists of
is preferred over the use of compressed air because it
cleaning, lubricating, and periodic checks of bearing
lessens the chance of damage to the insulation.
wear and conditions of bearing surfaces. For a more
3. Use air pressure to blow out inaccessible areas,
detailed description of bearing maintenance, refer to
such as armature air vents. Use air pressure up to 30
GSE3/GSM/3, Volume 1, NAVEDTRA 10563, and
pounds per square inch (psi) to blow out motors and
NSTM, chapter 244.
generators of 50 horsepower (hp) or 50 kilowatts (kW).
Use air pressure up to 75 psi to blow out higher-rated
Brushes
machines.
Brushes are used in electric motors and generators
4. Use inhibited methyl chloroform to remove
to provide a passage for electrical current to an internal
grease and pasty substances consisting of oil and carbon
or external circuit. Proper maintenance practices will go
or dirt. NEVER use gasoline, benzene, petroleum ether,
far towards eliminating brushes as a frequent cause of
o r carbon tetrachloride for cleaning motors and
f a i l u r e . PMS procedures are established for the
generators.
maintenance of brushes and brush riggings. The correct
5. Motors and generators that have been wet with
grade of brush and the correct brush adjustment are
salt water should be flushed out with fresh water and
necessary to avoid trouble in motors and generators. You
t h e n dried. If possible, the machinery should be
must identify the type of brush and its manufacturer
disassembled to permit a thorough cleaning.
when replacing brushes in motors and generators. Never
mix different manufacturer's brushes or grades of
Bolts and Mechanical Fastenings
brushes from the same manufacturer. Rapid brush wear
could result from a mismatched set of brushes.
Bolts and mechanical fastenings on both the
Whenever new brushes are installed or the old
stationary and rotating members should be tightened
brushes do not fit, they should be fitted and seated.
securely when the motor or generator is assembled. The
Accurate seating of the brushes where their surfaces
b o l t s and fastenings are then checked after the
contact the collector rings (slip rings) is essential. Sand
equipment has run for a short time and thereafter
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