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TM 5-685/NAVFAC MO-912
tectors and install on engine. Tighten to proper
air at about 25 psi monthly. Check brushes for wear
and indications of arcing and chattering monthly.
(d) External inspection. Inspect engine
Check condition of slip rings. Refer to manufactur-
tubes, hoses, tube/hose fittings, electrical assem-
er's instructions.
blies and connectors for security, and overheating
(g) Static exciters. Verify that the equipment
and damage due to leakage. Perform inlet and ex-
is clean and free from dirt and moisture. Verify that
haust inspection as described previously. Check
all connections are tight. Check connections for cor-
standoffs, brackets and struts for looseness, cracks,
rosion and clean as required.
and damage. Check ignition exciter, igniter plugs
b. Long-term. Long-term checklists for genera-
tors and exciters.
and leads for damage, overheating and security.
Check mechanical control for signs of excessive
(1) General comments. The following tasks
wear, damage and security. Check fuel manifold for
should be performed annually unless otherwise
leaks, signs of damage and security. Check for rust
noted, following performance of short-term checks.
and/or corrosion.
(2) Checklist and schedule.
d. Long-term (gas turbines). Long-term checks
(a) Coupling Lubrication. Drain lubricant,
usually affect interior areas of the engine and are
disassemble and clean the coupling annually or
seldom performed in the field. Repairs, if necessary,
whenever necessary. Reassemble, using new gas-
may involve changes in component balance relation-
kets and fresh lubricant. Refer to manufacturer's
ships and should be performed at the designated
instructions for flexible coupling.
overhaul location. Refer to the manufacturer's lit-
(b) Brush replacement. When brushes have
erature for information.
worn to half their original length, replace, seat
properly and adjust brush rigging tension from 2.5
7-3. Generators and exciters.
to 3.6 psi on brush riding surface. Repair and re-
Routine maintenance instructions for generators
place damaged or worn brush rigging parts. Refer to
and exciters consist of short- and long-term check-
manufacturer's instructions.
lists for rotating and static type equipment.
(c) Brush electrolysis. Electrolytic action can
a. Short- term. Short-term checklists for genera-
occur at collector ring surfaces. This action forms a
tors and exciters.
greenish coating (verdigris) on brass, bronze or cop-
(1) General comments. Before performing any
per. Effects of this action can be reduced or elimi-
tasks required by the following checklist, review the
nated by reversing the polarity annually or as re-
station log sheets, related records and the manufac-
quired. Refer to manufacturer's instructions.
turer's recommendations.
(d) Commutator and collector rings. Clean
(2) Checklist .
commutator and collector rings with vacuum. Clean
(a) Air screens or filters. Air screens or filters
oil film and dirt with approved solvent. Dry with
should be changed when the air flow is restricted
compressed air at about 25 psi. Check for rough-
enough to increase generator operating tempera-
ness, hard spots and out-of-round condition. Service
ture. Refer to manufacturer's literature.
commutator and collector rings as necessary follow-
(b) Exciter coupling (if applicable). When the
ing manufacturer's instructions.
generator unit is shut down prior to operation, wipe
(e) Rotor winding. Rotor maintenance begins
off excess lubrication from the coupling to prevent
with measuring and recording the insulation resis-
tance before the unit is placed in service. Refer to
(c) Coupling Leaks and alignment. When the
manufacturer's literature for instructions. The rotor
generator has been shut down, check for lubrication
should be thoroughly cleaned annually and in-
leaks and tightness of coupling. Note ahy evidence
spected as follows: Check the damper winding for
of improper alignment and correct if necessary.
loose bars and the connection of each bar to its ring
segment. Check the joints in the ring segments be-
(d) Axial position. Check axial position of the
prime mover, generator and exciter shafts for cor-
tween poles. Refer to manufacturer's instructions.
rect alignment and angularity.
Check clearance per manufacturer's specifications
between blower and coils. Check the field coils for
(e) Bearings. Lubrication of generator and
exciter bearings is required. Refer to manufactur-
movement and separation. Clean dirt and oil from
er's literature for instructions for pressure and
winding and air passages. Check condition of turn-
nonpressure lubricated bearings.
to-turn insulation on strap field coils. Verify condi-
(f) Rotary exciters. Brushes and brush rig-
tion of ground insulation on pole pieces. Check all
ging. Remove carbon dust from collector ring and
connections between field coils and lead-out connec-
tions to collector rings. Measure and record insula-
commutator with vacuum and dry with compressed

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