Torsional Vibration. Torsional vibration
will
be generated
in
all rotating shaft systems to some
degree.
In
some cases, the amplitude
of
these vibrations at critical speeds may cause damage to either
the generator, its driver,
or
both.
It
is
therefore necessary to examine the torsional vibration effect on
the entire rotating system.
It
is the responsibility
of
the generator set assembler to assure the
torsional compatibility
of
the generator and its driver. Marathon
will
supply upon request drawings
showing
all
pertinent shaft dimensions, coup.ling details, rotor weights, locations, and inertias for the
customer to forward to the engine manufacturer for analysis.
WARNING
DISABLE
OR
RENDER
INOPERATIVE
ANY ENGINE
CRANKING
DEVICES
BEFORE
ATTEMPTING
TO
INSTALL
OR
SERVICE
THIS UNIT.
FOR
ELECTRIC
START
SETS,
DISCONNECT
THE
CRANKING
BATTERY.
WARNING
NEVER
"BAR
OVER"
THE
ENGINE-GENERATOR
SET
USING
THE
GENERATOR'S
FAN AS A
FULCRUM.
FAN
MATERIAL
IS
LIGHT
WEIGHT
ALUMINUM
AND
NOT
DESIGNED
FOR
THIS
PURPOSE.
BARRING
OVER
THE
SET
WITH
THE
FAN
COULD
DAMAGE
THE
FAN AND
RESULT
IN
INJURY
TO
PERSONNEL
OR
DAMAGE
TO
THE
EQUIPMENT.
Grade 8 place bolts and hardened washers are recommended to mount the drive discs to the flywheel.
DO
NOT
USE
SPLIT
TYPE
LOCK
WASHERS. Split lock washers when biting into the drive
discs
will
cause stress risers, and may result
in
the discs fracturing.
End play
Test
Procedure. After the generator has been assembled to the prime mover, check for
endplay.
Using a suitabl.e lever, force the engine flywheel forward so that the crankshaft
is
pressed
against its thrust bearing. When force
is
released, the engine crankshaft should remain
in
this
position. Apply force
in
the opposite direction and observe if the crankshaft again remains stationary.
Refer to the engine manual for proper
or
recommended end
play.
If
the crankshaft springs away from
either thrust bearing,
it
is
an indication that the generator shaft
is
not moving freely
in
the assembly,
and normal life
of
the thrust bearing could be impaired. Probable causes
ohhis
problem are:
l. Improper
"G" dimension
on
either the engine or generator. The generator bearing may be
bottoming out
in
the bearing bracket.
2.
Improper seating
of
drive discs
in
the flywheel resulting
in
shaft misalignment.
3. Improper mating
of
generator frame to engine flywheel housing resulting
in
misalignment.
CAUTION
DO
NOT
APPLY
FORCE
TO
THE
GENERATOR
FAN
TO
CONDUCT
AN
END
PLAY
TEST. FAN
MATERIAL
IS
LIGHT
WEIGHT
ALUMINUM AND
NOT
DESIGNED
FOR
THIS
PURPOSE.
APPLYING
SUFFICIENT
FORCE
TO
THE
FAN
TO
MOVE
THE
ENTIRE
SET
ROTATING
ASSEMBLY
COULD DAMAGE
THE
FAN, AND
RESULT
IN
INJURY
TO
PERSONNEL
5
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