GMC 1989 Light Duty Truck, Руководство по ремонту, Страница: 647 / 998

SI SERIES GENERATORS 6D1 -7
N O TIC E: The ro to r m ay b e d is to rte d if th e vise is
o v e rtig h te n e d .
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Pulley nut (22).
• Insert a hex head wrench in the end of the rotor
shaft to counteract the force of rotation when
removing the pulley nut.
W asher (23).
Pulley (43).
Fan (44).
Front collar (34).
Rotor (42).
Rear collar (35).
Bearing retainer bolts (24).
Bearing retainer (37).
Bearing (32).
• Support the bearing housing when pressing out
the bearing.
INSPECTION AND REPAIR
Clean
All metal parts except the voltage regulator, rectifier
bridge, stator, rotor and bearing assem blies in a suit­
able solvent.
— Wipe or blow the parts dry.
Inspect
Brush holder for damage.
IJ J I Clean
— Brush holder. Make sure the brush pockets are
clean.
— Brushes with a soft dry cloth.
Insulating sleeves on the insulated screws for splits or
wear.
Brushes for wear. If the brushes are worn to one half
or less of their original length, replace them.
Brush leads for broken wires, corrosion or chafing.
Slip ring end bearing for grease. If the grease supply
is used up, replace the bearing. DO NOT relubricate
the bearing.
Slip ring end of the rotor shaft for overheating or scor­
ing. If the signs of overheating or scoring are present,
replace the bearing and rotor.
Drive end bearing for roughness, looseness, and seal
condition. If the condition of the bearing is doubtful,
replace it.
W indings for burned insulation. Replace the rotor or
stator if either looks burned.
• Burned insulation appears as a very dark or
blackened wiring. A strong acrid odor will be
apparent.
Terminal connectors for corrosion or breaks.
W indings on the stator for chipped insulation. If the
chipped area is small and the rest of the stator is OK,
repair the stator with insulating varnish.
Slip rings for scoring, wear or pitting.
• If the rings are dirty, clean with a 400 grain, or
finer, polishing cloth.
— Spin the rotor and hold the polishing cloth
against the slip rings until they are clean.
• If scored, worn, or pitted, true the rings in a lathe
to 0.05 mm (0.002-inch).
— Finish with 400 grain or finer polishing
cloth. Blow away all dust.
12. Rotor and stator w indings electrically as described
later under “ Electrical T ests.”
13. Generator housing for cracks, warping, or other dam ­
age.
ELECTRICAL TESTS
E xcept as stated, m ake the fo llo w in g tests w ith an
ohm meter on the low range scale.
ROTOR FIELD WINDING CHECKS (Figure 10)
The rotor may be checked electrically with a 110-volt test
lamp or an ohm meter.
Open Winding
To check for opens, connect the test lamp or ohm m eter
to each slip ring. If the lamp fails to light, or if the ohm m eter
reading is high (infinite), the winding is open.
Ground Winding
Connect a test lamp or ohm m eter from one slip ring to the
shaft. If the lamp lights, or if the reading is low, the rotor
winding is grounded.
Short Circuit or Resistance Check
The winding is checked for short-circuits or excessive
resistance by connecting a battery and am m eter in series
with the edge of the two slip rings. Note the am m eter read­
ing and refer to “ Specifications” at the end of this section.
An amm eter reading above the specified value indicates
shorted windings; a reading below the specified value indi­
cates excessive resistance. An alternate m ethod is to
check the resistance of the field by connecting an ohm m e­
ter to the two slip rings. If the resistance reading is above
the specified value the winding has excessive resistance.
Note the reading and refer to “ S pecifications” at the end of
this section.