Alternator Nomenclature - Piper PA-24 Comanche Service Manual

PIPER COMANCHE SERVICE MANL:AL
371
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FIGl'RE 9-27n. BRl'SH INSTALLATION
FIGURE '·270.
INTER~AL WIRI~G
DIAGRAM
9-ft Ij. Precautions. The following precautions are to be observed when testing or servicing the clcctrica l
svstern.
. a. Disconnect the battery before connecting or disconnecting test instruments (except \ oltmetcr ) or
before
rernov
ing or replacing any unit or wiring. Accidental grounding or shorting at the regulator. altl'rnat.
ammeter or accessories. will cause severe damage to the units and or wiring.
b. The alternator must not be operated on open circuit with the rotor winding energized.
c. Do not attempt to polarize the alternator.
~o
polarization is required. Any attempt to do so
may
result in damage to the alternator. regulator or circuits.
d. Grounding of the alternator output terminal may damage the alternator and or circuit and
components.
e. Reversed battery connections may damage the rectifiers. wiring or other components of the
charging system. Battery polarity should be checked with a voltmeter before connecting the battery. Most
aircraft are negative ground.
f. If a booster battery or fast charger is used. its polarity must be connected correctly to prevent
damage
to
the electrical system components.
9-6 I k. Alternator l'lomenclature.
a. Bearings: These units have a sealed ball bearing at the drive end and a two-piece roller bearing at
the slip ring end. The inner race is pressed onto the rotor shaft and the rest of the bearing is in the slip ring end
head. When the unit is assembled. the inner race aligns with the bearing. When the bearing is replaced. the new
inner race must be installed on the rotor shaft.
b. Lubrication; The slip ring end bearing should be lubricated whenever the alternator
i~
dis-
assembled. The bearing should be thoroughly cleaned and repacked with Shell Alvania !\o. 1 or an equivalent
bearing lubricant. The cavity behind the bearing should be packed one-third to one-half full
~
ith the same
lubricant.
c. Brushes: These units have a separate brush holder assembly that is installed after the
alternator has been assembled. The brush holder has a small hole that intersects the brush
ISSl'ED: 8/18/72
3C4
ELECTRICAL SYSTE'