Piper COMANCHE PA-24-180 Service Manual page 574

371
PIPER COMANCHE SERVICE MANUAL
ALTERNATOR
FIGURE 9-27n. BRUSH INSTALLATION
9-61j Precautions. The following precautions are
s stem
FIGURE 9-270. INTERNAL WIRING
DIAGRAM
to be observed when testing or serxicing the electrical
a Disconnect the battery before connecting or disconnecting test instruments (except xoltmeter) or
before remo\ing or replacing any unit or wiring Accidental grounding or shorting at the regulator. a liernato
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 energi/ed
c Do not attempt to polarize the alternator. No polarization is required An! attempt to do so ma!
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 ma! damage the rectifiers. wiring or other components of the
charging system Batter\ polarity should be checked with a voltmeter before connecting the batter! Molt
aircraft are negative ground
f If a booster battery or fast charger is used. its polarity must be connected correctl\ to prevent
damage to the electrical system components
9-61k Alternator Nomenclature.
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 ringend
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 is dis-
assembled The bearing should be thoroughly cleaned and repacked with Shell Alania No. 2 or an equivalent
bearing lubricant The cavity behind the bearing should be packed one-third to one-half full vith 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
ELECTRICAL SYSTEO ISSUED: 8/18/72
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