NOTE
The higher tension specified for a new belt is to compensate for the initial
stretch that takes place as soon as it is operated. These higher tension values
should not be applied to belts which have previously been used.
11-32. ALTERNATOR SYSTEM (PRESTOLITE).
WARNING
When servicing or inspecting vendor equipment installed in Piper aircraft, it
is the user’s responsibility to refer to the applicable vendor publication.
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 is disassembled.
The bearing should be thoroughly cleaned and repacked with Shell Alvania No. 2 or an equivalent
bearing lubricant. The cavity behind the bearing should be packed one-third to one-half full with 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 cavities. Use a pin or a
piece of wire, as shown in Figure 11-35, to hold the brushes in the holder during assembly. Remove
the pin after the brush holder retaining screws have been tightened. Make a continuity check to be sure
the brushes are seated against the slip rings.
d. Drive Pulley: On PA-28R-201, torque the drive pulley retaining nut to 35 foot-pounds.
11-34. ALTERNATOR SERVICE PRECAUTIONS. Since the alternator and regulator are designed for use on
only one polarity system, the following precautions must be observed when testing or servicing the electrical
system. Failure to observe these precautions will result in serious damage to the electrical equipment.
a. Disconnect the battery before connecting or disconnecting test instruments (except voltmeter) or
before removing or replacing any unit or wiring. Accidental grounding or shorting at the regulator,
alternator, 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. No 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.
g. When using an auxiliary power unit, make sure the voltage and polarity are set to correspond with the
aircraft system voltage and polarity.
Revised: 2/13/89
2H11
CHEROKEE ARROW III SERVICE MANUAL
ELECTRICAL SYSTEM
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