Piper PA-32R-301T SARATOGA S, Maintenance Manual

Page: 215 / 956

D.C. GENERATION (cont.)
(3) 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 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 2 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: Torque the drive pulley retaining nut to 35 foot-pounds.
(4) Checking Alternator System
With all electrical equipment off (except master switch) the ammeter will indicate the amount of
charging current demanded by the battery. This amount will vary, depending on the percentage of
charge in the battery at the time. As the battery becomes charged, the amount of current displayed
on the ammeter will reduce to approximately two amperes. The amount of current shown on the
ammeter will tell immediately whether or not the alternator system is operating normally, if the
following principles are kept in mind.
— NOTE —
The amount of current shown on ammeter is load in amperes
that is demanded by the electrical system from the alternator.
As a check, for example assume a condition where the battery
is demanding 10 amperes charging current, then switch on the
landing light. Note the value in amperes placarded on the cir-
cuit breaker panel for the landing light circuit breaker (10
amps) and multiply this by 80 percent, you will arrive at a cur-
rent of 8 amperes. This is the approximate current drawn by
the light. Therefore, when the light is switched on, there will be
an increase of current from 10 to 18 amperes displayed on the
ammeter. As each unit of electrical equipment is switched on,
the current will add up and the total, including battery, will
appear on ammeter.
PIPER AIRCRAFT
PA-32R-301/301T
MAINTENANCE MANUAL
24-30-00
Page 24-10
Reissued: July 1, 1993
1K10