ALTERNATOR SYSTEM (PRESTOLITE)
DESCRIPTION OF ALTERNATOR (figure 2~28)
Principal alternator components are brush holder assembly, slip ring end head, rectifiers, stator, rotor, and
drive end head.
1. The brush and holder assembly contains two brushes, two brush springs, brush holder, and insulator.
One brush is connected to a terminal stud and is insulated from ground. The other brush is connected
to ground through brush holder. The brush and holder assembly is removed for inspection or brush
replacement purposes.
2. The slip ring end head provides mounting for rectifiers and rectifier mounting plate, output and
auxiliary terminal studs, and brush and holder assembly. The slip ring end head contains a roller
bearing, outer race assembly, and a grease seal.
3. The rectifiers used in these units are rated at l50 peak inverse voltage (piv) minimum for transient
voltage protection. Three positive rectifiers are mounted in rectifier mounting plate while three
negative rectifiers are mounted in slip ring end head. Each pair of rectifiers is connected to a stator
lead with high temperature solder. The stator leads are anchored to rectifier mounting plate with epoxy
cement for vibration protection.
4. The stator contains a special lead which is connected to the center of the three phase windings. The
stator has been treated with a special epoxy varnish for high temperature resistance.
5. The rotor contains the slip ring end bearing inner race and spacer on slip ring end of the shaft. The
rotor winding and winding leads have been specially treated with a high temperature epoxy cement to
provide vibration and temperature resistance characteristics. High temperature solder is used to secure
winding leads to slip rings.
6. The drive end heads supports a sealed, pre-lubricated ball bearing in which drive end of rotor shaft
rotates.
DISASSEMBLY OF ALTERNATOR
l. Remove two l0-24 screws holding brush holder assembly in slip ring end head. Remove brush and
holder assembly from end head.
2. Remove safety wire from bolts. Hold pulley with a strap wrench and remove pulley nut. Pulley must
be removed with a puller. Remove fan, woodruff key and spacer from shaft.
3. Remove four bolts and tap drive end head lightly to separate drive end head and rotor, as a unit, from
stator and slip ring end head.
4. Remove nuts, lockwashers, flat washers, and insulators from output and auxiliary terminal studs. Note
correct assembly of insulator washers and bushings. Using special tools shown in figure 24-30, support
end head and press out three negative rectifiers. End head can now be separated from stator assembly.
5. To remove slip ring end bearing and grease seal, it is necessary to have a hook type or impact type
bearing puller as shown in figure 24-29. Do not remove bearing unless replacement is necessary.
—NOTE—
Inner race of slip ring end bearing is pressed onto rotor shaft.
When bearing replacement is necessary, always replace complete
bearing assembly, including inner race.
24 - 33 - 00
Page - 24 - 27
Reissued: August 1, 1986
1J2
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
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