Alternator And Components (Prestolite); Description Of Alternator - Piper Navajo Chieftain PA-31-350 Service Manual

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Figure 11-3. Exploded View of Alternator (Prestolite)
11-7. ALTERNATOR AND COMPONENTS (Prestolite).
11-8. DESCRIPTION OF ALTERNATOR. (Refer to Figure 11-3.) The principal components of the
alternator are the brush holder assembly (1), the slip ring end head (2), the rectifiers (3), the stator (4), the
rotor (5) and the drive end head (6).
a. The brush and holder assembly contains two brushes, two brush springs, a brush holder and
insulators. Each brush is connected to a separate terminal stud and is insulated from ground. The brush
holder assembly can easily be removed for inspection or brush replacement purposes.
b. The slip ring end head provides the mounting for the rectifiers and rectifier mounting plate,
output and auxiliary terminal studs, and the brush and holder assembly. The slip ring end head contains a
roller bearing and outer race assembly and a grease seal.
c. The rectifiers used in these units are rated at 150 peak inverse voltage (PIV) minimum for
transient voltage protection. Three positive rectifiers are mounted in the rectifier mounting plate while the
three negative rectifiers are mounted in the slip ring end head. Each pair of rectifiers is connected to a
stator lead with high temperature solder. The stator leads are anchored to the rectifier mounting plate with
epoxy cement for vibration protection.
d. The stator contains a special lead which is connected to the center of the three phase windings
and is used to activate low voltage warning systems or relays. The stator has been treated with a special
epoxy varnish for high temperature resistance.
e. The rotor contains the slip ring end bearing inner race and spacer on the 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 the
winding leads to the slip rings.
f. The drive end head supports a sealed, prelubricated ball bearing in which the drive end of the
rotor shaft rotates.
Revised: 10/15/82
ELECTRICAL SYSTEM
NAVAJO CHIEFTAIN SERVICE MANUAL
3C19