FLYWHEEL
ALTERNATOR
DES C
R
I
PT
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The battery charging flywheel alternator (Figures’e?
and 63) has a permanent magnet on the flywheel that
provides a rotating magnetic field.
A
group of coils
(stator) is mounted behind the flywheel on the gear
cover to “cut” the magnetic field, thus producing an
AC voltage. A solid-state voltage regulator controls
this AC voltage and a full wave rectifier converts the
regulated AC voltage to DC. This DC voltage is used
for keeping the battery charged and supplying power
to the electrical system.
The battery charging system has four major com-
ponents: (1) a permanent magnet on the flywheel
provides a rotating magnetic field; (2) agroup of coils
mounted behind the flywheel on the gear cover cut
the field to produce a voltage; (3) a2-step mechanical
regulator controls the AC voltage to the rectifier, and
(4) a full wave rectifier converts the regulated AC to
DC for battery charging.
The permanent magnet (rotor) is fastened to the
flywheel by screws. It is fully supported by the
flywheel and therefore has no bearings. The stator
windings are encapsulated in an epoxy resin for
protection from moisture. Cooling of the stator is
from special fins on the rotor. The rectifier is located
inside the blower housing and cooled by incoming
engine air.
A
fuse between the rectifier and ground
protects the rectifiers from destruction should the
battery be connected in the circuit with reversed
polarity. The mechanical regulator cannot tolerate
normal vibration of the engine,
so
it must be mounted
on a separate panel.
The battery charge voltage furnished by the flywheel
alternator (beginning with Spec T)
is
regulated by
solid state rectifiers with the combination regulator-
rectifier mounted on the blower housing. The
regulator automatically controls the battery charge
rate. There is no adjustment in the regulator.
Maintenance consists of keeping the heat-sink fins
clean at all times to permit adequate cooling. The
following is a list of do’s and don’ts.
1.
Do
Be Sure
Output Control Plug (connector) is
properly inserted in the stator receptacle. This
means the plug must push into and solidly bottom
in the receptacle
so
as to eliminate any resistance
due to a poor connection. Keep it clean and tight.
2.
Do
Be Sure
the Output Control (regulator) has a
good clean ground connection to operate proper-
ly. This means the mating surface where the
control unit mounts on the housing must beclean
and fastening bolts tiahtened properly.
3. Battery
-
Don’t
reverse battery leads. Reverse
The voltage regulator prior to Spec T provides two
different rates of current output. The smaller output
connects to the charge circuit for a continuous
low
charge rate. The larger output is controlled by the
mechanical regulator, with two relays, one
of
which is
voltage sensitive. When battery voltage falls and the
voltage sensitive relay is de-energized, contacts close
to provide
a
circuit to the other relay, which makes a
circuit for the high rate charge. See wiring
schematics, Figure 64.. The voltage at which the
sensitive relay is energized varies with the
temperature.
The final result is a charge rate of 12 amperes into a;
70-amp hour, 12-volt battery when the engine is
running at 1,800-rpm. The maximum continuous DC
load is limited to 10 amperes at 1,800-rpm. Reverse
current through the rectifiers is5- to 10-milliamperes,
so
no special reverse current protection is needed.
polarity will destroy the output control.
The engine should not be run while the battery
is
disconnected, but
if
the battery is accidentally disconnected, the system will not be
damaged.
MAINTENANCE
There are neither brushes nor bearings in thissystem
so
maintenance is limited to keeping thecomponents
in good condition. When the flywheel is off, clean the
rotor and stator and check the wires. In general, see
that all connections are secure and all components
clean.
If
the alternator is operating satisfactorily, do
not temper with it.
GENERAL
Several simple tests can help service personnel to
isolate the defective component in the charging
system.
1.
2.
Check voltages at battery, regulator and alter-
nator terminals.
a. Measure these readings while system is
operating satisfactorily.
b. This data will make
it
easy to spot a trouble
source when
it
occurs.
c. Record separate readings taken from each
engine, as they vary from system to system.
Check all accessories with an ammeter to make
sure they are drawing rated amperes and are not
I
oad
i
n g system excessively,
Redistribution or publication of this document,
by any means, is strictly prohibited.
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