panel is depressed, the coil winding in the magnetic switch is energized and the switch plunger is forced against the
contact switch to close the electrical circuit. Four 6-volt batteries are connected in series to provide 24 volts for ignition
and starting. The battery cable from ground is connected to the negative post of the last battery in the series.
d. Generating Circuit. The generating circuit supplies all of the electricity required by the electrical system. Basically,
this circuit consists of the generator, current and voltage regulator, ammeter, batteries, and all interconnecting cables and
wiring. The generator is driven by a belt between the generator and crankshaft pulleys. This is a two-brush generator with
ball bearings in the drive end and commutator end. A ventilating fan is mounted on the drive end of the armature shaft.
The current and voltage regulator is mounted on a bracket bolted to the top of the generator frame. This is a three-unit
regulator, consisting of a voltage regulator, current regulator, and cutout relay. The voltage regulator limits the voltage of
the electrical system, protecting the batteries, distributor points and other accessories from excessively high voltage. The
current regulator prevents the generator from exceeding its maximum output. The cutout relay closes the circuit between
generator and batteries when the generator is operating at a sufficient speed to charge the batteries. When the generator
slows down or stops, the cutout relay opens the battery-to-generator circuit to prevent the batteries from discharging back
to the generator. The ammeter indicates battery charge or discharge rate. When the engine-compressor is running at
normal speed, the ammeter hand should be in the "charge" range. If the ammeter shows a continuous discharge, the
condition of the generator, voltage regulator and batteries should be checked to determine the cause.
90. Batteries
a. Cleaning. Keep the batteries clean at all times. If electrolyte is spilled on the battery, wipe off with a weak solution
of baking soda and water. Then rinse off with clear water and dry with a clean cloth. Discard the wiping cloths. Clean the
battery terminals with a wire brush and wash them with a weak solution of baking soda and water. Rinse and dry terminals
after using cleaning solution and apply a thin coating of vaseline to restrict further corrosion.
b. Filling Battery Cells. Check the level of electrolyte in the batteries. The level should be at least '/8 inch, but not
more than -/g inch, above top of separators of each cell. Add only distilled water or water of known purity to the electrolyte.
81
