Specifications

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CHAPTER 6 ELECTRICAL SYSTEMS
GENERAL INFORMATION
The electrical system consists of three main elements: a battery, a starting circuit, and a charging circuit. The battery is
part of both the starting and charging circuit. The battery should be checked before going into any extensive starter or
charging system checks. If a battery has a shorted cell, overcharging can result, and the regulator or rectifier may appear
to be at fault. If a cell has an open or high resistance connection, the electric starter operation will be affected.
The power source used to provide the energy to turn an electric starter motor on Tecumseh engines is either 120 volt A.C.
current or 12 volt D.C. An A.C. starter circuit utilizes a 120 volt power source instead of a battery. The 12 volt battery
models require a charging system to maintain proper battery charge.
The starting circuit includes the battery, battery cables, starter or ignition switch, safety switches, and an electric starter
motor.
The charging system consists of alternator charge coils, rectifiers or diodes, regulator, ignition switch, flywheel magnets,
and a battery. All engines that have a charging system will use a combination of some or all of these features.
OPERATION
1
THRUST WASHER
END CAP
ARMATURE
SPRING
GEAR
ENGAGING NUT
NUTS
WASHER
END CAP
DUST COVER
RETAINER
SPRING
RETAINER
HOUSING
BRUSH CARD
BRUSH SPRINGS
BRUSHES
BOLT
LOCK NUT
ROTATION OF FLYWHEEL
2
STARTING CIRCUIT AND ELECTRIC
STARTERS
After all of the safety interlock switches have been activated,
the starter switch will complete the circuit. A strong
magnetic force is produced by the electrical current running
through the armature windings. The armature magnetism
repels the magnetism produced by the permanent field
magnets of the electric starter. The repelling magnetic
forces cause the armature to rotate, moving the drive pinion
laterally on the splined armature shaft, meshing the starter
pinion gear with the flywheel ring gear. When the drive pinion
contacts the stop at the end of the armature shaft, the
pinion rotates along with the armature shaft to crank the
engine. The armature and pinion remain positively engaged
until the engine fires and the flywheel rotates faster than
the armature. The greater momentum of the flywheel throws
the starter pinion gear out of mesh and forces the starter
pinion back to the disengaged position. After the switch is
released, the starting circuit is opened and the armature
coasts to a stop. A small anti-drift spring holds the pinion
in the disengaged position (diag. 1).
CHARGING CIRCUIT
When a conductor (alternating coils) cuts the magnetic
field generated by the magnets in the flywheel, a current
will be induced in the alternator coil. The permanent
magnets in the flywheel have a magnetic field in which the
lines of magnetic force run from the North Pole to the South
Pole. As the flywheel rotates and the position of the
magnets change, the direction of the magnetic field
changes or alternates. The alternating coils are wound in
different directions to allow current to flow as an A.C.
waveform (diag. 2).