Starting Motor
Illustration 18
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Typical example
12 Volt Starting Motor
(1) Terminal for connection of the ground cable
(2) Terminal 30 for connection of the battery cable
(3) Terminal 50 for connection of the ignition switch
Illustration 19
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Typical example
24 Volt Starting Motor
(1) Terminal for connection of the ground
(2) Terminal 30 for connection of the battery cable
(3) Terminal 50 for connection of ignition switch
The starting motor turns the engine via a gear on the
engine flywheel. The starting motor speed must be
high enough in order to initiate a sustained operation
of the fuel ignition in the cylinders.
The starting motor has a solenoid. When the ignition
switch is activated, voltage from the electrical system
will cause the solenoid to move the pinion toward the
flywheel ring gear of the engine. The electrical
contacts in the solenoid close the circuit between the
battery and the starting motor just before the pinion
engages the ring gear. This causes the starting motor
to rotate. This type of activation is called a positive
shift.
When the engine begins to run, the overrunning
clutch of the pinion drive prevents damage to the
armature. Damage to the armature is caused by
excessive speeds. The clutch prevents damage by
stopping the mechanical connection. However, the
pinion will stay meshed with the ring gear until the
ignition switch is released. A spring in the overrunning
clutch returns the clutch to the rest position.
Alternator
The electrical outputs of the alternator have the
following characteristics:
• Three-phase
• Full-wave
• Rectified
The alternator is an electro-mechanical component.
The alternator is driven by a belt from the crankshaft
pulley. The alternator charges the storage battery
during the engine operation.
The alternator is cooled by an external fan which is
mounted behind the pulley. The fan may be mounted
internally. The fan forces air through the holes in the
front of the alternator. The air exits through the holes
in the back of the alternator.
The alternator converts the mechanical energy and
the magnetic field into alternating current and voltage.
This conversion is done by rotating a direct current
electromagnetic field on the inside of a three-phase
stator. The electromagnetic field is generated by
electrical current flowing through a rotor. The stator
generates alternating current and voltage.
The alternating current is changed to direct current by
a three-phase, full-wave rectifier. Direct current flows
to the output terminal of the alternator. The direct
current is used for the charging process.
A regulator is installed on the rear end of the
alternator. Two brushes conduct current through two
slip rings. The current then flows to the rotor field. A
capacitor protects the rectifier from high voltages.
The alternator is connected to the battery through the
ignition switch. Therefore, alternator excitation occurs
when the switch is in the ON position.
UENR0617
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This document has been printed from SPI2. NOT FOR RESALE.