The charging circuit operates when the engine is running. The alternator in the charging circuit produces direct current for the electrical system.
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| Illustration 1 | g00295928 |
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Starting Motor (1) Terminal for connection of the battery cable (2) Terminal for connection of the ignition switch | |
The starting motor turns the engine flywheel. The rpm 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 barely 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.
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| Illustration 2 | g00303424 |
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Alternator (1) Shaft for mounting the pulley | |
The alternator produces the following electrical output:
- Three-phase
- Full-wave
- Rectified
The alternator has brushes. The alternator is an electro-mechanical component. The alternator is driven by a belt from the fan drive 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 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 energy 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 rectifier has three exciter diodes. The direct current is used for the charging process.
A solid state 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.
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| Illustration 3 | g00281837 |
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Circuit Breaker With Reset Button (1) Reset button (2) Metal disc in the open position (3) Contacts (4) Metal disc in the closed position (5) Battery circuit terminals | |
Most models have a circuit breaker. The circuit breaker is a switch that opens the circuit if the current in the electrical system is higher than the rating of the circuit breaker. The metal disc (2) is activated by heat. The metal disc has contact points which complete the electrical circuit through the circuit breaker. If the current in the electrical system gets too high, the metal disc will get hot. This heat causes a distortion of the metal disc. This distortion causes the contact points to open the circuit. A circuit breaker that is open can be reset when the metal disc becomes cooler. Push the reset button (1) in order to close the contact points and reset the circuit breaker.