BOLT 9X2546 - Caterpillar

The electrical system has three separate circuits. The circuits are the charging circuit, the starting circuit, and the low amperage circuit. Some of the electrical system components are used in more than one circuit. The following components are common in each of the circuits:
battery
circuit breaker
ammeter
cable
wires for the batteryThe charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output in order to keep the battery at full charge.The starting circuit is in operation only when the start switch is activated.The circuit that has a low amperage is connected to the same side of the ammeter as the charging circuit. The starting circuit connects to the opposite side of the ammeter.Charging System Components
Never operate the alternator without the battery in the circuit. Making or breaking an alternator connection with heavy load on the circuit can cause damage to the regulator.
Alternator
Illustration 1 g00285111
Alternator Components (Typical Example) (1) Regulator. (2) Roller bearing. (3) Stator winding. (4) Ball bearing. (5) Rectifier bridge. (6) Field winding. (7) Rotor assembly. (7) Fan.The alternator is driven by a belt from an auxiliary drive at the front right corner of the engine. This alternator is a three-phase, self-rectifying charging unit, and the regulator is part of the alternator. This alternator design has no need for slip rings or brushes, and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The conductors are the field winding, stator windings, six rectifying diodes, and the regulator circuit components.The rotor assembly has many magnetic poles with air space between each opposite pole.The poles have residual magnetism that produces a small amount of magnetic lines of force between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings. This current is from the small, magnetic lines of force that are made by the residual magnetism of the poles. This alternating current (AC) is changed to a direct current (DC). The change occurs when the current passes through the diodes of the rectifier bridge. Most of this current charges the battery and the current supplies the circuit that has a low amperage. The remainder of the current is sent to the field windings. The DC current flow through the field windings (wires around an iron core) now increases the strength of the magnetic lines of force. These stronger lines of force increase the amount of AC current that is produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator.The voltage regulator is a solid-state, electronic switch. The regulator feels the voltage in the system. The regulator turns on and the regulator turns off many times in one second in order to control the field current to the alternator. The output voltage from the alternator will now