BEARING AS-NEEDLE 8T1698 - Caterpillar

The electrical system is a negative ground system. The charging circuit operates when the engine is running. The alternator in the charging circuit produces direct current for the electrical system.Starting Motor
Illustration 1 g00954820
12 Volt Starting Motor
(1) Terminal for connection of the battery cable
(2) Terminal for connection of the ignition switch
Illustration 2 g00956095
24 Volt Starting Motor
(1) Terminal for connection of the ignition switch
(2) Terminal for connection of the battery cable The starting motor turns the engine flywheel. The rpm is 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 engage the pinion in the flywheel ring gear of the engine. When the pinion gear is engaged in the flywheel ring gear, the electrical contacts in the solenoid close the circuit between the battery and the starting motor. 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
Illustration 3 g00303424
(1) Shaft for mounting the pulley The alternator produces the following electrical output:
Three-phase
Full-wave
RectifiedThe alternator is an electro-mechanical component. The alternator is driven by a drive belt from the crankshaft pulley. The alternator charges the storage battery during the engine operation.The alternator converts the mechanical energy and the magnetic energy into electrical energy. 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 AC electrical power.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 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.