Alternator

TM 10-3930-633-12

e. Charging System. The charging system

improper connections. Battery and ground

consists of the alternator, regulator, battery, and

connections are made at the studs on the end

ammeter. The arrangement of these components

frame.

is shown in figure 4-5. The alternator is belt

4-26. Alternator Output Test

driven by the engine. Field current levels in the

To test the output of the alternator on the vehicle,

alternator are controlled by the voltage regulator,

proceed as follows:

and are varied as required to suit battery loads

a. Place the transmission in neutral and apply

and state of charge.

the parking brake. Make the connections as

4-25. Alternator

shown in figure 4-8.

a. The alternator is an alternating current

b. Start the engine.

generator, driven by means of V-belts from the

c. Increase the engine speed to approximately

engine crankshaft damper. The alternating

2000 RPM. Turn off all lights and electrical ac-

current is rectified internally by means of diodes,

cessories.

so that alternator output is in DC current. These

d. Turn the load rheostat clockwise until 15

diodes are contained in the end frame of the

volts is indicated on the voltmeter.

alternator.

e. Observe alternator output as registered on

b. The rotor is supported at each end by ball or

the ammeter. Output should be approximately 20

roller bearings, and the rotor is dynamically

amps at an ambient temperature of 800 F.

balanced. Both end frames are equipped with

f. An output of 2 to 8 amperes below

f a c t o r y - p a c k e d grease reservoirs, which

specifications usually indicates an open diode

eliminates the need for periodic lubrication.

rectifier. An output of approximately 10 to 15

c. Installation ease is aided by a single

amperes below specifications usually indicates a

mounting lug and a slip-type field connector. The

shorted diode rectifier. An alternator with a

connector is polarized so that it can be connected

shorted diode will usually whine, which will be

only one way thus eliminating the hazard of

most noticeable at idle speed.

Figure 4-8. Alternator Output Test Circuit

4-27. Alternator Removal and Replacement .

(1) Disconnect the battery ground cable.

(2) Loosen the alternator adjusting arm bolt,

a. Removal.

4-20