Komatsu 830E-AC Shop Manual page 238

BATTERY CHARGING ALTERNATOR
GENERAL INFORMATION
General Description
The Niehoff model C653A 28-Volt (260 Amp) alterna-
tor is self-rectifying. All windings and current-trans-
mitting components are non-moving, so there are no
brushes or slip rings to wear out.
When controlled by voltage regulator (5), these alter-
nators become self-energizing through an internal
dual diode trio. A residual magnetic field induces a
small voltage in the stator and energizes the field
coil. The field coil continues receiving incremental
voltage until full voltage is achieved. Alternating cur-
rent (AC) is rectified into a direct current (DC) output
through the diodes. The regulator controls voltage
output and has a D+ terminal to provide a DC output
signal to the truck's electrical system, confirming
alternator operation. An R terminal provides optional
AC output.
1. Drive Shaft with Woodruff Key
2. Control Housing
3. Identification Plate
4. Battery Positive Terminal (B+)
5. Voltage Regulator
D10-8
This is a basic dual stator alternator constructed from
shell assembly (8) containing one stator at each end
and a field coil between the stators.
Drive end housing (9) and anti-drive end housing (6)
each contain a bearing to support drive and rotor
shaft (1). They are attached to each end of the shell
assembly by long threaded studs.
Drive end housing assembly (9) has an area called
control housing (2), containing all the required inter-
nal electrical connections for the alternator. It also
contains a thermal switch used to protect the B+ ter-
minal.
Battery positive terminal (4) is located on the face of
control housing (2) for connection to the truck's bat-
tery positive circuit. The ground circuit cable can be
attached to either of two ground terminals (10)
located on the front housing. Fan guard (7) protects
maintenance personnel from the rotating fan when
the engine is operating.
Identification plate (3) contains general alternator infor-
mation, including model number and serial number.
.
FIGURE 10-1. ALTERNATOR EXTERIOR
6. Anti-Drive End Housing
7. Fan Guard and Cooling Fan Assembly
8. Shell Assembly
9. Drive End Housing
10. Ground Terminals (B-)
Battery Charging Alternator D10003 07/06