Royal Enfield CONSTELLATION 1958, Workshop Maintenance Manual

Page: 70 / 106

SECTION G2h
Generator/Rectifier Charging Set
1. General
(a) Constructional Notes
The alternator consists of a spigot mounted
6-coil laminated iron stator with a rotor carried
on and driven by an extension of the crankshaft.
The rotor has a hexagonal steel core, each face
of which carries a high energy permanent
magnet keyed to a laminated pole tip. The pole
tips are riveted circumferentially to brass side
plates, the assembly being cast in aluminium and
machined to give a smooth external finish.
As shown in Figure 1, there are no rotating
windings, commutator, brushgear, bearings or
oil seals and consequently the alternator requires
no maintenance apart from an occasional check
of the three-way connector in the three output
cables to see that this is clean and tight.
If removal of the rotor becomes necessary
for any purpose, there will be no necessity to fit
keepers to the rotor poles. When the rotor is
removed, wipe off any metal swarf that may
have been attracted to the pole tips and put the
rotor in a clean place.
STATOR AND ROTOR OF ALTERNATOR RM15
Fig. 1
(b) Rectifier
A bridge-connected rectifier is fitted to
convert the alternator output to a uni-directional
battery charging current. The rectifier requires
no maintenance apart from an occasional check
to see that the connections are clean and tight.
The nuts that clamp the rectifier plates together
must never under any circumstances be
slackened, as the clamping pressure has been
carefully adjusted during manufacture to obtain
the correct performance characteristics. A
separate nut is used for securing the unit to the
machine and this nut should be checked
occasionally to see that it is tight.
RECTIFIER
Fig. 2
(c) Operation
The alternator stator is wound with three
pairs of series-connected coils, one pair being
permanently connected across the rectifier. The
purpose of this latter pair is to provide a small
trickle charging current for the battery whenever
the engine is running.
Connections to the remaining coils vary
according to the demand on the battery and, as
shown schematically in Figure 3, depend on the
positions of the lighting switch. When no lights
are in use, the coils are short-circuited and the
alternator output is regulated to its minimum
value by interaction of the rotor flux with the
flux set up by the current flowing in the shorted
coils. In the "Pilot" or parking lights position,
the shorting link is disconnected and, the
regulating fluxes being consequently reduced,
the alternator output increases and compensates
Section G2h Page 1
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