Royal Enfield METEOR MINOR STANDARD 1958 Workshop Maintenance Manual page 36

Lucas A.C. Lighting-Ignition System
1. General
The Lucas A.C. Lighting-Ignition System
comprises seven main components
(1) Alternator with magnet rotor.
(2) Bridge-connected rectifier.
(3) Ignition coil.
(4) Distributor with automatic timing control.
(5) Lighting switch.
(6) Ignition switch.
(7) 6-volt battery (see Section G4a).
Under normal running conditions, electrical
energy in the form of rectified A.C. passes
through the battery from the alternator, the rate
of charge depending on the position of the
lighting switch. When no lights are in use, the
alternator output is sufficient only to trickle
charge the battery. When the lighting switch is
turned to the "Pilot" or "Head" positions the
current increases proportionately.
STATOR AND ROTOR OF ALTERNATOR RM15
2. Alternator Models RM14 and RM15
Early models are fitted with type RM14
alternator, which has an outside diameter of 5.7/8
in. Later models are fitted with type RM15 (see
Fig. 1) with an outside diameter of 5 in. They
give a high output at low r.p.m. The alternator
comprises two main components, a stator and a
rotor. The stator is built up from iron laminations
and carries three pairs of series-connected coils
insulated from the laminations. The rotor has a
hexagonal steel core, each face of which carries a
SECTION G2j
Meteor Minor
Fig. 1
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. The stator and rotor can be
separated without the need to fit magnetic
keepers to the rotor poles.
As the rotor turns, rapid and repeated
reversals of flux take place in the coil cores.
These lines cut through the turns of the coil and
induce alternating voltages in that coil. External
connections are taken to these coils from a
bridge connected rectifier (see Fig. 2).
3. Circuit Detail
The alternator stator carries three pairs of
series connected
permanently connected across the rectifier bridge
network. The purpose of this latter pair is to
provide some degree of charging current for the
battery whenever the engine is running.
GENERAL VIEW OF RECTIFIER
Connections to the remaining coils vary
according to the position of the lighting and
ignition switch controls, as shown schematically
in Fig. 3.
When no lights are in use the alternator
output is regulated to its minimum value by
interaction of the rotor flux and the flux set up
by current flowing in the short-circuited coils.
coils, one pair
Fig. 2
Section G2j Page 1
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