Alternator
Type:
Pre-1982 models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lucas 11AC or 16ACR
1982 to 1985 models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lucas A115
1986 models onward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lucas A127/45 or A127/55
Maximum output:
11AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 amps
16ACR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 amps
A115 and A127/45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 amps
A127/55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 amps
Minimum brush length:
11AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 mm
16ACR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 mm
A115 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 mm
A127/45 and A127/55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 mm
Starter motor
Type:
Pre-1986 models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lucas M35G or M35J (inertia type)
1986 models onward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lucas M79 (pre-engaged type)
Minimum brush length:
M35G and M35J . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.0 mm
M79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 mm
Brush spring tension:
M35G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425 to 710 g
M35J . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 794 g
M79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N/A
1 General information and
precautions
General information
The engine electrical system consists
mainly of the charging and starting systems.
Because of their engine-related functions,
these components are covered separately
from the body electrical devices such as the
lights, instruments, etc (which are covered in
Chapter 12). Information on the ignition
system is covered in Part B of this Chapter.
The electrical system is of the 12-volt
negative earth type.
The battery is of the low maintenance or
“maintenance-free” (sealed for life) type and is
charged by the dynamo or alternator, which is
driven by the fan belt.
The charging system on early models
consists of a dynamo and control box
incorporating a voltage regulator and cut-out.
The voltage regulator controls the output from
the dynamo depending on the state of the
battery and the demands of the electrical
equipment, and ensures that the battery is not
over-charged. The cut-out is really an
automatic switch and connects the dynamo to
the battery when the dynamo is turning fast
enough to produce a charge. Similarly it
disconnects the battery from the dynamo
when the engine is idling or stationary so that
the battery does not discharge through the
dynamo.
Later models are equipped with an
alternator in place of the dynamo and control
box. The Lucas 11AC alternator and separate
4TR control unit was used initially, but has
been superseded by the 16ACR, A115 and
A127 alternators with integral control units.
The alternators are all similar in
construction, comprising basically an
aluminium casing, housing a three-phase star
connected stator. A rotor carrying the field
windings rotates within the stator and is
driven by the fan belt. The alternator output is
controlled by a voltage regulator located in
the separate control unit on the 11AC
alternator and contained within the end
housing on the other machines.
As its name implies, the alternator
generates alternating current (ac) as opposed
to direct current (dc) generated by the
dynamo. The alternating current is rectified by
diodes, located in the alternator end housing,
into direct current, which is the current
required for battery charging.
On early models an inertia type starter
motor is fitted energised by a separate
solenoid switch mounted on the front inner
wing panel. When the ignition switch is turned,
current flows from the battery to the starter
motor solenoid, which causes it to become
energised. Its internal plunger moves inwards
and closes an internal switch, so allowing full
starting current to flow from the battery to the
starter motor. This causes a powerful
magnetic field to be induced into the field coils
which causes the armature to rotate.
Mounted on helical splines is the drive
pinion which, because of the sudden rotation
of the armature, is thrown forwards along the
armature shaft and so into engagement with
the ring gear. The engine crankshaft will then
be rotated until the engine starts to operate on
its own and, at this point, the drive pinion is
thrown out of mesh with the ring gear.
A pre-engaged type starter motor is fitted
to all models from 1986 onward. On starting,
the integral solenoid moves the drive pinion
into engagement with the flywheel ring gear
before the starter motor is energised. Once
the engine has started, a one-way clutch
prevents the motor armature being driven by
the engine until the pinion disengages from
the flywheel.
Precautions
Further details of the various systems are
given in the relevant Sections of this Chapter.
While some repair procedures are given, the
usual course of action is to renew the
component concerned. The owner whose
interest extends beyond mere component
renewal should obtain a copy of the
“Automobile Electrical & Electronic Systems
Manual”, available from the publishers of this
manual.
It is necessary to take extra care when
working on the electrical system to avoid
damage to semi-conductor devices (diodes
and transistors), and to avoid the risk of
personal injury. In addition to the precautions
given in “Safety first!” at the beginning of this
manual, observe the following when working
on the system:
Always remove rings, watches, etc before
working on the electrical system. Even with
the battery disconnected, capacitive
discharge could occur if a component’s live
terminal is earthed through a metal object.
This could cause a shock or nasty burn.
Do not reverse the battery connections.
Components such as the alternator, electronic
control units, or any other components having
semi-conductor circuitry could be irreparably
damaged.
5A•2 Starting and charging systems
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