MG MGB User Manual

THE
ELECTRICAL SYSTEM
N
24
A46|6AVI
Fig. N.l
The
C40/1
type
dynamo
l.
Commutator
end
bracket.
9.
Shaft
collar
retaining
cup.
17.
Through-bolts.
2.
Felt ring.
10.
Felt ring.
18.
Pole-shoesecuring
screws.
3.
Felt ring
retainer.
11.
Shaft key.
19.
Armature.
4,
Bronze
bush,
l2.
Shaft
nut.
20. Bearing
retaining plate.
5.
Thrust
washer.
13.
Output
terminal
‘D’. 21.
Ball bearing.
6.
Field coils.
14.
Brushes.
22. Corrugated
washer.
7.
Yoke.
15.
Field
terminal
‘F’.
23. Driving end
bracket.
8.
Shaft collar.
16. Commutator.
24. Pulley
spacer.
Dismantling
Test
the
brush
spring
tension, using
a
spring
scale. Th
Remove
the
securing
nut
and take
off the drive
pulley.
Remove
the
Woodruff key
from
the
commutator
shaft.
Unscrew
and
remove
the
two
through-bolts
and
take
off
the
commutator
end
bracket.
The driving
end
bracket,
together
with
the
armature
and
its
ball bearing,
can
now
be
lifted
out
of
the
yoke.
Unless
the
ball
bearing is
damaged
or
requires
attention
it
need
not
be
removed
from
the
armature.
Should
it
be
necessary
to
remove
the bearing,
the
armature
must-
be
separated
from
the end
bracket by
means
of
a
hand
press.
Servicing
BRUSHES
Lift
the
brushes
up
in
the
brush boxes
and
secure
them
in
that position
by positioning
each brush
spring
at
the
side
of
the
brush. Fit
the
commutator
end
bracket
over
the
commutator
and
release
the
brushes.
Hold
back
each
of the
brush
springs
and
move
the
brush by
pulling
gently
on
its
■exible
connector.
If
the
movement
is
sluggish,
reniove
the
brush
from
its
holder
and
ease
the sides
by
lightly
polishing
it
on
a
smooth
file. Always
re■t the
brushes
in
their
original
positions.
If the
brushes
are
badly
worn,
new
brushes
must
be
fitted
and
bedded
to
the
commutator.
The
minimum
permissible
length
of
brush
is
392
in.
(7.14
mm.).
MGB.
Issue3.
65891
tension
of
the
springs
when
new
is
18
to
24
oz.
(510.7
tr
681
gm.).
In service it is
permissible
for this value
to
fall
tc
15
oz.
(425 gm.) before
performance
may
be
affected. Fit
new
springs
if the
tension
is
low.
COMMUTATOR
A
commutator
in
good
condition will be
smooth
and free
from
pits
or
burned
spots.
Clean
the
commutator
with
a
cloth moistened
with fuel.
If this
is
ineffective
carefully
polish
with
a
strip
of fine glass-paper
while
rotating
the
armature.
To
remedy
a
badly
worn
commutator mount
the
armature
(with
or
without the drive
end
bracket)
in
a
lathe,
rotate
at
high speed,
and take
a
light
cut
with
a
very
sharp
tool. Do
not
remove more
metal than
is
necessary.
Polish
the
commutator
with
very
fine
glass-paper.
Undercut the
mica
insulation between
the
segments to
a
depth
of
3%
in.
(.8 mm.)
with
a
hacksaw
blade
ground down
to
the
thickness
of
the
mica.
Some
commutators
are
of the
moulded
type
and
may
be
skimmed
to
a
minimum
diameter
of 1.45
in.
(36.8 mm.).
The undercut
must
conform
to
the following dimensions:
Width
.
.040
in.
(1.02 mm.).
Depth
.020
in.
(.51
mm.).
It is important
that
the sides
of the undercut
clear the
moulding
material by
a
minimum
of
.015
in.
(.38
mm.).
.N.5

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English