------
---
----
Commutator
A
commutator
in good condition will be
smooth
and
free from piU and
burned
spots. Clean
the
com-
mutator
with a petrol-moistened
doth.
If this is
ineffective. carefully polish with a
strip
of fine glass-
paper, while
rotating
the
armature.
To
remedy
a
badly
worn
commutator.
dismantle
the
starter
drive
aspreviously descrIbed and remove
the
armature
from
the
end
bracket.
Now
mount
the
armature
in a
lathe.
rotate
it at a high speed and
take
a light
cut
with
HAN
D PRESS
®
BUSH
SUPPORTING
BLOCK
----~-
©
Fig. N.15.
The method of Illsening ;J ne
.....
bush in the
starter
end
cover. Note
use of supportlng btceks.
a very sharp
tool.
Do
not
remove any
more
metal
than
is absolutely necessary. and finally polish with very
fine glass-paper.
The
insulator between
the
commutator
segments
must
not
be
undercut.
Field
coils
The field coils can be
tested
for an open circuit by
connecting a 12-volt
battery.
with a 12-volt bulb In
one
of
the
leads,
to
the
tapping
point
of
the
field coils
to
which
the
brushes
are
connected, and
the
field
terminal
post. If
the
lamp does
not
light.
there
Is an
open circuit in
the
wiring of
the
field coils.
Lighting of
the
lamp does
not
necessarily mean
that
the
field coils
are
in
order,
as It Is possible
that
one
ELECDlICAL
EqUIPMElYr
N
of
them
may be
earthed
to
a pole
shoe
or
to
the
yoke. This may be checked by removing
the
lead
from
the
brush
connector
and holding it on a clean
part
of
the
starter
yoke. Should
the
bulb now
light it indicates
that
the
field calls are
earthed.
Should
the
above
tests
indicate
that
the
fault lies In
the
field coils.
they
must
be
renewed.
When
renewing
field coils carry
out
the
procedure
detailed In
the
Dynamo Section N.S.
Armature
Examination of
the
armature
will In many cases
reveal
the
cause ef fallure, e.g. conductors lifted from
the
commutator
due
to
the
starter
being engaged
while
the
engine is running and causing
the
armature
to
be
rotated
at an excessive speed. A damaged
armature
must in all cases be
renewed-no
attempt
should be made
to
machine
the
armature
core
or
to
true
a
distorted
armature
shaft.
Bearings
Bearings which
are
worn
to
such
an
extent
that
they
will allow excessive side play of
the
armature
shaft
must be
renewed.
To
renew
the
bearing bush,
proceed as follows
:-
(0) Remove
the
old bearing bush by pressing it
out
of
the
end bearing, using a suitable
shouldered
mandrel In
the
press. Take care
that
the
mandrel does
not
contact
the
bearing face and
damage it during removal.
(b) Press
the
new bearing bush
into
the
end
bracket, using
a
shouldered
mandrel of
the
same
diameter
as
the
shaft which is
to
fit in
the
bearing.
Note.-The
bearing
bushes
are of the
porous
phosphor-bronze
type. and
before
fitting them they
should
be
allowed
to stand completely
Immersed
for twenty-four hours in thin engine
01/
to Ref. F
(poge P.2) in order to
fill
the
pores
af the bush
with lubricant.
Reassembly
The
reassembly of
the
starter
is a reversal of
the
operations
descrIbed above.
Note.-Secure
the body of the starter in a vice and
test by connecting It with heavy-gauge cables
to a battery
of the correct voltage. One cable must be connected to
the starter
termlncrl
andthe other heldagainst the starter
body.
or end bracket.
Under
these light load
conditions
the
starter
should
run at a very high speed.
N.1l
Wishvilles Classic
Automobile Library
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