Sunbeam ALPINE I SERIES: APLINE II SERIES, Workshop Manual

Page: 322 / 413

I
st re-issue
Page8
Fl1, 4.
Assembling end bracket and brushes
to generator
brushes are badly worn, new brushes must be
fitted and bedded to the commutator. The
minimum permissible length of brush Is
f'.
(6 mm.).
4. Test the brush spring tension using a spring
scale (See Fig. 5). The tension of the spring
when new is 15/25 oz. (·42/·71 kgs.) when
exerted on a new brush. Fit new springs if
the tension is low.
Fl1, S. Testinr
brush spring
tension
Commutator
WSM.124
Section N (Elec. Equip.)
A commutator in good condition will be smooth
and free from pits or burned spots.
teUP
CORRECT
INCORRECT
Fig, 6
Undercutting commutator insulation
Clean the commutator with a petrol-moistened
cloth. If this is Ineffective, carefully polish with a
strip of fine glass paper while rotating the armature.
The commutator is of moulded construction and
can be re-skimmed during service, but care must
be exercised to ensure that the finished diameter
Is not less than 1 ·450• (36·8 mm.). The process of
re-skimming consists of rough turning, undercutting
and diamond turning-In that order. Whether or
not rough turning Is carried out depends upon the
severity and unevenness of wear which has taken
place. If a commutator cannot be completely
cleaned up without going below the specified dia­
meter, the armature must be replaced.
The width of undercut slots must not exceed
0·04'0" (1 mm.) with a depth of 0·020"-0·035"
(0·5-
0·9
mm.).
A hacksaw blade ground to the thickness of the
Insulator can be used. (See Fig. 6).
If a non-diamond-tipped tool ls used for machining,
the commutator should afterwards be lightly
polished with a very fine glass-paper-never emery
cloth.