Treatment Of Badly Worn Commutator; Sticking Brushes; Worn Brushes; Test And Replacement Of Field Coil - Royal Enfield CO Workshop Maintenance Manual

ROYAL ENFIELD 350cc O.H.V. WORKSHOP MANUAL

75. Treatment of Badly Worn Commutator.

To remedy a badly worn commutator it will be
necessary first to remove the armature from the
dynamo. (See dismantling, Para. 72).
Mount the armature complete with the 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. Now undercut the mica insulation
between the commutator segments to a depth of 1/32
in. below the surface of the segments. A hacksaw
blade, ground down until it is only slightly thicker
than the mica forms a suitable tool. Draw this
backwards and forwards along the mica until it is
undercut to the proper depth. See Fig. 55.

76. Sticking Brushes.

Test by holding back the brush spring and moving
the brush in its holder. If the brush tends to stick,
remove it and clean with petrol.
Check spring tension as shown in Fig. 56. Correct
tension is 10-15 ozs.

UNDERCUTTING MICA

77. Worn Brushes.

Brushes which have worn to such an extent that
they do not bear properly on the commutator must be
replaced. Remove machine from engine and withdraw
dynamo cover band. Remove screw securing eyelet on
end of brush lead. Hold back brush spring and remove
brush from its holder. Place new brush in holder and
gently lower the spring. Secure eyelet on end of brush
lead in original position.

EXPLODED VIEW OF DYNAMO

Fig. 55
Fig. 54

TESTING BRUSH SPRINGS FOR TENSION

78. Test and Replacement of Field Coil.

The fitting of the field coil requires the use of a
pole expander. If one is not available, do not attempt
to replace the coil. When fitting a new field coil, take
care to tighten the pole shoe fixing screw to the fullest
extent.

COMMUTATOR AND BRUSH GEAR

Fig. 56
Fig. 57
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