Table 2. Commutator Problems (Continued)
Problem Possible Cause Illustration
1. Flashover causes
burning of the
ends of the com-
mutator bar.
2. Open circuit in
winding causes
deep burning of
adjacent commu-
tator bars.
3. Overheating cau-
ses damage to
varnish insulation.
• Motor has been
too hot. Wrong lift
truck for the appli-
cation.
• Motor has been
stalled.
• Open armature
winding.
• Open field coil.
Brush and commutator
damage occurs when the
high commutator hits and
forces the brush up. Arc-
ing and burns occur as
the brush moves back
down to the normal sur-
face. Check for loose or
high commutator bars.
• Motor has been
stalled. (High com-
mutator bars at
each brush posi-
tion can occur if
the motor is stal-
led.)
• Motor has been
too hot.
1.High commutator bars at each brush position can
occur if the motor is stalled.
2.Rapid brush wear from high commutator bars.
0620 YRM 0294 Brush and Commutator Inspection
9