16
FIGURE 21. COMMUTATOR PROBLEMS
Grooves that are the width of the brushes.
Possible Causes:
Operation of the motor in dirty and abrasive
conditions
Wrong type of brushes for this motor and operation.
Brush pressure is too high.
6939
FIGURE 22. COMMUTATOR PROBLEMS
A condition called “copper drag” occurs when copper
from the commutator bar is pulled into the slot between
the commutator bars. This condition will cause a
short–circuit between the commutator bars if it is not
corrected. The brushes will wear rapidly.
Possible Causes:
Operation of the motor in dirty and abrasive
conditions.
Brush holder is not adjusted electrically correct for the
motor.
Wrong type of brushes for this motor and operation.
Brush pressure is wrong (too high or too low).
6946
FIGURE 23. COMMUTATOR PROBLEMS
Electrical burns on commutator bars on opposite sides
of the commutator.
Possible Causes:
Open armature winding
Motor has been stalled.
6939