Model

Good Condition-Light FilmUniform coloring indicates satisfactory operation of the machine and brushes. Acceptable film color may vary from light to dark due to film thickness.

Satisfactory Condition-Light and Dark Pattern

This condition can appear in alternating bars as shown or every 3rd or 4th bar. This is caused by imbalances in the windings or other motor variances. It is not an indication of commutator problems. The motor should have no issues running, but the condition may indicate a need for more frequent inspections.

Unsatisfactory Condition-Streaky Film With No Commutator Wear

Threading or streaked film on the commutator surface. May be accompanied by rattling or loud operation. This condition is frequently due to incorrect brush grade. Environmental conditions, such as freezer or low humidity, can be a contributing factor. This condition may be repaired with a polishing stone if caught soon enough. Refer to ““Polishing the Commutator” on page7-61

Unsatisfactory Condition-Uneven Film

Patchy colors of varying densities and shape. This condition is generally due to unclean operating conditions and does not indicate damage to the commutator. Clean the commutator with a polishing stone and compressed air (see “Polishing the Commutator” on page7-61 ). Consider more frequent scheduled maintenance intervals.

Unsatisfactory ConditionFilm With Dark Areas

Dark areas can be isolated or regular. This condition indicates a commutator is out-of-round. Continued use may result in failure and damage to other systems. The motor should be replaced or re-cut at a qualified repair facility.

Unsatisfactory Condition-Example of Incorrect Commutator

Machining

Unsatisfactory Condition-Example of Incorrect Commutator

Machining

Bars are low on entry and leaving edges causing the brushes to ride on the middle of the bars. Continued use may result in failure and damage to other systems. The motor should be replaced or re-cut at a qualified repair facility. Consider more frequent scheduled maintenance intervals.

Bars are low in the middle causing the brushes to ride on the entry and leaving bar edges. Continued use may result in failure and damage to other systems. The motor should be replaced or re-cut at a qualified repair facility. Consider more frequent scheduled maintenance intervals.

Publication: 1146947, Revised: 12 Jan 2017