Commutator Test
- Ensure continuity exists between any 2 commutator segments. If continuity does not exist, replace armature.
- Clean commutator segment surfaces with emery cloth and polish with No. 400 grit sandpaper (if necessary). If surface is scored, out-of-round, or pitted, turn commutator/armature assembly on a lathe.
- Using "V" blocks and dial indicator, ensure maximum commutator runout and minimum commutator diameter does not exceed specification after lathe turning. See COMMUTATOR SPECIFICATIONS .
- Standard undercut depth for insulating mica should be .016-.031" (.40-.80 mm). Minimum mica undercut depth is .008" (.20 mm). If depth is not within specification, undercut using hacksaw to specified depth.
COMMUTATOR SPECIFICATIONS
| Application | Max. Runout: In. (mm) | Min. Diameter: In. (mm) |
|---|---|---|
| Metro (M/T) | .016 (.40) | 1.06 (27.0) |