Cummins/Onan — Commutator Maintenance
Maintenance
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Do not use emery or carborundum paper.
Procedure
- Do not maintain bright newly machined surface.
- Clean with dry lint free cloth.
- Use very fine sandpaper (#00) to remove slight roughness with light pressure while plant operating.
- Do not use emery or carborundum paper. Clean out carbon dust.
- If commutator worn down to mica, undercut mica between bars to 1/32 inch below surface.
- Use tool from hacksaw blade ground to mica thickness. Do not scratch bar surfaces.
- Remove burrs with sandpaper. Clean spaces between bars.
- If commutator grooved or out of round, turn smooth on lathe and undercut mica.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- mica undercut 1/32 inch below bars
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.