Cummins/Onan — Turning Down Commutator or Collector Rings
Repair & overhaul · Generator armature
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
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Before you start
- Grinding the commutator is needed if grooved, out of round, pitted or rough.
Procedure
- Remove the generator field frame.
- Remove the ball bearing from the armature shaft before turning down.
- Turn the commutator or collector rings down in a lathe.
- Undercut the mica between bars after turning down.
- Align the armature carefully before installing frame and end bell.
Tools required
- Lathe Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: Cummins/Onan owner's 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.