Cummins/Onan — Lathe-Turning Collector Rings or Commutator
Repair & overhaul · Armature/collector rings/commutator
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MCCK
Before you start
- The lathe refinishing process can damage the ball bearing; shield the ball bearing during refinishing.
- Cut a slight chamfer to reduce the possibility of flash over between the rings.
Procedure
- Remove the armature and center it on a lathe.
- Turn the commutator or collector ring just enough to provide a true concentric surface.
- Use #240 sandpaper to remove tool marks.
- After turning the slip rings, cut a slight chamfer to remove burrs and sharp edges.
- After turning the commutator, undercut the mica insulation between the commutator bars.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan MCCK →
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.