Cummins/Onan 3.6MKY / 4MKY — Slip Ring Service
Maintenance · Slip rings
For the Cummins/Onan 3.6MKY / 4MKY, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 3.6MKY, Cummins/Onan 4MKY
Before you start
- Careless handling of rotor can damage the insulation on the windings
Procedure
- Remove the fan (Steps 1 through 9).
- Inspect slip rings for grooves, pits, or other damage; use Scotch Brite pad for light wear.
- Remove endbell and rotor.
- Place rotor in machine lathe and center.
- Turn rotor and use commutator stone (Onan tool #420-0259) against rotating slip rings to clean and true.
- Turn rotor until all grooves or roughness are smoothed out.
- Clean and reinstall the rotor.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Run-out must be less than 0.0001 inch
- Surface finish must be less than 32 micro inch
- Recondition if out of round by more than 0.002 inches
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.