Cummins/Onan — Brushes and Slip Rings - Checking and Replacing
Maintenance · Generator brush block and slip rings
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HDKC, Cummins/Onan HDKCA, Cummins/Onan HDKCB
Before you start
- Disconnect negative battery cable before service.
Procedure
- Remove brush block access cover.
- Check brush wear by inserting wire marked at 1 inch into each hole; replace brush if wire inserts more than 1 inch.
- If slip rings grooved or pitted, clean with commutator stone while cranking engine.
- When replacing brush block, center brushes on slip rings before tightening two mounting screws.
- Reconnect lead F1 to outboard brush and F2 to inboard brush.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Replace brush if wire inserts more than 1 inch (25 mm).
Full service-parts list: Cummins/Onan HDKC →, Cummins/Onan HDKCA →, Cummins/Onan HDKCB →
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.