Cummins/Onan — Servicing Brushes and Slip Rings
Repair & overhaul · Generator brush block
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HDKB
Before you start
- Disconnect the negative (-) cable at the battery before removing a panel or access door.
Procedure
- Disconnect the field leads from the brush block.
- Remove the mounting screw and withdraw the brush block from the end bell.
- Replace the brush block assembly if either brush is shorter than 7/16 inch (11 mm).
- Reconnect field leads: F- (black) to outside terminal, F+ (red) to inside terminal.
- Inspect slip rings; use a Scotch Brite pad or commutator stone for light wear.
Tools required
- Scotch Brite pad or commutator stone Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Replace brush if shorter than 7/16 inch (11 mm)
Full service-parts list: Cummins/Onan HDKB →
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.