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Cummins/Onan — Generator Brush Block Service

A Cummins/Onan service procedure — check it applies to your exact model before use.

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Before you start

  • Accidental or remote starting can cause severe personal injury or death. Before removing a panel or access door, disconnect the negative (-) cable at the battery to prevent the engine from starting.

Procedure

  1. Remove the access panel on the left end of the enclosure for access to the brush block.
  2. Disconnect the field leads from the brush block.
  3. Remove the mounting screw and withdraw the brush block from the generator end bell.
  4. Replace the brush block assembly if either brush is shorter than 7/16 inch (11 mm), binds in the brush block or is damaged in any way.
  5. Reconnect the field leads, F- (black) to the outside terminal, and F+ (red) to the inside terminal.

Specs & torque values

  • Brush minimum length: 7/16 inch (11 mm)

Source: manual:981-0535 Onan HDKBA HDKBB Mobile Genset Service manual (10-2002).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.