Cummins/Onan — Adjusting Governor (Mechanical)
Adjustments
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HGJAA, Cummins/Onan HGJAB, Cummins/Onan HGJAC, Cummins/Onan HGJAD, Cummins/Onan HGJAE, Cummins/Onan HGJAF
Before you start
- Disconnect voltage/frequency-sensitive devices before governor adjustments
Procedure
- Warm up genset 5 minutes at 1/2 to 3/4 rated load.
- Adjust frequency near Table value with speed adjusting nut.
- With no load, set idle stop screw to 51-53 Hz (60 Hz set) or 41-43 Hz (50 Hz set).
- Recheck and re-adjust no-load frequency.
- Bump governor arm to confirm frequency stabilizes.
- Connect rated load and check droop.
- Move governor spring hook to correct droop.
- Recheck frequency and droop; ensure no hunting.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Droop 2-4 Hz
- No-load 63/62 Hz (60 Hz sets)
- Governor speed within 5% of rated
Full service-parts list: Cummins/Onan HGJAA →, Cummins/Onan HGJAB →, Cummins/Onan HGJAC →, Cummins/Onan HGJAD →
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.