Cummins/Onan — Adjusting Mechanical Governor
Adjustments
From a Cummins/Onan service manual covering: 5.5 HGJAA, 5.5 HGJAB, 5.5 HGJAC, 5.5 HGJAD, 5.5 HGJAE, 5.5 HGJAF, 7.0 HGJAA, 7.0 HGJAB, 7.0 HGJAC, 7.0 HGJAD, 7.0 HGJAE, 7.0 HGJAF. Check it applies to your exact model before use.
Applies to: Cummins/Onan 5.5 HGJAD, Cummins/Onan 5.5 HGJAE, Cummins/Onan 7.0 HGJAD, Cummins/Onan 7.0 HGJAE
Before you start
- Voltage/frequency-sensitive equipment may be damaged; disconnect before adjusting
Procedure
- Warm up genset five minutes at 1/2 to 3/4 rated load.
- Adjust frequency to Table 8-4 value with speed adjusting nut.
- With engine warm and no loads, set idle stop screw to 51-53 Hz (60 Hz).
- Recheck no-load frequency and bump governor arm for stability.
- Connect rated load; move governor spring hook to correct droop.
- Check for hunting under the specified load sequence.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- No-load droop 2-4 Hz
- Idle 51-53 Hz (60 Hz genset), 41-43 Hz (50 Hz genset)
Full service-parts list: Cummins/Onan 5.5 HGJAD →, Cummins/Onan 5.5 HGJAE →, Cummins/Onan 7.0 HGJAD →, Cummins/Onan 7.0 HGJAE →
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.