Cummins/Onan — Engine Speed / Governor Adjustment
Adjustments · Roosa-Master governor / injection pump
From a Cummins/Onan operator's manual covering: 40.0DDB-515R, 50.0DDB-15R, 50.0DDB-9XR. Check it applies to your exact model before use.
Applies to: Cummins/Onan 40.0DDB-515R, Cummins/Onan 50.0DDB-15R, Cummins/Onan 50.0DDB-9XR, John Deere 6329D engine, John Deere 6329D (300-6329D) engine
Procedure
- Back off the high speed stop screw.
- Screw in the low speed adjusting screw until the frequency meter reads 60 Hz (generator on load).
- Turn in the high speed adjusting screw until it bottoms; secure the locknuts.
- Adjust governor sensitivity (droop) with the external knurled knob at rear of injector pump housing.
Specs & values
- Adjust engine speed to 1800 rpm for 60 Hz sets and 1500 rpm for 50 Hz sets
- Speed droop set for 3 percent to 5 percent regulation from no-load to full-load
Full service-parts list: Cummins/Onan 40.0DDB-515R →, Cummins/Onan 50.0DDB-15R →, Cummins/Onan 50.0DDB-9XR →, John Deere 6329D engine →, John Deere 6329D (300-6329D) engine →
Source: Cummins/Onan operator's 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.