Cummins/Onan — Generator disassembly (revolving field)
Repair & overhaul · AC generator
From a Cummins/Onan service manual covering: 10.0JC, 12.5JC, 15.0JC, 4.0JB, 5.0JB, 6.0JB, 6.1JB, 7.5JB, 7.6JB. Check it applies to your exact model before use.
Applies to: Cummins/Onan 10.0JC, Cummins/Onan 12.5JC, Cummins/Onan 15.0JC, Cummins/Onan 5.0JB, Cummins/Onan 6.0JB, Cummins/Onan 6.1JB, Cummins/Onan 7.5JB, Cummins/Onan 7.6JB, Cummins/Onan JB engine, Cummins/Onan JC engine
Before you start
- Be careful not to let the stator touch or drag on the rotor
- Do not hit the collector rings, bearing or windings
Procedure
- Disconnect the battery to prevent accidental starting
- Remove the exciter cover and open the exciter to reveal the rotor-thru-stud nut
- Remove the four machine screws on the end bell near the bearing and lift out brush holders
- Remove lead from the tapped adjustable resistor in the generator air outlet
- Remove leads from control box to ignition system, choke and start disconnect switch
- Remove generator through-stud nuts, then remove end bell and stator assembly
- Remove baffle ring from adapter and loosen rotor from its tapered shaft fit
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan 10.0JC →, Cummins/Onan 12.5JC →, Cummins/Onan 15.0JC →, Cummins/Onan 5.0JB →, Cummins/Onan 6.0JB →, Cummins/Onan 6.1JB →, Cummins/Onan 7.5JB →, Cummins/Onan 7.6JB →
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.