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Cummins/Onan — Generator Assembly - Rotor Components Pre-assembly

For these Cummins/Onan models: 4.4X, 7.7X, 8.9X, M-1641.

Applies to: Cummins Onan 8 9X, Cummins Onan M 1641

Procedure

  1. Mount the disk and fan assembly, tighten capscrews to 200 to 240 ft-lb (271 to 325 N•m).
  2. Mount exciter rotor onto keyed shaft so that rectifiers face out.
  3. Locate toothed locking washer flush against exciter rotor with keyway tab properly positioned.
  4. Mount the locking ring against the toothed locking washer and tighten to 450 to 500 ft-lb (610 to 678 N•m).
  5. Bend over a locking washer tooth (tab) into groove of locking ring.
  6. Install bearing onto rotor shaft using proper bearing installation tool, applying pressure to inner race only.
  7. Locate toothed locking washer flush against bearing with keyway tab properly positioned.
  8. Mount the locking ring against the toothed locking washer and tighten to 150 to 200 ft-lb (203 to 271 N•m).
  9. Bend over a locking washer tooth (tab) into groove of locking ring.

Tools required

  • bearing installation tool

Specs & torque values

  • Disk and fan assembly torque: 200-240 ft-lb (271-325 N•m)
  • Exciter rotor locking ring torque: 450-500 ft-lb (610-678 N•m)
  • Bearing locking ring torque: 150-200 ft-lb (203-271 N•m)

Source: manual:943-0018 Onan UV Generator w-Torque Match-2 Regulator Service manual (10-1986).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.