Cummins/Onan OT-A-4060A / OT-C-10050C — Annual Preventive Maintenance
Maintenance · Transfer switch
For the Cummins/Onan OT-A-4060A / OT-C-10050C, from the Cummins/Onan service manual.
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Before you start
- The transfer switch presents a shock hazard that can cause severe personal injury or death unless all AC power is removed.
- Ignition of explosive battery gases can cause severe personal injury. Do not smoke or cause any spark, arc, or flame while servicing batteries.
Procedure
- Disconnect all sources of AC power; turn the generator set operation selector switch to Stop.
- Disconnect the external battery charger from its AC power source.
- Disconnect the set starting battery (negative lead first).
- Dust and vacuum all controls, meters, switching mechanism, interior buswork, and connecting lugs.
- Close the cabinet door and wash exterior surfaces with a damp sponge; do not allow water to enter the cabinet.
- Inspect buswork and supporting hardware for carbon tracking, cracks, corrosion, or deterioration.
- Check stationary and movable contacts; replace if necessary.
- Check control wiring and power cables for wear, deterioration, and loose connections.
- Check the cabinet interior for loose hardware and tighten.
- Tighten buswork, control wiring, power cables, and system hardware; retorque all cable lug connections.
- Service or replace the batteries.
- Reconnect the starting battery (negative lead last) and the normal AC power source.
- Verify proper operation of the battery charger.
- Test system operation and close and lock the cabinet door.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Lug torque values in Table 1-2
- Hardware torque values in section 4
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.