Locomotive Napier SA085 Turbocharger Overhaul

Background

The locomotive operator asked us to overhaul their Napier SA085 turbocharger, which includes full dismantle, inspection, clean, rebuild and testing.

Outcome

Due to the fretting that had been found on the compressor wheel adjusting shim, the item was stoned flat before the shaft assemblies were balanced.

All of the threads that were found to be below the manufacturer’s specification were re-tapped or replaced as per the standard overhaul procedure. All internal special gaskets were replaced as they were not reusable.

The turbine blades were all removed in order to rectify the pitting damage found on inspection.

The blades were also removed so that the damper wire could be renewed. The blades were all redressed and the scored journals were polished.

In order to rectify the cracks that were identified in the housing, the unit was welded prior to refitting.

All internal parts subject to corrosion were painted using red oxide.

The turbocharger was then reassembled using all new replacement parts. The unit was then painted and placed in despatch in preparation for packing and sending to the client, after which the unit was externally finish painted and move to despatch.

Quality Assurance

Once the rotor assembly had been repaired and the turbine blades were refitted, this was then checked for free rotation and balanced. No issues were recorded during this process.

During the rebuild process, the turbocharger casing was then pressure tested at 50 PSI for 30 minutes

Items Repaired/Replaced

1. Bearings – Replaced
2. Joints & Seals – Replaced
3. Bearing Turbine End – Replaced
4. Tab washers – Replaced
5. Nuts – Replaced
6. Shroud Washer – Replaced
7. Rotor Assembly – Repaired
8. O ring – Replaced
9. Exhaust Inlet Housing – Repaired
10. Nozzle Ring Assembly – Repaired