Gearbox Inspection Report

1. Gearbox History.

   The history of this gearbox shows that it has provided good service. (12 years) The two previous occasions that the gearbox was in the workshop was for a bearing and seal replacement. The gears are still of original supply.

2. Gearbox Inspection.

2.1  Observations.

1. There was excessive back-lash on the bevel pinion shaft.
2. The oil in the gearbox has deteriorated.
3. The first intermediate pinion has quite serious pitting on the working flank. The bearings also show signs of sever wear.
4. The low speed gear has minor pitting on intermittent teeth.
5. The second intermediate shaft's taper roller bearings are worn. When the shaft is turned the bearing elements skid on occasion.

2.2  Analysis.

1. Shafts.
   All the shafts appear to be re-usable. A 'Magnetic Particle Inspection' will be applied to confirm this.
2. Oil analysis.
   The oil smelt burnt and was black. No tests were done but the oil had exceeded its useful life.
3. Gears.

• Poor contact pattern on the bevel-set. Contact was towards the toe of the gears, and wear was the result. This can be attributed to the worn taper roller bearings.
• The contact between the low-speed gear and first intermediate pinion was also concentrated on the leading edge of the gears. This was caused by the wear of the bearings, allowing the ends of the shaft to sag, thus changing the contact of the gears.

4. Housing.
   The housing shows no signs of cracks and the bores are in good condition.
5. Bearings.

• The bearings on the low-speed shaft appear to be in good condition and could be reused.

3. Conclusion and Repairs.
   The bevel set is in a condition to be reused. The poor oil quality has led to accelerated bearing wear. The oil should be replaced at least every 8000hours. All the bearings, except those on the low speed shaft will be replaced, as well as all seals and ground rings.