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P&H 4100 Swing Gearcase Sun Pinion Shaft Bearing Case Study
Background
The front and rear gearcases are monitored on a 13-week cycle. The gearcase is a direct drive, reversing, variable speed, planetary gear unit. The shovel operates approximately 6,000 hours per year with a minimum down time cost of $4200 per hour. |
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Detection
A survey of the rear swing gearcase showed evidence of a planetary sun pinion localized defect as illustrated in the vibration spectrum shown on the right. The vibration component increases with respect to the reference spectrum are highlighted in red and the planetary sun pinion localized defect harmonic series is superimposed on the figure. The figure shown at lower right details the planetary sun pinion localized defect harmonic trend over time. |
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Strip Down Inspection
The swing gearcase was replaced at approximately 40,000 hours with a service exchange unit. The gearcase change-out was conducted during a scheduled outage. Inspection of the planetary gear system confirmed the rear swing gearcase planetary sun pinion localized defect. The figure on the right illustrates the extent of the rear swing gearcase sun gear localized defect. |
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| Cost Benefit Analysis |
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Production Downtime Saving |
Repair Cost Saving |
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The planned change out without any secondary damage is typically 12 hours and an unplanned change out is 24 to 48 hours depending on the secondary damage. Thus savings in the range $50,400 to $151,200. |
In service failure would have resulted in a combination of sun pinion, planet gears & bearings, planetary carrier, gearcase and 1st stage gear set damage. In the worst case, the gearcase could have been a written off. |
| Mid Range Savings |
$USD 100,800 |
$USD 80,000 |
| ROI |
1947% |
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