| Scraper Production Estimating |
| Using the Scraper Production Estimating Format outlined in your textbook and the scraper specifications in Table 8.1 and on the performance charts in Figures 8.10 and 8.11, analyze the probable scraper production. The material to be hauled is a dry earth weighing 2,800 lb/bcy. The expected rolling resistance for the haul route is 80 lb/ton. Use a load time of 0.80 minutes, which will result in an average haul load of 90% heaped capacity. To account for both acceleration and decelaration, use an average speed of 6 mph over a distance of 200 ft. Use a 55-min hour efficiency factor. The total length of haul is 2,000 ft and has the following individual segments when moving from cut to fill: |
| 600 lf @ 4% grade |
| 1000 lf @ 0% grade |
| 400 lf @ 6% grade |
| Total Ownership and Operating Costs (including operator) |
| 631E Scraper | | $115/hr |
| D9 Dozer | | $165/hr |
| Using the most economical number of scrapers, how much will it cost per BCY to haul under the stated conditions? |
| Step 1. Weight |
| Step 2. Rolling Resistance |
| Step 3-6. Grade Resistance, Total Resistance, Travel Speed, Travel Time |
| | | Distance | | Step 2 | Step 3 | Step 4 | Step 5 | Step 6 |
| | | (ft) | | RR % | GR % | TR % | Speed (mph) | Time (min) |
| | Haul (? Lbs) | | acc |
| | | | dec |
| | Return (? Lbs) | | acc |
| | | | dec |
| | | | | | | | Travel Time: |
| Step 7. Load Time |
| Step 8. Dump Time |
| Step 9. Turning Times |
| Step 10. Total Cycle Time |
| Step 11. Pusher Cycle Time |
| Step 12. Balance Fleet |
| Step 13. Efficiency |
| Step 14. Production |
| Step 15. Cost |
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hw8cne243.xlsx
