An earthmoving project has available one loader with a 6-cy heaped capacity bucket and a larger loader
Question:
An earthmoving project has available one loader with a 6-cy heaped capacity bucket and a larger loader with a 7-cy heaped capacity bucket for filling 45.9-cy heaped capacity off-road trucks. All equipment operates at 50-min hours. Loaders produce a bucket fill factor of 90%, and truck fill factor is 100%. Loaders do not “short load”. Loader cycle time is 0.6 min for both loaders (no travel). Truck dump time is 0.5 min (includes maneuvering, dumping, and turning). The loaded trucks climb uphill through the following three sections, and return empty downhill through the same sections. Trucks operate at rated loaded and empty weights.
Section | Load | Length (ft) | Speed loaded (mph) | Speed empty (mph) |
1 | full | 2,200 | 11 | 42 |
2 | full | 600 | 7 | 42 |
3 | empty | 1,100 | 8 | 42 |
Calculate the number of cycles per loader to fill each truck.
Calculate the number of trucks required for each loader.
Based on the number of trucks you determine develop a curve for the $/cy production cost vs. trucks curve for a range of ±2 trucks. Use the following hourly rates (including operator) for each piece of equipment (20 points)?
6-cy capacity loader $130/hr
7-cy capacity loader $140/hr
45.9-cy off-road truck $150/hr