Reference no: EM132158443
1. A truck for which the information in. Figure applies operates over a haul road with a +4% slope and a rolling resistance of 90 lb/ton. If the gross vehicle weight is 70,000 lb. determine the truck's maximum speed.
2. A project to move packed earth requires you to decide whether to use a dozerlscraper operation or excavator/truck operation. Determine the most economical operation based on the dcpzeriscraper operation estimated at $1.25/cy. All equipment carries a rated heaped capacity, has a fill factor of 100%, and works 45-min hours. Excavator costs $95/hr (including operator), cycle time is 0.28 min, and bucket heaped capacity is 5.0 cy. Truck costs $150/hr (including operator), dump time is 0.5 min (maneuver, dump, turn), heaped capacity is 31.7 cy, and 12 trucks are available for the project. Hauling equipment operates in one direction from A to B to C and finally to D.
|
Section
|
Load
|
Length (ft)
|
Speed (mph)
|
|
A
|
full
|
3,000
|
9
|
|
13
|
full
|
2,500
|
17
|
|
C
|
empty
|
3,000
|
36
|
|
D
|
empty
|
3,000
|
16
|
3. 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
|
2,000
|
10
|
42
|
|
2
|
full
|
500
|
7
|
42
|
|
3
|
empty
|
1,000
|
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 -1-2 trucks. Use the following hourly rates (including operator) for each piece of equipment:
6-cy capacity loader $120/hr 7-cy capacity loader $125/hr 45.9-cy off-mad truck $130/hr