7 the estimated cycle time for a wheel single scraper is 6 5 min the l

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7. The estimated cycle time for a wheel single-scraper is 6.5 min. The load volume of the scraper is 24.3
BCY. A 45-min-per-hour efficiency factor will be used. Calculate the number of scrapers per pusher,
maximizing a production rate per hour. (Note: Consider the back-track method for a single pusher) (8)
pts)
8. Given the following information on a shovel/truck operation, determine the number of bucket loads
and the number of trucks at the highest production rate. (18 pts)
Shovel has a 3-cy bucket
Shovel cycle time is 20 sec
Bucket fill factor is 1.05
Job efficiency is 50-min per hour, and job condition is unfavorable
Maximum heaped volume of the rear-dump truck is 25 LCY (truck fill factor: 100 %)
Maximum payload is 56,000 lb
Material unit weight is 2,650 lb/LCY
Total truck travel time for haul and return is 8 min