A hydraulic shovel will beused to excavate sandy clay and load it into 12-BCY dump trucks. The shovel’s production at 100%efficiency is estimated to be 300 BCY/h, and job efficiency is 0.80. Truck traveltime is estimated to be 8.0 min, and truck fixed-cycle time (excluding loading) is estimated to be 2.0 min. Equipment costs for the shovel and trucks are $40/h and $20/h, respectively. A.How many trucks are theoretically required to obtain maximum production?B. What is the expected production of the system in bank measure using this number of trucks?C. What is the expected unit loading and hauling cost($/BCY) ?

Explanation:

a)

Find the truck load time using relation

load time = Truck capacity/Shovel production

Substitute 12 BCY for truck capacity and 300 BCY/h for shovel production

load time = (12 BCY)/(300 BCY/h)=0.04h=0.04 x 60min=2.4min

Find the truck cycle time using relation

Truck cycle time = Load time + Travel + Fixed cycle time

Substitute 2.4 min for load time 8 min for travel time and 2 min for fixed cycle time

Truck cycle time = 2.4 + 8min + 2 min = 12.4 min

Find the number of trucks required using relation

Number of trucks = Truck cycle time/Load time

Substitute 12.4 min for truck cycle time and 2.4 min for load time

Number of trucks = 12.4/2.4=5.2=6

Therefore, the theoritical number of trucks required is 6

b)

Find the expected production using the relation

Production = shovel production (BCM/h) x Job efficiency

Substitute 300 BCY/h for shovel production and 0.80 for job efficiency

Production = 300 BCY/h x 0.80 = 240 BCY/h

Therefore, the expected production is 240 BCY/h

c)

Find the total cost of equipment per hour using relation

Total cost per hour = cost of shovel per hour + cost of 6 trucks per hour

Substitute $40 for cost of shovel per hour and $20 for cost of one truck per hour

Total cost = $40 + (6 x $20) = $160

calculate the unit cost of loading and hauling using relation

Unit cost loading and hauling = Equipment cost per hour/Equipment production per hour

Substitute $160 for the total equipment cost per hour 183.2 BCM/h for equipment production per hour

unit cost loading and hauling = $160/(240 BCY/h)=$0.667 BCY

Therefore, the uniy cost of loading and hauling is $0.667 BCY

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