(20 marks) A push-loaded scraper is used for hauling soil material and has a load capacity of 28.3 lcy; the rolling resistance of the scraper is 60 lb/ton. The haul distance is 2,800 A, with 2,000 ft @ +4% (uphill), with 800 ft @-1% (downhill) grade resistance. Acceleration/Deceleration at the start of the haul and return is 200 ft, with a speed of 5 mph. The maximum allowable speed for the scraper is 33mph. Assuming a 50 min-hour efficiency. The empty vehicle weight (EVW) of the scraper is 96,880 lbs: The moved material is dry clay (2,700 lbs/Icy) with a swell factor of 0.74 with 10% increase when push-loaded scraper is used. The scraper's cycle time information is given as below: Haul/Return time: calculated based on distance and total resistance Load time: 0.9min (pusher cycle time=1.5 min) Dump time: 0.4min Turn @ dump and @cut: 0.3min @ each (1) Calculate the cycle time of the scraper and decide how many scrapers are needed for this operation? Assuming one pusher is used. (2) What fleet structure is economical based on below machine cost information, if a total 500,000 bcy soil material is to be moved? Scraper O&O cost: $300/hr Pusher O&O cost: $360/hr Scraper operator: $50/hr Pusher operator: $54/hr Operator's fringe benefits 35% of the operator's wage GROSS WEIGHT lb x 1000 150 kg x 1000 30 40 50 60 80 100 120 160 200 lb x 1000 1 UULILULIITTITUU 15 20 30 40 50 60 70 90 kg x 1000 65 120 100 55 45 35 70 25 50 30% 25% 20% 20 40 15 30 15% 1296 10 20 10% RIMPULL 8 TOTAL RESISTANCE (Grade plus Rolling Resistance) 8% 15 6 10 5% 4 4% 396 5 2 2 0 5 10 15 20 25 30 35 40 45 50 55 kmvh 5 10 15 20 25 30 35 mph SPEED Massage