2. A wheel-tractor scraper is operating on a level grade. Assume no power derating is required for equipment condition,

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2 A Wheel Tractor Scraper Is Operating On A Level Grade Assume No Power Derating Is Required For Equipment Condition 1 (27.88 KiB) Viewed 54 times

tables 8.1 8.8 and 8.9 below

2 A Wheel Tractor Scraper Is Operating On A Level Grade Assume No Power Derating Is Required For Equipment Condition 2 (29.85 KiB) Viewed 54 times

2 A Wheel Tractor Scraper Is Operating On A Level Grade Assume No Power Derating Is Required For Equipment Condition 3 (56.05 KiB) Viewed 54 times

2 A Wheel Tractor Scraper Is Operating On A Level Grade Assume No Power Derating Is Required For Equipment Condition 4 (44.45 KiB) Viewed 54 times

2. A wheel-tractor scraper is operating on a level grade. Assume no power derating is required for equipment condition, altitude, temperature, and so on. Use the scraper specifications in table 8.1 and the performance chart in figures 8.8 and 8.9. a. Disregarding traction limitations, what is the max. value of rolling resistance (in pounds per ton) over which the empty scraper can maintain a speed of 23 mph? b. What min. value of coefficient of traction between the tractor wheels and the traveling surface is needed to satisfy the requirements of part a of this question. (25 points)
21 cy TABLE 8.1 Specifications for a Caterpillar 631E scraper Engine: flywheel power 450 Transmission: semiautomatic power shift, eight speeds Capacity of scraper: Struck Heaped 31 cy Weight distribution: Empty Drive axle 67% Rear axle 33% Loaded Drive axle 53% Rear axle 47% Operating weight: Empty 96,880 lb* Rated load: 75,000 lb Top speed: Loaded 33 mph "Includes coolant, lubricants, full fuel tank, rollover protective system (ROPS) canopy, and operator
Gross weight 30 50 60 80 100 120 160 200 lb (x1000) 15 20 30 40 50 60 70 90 kg (x1000) 40 لللللللللللاهلها Ib kg (x1000) (x1000) 150 65 120 55 100 45 DI 35 TUILL +---+ TTT 70 日 25 50 30% 259 209 20 40 IS 30 HAN 155 10 126 20 105 Rimpull 8 Total resistance (grade plus rolling resistance) 89 15 6 10 69 59 4 45 356 39 25 0 5 10 15 20 25 30 35 40 45 50 55 km/h 10 1. Ist gear torque converter drive 2. 2nd gear torque converter drive 3. 3rd gear direct drive 4.4th gear direct drive 5. 5th gear direct drive 15 20 25 30 35 mph Speed 6. 6th gear direct drive 7. 7th gear direct drive & 8th gear direct drive E Empty 43.945 kg (96.880 lb) L Loaded 77.965 kg (171.880 lb) 360
55 75 Gross weight 150 100 175 1b (x1000) 60 302 70 80 kg (x1000) 225 169 Effective grade (grade minus rolling resistance) 10% 56 1 IS T 10 1 T 1 45 1 35 0 T 30 3 15 25 20 30 SO 55 km/h 0 10 20 25 30 35 mph 15 Speed E. Empty 43.945 kg (96880 lb) L. Loaded 77.965 kg (171,880 tb) 3. 3rd gear direct drive 4.4th gear direct drive 5.5th gear direct drive 6.6th gear direct drive 7.7th gear direct drive 8.8th gear direct drive 362