2 pts Question 5 Question #3(b). A wheel tractor-scraper is operating on a level grade. Assume no power derating is required for equipment condition, altitude, and temperature and so on. Use the scraper specifications in Table 8.1 and the performance charts in Figure 8.8 and 8.9. What minimum value of coefficient of traction between the tractor wheels and the traveling surface is needed to satisfy the requirements of part 3(a) of this question? O 0.06 O 0.13 O 0.08 O 0.11 Gross weight 160 200 80 100 120 60 Cowes Png Equipment and Method 50 10 10 50 60 70 20 NO 30 20 15 15 1 20 10 - 15 35 40 45 50 0 5 20 25 30 10 15 3.3rd gear dir 4. 4th gear dir 5. Sth gear dir 6.6th gear di 7. 7th gear dir 8. Bth gear dir FIGURE 8. Reprinted cour 25 0 5 10 IS 20 Speed 1. gear toque converter drive 2. lad get torque converter drive Idea direct drive the direct drive 5. Sith per direct drive Napoved ones Cerpiller, Inc 6. 6th gear direct de 7. 7th gear direct de FIGURE 8.8 Papua performance chart for a Caterpillar 631 E scraper 8. Sth gear direct E Empty 43.945 L Loaded 77.965 km Chapter 8 Scrapers 233 Gross weight 100 75 130 175 Ib 6x1000) 40 50 60 307 70 80 kg (x1000) 2 225 16% Effective grade (grado minus rolling resistance) 109 5 19 50 40 45 55 km/h 35 10 30 15 20 25 30 35 mph 20 25 5 10 15 Speed E. Empty 43.945 kg (96.880 lb) L. Loaded 77.965 kg (171,880 lb) th 3. Ind gear direct drive 4.4th gear direct drive 5th gear direct drive gear direct drive 7.7 per direct drive gear direct drive FIGURE 8.9 Retarding performance chart for a Caterpillar 631E scraper Reped courtesy of Caterpillar, Inc