A wheel-type tractor-scraper is operating on a level grade. Assume no power derating is...

A wheel-type tractor-scraper is operating on a level grade. Assume no power derating is required for equipment condition, altitude, temperature, etc. Use equipment data from Fig. 10.9.

a. Disregarding traction limitations, what is the maximum value of rolling resistance (in lb per ton) over which the fully loaded unit can maintain a speed of 20 mph?

b. What minimum value of coefficient of traction between the tractor wheels and the traveling surface is needed to satisfy the requirements of part (a)? For the fully loaded condition, 67% of the weight is distributed to the drive axle. Operating weight of the empty scraper is 70,000 lb.