A wheel tractor-scraper is operating on a level grade. Assume no power derating is required for equipment condition, altitude, and temperature. Use equipment data from Figure 6.10.  a. Disregarding traction limitations, what is the maximum value of rolling resistance (in lb/ton) over which the fully loaded unit can maintain a speed of 15 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, 52% of the weight is distributed to the drive axle. Operating weight of the empty scraper is 74,946 lb.

6.11 A wheel tractor-scraper is operating on a level grade. Assume no power derating is
required for equipment condition, altitude, and temperature. Use equipment data from
Figure 6.10. 
a. Disregarding traction limitations, what is the maximum value of rolling resistance (in
lb/ton) over which the fully loaded unit can maintain a speed of 15 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, 52% of the weight is distributed to the drive axle. Operating weight of the
empty scraper is 74,946 lb.