During setup, how much should the blade be lowered after positioning the grader center over the windrow?

The correct choice of lowering the blade by 4-6 inches after positioning the grader center over the windrow is appropriate as it ensures consistent and effective grading. Lowering the blade within this range allows for the optimal engagement with the material on the windrow without causing excessive disturbance to the underlying surface. This range strikes a balance—deep enough to cut into the windrow effectively, thereby allowing for proper material redistribution, yet not so deep that it creates unnecessary gouging or damage to the road surface underneath.

Moreover, this depth aids in achieving a uniform grade and efficient drainage, which are critical objectives during road maintenance and construction. Proper blade height also plays a significant role in the overall performance of the grader, influencing both the quality of the work produced and the operational ease, thereby enhancing productivity and reducing wear on the machine.

In contrast, the other depths mentioned are either too shallow or too deep for most grading applications, which could lead to inadequate engagement with the windrow or excessive disturbance and potential damage to the subgrade. Thus, the choice of 4-6 inches aligns with best practices used in road grading operations.