I. When using a motor grader to dig roadside ditches or drainage ditches on a site, the following steps are typically followed:
1. Adjust the blade so that the plane angle is 35°, the cutting angle is 40°, and the tilt angle is approximately 9°.
2. Tilt the front wheels slightly toward the inside of the trench. Position the cutting edge of the blade approximately 15–30 cm from the outer edge of the trench. Drive the motor grader at low speed, slowly lower the blade, and begin cutting. During this initial cutting, the blade should not be lowered more than 10 cm, with the goal of marking the working line.
3. Once the working line is marked, proceed with deepening operations in stages according to the planned depth of the trench. For the first deepening pass, adjust the blade inclination angle to 11°, then gradually increase it to 16°, 21°, 26°, etc., increasing by 5° each time. Maintain the plane angle at 35–45° throughout. After each cutting pass, remove the excavated soil before proceeding to the next deepening operation. The
should be placed behind the rear wheels to avoid interfering with subsequent operations. The final cutting operation should achieve the full depth and width of the trench. 4. Once the trench has been excavated to its full depth, the outer slopes should be graded. If terrain conditions permit, the grader may straddle the trench, cutting the soil and placing it along the outer edge of the trench, or using the rear edge of the blade to cut the soil into the trench for subsequent removal. If terrain restrictions apply, the blade can be angled to one side of the machine. When the motor grader travels along the trench, it should maintain a distance of no less than 39 cm from the trench edge, first cutting the soil into the trench and then removing it.
II. Slope Grading
1. Before grading slopes, the blade should be adjusted to an angle toward the left or right.
2. When grading the slopes of side ditches, the scraping angle should be smaller; when grading the slopes of road embankments, road cuttings, dams, or trenches, the scraping angle should be larger; when grading vertical cliff slopes, the scraping angle may be adjusted to 90 degrees. However, note that the height of the cliff face should not exceed the length of the blade to prevent soil collapse and damage to the machine.
3. For slopes with a gradient of 3° to 4° and a width less than the length of the grader's blade, a single grader is sufficient to complete the grading task. The excavated soil can be removed during the return trip using the side-shift method.
4. For slopes wider than the length of the grader's blade, two graders must work in coordination. One grader scrapes soil downward from the embankment, while the other performs finishing work on the slope-facing edge of the subgrade. Initially, the upper grader should proceed approximately 10 meters ahead before the lower grader begins operations. This ensures that soil scraped by the upper grader does not interfere with the work of the lower grader. Simultaneously, the operator of the lower grader can align the two working surfaces to form a continuous slope, following the profile already established by the upper grader.230HP Motor Grader
