A motor grader is a self-propelled earthmoving machine with a long, adjustable blade (the moldboard) mounted between the axles, used to level ground precisely and shape it to a required profile. It is mainly used in road and civil engineering and on large site-preparation projects.
How it works
The grader is a finishing machine: it moves small amounts of soil very accurately, rather than shifting large volumes like an excavator or bulldozer. Common uses include:
- Shaping the formation — levelling the sub-base for asphalt or paving and setting the fall
- Fine grading — pulling a site dead level before further work
- Creating falls — forming a slope for drainage, for example along verges and ditches
- Spreading base courses — distributing sub-base material such as crushed aggregate evenly
- Maintaining gravel roads — removing bumps and rutting
The blade adjusts in many directions: height, angle, side-shift and tilt. Modern graders often use GPS or laser machine control, so the profile is followed automatically to within a few millimetres. This improves accuracy and reduces the need for setting-out checks.
For smaller jobs there are towed grading blades behind a tractor, but the true motor grader is a machine for professional earthworks.
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